recovering purified material from the crude mixture

Abstract

The present disclosure relates to a process and apparatus for recovering purified material from a crude mixture, such as a process and apparatus for recovering purified 2-methyl glutaronitrile from a crude mixture obtained from an industrial nitrile manufacturing process.

Description

Cross-references to related applications

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 63 / 555,916, filed February 21, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure relates to a method for recovering purified materials from crude mixtures, such as 2-methylglutaronitrile, from crude mixtures obtained from industrial nitrile manufacturing processes. Background Technology

[0003] 2-Methylglutaronitrile, a six-carbon aliphatic branched dinitrile, is a useful chemical intermediate, also known as MGN. MGN can be obtained as a byproduct in the manufacture of industrial dinitrile (specifically, adiponitrile). Streams containing the byproduct MGN may contain measurable amounts of 2-ethylbutadionitrile (ESN), adiponitrile (ADN), glycols, phenols, cresols, catechols, other substituted nitriles, trivalent or pentavalent phosphorus substances, etc.

[0004] It may be desirable to collect a large volume of crude MGN stream and further purify it to a high-purity form (e.g., purity ≥ 99.1% by weight). DYTEK ® MGN (2-methylglutaronitrile) is an example of a commercial MGN product with a purity ≥99.1% by weight. DYTEK ® MGN is a high-boiling-point specialty intermediate used in the fiber, solvent, and polymer industries.

[0005] Impurities present in purified MGN can affect the catalytic hydrogenation process used to convert MGN into its corresponding branched aliphatic diamine, 2-methylpentamethylenediamine (MPMD). The most significant impurity in this regard is the ESN impurity, which has a boiling point close to that of MGN. Another process impurity is 2-cyanocyclopentadiene imine (CPI).

[0006] There is still an industrial need for a commercially viable method to recover and purify 2-methylglutaronitrile from industrial nitrile manufacturing processes, with reduced levels of impurities that are detrimental to the catalytic hydrogenation of MGN.

[0007] Hexamethyleneimine (HMI) is another byproduct formed in the process of producing adiponitrile from butadiene via hydrocyanation. There remains an industrial need for a commercially viable method to recover and purify HMI from industrial nitrile manufacturing processes with reduced impurity levels.

[0008] 1,2-Diaminocyclohexane (DCH) is a byproduct formed in the process of hydrogenating diamines to produce diamines. There remains an industrial need for a commercially viable method to recover and purify DCH from industrial nitrile hydrogenation processes, with reduced impurity levels. Summary of the Invention

[0009] Various aspects of this disclosure provide a method for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70% to about 90% by weight of 2-methylglutaronitrile, about 1% to about 20% by weight of 2-ethylbutadionitrile, about 1% to 15% by weight of adiponitrile, about 0.05% to about 5% by weight of 2-cyanocyclopentylimine, and about 0.01% to about 2% by weight of other impurities. The method includes distilling the crude mixture in a first distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first overhead stream, the first bottom stream comprising ≤1% by weight of 2-ethylbutadionitrile by mass of the total first bottom stream, and the first overhead stream comprising ≤1% by weight of adiponitrile by mass of the total first overhead stream. The method includes distilling the first bottom stream in a second distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream containing ≥80% of 2-cyanocyclopentadiene imine present in the crude mixture. The method includes obtaining at least one of a second overhead stream and a side-draw stream from the second distillation unit. Optionally, the method includes distilling at least one of the second overhead stream and the side-draw stream in a third distillation unit having a head pressure in the range of 10 mmHg to 80 mmHg to produce a third overhead stream and a third bottom stream, the third overhead stream containing ≤0.1 wt% of 2-cyanocyclopentadiene imine by mass of the total third overhead stream, and the third bottom stream containing ≤0.5 wt% of 2-ethylbutadionitrile by mass of the total third bottom stream. The method further includes combining the first overhead stream, the second bottom stream, and optionally the third bottom stream to form a tailings mixture containing 1% to 30% by weight of 2-cyanocyclopentadiene imine by weight of the total tailings mixture. Optional distillation is not performed on at least one of the second overhead stream and the side-draw stream in the third distillation unit, wherein the second overhead stream, the side-draw stream, or a combination thereof is purified 2-methylglutaronitrile; or optional distillation is performed on at least one of the second overhead stream and the side-draw stream in the third distillation unit, wherein the third overhead stream is purified 2-methylglutaronitrile. The purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentylimine and ≤0.2% by weight of water.

[0010] Various aspects of this disclosure provide a method for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70% to about 90% by weight of 2-methylglutaronitrile, about 1% to about 20% by weight of 2-ethylbutadionitrile, about 1% to 15% by weight of adiponitrile, about 0.05% to about 5% by weight of 2-cyanocyclopentylimine, and about 0.01% to about 2% by weight of other impurities. The method includes distilling the crude mixture in a first distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first overhead stream, the first bottom stream comprising ≤1% by weight of 2-ethylbutadionitrile by mass of the total first bottom stream, and the first overhead stream comprising ≤1% by weight of adiponitrile by mass of the total first overhead stream. The method includes distilling the first bottom stream in a second distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream containing ≥80% of 2-cyanocyclopentadiene imine present in the crude mixture. The method includes obtaining at least one of a second overhead stream and a side feed stream from the second distillation unit. The method further includes combining the first overhead stream and the second bottom stream to form a tailings mixture containing 1% to 30% by weight of 2-cyanocyclopentadiene imine by weight of the total tailings mixture. The second overhead stream, the side feed stream, or a combination thereof is purified 2-methylglutaronitrile. The purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentylimine and ≤0.2% by weight of water.

[0011] Various aspects of this disclosure provide a method for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70% to about 90% by weight of 2-methylglutaronitrile, about 1% to about 20% by weight of 2-ethylbutadionitrile, about 1% to 15% by weight of adiponitrile, about 0.05% to about 5% by weight of 2-cyanocyclopentylimine, and about 0.01% to about 2% by weight of other impurities. The method includes distilling the crude mixture in a first distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first overhead stream, the first bottom stream comprising ≤1% by weight of 2-ethylbutadionitrile by mass of the total first bottom stream, and the first overhead stream comprising ≤1% by weight of adiponitrile by mass of the total first overhead stream. The method includes distilling the first bottom stream in a second distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream containing ≥80% of 2-cyanocyclopentadiene imine present in the crude mixture. The method includes obtaining at least one of a second overhead stream and a side-draw stream from the second distillation unit. The method further includes distilling at least one of the second overhead stream and the side-draw stream in a third distillation unit having a head pressure in the range of 10 mmHg to 80 mmHg to produce a third overhead stream and a third bottom stream, the third overhead stream containing ≤0.1 wt% of 2-cyanocyclopentadiene imine by mass of the total third overhead stream, and the third bottom stream containing ≤0.5 wt% of 2-ethylbutadionitrile by mass of the total third bottom stream. The method further includes combining the first overhead stream, the second bottom stream, and the third bottom stream to form a tailings mixture containing 1% to 30% by weight of 2-cyanocyclopentadiene imine by mass of the total tailings mixture. The third overhead stream is purified 2-methylglutaronitrile. The purified 2-methylglutaronitrile contains ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentadiene imine, and ≤0.2% by weight of water by mass of the purified 2-methylglutaronitrile.

[0012] Various aspects of this disclosure provide a method for recovering purified hexamethyleneimine (HMI) from a crude mixture comprising about 80% to about 90% by weight of HMI, about 5% to about 15% by weight of n-hexylamine, about 0% to 5% by weight of water, about 0% to 5% by weight of cyclohexylamine, and about 0% to about 5% by weight of hexamethylenediamine (HMD). The method includes distilling the crude mixture in a first distillation unit having a head pressure in the range of 400 mmHg to 500 mmHg to produce a first bottom stream and a first overhead stream, the first bottom stream containing concentrated HMI containing HMD, and the first overhead stream containing n-hexylamine and optionally water. The method further includes distilling the first bottom stream in a second distillation unit having a head pressure in the range of 100 mmHg to 200 mmHg to produce a second bottom stream containing concentrated HMD containing HMI. The method further includes obtaining at least one of a second overhead stream and a side feed stream from the second distillation unit. The second overhead stream, the side feed stream, or a combination thereof is purified HMI. The purified HMI is at least 99% by weight HMI.

[0013] Various aspects of this disclosure provide a method for recovering purified 1,2-diaminocyclohexane (DCH) from a crude mixture comprising about 65 wt% to about 80 wt% DCH, about 10 wt% to about 20 wt% hexamethylenediamine (HMD), about 0 wt% to 5 wt% hexamethyleneimine (HMI), about 0 wt% to about 5 wt% 2-(aminomethyl)-cyclopentanamine (AMC), about 0 wt% to about 5 wt% 2-methyl-pentamethylenediamine (MPMD), and about 0 wt% to about 2 wt% other impurities comprising n-hexylamine, cyclohexylamine, or combinations thereof. The method includes distilling the crude mixture in a first distillation unit having a head pressure in the range of 700 mmHg to 850 mmHg to produce a first bottom stream and a first overhead stream, the first bottom stream comprising concentrated DCH optionally containing HMD, AMC, MPMD, or combinations thereof, and the first overhead stream comprising HMD and optionally containing AMC, MPMD, or combinations thereof. The method includes distilling the first bottom stream in a second distillation unit having a head pressure in the range of 100 mmHg to 200 mmHg to produce a second bottom stream, the second bottom stream containing concentrated HMD containing DCH and optionally AMC, MPMD, or a combination thereof. The method also includes obtaining at least one of a second overhead stream and a side feed stream from the second distillation unit. The second overhead stream, the side feed stream, or a combination thereof is purified DCH. The purified DCH is at least 98.5% by weight DCH.

[0014] Various aspects of this disclosure provide an apparatus for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70% to about 90% by weight of 2-methylglutaronitrile, about 1% to about 20% by weight of 2-ethylbutadionitrile, about 1% to 15% by weight of adiponitrile, about 0.05% to about 5% by weight of 2-cyanocyclopentylimine, and about 0.01% to about 2% by weight of other impurities. The apparatus includes a first distillation unit configured to distill the crude mixture at a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first overhead stream, the first bottom stream comprising ≤1% by weight of 2-ethylbutadionitrile by mass of the total first bottom stream, and the first overhead stream comprising ≤1% by weight of adiponitrile by mass of the total first overhead stream. The apparatus includes a second distillation unit configured to distill the first bottom stream at a head pressure ranging from 20 mmHg to 100 mmHg to produce a second bottom stream containing ≥80% of 2-cyanocyclopentadiene imine present in the crude mixture. The second distillation unit is configured to provide at least one of a second overhead stream and a side-draw stream. Optionally, the apparatus includes a third distillation unit configured to distill at least one of the second overhead stream and the side-draw stream at a head pressure ranging from 10 mmHg to 80 mmHg to produce a third overhead stream and a third bottom stream. The third overhead stream contains ≤0.1 wt% 2-cyanocyclopentadiene imine by mass of the total third overhead stream, and the third bottom stream contains ≤0.5 wt% 2-ethylbutadionitrile by mass of the total third bottom stream. The apparatus includes one or more flow channels configured to combine the first overhead stream, the second bottom stream, and optionally the third bottom stream to form a tailings mixture containing 1% to 30% by weight of 2-cyanocyclopentadiene imine by mass of the total tailings mixture. The optional third distillation unit is absent, and the second overhead stream, the side feed stream, or a combination thereof is purified 2-methylglutaronitrile; or the optional third distillation unit is present, and the third overhead stream is purified 2-methylglutaronitrile. The purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentadiene imine, and ≤0.2% by weight of water.

[0015] Various aspects of this disclosure provide an apparatus for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70% to about 90% by weight of 2-methylglutaronitrile, about 1% to about 20% by weight of 2-ethylbutadionitrile, about 1% to 15% by weight of adiponitrile, about 0.05% to about 5% by weight of 2-cyanocyclopentylimine, and about 0.01% to about 2% by weight of other impurities. The apparatus includes a first distillation unit configured to distill the crude mixture at a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first overhead stream, the first bottom stream comprising ≤1% by weight of 2-ethylbutadionitrile by mass of the total first bottom stream, and the first overhead stream comprising ≤1% by weight of adiponitrile by mass of the total first overhead stream. The apparatus includes a second distillation unit configured to distill the first bottom stream at a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream containing ≥80% of the 2-cyanocyclopentadiene imine present in the crude mixture. The second distillation unit is configured to provide at least one of a second overhead stream and a side feed stream. The apparatus also includes one or more flow channels configured to combine the first overhead stream and the second bottom stream to form a tailings mixture containing 1% to 30% by weight of 2-cyanocyclopentadiene imine by weight of the total tailings mixture. The second overhead stream, the side feed stream, or a combination thereof is purified 2-methylglutaronitrile. The purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentylimine and ≤0.2% by weight of water.

[0016] Various aspects of this disclosure provide an apparatus for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70% to about 90% by weight of 2-methylglutaronitrile, about 1% to about 20% by weight of 2-ethylbutadionitrile, about 1% to 15% by weight of adiponitrile, about 0.05% to about 5% by weight of 2-cyanocyclopentylimine, and about 0.01% to about 2% by weight of other impurities. The apparatus includes a first distillation unit configured to distill the crude mixture at a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first overhead stream, the first bottom stream comprising ≤1% by weight of 2-ethylbutadionitrile by mass of the total first bottom stream, and the first overhead stream comprising ≤1% by weight of adiponitrile by mass of the total first overhead stream. The apparatus includes a second distillation unit configured to distill the first bottom stream at a head pressure ranging from 20 mmHg to 100 mmHg to produce a second bottom stream containing ≥80% of 2-cyanocyclopentadiene imine present in the crude mixture. The second distillation unit is configured to provide at least one of a second overhead stream and a side-draw stream. The apparatus also includes a third distillation unit configured to distill at least one of the second overhead stream and the side-draw stream at a head pressure ranging from 10 mmHg to 80 mmHg to produce a third overhead stream and a third bottom stream. The third overhead stream contains ≤0.1% by weight of 2-cyanocyclopentadiene imine by mass of the total third overhead stream, and the third bottom stream contains ≤0.5% by weight of 2-ethylbutadionitrile by mass of the total third bottom stream. The apparatus also includes one or more flow channels configured to combine the first overhead stream, the second bottom stream, and the third bottom stream to form a tailings mixture containing 1% to 30% by weight of 2-cyanocyclopentadiene imine by mass of the total tailings mixture. The third overhead stream is purified 2-methylglutaronitrile. The purified 2-methylglutaronitrile contains ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentadiene imine, and ≤0.2% by weight of water by mass of the purified 2-methylglutaronitrile.

[0017] Various aspects of this disclosure provide an apparatus for recovering purified hexamethyleneimine (HMI) from a crude mixture comprising about 80% to about 90% by weight of HMI, about 5% to about 15% by weight of n-hexylamine, about 0% to 5% by weight of water, about 0% to 5% by weight of cyclohexylamine, and about 0% to about 5% by weight of hexamethylenediamine (HMD). The apparatus includes a first distillation unit configured to distill the crude mixture at a head pressure in the range of 400 mmHg to 500 mmHg to produce a first bottom stream and a first overhead stream, the first bottom stream containing concentrated HMI containing HMD, and the first overhead stream containing n-hexylamine and optionally containing water. The apparatus further includes a second distillation unit configured to distill the first bottoms stream at a head pressure in the range of 100 mmHg to 200 mmHg to produce a second bottoms stream containing concentrated HMD containing HMI. The second distillation unit is configured to provide at least one of a second overhead stream and a side feed stream. The second overhead stream, the side feed stream, or a combination thereof is purified HMI. The purified HMI is at least 99% by weight.

[0018] Various aspects of this disclosure provide an apparatus for recovering purified 1,2-diaminocyclohexane (DCH) from a crude mixture comprising about 65% to about 80% by weight of DCH, about 10% to about 20% by weight of hexamethylenediamine (HMD), about 0% to 5% by weight of hexamethyleneimine (HMI), about 0% to about 5% by weight of 2-(aminomethyl)-cyclopentanamine (AMC), about 0% to about 5% by weight of 2-methyl-pentamethylenediamine (MPMD), and about 0% to about 2% by weight of other impurities comprising n-hexylamine, cyclohexylamine, or combinations thereof. The apparatus includes a first distillation unit configured to distill the crude mixture at a head pressure in the range of 700 mmHg to 850 mmHg to produce a first bottom stream and a first overhead stream. The first bottom stream contains concentrated DCH, optionally containing HMD, AMC, MPMD, or a combination thereof. The first overhead stream contains HMD and optionally contains AMC, MPMD, or a combination thereof. The apparatus also includes a second distillation unit configured to distill the first bottom stream at a head pressure in the range of 100 mmHg to 200 mmHg to produce a second bottom stream. The second bottom stream contains concentrated HMD containing DCH and optionally containing AMC, MPMD, or a combination thereof. The second distillation unit is configured to provide at least one of a second overhead stream and a side feed stream. The second overhead stream, the side feed stream, or a combination thereof is purified DCH. The purified DCH is at least 98.5% by weight DCH.

[0019] Various aspects of the methods and apparatus disclosed herein offer certain advantages over other methods used to recover purified materials (such as purified 2-methylglutaronitrile, hexamethyleneimine, or diaminocyclohexane) from crude mixtures. For example, in various aspects, the methods and apparatus of this disclosure can provide purified materials with higher purity (i.e., higher weight percentages of 2-methylglutaronitrile, hexamethyleneimine, or diaminocyclohexane) compared to other methods used to recover purified materials. In various aspects, the methods and apparatus of this disclosure can provide purified materials with lower concentrations of one or more impurities that may cause problems in subsequent processing steps compared to other methods used to recover purified materials. For example, in various aspects, the methods and apparatus of this disclosure can provide purified 2-methylglutaronitrile with lower concentrations of specific impurities (such as lower concentrations of 2-ethylbutadionitrile (ESN) and / or 2-cyanocyclopentylimine (CPI)) that may cause problems in subsequent processing steps compared to other methods used to recover 2-methylglutaronitrile. In all respects, the methods and apparatus of this disclosure reduce downtime due to blockages compared to other methods used to recover purified materials from crude mixtures, such as those used to recover 2-methylglutaronitrile, hexamethyleneimine, or diaminocyclohexane. Attached Figure Description

[0020] The accompanying drawings, which are not necessarily drawn to scale, generally illustrate the methods of the invention by way of example rather than by way of limitation.

[0021] Figure 1 It is a schematic diagram according to aspect 100 of this disclosure.

[0022] Figure 2 It is a schematic diagram according to aspect 200 of this disclosure.

[0023] Figure 3 It is a schematic diagram according to aspect 300 of this disclosure.

[0024] Figure 4 It is a schematic diagram according to aspect 400 of this disclosure.

[0025] Figure 5 This is a schematic diagram based on aspect 500 of this disclosure.

[0026] Figure 6 It is a schematic diagram according to aspect 600 of this disclosure. Detailed Implementation

[0027] Reference will now be made specifically to certain aspects of the disclosed subject matter. While the subject matter of the invention will be described in conjunction with the enumerated claims, it should be understood that the exemplary subject matter is not intended to limit the claims to the disclosed subject matter.

[0028] Throughout the document, values ​​expressed in this range format should be interpreted flexibly to include not only the values ​​explicitly listed as the upper and lower limits of the range, but also all individual values ​​or subranges covered within that range, just as if each value and subrange were explicitly listed. For example, the range “about 0.1% to about 5%” or “about 0.1% to 5%” should be understood to include not only about 0.1% to about 5%, but also the individual values ​​(e.g., 1%, 2%, 3%, and 4%) and subranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. Unless otherwise specified, the expression “about X to Y” has the same meaning as “about X to about Y”. Similarly, unless otherwise specified, the expression “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z”.

[0029] In this document, unless the context clearly indicates otherwise, the terms “a,” “an,” or “the / described” are used to include one or more. Unless otherwise specified, the term “or” is used to mean a non-exclusive “or.” The expressions “at least one of A and B” or “at least one of A or B” have the same meaning as “A, B, or A and B.” Furthermore, it should be understood that the wording or terminology used herein, unless otherwise defined, is for illustrative purposes only and not for limitation. Any use of section headings is intended to aid in reading the document and should not be construed as restrictive; information relating to a section heading may appear within or outside that particular section.

[0030] In the methods described herein, these actions can be performed in any order without departing from the principles of the invention, except where the timing or sequence of operations is explicitly stated. Furthermore, specified actions can be performed simultaneously unless the explicit language of the claims states that they can be performed individually. For example, performing the claimed action X and performing the claimed action Y can be performed simultaneously in a single operation, and the resulting process will fall within the literal scope of the claimed process.

[0031] As used herein, the term “about” may allow for a certain degree of fluctuation in a value or range, for example, within 10%, 5%, or 1% of the upper or lower limits of the value or range, and includes the exact value or range stated herein.

[0032] As used herein, the term “substantially” means most or most, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. As used herein, the term “substantially free” may mean having none or having trace amounts of material such that the amount of material present does not affect the material properties of the composition comprising the material, such that the composition is about 0% to about 5% by weight, or about 0% to about 1% by weight, or about 5% by weight or less, or less than, equal to or greater than about 4.5% by weight, 4% by weight, 3.5% by weight, 3% by weight, 2.5% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.9% by weight, 0.8% by weight, 0.7% by weight, 0.6% by weight, 0.5% by weight, 0.4% by weight, 0.3% by weight, 0.2% by weight, 0.1% by weight, 0.01% by weight, or about 0.001% by weight or less of the material. The term "substantially free" may mean having trace amounts such that the composition is about 0% to about 5% by weight, or about 0% to about 1% by weight, or about 5% by weight or less, or less than, equal to or greater than about 4.5% by weight, 4% by weight, 3.5% by weight, 3% by weight, 2.5% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.9% by weight, 0.8% by weight, 0.7% by weight, 0.6% by weight, 0.5% by weight, 0.4% by weight, 0.3% by weight, 0.2% by weight, 0.1% by weight, 0.01% by weight, or about 0.001% by weight or less, or about 0% by weight of material.

[0033] All publications mentioned in this specification, including non-patent literature (such as scientific journal articles), patent application publications, and patents, are incorporated by reference as if each publication were specifically and individually indicated as incorporated by reference.

[0034] It should be understood that the description herein is intended to be exemplary and not restrictive. Many other aspects will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the invention should be determined by reference to the appended claims and the full scope of their authorized equivalents. In the appended claims, the terms "comprising" and "wherein" are used as common English equivalents of the respective terms "including" and "wherein". Furthermore, the terms "first," "second," "third," etc., are used only as designations and are not intended to impose numerical requirements on their objects.

[0035] A method for recovering 2-methylglutaronitrile.

[0036] Hexamethylenediamine (HMD) is an important monomer in the manufacture of Nylon 66, and it is industrially produced by the hydrogenation of a six-carbon linear dinitrile (commonly known as adiponitrile (ADN)). Adiponitrile is synthesized from butadiene via a dihydrocyanation reaction with a cyanide source. This chemical process also produces other byproducts, such as six-carbon branched dinitriles, including 2-methylglutaronitrile (MGN) and 2-ethylbutadionitrile (ESN). Furthermore, some undesirable process conditions can also generate other byproducts and impurities.

[0037] Therefore, the crude adiponitrile stream may contain measurable amounts of branched dinitrile (e.g., ESN or MGN), various forms of trivalent and pentavalent phosphorus compounds, glycols, phenols, cresols, and catechols, as well as other substituted nitriles. This crude adiponitrile stream is purified to high-purity adiponitrile, and high-purity ADN is separated from the crude MGN by-product stream. During this step, most of these coproducts and impurities are concentrated in the crude MGN by-product stream and separated from the high-purity ADN. According to various aspects of the invention, the coproduct crude MGN by-product stream can be collected and further processed into a high-purity form (e.g., ≥99.1% by weight).

[0038] Hydrogenation of high-purity MGN is an important chemical process for preparing its corresponding diamine (i.e., 2-methylpentamethylenediamine or MPMD), which is used as a monomer in the preparation of various polyamides. Since impurities present in the crude MGN feed tend to deactivate the hydrogenation catalyst, it is desirable to remove them from the MGN feed. Furthermore, some of these impurities tend to interfere with certain downstream chemical processes during the hydrogenation formation of MPMD, thus adversely affecting the desired product yield and / or separation. Of particular importance in this regard is 2-ethylbutanedionitrile (ESN), which has a boiling point close to that of 2-methylglutaronitrile. Another process impurity is 2-cyanocyclopentadiene imine (CPI).

[0039] Various aspects of this disclosure provide a method for recovering and purifying 2-methylglutaronitrile from a crude mixture. The crude mixture may contain about 70 wt% to about 90 wt% of 2-methylglutaronitrile (e.g., less than or equal to 90 wt%, greater than or equal to 70 wt%, and less than, equal to, or greater than 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, or 89 wt%) and about 1 wt% to about 20 wt% of 2-ethylbutadionitrile (e.g., less than or equal to 20 wt%, greater than or equal to 1 wt%, and less than, equal to, or greater than 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%). 18% or 19% by weight), about 1% to 15% by weight of adiponitrile (e.g., less than or equal to 15% by weight, greater than or equal to 1% by weight, and less than, equal to or greater than 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight or 14% by weight), about 0.05% to about 5% by weight of 2-cyanocyclopentadiene imine (e.g., less than or equal to 5% by weight, greater than or equal to 0.05% by weight, and less than, equal to or greater than 0.1% by weight, 0.5% by weight, 1% by weight, 2% by weight, 3% by weight or 4% by weight), and about 0.01% to about 2% by weight of other impurities (e.g., less than or equal to 2% by weight, greater than or equal to 0.01% by weight, and less than, equal to or greater than 0.05% by weight, 0.1% by weight, 0.5% by weight, 1% by weight or 1.5% by weight).The crude mixture may also contain ≤5% by weight of phenol and cresol (e.g., less than or equal to 5% by weight, 4% by weight, 3% by weight, 2% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight, or about 0% by weight), ≤10% by weight of water (e.g., less than or equal to 9% by weight, 8% by weight, 7% by weight, 6% by weight, 5% by weight, 4% by weight, 3% by weight, 2% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight, or about 0% by weight), and ≤2% by weight of pentenoic acid (e.g., less than or equal to 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight). ≤0.2% by weight of borate esters or glycols (e.g., less than or equal to 0.2% by weight, 0.15% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight, or about 0% by weight), ≤100 ppm by weight of hydrogen cyanide (e.g., less than or equal to 100 ppm, 80 ppm, 60 ppm, 40 ppm, 20 ppm, 10 ppm or 5 ppm, or about 0 ppm), ≤100 ppm by weight of benzene (e.g., less than or equal to 100 ppm, 80 ppm, 60 ppm, 40 ppm, 20 ppm, 10 ppm or 5 ppm, or about 0 ppm), or combinations thereof, wherein the weight percentages are calculated based on the total mass of the crude mixture.

[0040] The method may include distilling a crude mixture in a first distillation unit to produce a first bottom stream and a first top stream. The first bottom stream may contain ≤1 wt% of 2-ethylbutadionitrile (e.g., less than or equal to 0.8 wt%, 0.6 wt%, 0.4 wt%, 0.2 wt%, or 0.1 wt%, or about 0 wt%) of the total first bottom stream mass. The first top stream may contain ≤1 wt% of adiponitrile (e.g., less than or equal to 0.8 wt%, 0.6 wt%, 0.4 wt%, 0.2 wt%, or 0.1 wt%, or about 0 wt%) of the total first top stream mass. The first distillation unit may have a head pressure in the range of 20 mmHg to 100 mmHg, or 40 mmHg to 60 mmHg, or less than or equal to 100 mmHg, greater than or equal to 20 mmHg, and less than, equal to, or greater than 30 mmHg, 35 mmHg, 40 mmHg, 45 mmHg, 50 mmHg, 55 mmHg, 60 mmHg, 65 mmHg, 70 mmHg, 80 mmHg, or 99 mmHg. Distilling the crude mixture in the first distillation unit may include introducing the crude mixture into the upper part of the first distillation unit. The first distillation unit may include two or more packed sections that together provide an amount equivalent to at least 30 to 80 total theoretical distillation stages, such as at least 30, 40, 45, 50, 55, 60, 65, or 70. The method may include passing process vapor from the top of a first distillation unit to a first condenser maintained at a condensation temperature and condensing the process vapor to provide liquid as a first overhead feed and to provide a first non-condensable vapor purging material. The top and bottom temperatures in the first distillation unit can be maintained within the ranges of 45°C-60°C (e.g., less than or equal to 60°C, greater than or equal to 45°C, and less than, equal to, or greater than 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, or 59°C) and 190°C-205°C (e.g., less than or equal to 205°C, greater than or equal to 190°C, and less than, equal to, or greater than 191°C, 192°C, 193°C, 194°C, 195°C, 196°C, 197°C, 198°C, 199°C, 200°C, 201°C, 202°C, 203°C, or 204°C), respectively.

[0041] The method may include distilling the first column bottom stream in a second distillation unit to produce a second column bottom stream, and producing at least one of a second column overhead stream and a side draw stream from the second distillation unit. The second column bottom stream may contain ≥80% of the 2-cyanocyclopentylimine content present in the crude mixture (e.g., greater than or equal to 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, or 99 wt%, or about 100 wt%). The second distillation unit may have a head pressure in the range of 20 mmHg to 100 mmHg, or 40 mmHg to 60 mmHg, or less than or equal to 100 mmHg, greater than or equal to 20 mmHg, and less than, equal to or greater than 30 mmHg, 35 mmHg, 40 mmHg, 45 mmHg, 50 mmHg, 55 mmHg, 60 mmHg, 65 mmHg, 70 mmHg, 80 mmHg or 90 mmHg. The second overhead feed stream and / or side take-off stream may contain ≥99.1% by weight of 2-methylglutaronitrile (e.g., greater than or equal to about 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9%, or about 100% by weight) and ≤0.5% by weight of 2-ethylbutadionitrile (e.g., less than or equal to 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.05%, or 0.01% by weight), or about 100% by weight of the total mass of the side take-off stream. The method may include obtaining a side feed stream from near the top section of the second distillation unit. Distilling the first column bottom stream in the second distillation unit may include introducing the first column bottom stream into the lower half of the second distillation unit. The second distillation unit may include two or more packing sections that together provide the equivalent of at least 10 to 50 total theoretical distillation stages, such as at least 10, 15, 20, 25, 30, 35, 40, or 45.The method may include passing process vapor from the top of a second distillation unit to a second condenser maintained at a condensation temperature and condensing the process vapor to provide liquid as a second overhead feed and to provide a second non-condensable vapor purging material. The top and bottom temperatures in the second distillation unit can be maintained within the ranges of 45℃-60℃ (e.g., less than or equal to 60℃, greater than or equal to 45℃, and less than, equal to or greater than 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, or 59℃) and 190℃-205℃ (e.g., less than or equal to 205℃, greater than or equal to 190℃, or less than, equal to or greater than 191℃, 192℃, 193℃, 194℃, 195℃, 196℃, 197℃, 198℃, 199℃, 200℃, 201℃, 202℃, 203℃, or 204℃), respectively.

[0042] The method may optionally include distilling at least one of the second column overhead stream and the side feed stream in a third distillation unit to produce a third column overhead stream and a third column bottom stream. In some aspects, optional distillation is not performed in the third column. In other aspects, optional distillation is performed in the third column, and the third column overhead stream may be purified 2-methylglutaronitrile. The third column overhead stream may contain ≤0.1 wt% of 2-cyanocyclopentylimine (e.g., less than or equal to 0.1 wt%, 0.08 wt%, 0.06 wt%, 0.04 wt%, 0.02 wt%, or 0.01 wt%, or about 0 wt%) of the total third column overhead stream mass. The third column bottom stream may contain ≤0.5 wt% of 2-ethylbutadionitrile (e.g., less than or equal to 0.5 wt%, 0.4 wt%, 0.3 wt%, 0.2 wt%, or 0.1 wt%, or about 0 wt%) of the total third column bottom stream mass. The third distillation unit may have a head pressure in the range of 10 mmHg to 80 mmHg, or 30 mmHg to 50 mmHg, or less than 80 mmHg, greater than 10 mmHg, and less than, equal to, or greater than 20 mmHg, 30 mmHg, 35 mmHg, 40 mmHg, 45 mmHg, 50 mmHg, 55 mmHg, 60 mmHg, 65 mmHg, 70 mmHg, 80 mmHg, or 90 mmHg. The top and bottom temperatures in the third distillation unit can be maintained within the ranges of 55°C-80°C (e.g., less than or equal to 80°C, greater than or equal to 55°C, and less than, equal to, or greater than 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, or 78°C) and 160°C-190°C (e.g., less than or equal to 190°C, greater than or equal to 160°C, and less than, equal to, or greater than 162°C, 164°C, 166°C, 168°C, 170°C, 172°C, 174°C, 176°C, or 178°C), respectively. At least one of the top feed stream and the side feed stream from the second distillation column may include introducing at least one of the top feed stream and the side feed stream into the lower half of the third distillation unit. The third distillation unit may include two or more packed sections that together provide an amount equivalent to at least 10 to 50 total theoretical distillation stages, such as at least 10, 15, 20, 25, 30, 35, 40, or 45. The method may include passing process vapor from the top of the third distillation unit to a third condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as a third overhead feed and to provide a third non-condensable vapor purge material.

[0043] Where, in the absence of optional distillation of at least one of the second overhead stream and the side feed stream in the third distillation unit, the second overhead stream, the side feed stream, or a combination thereof may be purified 2-methylglutaronitrile. The second overhead stream may be purified 2-methylglutaronitrile. The side feed stream may be purified 2-methylglutaronitrile. The combination of the second overhead stream and the side feed stream may be purified 2-methylglutaronitrile. Where, in the absence of optional distillation of at least one of the second overhead stream and the side feed stream in the third distillation unit, the third overhead stream may be purified 2-methylglutaronitrile. The purified 2-methylglutaronitrile (e.g., a side-draw stream, a second overhead stream, a combination of a side-draw stream and a second overhead stream, or a third overhead stream) can be ≥99.1% by weight of the total mass of purified 2-methylglutaronitrile (e.g., greater than or equal to 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, 99.95%, or 99.99%, or about 100% by weight) and ≤0.5% by weight of 2-ethylbutadiene (e.g., less than or equal to 0.5%, 0.45%, 0.4%, 0.35%, 0.3%, 0.25%, 0.2%, 0.15%, 0.1%). ≤0.2% by weight of adiponitrile (e.g., less than or equal to 0.2% by weight, 0.18% by weight, 0.15% by weight, 0.12% by weight, 0.1% by weight, 0.05% by weight, or 0.01% by weight, or about 0% by weight), ≤0.2% by weight of 2-cyanocyclopentadiene imine (e.g., less than or equal to 0.2% by weight, 0.18% by weight, 0.15% by weight, 0.12% by weight, 0.1% by weight, 0.05% by weight, or 0.01% by weight, or about 0% by weight), and ≤0.2% by weight of water (e.g., less than or equal to 0.2% by weight, 0.18% by weight, 0.15% by weight, 0.12% by weight, 0.1% by weight, 0.05% by weight, or 0.01% by weight, or about 0% by weight).

[0044] The method may include combining a first overhead stream, a second bottom stream, and a third bottom stream from each of the aspects in which an optional third distillation unit is present to form a tailings mixture. The tailings mixture may contain 1% to 30% by weight of 2-cyanocyclopentadiene imine (e.g., less than or equal to 30% by weight, greater than or equal to 1% by weight, and less than, equal to, or greater than 2% by weight, 4% by weight, 6% by weight, 8% by weight, 10% by weight, 12% by weight, 14% by weight, 16% by weight, 18% by weight, 20% by weight, 22% by weight, 24% by weight, 26% by weight, or 28% by weight) in the total tailings mixture mass. The method may include cooling the tailings mixture to a temperature of 40°C–60°C in a heat exchanger (e.g., less than or equal to 60°C, greater than or equal to 40°C, and less than, equal to, or greater than 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, or 58°C). The method may also include heating the tailings mixture by suitable conventional means. The method may also include adding water to the tailings mixture.

[0045] In all respects, the method can be carried out continuously in the event of less than 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2 or less than 1 flow interruption / annual operation from tailings mixture (e.g., blockage).

[0046] In aspects of the method excluding the optional third distillation, the method may further include collecting a portion of the first column bottom stream as a product stream. In aspects of the method including the optional third distillation, the method may further include collecting a portion of the first column bottom stream, a portion of the second column top stream, a portion of the side-drain stream, or a combination thereof as a product stream. The product stream may be 93 wt%–95 wt% of 2-methylglutaronitrile (e.g., less than or equal to 95 wt%, greater than or equal to 93 wt%, and less than, equal to, or greater than 93.2 wt%, 93.4 wt%, 93.6 wt%, 93.8 wt%, 94 wt%, 94.2 wt%, 94.4 wt%, 94.6 wt%, or 94.8 wt%) and 4 wt%–6 wt% of adiponitrile (e.g., less than or equal to 6 wt%, greater than or equal to 4 wt%, and less than, equal to, or greater than 4.2 wt%, 4.4 wt%, 4.6 wt%, or 4.8 wt%). The product stream can contain 1% by weight, 5% by weight, 5.2% by weight, 5.4% by weight, 5.6% by weight, or 5.8% by weight), less than 1% by weight of 2-ethylbutadionitrile (e.g., less than or equal to 0.9% by weight, 0.8% by weight, 0.6% by weight, 0.4% by weight, 0.2% by weight, 0.1% by weight, 0.01% by weight, or about 0% by weight), and 0.5% by weight to 1% by weight of 2-cyanocyclopentadiene imine (e.g., less than or equal to 1% by weight, greater than or equal to 0.5% by weight, and less than, equal to, or greater than 0.6% by weight, 0.7% by weight, 0.8% by weight, or 0.9% by weight). In each respect, the product stream can be hydrogenated in the presence of hydrogen and ammonia to hydrogenate 2-methylglutaronitrile and produce branched diamine methyl-pentamethylenediamine (MPMD). Hydrogenation can convert adiponitrile and any 2-ethylbutadionitrile into their respective diamines, namely hexamethylenediamine (HMD) and 1,3-pentanediamine (13PDA). Hydrogenation can convert 2-cyanocyclopentylimine into its corresponding amine, namely 2-(aminomethyl)-cyclopentylamine (AMC). The resulting hydrogenation product stream can be predominantly MPMD (e.g., 90 wt% or more of MPMD, such as less than or equal to 100 wt%, greater than or equal to 90 wt%, and less than, equal to, or greater than 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 99.9 wt%, or 99.99 wt%), wherein other components (e.g., HMD, 13PDA, AMC, or combinations thereof) constitute less than 10 wt% of the hydrogenation product stream (e.g., less than or equal to 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, 0.1 wt%, 0.05 wt%, or 0.01 wt%). The hydrogenation product stream can be optionally purified by stripping most of the HMD and 13PDA through distillation or other separation methods such as extraction, membrane separation, etc.Hydrogenated product streams or refined hydrogenated product streams can be semi-refined MPMD product streams, which are suitable for some industrial applications that are not very sensitive to AMC impurities in MPMD, such as epoxy curing, reactive coatings, and other applications where residual AMC will not cause problems.

[0047] Methods for recovering hexamethyleneimine.

[0048] Various aspects of this disclosure provide a method for recovering purified hexamethyleneimine (HMI) from a crude mixture, using a first distillation unit and a second distillation unit that are identical or similar to those described herein for recovering purified 2-methylglutaronitrile from a crude mixture. The first distillation unit for recovering purified HMI may be identical or similar to the first distillation unit for recovering purified 2-methylglutaronitrile in design, internal structure, construction, or combinations thereof. Similarly, the second distillation unit for recovering purified HMI may be identical or similar to the second distillation unit for recovering purified 2-methylglutaronitrile in design, internal structure, construction, or combinations thereof.

[0049] The crude mixture used in the method for recovering and purifying HMI may contain about 80% to about 90% by weight of HMI (e.g., less than or equal to 90% by weight, greater than or equal to 80% by weight, or less than, equal to or greater than 81% by weight, 82% by weight, 83% by weight, 84% by weight, 85% by weight, 86% by weight, 87% by weight, 88% by weight, or 89% by weight), about 5% to about 15% by weight of n-hexylamine (e.g., less than or equal to 15% by weight, greater than or equal to 5% by weight, or less than, equal to or greater than 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight, or 14% by weight), and about 0% to 5% by weight of water (e.g., less than or equal to 5% by weight, greater than or equal to 0% by weight, and less than, equal to or greater than 4% by weight). Cyclohexylamine (e.g., less than or equal to 5 wt%, greater than or equal to 0 wt%, and less than, equal to or greater than 4 wt%, 3 wt%, 2 wt%, 1.5 wt%, 1 wt%, 0.5 wt%, 0.1 wt%, 0.05 wt% or 0.01 wt%) from about 0 wt% to about 5 wt% (e.g., less than or equal to 5 wt%, greater than or equal to 0 wt%, and less than, equal to or greater than 4 wt%, 3 wt%, 2 wt%, 1.5 wt%, 1 wt%, 0.5 wt%, 0.1 wt%, 0.05 wt% or 0.01 wt%) and hexamethylenediamine (HMD) (e.g., less than or equal to 5 wt%, greater than or equal to 0 wt%, and less than, equal to or greater than 4 wt%, 3 wt%, 2 wt%, 1.5 wt%, 1 wt%, 0.5 wt%, 0.1 wt%, 0.05 wt% or 0.01 wt%) from about 0 wt% to about 5 wt% ...).

[0050] A method for recovering purified HMI may include distilling a first crude mixture in a first distillation unit to produce a first bottom stream and a first top stream, the first bottom stream containing concentrated HMI containing HMD, and the first top stream containing n-hexylamine and optionally water. The first distillation unit may have a head pressure maintained within the range of 400 mmHg to 500 mmHg, or about 425 mmHg to 450 mmHg, or less than or equal to 500 mmHg, greater than or equal to 400 mmHg, and less than, equal to, or greater than 405 mmHg, 410 mmHg, 415 mmHg, 420 mmHg, 425 mmHg, 430 mmHg, 435 mmHg, 440 mmHg, 445 mmHg, 450 mmHg, 455 mmHg, 460 mmHg, 465 mmHg, 470 mmHg, 475 mmHg, 480 mmHg, 485 mmHg, 490 mmHg, or 495 mmHg. The first distillation unit may have a base pressure maintained in the range of about 400 mmHg to 500 mmHg, or about 450 mmHg to 475 mmHg, or less than or equal to 500 mmHg, greater than or equal to 400 mmHg, and less than, equal to, or greater than 405 mmHg, 410 mmHg, 415 mmHg, 420 mmHg, 425 mmHg, 430 mmHg, 435 mmHg, 440 mmHg, 445 mmHg, 450 mmHg, 455 mmHg, 460 mmHg, 465 mmHg, 470 mmHg, 475 mmHg, 480 mmHg, 485 mmHg, 490 mmHg, or 495 mmHg. The head conditions of the first distillation unit can be maintained at approximately 100°C to 115°C, or less than or equal to 115°C, greater than or equal to 100°C, and less than, equal to, or greater than 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C, 110°C, 111°C, 112°C, 113°C, or 114°C. The base conditions of the first distillation unit can be maintained at approximately 110°C to 130°C, or less than or equal to 130°C, greater than or equal to 110°C, and less than, equal to, or greater than 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, or 128°C. Distilling the crude mixture in the first distillation unit may include introducing the crude mixture into the upper part of the first distillation unit. The first distillation unit may include two or more packing sections that together provide at least 50 total theoretical distillation stages, such as 50 to 80 stages, or less than or equal to 80, greater than or equal to 50, and less than, equal to, or greater than 55, 60, 65, 70, or 75 theoretical distillation stages.The method may include passing process vapor from the top of a first distillation unit to a first condenser maintained at a condensation temperature and condensing the process vapor to provide liquid as a first overhead feed and to provide a first non-condensable vapor purging material.

[0051] A method for recovering purified HMI may include distilling the first column bottoms stream in a second distillation unit to produce a second column bottoms stream containing concentrated HMD containing HMI. The second distillation unit may have a head pressure maintained within the range of approximately 100 mmHg to 200 mmHg, or approximately 145 mmHg to 155 mmHg, or less than or equal to 200 mmHg, greater than or equal to 100 mmHg, and less than, equal to, or greater than 105 mmHg, 110 mmHg, 115 mmHg, 120 mmHg, 125 mmHg, 130 mmHg, 135 mmHg, 140 mmHg, 145 mmHg, 150 mmHg, 155 mmHg, 160 mmHg, 165 mmHg, 170 mmHg, 175 mmHg, 180 mmHg, 185 mmHg, 190 mmHg, or 195 mmHg. The second distillation unit may have a base pressure maintained within the range of approximately 100 mmHg to 200 mmHg, or approximately 155 mmHg to 165 mmHg, or less than or equal to 200 mmHg, greater than or equal to 100 mmHg, and less than, equal to, or greater than 105 mmHg, 110 mmHg, 115 mmHg, 120 mmHg, 125 mmHg, 130 mmHg, 135 mmHg, 140 mmHg, 145 mmHg, 150 mmHg, 155 mmHg, 160 mmHg, 165 mmHg, 170 mmHg, 175 mmHg, 180 mmHg, 185 mmHg, 190 mmHg, or 195 mmHg. The head conditions of the second distillation unit can be maintained at approximately 80°C to 90°C, or less than or equal to 90°C, greater than or equal to 80°C, and less than, equal to, or greater than 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, or 89°C. The base conditions of the second distillation unit can be maintained at approximately 130°C to 140°C, or less than or equal to 140°C, greater than or equal to 130°C, and less than, equal to, or greater than 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, or 139°C. Distilling the bottom feed stream from the first column in the second distillation unit may include introducing the bottom feed stream from the first column into the upper part of the second distillation unit. The second distillation unit may include two or more packed sections that together provide at least 30 total theoretical distillation stages, or 30 to 60 stages, or less than or equal to 60, greater than or equal to 30, and less than, equal to, or greater than 35, 40, 45, 50, or 55 theoretical distillation stages. The method may include passing process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as a second overhead feed and to provide a second non-condensable vapor purge material.

[0052] The method may include obtaining at least one of a second overhead stream and a side feed stream from a second distillation unit. The method may include obtaining a side feed stream near the top section of the second distillation unit. The second overhead stream, the side feed stream, or a combination thereof may be purified HMI. The second overhead stream may be purified HMI. The side feed stream may be purified HMI. A combination of the second overhead stream and the side feed stream may be purified HMI. The purified HMI may be at least 99% by weight, such as 99% to 99.9% by weight, or 99% to 100% by weight, or less than or equal to 100% by weight, greater than or equal to 99% by weight, and less than, equal to, or greater than 99.1% by weight, 99.2% by weight, 99.3% by weight, 99.4% by weight, 99.5% by weight, 99.6% by weight, 99.7% by weight, 99.8% by weight, or 99% by weight. The purified HMI can be less than or equal to 0.40 wt% of cyclohexylamine (e.g., less than or equal to 0.4 wt%, 0.35 wt%, 0.3 wt%, 0.25 wt%, 0.2 wt%, 0.15 wt%, 0.1 wt%, 0.05 wt%, 0.01 wt%, or about 0 wt%), or less than or equal to 0.02 wt% of n-hexylamine (e.g., less than or equal to about 0.02 wt%, 0.01 wt%, 0.005 wt%, 0.001 wt%, or about 0 wt%). ), less than or equal to 0.07% by weight of water (e.g., less than or equal to about 0.07% by weight, 0.06% by weight, 0.05% by weight, 0.04% by weight, 0.03% by weight, 0.02% by weight, 0.01% by weight, 0.005% by weight, 0.001% by weight, or about 0% by weight) and less than or equal to 0.02% by weight of HMD (e.g., less than or equal to about 0.02% by weight, 0.01% by weight, 0.005% by weight, 0.001% by weight, or about 0% by weight).

[0053] In all aspects, purified HMI can have the same properties as those sold under the trade name Dytek. ® HMI amine has the same composition as HMI products commercially available from INVISTA. Purified HMI can be used in pharmaceuticals, textile chemicals, dyes, agricultural chemicals, corrosion inhibitors, inks, zeolite manufacturing, ore flotation, or rubber chemicals.

[0054] Method for the recovery of 1,2-diaminocyclohexane.

[0055] Various aspects of this disclosure provide a method for recovering purified 1,2-diaminocyclohexane (DCH) from a crude mixture using a first distillation unit and a second distillation unit that are identical or similar to those described herein for recovering purified 2-methylglutaronitrile from a crude mixture. The first distillation unit for recovering purified DCH may be identical or similar to the second distillation unit for recovering purified 2-methylglutaronitrile in design, internal structure, construction, or combinations thereof.

[0056] The crude mixture used in the method for recovering and purifying DCH may contain about 65% to about 80% DCH (e.g., less than or equal to 80% by weight, greater than or equal to about 65% by weight, or less than, equal to, or greater than 66% by weight, 67% by weight, 68% by weight, 69% by weight, 70% by weight, 71% by weight, 72% by weight, 73% by weight, 74% by weight, 75% by weight, 76% by weight, 77% by weight, 78% by weight, or 79% by weight), about 10% to about 20% hexamethylenediamine (H MD (e.g., less than or equal to 20% by weight, greater than or equal to 10% by weight, and less than, equal to, or greater than 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight, 18% by weight, or 19% by weight), and about 0% by about 5% by weight of hexamethyleneimine (HMI) (e.g., less than or equal to 5% by weight, greater than or equal to 0% by weight, and less than, equal to, or greater than 4% by weight, 3% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight). 2-(aminomethyl)cyclopentylamine (AMC) in amounts of about 0% to about 5% by weight (e.g., less than or equal to 5% by weight, greater than or equal to 0% by weight, and less than, equal to, or greater than 4% by weight, 3% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight, or 0.01% by weight), and 2-methylpentamethylenediamine (MPMD) in amounts of about 0% to about 5% by weight (e.g., less than, equal to, or greater than 4% by weight, 3% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight, or 0.01% by weight). The percentages are 5% or more by weight, greater than or equal to 0% by weight, and less than, equal to or greater than 4% by weight, 3% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight) and about 0% to about 2% by weight of other impurities containing n-hexylamine, cyclohexylamine or combinations thereof (e.g., less than or equal to 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight, or about 0% by weight).

[0057] A method for recovering purified DCH may include distilling a crude mixture in a first distillation unit to produce a first bottom stream and a first top stream, the first bottom stream containing concentrated DCH optionally containing HMD, AMC, MPMD, or a combination thereof, and the first top stream containing HMD and optionally containing AMC, MPMD, or a combination thereof. The first distillation unit may have a head pressure maintained between 700 mmHg and 850 mmHg, or about 760 mmHg, or about atmospheric conditions, or less than or equal to 850 mmHg, greater than or equal to 700 mmHg, and less than, equal to, or greater than 710 mmHg, 720 mmHg, 730 mmHg, 740 mmHg, 750 mmHg, 760 mmHg, 770 mmHg, 780 mmHg, 790 mmHg, 800 mmHg, 810 mmHg, 820 mmHg, 830 mmHg, or 840 mmHg. The first distillation unit may have a base pressure maintained between 700 mmHg and 850 mmHg, or about 760 mmHg, or about atmospheric conditions, or less than or equal to 850 mmHg, greater than or equal to 700 mmHg, and less than, equal to, or greater than 710 mmHg, 720 mmHg, 730 mmHg, 740 mmHg, 750 mmHg, 760 mmHg, 770 mmHg, 780 mmHg, 790 mmHg, 800 mmHg, 810 mmHg, 820 mmHg, 830 mmHg, or 840 mmHg. The head conditions of the first distillation unit may be maintained between about 130°C and 135°C, or less than or equal to 135°C, greater than or equal to 130°C, and less than, equal to, or greater than 131°C, 132°C, 133°C, or 134°C. The base conditions of the first distillation unit may be maintained at approximately 185°C to 200°C, or less than or equal to 200°C, greater than or equal to 185°C, and less than, equal to, or greater than 186°C, 187°C, 188°C, 189°C, 190°C, 191°C, 192°C, 193°C, 194°C, 195°C, 196°C, 197°C, 198°C, or 199°C. Distilling the crude mixture in the first distillation unit may include introducing the crude mixture into the lower half of the first distillation unit. The first distillation unit may include two or more packed sections that together provide the equivalent of at least 30 total theoretical distillation stages, or 30 to 80 stages, or less than or equal to 80 stages, greater than or equal to 30 stages, and less than, equal to, or greater than 35, 40, 45, 50, 55, 60, 65, 70, or 75 theoretical distillation stages. The method may include passing process vapor from the top of a first distillation unit to a first condenser maintained at a condensation temperature and condensing the process vapor to provide liquid as a first overhead feed and to provide a first non-condensable vapor purging material.

[0058] A method for recovering purified DCH may include distilling the first column bottoms stream in a second distillation unit to produce a second column bottoms stream containing concentrated HMD containing DCH and optionally AMC, MPMD, or a combination thereof. The second distillation unit may be maintained at a head pressure within the range of 100 mmHg to 200 mmHg, or 140 mmHg to 155 mmHg, or less than or equal to 200 mmHg, greater than or equal to 100 mmHg, and less than, equal to, or greater than 110 mmHg, 120 mmHg, 130 mmHg, 140 mmHg, 150 mmHg, 160 mmHg, 170 mmHg, 180 mmHg, or 190 mmHg. The head conditions of the second distillation unit can be maintained at approximately 140°C to 155°C, or less than or equal to 155°C, greater than or equal to 140°C, and less than, equal to, or greater than 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C, 150°C, 151°C, 152°C, 153°C, or 154°C. The base conditions of the second distillation unit can be maintained at approximately 145°C to 160°C, or less than or equal to 160°C, greater than or equal to 145°C, and less than, equal to, or greater than 146°C, 147°C, 148°C, 149°C, 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, 156°C, 157°C, 158°C, or 159°C. The second distillation unit may have a base pressure maintained within the range of approximately 150 mmHg to 250 mmHg, or 210 mmHg to 225 mmHg, or less than or equal to 250 mmHg, greater than or equal to 150 mmHg, and less than, equal to, or greater than 160 mmHg, 170 mmHg, 180 mmHg, 190 mmHg, 200 mmHg, 210 mmHg, 220 mmHg, 230 mmHg, or 240 mmHg. Distilling the bottom feed stream from the first column in the second distillation unit may include introducing the bottom feed stream from the first column into the lower half of the second distillation unit. The second distillation unit may include two or more packed sections that together provide an amount equivalent to at least 50 total theoretical distillation stages, or 50 to 100 stages, or less than or equal to 100 stages, greater than or equal to 50 stages, and less than, equal to, or greater than 55, 60, 65, 70, 75, 80, 85, 90, or 95 theoretical stages. The method may include passing process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as a second overhead feed and to provide a second non-condensable vapor purge material.

[0059] The method may include obtaining at least one of a second overhead stream and a side feed stream from a second distillation unit. The method may include obtaining a side feed stream near the top section of the second distillation unit. The second overhead stream, the side feed stream, or a combination thereof may be purified DCH. The second overhead stream may be purified DCH. The side feed stream may be purified DCH. A combination of the second overhead stream and the side feed stream may be purified DCH. The purified DCH may be at least 98.5% by weight, such as 98.5%-99.9% by weight, or 98.5%-100% by weight, or less than or equal to 100% by weight, greater than or equal to 98.5% by weight, or less than, equal to, or greater than 99% by weight, 99.2% by weight, 99.4% by weight, 99.6% by weight, 99.8% by weight, 99.9% by weight, or 99.99% by weight of DCH. The purified DCH can be less than or equal to 0.1 wt% of 2-methylpentamethylenediamine (e.g., less than or equal to 0.1 wt%, 0.05 wt%, or 0.01 wt%, or about 0 wt%), less than or equal to 0.1 wt% of hexamethylenediamine (e.g., less than or equal to 0.1 wt%, 0.05 wt%, or 0.01 wt%, or about 0 wt%), and less than or equal to 0.1 wt% of water (e.g., less than or equal to 0.1 wt%, 0.05 wt%, or 0.01 wt%, or about 0 wt%).

[0060] In all aspects, purified DCH can have the same properties as that sold under the trade name Dytek. ® DCH-99 amine has the same composition as DCH products commercially available from INVISTA. Purified DCH can be used as a chelating agent, a chain extender in polyurethanes and polyamides, an epoxy curing agent, a catalyst in polyurethane systems, and as a corrosion inhibitor and metalworking fluid.

[0061] Equipment used for the recovery of 2-methylglutaronitrile.

[0062] In various aspects, this disclosure provides an apparatus for recovering purified 2-methylglutaronitrile from a crude mixture. This apparatus can be any suitable apparatus capable of performing the methods described herein. The crude mixture may contain about 70% to about 90% by weight of 2-methylglutaronitrile (e.g., less than or equal to 90% by weight, greater than or equal to 70% by weight, and less than, equal to or greater than 71% by weight, 72% by weight, 73% by weight, 74% by weight, 75% by weight, 76% by weight, 77% by weight, 78% by weight, 79% by weight, 80% by weight, 81% by weight, 82% by weight, 83% by weight, 84% by weight, 85% by weight, 86% by weight, 87% by weight, 88% by weight, or 89% by weight), and about 1% to about 20% by weight of 2-ethylbutadionitrile (e.g., less than or equal to 20% by weight, greater than or equal to 1% by weight, and less than, equal to or greater than 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight). 18% or 19% by weight), about 1% to 15% by weight of adiponitrile (e.g., less than or equal to 15% by weight, greater than or equal to 1% by weight, and less than, equal to or greater than 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight or 14% by weight), about 0.05% to about 5% by weight of 2-cyanocyclopentadiene imine (e.g., less than or equal to 5% by weight, greater than or equal to 0.05% by weight, and less than, equal to or greater than 0.1% by weight, 0.5% by weight, 1% by weight, 2% by weight, 3% by weight or 4% by weight), and about 0.01% to about 2% by weight of other impurities (e.g., less than or equal to 2% by weight, greater than or equal to 0.01% by weight, and less than, equal to or greater than 0.05% by weight, 0.1% by weight, 0.5% by weight, 1% by weight or 1.5% by weight).The crude mixture may also contain ≤5% by weight of phenol and cresol (e.g., less than or equal to 5% by weight, 4% by weight, 3% by weight, 2% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight, or about 0% by weight), ≤10% by weight of water (e.g., less than or equal to 9% by weight, 8% by weight, 7% by weight, 6% by weight, 5% by weight, 4% by weight, 3% by weight, 2% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight, or about 0% by weight), and ≤2% by weight of pentenoic acid (e.g., less than or equal to 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight). ≤0.2% by weight of borate esters or glycols (e.g., less than or equal to 0.2% by weight, 0.15% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight, or about 0% by weight), ≤100 ppm by weight of hydrogen cyanide (e.g., less than or equal to 100 ppm, 80 ppm, 60 ppm, 40 ppm, 20 ppm, 10 ppm or 5 ppm, or about 0 ppm), ≤100 ppm by weight of benzene (e.g., less than or equal to 100 ppm, 80 ppm, 60 ppm, 40 ppm, 20 ppm, 10 ppm or 5 ppm, or about 0 ppm), or combinations thereof, wherein the weight percentages are calculated based on the total mass of the crude mixture.

[0063] The apparatus may include a first distillation unit configured to distill a crude mixture to produce a first bottom stream and a first top stream. The first distillation unit may be configured to operate at a head pressure in the range of 20 mmHg to 100 mmHg, 40 mmHg to 60 mmHg, or less than or equal to 100 mmHg, greater than or equal to 20 mmHg, and less than, equal to, or greater than 30 mmHg, 35 mmHg, 40 mmHg, 45 mmHg, 50 mmHg, 55 mmHg, 60 mmHg, 65 mmHg, 70 mmHg, 80 mmHg, or 99 mmHg. The first bottom stream may contain ≤1 wt% of 2-ethylbutadionitrile (e.g., less than or equal to 0.8 wt%, 0.6 wt%, 0.4 wt%, 0.2 wt%, or 0.1 wt%, or about 0 wt%) of the total first bottom stream mass. The first overhead stream may contain ≤1% by weight of adiponitrile (e.g., less than or equal to 0.8%, 0.6%, 0.4%, 0.2%, or 0.1%, or about 0% by weight) of the total first overhead stream mass. The first distillation unit may be configured to introduce a crude mixture into the upper portion of the first distillation unit. The first distillation unit may include two or more packed sections that together provide an amount equivalent to at least 30 to 80 total theoretical distillation stages, such as at least 30, 40, 45, 50, 55, 60, 65, or 70. The first distillation unit may be configured to pass process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the first overhead stream and to provide a first non-condensable vapor purge material. The first distillation unit can be configured to maintain the top and bottom temperatures within the ranges of 45°C-60°C (e.g., less than or equal to 60°C, greater than or equal to 45°C, and less than, equal to, or greater than 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, or 59°C) and 190°C-205°C (e.g., less than or equal to 205°C, greater than or equal to 190°C, and less than, equal to, or greater than 191°C, 192°C, 193°C, 194°C, 195°C, 196°C, 197°C, 198°C, 199°C, 200°C, 201°C, 202°C, 203°C, or 204°C), respectively.

[0064] The apparatus may include a second distillation unit configured to distill the bottom stream of the first column to produce a second bottom stream and a second top stream. The second distillation unit may be configured to operate at a head pressure within the range of 20 mmHg to 100 mmHg, or 40 mmHg to 60 mmHg, or less than or equal to 100 mmHg, greater than or equal to 20 mmHg, and less than, equal to, or greater than 30 mmHg, 35 mmHg, 40 mmHg, 45 mmHg, 50 mmHg, 55 mmHg, 60 mmHg, 65 mmHg, 70 mmHg, 80 mmHg, or 90 mmHg. The second column bottom stream may contain ≥80% of the 2-cyanocyclopentadiene imine present in the crude mixture (e.g., greater than or equal to 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, or 99 wt%, or about 100 wt%). The second distillation unit may be configured to provide a side feed stream from near the top section of the second distillation unit. The side-take stream may contain ≥99.1% by weight of 2-methylglutaronitrile (e.g., greater than or equal to about 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, or 99.9%, or about 100% by weight) and ≤0.5% by weight of 2-ethylbutadionitrile (e.g., less than or equal to 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.05%, or 0.01% by weight, or about 0% by weight) of the total mass of the side-take stream. The second distillation unit may contain ≤0.2 wt% adiponitrile (e.g., less than or equal to 0.2 wt%, 0.15 wt%, 0.1 wt%, 0.05 wt%, or 0.01 wt%, or about 0 wt%), ≤0.2 wt% 2-cyanocyclopentadiene imine (e.g., less than or equal to 0.2 wt%, 0.15 wt%, 0.1 wt%, 0.05 wt%, or 0.01 wt%, or about 0 wt%), and ≤0.2 wt% water (e.g., less than or equal to 0.2 wt%, 0.15 wt%, 0.1 wt%, 0.05 wt%, or 0.01 wt%, or about 0 wt%). The second distillation unit may be configured to introduce the bottom feed stream from the first column into the lower half of the second distillation unit. The second distillation unit may include two or more packed sections that together provide an amount equivalent to at least 10 to 50 total theoretical distillation stages, such as at least 10, 15, 20, 25, 30, 35, 40, or 45.The second distillation unit can be configured to pass the process vapor from the top of the second distillation unit to a second condenser that is maintained at the condensation temperature and condense the process vapor to provide liquid as a second overhead feed and to provide a second non-condensable vapor purging material. The second distillation unit can be configured to maintain the top and bottom temperatures within the ranges of 45°C-60°C (e.g., less than or equal to 60°C, greater than or equal to 45°C, and less than, equal to, or greater than 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, or 59°C) and 190°C-205°C (e.g., less than or equal to 205°C, greater than or equal to 190°C, or less than, equal to, or greater than 191°C, 192°C, 193°C, 194°C, 195°C, 196°C, 197°C, 198°C, 199°C, 200°C, 201°C, 202°C, 203°C, or 204°C).

[0065] The apparatus may optionally include a third distillation unit configured to distill at least one of the second overhead stream and the side feed stream to produce a third overhead stream and a third bottom stream. In some aspects of the apparatus, a third distillation unit is absent. In other aspects, a third distillation unit is present, and the third overhead stream is purified 2-methylglutaronitrile. The third distillation unit may be configured to operate at a head pressure ranging from 10 mmHg to 80 mmHg, or from 30 mmHg to 50 mmHg, or less than 80 mmHg, greater than 10 mmHg, and less than, equal to, or greater than 20 mmHg, 30 mmHg, 35 mmHg, 40 mmHg, 45 mmHg, 50 mmHg, 55 mmHg, 60 mmHg, 65 mmHg, 70 mmHg, 80 mmHg, or 90 mmHg. The third column overhead stream may contain ≤0.1 wt% of 2-cyanocyclopentadiene imine (e.g., less than or equal to 0.1 wt%, 0.08 wt%, 0.06 wt%, 0.04 wt%, 0.02 wt%, or 0.01 wt%, or about 0 wt%) of the total third column overhead stream mass. The third column bottom stream may contain ≤0.5 wt% of 2-ethylbutadionitrile (e.g., less than or equal to 0.5 wt%, 0.4 wt%, 0.3 wt%, 0.2 wt%, or 0.1 wt%, or about 0 wt%) of the total third column bottom stream mass. The third distillation unit can be configured to maintain its top and bottom temperatures within the ranges of 55°C–80°C (e.g., less than or equal to 80°C, greater than or equal to 55°C, and less than, equal to, or greater than 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, or 78°C) and 160°C–190°C (e.g., less than or equal to 190°C, greater than or equal to 160°C, and less than, equal to, or greater than 162°C, 164°C, 166°C, 168°C, 170°C, 172°C, 174°C, 176°C, or 178°C), respectively. The third distillation unit can be configured to introduce at least one of the top feed stream and the side draw stream from the second column into the lower half of the third distillation unit. The third distillation unit may include two or more packed sections that together provide an amount equivalent to at least 10 to 50 total theoretical distillation stages, such as at least 10, 15, 20, 25, 30, 35, 40, or 45. The third distillation unit may be configured to pass process vapor from the top of the third distillation unit column to a third condenser maintained at a condensation temperature and condense the process vapor to provide liquid as the third overhead feed and to provide a third non-condensable vapor purge material.

[0066] The apparatus may also include one or more flow channels configured to combine a first overhead stream, a second bottom stream, and an optional third bottom stream to form a tailings mixture containing 1% to 30% by weight of 2-cyanocyclopentadiene imine (e.g., less than or equal to 30% by weight, greater than or equal to 1% by weight, and less than, equal to, or greater than 2% by weight, 4% by weight, 6% by weight, 8% by weight, 10% by weight, 12% by weight, 14% by weight, 16% by weight, 18% by weight, 20% by weight, 22% by weight, 24% by weight, 26% by weight, or 28% by weight). The apparatus may also include a heat exchanger configured to cool the tailings mixture to a temperature of 40°C to 60°C (e.g., less than or equal to 60°C, greater than or equal to 40°C, and less than, equal to, or greater than 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, or 58°C). The equipment may also include a means of providing heat tracing to the tailings mixture using suitable conventional methods. The equipment may also include a device for adding water to the tailings mixture.

[0067] In the absence of an optional third distillation unit, the second overhead stream, side feed stream, or a combination thereof can be purified 2-methylglutaronitrile. The second overhead stream can be purified 2-methylglutaronitrile. The side feed stream can be purified 2-methylglutaronitrile. A combination of the second overhead stream and the side feed stream can be purified 2-methylglutaronitrile. In the presence of an optional third distillation unit, the third overhead stream can be purified 2-methylglutaronitrile. The purified 2-methylglutaronitrile (e.g., a side-draw stream, a second overhead stream, a combination of a side-draw stream and a second overhead stream, or a third overhead stream) can be ≥99.1% by weight of the total mass of purified 2-methylglutaronitrile (e.g., greater than or equal to 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, 99.95%, or 99.99%, or about 100% by weight) and ≤0.5% by weight of 2-ethylbutadiene (e.g., less than or equal to 0.5%, 0.45%, 0.4%, 0.35%, 0.3%, 0.25%, 0.2%, 0.15%, 0.1%). ≤0.2% by weight of adiponitrile (e.g., less than or equal to 0.2% by weight, 0.18% by weight, 0.15% by weight, 0.12% by weight, 0.1% by weight, 0.05% by weight, or 0.01% by weight, or about 0% by weight), ≤0.2% by weight of 2-cyanocyclopentadiene imine (e.g., less than or equal to 0.2% by weight, 0.18% by weight, 0.15% by weight, 0.12% by weight, 0.1% by weight, 0.05% by weight, or 0.01% by weight, or about 0% by weight), and ≤0.2% by weight of water (e.g., less than or equal to 0.2% by weight, 0.18% by weight, 0.15% by weight, 0.12% by weight, 0.1% by weight, 0.05% by weight, or 0.01% by weight, or about 0% by weight).

[0068] The equipment can operate continuously with fewer than 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 interruption (e.g., blockage) per year of flow interruption from the tailings mixture.

[0069] In various aspects of the apparatus excluding the optional third distillation unit, the apparatus may be configured to collect a portion of the first column bottom stream as a product stream. In various aspects of the apparatus including the optional third distillation unit, the apparatus may be configured to collect a portion of the first column bottom stream, a portion of the second column top stream, a portion of the side feed stream, or a combination thereof as a product stream. The product stream may be 93 wt%–95 wt% of 2-methylglutaronitrile (e.g., less than or equal to 95 wt%, greater than or equal to 93 wt%, and less than, equal to, or greater than 93.2 wt%, 93.4 wt%, 93.6 wt%, 93.8 wt%, 94 wt%, 94.2 wt%, 94.4 wt%, 94.6 wt%, or 94.8 wt%) and 4 wt%–6 wt% of adiponitrile (e.g., less than or equal to 6 wt%, greater than or equal to 4 wt%, and less than, equal to, or greater than 4.2 wt%, 4.4 wt%, 4.6 wt%, or 4.8 wt%). The product stream can contain 1% by weight, 5% by weight, 5.2% by weight, 5.4% by weight, 5.6% by weight, or 5.8% by weight), less than 1% by weight of 2-ethylbutadionitrile (e.g., less than or equal to 0.9% by weight, 0.8% by weight, 0.6% by weight, 0.4% by weight, 0.2% by weight, 0.1% by weight, 0.01% by weight, or about 0% by weight), and 0.5% by weight to 1% by weight of 2-cyanocyclopentadiene imine (e.g., less than or equal to 1% by weight, greater than or equal to 0.5% by weight, and less than, equal to, or greater than 0.6% by weight, 0.7% by weight, 0.8% by weight, or 0.9% by weight). In each respect, the product stream can be hydrogenated in the presence of hydrogen and ammonia to hydrogenate 2-methylglutaronitrile and produce branched diamine methyl-pentamethylenediamine (MPMD). Hydrogenation can convert adiponitrile and any 2-ethylbutadionitrile into their respective diamines, namely hexamethylenediamine (HMD) and 1,3-pentanediamine (13PDA). Hydrogenation can convert 2-cyanocyclopentylimine into its corresponding amine, namely 2-(aminomethyl)-cyclopentylamine (AMC). The resulting hydrogenation product stream can be predominantly MPMD (e.g., 90 wt% or more of MPMD, such as less than or equal to 100 wt%, greater than or equal to 90 wt%, and less than, equal to, or greater than 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 99.9 wt%, or 99.99 wt%), wherein other components (e.g., HMD, 13PDA, AMC, or combinations thereof) constitute less than 10 wt% of the hydrogenation product stream (e.g., less than or equal to 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, 0.1 wt%, 0.05 wt%, or 0.01 wt%).The hydrogenation product stream can be optionally purified by stripping most of the HMD and 13PDA through distillation or other separation methods, such as extraction, membrane separation, etc. The hydrogenation product stream or purified hydrogenation product stream can be a semi-purified MPMD product stream, which is suitable for some industrial applications that are not very sensitive to AMC impurities in MPMD, such as epoxy curing, reactive coatings, and other applications where residual AMC will not cause problems.

[0070] Equipment used for recycling hexamethyleneimine.

[0071] Various aspects of this disclosure provide an apparatus for recovering purified hexamethyleneimine (HMI) from a crude mixture, the apparatus using a first distillation unit and a second distillation unit identical or similar to those described herein for recovering purified 2-methylglutaronitrile from a crude mixture. The first distillation unit of the apparatus for recovering purified HMI may be identical or similar in design, internal structure, construction, or combinations thereof to the first distillation unit of the apparatus for recovering purified 2-methylglutaronitrile. Similarly, the second distillation unit of the apparatus for recovering purified HMI may be identical or similar in design, internal structure, construction, or combinations thereof to the second distillation unit of the apparatus for recovering purified 2-methylglutaronitrile.

[0072] The crude mixture in the apparatus used for recovering and purifying HMI may contain about 80% to about 90% by weight of HMI (e.g., less than or equal to 90% by weight, greater than or equal to 80% by weight, or less than, equal to, or greater than 81% by weight, 82% by weight, 83% by weight, 84% by weight, 85% by weight, 86% by weight, 87% by weight, 88% by weight, or 89% by weight), about 5% to about 15% by weight of n-hexylamine (e.g., less than or equal to 15% by weight, greater than or equal to 5% by weight, or less than, equal to, or greater than 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight, or 14% by weight), and about 0% to 5% by weight of water (e.g., less than or equal to 5% by weight, greater than or equal to 0% by weight, and less than, equal to, or greater than 4% by weight). Cyclohexylamine (e.g., less than or equal to 5 wt%, greater than or equal to 0 wt%, and less than, equal to or greater than 4 wt%, 3 wt%, 2 wt%, 1.5 wt%, 1 wt%, 0.5 wt%, 0.1 wt%, 0.05 wt% or 0.01 wt%) from about 0 wt% to about 5 wt% (e.g., less than or equal to 5 wt%, greater than or equal to 0 wt%, and less than, equal to or greater than 4 wt%, 3 wt%, 2 wt%, 1.5 wt%, 1 wt%, 0.5 wt%, 0.1 wt%, 0.05 wt% or 0.01 wt%) and hexamethylenediamine (HMD) (e.g., less than or equal to 5 wt%, greater than or equal to 0 wt%, and less than, equal to or greater than 4 wt%, 3 wt%, 2 wt%, 1.5 wt%, 1 wt%, 0.5 wt%, 0.1 wt%, 0.05 wt% or 0.01 wt%) from about 0 wt% to about 5 wt% ...).

[0073] The apparatus for recovering purified HMI may include a first distillation unit configured to distill a crude mixture to produce a first bottom stream and a first overhead stream, the first bottom stream containing concentrated HMI containing HMD, and the first overhead stream containing n-hexylamine and optionally water. The first distillation unit may have a head pressure maintained within the range of 400 mmHg to 500 mmHg, or about 425 mmHg to 450 mmHg, or less than or equal to 500 mmHg, greater than or equal to 400 mmHg, and less than, equal to, or greater than 405 mmHg, 410 mmHg, 415 mmHg, 420 mmHg, 425 mmHg, 430 mmHg, 435 mmHg, 440 mmHg, 445 mmHg, 450 mmHg, 455 mmHg, 460 mmHg, 465 mmHg, 470 mmHg, 475 mmHg, 480 mmHg, 485 mmHg, 490 mmHg, or 495 mmHg. The first distillation unit may have a base pressure maintained in the range of about 400 mmHg to 500 mmHg, or about 450 mmHg to 475 mmHg, or less than or equal to 500 mmHg, greater than or equal to 400 mmHg, and less than, equal to, or greater than 405 mmHg, 410 mmHg, 415 mmHg, 420 mmHg, 425 mmHg, 430 mmHg, 435 mmHg, 440 mmHg, 445 mmHg, 450 mmHg, 455 mmHg, 460 mmHg, 465 mmHg, 470 mmHg, 475 mmHg, 480 mmHg, 485 mmHg, 490 mmHg, or 495 mmHg. The head conditions of the first distillation unit can be maintained at approximately 100°C to 115°C, or less than or equal to 115°C, greater than or equal to 100°C, and less than, equal to, or greater than 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C, 110°C, 111°C, 112°C, 113°C, or 114°C. The base conditions of the first distillation unit can be maintained at approximately 110°C to 130°C, or less than or equal to 130°C, greater than or equal to 110°C, and less than, equal to, or greater than 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, or 128°C. The first distillation unit can be configured to introduce the crude mixture into the upper part of the first distillation unit. The first distillation unit may include two or more packing sections that together provide at least 50 total theoretical distillation stages, such as 50 to 80 stages, or less than or equal to 80, greater than or equal to 50, and less than, equal to, or greater than 55, 60, 65, 70, or 75 theoretical distillation stages.The first distillation unit may be configured to pass process vapor from the top of the first distillation unit to a first condenser that is maintained at a condensation temperature and condense the process vapor to provide liquid as a first overhead feed and to provide a first non-condensable vapor purging material.

[0074] The apparatus for recovering purified HMI may include a second distillation unit configured to distill a first bottom stream to produce a second bottom stream containing concentrated HMD containing HMI, wherein the second distillation unit is configured to provide at least one of a second overhead stream and a side feed stream. The second distillation unit may have a head pressure maintained within the range of approximately 100 mmHg to 200 mmHg, or approximately 145 mmHg to 155 mmHg, or less than or equal to 200 mmHg, greater than or equal to 100 mmHg, and less than, equal to, or greater than 105 mmHg, 110 mmHg, 115 mmHg, 120 mmHg, 125 mmHg, 130 mmHg, 135 mmHg, 140 mmHg, 145 mmHg, 150 mmHg, 155 mmHg, 160 mmHg, 165 mmHg, 170 mmHg, 175 mmHg, 180 mmHg, 185 mmHg, 190 mmHg, or 195 mmHg. The second distillation unit may have a base pressure maintained within the range of approximately 100 mmHg to 200 mmHg, or approximately 155 mmHg to 165 mmHg, or less than or equal to 200 mmHg, greater than or equal to 100 mmHg, and less than, equal to, or greater than 105 mmHg, 110 mmHg, 115 mmHg, 120 mmHg, 125 mmHg, 130 mmHg, 135 mmHg, 140 mmHg, 145 mmHg, 150 mmHg, 155 mmHg, 160 mmHg, 165 mmHg, 170 mmHg, 175 mmHg, 180 mmHg, 185 mmHg, 190 mmHg, or 195 mmHg. The head conditions of the second distillation unit can be maintained at approximately 80°C to 90°C, or less than or equal to 90°C, greater than or equal to 80°C, and less than, equal to, or greater than 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, or 89°C. The base conditions of the second distillation unit can be maintained at approximately 130°C to 140°C, or less than or equal to 140°C, greater than or equal to 130°C, and less than, equal to, or greater than 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, or 139°C. The second distillation unit can be configured to introduce the bottom feed stream from the first column into the upper part of the second distillation unit. The second distillation unit may include two or more packing sections that together provide at least 30 total theoretical distillation stages, or 30 to 60 stages, or less than or equal to 60, greater than or equal to 30, and less than, equal to, or greater than 35, 40, 45, 50, or 55 theoretical distillation stages.The second distillation unit can be configured to pass the process vapor from the top of the second distillation unit to a second condenser that is maintained at the condensation temperature and condense the process vapor to provide liquid as a second overhead feed and to provide a second non-condensable vapor purging material.

[0075] The second overhead stream, side feed stream, or a combination thereof can be purified HMI. The side feed stream can be removed from near the top section of the second distillation unit. The second overhead stream can be purified HMI. The side feed stream can be purified HMI. A combination of the second overhead stream and the side feed stream can be purified HMI. The purified HMI can be at least 99% by weight, such as 99% to 99.9% by weight, or 99% to 100% by weight, or less than or equal to 100% by weight, greater than or equal to 99% by weight, and less than, equal to, or greater than 99.1% by weight, 99.2% by weight, 99.3% by weight, 99.4% by weight, 99.5% by weight, 99.6% by weight, 99.7% by weight, 99.8% by weight, or 99% by weight. The purified HMI can be less than or equal to 0.40 wt% of cyclohexylamine (e.g., less than or equal to 0.4 wt%, 0.35 wt%, 0.3 wt%, 0.25 wt%, 0.2 wt%, 0.15 wt%, 0.1 wt%, 0.05 wt%, 0.01 wt%, or about 0 wt%), or less than or equal to 0.02 wt% of n-hexylamine (e.g., less than or equal to about 0.02 wt%, 0.01 wt%, 0.005 wt%, 0.001 wt%, or about 0 wt%). ), less than or equal to 0.07% by weight of water (e.g., less than or equal to about 0.07% by weight, 0.06% by weight, 0.05% by weight, 0.04% by weight, 0.03% by weight, 0.02% by weight, 0.01% by weight, 0.005% by weight, 0.001% by weight, or about 0% by weight) and less than or equal to 0.02% by weight of HMD (e.g., less than or equal to about 0.02% by weight, 0.01% by weight, 0.005% by weight, 0.001% by weight, or about 0% by weight).

[0076] In all aspects, purified HMI can have the same properties as those sold under the trade name Dytek. ® HMI amine has the same composition as HMI products commercially available from INVISTA. Purified HMI can be used in pharmaceuticals, textile chemicals, dyes, agricultural chemicals, corrosion inhibitors, inks, zeolite manufacturing, ore flotation, or rubber chemicals.

[0077] Equipment for the recovery of 1,2-diaminocyclohexane.

[0078] Various aspects of this disclosure provide an apparatus for recovering purified 1,2-diaminocyclohexane (DCH) from a crude mixture, the apparatus using the same or similar first and second distillation units as those described herein for recovering purified 2-methylglutaronitrile from a crude mixture. The first distillation unit of the apparatus for recovering purified DCH may be the same as or similar in design, internal structure, construction, or combinations thereof to the second distillation unit of the apparatus for recovering purified 2-methylglutaronitrile. Similarly, the second distillation unit of the apparatus for recovering purified DCH may be the same as or similar in design, internal structure, construction, or combinations thereof to the first distillation unit of the apparatus for recovering purified 2-methylglutaronitrile.

[0079] The crude mixture in the apparatus used for the recovery and purification of DCH may contain about 65% to about 80% DCH (e.g., less than or equal to 80% by weight, greater than or equal to about 65% by weight, or less than, equal to, or greater than 66% by weight, 67% by weight, 68% by weight, 69% by weight, 70% by weight, 71% by weight, 72% by weight, 73% by weight, 74% by weight, 75% by weight, 76% by weight, 77% by weight, 78% by weight, or 79% by weight), and about 10% to about 20% hexamethylenediamine (H2MDI). MD (e.g., less than or equal to 20% by weight, greater than or equal to 10% by weight, and less than, equal to, or greater than 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight, 18% by weight, or 19% by weight), and about 0% by about 5% by weight of hexamethyleneimine (HMI) (e.g., less than or equal to 5% by weight, greater than or equal to 0% by weight, and less than, equal to, or greater than 4% by weight, 3% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight). 2-(aminomethyl)cyclopentylamine (AMC) in amounts of about 0% to about 5% by weight (e.g., less than or equal to 5% by weight, greater than or equal to 0% by weight, and less than, equal to, or greater than 4% by weight, 3% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight, or 0.01% by weight), and 2-methylpentamethylenediamine (MPMD) in amounts of about 0% to about 5% by weight (e.g., less than, equal to, or greater than 4% by weight, 3% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight, or 0.01% by weight). The percentages are 5% or more by weight, greater than or equal to 0% by weight, and less than, equal to or greater than 4% by weight, 3% by weight, 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight) and about 0% to about 2% by weight of other impurities containing n-hexylamine, cyclohexylamine or combinations thereof (e.g., less than or equal to 2% by weight, 1.5% by weight, 1% by weight, 0.5% by weight, 0.1% by weight, 0.05% by weight or 0.01% by weight, or about 0% by weight).

[0080] The apparatus for recovering purified DCH may include a first distillation unit configured to distill a crude mixture to produce a first bottom stream and a first top stream, the first bottom stream containing concentrated DCH optionally containing HMD, AMC, MPMD, or a combination thereof, and the first top stream containing HMD and optionally containing AMC, MPMD, or a combination thereof. The first distillation unit may have a head pressure maintained between 700 mmHg and 850 mmHg, or about 760 mmHg, or about atmospheric conditions, or less than or equal to 850 mmHg, greater than or equal to 700 mmHg, and less than, equal to, or greater than 710 mmHg, 720 mmHg, 730 mmHg, 740 mmHg, 750 mmHg, 760 mmHg, 770 mmHg, 780 mmHg, 790 mmHg, 800 mmHg, 810 mmHg, 820 mmHg, 830 mmHg, or 840 mmHg. The first distillation unit may have a base pressure maintained between 700 mmHg and 850 mmHg, or about 760 mmHg, or about atmospheric conditions, or less than or equal to 850 mmHg, greater than or equal to 700 mmHg, and less than, equal to, or greater than 710 mmHg, 720 mmHg, 730 mmHg, 740 mmHg, 750 mmHg, 760 mmHg, 770 mmHg, 780 mmHg, 790 mmHg, 800 mmHg, 810 mmHg, 820 mmHg, 830 mmHg, or 840 mmHg. The head conditions of the first distillation unit may be maintained between about 130°C and 135°C, or less than or equal to 135°C, greater than or equal to 130°C, and less than, equal to, or greater than 131°C, 132°C, 133°C, or 134°C. The base conditions of the first distillation unit can be maintained at approximately 185°C to 200°C, or less than or equal to 200°C, greater than or equal to 185°C, and less than, equal to, or greater than 186°C, 187°C, 188°C, 189°C, 190°C, 191°C, 192°C, 193°C, 194°C, 195°C, 196°C, 197°C, 198°C, or 199°C. The first distillation unit can be configured to introduce a crude mixture into the lower half of the first distillation unit. The first distillation unit may include two or more packed sections that together provide the equivalent of at least 30 total theoretical distillation stages, or 30 to 80 stages, or less than or equal to 80 stages, greater than or equal to 30 stages, and less than, equal to, or greater than 35, 40, 45, 50, 55, 60, 65, 70, or 75 theoretical distillation stages. The first distillation unit may be configured to pass process vapor from the top of the first distillation unit to a first condenser that is maintained at a condensation temperature and condense the process vapor to provide liquid as a first overhead feed and to provide a first non-condensable vapor purging material.

[0081] The apparatus for recovering and purifying DCH may include a second distillation unit configured to distill the first column bottoms stream to produce a second column bottoms stream containing concentrated HMD containing DCH and optionally AMC, MPMD, or a combination thereof, wherein the second distillation unit is configured to provide at least one of a second column overhead stream and a side feed stream. The second distillation unit may be maintained at a head pressure within the range of 100 mmHg to 200 mmHg, or 140 mmHg to 155 mmHg, or less than or equal to 200 mmHg, greater than or equal to 100 mmHg, and less than, equal to, or greater than 110 mmHg, 120 mmHg, 130 mmHg, 140 mmHg, 150 mmHg, 160 mmHg, 170 mmHg, 180 mmHg, or 190 mmHg. The head conditions of the second distillation unit can be maintained at approximately 140°C to 155°C, or less than or equal to 155°C, greater than or equal to 140°C, and less than, equal to, or greater than 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C, 150°C, 151°C, 152°C, 153°C, or 154°C. The base conditions of the second distillation unit can be maintained at approximately 145°C to 160°C, or less than or equal to 160°C, greater than or equal to 145°C, and less than, equal to, or greater than 146°C, 147°C, 148°C, 149°C, 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, 156°C, 157°C, 158°C, or 159°C. The second distillation unit may have a base pressure maintained in the range of approximately 150 mmHg to 250 mmHg, or 210 mmHg to 225 mmHg, or less than or equal to 250 mmHg, greater than or equal to 150 mmHg, and less than, equal to, or greater than 160 mmHg, 170 mmHg, 180 mmHg, 190 mmHg, 200 mmHg, 210 mmHg, 220 mmHg, 230 mmHg, or 240 mmHg. The second distillation unit may be configured to introduce the bottom feed stream from the first column into the lower half of the second distillation unit. The second distillation unit may include two or more packed sections that together provide the equivalent of at least 50 total theoretical distillation stages, or 50 to 100 stages, or less than or equal to 100 stages, greater than or equal to 50 stages, and less than, equal to, or greater than 55, 60, 65, 70, 75, 80, 85, 90, or 95 theoretical stages. The second distillation unit can be configured to pass the process vapor from the top of the second distillation unit to a second condenser that is maintained at the condensation temperature and condense the process vapor to provide liquid as a second overhead feed and to provide a second non-condensable vapor purging material.

[0082] The second overhead stream, side feed stream, or a combination thereof may be purified DCH. The side feed stream may be obtained from near the top section of the second distillation unit. The second overhead stream, side feed stream, or a combination thereof may be purified DCH. The second overhead stream may be purified DCH. The side feed stream may be purified DCH. A combination of the second overhead stream and the side feed stream may be purified DCH. The purified DCH may be at least 98.5% by weight, such as 98.5%-99.9% by weight, or 98.5%-100% by weight, or less than or equal to 100% by weight, and greater than or equal to 98.5% by weight, or less than, equal to, or greater than 99% by weight, 99.2% by weight, 99.4% by weight, 99.6% by weight, 99.8% by weight, 99.9% by weight, or 99.99% by weight. The purified DCH can be less than or equal to 0.1 wt% of 2-methylpentamethylenediamine (e.g., less than or equal to 0.1 wt%, 0.05 wt%, or 0.01 wt%, or about 0 wt%), less than or equal to 0.1 wt% of hexamethylenediamine (e.g., less than or equal to 0.1 wt%, 0.05 wt%, or 0.01 wt%, or about 0 wt%), and less than or equal to 0.1 wt% of water (e.g., less than or equal to 0.1 wt%, 0.05 wt%, or 0.01 wt%, or about 0 wt%).

[0083] In all aspects, purified DCH can have the same properties as that sold under the trade name Dytek. ® DCH-99 amine has the same composition as DCH products commercially available from INVISTA. Purified DCH can be used as a chelating agent, a chain extender in polyurethanes and polyamides, an epoxy curing agent, a catalyst in polyurethane systems, and as a corrosion inhibitor and metalworking fluid.

[0084] Example

[0085] Various aspects of this disclosure can be better understood by referring to the following embodiments, which are provided by way of example. This disclosure is not limited to the embodiments given herein.

[0086] Material names and abbreviations: adiponitrile (ADN); 2-(aminomethyl)-cyclopentanylamine (AMC); 2-cyanocyclopentylimine (CPI); 2-ethylbutadienenitrile (ESN); hexamethylenediamine (HMD); 2-methylglutaronitrile (MGN); 2-methyl-pentamethylenediamine (MPMD); 3-methylpiperidine (MPP or 3MP); 1,3-pentanediamine (13PDA); hexamethyleneimine (HMI); 1,2-diaminocyclohexane (DCH).

[0087] Unless otherwise stated, all ppm and % values ​​are by weight.

[0088] One Torr, a unit of pressure measurement, is equal to 1 mmHg. One Psi of absolute pressure (Psia) is equal to 51.715 mmHg.

[0089] Example 1. (Comparative Example)

[0090] Figure 1 This is a schematic diagram of the double distillation column apparatus used in this comparative example. In this comparative example, the following is implemented: Figure 1 The distillation column system 100 shown and similar to the method described in WO2014210191A1.

[0091] exist Figure 1 In this process, feed stream 3 contains (by weight) approximately 80% MGN, approximately 10% ESN, approximately 2%-5% ADN, approximately 0.5% CPI, approximately 3%-3.5% other nitriles, and the balance <1% (combined) of other volatile impurities such as trivalent and pentavalent phosphorus substances, glycols, phenols, cresols, catechols, trace amounts of HCN, and benzene. Feed stream 3 is fed into the first distillation column 111. The head pressure of column 111 is maintained at approximately 50 mmHg (0.97 Psia), and the top / bottom temperature is maintained at approximately 50°C / 200°C. Column 111 distills the feed and concentrates the light components and most of the ESN at the top. The top condenser ( Figure 1 (Not shown) The overhead product of column 111 is condensed to obtain approximately 30%-40% of each ESN and MGN, and a total of approximately 20%-30% of light impurities, as overhead stream 7. The non-condensable components from the condenser of column 111 are purged with an inert gas (nitrogen) and allowed to flow to the exhaust manifold for disposal. Bottom stream 5 of column 111 may contain approximately 93%-95% MGN, 4%-6% ADN, <1% ESN, and 0.5%-1% CPI.

[0092] The bottom feed stream 5 is fed into the second distillation column 121. The head pressure of column 121 is maintained at approximately 50 mmHg (0.97 Psia), and the top / bottom temperature is maintained at approximately 50°C / 200°C. Column 121 distills the bottom feed stream 5 and concentrates the MGN overhead product. The overhead condenser (…) Figure 1 (Not shown) The overhead product of column 121 is condensed to produce MGN with a purity of at least 99.1%, ESN of approximately <5000 ppm, ADN of <1000 ppm, and CPI of approximately 0.5%-0.6%, as overhead stream 9. The non-condensable components in the overhead product of column 121 are purged with an inert gas (nitrogen) and allowed to flow to an exhaust manifold for disposal. Bottom stream 11 of column 121 may contain most of the ADN present in feed stream 3, as well as some MGN and residual CPI.

[0093] When MGN purification was performed using the method of WO2014210191A1 in this embodiment, the CPI level in the purified MGN product (i.e., the overhead stream 9) did not decrease to below 5000 ppm (by weight).

[0094] When the refined MGN is further hydrogenated to MPMD, the CPI in MGN is completely converted into its reducing amination intermediate 2-(aminomethyl)-cyclopentanamine (AMC). AMC is difficult to remove from the MPMD product. The resulting refined MPMD product contains a high level of AMC and is therefore unsuitable for many commercial end-use applications, such as the manufacture of vitamin B3 (niacin) and fiber applications.

[0095] It was observed that the bottom flow 11 of the second tower exhibited significant flow difficulties. It was noted that the flow lines for the bottom flow 11 were frequently blocked. This necessitated frequent shutdowns to clear the lines. These shutdowns were undesirable, laborious, and costly, as they resulted in production losses.

[0096] Example 2.

[0097] Figure 2 A schematic diagram of aspect 200 is shown, which is an improvement on the aspect described in embodiment 1.

[0098] exist Figure 2 In this process, feed stream 32 contains (by weight) approximately 85%-87% MGN, approximately 5%-8% ESN, approximately 3%-5% ADN, approximately 0.5% CPI, approximately 1%-2% other nitriles, and the balance <1% (combined) of other volatile impurities such as trivalent and pentavalent phosphorus substances, glycols, phenols, cresols, catechols, trace amounts of HCN, and benzene. Feed stream 32 is fed to the first distillation column 211, which operates similarly to column 111 in Example 1. The head pressure of column 211 is maintained at approximately 50 mmHg (0.97 Psia), and the top / bottom temperature is maintained at approximately 50°C / 198°C. Column 211 distills the feed and concentrates the lighter components and most of the ESN at the top. The top condenser ( Figure 2 (Not shown in the image) The overhead product of column 211 is condensed to obtain approximately 30%-35% ESN, 50%-55% MGN, and a total of approximately 15%-20% lighter impurities, as overhead stream 72. Optionally, in cases such as transient, start-up, and production variation modes, a portion of stream 163 (e.g., Figure 2 (As shown by the dashed path in the diagram) can be recycled back to column 211. The non-condensable components from the condenser of column 211 are purged with an inert gas (nitrogen) and directed to the exhaust manifold for disposal. The bottom stream 52 of column 211 may contain approximately 93%-95% MGN, 4%-6% ADN, <1% ESN, and 0.5%-1% CPI.

[0099] The bottom feed stream 52 is fed into the second distillation column 221, which operates similarly to column 121 in Example 1. The head pressure of column 221 is maintained at approximately 50 mmHg (0.97 Psia), and the top / bottom temperature is maintained at approximately 50°C / 195°C. Column 221 distills the bottom feed stream 52 and concentrates the MGN overhead product. The overhead condenser (…) Figure 2 (Not shown) The overhead product of column 221 is condensed to produce MGN with a purity of at least 99.1%, ESN of approximately <5000 ppm, ADN of <1000 ppm, and CPI of approximately 0.5%-0.6%, as overhead stream 92. The non-condensable components in the overhead product of column 221 are purged with an inert gas (nitrogen) and allowed to flow to an exhaust manifold for disposal. Bottom stream 112 of column 221 may contain most of the ADN present in feed stream 32, as well as some residual MGN and CPI.

[0100] Optionally, a side feed stream 97 rich in MGN can be obtained near the top of tower 221. The side feed recovers high-purity MGN. Although a liquid side feed is used, a vapor side feed can also be used. In this embodiment, the side feed stream 97 may contain ESN with a purity of at least 99.1%, about <4000 ppm, ADN <1000 ppm, CPI about <1500 ppm, and water about <1500 ppm. By using part or all of the side feed stream (e.g. Figure 2 (As shown by the dashed path 99 in the diagram) is conveyed together with the top feed stream 92 to achieve further MGN purification.

[0101] The overhead feed stream 92 from column 221 is fed into the lower section of third distillation column 241, which comprises two or more packed sections. The head pressure of column 241 is maintained at approximately 40 mmHg (approximately 0.77 Psia), and the overhead / bottom temperature is maintained at approximately 70°C / 177°C. Column 241 distills the feed and concentrates the MGN overhead product. The overhead condenser (…) Figure 2 (Not shown) The overhead product of column 241 is condensed to produce MGN with a purity of at least 99.5%, ESN of approximately <5000 ppm, ADN of <1000 ppm, and CPI of <1000 ppm, as overhead stream 152. The non-condensable components in the overhead product of column 241 are purged with an inert gas (nitrogen) and allowed to flow to an exhaust manifold for disposal. Bottom stream 154 of column 241 may contain ADN, as well as some MGN and CPI.

[0102] When using Figure 2 When MGN is purified using a three-tower configuration, the CPI level in the purified MGN product (i.e., the overhead stream 152) is reduced to below 1000 ppm (by weight).

[0103] exist Figure 2 In the distillation system 200 shown, the overhead stream 72 of column 211, the bottom stream 112 of column 221, and the bottom stream 154 of column 241 are combined and flow together as tail stream 156 to heat exchanger 231. The combined tail stream 156 contains (by weight) approximately 50%-60% MGN, 18%-25% ESN, 10%-15% ADN, <10% other organic impurities in total, and approximately 1%-2% CPI. Tail stream 156 is cooled to 50°C-65°C in heat exchanger 231 and is conveyed as cooled tail stream 161 for disposal. Optionally, the bottom stream 158 of column 241 ( Figure 2 The dashed path in the diagram can bypass the heat exchange device 231.

[0104] In this embodiment, when the three streams (i.e., streams 72, 112, and 154) are combined, the tail stream 156 experiences no flow difficulties before or after the heat exchanger 231. No blockages or obstructions were observed in the flow lines. Advantageously, the distillation system 200 was observed to be able to operate continuously to purify MGN without any interruption or downtime. Compared to Example 1, the purified MGN product contained a lower level of CPI impurities.

[0105] Example 3.

[0106] Figure 3 A schematic diagram of the distillation system 300 used in this embodiment is shown. The crude MGN feed stream 33 contains approximately 11% ESN, 5% ADN, approximately 1.5% CPI, the balance MGN, and <5000 ppm (combined) of other volatile impurities such as trivalent and pentavalent phosphorus substances, glycols, phenols, cresols, and catechols.

[0107] Crude MGN feed 33 is fed into the first column 311, which contains five structured packed beds and provides the equivalent of at least 50 theoretical distillation stages. Crude feed 33 enters between the top two packed beds. The product exiting column 311 contains MGN and concentrated ESN in the range of 10%–90% ESN. This is then condensed in the top condenser (…). Figure 3 In column 311 (not shown), the product vapor at the top of column 311 is condensed, some of which is removed as the first overhead stream 73, and some of which is used for column reflux (not shown). Column 311 is typically operated at a head pressure of approximately 50 mmHg, with an operating range of 20 mmHg–100 mmHg.

[0108] The bottom of the first column 311 is equipped with a forced circulation reboiler to minimize the risk of fouling. A thermosiphon reboiler can also be used. The bottom stream 53 of the first column 311 contains most of MGN, as well as ADN, CPI, and less than 4000 ppm of ESN. This bottom stream 53 of the first column 311 is fed to the second column 321 for further purification.

[0109] The second column 321 contains four layers of structured packed beds, with the feed entering above the bottom bed. A contact condenser is located in the column, and a fifth layer of structured packed bed is located at the top of column 321. The second column 321 typically operates at a head pressure of approximately 40 mmHg, with an operating range of 20 mmHg–100 mmHg.

[0110] The overhead vapor exiting the top of the second column 321 is condensed and returned to the second column 321 as reflux (not shown). Non-condensable components are delivered as tail gas 93 to the exhaust manifold for disposal.

[0111] A purified MGN product is obtained from the second column 321 via a side feed stream 95 taken near the top of the column. The side feed recovers MGN with very high purity. A liquid side feed is used; however, a vapor side feed can also be used.

[0112] The bottom of the second column 321 is equipped with a forced circulation reboiler to minimize the risk of scaling. A thermosiphon reboiler can also be used. The bottom stream 113 of the second column 321 contains MGN, ADN, and CPI.

[0113] The top feed stream 73 of the first tower 311 is combined with the bottom feed stream 113 of the second tower 321, and the combined tail stream 115 flows to the heat exchanger 331. The heat exchanger 331 cools the combined tail stream 115 to a temperature range of 45°C-65°C. The cooled combined tail stream 117 is then conveyed for disposal, such as for incineration in a boiler.

[0114] In this embodiment, a refined MGN product with a purity of at least 99.1% (i.e., side stream 95) was obtained, containing approximately <4000 ppm ESN, <1000 ppm ADN, approximately <1200 ppm CPI and <1200 ppm moisture.

[0115] A CPI reduction of over 90% was observed in this embodiment, i.e., from 1.5% in the crude MGN feed 33 to <1200 ppm in the refined MGN product stream 95. Such a very low level of CPI in the refined MGN stream is highly desirable for commercial success.

[0116] In this embodiment, when the two streams (i.e., streams 73 and 113) are merged, the tail stream 115 experiences no flow difficulties before or after the heat exchanger 331. No blockages or obstructions were observed in the flow lines. Advantageously, the distillation system 300 was observed to be able to operate continuously to purify MGN without any interruption or downtime. Compared to Example 1, the purified MGN product contained a lower level of CPI impurities.

[0117] Example 4.

[0118] The crude MGN feed stream contains approximately 85% MGN, 10% ESN, 3% ADN, approximately 1.5% CPI, and <5000 ppm (combined) of other process impurities such as trivalent and pentavalent phosphorus substances, glycols, phenols, cresols, and catechols. See Example 3 and... Figure 3 The crude feed stream is processed in a dual-tower distillation system. The crude feed 33 is effectively fractionated in the first tower 311 to a first tower bottom stream 53 rich in MGN, containing approximately 90% MGN, <20% ADN, <0.5% ESN, and approximately 2%-3% CPI. The overhead vapor from the first tower is condensed to obtain a first tower overhead liquid stream 73, which concentrates the ESN to obtain an ESN:MGN ratio of approximately 30:70. The first tower overhead vapor stream also concentrates other incoming impurities such as trivalent and pentavalent phosphorus substances, glycols, phenols, cresols, and catechols. The non-condensable overhead gaseous stream is conveyed to an exhaust manifold for disposal.

[0119] The bottom stream 53 of the first column is fed into the second column 321. The side stream 95, taken from near the top section of the second column 321, is refined MGN product with a purity of at least 99.1%, containing approximately <4000 ppm ESN, <1000 ppm ADN, approximately <1200 ppm CPI, and <1200 ppm water. The bottom stream 113 of the second column contains accumulated CPI, ADN, and some MGN. The top liquid stream 73 of the first column is combined with the bottom stream 113 of the second column, cooled in a heat exchanger 331, and then fed to a boiler for combustion. The flow of stream 115 is continuous, without flow line blockage or process interruption.

[0120] Example 5.

[0121] The dual-tower distillation system of Example 3 is repeated, except that the liquid stream 73 from the first tower is not combined with the bottom stream 113 from the second tower before being conveyed for disposal. The CPI concentration in the bottom stream 113 from the second tower varies between 5% and 20% (by weight) of the total volume. This stream can cause flow line blockage, further restricting flow. Due to these frequent process interruptions, process productivity is reduced. Frequent equipment and line cleaning is required. The process cannot be operated continuously.

[0122] Example 6.

[0123] The purified MGN product of Comparative Example 1 was hydrogenated in the presence of hydrogen and ammonia to produce its corresponding branched diamine, 2-methyl-pentamethylenediamine (MPMD). CPI present in the hydrogenation feed was converted to its corresponding amine, termed 2-(aminomethyl)-cyclopentanamine (AMC). Separating AMC from the hydrogenation product was not straightforward. High levels of CPI in the purified MGN product, which served as the feed for the hydrogenation step, were undesirable.

[0124] Example 7.

[0125] The purified MGN product of Example 3 was hydrogenated in the presence of hydrogen and ammonia to produce its corresponding branched diamine, 2-methyl-pentamethylenediamine (MPMD). This purified MGN product containing <1200 ppm CPI was hydrogenated to produce MPMD containing very low levels of 2-(aminomethyl)-cyclopentanamine (AMC). It is desirable to produce MPMD containing very low levels of AMC.

[0126] Example 8.

[0127] Figure 4 A schematic diagram of a distillation unit 400, as used in Example 3, is shown. This distillation unit includes, for example... Figure 3 The second distillation unit 321 is shown. In Figure 4 The main unit components are shown, but auxiliary components such as flow meters, flow / temperature / pressure control equipment, online filters, and bypass lines are not shown.

[0128] exist Figure 4In this unit, vertical distillation unit 401 accommodates more than two gas-liquid contact sections, some of which are designated 403, and provides at least 30 theoretical distillation stages for separation. Other suitable physical designs and / or media for gas-liquid contact can also be used in unit 401. Some non-limiting examples are bubble cap tray sections, sieve tray sections, structured / random packing sections, etc. Unit 401 is equipped with a side-drain pump unit 404, a side-drain heat exchange unit 405, a reflux liquid jet unit 406, a bottom ejector 407, a reboiler feed pump 408, a reboiler unit 409, and a bottom outflow pump unit 410.

[0129] Distillation feed 471 may be generated in steps prior to unit 401, such as by means of... Figure 3 The first distillation unit 311 is shown. Feed 471 may contain MGN, as well as ADN, CPI, and ESN less than 4000 ppm. Feed 471 is pumped via feed pump unit 402, and pressurized feed 472 is introduced into the lower half of unit 401. Figure 4 As an illustration, the feed introduction is shown between the two lower packing sections.

[0130] Conditions in unit 401 are maintained to concentrate MGN at the top of the column when gas-liquid contact is achieved in the packed section. The top section of unit 401 is equipped with a liquid collection stage from which the accumulated liquid can be extracted as a side-draw stream 473. Side-draw stream 473 is pumped via side-draw pump unit 404 to side-draw heat exchanger unit 405 for cooling. A portion of the discharge from side-draw pump unit 404 can be returned to unit 401, which is shown as return stream 474.

[0131] A portion of the cooled side feed stream 475 is returned to unit 401 as a return liquid stream 477. The return liquid stream 477 is uniformly distributed across the flow area of ​​unit 401 using a return liquid injection unit 406. The remaining cooled side feed stream 476 is refined MGN product with a purity of at least 99.1%, containing approximately <4000 ppm ESN, <1000 ppm ADN, approximately <1200 ppm CPI, and <1200 ppm water by total mass.

[0132] The bottom liquid flow 479 of unit 401 is pumped to reboiler unit 409 as reboiler feed flow 480 via reboiler feed pump 408. Liquid boiling energy is provided in reboiler unit 409, and the boiling vapor flow 481 is returned to unit 401 via bottom ejector 407. The return liquid flow 477 and the boiling vapor flow 481 are maintained to provide sufficient hydraulic load and counter-current gas-liquid flow rate in unit 401. Care should be taken not to overload unit 401, as this may result in liquid overflow or drying out of the separation space.

[0133] A portion of the bottom liquid in unit 401 is pumped out as bottom extract stream 482 via bottom extract pump 410. Bottom extract stream 482 contains MGN, ADN, and CPI. This stream is conveyed for safe disposal, which is equivalent to... Figure 3 The feed stream marked 113. Non-condensable tail gas stream 478 is drawn from the top of unit 401 and delivered to the exhaust manifold, which is equivalent to... Figure 3 The exhaust gas marked as 93.

[0134] Unit 401 recovers MGN to a purity of at least 99.1% (by weight), containing approximately <4000 ppm ESN, <1000 ppm ADN, approximately <1200 ppm CPI, and <1200 ppm water by total mass. This high-purity MGN is an ideal feedstock for subsequent hydrogenation to its diamine MPMD.

[0135] Example 9 .

[0136] Referring to the description in Example 2 and Figure 2 The process, schematically illustrated, involves a bottom feed stream 52 from column 211 containing approximately 93%-95% MGN, 4%-6% ADN, <1% ESN, and 0.5%-1% CPI. This MGN-containing stream 52 is cooled and hydrogenated in the presence of hydrogen and ammonia to produce its corresponding branched diamine, 2-methyl-pentamethylenediamine (MPMD). The ADN and ESN present in the feed are converted into their corresponding diamines, hexamethylenediamine (HMD) and 1,3-pentanediamine (13PDA). Residual CPI impurities are hydrogenated to their corresponding amine, 2-(aminomethyl)-cyclopentanamine (AMC).

[0137] The hydrogenation product mainly contains MPMD, with other components (HMD, 13PDA, AMC) accounting for <10% by weight of the total feed. The crude hydrogenation product can be optionally purified by stripping most of the HMD and 13PDA through distillation or other separation methods (such as extraction, membrane separation, etc.).

[0138] Other examples of feed streams suitable for preparing semi-purified MPMD products, such as those described herein, may include feed stream 5 ( Figure 1 Material flow 53, material flow 93, material flow 95 Figure 3 (middle) and material flow 474 or 476 ( Figure 4 ).

[0139] This embodiment serves as another implementation in which coarse MGN streams can be processed to provide semi-refined MPMD products. This implementation is suitable for some industrial applications that are less sensitive to AMC impurities, such as in epoxy curing, reactive coatings, and other applications where residual AMC is not a problem.

[0140] Example 10.

[0141] Figure 5 A schematic diagram of distillation unit 500 is shown, which can be used to separate another coproduct stream obtained from an industrial dionitrile production facility. Hexamethyleneimine (HMI) is another byproduct formed in the process of producing adiponitrile from butadiene via hydrocyanation.

[0142] A typical crude HMI stream can have a purity of approximately 80%-90% (by weight), with n-hexylamine being the main impurity (5%-15% of the total), and water, cyclohexylamine, and HMD each accounting for up to 5%. Figure 5 The coarse material stream marked 511 is fed into the first tower 501.

[0143] In one implementation, the first tower 501 may be similar to the first tower 211 in design, internal structure, and construction. Figure 2 (middle) or Tower 311 ( Figure 3 (Medium). It may include two or more packed sections, providing the equivalent of approximately 50 to 80 (e.g., approximately 60, 70, or 75) theoretical distillation separation stages. The feed may enter at the top third of column 501. The head / base conditions of column 501 may be maintained at a pressure of approximately 425 mmHg-450 mmHg / 450 mmHg-475 mmHg and a temperature of approximately 100°C-115°C / 110°C-130°C. The overhead vapor stream may be partially condensed to approximately 40°C. Column 501 concentrates most of the light organic matter, including hexylamine and water, in the overhead stream 515, while the bottom stream 513 is the concentrated HMI stream and residual impurities containing HMD.

[0144] The HMI-rich bottom feed stream 513 can be fed to the second tower 502, with feed occurring near the top-middle section of the tower. In one embodiment, the second tower 502 may be similar in design, internal structure, and construction to the second tower 221. Figure 2 (middle) or Tower 321 ( Figure 3 (Medium). It may include two or more packed sections, providing the equivalent of approximately 30 to 60 (e.g., approximately 35, 40, or 50) theoretical distillation separation stages. The head / base conditions of column 502 can be maintained at a pressure of approximately 145 mmHg–155 mmHg / 155 mmHg–165 mmHg and a temperature of approximately 80°C–90°C / 130°C–140°C. The overhead vapor stream can be partially condensed to approximately 45°C. Column 502 concentrates most of the HMI in the overhead stream 517, while the bottom stream 519 is the concentrated HMI stream along with the residual HMI (as a yield loss).

[0145] This embodiment illustrates another industrial application of the disclosed method, which can be operated to obtain a refined HMI stream (CAS Registry No. 111-49-9). The tower operations described in Examples 2 and 3 can be customized for the refining of HMIs. The HMI product can be marketed under the trade name Dytek. ® HMI amine is commercially available from INVISTA. It can be used in pharmaceuticals, textile chemicals, dyes, agricultural chemicals, corrosion inhibitors, inks, zeolite manufacturing, ore flotation, and rubber chemicals.

[0146] Example 11.

[0147] Figure 6 A schematic diagram of distillation unit 600 is shown, which can be used to separate another coproduct stream obtained from an industrial dionitrile / diamine production facility. 1,2-Diaminocyclohexane (DCH) is another byproduct formed in the process of producing diamines by hydrogenation of dionitriles.

[0148] A typical crude DCH stream can have a purity of approximately 65%-80% (by weight), containing 10%-20% HMD and less than 5% each of HMI, AMC, and MPMD, as well as other impurities including n-hexylamine and cyclohexylamine. Figure 6 The coarse material stream marked 611 is sequentially fed into the first tower marked 602.

[0149] In one embodiment, tower 602 is similar in design, internal structure, and construction to Embodiment 10 and... Figure 5 Column 502 is described in the text. Feed may enter in the lower third section of column 602. Column 602 can operate under near atmospheric pressure conditions, with the head / base at approximately 130°C-135°C / 185°C-200°C. Column 602 may be equipped with a pump-circulating condenser at the top to exchange heat and add cooled liquid back into the column to cool the overhead product to a temperature range of 70°C-80°C. Column 602 concentrates most of the light organic matter, including n-hexylamine, cyclohexylamine, and HMI, in the overhead stream 613, while the bottom stream 615 is a concentrated DCH stream and residual impurities including HMD, AMC, and MPMD.

[0150] The DCH-rich bottom feed stream 615 can be sequentially fed to a second column, designated 601, with feed occurring near the lower third section of the column. In one embodiment, column 601 is similar in design, internal structure, and construction to that of Embodiment 10 and... Figure 5Column 501 is described herein. Column 601 can operate under vacuum, wherein head / base conditions are maintained at a pressure of approximately 140 mmHg-155 mmHg / 210 mmHg-225 mmHg and a temperature of approximately 130°C-145°C / 145°C-160°C. The overhead vapor stream can be partially condensed to approximately 35°C. Column 601 concentrates most of the DCH in the overhead stream 617, while the bottom stream 619 is a concentrated HMD stream, along with some residual DCH loss and other impurities including MPMD and AMC.

[0151] This embodiment illustrates another industrial application of the disclosed method, which can be operated to obtain a purified DCH stream (CAS Registry No. 694-83-7). The tower operations described in Examples 2 and 3 can be customized for the purification of DCH. The DCH product can be marketed under the trade name Dytek. ® DCH-99 amine is commercially available from INVISTA. It can be used as a chelating agent, a chain extender in polyamides and polyurethanes, an epoxy curing agent, a catalyst in polyurethane systems, a corrosion inhibitor, and a metalworking fluid.

[0152] Example 12. (Comparative Example)

[0153] In, as in Example 1 (and Figure 1 In the method described in Example 1 for recovering purified 2-methylglutaronitrile from a crude mixture, the base temperature conditions of column 121 and partial blockage of the poorly flowing feed stream 11 can trigger undesirable side reactions and may result in trace amounts of HCN. Any HCN formed at the base of the column tends to concentrate in the overhead feed stream 9 of column 121, which is the purified product stream. The presence of HCN in the purified overhead product is undesirable for the end use. Therefore, the method of Example 1 may not provide a suitable quality of purified product.

[0154] Example 13.

[0155] Compared to Example 12, Example 2 (and) can be implemented. Figure 2 ) or Example 3 (and Figure 3 The method described in () is used to obtain a purified top product containing negligible HCN impurities or free of HCN impurities.

[0156] Material flow 97 can be obtained from the side of the tower. Figure 2 (middle) or material flow 95 ( Figure 3 (in the middle), to minimize the presence of HCN in the top product of the refining column. Furthermore, when the bottom feed stream of the column is 112 ( Figure 2 ) or 113 ( Figure 3When the flowability of the material is improved, the methods described in Examples 2 and 3 may result in less material accumulation. This can minimize side reactions and HCN formation rates at the base of the column. The purified product obtained in this example can have a very high quality compared to the purified product obtained via Examples 1 or 12.

[0157] Example 14.

[0158] In Example 2 (and Figure 2 In Example 3, material flows 72, 112, and 154 can be combined for post-processing. Similarly, in Example 3 (and Figure 3 In this process, material flows 73 and 113 can be combined for post-processing.

[0159] In one implementation scheme and according to Figure 2 The system can combine a feed stream 72 at approximately 40°C and approximately 2,000 lb / h with a feed stream 112 at approximately 188°C and approximately 900 lb / h. The resulting hot feed stream 156 can be passed through a heat exchanger to obtain a cooled combined feed stream at approximately <100°C and approximately 2,900 lb / h. This organic feed stream can be further processed and / or treated for safe disposal.

[0160] Exemplary aspects

[0161] The following exemplary aspects are provided, and their numbers should not be construed as indicating a degree of importance:

[0162] Aspect 1 provides a method for recovering and purifying 2-methylglutaronitrile from a crude mixture comprising about 70 wt% to about 90 wt% of 2-methylglutaronitrile, about 1 wt% to about 20 wt% of 2-ethylbutadionitrile, about 1 wt% to 15 wt% of adiponitrile, about 0.05 wt% to about 5 wt% of 2-cyanocyclopentylimine, and about 0.01 wt% to about 2 wt% of other impurities, the method comprising:

[0163] The crude mixture is distilled in a first distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first top stream, the first bottom stream containing ≤1 wt% of 2-ethylbutadionitrile of the total first bottom stream mass and the first top stream containing ≤1 wt% of adiponitrile of the total first top stream mass.

[0164] The first bottom stream is distilled in a second distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream, the second bottom stream containing ≥80% of the 2-cyanocyclopentylimine present in the crude mixture;

[0165] At least one of the second column overhead stream and the side draw stream is obtained from the second distillation unit;

[0166] Optionally, at least one of the second overhead stream and the side-draw stream is distilled in a third distillation unit having a head pressure in the range of 10 mmHg to 80 mmHg to produce a third overhead stream and a third bottom stream, the third overhead stream comprising ≤0.1 wt% of 2-cyanocyclopentadiene imine of the total third overhead stream mass, and the third bottom stream comprising ≤0.5 wt% of 2-ethylbutadionitrile of the total third bottom stream mass; and

[0167] The first overhead stream, the second bottom stream, and optionally the third bottom stream are combined to form a tailings mixture, the tailings mixture containing 2-cyanocyclopentadiene imine in the range of 1% to 30% by weight of the total tailings mixture mass;

[0168] in

[0169] The optional distillation is not performed on at least one of the second overhead stream and the side feed stream in the third distillation unit, and wherein the second overhead stream, the side feed stream, or a combination thereof is purified 2-methylglutaronitrile, or

[0170] In the third distillation unit, at least one of the second overhead stream and the side feed stream is selectively distilled, wherein the third overhead stream is the purified 2-methylglutaronitrile; and

[0171] The purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentylimine and ≤0.2% by weight of water.

[0172] Aspect 2 provides the method according to aspect 1, wherein the method operates continuously in the event of fewer than five flow interruptions / annual operations from the tailings mixture.

[0173] Aspect 3 provides a method according to any one of Aspects 1 to 2, wherein at least one of the second overhead stream and the side feed stream is not optionally distilled in the third distillation unit, and wherein the second overhead stream, the side feed stream, or a combination thereof is purified 2-methylglutaronitrile.

[0174] Aspect 4 provides the method according to aspect 3, wherein the second overhead feed stream is the purified 2-methylglutaronitrile.

[0175] Aspect 5 provides the method according to aspect 3, wherein the side feed stream is the purified 2-methylglutaronitrile.

[0176] Aspect 6 provides the method according to aspect 3, wherein the combination of the second overhead feed stream and the side feed stream is the purified 2-methylglutaronitrile.

[0177] Aspect 7 provides a method according to any one of Aspects 1 to 6, wherein the crude mixture further comprises ≤5% by weight of phenol and cresol, ≤10% by weight of water, ≤2% by weight of pentenoic acid, ≤0.2% by weight of borate ester or glycol, ≤100 ppm (by weight) of hydrogen cyanide and ≤100 ppm (by weight) of benzene, based on the total mass of the crude mixture.

[0178] Aspect 8 provides a method according to any one of aspects 1 to 7, wherein distilling the crude mixture in the first distillation unit includes introducing the crude mixture into the upper half of the first distillation unit.

[0179] Aspect 9 provides a method according to any one of Aspects 1 to 8, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

[0180] Aspect 10 provides a method according to any one of aspects 1 to 9, wherein distilling the first bottom feed stream in the second distillation unit includes introducing the first bottom feed stream into the lower half of the second distillation unit.

[0181] Aspect 11 provides a method according to any one of aspects 1 to 10, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0182] Aspect 12 provides a method according to any one of Aspects 1 to 11, wherein the method includes passing process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purge material.

[0183] Aspect 13 provides a method according to any one of Aspects 1 to 12, wherein the method includes passing process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purge material.

[0184] Aspect 14 provides a method according to any one of aspects 1 to 13, the method further comprising cooling the tailings mixture to a temperature of 40°C-60°C in a heat exchange device.

[0185] Aspect 15 provides a method according to any one of aspects 1 to 14, wherein the pressure of the head of the first distillation unit is in the range of 40 mmHg to 60 mmHg.

[0186] Aspect 16 provides a method according to any one of aspects 1 to 15, wherein the pressure of the pressure head of the second distillation unit is in the range of 40 mmHg to 60 mmHg.

[0187] Aspect 17 provides a method according to any one of aspects 1 to 16, wherein the top temperature and bottom temperature in the first distillation unit are maintained in the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0188] Aspect 18 provides a method according to any one of aspects 1 to 17, wherein the top temperature and bottom temperature in the second distillation unit are maintained in the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0189] Aspect 19 provides a method according to any one of aspects 1 to 18, wherein the method includes obtaining the side feed stream from near the top section of the second distillation unit.

[0190] Aspect 20 provides a method according to any one of aspects 1 to 19, wherein at least one of the second overhead stream and the side feed stream is subjected to the optional distillation in the third distillation unit, and wherein the third overhead stream is the purified 2-methylglutaronitrile.

[0191] Aspect 21 provides the method according to aspect 20, wherein the top temperature and bottom temperature in the third distillation unit are maintained in the ranges of 55°C-80°C and 160°C-190°C, respectively.

[0192] Aspect 22 provides a method according to any one of aspects 20 to 21, wherein the pressure head of the third distillation unit is in the range of 30 mmHg to 50 mmHg.

[0193] Aspect 23 provides a method according to any one of aspects 20 to 22, wherein distilling at least one of the second overhead stream and the side draw stream comprises introducing at least one of the second overhead stream and the side draw stream into the lower half of the third distillation unit.

[0194] Aspect 24 provides a method according to any one of aspects 20 to 23, wherein the third distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0195] Aspect 25 provides a method according to any one of Aspects 20 to 24, wherein the method includes passing process vapor from the top of the third distillation unit column to a third condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the third column top feed and to provide a third non-condensable vapor purging material.

[0196] Aspect 26 provides a method for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70 wt% to about 90 wt% of 2-methylglutaronitrile, about 1 wt% to about 20 wt% of 2-ethylbutadionitrile, about 1 wt% to 15 wt% of adiponitrile, about 0.05 wt% to about 5 wt% of 2-cyanocyclopentylimine, and about 0.01 wt% to about 2 wt% of other impurities, the method comprising:

[0197] The crude mixture is distilled in a first distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first top stream, the first bottom stream containing ≤1 wt% of 2-ethylbutadionitrile of the total first bottom stream mass and the first top stream containing ≤1 wt% of adiponitrile of the total first top stream mass.

[0198] The first bottom stream is distilled in a second distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream, the second bottom stream containing ≥80% of the 2-cyanocyclopentylimine present in the crude mixture;

[0199] Obtain at least one of the second column overhead stream and the side draw stream from the second distillation unit; and

[0200] The first overhead stream and the second bottom stream are combined to form a tailing mixture, the tailing mixture containing 2-cyanocyclopentadiene imine in the range of 1% to 30% by weight of the total tailing mixture mass;

[0201] The second overhead feed stream, the side feed stream, or a combination thereof is the purified 2-methylglutaronitrile, and the purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentylimine, and ≤0.2% by weight of water.

[0202] Aspect 27 provides the method according to aspect 26, wherein the method operates continuously in the event of fewer than five flow interruptions / annual operations from the tailings mixture.

[0203] Aspect 28 provides a method according to any one of aspects 26 to 27, wherein the second overhead feed stream is the purified 2-methylglutaronitrile.

[0204] Aspect 29 provides a method according to any one of aspects 26 to 27, wherein the side feed stream is the purified 2-methylglutaronitrile.

[0205] Aspect 30 provides a method according to any one of aspects 26 to 27, wherein the combination of the second overhead feed stream and the side feed stream is the purified 2-methylglutaronitrile.

[0206] Aspect 31 provides a method according to any one of aspects 26 to 30, wherein the crude mixture further comprises ≤5% by weight of phenol and cresol, ≤10% by weight of water, ≤2% by weight of pentenoic acid, ≤0.2% by weight of borate ester or glycol, ≤100 ppm (by weight) of hydrogen cyanide and ≤100 ppm (by weight) of benzene, by weight, of the total mass of the crude mixture.

[0207] Aspect 32 provides a method according to any one of aspects 26 to 31, wherein distilling the crude mixture in the first distillation unit includes introducing the crude mixture into the upper half of the first distillation unit.

[0208] Aspect 33 provides a method according to any one of aspects 26 to 32, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

[0209] Aspect 34 provides a method according to any one of aspects 26 to 33, wherein distilling the first bottom feed stream in the second distillation unit includes introducing the first bottom feed stream into the lower half of the second distillation unit.

[0210] Aspect 35 provides a method according to any one of aspects 26 to 34, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0211] Aspect 36 provides a method according to any one of aspects 26 to 35, wherein the method includes passing process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purge material.

[0212] Aspect 37 provides a method according to any one of aspects 26 to 36, wherein the method includes passing process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purging material.

[0213] Aspect 38 provides a method according to any one of aspects 26 to 37, the method further comprising cooling the tailings mixture to a temperature of 40°C-60°C in a heat exchange device.

[0214] Aspect 39 provides a method according to any one of aspects 26 to 38, wherein the pressure of the head of the first distillation unit is in the range of 40 mmHg to 60 mmHg.

[0215] Aspect 40 provides a method according to any one of aspects 26 to 39, wherein the pressure head of the second distillation unit is in the range of 40 mmHg to 60 mmHg.

[0216] Aspect 41 provides a method according to any one of aspects 26 to 40, wherein the top temperature and bottom temperature in the first distillation unit are maintained in the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0217] Aspect 42 provides a method according to any one of aspects 26 to 41, wherein the top temperature and bottom temperature in the second distillation unit are maintained in the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0218] Aspect 43 provides a method according to any one of aspects 26 to 42, wherein the method includes obtaining the side feed stream from near the top section of the second distillation unit.

[0219] Aspect 44 provides a method for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70 wt% to about 90 wt% of 2-methylglutaronitrile, about 1 wt% to about 20 wt% of 2-ethylbutadionitrile, about 1 wt% to 15 wt% of adiponitrile, about 0.05 wt% to about 5 wt% of 2-cyanocyclopentylimine, and about 0.01 wt% to about 2 wt% of other impurities, the method comprising:

[0220] The crude mixture is distilled in a first distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first top stream, the first bottom stream containing ≤1 wt% of 2-ethylbutadionitrile of the total first bottom stream mass and the first top stream containing ≤1 wt% of adiponitrile of the total first top stream mass.

[0221] The first bottom stream is distilled in a second distillation unit having a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream, the second bottom stream containing ≥80% of the 2-cyanocyclopentylimine present in the crude mixture;

[0222] At least one of the second column overhead stream and the side draw stream is obtained from the second distillation unit;

[0223] Distillation of at least one of the second overhead stream and the side feed stream in a third distillation unit having a head pressure in the range of 10 mmHg to 80 mmHg to produce a third overhead stream and a third bottom stream, the third overhead stream comprising ≤0.1 wt% of 2-cyanocyclopentadiene imine of the total third overhead stream mass, and the third bottom stream comprising ≤0.5 wt% of 2-ethylbutadionitrile of the total third bottom stream mass; and

[0224] The first overhead stream, the second bottom stream, and the third bottom stream are combined to form a tailing mixture, the tailing mixture containing 2-cyanocyclopentadiene imine in the range of 1% to 30% by weight of the total tailing mixture mass;

[0225] The third overhead feed stream is the purified 2-methylglutaronitrile, and the purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentylimine and ≤0.2% by weight of water.

[0226] Aspect 45 provides the method according to aspect 44, wherein the method operates continuously in the event of fewer than five flow interruptions / annual operations from the tailings mixture.

[0227] Aspect 46 provides a method according to any one of aspects 44 to 45, wherein the crude mixture further comprises ≤5% by weight of phenol and cresol, ≤10% by weight of water, ≤2% by weight of pentenoic acid, ≤0.2% by weight of borate ester or glycol, ≤100 ppm (by weight) of hydrogen cyanide and ≤100 ppm (by weight) of benzene, by weight.

[0228] Aspect 47 provides a method according to any one of aspects 44 to 46, wherein distilling the crude mixture in the first distillation unit includes introducing the crude mixture into the upper half of the first distillation unit.

[0229] Aspect 48 provides a method according to any one of aspects 44 to 47, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

[0230] Aspect 49 provides a method according to any one of aspects 44 to 48, wherein distilling the first bottoms stream in the second distillation unit includes introducing the first bottoms stream into the lower half of the second distillation unit.

[0231] Aspect 50 provides a method according to any one of aspects 44 to 49, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0232] Aspect 51 provides a method according to any one of aspects 44 to 50, wherein the method includes passing process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purge material.

[0233] Aspect 52 provides a method according to any one of aspects 44 to 51, wherein the method includes passing process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purging material.

[0234] Aspect 53 provides a method according to any one of aspects 44 to 52, the method further comprising cooling the tailings mixture to a temperature of 40°C-60°C in a heat exchange device.

[0235] Aspect 54 provides a method according to any one of aspects 44 to 53, wherein the pressure head of the first distillation unit is in the range of 40 mmHg to 60 mmHg.

[0236] Aspect 55 provides a method according to any one of aspects 44 to 54, wherein the pressure of the pressure head of the second distillation unit is in the range of 40 mmHg to 60 mmHg.

[0237] Aspect 56 provides a method according to any one of aspects 44 to 55, wherein the top temperature and bottom temperature in the first distillation unit are maintained in the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0238] Aspect 57 provides a method according to any one of aspects 44 to 56, wherein the top temperature and bottom temperature in the second distillation unit are maintained in the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0239] Aspect 58 provides a method according to any one of aspects 44 to 57, wherein the method includes obtaining the side feed stream from near the top section of the second distillation unit.

[0240] Aspect 59 provides a method according to any one of aspects 44 to 58, wherein the top temperature and bottom temperature in the third distillation unit are maintained in the ranges of 55°C-80°C and 160°C-190°C, respectively.

[0241] Aspect 60 provides a method according to any one of aspects 44 to 59, wherein the pressure head of the third distillation unit is in the range of 30 mmHg to 50 mmHg.

[0242] Aspect 61 provides a method according to any one of aspects 44 to 60, wherein distilling at least one of the second overhead stream and the side draw stream comprises introducing at least one of the second overhead stream and the side draw stream into the lower half of the third distillation unit.

[0243] Aspect 62 provides a method according to any one of aspects 44 to 61, wherein the third distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0244] Aspect 63 provides a method according to any one of aspects 44 to 62, wherein the method includes passing process vapor from the top of the third distillation unit column to a third condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the third column top feed and to provide a third non-condensable vapor purging material.

[0245] Aspect 64 provides a method for recovering purified hexamethyleneimine (HMI) from a crude mixture comprising about 80 wt% to about 90 wt% of HMI, about 5 wt% to about 15 wt% of n-hexylamine, about 0 wt% to 5 wt% of water, about 0 wt% to 5 wt% of cyclohexylamine, and about 0 wt% to about 5 wt% of hexamethylenediamine (HMD), the method comprising:

[0246] The crude mixture is distilled in a first distillation unit having a head pressure in the range of 400 mmHg to 500 mmHg to produce a first bottom stream and a first top stream, the first bottom stream containing concentrated HMI containing HMD, and the first top stream containing n-hexylamine and optionally containing water.

[0247] The first bottom stream is distilled in a second distillation unit with a head pressure in the range of 100 mmHg to 200 mmHg to produce a second bottom stream, the second bottom stream containing concentrated HMD containing HMI; and

[0248] At least one of the second column overhead stream and the side draw stream is obtained from the second distillation unit;

[0249] The second overhead feed stream, the side feed stream, or a combination thereof is the purified HMI, and the purified HMI is at least 99% by weight HMI.

[0250] Aspect 65 provides the method according to aspect 64, wherein the second overhead feed stream is the purified HMI.

[0251] Aspect 66 provides the method according to aspect 64, wherein the side feed stream is the purified HMI.

[0252] Aspect 67 provides the method according to aspect 64, wherein the combination of the second overhead feed stream and the side feed stream is the purified HMI.

[0253] Aspect 68 provides a method according to any one of aspects 64 to 67, wherein distilling the crude mixture in the first distillation unit includes introducing the crude mixture into the upper half of the first distillation unit.

[0254] Aspect 69 provides a method according to any one of aspects 64 to 68, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

[0255] Aspect 70 provides a method according to any one of aspects 64 to 69, wherein distilling the first bottom feed stream in the second distillation unit includes introducing the first bottom feed stream into the upper half of the second distillation unit.

[0256] Aspect 71 provides a method according to any one of aspects 64 to 70, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0257] Aspect 72 provides a method according to any one of aspects 64 to 71, wherein the method includes passing process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purge material.

[0258] Aspect 73 provides a method according to any one of aspects 64 to 72, wherein the method includes passing process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purging material.

[0259] Aspect 74 provides a method according to any one of aspects 64 to 73, wherein the pressure head of the first distillation unit is in the range of 425 mmHg to 450 mmHg.

[0260] Aspect 75 provides a method according to any one of aspects 64 to 74, wherein the pressure of the pressure head of the second distillation unit is in the range of 145 mmHg to 155 mmHg.

[0261] Aspect 76 provides a method according to any one of aspects 64 to 75, wherein the top temperature and bottom temperature in the first distillation unit are maintained in the ranges of 110°C-115°C and 110°C-130°C, respectively.

[0262] Aspect 77 provides a method according to any one of aspects 64 to 76, wherein the top temperature and bottom temperature in the second distillation unit are maintained in the ranges of 80°C-90°C and 130°C-140°C, respectively.

[0263] Aspect 78 provides a method according to any one of aspects 64 to 77, wherein the method includes obtaining the side feed stream from near the top section of the second distillation unit.

[0264] Aspect 79 provides a method according to any one of aspects 64 to 78, wherein the purified HMI is 99% to 99.9% by weight of HMI.

[0265] Aspect 80 provides a method according to any one of aspects 64 to 79, wherein the purified HMI contains less than or equal to 0.40 wt% cyclohexylamine, less than or equal to 0.02 wt% n-hexylamine, less than or equal to 0.07 wt% water and less than or equal to 0.02 wt% HMD.

[0266] Aspect 81 provides a method for recovering purified 1,2-diaminocyclohexane (DCH) from a crude mixture comprising about 65 wt% to about 80 wt% of DCH, about 10 wt% to about 20 wt% of hexamethylenediamine (HMD), about 0 wt% to 5 wt% of hexamethyleneimine (HMI), about 0 wt% to about 5 wt% of 2-(aminomethyl)-cyclopentanamine (AMC), about 0 wt% to about 5 wt% of 2-methyl-pentamethylenediamine (MPMD), and about 0 wt% to about 2 wt% of other impurities comprising n-hexylamine, cyclohexylamine, or combinations thereof, the method comprising:

[0267] The crude mixture is distilled in a first distillation unit having a head pressure in the range of 700 mmHg to 850 mmHg to produce a first bottom stream and a first top stream, the first bottom stream containing concentrated DCH optionally containing HMD, AMC, MPMD or a combination thereof, and the first top stream containing HMD and optionally containing AMC, MPMD or a combination thereof.

[0268] The first bottom stream is distilled in a second distillation unit having a head pressure in the range of 100 mmHg to 200 mmHg to produce a second bottom stream, the second bottom stream containing concentrated HMD containing DCH and optionally containing AMC, MPMD or a combination thereof.

[0269] At least one of the second column overhead stream and the side draw stream is obtained from the second distillation unit;

[0270] The second overhead feed stream, the side feed stream, or a combination thereof is the purified DCH, and the purified DCH is at least 98.5% by weight DCH.

[0271] Aspect 82 provides the method according to aspect 81, wherein the second overhead feed stream is the purified DCH.

[0272] Aspect 83 provides the method according to aspect 81, wherein the side feed stream is the purified DCH.

[0273] Aspect 84 provides the method according to aspect 81, wherein the combination of the second overhead feed stream and the side feed stream is the purified DCH.

[0274] Aspect 85 provides a method according to any one of aspects 81 to 84, wherein distilling the crude mixture in the first distillation unit includes introducing the crude mixture into the lower half of the first distillation unit.

[0275] Aspect 86 provides a method according to any one of aspects 81 to 85, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0276] Aspect 87 provides a method according to any one of aspects 81 to 86, wherein distilling the first bottoms stream in the second distillation unit includes introducing the first bottoms stream into the lower half of the second distillation unit.

[0277] Aspect 88 provides a method according to any one of aspects 81 to 87, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

[0278] Aspect 89 provides a method according to any one of aspects 81 to 88, wherein the method includes passing process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purging material.

[0279] Aspect 90 provides a method according to any one of aspects 81 to 89, wherein the method includes passing process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condensing the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purge material.

[0280] Aspect 91 provides a method according to any one of aspects 81 to 90, wherein the pressure head of the first distillation unit is about 760 mmHg.

[0281] Aspect 92 provides a method according to any one of aspects 81 to 91, wherein the pressure of the pressure head of the second distillation unit is in the range of 145 mmHg to 155 mmHg.

[0282] Aspect 93 provides a method according to any one of aspects 81 to 92, wherein the top temperature and bottom temperature in the first distillation unit are maintained in the ranges of 130°C-135°C and 185°C-200°C, respectively.

[0283] Aspect 94 provides a method according to any one of aspects 81 to 93, wherein the top temperature and bottom temperature in the second distillation unit are maintained in the ranges of 130°C-145°C and 145°C-160°C, respectively.

[0284] Aspect 95 provides a method according to any one of aspects 81 to 94, wherein the method includes obtaining the side feed stream from near the top section of the second distillation unit.

[0285] Aspect 96 provides a method according to any one of aspects 81 to 95, wherein the purified DCH is 98.5% to 99.9% by weight of DCH.

[0286] Aspect 97 provides a method according to any one of aspects 81 to 96, wherein the purified DCH contains less than or equal to 0.1% by weight of 2-methylpentamethylenediamine, less than or equal to 0.1% by weight of hexamethylenediamine and less than or equal to 0.1% by weight of water.

[0287] Aspect 98 provides an apparatus for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70 wt% to about 90 wt% of 2-methylglutaronitrile, about 1 wt% to about 20 wt% of 2-ethylbutadionitrile, about 1 wt% to 15 wt% of adiponitrile, about 0.05 wt% to about 5 wt% of 2-cyanocyclopentylimine, and about 0.01 wt% to about 2 wt% of other impurities, the apparatus comprising:

[0288] A first distillation unit is configured to distill the crude mixture at a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first top stream, the first bottom stream containing ≤1 wt% 2-ethylbutadionitrile of the total first bottom stream mass, and the first top stream containing ≤1 wt% adiponitrile of the total first top stream mass.

[0289] A second distillation unit is configured to distill the first bottom stream at a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream, the second bottom stream containing ≥80% of 2-cyanocyclopentylimine present in the crude mixture, wherein the second distillation unit is configured to provide at least one of a second overhead stream and a side feed stream.

[0290] An optional third distillation unit is configured to distill at least one of the second overhead stream and the side-draw stream at a head pressure ranging from 10 mmHg to 80 mmHg to produce a third overhead stream and a third bottom stream, the third overhead stream comprising ≤0.1 wt% of 2-cyanocyclopentadiene imine by mass of the total third overhead stream, and the third bottom stream comprising ≤0.5 wt% of 2-ethylbutadionitrile by mass of the total third bottom stream; and

[0291] One or more flow channels are configured to combine a first overhead stream, a second bottom stream, and optionally a third bottom stream to form a tailings mixture, the tailings mixture comprising 2-cyanocyclopentadiene imine in the range of 1% to 30% by weight of the total tailings mixture mass.

[0292] in

[0293] The optional third distillation unit is not present, and the second overhead feed stream, the side feed stream, or a combination thereof is the purified 2-methylglutaronitrile, or

[0294] The optional third distillation unit is present, and the overhead feed stream of the third column is the purified 2-methylglutaronitrile; and

[0295] The purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentylimine and ≤0.2% by weight of water.

[0296] Aspect 99 provides an apparatus according to aspect 98, wherein the apparatus is capable of continuous operation with fewer than five interruptions in the flow of the tailings mixture per year.

[0297] Aspect 100 provides an apparatus according to any one of aspects 98 to 99, wherein the optional third distillation unit is absent, and wherein the second overhead feed stream, the side feed stream, or a combination thereof is the purified 2-methylglutaronitrile.

[0298] Aspect 101 provides an apparatus according to aspect 100, wherein the second overhead feed stream is the purified 2-methylglutaronitrile.

[0299] Aspect 102 provides an apparatus according to aspect 100, wherein the side feed stream is the purified 2-methylglutaronitrile.

[0300] Aspect 103 provides an apparatus according to aspect 100, wherein the combination of the second overhead feed stream and the side feed stream is the purified 2-methylglutaronitrile.

[0301] Aspect 104 provides an apparatus according to any one of aspects 98 to 103, wherein the crude mixture further comprises ≤5% by weight of phenol and cresol, ≤10% by weight of water, ≤2% by weight of pentenoic acid, ≤0.2% by weight of borate ester or glycol, ≤100 ppm (by weight) of hydrogen cyanide and ≤100 ppm (by weight) of benzene, by weight.

[0302] Aspect 105 provides an apparatus according to any one of aspects 98 to 104, wherein the first distillation unit is configured to introduce the crude mixture into the upper half of the first distillation unit.

[0303] Aspect 106 provides an apparatus according to any one of aspects 98 to 105, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

[0304] Aspect 107 provides an apparatus according to any one of aspects 98 to 106, wherein the second distillation unit is configured to introduce the first column bottoms stream into the lower half of the second distillation unit.

[0305] Aspect 108 provides an apparatus according to any one of aspects 98 to 107, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0306] Aspect 109 provides an apparatus according to any one of aspects 98 to 108, wherein the first distillation unit is configured to pass process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purging material.

[0307] Aspect 110 provides an apparatus according to any one of aspects 98 to 109, wherein the second distillation unit is configured to pass process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purge material.

[0308] Aspect 111 provides an apparatus according to any one of aspects 98 to 110, the apparatus further comprising a heat exchange device configured to cool the tailings mixture to a temperature of 40°C to 60°C.

[0309] Aspect 112 provides an apparatus according to any one of aspects 98 to 111, wherein the first distillation unit is configured to distill the crude mixture at a pressure head in the range of 40 mmHg to 60 mmHg.

[0310] Aspect 113 provides an apparatus according to any one of aspects 98 to 112, wherein the second distillation unit is configured to distill the first column bottom stream at a head pressure in the range of 40 mmHg to 60 mmHg.

[0311] Aspect 114 provides an apparatus according to any one of aspects 98 to 113, wherein the first distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0312] Aspect 115 provides an apparatus according to any one of aspects 98 to 114, wherein the second distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0313] Aspect 116 provides an apparatus according to any one of aspects 98 to 115, wherein the second distillation unit is configured to provide the side feed stream from near the top section of the second distillation unit.

[0314] Aspect 117 provides an apparatus according to any one of aspects 98 to 116, wherein the third distillation unit is present, and wherein the third overhead feed stream is the purified 2-methylglutaronitrile.

[0315] Aspect 118 provides an apparatus according to aspect 117, wherein the third distillation unit is configured to maintain the top and bottom temperatures therein within the ranges of 55°C-80°C and 160°C-190°C, respectively.

[0316] Aspect 119 provides an apparatus according to any one of aspects 117 to 118, wherein the third distillation unit is configured to distill at least one of the second overhead stream and the side feed stream at a head pressure in the range of 30 mmHg to 50 mmHg.

[0317] Aspect 120 provides an apparatus according to any one of aspects 117 to 119, wherein the third distillation unit is configured to introduce at least one of the second overhead feed stream and the side feed stream into the lower half of the third distillation unit.

[0318] Aspect 121 provides an apparatus according to any one of aspects 117 to 120, wherein the third distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0319] Aspect 122 provides an apparatus according to any one of aspects 117 to 121, wherein the third distillation unit is configured to pass process vapor from the top of the third distillation unit column to a third condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the third column top feed and to provide a third non-condensable vapor purging material.

[0320] Aspect 123 provides an apparatus for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70 wt% to about 90 wt% of 2-methylglutaronitrile, about 1 wt% to about 20 wt% of 2-ethylbutadionitrile, about 1 wt% to 15 wt% of adiponitrile, about 0.05 wt% to about 5 wt% of 2-cyanocyclopentylimine, and about 0.01 wt% to about 2 wt% of other impurities, the apparatus comprising:

[0321] A first distillation unit is configured to distill the crude mixture at a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first top stream, the first bottom stream containing ≤1 wt% 2-ethylbutadionitrile of the total first bottom stream mass, and the first top stream containing ≤1 wt% adiponitrile of the total first top stream mass.

[0322] A second distillation unit, configured to distill the first bottom stream at a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream, the second bottom stream containing ≥80% of the 2-cyanocyclopentylimine present in the crude mixture, wherein the second distillation unit is configured to provide at least one of a second overhead stream and a side-draw stream; and

[0323] One or more flow channels are configured to combine the first overhead stream and the second bottom stream to form a tailing mixture, the tailing mixture comprising 2-cyanocyclopentadiene imine in the range of 1% to 30% by weight of the total tailing mixture mass;

[0324] The second overhead feed stream, the side feed stream, or a combination thereof is the purified 2-methylglutaronitrile, and the purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentylimine, and ≤0.2% by weight of water.

[0325] Aspect 124 provides the apparatus according to aspect 123, wherein the apparatus is capable of continuous operation, wherein the flow interruption from the tailings mixture occurs less than five times per year.

[0326] Aspect 125 provides an apparatus according to any one of aspects 123 to 124, wherein the second overhead feed stream is the purified 2-methylglutaronitrile.

[0327] Aspect 126 provides an apparatus according to any one of aspects 123 to 125, wherein the side feed stream is the purified 2-methylglutaronitrile.

[0328] Aspect 127 provides an apparatus according to any one of aspects 123 to 126, wherein the combination of the second overhead feed stream and the side feed stream is the purified 2-methylglutaronitrile.

[0329] Aspect 128 provides an apparatus according to any one of aspects 123 to 127, wherein the crude mixture further comprises ≤5% by weight of phenol and cresol, ≤10% by weight of water, ≤2% by weight of pentenoic acid, ≤0.2% by weight of borate ester or glycol, ≤100 ppm (by weight) of hydrogen cyanide and ≤100 ppm (by weight) of benzene, by weight.

[0330] Aspect 129 provides an apparatus according to any one of aspects 123 to 128, wherein the first distillation unit is configured to introduce the crude mixture into the upper half of the first distillation unit.

[0331] Aspect 130 provides an apparatus according to any one of aspects 123 to 129, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

[0332] Aspect 131 provides an apparatus according to any one of aspects 123 to 130, wherein the second distillation unit is configured to introduce the first column bottoms stream into the lower half of the second distillation unit.

[0333] Aspect 132 provides an apparatus according to any one of aspects 123 to 131, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0334] Aspect 133 provides an apparatus according to any one of aspects 123 to 132, wherein the first distillation unit is configured to pass process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purge material.

[0335] Aspect 134 provides an apparatus according to any one of aspects 123 to 133, wherein the second distillation unit is configured to pass process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purge material.

[0336] Aspect 135 provides an apparatus according to any one of aspects 123 to 134, the apparatus further comprising a heat exchange device configured to cool the tailings mixture to a temperature of 40°C to 60°C.

[0337] Aspect 136 provides an apparatus according to any one of aspects 123 to 135, wherein the first distillation unit is configured to distill the crude mixture at a pressure head in the range of 40 mmHg to 60 mmHg.

[0338] Aspect 137 provides an apparatus according to any one of aspects 123 to 136, wherein the second distillation unit is configured to distill the first column bottom stream at a head pressure in the range of 40 mmHg to 60 mmHg.

[0339] Aspect 138 provides an apparatus according to any one of aspects 123 to 137, wherein the first distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0340] Aspect 139 provides an apparatus according to any one of aspects 123 to 138, wherein the second distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0341] Aspect 140 provides an apparatus according to any one of aspects 123 to 139, wherein the second distillation unit is configured to provide the side feed stream from near the top section of the second distillation unit.

[0342] Aspect 141 provides an apparatus for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70 wt% to about 90 wt% of 2-methylglutaronitrile, about 1 wt% to about 20 wt% of 2-ethylbutadionitrile, about 1 wt% to 15 wt% of adiponitrile, about 0.05 wt% to about 5 wt% of 2-cyanocyclopentylimine, and about 0.01 wt% to about 2 wt% of other impurities, the apparatus comprising:

[0343] A first distillation unit is configured to distill the crude mixture at a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first top stream, the first bottom stream containing ≤1 wt% 2-ethylbutadionitrile of the total first bottom stream mass, and the first top stream containing ≤1 wt% adiponitrile of the total first top stream mass.

[0344] A second distillation unit is configured to distill the first bottom stream at a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream, the second bottom stream containing ≥80% of 2-cyanocyclopentylimine present in the crude mixture, wherein the second distillation unit is configured to provide at least one of a second overhead stream and a side feed stream.

[0345] A third distillation unit, configured to distill at least one of the second overhead stream and the side-draw stream at a head pressure ranging from 10 mmHg to 80 mmHg to produce a third overhead stream and a third bottom stream, wherein the third overhead stream contains ≤0.1 wt% of 2-cyanocyclopentadiene imine by mass of the total third overhead stream, and the third bottom stream contains ≤0.5 wt% of 2-ethylbutadionitrile by mass of the total third bottom stream; and

[0346] One or more flow channels are configured to combine the first overhead stream, the second bottom stream and the third bottom stream to form a tailing mixture, the tailing mixture comprising 2-cyanocyclopentadiene imine in the range of 1% to 30% by weight of the total tailing mixture mass;

[0347] The third overhead feed stream is the purified 2-methylglutaronitrile, and the purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentylimine and ≤0.2% by weight of water.

[0348] Aspect 142 provides an apparatus according to aspect 141, wherein the apparatus is capable of continuous operation, wherein the flow interruption from the tailings mixture occurs less than five times per year.

[0349] Aspect 143 provides an apparatus according to any one of aspects 141 to 142, wherein the crude mixture further comprises ≤5% by weight of phenol and cresol, ≤10% by weight of water, ≤2% by weight of pentenoic acid, ≤0.2% by weight of borate ester or glycol, ≤100 ppm (by weight) of hydrogen cyanide and ≤100 ppm (by weight) of benzene, by weight.

[0350] Aspect 144 provides an apparatus according to any one of aspects 141 to 143, wherein the first distillation unit is configured to introduce the crude mixture into the upper half of the first distillation unit.

[0351] Aspect 145 provides an apparatus according to any one of aspects 141 to 144, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

[0352] Aspect 146 provides an apparatus according to any one of aspects 141 to 145, wherein the second distillation unit is configured to introduce the first column bottoms stream into the lower half of the second distillation unit.

[0353] Aspect 147 provides an apparatus according to any one of aspects 141 to 146, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0354] Aspect 148 provides an apparatus according to any one of aspects 141 to 147, wherein the first distillation unit is configured to pass process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purge material.

[0355] Aspect 149 provides an apparatus according to any one of aspects 141 to 148, wherein the second distillation unit is configured to pass top process vapor from the second distillation unit to a second condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purge material.

[0356] Aspect 150 provides an apparatus according to any one of aspects 141 to 149, the apparatus further comprising a heat exchange device configured to cool the tailings mixture to a temperature of 40°C to 60°C.

[0357] Aspect 151 provides an apparatus according to any one of aspects 141 to 150, wherein the first distillation unit is configured to distill the crude mixture at a pressure head in the range of 40 mmHg to 60 mmHg.

[0358] Aspect 152 provides an apparatus according to any one of aspects 141 to 151, wherein the second distillation unit is configured to distill the first column bottom stream at a head pressure in the range of 40 mmHg to 60 mmHg.

[0359] Aspect 153 provides an apparatus according to any one of aspects 141 to 152, wherein the first distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0360] Aspect 154 provides an apparatus according to any one of aspects 141 to 153, wherein the second distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 45°C-60°C and 190°C-205°C, respectively.

[0361] Aspect 155 provides an apparatus according to any one of aspects 141 to 154, wherein the second distillation unit is configured to provide the side feed stream from near the top section of the second distillation unit.

[0362] Aspect 156 provides an apparatus according to any one of aspects 151 to 155, wherein the third distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 55°C-80°C and 160°C-190°C, respectively.

[0363] Aspect 157 provides an apparatus according to any one of aspects 151 to 156, wherein the third distillation unit is configured to distill at least one of the second overhead stream and the side feed stream at a head pressure in the range of 30 mmHg to 50 mmHg.

[0364] Aspect 158 ​​provides an apparatus according to any one of aspects 151 to 157, wherein the third distillation unit is configured to introduce at least one of the second overhead feed stream and the side feed stream into the lower half of the third distillation unit.

[0365] Aspect 159 provides an apparatus according to any one of aspects 151 to 158, wherein the third distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0366] Aspect 160 provides an apparatus according to any one of aspects 151 to 159, wherein the third distillation unit is configured to pass process vapor from the top of the third distillation unit column to a third condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the third column top feed and to provide a third non-condensable vapor purging material.

[0367] Aspect 161 provides an apparatus for recovering purified hexamethyleneimine (HMI) from a crude mixture comprising about 80 wt% to about 90 wt% of HMI, about 5 wt% to about 15 wt% of n-hexylamine, about 0 wt% to 5 wt% of water, about 0 wt% to 5 wt% of cyclohexylamine, and about 0 wt% to about 5 wt% of hexamethylenediamine (HMD), the apparatus comprising:

[0368] A first distillation unit, configured to distill the crude mixture at a head pressure in the range of 400 mmHg to 500 mmHg to produce a first bottom stream and a first overhead stream, the first bottom stream containing concentrated HMI containing HMD, and the first overhead stream containing n-hexylamine and optionally water; and

[0369] A second distillation unit is configured to distill the first bottom stream at a head pressure in the range of 100 mmHg to 200 mmHg to produce a second bottom stream, the second bottom stream containing concentrated HMD containing HMI, wherein the second distillation unit is configured to provide at least one of a second overhead stream and a side feed stream.

[0370] The second overhead feed stream, the side feed stream, or a combination thereof is the purified HMI, and the purified HMI is at least 99% by weight HMI.

[0371] Aspect 162 provides an apparatus according to aspect 161, wherein the second overhead feed stream is the purified HMI.

[0372] Aspect 163 provides an apparatus according to aspect 161, wherein the side feed stream is the purified HMI.

[0373] Aspect 164 provides an apparatus according to aspect 161, wherein the combination of the second overhead feed stream and the side feed stream is the purified HMI.

[0374] Aspect 165 provides an apparatus according to any one of aspects 161 to 164, wherein the first distillation unit is configured to introduce the crude mixture into the upper half of the first distillation unit.

[0375] Aspect 166 provides an apparatus according to any one of aspects 161 to 165, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

[0376] Aspect 167 provides an apparatus according to any one of aspects 161 to 166, wherein the second distillation unit is configured to introduce the first bottom feed stream into the upper half of the second distillation unit.

[0377] Aspect 168 provides an apparatus according to any one of aspects 161 to 167, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0378] Aspect 169 provides an apparatus according to any one of aspects 161 to 168, wherein the first distillation unit is configured to pass process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purge material.

[0379] Aspect 170 provides an apparatus according to any one of aspects 161 to 169, wherein the second distillation unit is configured to pass process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purge material.

[0380] Aspect 171 provides an apparatus according to any one of aspects 161 to 170, wherein the first distillation unit is configured to distill the crude mixture at a pressure head in the range of 425 mmHg to 450 mmHg.

[0381] Aspect 172 provides an apparatus according to any one of aspects 161 to 171, wherein the second distillation unit is configured to distill the first column bottom stream at a head pressure in the range of 145 mmHg to 155 mmHg.

[0382] Aspect 173 provides an apparatus according to any one of aspects 161 to 172, wherein the first distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 110°C-115°C and 110°C-130°C, respectively.

[0383] Aspect 174 provides an apparatus according to any one of aspects 161 to 173, wherein the second distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 80°C-90°C and 130°C-140°C, respectively.

[0384] Aspect 175 provides an apparatus according to any one of aspects 161 to 174, wherein the second distillation unit is configured to provide the side feed stream from near the top section of the second distillation unit.

[0385] Aspect 176 provides an apparatus according to any one of aspects 161 to 175, wherein the purified HMI is 99% to 99.9% by weight of HMI.

[0386] Aspect 177 provides an apparatus according to any one of aspects 161 to 176, wherein the purified HMI contains less than or equal to 0.40% by weight of cyclohexylamine, less than or equal to 0.02% by weight of n-hexylamine, less than or equal to 0.07% by weight of water and less than or equal to 0.02% by weight of HMD.

[0387] Aspect 178 provides an apparatus for recovering purified 1,2-diaminocyclohexane (DCH) from a crude mixture comprising about 65 wt% to about 80 wt% DCH, about 10 wt% to about 20 wt% hexamethylenediamine (HMD), about 0 wt% to 5 wt% hexamethyleneimine (HMI), about 0 wt% to about 5 wt% 2-(aminomethyl)-cyclopentanamine (AMC), about 0 wt% to about 5 wt% 2-methyl-pentamethylenediamine (MPMD), and about 0 wt% to about 2 wt% other impurities comprising n-hexylamine, cyclohexylamine, or combinations thereof, the apparatus comprising:

[0388] A first distillation unit is configured to distill the crude mixture at a head pressure in the range of 700 mmHg to 850 mmHg to produce a first bottom stream and a first top stream. The first bottom stream contains concentrated DCH, optionally containing HMD, AMC, MPMD, or a combination thereof. The first top stream contains HMD and optionally contains AMC, MPMD, or a combination thereof.

[0389] A second distillation unit is configured to distill the first bottom stream at a head pressure in the range of 100 mmHg to 200 mmHg to produce a second bottom stream, the second bottom stream comprising concentrated HMD containing DCH and optionally containing AMC, MPMD or a combination thereof, wherein the second distillation unit is configured to provide at least one of a second overhead stream and a side feed stream.

[0390] The second overhead feed stream, the side feed stream, or a combination thereof is the purified DCH, and the purified DCH is at least 98.5% by weight DCH.

[0391] Aspect 179 provides an apparatus according to aspect 178, wherein the second overhead feed stream is the purified DCH.

[0392] Aspect 180 provides an apparatus according to aspect 178, wherein the side feed stream is the purified DCH.

[0393] Aspect 181 provides an apparatus according to aspect 178, wherein the combination of the second overhead feed stream and the side feed stream is the purified DCH.

[0394] Aspect 182 provides an apparatus according to any one of aspects 178 to 181, wherein the first distillation unit is configured to introduce the crude mixture into the lower half of the first distillation unit.

[0395] Aspect 183 provides an apparatus according to any one of aspects 178 to 182, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

[0396] Aspect 184 provides an apparatus according to any one of aspects 178 to 183, wherein the second distillation unit is configured to introduce the first column bottoms stream into the lower half of the second distillation unit.

[0397] Aspect 185 provides an apparatus according to any one of aspects 178 to 184, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

[0398] Aspect 186 provides an apparatus according to any one of aspects 178 to 185, wherein the first distillation unit is configured to pass process vapor from the top of the first distillation unit to a first condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purge material.

[0399] Aspect 187 provides an apparatus according to any one of aspects 178 to 186, wherein the second distillation unit is configured to pass process vapor from the top of the second distillation unit to a second condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purge material.

[0400] Aspect 188 provides an apparatus according to any one of aspects 178 to 187, wherein the first distillation unit is configured to distill the crude mixture at a pressure head of about 760 mmHg.

[0401] Aspect 189 provides an apparatus according to any one of aspects 178 to 188, wherein the second distillation unit is configured to distill the first column bottom stream at a head pressure in the range of 145 mmHg to 155 mmHg.

[0402] Aspect 190 provides an apparatus according to any one of aspects 178 to 189, wherein the first distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 130°C-135°C and 185°C-200°C, respectively.

[0403] Aspect 191 provides an apparatus according to any one of aspects 178 to 190, wherein the second distillation unit is configured to maintain the top temperature and bottom temperature therein within the ranges of 130°C-145°C and 145°C-160°C, respectively.

[0404] Aspect 192 provides an apparatus according to any one of aspects 178 to 191, wherein the second distillation unit is configured to provide the side feed stream from near the top section of the second distillation unit.

[0405] Aspect 193 provides an apparatus according to any one of aspects 178 to 192, wherein the purified DCH is 98.5% to 99.9% by weight of DCH.

[0406] Aspect 194 provides an apparatus according to any one of aspects 178 to 193, wherein the purified DCH contains less than or equal to 0.1% by weight of 2-methylpentamethylenediamine, less than or equal to 0.1% by weight of hexamethylenediamine and less than or equal to 0.1% by weight of water.

[0407] Aspect 195 provides a method for recovering purified material from a crude mixture, the method comprising:

[0408] The crude mixture is distilled in a first distillation unit with pressure head to produce a first bottom stream and a first top stream.

[0409] The first column bottom stream is distilled in a second distillation unit with head pressure to produce a second column bottom stream; and

[0410] At least one of the second column overhead stream and the side draw stream is obtained from the second distillation unit;

[0411] The second overhead feed stream, the side feed stream, or a combination thereof are the purified material;

[0412] in

[0413] The method is a method for recovering purified hexamethyleneimine (HMI) from the crude mixture, the crude mixture comprising about 80% to about 90% by weight of HMI, about 5% to about 15% by weight of n-hexylamine, about 0% to 5% by weight of water, about 0% to 5% by weight of cyclohexylamine, and about 0% to about 5% by weight of hexamethylenediamine (HMD), wherein the first distillation unit head pressure is in the range of 400 mmHg to 500 mmHg, the first bottom stream contains concentrated HMI containing HMD, the first overhead stream contains n-hexylamine and optionally contains water, the second distillation head unit head pressure is in the range of 100 mmHg to 200 mmHg, the second bottom stream contains concentrated HMD containing HMI, the second overhead stream, the side feed stream, or a combination thereof is the purified material and is purified HMI, and the purified HMI is at least 99% by weight HMI, or

[0414] The method is a method for recovering purified 1,2-diaminocyclohexane (DCH) from the crude mixture, which contains about 65% to about 80% by weight of DCH, about 10% to about 20% by weight of hexamethylenediamine (HMD), about 0% to 5% by weight of hexamethyleneimine (HMI), about 0% to about 5% by weight of 2-(aminomethyl)-cyclopentanamine (AMC), about 0% to about 5% by weight of 2-methyl-pentamethylenediamine (MPMD), and about 0% to about 2% by weight of other impurities comprising n-hexylamine, cyclohexylamine, or combinations thereof, wherein the head pressure of the first distillation unit is between 700 mmHg and... Within the range of 800 mmHg, the first bottom feed stream contains concentrated DCH optionally containing HMD, AMC, MPMD, or a combination thereof; the first overhead feed stream contains HMD optionally containing AMC, MPMD, or a combination thereof; the second distillation unit head pressure is in the range of 100 mmHg to 200 mmHg; the second bottom feed stream contains concentrated HMD containing DCH and optionally containing AMC, MPMD, or a combination thereof; the second overhead feed stream, the side feed stream, or a combination thereof is the purified material and is purified DCH; and the purified DCH is at least 98.5% by weight DCH.

[0415] Aspect 196 provides an apparatus for recovering purified material from a crude mixture, the apparatus comprising:

[0416] A first distillation unit, configured to distill the crude mixture under head pressure to produce a first bottom stream and a first top stream; and

[0417] A second distillation unit is configured to distill the first bottom stream under a pressure head to produce a second bottom stream, wherein the second distillation unit is configured to provide at least one of a second top stream and a side-draw stream.

[0418] in

[0419] The apparatus is used to recover purified hexamethyleneimine (HMI) from a crude mixture comprising about 80% to about 90% by weight of HMI, about 5% to about 15% by weight of n-hexylamine, about 0% to 5% by weight of water, about 0% to 5% by weight of cyclohexylamine, and about 0% to about 5% by weight of hexamethylenediamine (HMD). The head pressure of the first distillation unit is maintained in the range of 400 mmHg to 500 mmHg. The first bottom stream contains concentrated HMI containing HMD, and the first overhead stream contains n-hexylamine and optionally water. The head pressure of the second distillation unit is maintained in the range of 100 mmHg to 200 mmHg. The second bottom stream contains concentrated HMD containing HMI. The second overhead stream, the side feed stream, or a combination thereof is the purified material and is purified HMI, and the purified HMI is at least 99% by weight HMI, or...

[0420] The apparatus is used to recover purified 1,2-diaminocyclohexane (DCH) from a crude mixture comprising about 65% to about 80% by weight of DCH, about 10% to about 20% by weight of hexamethylenediamine (HMD), about 0% to 5% by weight of hexamethyleneimine (HMI), about 0% to about 5% by weight of 2-(aminomethyl)-cyclopentanamine (AMC), about 0% to about 5% by weight of 2-methyl-pentamethylenediamine (MPMD), and about 0% to about 2% by weight of other impurities comprising n-hexylamine, cyclohexylamine, or combinations thereof, wherein the head pressure of the first distillation unit is maintained at 700 mmHg. Within the range of 850 mmHg, the first bottom stream contains concentrated DCH, optionally containing HMD, AMC, MPMD, or a combination thereof; the first overhead stream contains HMD and optionally contains AMC and MPMD; the second distillation unit head pressure is maintained within the range of 100 mmHg to 200 mmHg; the second bottom stream contains concentrated HMD containing DCH and optionally containing AMC, MPMD, or a combination thereof; the second overhead stream, the side feed stream, or a combination thereof is the purified material and is purified DCH; and the purified DCH is at least 98.5% by weight DCH.

[0421] Aspect 197 provides a method or apparatus according to any one or any combination of aspects 1 to 196, wherein the method or apparatus is optionally configured such that all of the elements or options can be used or selected from them.

Claims

1. An apparatus for recovering purified 2-methylglutaronitrile from a crude mixture comprising about 70% to about 90% by weight of 2-methylglutaronitrile, about 1% to about 20% by weight of 2-ethylbutadionitrile, about 1% to 15% by weight of adiponitrile, about 0.05% to about 5% by weight of 2-cyanocyclopentylimine, and about 0.01% to about 2% by weight of other impurities, said apparatus comprising: A first distillation unit is configured to distill the crude mixture at a head pressure in the range of 20 mmHg to 100 mmHg to produce a first bottom stream and a first top stream, the first bottom stream containing ≤1 wt% 2-ethylbutadionitrile of the total first bottom stream mass, and the first top stream containing ≤1 wt% adiponitrile of the total first top stream mass. A second distillation unit is configured to distill the first bottom stream at a head pressure in the range of 20 mmHg to 100 mmHg to produce a second bottom stream, the second bottom stream containing ≥80% of 2-cyanocyclopentylimine present in the crude mixture, wherein the second distillation unit is configured to provide at least one of a second overhead stream and a side feed stream. An optional third distillation unit is configured to distill at least one of the second overhead stream and the side feed stream at a head pressure in the range of 10 mmHg to 80 mmHg to produce a third overhead stream and a third bottom stream, wherein the third overhead stream contains ≤0.1% by weight of 2-cyanocyclopentadiene imine of the total third overhead stream mass, and the third bottom stream contains ≤0.5% by weight of 2-ethylbutadionitrile of the total third bottom stream mass; and One or more flow channels are configured to combine a first overhead stream, a second bottom stream, and optionally a third bottom stream to form a tailings mixture, the tailings mixture comprising 2-cyanocyclopentadiene imine in the range of 1% to 30% by weight of the total tailings mixture mass. in The optional third distillation unit is not present, and the second overhead feed stream, the side feed stream, or a combination thereof is the purified 2-methylglutaronitrile, or The optional third distillation unit is present, and the overhead feed stream of the third column is the purified 2-methylglutaronitrile; and The purified 2-methylglutaronitrile comprises ≥99.1% by weight of 2-methylglutaronitrile, ≤0.5% by weight of 2-ethylbutadionitrile, ≤0.2% by weight of adiponitrile, ≤0.2% by weight of 2-cyanocyclopentylimine and ≤0.2% by weight of water.

2. The apparatus of claim 1, wherein the apparatus is capable of continuous operation with fewer than five interruptions in flow / year of the tailings mixture.

3. The apparatus of claim 1, wherein the optional third distillation unit is absent, and wherein the second overhead feed stream, the side feed stream, or a combination thereof is the purified 2-methylglutaronitrile.

4. The apparatus according to claim 3, wherein the second overhead feed stream is the purified 2-methylglutaronitrile.

5. The apparatus of claim 3, wherein the side feed stream is the purified 2-methylglutaronitrile.

6. The apparatus of claim 3, wherein the combination of the second overhead feed stream and the side feed stream is the purified 2-methylglutaronitrile.

7. The apparatus of claim 1, wherein the first distillation unit is configured such that the crude mixture is introduced into the upper half of the first distillation unit, and wherein the second distillation unit is configured such that the first bottom feed stream is introduced into the lower half of the second distillation unit.

8. The apparatus of claim 1, wherein the first distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 50 total theoretical distillation stages.

9. The apparatus of claim 1, wherein the second distillation unit comprises two or more packing sections, the two or more packing sections together providing an equivalent of at least 30 total theoretical distillation stages.

10. The apparatus of claim 1, wherein the first distillation unit is configured to pass process vapor from the top of the first distillation unit column to a first condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the first overhead feed and to provide a first non-condensable vapor purge material.

11. The apparatus of claim 1, wherein the second distillation unit is configured to pass process vapor from the top of the second distillation unit column to a second condenser maintained at a condensation temperature and condense the process vapor to provide a liquid as the second overhead feed and to provide a second non-condensable vapor purging material.

12. The apparatus of claim 1, further comprising a heat exchange device configured to cool the tailings mixture to a temperature of 40°C-60°C.

13. The apparatus of claim 1, wherein the first distillation unit is configured to distill the crude mixture at a head pressure in the range of 40 mmHg to 60 mmHg, and wherein the second distillation unit is configured to distill the first column bottom stream at a head pressure in the range of 40 mmHg to 60 mmHg.

14. The apparatus of claim 1, wherein the first distillation unit is configured to maintain its top and bottom temperatures in the ranges of 45°C-60°C and 190°C-205°C, respectively, and wherein the second distillation unit is configured to maintain its top and bottom temperatures in the ranges of 45°C-60°C and 190°C-205°C, respectively.

15. The apparatus of claim 1, wherein the second distillation unit is configured to provide the side feed stream from near the top section of the second distillation unit.

16. The apparatus of claim 1, wherein the third distillation unit is present, and wherein the third overhead feed stream is the purified 2-methylglutaronitrile.

17. The apparatus of claim 16, wherein the third distillation unit is configured to maintain the top and bottom temperatures therein within the ranges of 55°C-80°C and 160°C-190°C, respectively.

18. An apparatus for recovering purified material from a crude mixture, the apparatus comprising: A first distillation unit is configured to distill the crude mixture under head pressure to produce a first bottom stream and a first top stream. and A second distillation unit is configured to distill the first bottom stream under a pressure head to produce a second bottom stream, wherein the second distillation unit is configured to provide at least one of a second top stream and a side-draw stream. in The apparatus is used to recover purified hexamethyleneimine (HMI) from a crude mixture comprising about 80% to about 90% by weight of HMI, about 5% to about 15% by weight of n-hexylamine, about 0% to 5% by weight of water, about 0% to 5% by weight of cyclohexylamine, and about 0% to about 5% by weight of hexamethylenediamine (HMD). The head pressure of the first distillation unit is maintained in the range of 400 mmHg to 500 mmHg. The first bottom stream contains concentrated HMI containing HMD, and the first overhead stream contains n-hexylamine and optionally water. The head pressure of the second distillation unit is maintained in the range of 100 mmHg to 200 mmHg. The second bottom stream contains concentrated HMD containing HMI. The second overhead stream, the side feed stream, or a combination thereof is the purified material and is purified HMI, and the purified HMI is at least 99% by weight HMI, or... The apparatus is used to recover purified 1,2-diaminocyclohexane (DCH) from a crude mixture comprising about 65% to about 80% by weight of DCH, about 10% to about 20% by weight of hexamethylenediamine (HMD), about 0% to 5% by weight of hexamethyleneimine (HMI), about 0% to about 5% by weight of 2-(aminomethyl)-cyclopentanamine (AMC), about 0% to about 5% by weight of 2-methyl-pentamethylenediamine (MPMD), and about 0% to about 2% by weight of other impurities comprising n-hexylamine, cyclohexylamine, or combinations thereof, wherein the head pressure of the first distillation unit is maintained at 700 mmHg. Within the range of 850 mmHg, the first bottom stream contains concentrated DCH, optionally containing HMD, AMC, MPMD, or a combination thereof; the first overhead stream contains HMD and optionally contains AMC and MPMD; the second distillation unit head pressure is maintained within the range of 100 mmHg to 200 mmHg; the second bottom stream contains concentrated HMD containing DCH and optionally containing AMC, MPMD, or a combination thereof; the second overhead stream, the side feed stream, or a combination thereof is the purified material and is purified DCH; and the purified DCH is at least 98.5% by weight DCH.

19. The apparatus of claim 18, wherein the apparatus is used to recover purified hexamethyleneimine (HMI) from a crude mixture comprising about 80% to about 90% by weight of HMI, about 5% to about 15% by weight of n-hexylamine, about 0% to 5% by weight of water, about 0% to 5% by weight of cyclohexylamine, and about 0% to about 5% by weight of hexamethylenediamine (HMD), wherein the head pressure of the first distillation unit is maintained in the range of 400 mmHg to 500 mmHg, the first bottom stream comprises concentrated HMI containing HMD, the first overhead stream comprises n-hexylamine and optionally contains water, the head pressure of the second distillation unit is maintained in the range of 100 mmHg to 200 mmHg, the second bottom stream comprises concentrated HMD containing HMI, the second overhead stream, the side feed stream, or a combination thereof is the purified material and is purified HMI, and wherein the purified HMI is at least 99% by weight HMI.

20. The apparatus of claim 18, wherein the apparatus is used to recover purified 1,2-diaminocyclohexane (DCH) from a crude mixture comprising about 65 wt% to about 80 wt% of DCH, about 10 wt% to about 20 wt% of hexamethylenediamine (HMD), about 0 wt% to 5 wt% of hexamethyleneimine (HMI), about 0 wt% to about 5 wt% of 2-(aminomethyl)-cyclopentanamine (AMC), about 0 wt% to about 5 wt% of 2-methyl-pentamethylenediamine (MPMD), and about 0 wt% to about 2 wt% of other impurities comprising n-hexylamine, cyclohexylamine, or combinations thereof, wherein the pressure head of the first distillation unit is maintained at... The first bottom feed stream, maintained in the range of 700 mmHg to 850 mmHg, contains concentrated DCH, optionally containing HMD, AMC, MPMD, or a combination thereof; the first overhead feed stream contains HMD and optionally contains AMC and MPMD; the second distillation unit head pressure is maintained in the range of 100 mmHg to 200 mmHg; the second bottom feed stream contains concentrated HMD containing DCH and optionally containing AMC, MPMD, or a combination thereof; the second overhead feed stream, the side feed stream, or a combination thereof is the purified material and is purified DCH; and the purified DCH is at least 98.5% by weight DCH.

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