Preparation method and purification method of amine

Abstract

The invention relates to a method for producing amine and a method for purifying the amine. The purification method of the present invention comprises a step of contacting a crude amine containing an inorganic base and an aqueous inorganic base solution having an inorganic base content (in m%) of 10-70 times the inorganic base content (in m%) of the crude amine to obtain a purified amine. The purification method has the advantages that the separation efficiency is improved, the separation device is simplified, and the purification method is suitable for industrial continuous operation.

Description

Technical Field

[0001] The present invention relates to the field of material science and technology, and more particularly to a method for producing an amine and a method for purifying the amine. Background Art

[0002] Organic diamines are the primary raw materials for the synthesis of polyamide engineering plastics and hot-melt adhesives. They are crucial organic compounds and important intermediates for the preparation of natural products and pharmaceutical molecules. They are widely used in dyes, pharmaceuticals, pesticides, surfactants, and materials science. For example, hexamethylenediamine can be used in the production of nylon-6,6, and has a wide range of applications and a broad market.

[0003] As a method for producing diamines, the corresponding dinitrile compounds are often produced by catalytic hydrogenation under low pressure and temperature in the presence of a solvent. The catalyst is generally a skeletal nickel catalyst. During the reaction process, the fatty dinitrile compound is first hydrogenated to convert into an aminonitrile, which is further hydrogenated to convert into a fatty diamine compound. When fatty dinitrile compounds are used to prepare fatty diamine compounds, the corresponding secondary amines, tertiary amines, nitrogen-containing heterocyclic compounds, and deamination side reactions are easily generated during the hydrogenation of the aminonitrile. Therefore, it is necessary to add an appropriate amount of inorganic base co-catalyst during the nitrile hydrogenation process to prevent the occurrence of side reactions and ensure the smooth progress of the hydrogenation reaction. After the hydrogenation process is completed, the crude amine material containing strong inorganic bases needs to be separated or removed of the inorganic base before the hydrogenation product is purified, otherwise the crude amine purification will not proceed smoothly.

[0004] The strong inorganic base in the crude diamine system of the hydrogenation product has a great influence on the subsequent diamine separation, and the crude diamine needs to be treated to remove the inorganic base before distillation.

[0005] Patent CN201710894318 discloses a system and method for removing sodium hydroxide from hexamethylenediamine production. The patent describes a process in which the reaction liquid, after removing ethanol, enters a sodium hydroxide decanter. Within the decanter, the flow rate of the reaction liquid is reduced, providing a certain amount of rest time for the fluid. Because the sodium hydroxide solution has a higher specific gravity than hexamethylenediamine, at a certain temperature, the sodium hydroxide in the solution separates and precipitates at the bottom of the decanter, where it is then discharged through a discharge line. This separation method, which relies on differences in specific gravity for removal, is affected by changes in load and the rest time of the fluid, and the sodium hydroxide cannot be fully separated.

[0006] Patent CN202111598736 discloses a method for separating inorganic alkali from the hydrogenation product of decanedinitrile. It describes separating the catalyst by sedimentation filtration, then recovering ethanol by distillation or intermittent distillation, and performing two-phase separation by taking advantage of the fact that crude decanediamine and concentrated inorganic alkali solution are different phases with a large density difference. The separated crude decanediamine is then dehydrated and a small amount of inorganic alkali is separated by sedimentation. The inorganic alkali solution in this method has very little water content and high viscosity. The residual inorganic alkali is difficult to precipitate from the system and is in a viscous flocculent form, making separation difficult. Summary of the Invention

[0007] The inventors of the present invention discovered that the strong inorganic base in the crude amine system, the hydrogenation product, significantly affects subsequent amine separation, necessitating the removal of the inorganic base from the crude amine prior to distillation. To this end, through diligent research, the inventors discovered that mixing an inorganic base solution of a certain concentration with the crude amine containing the inorganic base can overcome these technical problems of the prior art. This discovery led to the present invention.

[0008] Specifically, the present invention relates to the following aspects.

[0009] 1. A method for purifying a crude amine, comprising a step (referred to as a contacting step) of contacting the crude amine with an aqueous solution of an inorganic base (preferably countercurrent contact) to obtain a refined amine, wherein the crude amine contains an inorganic base, and the inorganic base content of the aqueous solution of the inorganic base (in m%) is 10-70 times (preferably 25-50 times) the inorganic base content (in m%) of the crude amine.

[0010] 2. The purification method according to any one of the preceding or following aspects, wherein the crude amine has an inorganic base content of 0.2-2 wt%, preferably 0.4-1.0 wt%, based on the total mass of the crude amine as 100 wt%.

[0011] 3. The purification method according to any one of the preceding or following aspects, wherein the alcohol content of the crude amine is 0-0.2 wt%, preferably 0-0.05 wt%, based on the total mass of the crude amine as 100 wt%.

[0012] 4. The purification method according to any one of the preceding or following aspects, wherein the inorganic base content of the inorganic base aqueous solution is 10-45 wt%, preferably 15-35 wt%, based on the total mass of the inorganic base aqueous solution as 100 wt%.

[0013] 5. The purification method according to any one of the preceding or following aspects, wherein the inorganic base is an alkali metal hydroxide, preferably at least one selected from potassium hydroxide and sodium hydroxide.

[0014] 6. The purification method according to any of the preceding or following aspects, wherein the crude amine is selected from at least one of C2-C18 alkylamines and C2-C18 alkanediamines, preferably at least one of C6-C12 alkylamines and C6-C12 alkanediamines, and in particular at least one of hexylamine, 1,6-hexanediamine, dodecylamine and 1,12-dodecanediamine.

[0015] 7. The purification method according to any one of the preceding or following aspects, wherein the ratio of the mass flow rate of the crude amine to the mass flow rate of the inorganic base aqueous solution is 0.3-5:1, preferably 0.5-3:1.

[0016] 8. The purification method according to any one of the preceding or following aspects, wherein the inorganic base content of the refined amine is ≤150 mg / kg refined amine, preferably ≤50 mg / kg refined amine.

[0017] 9. The purification method according to any one of the preceding or following aspects, wherein the contacting step is performed in a liquid-liquid separation device, and the liquid-liquid separation device is selected from at least one of a liquid-liquid separation tower, a gravity separation device, and a centrifugal separation device.

[0018] 10. A method for producing an amine, comprising the following steps:

[0019] hydrogenating the nitrile in the presence of an alcohol to obtain a hydrogenated product,

[0020] At least a portion (preferably more than 98 m %, more preferably substantially all) of the alcohol is removed from the hydrogenation product to obtain a crude amine, and the crude amine is contacted with an aqueous solution of an inorganic base (preferably countercurrent contact) to obtain a refined amine, wherein the crude amine contains an inorganic base, and the inorganic base content of the aqueous solution of the inorganic base (in m %) is 10-70 times (preferably 20-50 times) the inorganic base content (in m %) of the crude amine.

[0021] Technical Effects

[0022] The patented method is characterized in that a concentrated inorganic alkali solution is mixed with the dealcoholized hydrogenated crude amine product, which can greatly improve the separation efficiency, simplify the separation device, and is suitable for industrial continuous operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the crude amine purification process. DETAILED DESCRIPTION

[0024] The specific embodiments of the present invention are described in detail below. However, it should be noted that the protection scope of the present invention is not limited by these specific embodiments, but is determined by the claims in the appendix.

[0025] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In the event of conflict, the definitions in this specification will prevail.

[0026] When this specification uses the prefix "well known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, the objects introduced by the prefix include those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become generally recognized in the art to be suitable for similar purposes.

[0027] In the context of this specification, by substantially it is meant that the deviation does not exceed 5%, preferably does not exceed 2% or 1%.

[0028] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on mass and pressure is gauge pressure.

[0029] In the context of this specification, if there are no specific operating conditions and additives, those known in the art are directly applicable without particular limitation.

[0030] In the context of this specification, any two or more embodiments of the present invention may be arbitrarily combined, and the technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the scope of protection of the present invention.

[0031] According to one embodiment of the present invention, a method for purifying a crude amine is provided. The crude amine generally has a purity of ≥90% (m / m), preferably ≥95% (m / m). Furthermore, the crude amine is generally obtained from a C2-C18 organic nitrile or organic dinitrile via a hydrogenation process. This hydrogenation process typically uses an inorganic base as an auxiliary agent and an alcohol as a solvent, resulting in the crude amine generally containing a certain amount of inorganic base and alcohol.

[0032] According to one embodiment of the present invention, the method for purifying crude amine includes a step of contacting the crude amine with an aqueous solution of an inorganic base to obtain the refined amine, which is referred to as a contacting step. The contacting step is preferably a countercurrent contacting step.

[0033] According to one embodiment of the present invention, the crude amine is selected from at least one of C2-C18 alkylamines and C2-C18 alkanediamines, preferably selected from at least one of C6-C12 alkylamines and C6-C12 alkanediamines, in particular selected from at least one of hexylamine, 1,6-hexanediamine, dodecylamine and 1,12-dodecanediamine.

[0034] According to one embodiment of the present invention, the crude amine generally has an inorganic base content of 0.2-2 wt%, preferably 0.4-1.0 wt%, based on the total mass of the crude amine as 100 wt%. The base is derived from the process of preparing the crude amine by hydrogenation of nitrile. According to the method of the present invention, the base content in the crude amine is reduced to 150 ppm, preferably below 50 ppm, thereby eliminating the impact of the base in the subsequent crude amine distillation unit and easing the process operating conditions of the crude amine distillation unit. If the base content in the crude amine is greater than 150 ppm, the base will be adsorbed on the internal structures of the distillation equipment during the crude amine distillation process, reducing the distillation efficiency of the crude amine and hindering the distillation process of the crude amine.

[0035] According to one embodiment of the present invention, the crude amine has an alcohol content of 0-0.2% by mass, preferably 0-0.05% by mass, based on 100% by mass of the crude amine. According to the present invention, the alcohol is generally derived from the crude amine production process. The alcohol is derived from the process for preparing the crude amine by hydrogenation of nitrile. According to the present method, the alcohol content in the crude amine is reduced to 0.2%, preferably below 0.05%. A high alcohol content in the crude amine will impair the alkali separation efficiency of the crude amine in the present method.

[0036] According to one embodiment of the present invention, the inorganic alkali aqueous solution has an inorganic alkali content of 10-45 wt%, preferably 15-35 wt%, based on 100 wt% of the total mass of the inorganic alkali aqueous solution.

[0037] According to one embodiment of the present invention, the inorganic base is an alkali metal hydroxide, preferably at least one selected from potassium hydroxide and sodium hydroxide.

[0038] According to one embodiment of the present invention, the inorganic alkali content of the inorganic alkali aqueous solution (in m%) is 10-70 times (preferably 20-50 times) the inorganic alkali content of the crude amine (in m%). If the inorganic alkali content of the inorganic alkali water is less than 10 times the inorganic alkali content of the crude amine, the interface between the crude amine solution and the inorganic alkali aqueous solution will be unclear, the inorganic alkali removal will not meet the requirements, and the inorganic alkali content of the refined amine will be unqualified. If the inorganic alkali content of the inorganic alkali water is greater than 70 times the inorganic alkali content of the crude amine, the concentration of the inorganic alkali in the inorganic alkali aqueous solution will be close to or reach saturation, resulting in low efficiency of separation and removal of inorganic alkali until the inorganic alkali in the crude amine cannot be extracted.

[0039] According to one embodiment of the present invention, the inorganic base content of the refined amine is made ≤150 mg / kg refined amine, preferably ≤50 mg / kg refined amine, by the contacting.

[0040] According to one embodiment of the present invention, the contacting step is performed in a liquid-liquid separation device, wherein the liquid-liquid separation device is selected from at least one of a liquid-liquid separation tower, a gravity separation device, and a centrifugal separation device.

[0041] According to one embodiment of the present invention, the liquid-liquid separation tower can be any type conventionally known in the art, such as an extraction tower, without particular limitation. Furthermore, the interior of the liquid-liquid separation tower can be filled with different types of fillers to effectively separate the desired components. Generally, the separation tower has an effective number of separation stages of 3-20, preferably 7-15.

[0042] According to one embodiment of the present invention, the gravity separation device or the centrifugal separation device can use any type conventionally known in the art, without particular limitation. Generally speaking, the effective separation stage number of the gravity separation device or the centrifugal separation device is 2-10, preferably 3-5.

[0043] According to one embodiment of the present invention, the ratio of the mass flow rate of the crude amine to the mass flow rate of the inorganic alkali aqueous solution is 0.3-5:1, preferably 0.5-3:1. Here, the mass flow rate refers to the mass flow rate of the crude amine or the inorganic alkali aqueous solution immediately before the contacting, such as the mass flow rate of the crude amine or the inorganic alkali aqueous solution at the inlet of the liquid-liquid separation device. If the ratio of the mass flow rate of the crude amine to the mass flow rate of the inorganic alkali aqueous solution is less than 0.3:1 or greater than 5:1, the spermine base content after treatment may be too high.

[0044] According to one embodiment of the present invention, the operating conditions of the contacting step include: temperature 80-100° C., and contact time 30-180 min.

[0045] According to one embodiment of the present invention, a method for producing an amine is provided. In the following method for producing an amine, if there is no clear content, the content described above in the purification method of the crude amine can be directly applied, and no further details are given here.

[0046] According to one embodiment of the present invention, the method for producing amine comprises the following steps: hydrogenating nitrile in the presence of alcohol to obtain a hydrogenated product, and removing at least a portion of the alcohol from the hydrogenated product to obtain a crude amine.

[0047] According to the present invention, the hydrogenation and alcohol removal steps can be carried out in any manner known in the art without particular limitation. In addition, by removing the alcohol, the alcohol content of the crude amine meets the aforementioned requirements of the present invention.

[0048] According to the present invention, the method for producing amine further comprises a step (contacting step) of contacting the crude amine with an aqueous inorganic base solution to obtain a refined amine. Here, the contacting step can be performed according to any of the aforementioned embodiments of the present invention.

[0049] The present invention will be further described in detail below with reference to the accompanying drawings, but the present invention is not limited to the accompanying drawings.

[0050] according to Figure 1 The crude amine material enters the lower middle part of the No. 4 separation unit from Line 1 in liquid phase at a certain temperature. The inorganic alkali aqueous solution circulates from the upper middle part of the No. 3 separation unit at a certain flow rate in Line 2. The crude inorganic amine material and the inorganic alkali circulating solution come into countercurrent contact inside the separation unit, and the crude amine is purified. The purified refined amine with the inorganic alkali separated flows out from Line 5 at the top of the separation unit. The slightly concentrated inorganic alkali solution obtained from the lower part of the separation unit enters the inorganic alkali solution storage tank. The inorganic alkali solution from the No. 7 inorganic alkali solution storage tank is circulated all the way to the No. 3 separation unit, all the way to the No. 4 alkali unit, and a small amount is discharged from Line 6 to maintain the balance of alkali and impurity content in the inorganic alkali solution.

[0051] Example

[0052] The present invention is further described in detail below with reference to examples, but the present invention is not limited to these examples.

[0053] Example 1

[0054] Crude dodecyldiamine containing 0.5% KOH enters the lower portion of an extraction separation column at 90°C in the liquid phase at a rate of 50 kg / hr. The theoretical separation stage of the extraction column is 9. A 20% KOH circulating solution enters the upper portion of the separation column at a rate of 45 kg / hr. The inorganic base content of the KOH aqueous solution is 40 times that of the crude dodecyldiamine. The mass flow rate ratio of the crude dodecyldiamine to the inorganic base aqueous solution is 0.9. The crude dodecyldiamine containing the inorganic base and the KOH circulating solution are in countercurrent contact within the extraction separation column for a residence time of 40 minutes. The crude dodecyldiamine is purified, and the purified refined dodecyldiamine containing 35 mg / kg of KOH flows out of the top of the extraction separation column.

[0055] Example 2

[0056] Crude dodecyldiamine containing 0.5% KOH was introduced into the lower portion of an extraction and separation tower at a temperature of 90°C in the liquid phase at a rate of 50 kg / hr. The theoretical separation stage of the extraction tower was 9. A 30% KOH inorganic base circulating solution was introduced into the upper portion of the extraction and separation tower at a rate of 150 kg / hr. The inorganic base content of the aqueous solution was 60 times that of the crude dodecyldiamine. The mass flow rate ratio of the crude dodecyldiamine to the aqueous solution was 3.0. The crude dodecyldiamine containing KOH and the circulating solution were in countercurrent contact within the extraction and separation tower for a residence time of 40 minutes. The crude dodecyldiamine was purified, and the purified refined dodecyldiamine, containing 59 mg / kg of KOH, flowed out of the top of the extraction and separation tower.

[0057] Example 3

[0058] Crude dodecyldiamine containing 0.5% KOH enters the lower portion of an extraction separation column at 90°C in the liquid phase at a rate of 50 kg / hr. The theoretical separation stage of the extraction column is 9. A 15% KOH inorganic base circulating solution enters the upper portion of the extraction separation column at a rate of 150 kg / hr. The inorganic base content of the KOH inorganic base solution is 30 times that of the crude dodecyldiamine. The mass flow rate ratio of the crude dodecyldiamine to the inorganic base aqueous solution is 3.0. The crude dodecyldiamine inorganic base feed and the KOH inorganic base circulating solution contact each other in countercurrents within the extraction separation column for a residence time of 40 minutes. The crude dodecyldiamine is purified, and the purified refined dodecyldiamine containing 50 mg / kg of inorganic base flows out of the top of the extraction separation column.

[0059] Example 4

[0060] The same conditions as in Example 3 were followed, except that the theoretical separation stage number of the extraction column was replaced with 4. The purified dodecanediamine containing 83 mg / kg of inorganic base flowed out from the top of the separation device.

[0061] Example 5

[0062] Crude dodecyldiamine containing 0.3% KOH was introduced into the lower portion of an extraction separation column at a temperature of 90°C in the liquid phase at a rate of 50 kg / hr. The theoretical separation stage of the extraction column was 9. A 10% KOH circulating solution was introduced into the upper portion of the extraction separation column at a rate of 20 kg / hr. The inorganic base content of the KOH aqueous solution was 10 times that of the crude dodecyldiamine, and the mass flow rate ratio of the crude dodecyldiamine to the inorganic base aqueous solution was 0.4. The crude dodecyldiamine and the KOH circulating solution were in countercurrent contact within the extraction separation column for a residence time of 40 minutes. The crude dodecyldiamine was purified, and the purified refined dodecyldiamine, containing 115 mg / kg of inorganic base, flowed out of the top of the extraction separation column.

[0063] Example 6

[0064] Under the same conditions as in Example 3, the KOH concentration was 40%, and the purified refined dodecanediamine contained 73 mg / kg of inorganic base and flowed out from the top of the separation device.

[0065] Example 7

[0066] Under the same conditions as in Example 3, the KOH concentration was 45%, and the purified refined dodecanediamine contained 127 mg / kg of inorganic base and flowed out from the top of the separation device.

[0067] Example 8

[0068] Crude dodecyldiamine containing 1.5% inorganic base KOH enters the lower portion of an extraction and separation column at 90°C in the liquid phase at a rate of 60 kg / hr. The theoretical separation stage of the extraction column is 9. A 25% KOH inorganic base circulating solution enters the upper portion of the extraction and separation column at a rate of 45 kg / hr. The inorganic base content of the KOH inorganic base aqueous solution is 12.5 times that of the crude dodecyldiamine. The mass flow rate ratio of the crude dodecyldiamine to the inorganic base aqueous solution is 0.75. The crude dodecyldiamine and the KOH inorganic base circulating solution contact each other in countercurrents within the extraction and separation column for a residence time of 40 minutes. The crude dodecyldiamine is purified, and the purified refined dodecyldiamine, containing 66 mg / kg of inorganic base, flows out of the top of the extraction and separation column.

[0069] Example 9

[0070] Crude dodecyldiamine containing 1.0% KOH inorganic base was introduced into the lower portion of an extraction separation column at a temperature of 90°C in the liquid phase at a rate of 50 kg / hr. The theoretical separation stage of the extraction column is 9. A 25% KOH inorganic base circulating solution was introduced into the upper portion of the extraction separation column at a rate of 85 kg / hr. The inorganic base content of the KOH inorganic base aqueous solution was 25 times that of the crude dodecyldiamine. The mass flow rate ratio of the crude dodecyldiamine to the inorganic base aqueous solution was 1.7. The crude dodecyldiamine containing inorganic base and the KOH inorganic base circulating solution were in countercurrent contact within the extraction separation column for a residence time of 40 minutes. The crude dodecyldiamine was purified, and the purified refined dodecyldiamine containing 37 mg / kg of inorganic base flowed out from the top of the extraction separation column.

[0071] Example 10

[0072] The same conditions as in Example 7 were followed, except that the inorganic base KOH was replaced by NaOH. The purified refined dodecanediamine contained 39 mg / kg of inorganic base and flowed out from the top of the extraction separation tower.

[0073] Example 11

[0074] Crude dodecyldiamine containing 0.5% KOH inorganic base is fed into the lower portion of an extraction separation column at a temperature of 90°C in the liquid phase at a rate of 50 kg / hr. The theoretical separation stage of the extraction column is 9. A 15% KOH inorganic base circulating solution is fed into the upper portion of the extraction separation column at a rate of 35 kg / hr. The inorganic base content of the KOH inorganic base aqueous solution is 30 times that of the crude dodecyldiamine. The mass flow rate ratio of the crude dodecyldiamine to the KOH inorganic base aqueous solution is 0.7. The crude dodecyldiamine containing KOH and the inorganic base circulating solution are in countercurrent contact within the extraction separation column for a residence time of 70 minutes. The crude dodecyldiamine is purified, and the purified refined dodecyldiamine containing 47 mg / kg of inorganic base flows out of the top of the separation device.

[0075] Example 12

[0076] Crude dodecyldiamine containing 1.0% KOH inorganic base was introduced into the lower portion of an extraction separation column at a temperature of 90°C in the liquid phase at a rate of 50 kg / hr. The theoretical separation stage of the extraction column is 9. A 25% KOH inorganic base circulating solution was introduced into the upper portion of the extraction separation column at a rate of 45 kg / hr. The inorganic base content of the KOH inorganic base aqueous solution was 25 times that of the crude dodecyldiamine. The mass flow rate ratio of the crude dodecyldiamine to the inorganic base aqueous solution was 0.9. The crude dodecyldiamine containing inorganic base and the inorganic base circulating solution were in countercurrent contact within the separation device for a residence time of 90 minutes. The crude dodecyldiamine was purified, and the purified refined dodecyldiamine containing 31 mg / kg of inorganic base flowed out from the top of the separation device.

[0077] Example 13

[0078] The same conditions as in Example 10 were followed, except that the 1.0% KOH inorganic base crude dodecanediamine was replaced with 1.0% KOH inorganic base crude decanediamine. The purified decanediamine contained 34 mg / kg of inorganic base and flowed out from the top of the extraction separation tower.

[0079] Example 14

[0080] The same conditions as in Example 10 were followed, except that the extraction separation column was replaced with a three-stage centrifugal separation device. The purified decanediamine containing 96 mg / kg of inorganic base flowed out as a light phase from the last stage of the centrifugal separation device.

[0081] Example 15

[0082] Under the same conditions as in Example 1, the crude dodecanediamine contained 0.015% alcohol, and the purified refined dodecanediamine contained 49 mg / kg of inorganic base and flowed out from the top of the extraction separation tower.

[0083] Example 16

[0084] Under the same conditions as in Example 1, the crude dodecanediamine contained 0.17% alcohol, and the purified refined dodecanediamine contained 109 mg / kg of inorganic base and flowed out from the top of the extraction separation tower.

[0085] Comparative Example 1

[0086] Crude dodecyl diamine containing 0.5% KOH inorganic base is fed into the upper portion of a de-alkali stabilization tank at 90°C in liquid phase at a rate of 50 kg / hr. A 20% KOH inorganic base solution is placed in the lower portion of the tank. The crude dodecyl diamine resides in the tank for 2 hours, based on the crude feed. Refined dodecyl diamine is discharged from the opposite side of the tank at a rate of 50 kg / hr. A baffle is installed in the tank to prevent back-mixing of the crude amine. After de-alkali separation, the refined amine, purified and separated, contains 250 mg / kg of inorganic base.

[0087] Comparative Example 2

[0088] Crude dodecanediamine containing 0.5% KOH inorganic base was fed into a static mixer at 90°C in liquid phase at a rate of 50 kg / hr. A 20% KOH inorganic base solution was also fed into the static mixer at a rate of 45 kg / hr. The mixed material then entered a static tank for removing the inorganic base. Purified, refined dodecanediamine was discharged from the upper portion of the static tank at a rate of 50 kg / hr, while the inorganic base solution was discharged from the lower portion of the static tank at a rate of 45 kg / hr. Analysis revealed that the purified, separated, refined dodecanediamine contained 210 mg / kg of inorganic base.

[0089] Comparative Example 3

[0090] The same conditions as in Example 1 were followed, except that the 20% inorganic base circulating solution was replaced with pure water. Analysis revealed that the purified amine contained 850 mg / kg of inorganic base.

[0091] Comparative Example 4

[0092] According to the same conditions as Example 1, only the 20% concentration of the inorganic base circulating solution is replaced by a 4% concentration of the inorganic base circulating solution. As a result, the inorganic base content of the inorganic base aqueous solution is 8 times the inorganic base content of the crude amine, and the inorganic base content of the refined amine after purification and separation is 377 mg / kg.

[0093] Comparative Example 5

[0094] According to the same conditions as in comparative example 1, only the 20% concentration inorganic base circulating solution was replaced by a 50% concentration inorganic base circulating solution. As a result, the inorganic base content of the inorganic base aqueous solution was 100 times that of the crude amine, and the inorganic base content of the refined amine after purification and separation was 257 mg / kg.

Claims

1. A method for purifying a crude amine, comprising a step (referred to as a contacting step) of contacting the crude amine with an aqueous solution of an inorganic base (preferably countercurrent contact) to obtain a refined amine, wherein the crude amine contains an inorganic base, and the inorganic base content of the aqueous solution of the inorganic base (in m%) is 10-70 times (preferably 25-50 times) the inorganic base content (in m%) of the crude amine.

2. The purification method according to claim 1, wherein the inorganic base content of the crude amine is 0.2-2 wt%, preferably 0.4-1.0 wt%, based on the total mass of the crude amine as 100 wt%.

3. The purification method according to claim 1, wherein the alcohol content of the crude amine is 0-0.2 wt%, preferably 0-0.05 wt%, based on the total mass of the crude amine as 100 wt%.

4. The purification method according to claim 1, wherein the inorganic alkali content of the inorganic alkali aqueous solution is 10-45 wt%, preferably 15-35 wt%, based on the total mass of the inorganic alkali aqueous solution as 100 wt%.

5. The purification method according to claim 1, wherein the inorganic base is an alkali metal hydroxide, preferably at least one selected from potassium hydroxide and sodium hydroxide.

6. The purification method according to claim 1, wherein the crude amine is selected from at least one of C2-C18 alkylamines and C2-C18 alkanediamines, preferably selected from at least one of C6-C12 alkylamines and C6-C12 alkanediamines, and in particular selected from at least one of hexylamine, 1,6-hexanediamine, dodecylamine and 1,12-dodecanediamine.

7. The purification method according to claim 1, wherein the ratio of the mass flow rate of the crude amine to the mass flow rate of the inorganic base aqueous solution is 0.3-5:1, preferably 0.5-3:

1.

8. The purification method according to claim 1, wherein the contacting step is performed in a liquid-liquid separation device, and the liquid-liquid separation device is selected from at least one of a liquid-liquid separation tower, a gravity separation device, and a centrifugal separation device.

9. A method for producing an amine, comprising the following steps: hydrogenating the nitrile in the presence of an alcohol to obtain a hydrogenated product, At least a portion (preferably more than 98 m %, more preferably substantially all) of the alcohol is removed from the hydrogenation product to obtain a crude amine, and the crude amine is contacted with an aqueous solution of an inorganic base (preferably countercurrent contact) to obtain a refined amine, wherein the crude amine contains an inorganic base, and the inorganic base content of the aqueous solution of the inorganic base (in m %) is 10-70 times (preferably 20-50 times) the inorganic base content (in m %) of the crude amine.

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