Method for synthesizing hexamethylenediamine and co-producing hexamethyleneimine

Abstract

The invention relates to a method for synthesizing hexamethylenediamine and co-producing hexamethyleneimine, which comprises the following steps of: feeding an adiponitrile-containing raw material and hydrogen into a tube pass of a shell and tube reactor, contacting with an activated adiponitrile hydrogenation catalyst, reacting under the condition of adiponitrile hydrogenation reaction, separating the obtained reaction effluent, and separating to obtain the hexamethylenediamine and cyclohexyleneimine. At least a hexamethylenediamine product and a hexamethyleneimine product are obtained. The process route is simple and optimized, the operation is simple, convenient and safe, the continuous production can be realized, the cost is low, and the product yield is high.

Description

Technical Field

[0001] The invention relates to the field of preparing hexamethylenediamine by hydrogenating adiponitrile, and in particular to a method for synthesizing hexamethylenediamine and co-producing cycloheximide. Background Art

[0002] Hexamethylenediamine is an important chemical raw material, which can be used to synthesize nylon 66, nylon 610, hexamethylene diisocyanate, etc. Among them, 90% of hexamethylenediamine is used to synthesize nylon salt and then produce nylon 66. Nylon-66 is mainly used to produce engineering plastics and fiber products. Its plastic products have strong tensile strength and weather resistance, and can replace traditional metal materials for the production of mechanical parts, mechanical force components, etc. At present, the methods for industrial production of hexamethylenediamine mainly include low-pressure fluidized bed method and high-pressure fixed bed method. Patent US3821305 discloses the use of Raney nickel for hydrogenation of adiponitrile to prepare hexamethylenediamine. The reaction device is a three-phase fluidized bed. The catalyst particle size in the reaction is about 20-50μm, which is difficult to separate and has a high degree of wear on the device. At the same time, waste alkali liquid is generated, which is difficult to handle and causes great environmental pollution.

[0003] CN106536476B discloses a method and system for preparing hexamethylenediamine using a high-pressure fixed bed, wherein an iron-based catalyst is used in the process and the pressure is higher than 27 MPa.

[0004] Cycloheximide is also an important intermediate. It can be used as a pesticide intermediate to synthesize a variety of carbamate herbicides, and can also be used to prepare cycloheximide penicillin and anti-neuropathy drugs. There are three main methods for preparing cycloheximide: the first is to use aniline as a raw material and produce cycloheximide through hydrogenation reaction; the second is to use caprolactam as a raw material, and CN112079726B discloses this production method; the third is to use hexamethylenediamine as a raw material, and hexamethylenediamine can be deaminated and cyclized to obtain the target product.

[0005] In the prior art, 1,2-diaminocyclohexane (DCH) and aminomethylcyclopentylamine (AMCPA) are common impurities in hexamethylenediamine products. Diamine impurities have a similar boiling point to hexamethylenediamine, and the diamine impurities produced in the reaction will increase the cost of subsequent product separation. The content of trans-1,2-diaminocyclohexane is one of the important indicators of industrial 1,6-hexamethylenediamine. According to the standard "HG / T3937-2021", the content of trans-1,2-diaminocyclohexane in superior hexamethylenediamine is ≤10mg / kg, the content of trans-1,2-diaminocyclohexane in first-class hexamethylenediamine is ≤18mg / kg, and the content of trans-1,2-diaminocyclohexane in qualified hexamethylenediamine is ≤30mg / kg. Summary of the invention

[0006] The object of the present invention is to provide a method for synthesizing hexamethylenediamine and producing cycloheximide on the basis of the prior art, comprising:

[0007] (1) an adiponitrile raw material, an ethanol solvent, and hydrogen enter a mixer together to obtain a uniformly mixed gas-liquid mixture, wherein the mass concentration of adiponitrile in the mixture of the adiponitrile raw material and the ethanol solvent is 10 to 99%;

[0008] (2) the gas-liquid mixture enters the tube side of the shell-and-tube reactor, contacts with the activated adiponitrile hydrogenation catalyst, and reacts under adiponitrile hydrogenation reaction conditions. A cooling medium is used in the shell side of the shell-and-tube reactor to control the reaction temperature in the tube side within a certain range.

[0009] The reaction conditions for adiponitrile hydrogenation are: reaction temperature of 65-125°C, hydrogen partial pressure of 2-10 MPa, liquid hourly mass space velocity of adiponitrile of 0.1-10 h -1 , the molar ratio of hydrogen to adiponitrile is 50 to 500,

[0010] The adiponitrile hydrogenation catalyst comprises an active component of nickel, an additive 1 and an additive 2, wherein the content of nickel is 25 to 90% by weight, the content of the additive 1 is 0.1 to 30% by weight, and the content of the additive 2 is 5 to 50% by weight, based on the dry weight of the catalyst, and calculated as oxide, wherein the additive 1 is selected from at least one of the metal elements of the IIA group, and the additive 2 is selected from at least one of the lanthanide metal elements;

[0011] (3) The reaction effluent obtained in step (2) enters a high-pressure separator to separate a hydrogen-rich gas and a first liquid material. The first liquid material enters a low-pressure separator for further gas-liquid separation to obtain a second liquid material. The second liquid material enters a deethanolation tower, a first deweighting tower, and a product distillation tower in sequence to separate a cycloheximide product and a hexamethylenediamine product.

[0012] In one embodiment of the present invention, the mass concentration of adiponitrile in the mixture of adiponitrile raw material and ethanol solvent is 30-70%.

[0013] In one embodiment of the present invention, in step (3), the ethanol obtained from the deethanolation tower is recycled as an ethanol solvent.

[0014] The tube side of the shell-and-tube reactor is composed of a plurality of reaction tubes. In one embodiment of the present invention, in the shell-and-tube reactor, the aspect ratio of a single shell-and-tube is in the range of 10 to 200, and the diameter of a single shell-and-tube is in the range of 10 to 100 mm.

[0015] In one embodiment of the present invention, the shape of the adiponitrile hydrogenation catalyst is one or more selected from the group consisting of spherical, annular, cylindrical, butterfly and clover-shaped; preferably spherical.

[0016] In one embodiment of the present invention, the packing ratio of the adiponitrile hydrogenation catalyst is 0.5 to 1.2 kg / L.

[0017] In one embodiment of the present invention, the cooling medium is at least one of molten salt, heat transfer oil and water. In the present invention, the flow mode of the shell side cooling medium is cross flow or parallel flow.

[0018] In one embodiment of the present invention, the flow direction of the logistics in the tube pass of the tube reactor is that the gas and liquid flow in parallel from top to bottom, and the liquid phase reactants in the tube are in a trickle flow state.

[0019] In one embodiment of the present invention, the adiponitrile hydrogenation catalyst is activated in a reducing gas atmosphere to obtain an activated adiponitrile hydrogenation catalyst, and the activation treatment conditions are: pressure 0.5-8.0 MPa, temperature 120-450° C., and gas hourly volume space velocity of the reducing gas of 200-20000 h -1 The activation treatment time is 12 to 120 hours, and the reducing gas contains hydrogen and an optional protective gas, wherein the protective gas is nitrogen and / or water vapor.

[0020] In a preferred embodiment of the present invention, in the adiponitrile hydrogenation catalyst, based on the dry weight of the catalyst and calculated as oxide, the nickel content is 40-85% by weight, the additive 1 content is 4-25% by weight, and the additive 2 content is 10-45% by weight.

[0021] In a preferred embodiment of the present invention, the auxiliary agent 1 is selected from one or more of magnesium, calcium and barium, and the auxiliary agent 2 is selected from lanthanum and / or cerium.

[0022] In one embodiment of the present invention, the adiponitrile hydrogenation catalyst is prepared by a co-precipitation method.

[0023] In one embodiment of the present invention, a mixed solution of a nickel precursor, a precursor of auxiliary agent 1 and a precursor of auxiliary agent 2 is mixed with a precipitant for precipitation and aging, and the obtained precipitate is washed, dried, calcined and granulated to obtain an adiponitrile hydrogenation catalyst.

[0024] In one embodiment of the present invention, the precursors of nickel, additive 1 and additive 2 are independently selected from one or more of nitrates, acetates and chlorides of nickel, additive 1 and additive 2.

[0025] In one embodiment of the present invention, the solvent for dissolving the nickel precursor, the precursor of the auxiliary agent 1 and the precursor of the auxiliary agent 2 is selected from deionized water or anhydrous ethanol.

[0026] In one embodiment of the present invention, the precipitant is one selected from oxalic acid, ammonium carbonate, sodium carbonate and / or sodium hydroxide.

[0027] In one embodiment of the present invention, the precipitation temperature is 20-80° C., and the precipitation time is 0.5-5 h; preferably, the precipitation temperature is 25-40° C., and the precipitation time is 1-3 h.

[0028] In one embodiment of the present invention, the drying temperature is 60-150° C., and the drying time is 5-25 hours; preferably, the drying temperature is 80-120° C., and the drying time is 8-20 hours.

[0029] In one embodiment of the present invention, the calcination temperature is 200-500° C., and the calcination time is 1-10 h; preferably, the calcination temperature is 300-450° C., and the calcination time is 1.5-8 h.

[0030] In one embodiment of the present invention, the hydrogen-rich gas separated by the high-pressure separator is circulated to the inlet of the mixer for recycling.

[0031] In one embodiment of the present invention, the gas phase material separated by the low-pressure separator is treated by the discharge gas treatment system and then discharged or enters the hydrogen pressure swing adsorption purification system (PSA).

[0032] In one embodiment of the present invention, in step (3), the second liquid material enters the deethanol tower, ethanol is extracted from the top of the deethanol tower, and it can be recycled as an ethanol solvent. The bottom material of the deethanol tower enters the first deweighting tower, and the top material of the first deweighting tower includes a product mixture of hexamethylenediamine and cycloheximine. The bottom of the first deweighting tower obtains a high-boiling point product including dihexamethylenetriamine. The top material of the first deweighting tower enters the product distillation tower, and the cyclohexamethyleneimine product is extracted from the top of the product distillation tower, and the hexamethylenediamine product is extracted from the bottom of the tower. The content of the obtained cyclohexamethyleneimine (HMI) product and hexamethylenediamine (HMD) product is higher than 99.99%, wherein the mass ratio of hexamethylenediamine to cyclohexamethyleneimine is greater than or equal to 2. At the same time, at normal temperature and pressure (standard atmospheric pressure, 25°C), the 1,2-diaminocyclohexane (DCH) and aminomethylcyclopentylamine (AMCPA) in the obtained cyclohexamethyleneimine product and hexamethylenediamine product are both less than or equal to 10ppm.

[0033] In one embodiment of the present invention, step (3) includes a second de-weighting tower. When the high-boiling-point product obtained at the bottom of the first de-weighting tower contains a large amount of incompletely reacted raw materials and intermediate products, the bottom material of the first de-weighting tower enters the second de-weighting tower for separation, and the high-boiling-point products such as dihexylene triamine are obtained at the bottom of the second de-weighting tower, which are directly discharged from the device. The top material of the second de-weighting tower is unreacted adiponitrile (ADN) and incompletely reacted intermediate product aminocapronitrile (ACN), which are circulated to the mixer inlet as circulating materials, mixed with fresh unreacted liquid materials, and then enter the shell-and-tube reactor for reaction.

[0034] In one embodiment of the present invention, in step (3), the number of theoretical plates of the ethanol removal tower is 12 to 25; the number of theoretical plates of the first deweighting tower is 15 to 30; and the number of theoretical plates of the product distillation tower is 16 to 25.

[0035] In one embodiment of the present invention, the operating conditions of the deethanolation tower are: the tower top pressure is 50-101 KPa absolute pressure, the tower top temperature is 60-80° C., and the reflux ratio is 0.2-20;

[0036] In one embodiment of the present invention, the operating conditions of the first deweighting tower are: the tower top pressure is 10-50 KPa absolute pressure, the tower top temperature is 100-150° C., and the reflux ratio is 0.3-30;

[0037] In one embodiment of the present invention, the operating conditions of the product distillation tower are: tower top pressure of 5-50 KPa absolute pressure, tower top temperature of 55-115° C., and reflux ratio of 1-20.

[0038] In one embodiment of the present invention, the number of theoretical plates of the second deweighting tower is 10 to 25;

[0039] In one embodiment of the present invention, the operating conditions of the second deweighting tower are: tower top pressure 0.5-3 KPa absolute pressure, tower top temperature 75-100° C., and reflux ratio 0.05-10.

[0040] The present invention is characterized by:

[0041] (1) The present invention provides a hydrogenation method for synthesizing hexamethylenediamine, which can simultaneously continuously and stably produce cycloheximide. The technical scheme of the present invention is simple and optimized, the operation is simple and safe, the cost is low, and the raw material conversion rate is high and the target product selectivity is high.

[0042] (2) The present invention adopts a shell-and-tube reactor and uses a cooling medium to remove the heat released by the reaction and maintain the reaction temperature within a certain range. On the one hand, it is easy to adjust the product ratio by adjusting the reaction temperature. On the other hand, it is also easy to keep the reaction temperature constant during the reaction process, which is conducive to obtaining the target product with high selectivity over a long period of time.

[0043] (3) In the present invention, hexamethylenediamine is separated from high-boiling-point products as early as possible during the product separation process, thereby reducing the contamination of the hexamethylenediamine product by the high-boiling-point products during the separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The present invention provides a schematic flow chart of one embodiment of the method for synthesizing hexamethylenediamine and producing cycloheximide.

[0045] Figure 2The present invention provides a schematic flow chart of another embodiment of the method for synthesizing hexamethylenediamine and co-producing cycloheximide. DETAILED DESCRIPTION

[0046] The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited thereby.

[0047] Figure 1 The figure is a schematic diagram of a process for synthesizing hexamethylenediamine and producing cycloheximide according to one embodiment of the present invention. Figure 1 As shown, the adiponitrile raw material and the ethanol solvent enter the mixer 3 through pipeline 1, together with the fresh hydrogen from pipeline 2 and the circulating hydrogen from pipeline 23, to obtain a uniformly mixed gas-liquid mixture, and enter the tube process of the tubular reactor 5 through pipeline 4, contact with the activated adiponitrile hydrogenation catalyst, and react under the adiponitrile hydrogenation reaction conditions. The resulting reaction effluent enters the high-pressure separator 7 through pipeline 6, and the hydrogen-rich gas obtained by separation enters the circulating hydrogen compressor 22 through pipeline 8, and is sent to the inlet of the mixer 3 through pipeline 23 after being pressurized; the first liquid material separated by the high-pressure separator 7 enters the low-pressure separator 10 through pipeline 9 for further gas-liquid separation, and the obtained low-pressure gas is extracted through pipeline 11, and the second liquid material obtained by separation enters the deethanol tower 13 through pipeline 12, and ethanol is obtained at the top of the deethanol tower 13, which is sent to the inlet of the mixer 3 for recycling as an ethanol solvent through pipeline 14, and the bottom material of the deethanol tower 13 enters the first deweighting tower 16 through pipeline 15. The top material of the first de-weighting tower 16 mainly contains cycloheximide and hexamethylenediamine, and enters the product distillation tower 19 through pipeline 17. The cycloheximide product is extracted from the top of the product distillation tower 19 through pipeline 20, and the hexamethylenediamine product is extracted from the bottom of the tower through pipeline 21. The bottom material of the first de-weighting tower 16 is directly discharged from the device through pipeline 18.

[0048] Figure 2 FIG. 2 is a schematic diagram of another embodiment of the process of synthesizing hexamethylenediamine and producing cycloheximide provided by the present invention. Figure 2As shown, the adiponitrile raw material and the ethanol solvent enter the mixer 3 through pipeline 1, together with the fresh hydrogen from pipeline 2, the circulating hydrogen from pipeline 23, and the circulating liquid phase material from pipeline 25, to obtain a uniformly mixed gas-liquid mixture, and enter the tube process of the tubular reactor 5 through pipeline 4, contact with the activated adiponitrile hydrogenation catalyst, and react under the adiponitrile hydrogenation reaction conditions. The resulting reaction effluent enters the high-pressure separator 7 through pipeline 6, and the hydrogen-rich gas obtained by separation enters the circulating hydrogen compressor 22 through pipeline 8, and is sent to the inlet of the mixer 3 through pipeline 23 after being pressurized; the first liquid material separated by the high-pressure separator 7 enters the low-pressure separator 10 through pipeline 9 for further gas-liquid separation, and the obtained low-pressure gas is extracted through pipeline 11, and the second liquid material obtained by separation enters the deethanol tower 13 through pipeline 12, and ethanol is obtained at the top of the deethanol tower 13, which is sent to the inlet of the mixer 3 for recycling as an ethanol solvent through pipeline 14, and the bottom material of the deethanol tower 13 enters the first deweighting tower 16 through pipeline 15. The top material of the first de-weighting tower 16 mainly includes cyclohexylimide and hexamethylenediamine, and enters the product distillation tower 19 through pipeline 17. The cyclohexylimide product is extracted from the top of the product distillation tower 19 through pipeline 20, and the hexamethylenediamine product is extracted from the bottom of the tower through pipeline 21. The bottom material of the first de-weighting tower 16 enters the second de-weighting tower 24 through pipeline 18 for separation. The top material of the second de-weighting tower 24 includes hexamethylenediamine, aminocapronitrile and adiponitrile, which are sent to the inlet of the mixer 3 as circulating materials through pipeline 25. The bottom material is a high boiling point product and is directly discharged from the system through pipeline 26. DETAILED DESCRIPTION

[0050] The following examples will further illustrate the present invention, but should not be construed as limiting the present invention.

[0051] In the present invention,

[0052] ADN means "adiponitrile";

[0053] HMD refers to "hexamethylenediamine";

[0054] ACN refers to "6-aminocapronitrile", also known as "aminocapronitrile";

[0055] HMI refers to "hexamethyleneimine", also known as "cyclohexylimine";

[0056] DCH refers to "1,2-diaminocyclohexane";

[0057] AMCPA stands for "aminomethylcyclopentylamine".

[0058] The heavy component is mainly dihexylenetriamine.

[0059] In the embodiments and comparative examples, the calculation formulas for conversion and selectivity are as follows:

[0060] Reactant conversion rate = (1-mass of adiponitrile remaining after reaction / mass of adiponitrile before reaction) × 100%;

[0061] Product selectivity = mass of adiponitrile required to generate product / mass of adiponitrile consumed in the reaction × 100%.

[0062] In the examples and comparative examples, the products were analyzed using a gas chromatograph (Agilent 7890A) to analyze the components of each substance in the product. The lower limit of the chromatographic analysis was calculated to be 10 ppm based on the chromatographic signal-to-noise ratio.

[0063] In the following examples and comparative examples, the adiponitrile hydrogenation catalysts used are catalyst A and catalyst B, respectively.

[0064] The preparation method of catalyst A is:

[0065] (1) 14.28 g of magnesium nitrate hexahydrate, 77.86 g of nickel nitrate hexahydrate, and 11.33 g of cerium nitrate hexahydrate were mixed with 500 mL of deionized water and stirred at 40° C. for 1 h;

[0066] (2) Add a sufficient amount of oxalic acid-anhydrous ethanol solution, and after precipitation aging for 2 hours, use deionized water to filter and wash to obtain a precipitate. The obtained precipitate is dried at 90°C for 12 hours, and the dried product is calcined at 350°C for 2 hours. After granulation, a 14-20 mesh spherical catalyst A is obtained. Based on the dry weight of catalyst A and the mass of metal oxides, the NiO content is 74.8wt%, the MgO content is 8.4wt%, and the CeO content is 1.3wt%. 2 The content is 16.8wt%.

[0067] The preparation method of catalyst B is:

[0068] (1) 5.41 g of barium nitrate hexahydrate, 77.86 g of nickel nitrate hexahydrate, and 11.33 g of cerium nitrate hexahydrate were mixed with 500 mL of deionized water and stirred at 40° C. for 1 h;

[0069] (2) Add a sufficient amount of oxalic acid-anhydrous ethanol solution, and after precipitation aging for 2 hours, use deionized water to filter and wash to obtain a precipitate. The obtained precipitate is dried at 90°C for 12 hours, and the dried product is calcined at 350°C for 2 hours. After granulation, a 14-20 mesh spherical catalyst B is obtained. Based on the dry weight of the adiponitrile hydrogenation catalyst and the mass of the metal oxide, the NiO content is 74.8wt%, the MgO content is 8.4wt%, and the CeO content is 1.3wt%. 2 The content is 16.8wt%.

[0070] Example 1

[0071] After mixing 14-20 mesh spherical particle catalyst A with inert ceramic balls, the mixed volume ratio is catalyst: inert ceramic balls = 1:1, and loaded into a shell-and-tube reactor (the shell-and-tube length is 790 mm, and the inner diameter of a single shell-and-tube is 20 mm). The cooling medium of the shell side of the shell-and-tube reactor is water.

[0072] Activation treatment process: Reducing gas is introduced into the tube side of the tubular reactor. The reducing gas is a mixture of hydrogen and nitrogen, and the volume percentage of hydrogen in the reducing gas is 10%. The activation treatment conditions are: pressure 2.0MPa, temperature 400℃, gas hourly volume space velocity of reducing gas is 4000h -1 , reduction activation for 24h.

[0073] Reaction process: The reaction liquid raw material is adiponitrile / ethanol solution (adiponitrile concentration 50% by weight, fresh raw material mixed with recycled ethanol), new hydrogen and recycled hydrogen are mixed to form gaseous feed, the reaction liquid raw material and gaseous feed are mixed evenly in the mixer, preheated to 75.0°C and enter the tube side of the tubular reactor, and contact with the reduced activated catalyst A for reaction. The reaction conditions are: hydrogen partial pressure of 4.0MPa, average tube side temperature of 80.0°C, hydrogen nitrile molar ratio of 100, adiponitrile liquid mass space velocity of 1.0h -1 .

[0074] The reaction effluent enters the high-pressure separator, the first liquid material at the bottom of the high-pressure separator enters the low-pressure separator, and the first gaseous material at the top is mixed with new hydrogen and enters the mixer. The gas at the top of the low-pressure separator is discharged from the system in the form of purge gas, and the second liquid material obtained by the low-pressure separator enters the deethanol tower.

[0075] The top pressure of the deethanol tower is 50KPa (absolute pressure), the top temperature is 61.4°C, the theoretical plate number is 15, the reflux ratio is 1.2, the top ethanol concentration is 100.00%, and the bottom material composition (mass fraction, the same below) is 2.48% adiponitrile, 16.28% cyclohexylimide, 0.48% aminocapronitrile, 79.55% hexamethylenediamine, and 1.21% heavy components. The top material is mixed with fresh raw materials and then circulated, and the bottom material enters the first deweighting tower.

[0076] The top pressure of the first deweighting tower is 10KPa (absolute pressure), the top temperature is 103.0°C, the theoretical plate number is 20, the reflux ratio is 2.9, the top material composition is 16.99% cyclohexylimide, 83.01% hexamethylenediamine, the bottom material composition is 59.41% adiponitrile, 11.54% aminocapronitrile, 0.19% hexamethylenediamine, and 28.86% heavy components. The top material enters the product distillation tower, and the bottom material is directly discharged from the system.

[0077] The top pressure of the product distillation tower is 50 KPa (absolute pressure), the top temperature is 114.3°C, the theoretical plate number is 25, the reflux ratio is 2.2, and the cycloheximide product produced from the top of the tower has a concentration of 99.99%, an ethanol concentration of 0.01%, and other impurities less than 10 ppm. The bottom material composition is 100.00% hexamethylenediamine, and other impurities are less than 1 ppm.

[0078] Other analysis results and calculation results are shown in Table 1. The total selectivity of the target product in Table 1 refers to the sum of the selectivity of hexamethylenediamine and the selectivity of cycloheximide.

[0079] Example 2

[0080] The same technical scheme as in Example 1 was used for the reaction, except that the preheating temperature during the reaction was 90.0° C. and the average temperature of the tube was 95.0° C. The product analysis results and calculation results are shown in Table 1.

[0081] Example 3

[0082] The same technical scheme as in Example 1 was used for the reaction, except that the preheating temperature during the reaction was 105.0° C. and the average temperature of the tube was 110.0° C. The product analysis results and calculation results are shown in Table 1.

[0083] Example 4

[0084] After mixing 14-20 mesh spherical particle catalyst B with inert porcelain balls, the mixed volume ratio is catalyst: inert porcelain balls = 1:1, and loaded into a shell-and-tube reactor (the shell-and-tube length is 790 mm, and the inner diameter of a single shell-and-tube is 20 mm). The cooling medium of the shell side of the shell-and-tube reactor is water.

[0085] Activation treatment process: Reducing gas is introduced into the tube side of the tubular reactor. The reducing gas is a mixture of hydrogen and nitrogen, and the volume percentage of hydrogen in the reducing gas is 10%. The activation treatment conditions are: pressure 2.0MPa, temperature 400℃, gas hourly volume space velocity of reducing gas is 4000h -1 , reduction activation for 24h.

[0086] Reaction process: The reaction raw material is adiponitrile / ethanol solution (adiponitrile concentration 50wt%), new hydrogen and circulating hydrogen are mixed to form gaseous feed, the reaction raw material and gaseous feed are mixed and preheated to 75.0℃ and enter the tube side of the tubular reactor, and contact with the reduced activated catalyst B for reaction. The reaction conditions are: hydrogen partial pressure of 4.0MPa, average tube side temperature of 80.0℃, hydrogen nitrile molar ratio of 100, adiponitrile liquid mass space velocity of 1.0h -1 .

[0087] The reaction effluent enters the high-pressure separator, the first liquid material at the bottom of the high-pressure separator enters the low-pressure separator, and the first gaseous material at the top is mixed with new hydrogen and enters the mixer. The gas at the top of the low-pressure separator is discharged from the system in the form of purge gas, and the second liquid material obtained by the low-pressure separator enters the deethanol tower.

[0088] The top pressure of the deethanol tower is 50 KPa (absolute pressure), the top temperature is 61.4°C, the theoretical plate number is 15, the reflux ratio is 1.3, the ethanol concentration produced from the top is 100.00%, and the composition of the bottom material (mass fraction, the same below) is 3.08% adiponitrile, 19.03% cycloheximide, 1.06% aminocapronitrile, 76.31% hexamethylenediamine, and 0.52% heavy components.

[0089] The top pressure of the first deweighting tower is 10 KPa (absolute pressure), the top temperature is 98.6°C, the theoretical plate number is 20, the reflux ratio is 0.7, the top material composition is 21.69% cyclohexylimide, 78.31% hexamethylenediamine, the bottom material composition is 25.07% adiponitrile, 8.65% aminocapronitrile, 62.07% hexamethylenediamine, and 4.21% heavy components.

[0090] The top pressure of the product distillation tower is 50 KPa (absolute pressure), the top temperature is 114.3°C, the theoretical plate number is 25, the reflux ratio is 2.0, and the cycloheximide product produced from the top of the tower has a concentration of 99.99%, an ethanol concentration of 0.01%, and other impurities less than 10 ppm. The bottom material composition is 100.00% hexamethylenediamine, and other impurities are less than 1 ppm.

[0091] The top pressure of the second deweighting tower is 3KPa (absolute pressure), the top temperature is 97.7°C, the theoretical plate number is 15, the reflux ratio is 0.8, the top material composition is 12.23% aminocapronitrile, 87.77% hexamethylenediamine, the top material is mixed with the fresh liquid phase material and enters the mixer together; the bottom material composition is 85.60% adiponitrile, 14.40% heavy components, and is directly discharged. Other analysis results and calculation results are shown in Table 1.

[0092] Comparative Example 1

[0093] The same technical scheme as in Example 1 was used for the reaction, except that the preheating temperature during the reaction was 55.0° C. and the average temperature of the tube was 60.0° C. The product analysis results and calculation results are shown in Table 1.

[0094] Comparative Example 2

[0095] The same technical scheme as in Example 1 was used for the reaction, except that the preheating temperature during the reaction was 125.0° C. and the average temperature of the tube was 130.0° C. The product analysis results and calculation results are shown in Table 1.

[0096] Comparative Example 3

[0097] The process was carried out in accordance with the same technical scheme as in Example 1, except that there was no cooling medium heat exchange during the reaction, and the material temperature at the tube outlet reached 137.0° C. The product analysis results and calculation results are shown in Table 1.

[0098] Comparative Example 4

[0099] The process was carried out in accordance with the same technical scheme as in Example 3, except that there was no cooling medium heat exchange during the reaction, and the material temperature at the tube outlet reached 165.8° C. The product analysis results and calculation results are shown in Table 1.

[0100] Table 1

[0101]

Claims

1. A method for synthesizing hexamethylenediamine and co-producing cycloheximide, comprising: (1) an adiponitrile raw material, an ethanol solvent, and hydrogen enter a mixer together to obtain a uniformly mixed gas-liquid mixture, wherein the mass concentration of adiponitrile in the mixture of the adiponitrile raw material and the ethanol solvent is 10 to 99%; (2) the gas-liquid mixture enters the tube side of the shell-and-tube reactor, contacts with the activated adiponitrile hydrogenation catalyst, and reacts under adiponitrile hydrogenation reaction conditions, and a cooling medium is used in the shell side of the shell-and-tube reactor to control the reaction temperature in the tube side within a certain range; The reaction conditions for adiponitrile hydrogenation are: reaction temperature of 65-125°C, hydrogen partial pressure of 2-10 MPa, liquid hourly mass space velocity of adiponitrile of 0.1-10 h -1 , the molar ratio of hydrogen to adiponitrile is 50 to 500; The adiponitrile hydrogenation catalyst comprises an active component of nickel, an additive 1 and an additive 2, wherein the content of nickel is 25 to 90% by weight, the content of the additive 1 is 0.1 to 30% by weight, and the content of the additive 2 is 5 to 50% by weight, based on the dry weight of the catalyst, and calculated as oxide, wherein the additive 1 is selected from at least one of the metal elements of the IIA group, and the additive 2 is selected from at least one of the lanthanide metal elements; (3) The reaction effluent obtained in step (2) enters a high-pressure separator to separate a hydrogen-rich gas and a first liquid material. The first liquid material enters a low-pressure separator for further gas-liquid separation to obtain a second liquid material. The second liquid material enters a deethanolation tower, a first deweighting tower, and a product distillation tower in sequence to separate a cycloheximide product and a hexamethylenediamine product.

2. The method according to claim 1, characterized in that In the mixture of adiponitrile raw material and ethanol solvent, the mass concentration of adiponitrile is 30-70%; In step (3), the ethanol obtained from the deethanol tower is recycled as an ethanol solvent.

3. The method according to claim 1, characterized in that In the shell-and-tube reactor, the aspect ratio of a single shell-and-tube is in the range of 10 to 200, and the diameter of a single shell-and-tube is in the range of 10 to 100 mm.

4. The method according to claim 1, characterized in that: The adiponitrile hydrogenation catalyst has a shape selected from one or more of spherical, annular, cylindrical, butterfly and clover-shaped; The loading ratio of the adiponitrile hydrogenation catalyst is 0.5 to 1.2 kg / L.

5. The method according to claim 1, characterized in that The cooling medium is at least one of molten salt, heat transfer oil and water.

6. The method according to claim 1, characterized in that The adiponitrile hydrogenation catalyst is activated in a reducing gas atmosphere to obtain an activated adiponitrile hydrogenation catalyst. The activation treatment conditions are: pressure 0.5-8.0 MPa, temperature 120-450° C., and gas hourly volume space velocity of the reducing gas of 200-20000 h -1 The activation treatment time is 12 to 120 hours, and the reducing gas contains hydrogen and an optional protective gas, wherein the protective gas is nitrogen and / or water vapor.

7. The method according to claim 1, characterized in that In the adiponitrile hydrogenation catalyst, based on the dry weight of the catalyst and calculated as oxide, the content of nickel is 40-85 weight %, the content of the auxiliary agent 1 is 4-25 weight %, and the content of the auxiliary agent 2 is 10-45 weight %.

8. The method according to claim 1 or 7, characterized in that: The auxiliary agent 1 is selected from one or more of magnesium, calcium and barium, and the auxiliary agent 2 is selected from lanthanum and / or cerium.

9. The method according to claim 1 or 7, characterized in that: The adiponitrile hydrogenation catalyst is prepared by a coprecipitation method.

10. The method according to claim 9, characterized in that A mixed solution of a nickel precursor, a precursor of an auxiliary agent 1 and a precursor of an auxiliary agent 2 is mixed with a precipitant for precipitation and aging. The obtained precipitate is washed, dried, calcined and granulated to obtain an adiponitrile hydrogenation catalyst.

11. The method according to claim 1, characterized in that: In step (3), the second liquid material enters the deethanol tower, ethanol is extracted from the top of the deethanol tower, the bottom material of the deethanol tower enters the first deweighting tower, the top material of the first deweighting tower enters the product distillation tower, the cycloheximide product is extracted from the top of the product distillation tower, and the hexamethylenediamine product is extracted from the bottom of the tower.

12. The method according to claim 1 or 11, characterized in that: In step (3), the number of theoretical plates of the ethanol removal tower is 12 to 25; the number of theoretical plates of the first deweighting tower is 15 to 30; and the number of theoretical plates of the product distillation tower is 16 to 25; The operating conditions of the deethanol tower are: the tower top pressure is 50-101KPa absolute pressure, the tower top temperature is 60-80°C, and the reflux ratio is 0.2-20; The operating conditions of the first deweighting tower are: the tower top pressure is 10-50KPa absolute pressure, the tower top temperature is 100-150°C, and the reflux ratio is 0.3-30; The operating conditions of the product distillation tower are: top pressure 5-50KPa absolute pressure, top temperature 55-115°C, and reflux ratio 1-20.

13. The method according to claim 1 or 11, characterized in that: In step (3), a second deweighting tower is included. The bottom material of the first deweighting tower enters the second deweighting tower for separation. The top material of the second deweighting tower is circulated to the mixer inlet as a circulating material. The bottom material is a high boiling point product and is directly discharged from the device.

14. The method according to claim 1, characterized in that The number of theoretical plates of the second deweighting tower is 10 to 25; The operating conditions of the second deweighting tower are: tower top pressure 0.5-3KPa absolute pressure, tower top temperature 75-100°C, and reflux ratio 0.05-10.

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