A method for synthesizing hexamethylenediamine from caprolactam

Abstract

The present disclosure relates to a method for synthesizing hexamethylenediamine from caprolactam, comprising the following steps: (1) contacting caprolactam, hydrogen, and a hydrogenation catalyst under catalytic hydrogenation conditions to carry out a catalytic hydrogenation reaction to obtain a first product comprising hexamethyleneimine; and (2) contacting the first product, ammonia, and an amination catalyst under catalytic amination conditions to carry out a catalytic amination reaction to obtain a second product comprising hexamethylenediamine. This method can improve catalytic activity and product yield.

Description

Technical Field

[0001] The present disclosure relates to the technical field of hexamethylenediamine preparation, and in particular, to a method for synthesizing hexamethylenediamine from caprolactam. Background Art

[0002] Hexamethylenediamine is an important chemical raw material commonly used to synthesize important industrial products such as nylon 66, nylon 610, and HDI. Industrial hexamethylenediamine is exclusively produced by the hydrogenation of adiponitrile. my country lacks production facilities for adiponitrile, the raw material for the synthesis of hexamethylenediamine, and relies entirely on imports for its needs.

[0003] Another process route uses caprolactam as a raw material to synthesize hexamethylenediamine. However, there are relatively few reports on this technology, with the earliest reports being US Patents 2,234,566 and 2,181,140. US Patent 2,234,566 reports the synthesis of 6-aminocapronitrile from caprolactam at a reaction temperature of 360°C and an ammonia / caprolactam molar ratio of 6 using silica gel-supported copper as a dehydration catalyst. Unreacted caprolactam is separated by distillation, and the aminocapronitrile is subsequently catalytically hydrogenated over a nickel or cobalt catalyst to synthesize hexamethylenediamine. The caprolactam conversion rate is 21.7%, and the 6-aminocapronitrile yield is 25%. The yield of hexamethylenediamine is not disclosed in the patent. US Patent 3,855,267 reports the passage of a mixture of ammonia and caprolactam over an aluminum phosphate catalyst. Under an ammonia / caprolactam molar ratio of 75 to 100, the selectivity for 6-aminocapronitrile is 87%. Both of these methods for preparing 6-aminocapronitrile suffer from low catalyst activity and high energy consumption. Chinese invention patent CN107739318A reports a method and apparatus for preparing 6-aminocapronitrile from caprolactam using a liquid-phase process. This method uses phosphoric acid or a phosphate as a catalyst, and while the reaction temperature is around 280°C, the yield is low, with an analysis of the yield in examples showing only about 50%. This method suffers from drawbacks such as complex separation of the catalyst and solvent, high energy consumption, and low caprolactam conversion. The method for synthesizing 6-aminocapronitrile from caprolactam reported in Chinese invention patent CN107602416A is similar to the method reported in US Pat. However, the reported method for preparing 6-aminocapronitrile from caprolactam using a vapor-phase process has a reaction temperature of around 350°C, and the contact time between caprolactam and ammonia is less than 1 second, making the process difficult to control.

[0004] In addition to producing 6-aminocapronitrile through ammoniating dehydration, caprolactam can also produce hexamethyleneimine under the action of a hydrogenation catalyst. However, since caprolactam is very easy to polymerize, the reaction conversion rate is low. In addition, existing metal catalysts also have problems such as short lifespan and low selectivity. Summary of the Invention

[0005] The purpose of the present disclosure is to provide a method for synthesizing hexamethylenediamine from caprolactam, which can improve the raw material conversion rate, target product selectivity and reaction stability.

[0006] In order to achieve the above object, the present disclosure provides a method for synthesizing hexamethylenediamine from caprolactam, the method comprising the following steps:

[0007] (1) contacting caprolactam, hydrogen, and a hydrogenation catalyst under catalytic hydrogenation conditions to perform a catalytic hydrogenation reaction to obtain a first product containing hexamethyleneimine;

[0008] (2) Under catalytic amination conditions, the first product, ammonia gas and an amination catalyst are contacted to perform a catalytic amination reaction to obtain a second product containing hexamethylenediamine.

[0009] Optionally, in step (1), the catalytic hydrogenation conditions include: reaction temperature of 100-400°C, reaction pressure of 0.1-20 MPa, molar ratio of hydrogen to caprolactam of 1-1000:1, weight hourly space velocity of liquid feed of 0.1-10h -1 Preferably, the catalytic hydrogenation conditions include: reaction temperature of 200-350°C, reaction pressure of 0.5-10 MPa, molar ratio of hydrogen to caprolactam of 1-50:1, weight hourly space velocity of liquid feed of 0.4-5h -1 .

[0010] Optionally, in step (1), the hydrogenation catalyst is selected from one or more of a copper-based hydrogenation catalyst, a palladium-based hydrogenation catalyst, a ruthenium-based hydrogenation catalyst and a platinum-based hydrogenation catalyst; preferably a copper-based hydrogenation catalyst; further preferably, based on the total weight of the copper-based hydrogenation catalyst, the copper-based catalyst comprises 10 to 50 weight % CuO, 5 to 40 weight % ZnO, 20 to 80 weight % Al2O3 and 0 to 20 weight % La2O3.

[0011] Optionally, in step (2), the amination reaction is carried out in a continuous reaction, preferably in a fixed bed reactor; the catalytic amination conditions include: a reaction temperature of 120-700° C., a weight ratio of ammonia to hexamethyleneimine of (0.1-100):1, an ammonia partial pressure of 0.1-5.0 MPa, and a weight hourly space velocity of hexamethyleneimine of 1-100 h -1 Preferably, the catalytic amination conditions include: a reaction temperature of 200-400°C, a weight ratio of ammonia to hexamethyleneimine of (1-50):1, an ammonia partial pressure of 0.2-3.0 MPa, and a weight hourly space velocity of hexamethyleneimine of 0.5-20 h -1 .

[0012] Optionally, the method further comprises: before step (2), performing a first separation and purification treatment on the first product to obtain a material rich in hexamethyleneimine; then subjecting the material rich in hexamethyleneimine to the catalytic amination reaction; and after step (2), performing a second separation and purification treatment on the second product.

[0013] Optionally, the amination catalyst includes a first amination catalyst; the first amination catalyst includes an inorganic carrier and a supporting component; the inorganic carrier is selected from one or more of alumina, titanium dioxide, silicon dioxide and molecular sieves; the supporting component is selected from one or more of vanadium oxide, phosphorus oxide and molybdenum oxide; preferably, based on the total weight of the first amination catalyst, the first amination catalyst includes 5 to 95 weight% of the inorganic carrier and 2 to 50 weight% of the supporting component.

[0014] Optionally, the amination catalyst includes a second amination catalyst; on a dry basis and based on the total weight of the second amination catalyst, the second amination catalyst includes 5 to 98 weight% of a titanium-containing support, 2 to 30 weight% of vanadium oxide, 0 to 30 weight% of a metal M oxide and / or 0 to 10 weight% of an inorganic oxide; wherein the titanium-containing support includes TiO2 and a titanium-containing molecular sieve, the M is selected from one or more of VB elements, VIB elements, Group VIII elements and lanthanum elements, and the inorganic oxide includes one or both of Al2O3 and SiO2; preferably, on a dry basis and based on the total weight of the second amination catalyst, the second amination catalyst includes 20 to 95 weight% of a titanium-containing support, 3 to 20 weight% of vanadium oxide, 0.5 to 10 weight% of a metal M oxide and / or 0.2 to 6 weight% of an inorganic oxide.

[0015] Optionally, on a dry basis, the weight ratio of TiO2 and the titanium-containing molecular sieve in the titanium-containing carrier is 1:(0.001-5), preferably 1:(0.05-2); the titanium-containing molecular sieve includes a titanium silicon molecular sieve; the titanium silicon molecular sieve is selected from one or more of HTS molecular sieve, TS-1 molecular sieve, TS-2 molecular sieve and TS-48 molecular sieve; optionally, the metal M is selected from one or more of tungsten, molybdenum, chromium, zinc, manganese, lanthanum and iron, preferably one or more of tungsten, molybdenum and chromium, and further preferably one or two of molybdenum and tungsten.

[0016] Optionally, the BET specific surface area of ​​the second amination catalyst is 10 to 300 m 2 / g, the total pore volume is 0.02-0.4 mL / g, and the micropore volume is 0.01-0.1 mL / g; optionally, the shape of the second amination catalyst is selected from one or more of sphere, strip, cylinder, ring, clover, four-leaf, honeycomb and butterfly.

[0017] Optionally, in step (2), the second amination catalyst is prepared by a preparation method comprising the following steps: S1, contacting a vanadium source, water and an acid to carry out an oxidation reaction; adding a metal M source and a titanium-containing carrier to the oxidation reaction product to obtain a mixture; performing a first drying treatment on the mixture to obtain an intermediate solid product; S2, sequentially performing a molding treatment, a second drying treatment and a calcination treatment on the intermediate solid product.

[0018] Optionally, in step S1, the weight ratio of water: vanadium source: acid: metal M source: titanium-containing carrier is (0.5-2.0): (0.05-0.2): (0.05-0.5): (0-0.5): 1; preferably (0.8-1.6): (0.05-0.15): (0.1-0.3): (0.05-0.3): 1.

[0019] Optionally, in step S1, the vanadium source is selected from one or more of ammonium metavanadate, sodium metavanadate and vanadium pentoxide; the acid is selected from one or more of oxalic acid, citric acid and nitric acid; the metal M source is selected from one or more of nitrates, phosphates and chlorides of metal M elements; preferably, it is selected from one or more of ammonium molybdate tetrahydrate, sodium tungstate, chromium nitrate and lanthanum nitrate.

[0020] Optionally, step S1 includes: dissolving the vanadium source in water, then adding the acid to the vanadium source solution to carry out the oxidation reaction to obtain an oxidation reaction product; adding the metal M source to the oxidation reaction product, performing a first mixing to obtain a first mixture, optionally, the temperature of the first mixing is 50-100°C, and the time is 60-300 min; adding the titanium-containing carrier to the first mixture, performing a second mixing to obtain a second mixture, optionally, the temperature of the second mixing is 30-80°C, and the time is 30-300 min; subjecting the second mixture to the first drying treatment, and grinding the resulting product to obtain the intermediate solid product; optionally, the temperature of the first drying treatment is 80-150°C.

[0021] Optionally, the molding process in step S2 is extrusion molding; step S2 includes: extruding and mixing the intermediate solid product with the pore-expanding agent and the auxiliary agent, and then sequentially performing the molding process, the second drying process and the calcination process; or the molding process in step S2 is ball molding, and step S2 also includes: mixing the intermediate solid product with the inorganic oxide source, and then sequentially performing the molding process, the second drying process and the calcination process.

[0022] Optionally, in step S2, the amount of the pore enlarging agent added is 0.5 to 10 weight %, preferably 1 to 5 weight %, calculated on a dry basis and based on the added weight of the titanium-containing carrier; the amount of the extrusion aid added is 0.5 to 4 weight %, preferably 0.5 to 2 weight %; or the amount of the inorganic oxide precursor added is 0.1 to 5 weight %, preferably 0.1 to 2.0 weight %, calculated on a dry basis and based on the added weight of the titanium-containing carrier.

[0023] Optionally, in step S2, the pore expanding agent is selected from one or more of sesbania powder, paraffin, stearic acid, glycerol, starch, polyethylene glycol, polyvinyl alcohol, polyethylene oxide, polyacrylamine, cellulose methyl ether, cellulose, polymer alcohol and graphite; the extrusion aid is selected from one or more of organic acids, inorganic acids and inorganic bases, preferably, the extrusion aid is selected from one or more of oxalic acid, tartaric acid, citric acid, nitric acid, hydrochloric acid, acetic acid, formic acid, ammonia water, sodium hydroxide and potassium hydroxide; the inorganic oxide source is added in the form of an inorganic oxide or an inorganic oxide precursor; wherein the inorganic oxide includes one or both of Al2O3 and SiO2; the inorganic oxide precursor is selected from one or more of aluminum sol, silica sol and water glass.

[0024] Optionally, in step S2, the conditions for the second drying treatment include: temperature of 80-200°C, preferably 100-150°C; time of 1-10 hours, preferably 2-4 hours; the conditions for the calcination include: temperature of 200-900°C, preferably 500-800°C; time of 0.5-10 hours, preferably 2-4 hours.

[0025] Through the above technical solution, the present disclosure provides a method for synthesizing hexamethylenediamine from caprolactam. The method uses caprolactam as a raw material, obtains an intermediate product hexamethyleneimine through a hydrogenation reaction, and then performs a ring-opening amination reaction on the hexamethyleneimine to synthesize hexamethylenediamine. The reaction raw materials are easily available, the hydrogenation catalyst and the amination catalyst have high selectivity and activation activity for the target product, and the product yield of the synthesis process is high. In addition, the reaction process of this method is environmentally friendly.

[0026] Other features and advantages of the present disclosure will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0027] The following describes the specific embodiments of the present disclosure in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0028] The present disclosure provides a method for synthesizing hexamethylenediamine from caprolactam, the method comprising the following steps:

[0029] (1) contacting caprolactam, hydrogen, and a hydrogenation catalyst under catalytic hydrogenation conditions to perform a catalytic hydrogenation reaction to obtain a first product containing hexamethyleneimine;

[0030] (2) Under catalytic amination conditions, the first product, ammonia gas and an amination catalyst are contacted to perform a catalytic amination reaction to obtain a second product containing hexamethylenediamine.

[0031] The present disclosure provides a method for synthesizing hexamethylenediamine from caprolactam. The method uses caprolactam as a raw material, obtains an intermediate product hexamethyleneimine through a hydrogenation reaction, and then performs a ring-opening amination reaction on the hexamethyleneimine to synthesize hexamethylenediamine. The reaction raw materials are readily available, the hydrogenation catalyst and the amination catalyst both have high selectivity and activation activity for the target product, and the product yield of the synthesis process is high. In addition, the reaction process of the method is environmentally friendly.

[0032] In a specific embodiment, caprolactam is used as a raw material, which is heated and melted, and then contacted with hydrogen in a reactor to carry out a hydrogenation reaction.

[0033] In one embodiment, in step (1), the catalytic hydrogenation conditions include: a reaction temperature of 100 to 400°C, a reaction pressure of 0.1 to 20 MPa, a molar ratio of hydrogen to caprolactam of 1 to 1000:1, a weight hourly space velocity of the liquid feed of 0.1 to 10 h -1 .

[0034] In a preferred embodiment, the catalytic hydrogenation conditions include: reaction temperature of 200-350°C, reaction pressure of 0.5-10 MPa, molar ratio of hydrogen to caprolactam of 1-50:1, weight hourly space velocity of liquid feed of 0.4-5h -1 In the present disclosure, the liquid feed weight hourly space velocity refers to the weight hourly space velocity when molten caprolactam is used as a raw material.

[0035] According to the present disclosure, in the catalytic hydrogenation reaction of step (1), the hydrogenation catalyst used can be a catalyst conventionally used in the art.

[0036] In a specific embodiment, in step (1), the hydrogenation catalyst is selected from one or more of a copper-based hydrogenation catalyst, a palladium-based hydrogenation catalyst, a ruthenium-based hydrogenation catalyst and a platinum-based hydrogenation catalyst; preferably a copper-based hydrogenation catalyst; further preferably, based on the total weight of the copper-based hydrogenation catalyst, the copper-based catalyst comprises 10 to 50 weight % CuO, 5 to 40 weight % ZnO, 20 to 80 weight % Al2O3 and 0 to 20 weight % La2O3.

[0037] In a specific embodiment, in step (1), the hydrogenation catalyst is obtained by a preparation method comprising the following steps: dissolving soluble salts of metal elements such as copper, zinc, aluminum and lanthanum in deionized water, and dripping sodium carbonate or ammonia solution as a precipitant therein under stirring until the pH value is 5 to 9. The obtained precipitate is filtered after aging, and the filter cake is washed with deionized water, dried and calcined to obtain a catalyst powder, and a certain amount of demolding agent is added, and the hydrogenation catalyst is obtained by tableting. The amount of soluble salts of metal elements added in the present disclosure can be adjusted according to the target composition of the hydrogenation catalyst; the preparation conditions of the hydrogenation catalyst can also adopt conventional parameters in the field, or be adjusted according to the performance requirements of the hydrogenation catalyst. Among them, in order to ensure the complete precipitation of metal ions, the precipitant sodium carbonate can be added at 1 to 1.1 times the total molar number of metal ions.

[0038] According to the present disclosure, the hydrogenation reaction is that caprolactam and hydrogen are contacted in a hydrogenation reactor under a catalyst and reaction conditions to generate hexamethyleneimine. The reaction can be a continuous reaction or a batch reaction. According to the present disclosure, the hydrogenation reaction of caprolactam and hydrogen in step (1) can be carried out in liquid phase or gas phase according to conventional hydrogenation reaction conditions. The batch reaction generally uses a reactor as a reactor, caprolactam and a hydrogenation catalyst are put into the reactor, hydrogen is introduced and the reaction is carried out at a certain temperature and pressure, and after the reaction is completed, the reaction product is unloaded from the reactor, the product is separated, and the next batch of materials is put into the reactor for reaction. The continuous hydrogenation reaction can use a shell and tube reactor, the hydrogenation catalyst is fixed in the tube, and cooling water is passed through the shell to remove the heat released by the reaction.

[0039] In one embodiment, in step (2), the amination reaction is carried out as a continuous reaction, preferably in a fixed bed reactor;

[0040] The catalytic amination conditions include: a reaction temperature of 120-700° C., a weight ratio of ammonia to hexamethyleneimine of 0.1-100:1, an ammonia partial pressure of 0.1-5.0 MPa, and a weight hourly space velocity of hexamethyleneimine of 1-100 h -1 .

[0041] In a preferred embodiment, the catalytic amination conditions include: reaction temperature of 200-400°C, a weight ratio of ammonia to hexamethyleneimine of 1-50:1, ammonia partial pressure of 0.2-3.0 MPa, and a hexamethyleneimine weight hourly space velocity of 0.5-20 h -1 The preferred amination reaction conditions provided by the present disclosure can achieve higher reaction activity and product yield.

[0042] In one embodiment, the amination catalyst includes a first amination catalyst; the first amination catalyst includes an inorganic support and a supporting component; the inorganic support is selected from one or more of alumina, titanium dioxide, silicon dioxide and molecular sieves; the molecular sieve can be a conventional molecular sieve in the art, such as one or more of HTS molecular sieve, TS-1, TS-2 and TS-48 molecular sieves;

[0043] The supported component is selected from one or more of vanadium oxide, phosphorus oxide and molybdenum oxide;

[0044] Preferably, based on the total weight of the first amination catalyst, the first amination catalyst comprises 5 to 95 wt% of an inorganic carrier and 2 to 50 wt% of a supporting component.

[0045] The first amination catalyst used in the present disclosure can be prepared by a preparation method known in the art.

[0046] In one embodiment, the first amination catalyst is prepared by a method comprising the following steps: impregnating TiO2 with one or more of vanadyl oxalate, a phosphorus source (phosphoric acid or a phosphate), and a molybdenum source (a soluble molybdenum salt solution), followed by drying and calcining. The amount of raw materials added is adjusted based on the target catalyst composition. The preparation conditions may also be conventional parameters in the art or adjusted based on catalyst performance requirements.

[0047] In another embodiment, the amination catalyst comprises a second amination catalyst;

[0048] On a dry basis and based on the total weight of the second amination catalyst, the second amination catalyst comprises 5 to 98 weight percent of a titanium-containing support, 2 to 30 weight percent of a vanadium oxide, 0 to 30 weight percent of a metal M oxide, and / or 0 to 10 weight percent of an inorganic oxide; wherein the titanium-containing support comprises TiO2 and a titanium-containing molecular sieve, the M is selected from one or more of VB elements, VIB elements, VIII group elements, and lanthanum elements, and the inorganic oxide comprises one or both of Al2O3 and SiO2.

[0049] The addition of an inorganic oxide to the second amination catalyst used in the present disclosure can improve the catalyst strength, thereby increasing the catalyst service life; the addition of a metal M oxide to the second amination catalyst can improve the conversion rate and target product selectivity of the catalyst during the amination of hexamethyleneimine to prepare hexamethylenediamine, thereby reducing the formation of by-products.

[0050] In the present disclosure, the content of each component in the catalyst is determined by X-ray fluorescence spectrometry. The content of the titanium-containing support in the second amination catalyst is calculated based on the total Ti element oxides obtained by XRF testing.

[0051] In a preferred embodiment, in step (2), the second amination catalyst comprises, on a dry basis and based on the total weight of the second amination catalyst, 20-95 wt % of a titanium-containing support, 3-20 wt % of a vanadium oxide, 0.5-10 wt % of a metal M oxide, and / or 0.2-6 wt % of an inorganic oxide. When the content of each component of the amination catalyst meets the ranges in this embodiment, the conversion rate and target product selectivity of the amination catalyst in the amination of hexamethyleneimine to produce hexamethylenediamine can be further improved. In the present disclosure, the content of each component in the amination catalyst is determined using an X-ray fluorescence spectrometer.

[0052] In one embodiment, in step (2), the weight ratio of TiO2 to the titanium-containing molecular sieve in the titanium-containing support is 1:(0.001-5), preferably 1:(0.05-2), calculated on a dry basis. The weight ratio of TiO2 to the titanium-containing molecular sieve in the present disclosure is calculated based on the mass ratio of the two raw materials added during the preparation process.

[0053] According to the present disclosure, TiO2 is well known to those skilled in the art, and when used as a carrier of a catalytic material, rutile and anatase titanium dioxide can be used, preferably rutile.

[0054] According to the present disclosure, titanium-containing molecular sieves are well known to those skilled in the art, including titanium silicate molecular sieves; the titanium silicate molecular sieve is selected from one or more of HTS molecular sieves, TS-1, TS-2 and TS-48 molecular sieves.

[0055] In one embodiment, the metal M is selected from one or more of tungsten, molybdenum, chromium, zinc, manganese, lanthanum and iron; preferably, it is selected from one or more of tungsten, molybdenum and chromium, and more preferably, it is selected from one or both of molybdenum and tungsten.

[0056] In one embodiment, in step (2), the BET specific surface area of ​​the second amination catalyst is 10-200 m 2 / g, preferably 20-150m 2 / g; the total pore volume is 0.02-0.3 mL / g, preferably 0.05-0.2 mL / g; the micropore volume is 0.01-0.1 mL / g, preferably 0.05-0.1 mL / g.

[0057] In one embodiment, the second amination catalyst is a granular shaped catalyst, and the shape of the amination catalyst is selected from one or more of spheres, bars, cylinders, rings, cloverleafs, quadrilobes, honeycombs, and butterfly shapes. Preferably, the catalyst is in the form of bars or pellets with a diameter of 0.5-5.0 mm.

[0058] In a preferred embodiment, in step (2), the second amination catalyst is prepared by a preparation method comprising the following steps:

[0059] S1, contacting a vanadium source, water and an acid to perform an oxidation reaction; adding a metal M source and a titanium-containing support to the oxidation reaction product to obtain a mixture; performing a first drying treatment on the mixture to obtain an intermediate solid product;

[0060] S2. The intermediate solid product is subjected to a molding process, a second drying process and a calcination process in sequence.

[0061] The present invention first performs an oxidation reaction on a vanadium source and an acid to obtain an oxidation product (for example, the vanadium source and oxalic acid are oxidized to obtain vanadium oxalate), and then the oxidation product is mixed with a metal M source and a titanium-containing carrier, and dried to remove moisture, so that the vanadium oxalate and the metal M source can be loaded on the titanium-containing carrier to obtain an intermediate solid product.

[0062] In one embodiment, in step S1, the weight ratio of water: vanadium source: acid: metal M source: titanium-containing carrier is (0.5-2.0): (0.05-0.2): (0.05-0.5): (0-0.5): 1.

[0063] In a preferred embodiment, in step S1, the weight ratio of water: vanadium source: acid: metal M source: titanium-containing support is (0.8-1.6): (0.05-0.15): (0.1-0.3): (0.05-0.3): 1. The amination catalyst synthesized according to the preferred addition ratio of the raw materials in this embodiment has higher catalytic activity and target product selectivity.

[0064] In one embodiment, in step S1, the vanadium source is selected from one or more of ammonium metavanadate, sodium metavanadate and vanadium pentoxide;

[0065] The acid is selected from one or more of oxalic acid, citric acid and nitric acid;

[0066] The metal M source is selected from one or more of nitrates, phosphates and chlorides of the metal M element; preferably, one or more of ammonium molybdate tetrahydrate, sodium tungstate, chromium nitrate and lanthanum nitrate.

[0067] In a specific implementation, step S1 includes:

[0068] dissolving the vanadium source in water, then adding the acid to the vanadium source solution to carry out the oxidation reaction to obtain an oxidation reaction product;

[0069] Adding the metal M source to the oxidation reaction product and performing a first mixing to obtain a first mixture, wherein the temperature of the first mixing is 50 to 100° C. and the time is 60 to 300 minutes;

[0070] Adding the titanium-containing support to the first mixture and performing a second mixing to obtain a second mixture, wherein the temperature of the second mixing is 30 to 80° C. and the time is 30 to 300 minutes;

[0071] The second mixture is subjected to the first drying treatment, and the resulting product is ground to obtain the intermediate solid product; optionally, the temperature of the first drying treatment is 80 to 150° C. Optionally, the product can be ground to a particle size of 30 μm or less, where the particle size refers to the maximum particle size of the ground particles.

[0072] According to the present disclosure, in step S2, the molding process includes extrusion molding and ball molding.

[0073] In one embodiment, when extrusion molding is adopted, step S2 further comprises: extruding and mixing the intermediate solid product with a pore-enlarging agent and an auxiliary agent, and then sequentially performing the molding process, the second drying process, and the calcination process.

[0074] In a preferred embodiment, the amount of the pore expander added is 0.5-10 wt%, preferably 1-5 wt%, based on the dry basis and the added weight of the titanium-containing carrier; the amount of the extrusion aid added is 0.5-4 wt%, preferably 0.5-2 wt%.

[0075] In a specific embodiment, the pore-enlarging agent is selected from one or more of sesbania powder, paraffin, stearic acid, glycerol, starch, polyethylene glycol, polyvinyl alcohol, polyethylene oxide, polyacrylamine, cellulose methyl ether, cellulose, polyol and graphite;

[0076] The extrusion aid is selected from one or more of oxalic acid, tartaric acid, citric acid, nitric acid, hydrochloric acid, acetic acid, formic acid, aqueous ammonia, sodium hydroxide and potassium hydroxide. The present disclosure adds a pore-enlarging agent and an extrusion aid in step S2 to facilitate the molding process of the catalyst and increase the pores of the catalyst.

[0077] In another embodiment, when ball forming is adopted, step S2 further comprises: mixing the intermediate solid product with an inorganic oxide source, and then sequentially performing the forming process, the second drying process and the calcination process.

[0078] According to the present disclosure, the inorganic oxide is used as a binder to bond the titanium-containing support and the vanadium oxide and metal M oxide powder particles together during extrusion, thereby improving the strength and life of the catalyst.

[0079] In a preferred embodiment, the amount of the inorganic oxide source added is 0.1 to 5 weight percent, preferably 0.1 to 2 weight percent, on a dry basis and based on the added weight of the titanium-containing carrier. The present invention adds an appropriate amount of inorganic oxide source to avoid the phenomenon that insufficient addition of the inorganic oxide source makes it difficult to shape the catalyst, and even if it is barely shaped, it will break when leaving the molding machine; and to avoid the disadvantage that excessive addition of the inorganic oxide source causes the spherical product to become soft and sticky.

[0080] According to the present disclosure, the inorganic oxide in the catalyst can be added in the form of an inorganic oxide or in the form of an inorganic oxide precursor. In a specific embodiment, the inorganic oxide includes one or both of Al2O3 and SiO2; the inorganic oxide precursor is selected from one or more of aluminum sol, silica sol and water glass.

[0081] In the present disclosure, the inorganic oxide as an inert substance can withstand the corrosion of strong acid and strong base, so that the formed particles will not be crushed during the alkali solution extraction process.

[0082] In further embodiments, if silica sol is used as the binder, it can be either acidic or alkaline, commercially available, or prepared using any conventional technique. Other inorganic oxide precursors having a binding effect known to those skilled in the art can also be added during the preparation of the composite catalyst.

[0083] In one embodiment, in step S2, the conditions of the second drying treatment include: a temperature of 80 to 200° C., preferably 100 to 150° C.; a time of 1 to 10 hours, preferably 2 to 4 hours;

[0084] The calcination conditions include: a temperature of 200-900°C, preferably 500-800°C; and a time of 0.5-10 hours, preferably 2-4 hours. According to the present disclosure, drying and calcining after extrusion molding can improve the strength of the amination catalyst.

[0085] In one embodiment, in step (2), the catalytic amination reaction is carried out in a fixed bed reactor. In the present disclosure, a fixed bed reactor can be used to carry out a continuous reaction.

[0086] In another specific embodiment, in step (2), the amination and dehydration reaction is carried out in a reactor. In the present disclosure, a reactor is used as a reactor to carry out a batch reaction.

[0087] According to the present disclosure, in the amination catalytic reaction, a liquid phase or gas phase embodiment known in the art can be adopted.

[0088] In one embodiment, the method further comprises: before step (2), performing a first separation and purification treatment on the first product to obtain a hexamethyleneimine-rich product; and then subjecting the hexamethyleneimine-rich product to the catalytic amination reaction; preferably, the purity of the hexamethyleneimine in the first product is 50 to 90% by weight or more.

[0089] According to the present disclosure, a conventional distillation apparatus can be used to meet the requirements for the first separation and purification of the first product, and its operating parameters can be controlled by referring to similar process parameters.

[0090] In one embodiment, the method further comprises: after step (2), performing a second separation and purification treatment on the second product; preferably, the purity of hexamethylenediamine in the second product is 99.0 wt % or more.

[0091] According to the present disclosure, the method for performing a second separation and purification of the ring-opening amination reactant (second product) to obtain pure hexamethylenediamine is distillation separation; preferably, the obtained second product is subjected to vacuum distillation to purify pure hexamethylenediamine, wherein the operating conditions and process of the vacuum distillation are: the vacuum distillation tower bottom temperature is 150-160°C, the vacuum degree is 1-4 kPa, when the tower top temperature is 20-40°C, ammonia and water are evaporated, and when the vacuum distillation tower top temperature is 130-140°C, hexamethylenediamine is evaporated.

[0092] The following describes the specific embodiments of the present disclosure in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0093] In the following examples, unless otherwise specified, all reagents used are commercially available reagents.

[0094] In the following examples and comparative examples, unless otherwise specified, pressures are gauge pressures.

[0095] In the following examples and comparative examples, the BET specific surface area, total pore volume, and micropore volume of the catalysts were measured using a Micromeritics ASAP-2020 automatic adsorption apparatus. The specific surface area was calculated using the two-parameter BET equation, the pore distribution was calculated using the BJH method, and the micropore specific surface area and pore volume were calculated using the t method.

[0096] The contents of each component in the catalyst were determined by X-ray fluorescence spectrometer (XRF).

[0097] Preparation Example 1-1

[0098] This example is used to prepare an exemplary hydrogenation catalyst, which specifically includes the following steps:

[0099] Preparation of copper nitrate, zinc nitrate and aluminum nitrate solutions: Add 300 mL of deionized water to a 1 L beaker, start stirring, heat to 50-60 ° C, add 94.3 g of copper nitrate, 46.6 g of zinc nitrate and 294.3 g of aluminum nitrate to make a metal salt solution.

[0100] Preparation of sodium carbonate (Na2CO3) solution: Add 1200 mL of deionized water to a 2 L beaker, start stirring, heat to 50-60 ° C, add 202 g of anhydrous sodium carbonate solid, and prepare a sodium carbonate aqueous solution.

[0101] The sodium carbonate aqueous solution and the metal salt solution were added to a 5 L reactor for contact at 80°C for 4 hours. The solid was filtered and dried, then calcined in a muffle furnace at 500°C for 6 hours to obtain a calcined solid. The calcined solid was ground in a grinder to a particle size of less than 30 microns, and 3% by weight of graphite powder (based on the weight of the ground solid) was added. The catalyst was then pelletized to obtain a finished catalyst. The resulting catalyst product was designated JQ-1.

[0102] XRF analysis revealed that the composition of the hydrogenation catalyst JQ-1 was 40.0 wt% CuO, 20.0 wt% ZnO, and 40.0 wt% Al2O3.

[0103] Preparation Example 1-2

[0104] This example is used to prepare an exemplary hydrogenation catalyst, which specifically includes the following steps:

[0105] Preparation of copper nitrate and zinc nitrate solution: Add 200 mL of deionized water to a 1 L beaker, start stirring, heat to 50-60 ° C, add 94.3 g of copper nitrate and 46.6 g of zinc nitrate to make a metal salt solution.

[0106] Preparation of sodium carbonate (Na2CO3) solution: Add 500 mL of deionized water to a 1 L beaker, start stirring, heat to 50-60 ° C, add 78 g of anhydrous sodium carbonate solid to prepare a sodium carbonate aqueous solution.

[0107] The sodium carbonate aqueous solution and the metal salt solution were added to a 5L reactor for contact at a temperature of 80°C. After contact for 2 hours, 200 kg of 20 wt% water glass was added to the mixed slurry and mixed evenly to obtain a slurry. After contact for 2 hours, the solid was filtered to obtain a solid. The obtained solid was dried and then calcined in a muffle furnace at 500°C for 6 hours to obtain a calcined solid. The calcined solid was crushed by a grinder to a particle size of less than 30 microns, 3 wt% of graphite powder was added, and the catalyst was formed into a finished product.

[0108] The obtained catalyst product was recorded as JQ-2.

[0109] XRF analysis revealed that the composition of the hydrogenation catalyst JQ-2 was 40.0 wt% CuO, 20.0 wt% ZnO, and 40.0 wt% SiO2.

[0110] Preparation Examples 1-3

[0111] This example is used to prepare an exemplary hydrogenation catalyst, which specifically includes the following steps:

[0112] Preparation of copper nitrate, zinc nitrate, aluminum nitrate and lanthanum nitrate solutions: Add 300 mL of deionized water to a 1 L beaker, start stirring, heat to 50-60 ° C, add 94.3 g of copper nitrate, 34.9 g of zinc nitrate, 294.3 g of aluminum nitrate and 10 g of lanthanum nitrate to make a metal salt solution.

[0113] Preparation of sodium carbonate (Na2CO3) solution: Add 1200 mL of deionized water to a 2 L beaker, start stirring, heat to 50-60 ° C, add 196 g of anhydrous sodium carbonate solid to prepare a sodium carbonate aqueous solution.

[0114] The sodium carbonate aqueous solution and the metal salt solution were added to a 5L reactor for contact at a temperature of 80°C. After contact for 4 hours, a solid was obtained by filtration. The obtained solid was dried and then calcined in a muffle furnace at 500°C for 6 hours to obtain a calcined solid. The calcined solid was crushed by a grinder to a particle size of less than 30 microns, 3% by weight of graphite powder was added, and the catalyst was formed into sheets to obtain a finished product.

[0115] The obtained catalyst product was recorded as JQ-3.

[0116] XRF analysis revealed that the composition of the hydrogenation catalyst JQ-3 was 40.0 wt% CuO, 15.0 wt% ZnO, 5.0 wt% La2O3 and 40.0 wt% Al2O3.

[0117] Preparation Example 2-1

[0118] This embodiment is used to prepare an exemplary first amination catalyst, which specifically includes the following steps:

[0119] 21.3 g of vanadyl oxalate and 19.3 g of ammonium dihydrogen phosphate were added to 150 mL of deionized water, stirred and heated for 2.0 h, and then 120 g of pseudo-boehmite (produced by Changling Branch of Sinopec Catalyst Company, with w(Al2O3) of 68.1%) was added to the above solution and stirred until a gel was formed. The obtained gel was aged for 4 h, washed to neutrality, dried at 120°C for 4 h, and calcined at 550°C for 4 h to obtain the catalyst.

[0120] The obtained product is designated as A-1. XRF analysis revealed that the composition of the amination catalyst A-1 was 80.8 wt% Al2O3, 12.5 wt% V2O5, and 6.7 wt% P2O5.

[0121] Preparation Example 2-2

[0122] This embodiment is used to prepare an exemplary first amination catalyst, which specifically includes the following steps:

[0123] Add 21.3 g of vanadyl oxalate and 19.3 g of ammonium dihydrogen phosphate to 150 mL of deionized water, stir and heat for 2.0 h, then add 81 g of TiO2 (DuPont R900, anatase type) to the above solution and stir until a gel is formed. The resulting gel is aged for 4 h, washed to neutrality, dried at 120 ° C for 4 h, and calcined at 550 ° C for 4 h to obtain the catalyst.

[0124] The obtained product was designated A-2. XRF analysis revealed that the composition of the amination catalyst A-2 was 80.8 wt% TiO2, 12.5 wt% V2O5, and 6.7 wt% P2O5.

[0125] Preparation Example 2-3

[0126] This embodiment is used to prepare an exemplary first amination catalyst, which specifically includes the following steps:

[0127] 21.3 g of vanadyl oxalate and 19.3 g of ammonium dihydrogen phosphate were added to 150 mL of deionized water, stirred and heated for 2.0 h, and then 404 g of 20 wt % water glass (produced by Changling Branch of Sinopec Catalyst Company) was added to the above solution and stirred until a gel was formed. The obtained gel was aged for 4 h, washed to neutrality, dried at 120°C for 4 h, and calcined at 550°C for 4 h to obtain the catalyst.

[0128] The obtained product is designated A-3. XRF analysis revealed that the composition of the amination catalyst A-3 was 80.8 wt% SiO2, 12.5 wt% V2O5, and 6.7 wt% P2O5.

[0129] Preparation Example 3-1

[0130] This embodiment is used to prepare an exemplary second amination catalyst, which specifically includes the following steps:

[0131] Preparation of vanadyl oxalate: Dissolve 50 g of ammonium metavanadate in 600 g of water and heat in a water bath. Slowly add 115 g of oxalic acid crystals while stirring. Oxidation reaction is carried out at 80°C for 120 min until the color of the slurry changes from yellow to purple. Continue heating in a water bath for 30 min to prepare a vanadyl oxalate solution.

[0132] The solution was stirred at 70°C. 500g of TiO2 (DuPont R900) and 50g of titanium silicalite (HTS-3 molecular sieve, manufactured by Hunan Jianchang) were added to the solution under continuous stirring. Stirring and aging were continued for 4 hours. The resulting product was dried in an oven at 110°C for 4 hours to remove moisture. The dried material was then added to a grinder and ground for 30 minutes to obtain an intermediate solid product (maximum particle size less than 30 microns).

[0133] In the above steps, the weight ratio of water:vanadium source:acid:metal M source:titanium-containing carrier is 1.091:0.091:0.209:0:1.

[0134] To the intermediate solid product, 15 g of sesbania powder (purchased from Lankao Plant Gum Factory) and 20 g of a 20 wt% aqueous nitric acid solution (4 g of nitric acid) were further added and thoroughly mixed. On a dry basis and based on the total weight of the titanium-containing support, the amount of sesbania powder added was 2.7 wt% and the amount of nitric acid added was 0.73 wt%. The catalyst was then extruded into a strip having a diameter of 2.5 mm through an extruder, dried at 120 ° C for 4 h, and then calcined at 750 ° C for 8 h to obtain a second strip-shaped amination catalyst, designated as catalyst B-1.

[0135] After drying, the strength of the catalyst B-1 was measured using a strength tester and found to be 42 N / cm.

[0136] Catalyst B-1 consisted of 93.0 wt% TiO2, 6.6 wt% V2O5 and 0.4 wt% SiO2.

[0137] Preparation Example 3-2

[0138] This embodiment is used to prepare an exemplary second amination catalyst, which specifically includes the following steps:

[0139] Preparation of vanadyl oxalate: Dissolve 60 g of ammonium metavanadate in 700 g of water and heat in a water bath. Slowly add 130 g of oxalic acid crystals while stirring. Oxidation reaction is carried out at 80°C for 120 min until the color of the slurry changes from yellow to purple to prepare a vanadyl oxalate solution.

[0140] Then, 50 g of ammonium molybdate tetrahydrate was added, and the mixture was heated on a water bath for 30 minutes to prepare an aqueous solution containing vanadyl oxalate and ammonium molybdate.

[0141] The solution was stirred at 70°C. 500g of TiO2 (DuPont R900) and 50g of titanium silicalite (HTS, HTS-3 molecular sieve, manufactured by Hunan Jianchang) were added with continued stirring and aged for 4 hours. The resulting product was dried in an oven at 110°C for 4 hours to remove moisture. The dried material was then added to a grinder and ground for 30 minutes to obtain an intermediate solid product (maximum particle size less than 40 microns).

[0142] In the above steps, the weight ratio of water:vanadium source:acid:metal M source:titanium-containing carrier is 1.273:0.109:0.236:0.091:1.

[0143] Then, 20 g of aluminum sol (Hunan Jianchang product) was added to the intermediate solid product and mixed thoroughly. The aluminum sol was added in an amount of 3.6 wt.% on a dry basis based on the added weight of the titanium-containing support. The product was then rolled in a ball mill to form a pelletized catalyst. The pellets with a diameter of 2.0 to 3.0 mm were sieved out, dried at 120° C. for 4 h, and then calcined at 750° C. for 8 h to obtain a second pelletized amination catalyst, designated as Catalyst B-2.

[0144] After drying, the catalyst B-2 was tested using a strength tester to find that its strength was greater than 70 N / particle.

[0145] Catalyst B-2 had a composition of 85.4 wt% TiO2, 7.3 wt% V2O5, 6.4 wt% MoO3, 0.4 wt% SiO2, and 0.5 wt% Al2O3.

[0146] Preparation Example 3-3

[0147] This embodiment is used to prepare an exemplary second amination catalyst, which specifically includes the following steps:

[0148] Preparation of vanadyl oxalate: Dissolve 60 g of ammonium metavanadate in 700 g of water and heat in a water bath. Slowly add 130 g of oxalic acid crystals while stirring. Oxidation reaction is carried out at 80°C for 120 min until the color of the slurry changes from yellow to purple to prepare a vanadyl oxalate solution.

[0149] Then, 30 g of sodium tungstate was added, and the mixture was heated on a water bath for 30 minutes to prepare an aqueous solution containing vanadyl oxalate and sodium tungstate.

[0150] The solution was stirred at 70°C. 500g of TiO2 (DuPont R900) and 50g of titanium silicalite (HTS-3 molecular sieve, manufactured by Hunan Jianchang) were added to the solution under continuous stirring. Stirring and aging were continued for 4 hours. The resulting product was dried in an oven at 110°C for 4 hours to remove moisture. The dried material was then added to a grinder and ground for 30 minutes to obtain an intermediate solid product (maximum particle size less than 40 microns).

[0151] In the above steps, the weight ratio of water:vanadium source:acid:metal M source:titanium-containing carrier is 1.272:0.109:0.236:0.0545:1.

[0152] To the intermediate solid product, 15 g of sesbania powder (purchased from Lankao Plant Gum Factory) and 20 g of a 20 wt% aqueous nitric acid solution (4 g of nitric acid) were added and thoroughly mixed. On a dry basis and based on the total weight of the titanium-containing support, the amount of sesbania powder added was 2.7 wt%, and the amount of nitric acid added was 0.73 wt%. The catalyst was then extruded into a strip having a diameter of 2.5 mm through an extruder, dried at 120 ° C for 4 h, and then calcined at 600 ° C for 8 h to obtain a second strip-shaped amination catalyst, designated as catalyst B-3.

[0153] After drying, the strength of catalyst B-3 was measured using a strength tester and found to be 65 N / cm.

[0154] Catalyst B-3 had a composition of 88.3 wt% TiO2, 7.5 wt% V2O5, 3.8 wt% WO3 and 0.4 wt% SiO2.

[0155] Preparation Examples 3-4

[0156] This embodiment is used to prepare an exemplary second amination catalyst, which specifically includes the following steps:

[0157] The same preparation method as that of Preparation Example 3-3 was adopted, except that:

[0158] The weight ratio of water:vanadium source:acid:metal M source:titanium-containing support was adjusted to 1.272:0.091:0.236:0.036:1; the remaining process was the same as that of Preparation Example 3-3. The obtained product was recorded as Catalyst B-4.

[0159] After drying, the strength of catalyst B-4 was measured using a strength tester and found to be 42 N / cm.

[0160] Catalyst B-4 had a composition of 89.4 wt% TiO2, 7.6 wt% V2O5, 2.6 wt% WO3 and 0.4 wt% SiO2.

[0161] Preparation Examples 3-5

[0162] This embodiment is used to prepare an exemplary second amination catalyst, which specifically includes the following steps:

[0163] The same preparation method as Preparation Example 3-3 was adopted, except that the calcination temperature was 450°C, the calcination time was 10 h, and the rest of the process was the same as Preparation Example 3-3; the obtained product was recorded as Catalyst B-5.

[0164] After drying, the strength of the catalyst B-5 was measured using a strength tester and found to be 35 N / cm.

[0165] Catalyst B-5 consists of 88.2 wt% TiO2, 7.6 wt% V2O5, 3.8 wt% WO3 and 0.4 wt% SiO2.

[0166] Preparation Examples 3-6

[0167] The same method as that of Preparation Example 3-3 was used, except that:

[0168] 10 g of ammonium metavanadate, 20 g of oxalic acid crystals, and 10 g of sodium tungstate were used; the remaining procedures were the same as in Preparation Example 3. The resulting product was designated B-6. The weight ratio of water: vanadium source: acid: metal M source: titanium-containing support was 1.091:0.018:0.036:0.018:1.

[0169] After drying, the strength of catalyst B-6 was measured using a strength tester and found to be 23 N / cm.

[0170] Catalyst B-6 consists of 96.8 wt% TiO2, 1.4 wt% V2O5, 1.4 wt% WO3 and 0.4 wt% SiO2.

[0171] The structural performance data of the second amination catalyst products obtained in the above examples and comparative examples are listed in Table 1 below.

[0172] Table 1

[0173]

[0174] Reaction Example 1

[0175] This example is used to exemplify the process of hydrogenating caprolactam, hydrogen and a hydrogenation catalyst to produce hexamethyleneimine.

[0176] 20g of the prepared hydrogenation catalyst was placed in the center of a 24×4×800mm stainless steel reactor, with inert quartz sand filling the ends. Hydrogen was introduced and reduced at 400°C and 1.0 MPa for 24 hours; the temperature and pressure were then reduced to the desired hydrogenation temperature. Molten caprolactam liquid was pumped into the reactor via a metering pump for reaction. After 20 hours of reaction, a product sample was collected, condensed, and analyzed by offline chromatography. The caprolactam conversion and hexamethyleneimine selectivity were calculated based on the product composition. Specific reaction conditions and results are listed in Table 2 below.

[0177]

[0178]

[0179] Table 2

[0180]

[0181] According to the data in Table 2, it can be seen that when the hydrogenation catalyst JQ-1 is used, the caprolactam conversion rate and the hexamethyleneimine selectivity are higher when the reaction temperature is "200-350°C".

[0182] The first product obtained in Reaction Example 1 (the purity of hexamethyleneimine in the first product is 91.4 wt % or more) is subjected to a first separation and purification treatment (eg, distillation treatment) to obtain a hexamethyleneimine-rich product for subsequent amination reaction.

[0183] Reaction Example 2

[0184] This example is used to exemplify the preparation of hexamethylenediamine by amination of hexamethyleneimine, and specifically comprises the following steps:

[0185] 10g of the prepared first amination catalyst and the second amination catalyst were respectively charged into Inert quartz sand was filled at both ends of a jacketed stainless steel reactor. 10 g / h (0.088 mol / h) of hexamethyleneimine was mixed thoroughly with 7.5 g / h (0.44 mol / h) of hot ammonia (the weight ratio of ammonia to hexamethyleneimine was 0.75:1) and N2 (the molar ratio of CPL, ammonia, and nitrogen was 1:5:5) at a temperature of 100°C. The mixture of hexamethyleneimine, ammonia, and nitrogen was brought into contact with the catalyst at a reaction temperature of 300°C and a hexamethyleneimine space velocity of 1.0 h. -1 The amination reaction product was subjected to deamination and dehydration, and then subjected to vacuum distillation to obtain hexamethylenediamine with a purity of 99.0% by weight. In this example, the hexamethyleneimine conversion rate and hexamethylenediamine selectivity were measured and calculated at 20 hours and 200 hours of reaction time, respectively. Specific data are shown in Table 3.

[0186]

[0187]

[0188] Table 3

[0189]

[0190] According to the data in Table 3 above, it can be seen that the method provided by the present disclosure has high hexamethyleneimine conversion rate and hexamethylenediamine selectivity, and the hexamethyleneimine conversion rate and hexamethylenediamine selectivity change little between the reaction time of 200 h and the reaction time of 20 h, and has high stability.

[0191] Among them, compared with B-6, B-1 to B-5 meet the requirements of "the weight ratio of water: vanadium source: acid: metal M source: titanium-containing carrier is (0.5-2.0): (0.05-0.2): (0.05-0.5): (0-0.5): 1" during the preparation process, and the composition of B-1 to B-5 meets the requirements of "5-98 weight% of titanium-containing carrier, 2-30 weight% of vanadium oxide, 0-30 weight% of metal M oxide and / or 0-10 weight% of inorganic oxide". B-1 to B-5 have higher strength and can obtain higher hexamethyleneimine conversion rate, hexamethylenediamine selectivity and better stability in the hexamethyleneimine catalytic reaction.

[0192] Comparing B-1 and B-4 with B-2 to B-3, B-2 to B-3 satisfy the following requirements during the preparation process: "the weight ratio of water: vanadium source: acid: metal M source: titanium-containing support is (0.8 to 1.6): (0.05 to 0.15): (0.1 to 0.3): (0.05 to 0.3): 1", and the composition of B-2 to B3 satisfies the following requirements: "on a dry basis and based on the total weight of the second amination catalyst, comprising 20 to 95 weight percent of a titanium-containing support, 3 to 20 weight percent of a vanadium oxide, 0.5 to 10 weight percent of a metal M oxide and / or 0.2 to 6 weight percent of an inorganic oxide", B-2 to B-3 have higher strength and can obtain higher hexamethyleneimine conversion rate, hexamethylenediamine selectivity and better stability in the hexamethyleneimine catalytic reaction.

[0193] Compared with B-5, B-3 meets the requirements of "calcination temperature of 500-800°C and time of 2-4 hours" during the preparation process. B-3 particles have higher strength and can obtain higher hexamethyleneimine conversion rate, hexamethylenediamine selectivity and better stability in the hexamethyleneimine catalytic reaction.

[0194] Reaction Examples 3 to 6

[0195] The same method as in Reaction Example 2 was used, except that the reaction conditions in Table 4 below were used. The specific reaction results are also listed in Table 4 below.

[0196] Table 4

[0197]

[0198]

[0199] According to the data in Tables 3 and 4, when the catalyst B-3 is used and the amination reaction temperature of Reaction Example 2 is within the range of "200-400°C", the selectivity of hexamethylenediamine in Reaction Example 2 is much higher than the selectivity of Reaction Example 5 at 600°C in Table 4.

[0200] When the B-3 catalyst is used, the amination reaction in Reaction Example 6 satisfies the "weight ratio of ammonia to hexamethyleneimine is 1 to 50:1". Compared with the reaction results in Table 3 of Reaction Example 2, the hexamethyleneimine conversion rate, hexamethylenediamine selectivity and reaction stability in Reaction Example 6 are higher.

[0201] The preferred embodiments of the present disclosure are described in detail above. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

[0202] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0203] In addition, the various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for synthesizing hexamethylenediamine from caprolactam, characterized in that: The method comprises the following steps: (1) contacting caprolactam, hydrogen and a hydrogenation catalyst under catalytic hydrogenation conditions to carry out a catalytic hydrogenation reaction to obtain a first product comprising hexamethyleneimine; (2) contacting the first product, ammonia gas, and an amination catalyst under catalytic amination conditions to perform a catalytic amination reaction to obtain a second product containing hexamethylenediamine; The amination catalyst includes a first amination catalyst; The first amination catalyst comprises an inorganic carrier and a supporting component; the inorganic carrier is selected from one or more of alumina, titania, silica and molecular sieve; The supported components consist of vanadium oxide and phosphorus oxide; Alternatively, the amination catalyst comprises a second amination catalyst; On a dry basis and based on the total weight of the second amination catalyst, the second amination catalyst comprises 5 to 98 weight percent of a titanium-containing support, 2 to 30 weight percent of a vanadium oxide, 0 to 30 weight percent of a metal M oxide, and / or 0 to 10 weight percent of an inorganic oxide, wherein the sum of the weights of the titanium-containing support, the vanadium oxide, the metal M oxide, and the inorganic oxide is 100 weight percent; wherein the titanium-containing support comprises TiO2 and a titanium-containing molecular sieve, the inorganic oxide comprises one or both of Al2O3 and SiO2; and the metal M is selected from one or both of molybdenum and tungsten; The hydrogenation catalyst is selected from copper-based hydrogenation catalysts.

2. The method according to claim 1, characterized in that In step (1), the catalytic hydrogenation conditions include: reaction temperature of 100-400°C, reaction pressure of 0.1-20 MPa, molar ratio of hydrogen to caprolactam of 1-1000:1, weight hourly space velocity of liquid feed of 0.1-10 h -1 .

3. The method according to claim 2, characterized in that The catalytic hydrogenation conditions include: a reaction temperature of 200-350°C, a reaction pressure of 0.5-10 MPa, a molar ratio of hydrogen to caprolactam of 1-50:1, and a weight hourly space velocity of the liquid feed of 0.4-5 h -1 .

4. The method according to claim 1, wherein Based on the total weight of the copper-based hydrogenation catalyst, the copper-based catalyst includes 10-50 wt% CuO, 5-40 wt% ZnO, 20-80 wt% Al2O3 and 0-20 wt% La2O3.

5. The method according to claim 1, characterized in that In step (2), the amination reaction is carried out as a continuous reaction; The catalytic amination conditions include: a reaction temperature of 120-700° C., a weight ratio of ammonia to hexamethyleneimine of 0.1-100:1, an ammonia partial pressure of 0.1-5.0 MPa, and a weight hourly space velocity of hexamethyleneimine of 1-100 h -1 .

6. The method according to claim 5, characterized in that In step (2), the amination reaction is carried out in a fixed bed reactor; The catalytic amination conditions include: a reaction temperature of 200-400° C., a weight ratio of ammonia to hexamethyleneimine of 1-50:1, an ammonia partial pressure of 0.2-3.0 MPa, and a weight hourly space velocity of hexamethyleneimine of 0.5-20 h -1 .

7. The method according to claim 1, characterized in that The method further includes: Before step (2), the first product is subjected to a first separation and purification treatment to obtain a material rich in hexamethyleneimine; and then the hexamethyleneimine-rich material is subjected to the catalytic amination reaction; and After step (2), the second product is subjected to a second separation and purification treatment.

8. The method according to claim 1, characterized in that Based on the total weight of the first amination catalyst, the first amination catalyst includes 5 to 95 weight percent of an inorganic carrier and 2 to 50 weight percent of a support component, and the sum of the weights of the inorganic carrier and the support component is 100 weight percent.

9. The method according to claim 1, characterized in that On a dry basis and based on the total weight of the second hydrogenation catalyst, the second hydrogenation catalyst comprises 20 to 95 weight percent of a titanium-containing support, 3 to 20 weight percent of a vanadium oxide, 0.5 to 10 weight percent of a metal M oxide, and / or 0.2 to 6 weight percent of an inorganic oxide.

10. The method according to claim 1, characterized in that On a dry basis, the weight ratio of TiO2 to the titanium-containing molecular sieve in the titanium-containing carrier is 1:(0.001-5); The titanium-containing molecular sieve includes titanium silicon molecular sieve; the titanium silicon molecular sieve is selected from one or more of HTS molecular sieve, TS-1 molecular sieve, TS-2 molecular sieve and TS-48 molecular sieve.

11. The method according to claim 10, characterized in that On a dry basis, the weight ratio of TiO2 to the titanium-containing molecular sieve in the titanium-containing carrier is 1:(0.05-2).

12. The method according to claim 1, characterized in that The BET specific surface area of ​​the second amination catalyst is 10 to 300 m 2 / g, the total pore volume is 0.02~0.4mL / g, and the micropore volume is 0.01~0.1mL / g.

13. The method according to claim 1, wherein The shape of the second amination catalyst is selected from one or more of spherical, bar, cylindrical, ring, clover, four-leaf, honeycomb and butterfly shapes.

14. The method according to claim 1, wherein In step (2), the second amination catalyst is prepared by a preparation method comprising the following steps: S1, contacting a vanadium source, water and an acid to perform an oxidation reaction; adding a metal M source and a titanium-containing support to the oxidation reaction product to obtain a mixture; performing a first drying treatment on the mixture to obtain an intermediate solid product; S2. The intermediate solid product is subjected to a molding process, a second drying process and a calcination process in sequence.

15. The method according to claim 14, characterized in that In step S1, the weight ratio of water:vanadium source:acid:metal M source:titanium-containing carrier is (0.5-2.0):(0.05-0.2):(0.05-0.5):(0-0.5):

1.

16. The method according to claim 15, characterized in that In step S1, the weight ratio of water:vanadium source:acid:metal M source:titanium-containing carrier is (0.8-1.6):(0.05-0.15):(0.1-0.3):(0.05-0.3):

1.

17. The method according to claim 14, characterized in that In step S1, the vanadium source is selected from one or more of ammonium metavanadate, sodium metavanadate and vanadium pentoxide; The acid is selected from one or more of oxalic acid, citric acid and nitric acid; The metal M source is selected from one or more of nitrates, phosphates and chlorides of the metal M element.

18. The method according to claim 17, characterized in that The metal M source is selected from one or more of ammonium molybdate tetrahydrate and sodium tungstate.

19. The method according to claim 14, wherein Step S1 includes: dissolving the vanadium source in water, then adding the acid to the vanadium source solution to carry out the oxidation reaction to obtain an oxidation reaction product; Adding the metal M source to the oxidation reaction product and performing a first mixing to obtain a first mixture, wherein the first mixing temperature is 50-100° C. and the time is 60-300 min; Adding the titanium-containing support to the first mixture and performing a second mixing to obtain a second mixture, wherein the second mixing is performed at a temperature of 30 to 80° C. and for a time of 30 to 300 minutes; The second mixture is subjected to the first drying treatment, and the obtained product is ground to obtain the intermediate solid product; the temperature of the first drying treatment is 80-150°C.

20. The method according to claim 14, wherein The molding process in step S2 is extrusion molding; step S2 comprises: mixing the intermediate solid product with a pore-enlarging agent and an extrusion aid, and then sequentially performing the molding process, a second drying process, and a calcination process; or The molding process in step S2 is ball molding, and step S2 further includes: mixing the intermediate solid product with an inorganic oxide source, and then sequentially performing the molding process, the second drying process, and the calcination process.

21. The method according to claim 20, characterized in that In step S2, the amount of the pore-enlarging agent added is 0.5 to 10% by weight, based on the weight of the titanium-containing carrier added, and the amount of the extrusion aid added is 0.5 to 4% by weight; or The amount of the inorganic oxide source added is 0.1 to 5 wt % based on dry basis and based on the added weight of the titanium-containing support.

22. The method according to claim 21, characterized in that In step S2, the amount of the pore-enlarging agent added is 1 to 5 weight percent based on the weight of the titanium-containing carrier added; the amount of the extrusion aid added is 0.5 to 2 weight percent; or The amount of the inorganic oxide source added is 0.1 to 2.0 wt % based on dry basis and based on the added weight of the titanium-containing support.

23. The method according to claim 20, characterized in that In step S2, the pore-enlarging agent is selected from one or more of sesbania powder, paraffin, stearic acid, glycerol, starch, polyethylene glycol, polyvinyl alcohol, polyethylene oxide, polyacrylamine, cellulose methyl ether, cellulose, polyol and graphite; The extrusion aid is selected from one or more of organic acids, inorganic acids and inorganic bases; The inorganic oxide source is added in the form of an inorganic oxide or an inorganic oxide precursor; The inorganic oxide includes one or both of Al2O3 and SiO2; and the inorganic oxide precursor is selected from one or more of aluminum sol, silica sol and water glass.

24. The method according to claim 23, wherein The extrusion aid is selected from one or more of oxalic acid, tartaric acid, citric acid, nitric acid, hydrochloric acid, acetic acid, formic acid, ammonia water, sodium hydroxide and potassium hydroxide.

25. The method according to claim 14, wherein In step S2, the conditions of the second drying process include: temperature of 80-200°C; time of 1-10 hours; The calcination conditions include: temperature of 200-900° C.; and time of 0.5-10 h.

26. The method according to claim 25, characterized in that In step S2, the conditions of the second drying treatment include: temperature of 100-150°C; time of 2-4 hours; The calcination conditions include: a temperature of 500-800° C. and a time of 2-4 hours.

Images