Method for producing methyl pentamethylene diamine and methylpiperidine through hydrogenation of methyl glutaronitrile

Abstract

The invention provides a method for producing methyl pentamethylene diamine and methylpiperidine through hydrogenation of methyl glutaronitrile, and belongs to the technical field of chemical engineering. Comprising the following steps: a mixed solution of 2-methylglutaronitrile and a hydrogen-dissolving solvent passes through a feeding pump and a preheater, and enters the lower part of a pipeline reactor together with a liquid-solid phase mixed material from a high-pressure circulating pump, hydrogen enters a gas distributor at the bottom of the pipeline reactor, and a formed gas-liquid-solid three-phase material is subjected to a catalytic hydrogenation reaction in a rising process from the bottom of the pipeline reactor; carrying out gas phase separation; unreacted hydrogen is circulated; and liquid-solid materials at the bottom of the high-pressure gas-liquid-solid phase separator are returned to the pipeline reactor through the high-pressure circulating pump. A middle produced liquid phase is sent to a low-pressure liquid-solid phase separator through pressure reduction, a catalyst separated at the bottom is recovered to a catalyst preparation system, the middle produced liquid phase enters a hydrogen-dissolving solvent recovery tower, a hydrogen-dissolving solvent recovered at the tower top is sent back to a raw material tank, and a product is obtained at the tower bottom. The method is more stable, reaction and separation equipment are small in size, and the production capacity is high.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a method for producing methylpentanediamine and methylpiperidine by hydrogenating methylglutaronitrile. Background Art

[0002] At present, the industrial production method of adiponitrile mainly includes butadiene hydrocyanation, adipic acid ammoniation, caprolactam ammoniation hydrogenation and acrylonitrile electrolytic dimerization. The mainstream route is butadiene hydrocyanation, but the production process of this route will produce 15-20% of 2-methylglutaronitrile (MGN) as a byproduct. Therefore, as adiponitrile continues to expand production, it brings a large amount of 2-methylglutaronitrile. How to improve the economic value of 2-methylglutaronitrile has important industrial significance. Among them, the route of 2-methylglutaronitrile to obtain 2-methylpentanediamine (MPMD) and 3-methylpiperidine (MPP) by catalytic hydrogenation has great economic value. 2-Methylpentanediamine is an important chemical and pharmaceutical intermediate, mainly used for the production of polyamide plastics, films and fibers, polyamide adhesives and printing resins, epoxy resin curing treatment agents. 3-Methylpiperidine is an important organic solvent, and can also be used to prepare coatings, dyes, dye additives and fine chemical products. 2-Methylpentanediamine and 3-methylpiperidine can be hydrogenated to obtain the important organic intermediate β-methylpyridine, which can be used to synthesize nicotinic acid and nicotinamide, etc. It is in great demand in fine chemical industries such as feed, pesticides, medicines and food, and has good market prospects.

[0003] Usually, dinitrile compounds are catalytically hydrogenated to obtain the corresponding aliphatic diamine compounds. The commonly used catalyst is a Raney nickel catalyst. At the same time, the intermediate product aminonitrile in the hydrogenation process of dinitrile compounds is prone to side reactions to produce corresponding nitrogen-containing heterocyclic compounds. "Petrochemicals" Vol. 39, 2010 reported the use of amorphous Fe-Mo-Ni-Al catalyst to catalyze the hydrogenation of glutaronitrile to prepare pentamethylenediamine. Under the optimized conditions of 15% catalyst dosage, 0.25% NaOH co-catalyst dosage, 3MPa reaction pressure, and 70°C reaction temperature, the conversion rate of glutaronitrile was 100% and the selectivity of pentamethylenediamine reached 66.8%. The document Appl. Catal. A: Gen. 2009 reported that the use of Raney nickel catalyst doped with a small amount of Mo, Cr or Fe additives can significantly increase the yield of aliphatic diamine products.

[0004] U.S. Patent No. 4,885,391 discloses a method for converting MGN into MPMD by hydrogenation. The raw material MGN is substantially completely converted under the conditions of 80-150°C, 2.8-17.2 MPa and water using a chromium-modified Raney cobalt catalyst. The selectivity of the products MPMD and MPP are 70.8% and 13.4%, respectively, but the heavy byproduct is 11.8%.

[0005] Patent CN101990532 / WO2009121704 discloses a method for preparing 2-methylpentanediamine and 3-methylpiperidine, using a nickel and chromium doped Raney cobalt catalyst, under the conditions of reaction pressure less than 5.0MPa, 60-160°C temperature and the presence of a strong alkaline inorganic compound, MGN can be completely converted, and the selectivity of the products MPMD and MPP is 80% and 20% respectively; for a dinitrile mixture, MGN is completely converted, and the selectivity of the products MPMD and MPP is 64% and 28% respectively. French patents FR2306204-2306208 report a method for converting MGN into a mixture of MPMD and MPP by hydrogenation based on nickel or Raney nickel catalyst at a certain temperature and hydrogen pressure, and the ratio of the products MPMD and MPP can be adjusted by changing the solvent and catalyst used. The above related reports or patent disclosures mainly focus on the use of a kettle reactor for high-pressure discontinuous hydrogenation process, which has the problems of long reaction time, discontinuous production and safety factors.

[0006] Chinese invention patent CN11137820.B discloses the use of a Ru- and Mo-doped Raney nickel composite catalyst and a bubbling flow reactor to hydrogenate 2-methylglutaronitrile to produce 2-methylpentanediamine, with a reaction temperature of 70-100°C, 2.3-6.0 MPa, a reaction time of 15-50 min, and a hydrogen to liquid flow rate ratio of 10-20:1. However, the process still has problems such as long reaction time, high reaction pressure, low hydrogen utilization, and high selectivity of by-products. The operational stability is still unclear and there are no reports on industrialization. Summary of the invention

[0007] The purpose of the present invention is to provide a method for producing methylpentanediamine and methylpiperidine by hydrogenating methylglutaronitrile, which overcomes the serious wear and blockage of equipment caused by the current use of high-pressure plunger pumps or diaphragm pumps to transport liquid-solid slurries, and solves the problems of frequent shutdown of equipment for maintenance and unstable materials in the production system.

[0008] The technical solution of the present invention is achieved in this way: A method for producing methylpentanediamine and methylpiperidine by hydrogenating methylglutaronitrile comprises the following steps: (1) The mixed liquid of 2-methylglutaronitrile and hydrogen-soluble solvent in the raw material tank is pressurized by the feed pump and heated by the preheater, and enters the lower feed pipe of the pipeline reactor together with the liquid-solid phase mixed material from the high-pressure circulation pump. The hydrogen from the hydrogen circulation machine and the fresh supplementary hydrogen merge into the gas distributor at the bottom of the pipeline reactor. The hydrogen and the liquid-solid phase materials form a gas-liquid-solid three-phase material and undergo a hydrogenation reaction during the process of rising from the bottom of the pipeline reactor.

[0009] (2) The gas-liquid-solid three-phase material is separated into gas phase-liquid-solid phase at the upper part of the reactor, and the liquid-solid phase overflows into the high-pressure gas-liquid-solid phase separator for further gas phase separation; the separated hydrogen is combined and cooled and separated; it is returned to the bottom of the pipeline reactor by the hydrogen circulation machine; the liquid and solid phase materials at the bottom of the high-pressure gas-liquid-solid phase separator are returned to the lower part of the pipeline reactor by the high-pressure circulation pump.

[0010] (3) The liquid phase extracted from the middle of the high-pressure gas-liquid-solid phase separator is sent to the low-pressure liquid-solid phase separator after decompression. The liquid phase extracted from the middle of the low-pressure liquid-solid phase separator enters the hydrogen-soluble solvent recovery tower. The hydrogen-soluble solvent recovered at the top of the tower is sent back to the raw material tank. The product methylpentanediamine and methylpiperidine mixed liquid at the bottom of the tower is sent to the product intermediate tank.

[0011] (4) The small amount of catalyst separated by the low-pressure liquid-solid phase separator is recovered to the catalyst configuration system for online catalyst regeneration and replenishment.

[0012] As a further improvement of the present invention, the mixed liquid in the raw material tank is prepared according to the mass ratio of 2-methylglutaronitrile to hydrogen-soluble solvent of 1.0-4.0:1.0, preferably 1.0:1.0; the hydrogen-soluble solvent is methanol or ethanol, preferably ethanol; the feed pump is pressurized to 2.0-3.0MPa, preferably 2.3-2.5MPa; the mixed liquid is preheated to 50-90°C, preferably 55-65°C, by a preheater.

[0013] As a further improvement of the present invention, the mixed liquid of methylglutaronitrile and hydrogen-soluble solvent is pressurized by a feed pump and preheated by a preheater, and enters the liquid-solid material feed pipe at the bottom of the pipeline reactor together with the liquid-solid materials from the high-pressure circulation pump, wherein the volume flow ratio of the liquid-solid materials from the high-pressure circulation pump to the mixed liquid of 2-methylglutaronitrile and hydrogen-soluble solvent from the feed pump is 300-600, preferably 400. The residence time of the mixed liquid phase in the reaction tube is 5-15 seconds, preferably 6 seconds.

[0014] As a further improvement of the present invention, the hydrogen from the hydrogen circulation machine and the fresh supplementary hydrogen are combined and enter the gas distributor at the bottom of the pipeline reactor, wherein the diameter of a single hole on the distributor orifice plate is 1.0-2.0 mm and is evenly distributed; the volume flow ratio of the hydrogen (standard state) entering the bottom of the pipeline reactor to the liquid-solid phase material of the high-pressure circulation pump is 0.3-0.5:1.0, preferably 0.4:1.0.

[0015] As a further improvement of the present invention, the pipeline reactor is a sleeve-type empty tube bubbling reactor, the inner tube is the reaction section, and the outer tube is the water-cooling section. The height of the reaction section is the length from the lower liquid-solid phase material feed pipe mouth to the upper liquid-solid phase overflow port, and the diameter-to-height ratio of the pipeline reactor reaction section is 60-80, preferably 70. The gas distributor arranged at the bottom is a perforated plate type, and the lower liquid-solid phase material feed pipe is arranged above the gas distributor. The reaction pressure of the pipeline reactor reaction section is 2.0-3.0MPa, preferably 2.3-2.5MPa; the reaction temperature is 50-90°C, preferably 55-65°C. The hydrogenation reaction of 2-methylglutaronitrile is an exothermic reaction, and the outer tube cooling section is used for water cooling to transfer heat, and the reaction temperature is controlled to be 50-90°C, preferably 55-65°C.

[0016] As a further improvement of the present invention, the gas-liquid-solid three-phase material for hydrogenation reaction during the process of rising from the bottom of the reactor is: the gas phase is hydrogen, the solid phase is a catalyst, the catalyst is a modified nickel catalyst, and the liquid phase is a mixed liquid composed of 2-methylglutaronitrile, 2-methylpentanediamine, 3-methylpiperidine, hydrogenation by-products, alkaline auxiliary agents and hydrogen-soluble solvents. During the process of the gas-liquid-solid three-phase material rising from the bottom of the reactor, the solid phase catalyst is 10-20% of the mass content of the three-phase mixed liquid, preferably 13%; the alkaline auxiliary agent is sodium hydroxide or potassium hydroxide, and the proportion is 0.01-0.5% of the mass content of the three-phase mixed liquid, preferably 0.3%.

[0017] Preferably, the preparation method of the modified nickel catalyst is as follows: S1. Preparation of composite metal layered oxide: dissolving aluminum salt and magnesium salt in water, adding alkali, heating for crystallization, filtering, washing, drying, and calcining to obtain a composite metal layered oxide; S2. Magnetic modification: adding a composite metal layered oxide to water, adding ferric chloride and ferrous chloride, adding ammonia water dropwise under inert gas protection, heating and stirring to react, centrifuging, washing, drying, and calcining to obtain a magnetic composite metal layered oxide; S3. Graphene coating: dispersing graphene oxide in water, adding magnetic composite metal layered oxide, uniformly dispersing by ultrasonication, spray drying, and reducing with hydrazine hydrate vapor to obtain graphene-coated magnetic composite metal layered oxide; S4. Preparation of an impregnation solution: dissolving a nickel salt, a molybdenum salt and a chromium salt in water to obtain an impregnation solution; S5. Preparation of modified nickel catalyst: adding graphene-coated magnetic composite metal layered oxide to the impregnation solution, heating to evaporate the solvent, and calcining to obtain a modified nickel catalyst.

[0018] Common Raney nickel catalyst has the disadvantages of poor activity and stability, easy breakage, and easy loss of Ni and Al during the reaction process, which greatly affects the catalytic activity. The catalyst modified by Mo and Cr can not only improve the catalytic activity, but also reduce the loss of Ni and Al. In addition, in the gas-liquid-solid three-phase reaction, changing the stirring speed can change the contact surface and mass transfer surface area of ​​the three-phase reaction. In order to overcome the influence of the catalyst external diffusion, a higher stirring speed is often used, which also causes the catalyst to be seriously pulverized. The shear force caused by high-speed stirring can cause the wear of the catalyst, thereby greatly reducing the catalytic activity. At the same time, due to the serious pulverization in the reaction, it is extremely difficult to separate it from the product. The present invention prepares a composite metal layered oxide, and the magnetic iron oxide of the load, and generates Ni in situ, thereby greatly reducing the catalyst deactivation and loss due to pulverization, and improving the activity of the catalytic reaction.

[0019] The present invention chemically vapor deposits a carbon layer on the surface of the prepared magnetic composite layered metal oxide, which greatly increases the specific surface area of ​​the carrier on the one hand, thereby increasing the metal loading capacity, and on the other hand improves the mechanical properties of the carrier and its anti-powdering ability, so that the prepared catalyst can well resist stirring pulverization and wear, improves the stability of the catalyst and maintains a high catalytic activity after multiple recycling.

[0020] Preferably, in step S1, the aluminum salt is aluminum nitrate, the magnesium salt is magnesium chloride, magnesium nitrate or magnesium sulfate, the molar ratio of the aluminum salt to the magnesium salt is 1:1, the base is NaOH or KOH, the heating crystallization temperature is 85-95°C, the time is 0.5-1h, and the calcination temperature is 400-500°C, and the time is 1-2h.

[0021] Preferably, in step S2, the mass ratio of the composite metal layered oxide, ferric chloride, ferrous chloride and ammonia water is 10:3.24:1.26:3-5, the temperature of the heating and stirring reaction is 60-70°C, the time is 2-4h, and the calcination temperature is 400-500°C, and the time is 1-2h.

[0022] Preferably, in step S3, the mass ratio of graphene oxide to magnetic composite metal layered oxide is 2-3:7, and the reduction time is 10-12 hours.

[0023] Preferably, in step S4, the mass ratio of the nickel salt, the molybdenum salt and the chromium salt is 15-20:2-3:1-2, the nickel salt is nickel nitrate or nickel chloride, the molybdenum salt is molybdenum nitrate, and the chromium salt is chromium nitrate.

[0024] Preferably, in step S5, the mass ratio of the graphene-coated magnetic composite metal layered oxide to the impregnation solution is 1:3-5, the calcination temperature is 350-450° C., and the calcination time is 1-2 h.

[0025] As a further improvement of the present invention, the gas-liquid-solid three-phase material is separated from unreacted hydrogen at the top of the reactor and in a high-pressure gas-liquid-solid phase separator, and enters a shell-and-tube water cooler at the top of the pipeline reactor. After cooling, the temperature is 30-35°C, and the separated hydrogen-dissolving solvent is refluxed to the pipeline reactor. The unreacted hydrogen is returned to the bottom of the pipeline reactor by a hydrogen circulation machine, and fresh hydrogen is supplemented by a hydrogen supply station.

[0026] As a further improvement of the present invention, the liquid-solid phase overflows from the upper part of the pipeline reactor and enters the high-pressure gas-liquid-solid phase separator. The high-pressure gas-liquid-solid phase separator is provided with a lateral cyclone guide pipe to promote the solid phase to settle to the bottom. The bottom is the liquid-solid phase material containing 10-15% catalyst, which is then returned to the lower feed port of the pipeline reactor by a high-pressure circulation pump.

[0027] As a further improvement of the present invention, the liquid phase extracted from the middle of the high-pressure gas-liquid-solid phase separator is sent to a low-pressure liquid-solid phase separator after decompression, and the liquid-solid phase materials containing 1-3% catalyst enter the low-pressure liquid-solid phase separator provided with a lateral cyclone guide pipe, and the operating pressure of the low-pressure liquid-solid phase separator is normal pressure.

[0028] As a further improvement of the present invention, a small amount of catalyst separated by the low-pressure liquid-solid phase separator is recovered to a catalyst configuration system; the catalyst configuration system is protected by nitrogen, and the recovered 1-3% catalyst and the supplemented fresh catalyst are regenerated by 20% sodium hydroxide alkaline washing, and after regeneration, the catalyst is mixed with an appropriate hydrogen-soluble solvent and then fed into the reaction system using high-pressure nitrogen (slightly higher than the reaction system pressure) by using the pressure difference.

[0029] Preferably, the pressure of the high-pressure nitrogen is 0.2-0.5 MPa higher than the pressure of the reaction system.

[0030] As a further improvement of the present invention, the liquid phase extracted from the middle of the low-pressure liquid-solid phase separator enters a hydrogen-dissolving solvent recovery tower, the operating pressure of the recovery tower is atmospheric pressure, the cooling reflux temperature at the top of the recovery tower is 30-35°C, and the reflux ratio is 1-2; the reboiling temperature at the bottom of the recovery tower is 75-80°C, and the outlet material at the bottom of the recovery tower is a mixed solution of 2-methylpentanediamine and 3-methylpiperidine, which is cooled to 30-35°C and sent to the product intermediate tank.

[0031] The present invention has the following beneficial effects: 1. The present invention reduces the particle size of the catalyst and adds a hydrogen dissolving agent according to the dinitrile hydrogenation reaction mechanism, which is beneficial to increase the hydrogenation site and the hydrogen gas-liquid mass transfer rate, and improves the direction of hydrogenation. Selecting an appropriate amount of hydrogen dissolving solvent as a heat transfer carrier is beneficial to the removal of reaction heat and the stability of the reaction section temperature zone. At the same time, adding an appropriate amount of alkaline additive is beneficial to reduce the by-products produced by deamination cyclization and alkylation; 2. The present invention adopts pipeline reactor, high-pressure gas-liquid solid phase separator and low-pressure liquid-solid phase separator; there are no complex internal parts in the device, the fluid flow is stable and the resistance is small, the relative reaction temperature and pressure are low, and the production operation is simple and safe. The production process uses three-phase materials to carry out multiple rapid cycles and enhanced hydrogenation in the tubular reaction section, and the hydrogen partial pressure in the reaction section is high and the single-pass hydrogen utilization rate is high. The reaction and separation equipment is small in size and has a large production capacity; 3. The present invention utilizes the pressure difference principle to recycle and regenerate the catalyst online and replenish it to the reaction system, thus solving the problem of the stability of the catalyst mass content and activity in the reaction system. It overcomes the serious equipment wear and blockage caused by the current use of high-pressure plunger pumps or diaphragm pumps to transport liquid-solid slurries, and solves the problem of frequent equipment shutdowns for maintenance and unstable materials in the production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 This is a process flow chart of Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Graphene oxide, with a thickness of <5 nm, an oxygen content of about 35%, and a sheet diameter of about 20 μm, was purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.

[0036] Preparation Example 1 The preparation of modified nickel catalyst is as follows: S1. Preparation of composite metal layered oxide: 0.1 mol aluminum nitrate and 0.1 mol magnesium nitrate were dissolved in 200 mL water, 0.5 mL NaOH was added, heated to 85°C, crystallized for 0.5 h, filtered, washed, dried, and calcined at 400°C for 1 h to obtain a composite metal layered oxide; S2. Magnetic modification: 10 g of composite metal layered oxide was added to 200 mL of water, 3.24 g of ferric chloride and 1.26 g of ferrous chloride were added, 3 g of ammonia water was added dropwise under argon protection, the mixture was heated to 60 ° C, stirred for 2 h, centrifuged, washed, dried, and calcined at 400 ° C for 1 h to obtain a magnetic composite metal layered oxide; S3. Graphene coating: 20 mg of graphene oxide was dispersed in 200 mL of water, 70 mg of magnetic composite metal layered oxide was added, 1000 W ultrasonic dispersion was performed for 10 min, spray dried, and reduced with hydrazine hydrate vapor for 10 h to obtain a graphene-coated magnetic composite metal layered oxide; S4 Preparation of an impregnation solution: 1.5 g of nickel nitrate, 0.2 g of molybdenum nitrate and 0.1 g of chromium nitrate were dissolved in 300 mL of water and stirred for 15 min to obtain an impregnation solution; S5. Preparation of modified nickel catalyst: 10 g of graphene-coated magnetic composite metal layered oxide was added to 30 g of the impregnation solution, heated to evaporate the solvent, and calcined at 350° C. for 1 h to obtain a modified nickel catalyst.

[0037] Preparation Example 2 The preparation of modified nickel catalyst is as follows: S1. Preparation of composite metal layered oxide: 0.1 mol aluminum nitrate and 0.1 mol magnesium nitrate were dissolved in 200 mL water, 0.5 mL NaOH was added, heated to 95 ° C, crystallized for 1 h, filtered, washed, dried, and calcined at 500 ° C for 2 h to obtain a composite metal layered oxide; S2. Magnetic modification: 10 g of composite metal layered oxide was added to 200 mL of water, 3.24 g of ferric chloride and 1.26 g of ferrous chloride were added, 5 g of ammonia water was added dropwise under argon protection, the mixture was heated to 70 ° C, stirred for 4 h, centrifuged, washed, dried, and calcined at 500 ° C for 2 h to obtain a magnetic composite metal layered oxide; S3. Graphene coating: 30 mg of graphene oxide was dispersed in 200 mL of water, 70 mg of magnetic composite metal layered oxide was added, 1000 W ultrasonic dispersion was performed for 10 min, spray dried, and reduced with hydrazine hydrate vapor for 12 h to obtain graphene-coated magnetic composite metal layered oxide; S4 Preparation of an impregnation solution: 2g of nickel nitrate, 0.3g of molybdenum nitrate and 0.2g of chromium nitrate were dissolved in 300mL of water and stirred for 15min to obtain an impregnation solution; S5. Preparation of modified nickel catalyst: 10 g of graphene-coated magnetic composite metal layered oxide was added to 50 g of the impregnation solution, heated to evaporate the solvent, and calcined at 450° C. for 2 h to obtain a modified nickel catalyst.

[0038] Preparation Example 3 The preparation of modified nickel catalyst is as follows: S1. Preparation of composite metal layered oxide: 0.1 mol aluminum nitrate and 0.1 mol magnesium nitrate were dissolved in 200 mL water, 0.5 mL NaOH was added, heated to 90°C, crystallized for 1 h, filtered, washed, dried, and calcined at 450°C for 1.5 h to obtain composite metal layered oxide; S2. Magnetic modification: 10 g of composite metal layered oxide was added to 200 mL of water, 3.24 g of ferric chloride and 1.26 g of ferrous chloride were added, 4 g of ammonia water was added dropwise under argon protection, heated to 65 ° C, stirred for 3 h, centrifuged, washed, dried, and calcined at 450 ° C for 1.5 h to obtain a magnetic composite metal layered oxide; S3. Graphene coating: 25 mg of graphene oxide was dispersed in 200 mL of water, 70 mg of magnetic composite metal layered oxide was added, 1000 W ultrasonic dispersion was performed for 10 min, spray dried, and reduced with hydrazine hydrate vapor for 11 h to obtain graphene-coated magnetic composite metal layered oxide; S4. Preparation of an impregnation solution: 1.7 g of nickel nitrate, 0.25 g of molybdenum nitrate and 0.15 g of chromium nitrate were dissolved in 300 mL of water and stirred for 15 min to obtain an impregnation solution; S5. Preparation of modified nickel catalyst: 10 g of graphene-coated magnetic composite metal layered oxide was added to 40 g of the impregnation solution, heated to evaporate the solvent, and calcined at 400° C. for 1.5 h to obtain a modified nickel catalyst.

[0039] Comparative Preparation Example 1 is different from Preparation Example 3 in that step S2 is not performed, which is as follows: S1. Preparation of composite metal layered oxide: 0.1 mol aluminum nitrate and 0.1 mol magnesium nitrate were dissolved in 200 mL water, 0.5 mL NaOH was added, heated to 90°C, crystallized for 1 h, filtered, washed, dried, and calcined at 450°C for 1.5 h to obtain composite metal layered oxide; S2. Graphene coating: 25 mg of graphene oxide was dispersed in 200 mL of water, 70 mg of composite metal layered oxide was added, ultrasonic dispersion was performed at 1000 W for 10 min, spray dried, and reduced with hydrazine hydrate vapor for 11 h to obtain graphene-coated composite metal layered oxide; S3. Preparation of an impregnation solution: 1.7 g of nickel nitrate, 0.25 g of molybdenum nitrate and 0.15 g of chromium nitrate were dissolved in 300 mL of water and stirred for 15 min to obtain an impregnation solution; S4. Preparation of modified nickel catalyst: 10 g of graphene-coated composite metal layered oxide was added to 40 g of the impregnation solution, heated to evaporate the solvent, and calcined at 400° C. for 1.5 h to obtain a modified nickel catalyst.

[0040] Comparative Preparation Example 2 is different from Preparation Example 3 in that step S3 is not performed, which is as follows: S1. Preparation of composite metal layered oxide: 0.1 mol aluminum nitrate and 0.1 mol magnesium nitrate were dissolved in 200 mL water, 0.5 mL NaOH was added, heated to 90°C, crystallized for 1 h, filtered, washed, dried, and calcined at 450°C for 1.5 h to obtain composite metal layered oxide; S2. Magnetic modification: 10 g of composite metal layered oxide was added to 200 mL of water, 3.24 g of ferric chloride and 1.26 g of ferrous chloride were added, 4 g of ammonia water was added dropwise under argon protection, heated to 65 ° C, stirred for 3 h, centrifuged, washed, dried, and calcined at 450 ° C for 1.5 h to obtain a magnetic composite metal layered oxide; S3. Preparation of an impregnation solution: 1.7 g of nickel nitrate, 0.25 g of molybdenum nitrate and 0.15 g of chromium nitrate were dissolved in 300 mL of water and stirred for 15 min to obtain an impregnation solution; S4. Preparation of modified nickel catalyst: 10 g of magnetic composite metal layered oxide was added to 40 g of impregnation solution, heated to evaporate the solvent, and calcined at 400° C. for 1.5 h to obtain a modified nickel catalyst.

[0041] Comparative Preparation Example 3 is compared with Preparation Example 3, except that no platinum nitrate is added in step S4, specifically as follows: S4. Preparation of impregnation solution: 1.7 g of nickel nitrate and 0.4 g of chromium nitrate were dissolved in 300 mL of water and stirred for 15 min to prepare an impregnation solution.

[0042] Comparative Preparation Example 4 is different from Preparation Example 3 in that no chromium nitrate is added in step S4, as follows: S4. Preparation of an impregnation solution: 1.7 g of nickel nitrate and 0.4 g of molybdenum nitrate were dissolved in 300 mL of water and stirred for 15 min to obtain an impregnation solution.

[0043] Comparative Preparation Example 5 is compared with Preparation Example 3, except that molybdenum nitrate and chromium nitrate are not added in step S4, specifically as follows: S4. Preparation of impregnation solution: 2.1 g of nickel nitrate was dissolved in 300 mL of water and stirred for 15 min to prepare an impregnation solution.

[0044] Test Example 1 The specific surface areas of the modified nickel catalysts prepared in Preparation Examples 1-3 and Comparative Preparation Examples 1-5 were measured using an ASAP2460 fully automatic specific surface and porosity analyzer produced by Micromeritics Instruments, Inc., USA. The results are shown in Table 1.

[0045] Table 1

[0046] It can be seen from the above table that the modified nickel catalysts prepared in Preparation Examples 1-3 of the present invention have a relatively high specific surface area.

[0047] Example 1 The process flow of this embodiment is as follows Figure 1 As shown, the specific steps include: (1) A mixed solution is prepared in a raw material tank according to a mass ratio of 2-methylglutaronitrile to ethanol of 1.0±0.2; the mixed solution is pressurized to 2.3±0.1MPa (gauge pressure) by a feed pump, heated to 55±5°C by an electric preheater, and then added to the liquid-solid phase mixed material from the high-pressure circulation pump and enters the lower feed pipe of the pipeline reactor. The volume flow rate of the liquid-solid phase material of the high-pressure circulation pump is 400±50 times the volume flow rate of the mixed solution from the feed pump. The hydrogen from the hydrogen circulation machine and the fresh supplementary hydrogen are combined and enter the gas distributor at the bottom of the pipeline reactor. The hydrogen flow rate (standard state) is controlled at 0.4±0.1 times the volume flow rate of the liquid-solid phase material of the high-pressure circulation pump.

[0048] (2) The hydrogen and liquid-solid phase materials at the bottom of the pipeline reactor form a gas-liquid-solid three-phase material, and a hydrogenation reaction is carried out during the rising process from the bottom of the pipeline reactor.

[0049] Specifically, the pipeline reactor is a sleeve-type empty tube bubbling reactor, the inner tube is the reaction section, the outer tube is the water cooling section, and the top is a gas phase shell-and-tube water cooling separator. The diameter-to-height ratio of the pipeline reactor reaction section is selected as 70. The inner tube reaction pressure of the pipeline reactor is controlled at 2.3±0.1MPa (gauge pressure); the reaction temperature is controlled at 60±5℃, and the outer tube cooling section water cooling heat transfer is used to assist in controlling the reaction temperature. Three temperature points are set in the vertical direction of the reaction section, with the middle point as the control point.

[0050] Specifically, the gas-liquid-solid three-phase materials in the tubular reactor are: the gas phase is hydrogen, the solid phase is the catalyst prepared in Preparation Example 1, and the liquid phase is a mixed solution of 2-methylglutaronitrile, 2-methylpentanediamine, 3-methylpiperidine, hydrogenation by-products, sodium hydroxide auxiliary agent and ethanol. The catalyst accounts for 13±5% of the mass content of the three-phase mixed solution; the alkaline auxiliary agent is sodium hydroxide, accounting for 0.3±0.1% of the mass content of the three-phase mixed solution.

[0051] (3) The gas-liquid-solid three-phase material is separated into gas-liquid-solid phases at the top of the reactor. The liquid-solid phase material enters the high-pressure gas-liquid-solid phase separator laterally through the overflow port to further separate the unreacted hydrogen. The two streams of unreacted hydrogen enter the tube-in-tube water cooler at the top of the pipeline reactor. After cooling, the temperature is controlled at 32±2°C. The separated ethanol flows back to the pipeline reactor. The unreacted hydrogen is returned to the bottom of the pipeline reactor by the hydrogen circulation machine, and fresh hydrogen is added from the hydrogen supply station to maintain the hydrogen addition amount.

[0052] (4) The liquid-solid phase overflow at the top of the reactor enters a high-pressure gas-liquid-solid phase separator with a lateral cyclone guide pipe, promoting the solid phase catalyst to settle at the bottom to form a mixed liquid with a thicker solid content, and then returns to the lower feed port of the pipeline reactor by a high-pressure circulation pump. The liquid phase containing 2% catalyst is extracted from the middle of the high-pressure gas-liquid-solid phase separator, and after decompression, it enters a low-pressure liquid-solid phase separator with a lateral cyclone guide pipe. The operating pressure of the low-pressure liquid-solid phase separator is atmospheric pressure, and the catalyst separated at the bottom is recovered to the catalyst configuration system.

[0053] (5) The liquid phase is extracted from the middle of the low-pressure liquid-solid phase separator and enters the hydrogen-dissolving solvent recovery tower. The operating pressure of the recovery tower is atmospheric pressure. The cooling reflux temperature at the top of the recovery tower is 32±2° C., and the reflux ratio is 1.5. The reboiling temperature at the bottom of the recovery tower is 77±2° C. The outlet material at the bottom of the recovery tower is a mixed liquid of 2-methylpentanediamine and 3-methylpiperidine, which is cooled to 32±2° C. and sent to the product intermediate tank for further dehydration, dealkalization, removal of by-products, separation and purification.

[0054] (6) Take samples from the outlet of the high-pressure circulation pump every 8 hours to test the catalyst content in the material, and regularly discharge part of the catalyst configuration system. The catalyst configuration system is protected by nitrogen. The recovered and regularly discharged catalysts and the replenished fresh catalysts are regenerated and activated by 20% sodium hydroxide alkali washing. The prepared catalysts are then sent into the reaction system by high-pressure nitrogen (0.3Mpa higher than the reaction system pressure) using the pressure difference to ensure that the catalyst mass content in the three-phase mixed liquid in the reaction tube is 13±5%.

[0055] The diameter of the tubular reaction tube in this embodiment is 50 mm, the height of the reaction section is 3500 mm, the flow rate of the raw material feed pump is 8.75 L / h, and the flow rate of the high-pressure circulation pump is 3.5 m 3 / h, the hydrogen flow rate at the reactor inlet is 1.5m 3 / h.

[0056] Compared with Example 1, Example 2 is different in that the catalyst is prepared by Preparation Example 2.

[0057] Compared with Example 1, Example 3 is different in that the catalyst is prepared by Preparation Example 3.

[0058] The difference between Comparative Example 1 and Example 1 is that the catalyst is prepared by Comparative Preparation Example 1.

[0059] The difference between Comparative Example 2 and Example 1 is that the catalyst is prepared by Comparative Preparation Example 2.

[0060] Compared with Example 1, Comparative Example 3 is different in that the catalyst is prepared by Comparative Preparation Example 3.

[0061] The difference between Comparative Example 4 and Example 1 is that the catalyst is prepared by Comparative Preparation Example 4.

[0062] Compared with Example 1, Comparative Example 5 is different in that the catalyst is prepared by Comparative Preparation Example 5.

[0063] Test Example 2 The methods in Examples 1-3 of the present invention and Comparative Examples 1-5 were evaluated. The results are shown in Table 2.

[0064] Table 2

[0065] As can be seen from the above table, the methods in Examples 1-3 of the present invention have high conversion rates of 2-methylglutaronitrile, and higher selectivities for 2-methylglutaronitrile and 3-methylpiperidine.

[0066] Test Example 3 After the catalysts prepared in Examples 1-3 of the present invention or Comparative Examples 1-5 were subjected to continuous catalytic reaction for 200 hours, the specific surface areas of the catalysts before and after reaction were measured. The results are shown in Table 3.

[0067] Table 3

[0068] It can be seen from the above table that after the catalysts in Examples 1-3 of the present invention continuously catalyze the reaction for 200 hours, the specific surface areas are not much different, indicating that their physical and chemical properties do not change much.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for producing methylpentanediamine and methylpiperidine by hydrogenating methylglutaronitrile, characterized in that: The steps include: (1) In the raw material tank, the mixed liquid of 2-methylglutaronitrile and hydrogen-soluble solvent is pressurized by a feed pump and heated by a preheater, and enters the lower feed pipe of the pipeline reactor together with the liquid-solid phase mixed material from the high-pressure circulation pump. The hydrogen from the hydrogen circulation machine and the fresh supplementary hydrogen are combined and enter the gas distributor at the bottom of the pipeline reactor. The hydrogen and the liquid-solid phase materials form a gas-liquid-solid three-phase material and undergo a catalytic hydrogenation reaction during the process of rising from the bottom of the pipeline reactor; (2) The gas-liquid-solid three-phase materials are separated into gas phase-liquid-solid phase at the upper part of the reactor, and the liquid-solid phase overflows into the high-pressure gas-liquid-solid phase separator for further gas phase separation; the separated hydrogen is combined and cooled and separated; and then returned to the bottom of the pipeline reactor by the hydrogen circulation machine; the liquid and solid phase materials at the bottom of the high-pressure gas-liquid-solid phase separator are returned to the lower part of the pipeline reactor by the high-pressure circulation pump; (3) The liquid phase produced in the middle of the high-pressure gas-liquid-solid phase separator is sent to the low-pressure liquid-solid phase separator after decompression. The liquid phase produced in the middle of the low-pressure liquid-solid phase separator enters the hydrogen-soluble solvent recovery tower. The hydrogen-soluble solvent recovered at the top of the tower is sent back to the raw material tank. The product methylpentanediamine and methylpiperidine mixed liquid at the bottom of the tower is sent to the product intermediate tank. (4) The catalyst separated by the low-pressure liquid-solid phase separator is recovered to the catalyst configuration system for online catalyst regeneration and replenishment.

2. The method according to claim 1, characterized in that: The mixed liquid in the raw material tank is prepared according to the mass ratio of 2-methylglutaronitrile to hydrogen-soluble solvent of 1.0-4.0:1.0; the hydrogen-soluble solvent is methanol or ethanol; the pressure is increased to 2.0-3.0 MPa by a feed pump; and the mixed liquid is preheated to 50-90° C. by a preheater.

3. The method according to claim 1, characterized in that: The mixed liquid of methylglutaronitrile and hydrogen-soluble solvent is pressurized by a feed pump and preheated by a preheater, and enters a liquid-solid material feed pipe at the bottom of a pipeline reactor together with liquid-solid materials from a high-pressure circulation pump, wherein the volume flow ratio of the liquid-solid materials from the high-pressure circulation pump to the mixed liquid of 2-methylglutaronitrile and hydrogen-soluble solvent from the feed pump is 300-600, and the residence time of the mixed liquid phase in the reaction tube is 5-15 seconds.

4. The method according to claim 1, characterized in that: The hydrogen from the hydrogen circulation machine and the fresh supplementary hydrogen merge into the gas distributor at the bottom of the pipeline reactor, wherein the diameter of a single hole on the distributor orifice plate is 1.0-2.0 mm and is evenly distributed; the volume flow ratio of the hydrogen in the standard state entering the bottom of the pipeline reactor to the liquid-solid phase material of the high-pressure circulation pump is 0.3-0.5:1.

0.

5. The method according to claim 1, characterized in that: The pipeline reactor is a sleeve-type empty tube bubbling reactor, wherein the inner tube is a reaction section, the outer tube is a water cooling section, the height of the reaction section is the length from the lower liquid-solid phase material feed pipe port to the upper liquid-solid phase overflow port, the diameter-to-height ratio of the pipeline reactor reaction section is 60-80, a gas distributor is arranged at the bottom and is a perforated plate type, the lower liquid-solid phase material feed pipe is arranged above the gas distributor, the reaction pressure of the pipeline reactor reaction section is 2.0-3.0 MPa; the reaction temperature is 50-90° C., the hydrogenation reaction of 2-methylglutaronitrile is an exothermic reaction, and the outer tube cooling section is used for water cooling to transfer heat, and the reaction temperature is controlled to be 50-90° C.

6. The method according to claim 1, characterized in that: The gas-liquid-solid three-phase material for catalytic hydrogenation reaction during the process of rising from the bottom of the reactor is: the gas phase is hydrogen, the solid phase is a catalyst, the catalyst is a modified nickel catalyst, and the liquid phase is a mixed liquid composed of 2-methylglutaronitrile, 2-methylpentanediamine, 3-methylpiperidine, hydrogenation by-products, alkaline auxiliary agents and hydrogen-soluble solvents. During the process of the gas-liquid-solid three-phase material rising from the bottom of the reactor, the solid phase catalyst accounts for 10-20% of the mass content of the three-phase mixed liquid; the alkaline auxiliary agent is sodium hydroxide or potassium hydroxide, and the proportion of the three-phase mixed liquid is 0.01-0.5% of the mass content.

7. The method according to claim 1, characterized in that: The gas-liquid-solid three-phase material is separated from the unreacted hydrogen at the top of the reactor and the high-pressure gas-liquid-solid phase separator, and enters the tube-type water cooler at the top of the pipeline reactor. After cooling, the temperature is 30-35°C, and the separated hydrogen-dissolving solvent is refluxed to the pipeline reactor. The unreacted hydrogen is returned to the bottom of the pipeline reactor by the hydrogen circulation machine and is supplemented with fresh hydrogen from the hydrogen supply station.

8. The method according to claim 1, characterized in that: The liquid-solid phase overflow at the top of the pipeline reactor enters the high-pressure gas-liquid-solid phase separator, and the high-pressure gas-liquid-solid phase separator is provided with a lateral cyclone guide pipe to promote the solid phase to settle at the bottom. The bottom is the liquid-solid phase material containing 10-15% catalyst, which is then returned to the lower feed port of the pipeline reactor by a high-pressure circulation pump.

9. The method according to claim 1, characterized in that: The liquid phase extracted from the middle of the high-pressure gas-liquid-solid phase separator is sent to the low-pressure liquid-solid phase separator after decompression, and the liquid-solid phase materials containing 1-3% catalyst enter the low-pressure liquid-solid phase separator provided with a lateral cyclone guide pipe. The operating pressure of the low-pressure liquid-solid phase separator is atmospheric pressure.

10. The method according to claim 1, characterized in that: The catalyst separated by the low-pressure liquid-solid phase separator is recovered to the catalyst configuration system; the catalyst configuration system is protected by nitrogen, and the recovered 1-3% catalyst and the supplemented fresh catalyst are regenerated by 20% sodium hydroxide alkaline washing. After regeneration, the catalyst is mixed with an appropriate hydrogen-soluble solvent and then fed into the reaction system by high-pressure nitrogen using the pressure difference. The pressure of the high-pressure nitrogen is 0.2-0.5Mpa higher than the pressure of the reaction system.

11. The method according to claim 1, characterized in that: The liquid phase extracted from the middle of the low-pressure liquid-solid phase separator enters the hydrogen-dissolving solvent recovery tower. The operating pressure of the recovery tower is atmospheric pressure. The cooling reflux temperature at the top of the recovery tower is 30-35° C., and the reflux ratio is 1-2. The reboiling temperature at the bottom of the recovery tower is 75-80° C., and the outlet material at the bottom of the recovery tower is a mixed liquid of 2-methylpentanediamine and 3-methylpiperidine, which is cooled to 30-35° C. and sent to the product intermediate tank.

Images