Integrated continuous self-suction paddle hydrogenation reaction and catalyst separation system and method

Abstract

The application discloses a highly integrated continuous self-suction paddle hydrogenation reaction and a system for separating hydrogenation product solution and catalyst and a method for hydrogenation reaction and separation of hydrogenation product solution and catalyst using the same. The system comprises a kettle reactor, and a metal membrane filtering assembly, a heat exchange assembly, a self-suction paddle stirrer located in the center of the kettle reactor, a feed distributor located at the upper part, a hydrogen distributor located at the lower part and a feed inlet arranged on the top shell of the kettle reactor are arranged in the interior of the kettle reactor. The self-suction paddle stirrer comprises multiple layers of paddles, at least one layer of the paddles is a self-suction paddle, and the opening of the self-suction paddle is communicated with the top space of the kettle reactor through a hollow stirring shaft.

Description

Technical Field

[0001] This invention relates to a highly integrated method and system for continuous self-priming paddle hydrogenation reaction and catalyst separation, specifically to a highly integrated system for continuous self-priming paddle hydrogenation reaction and separation of hydrogenation product solution and catalyst, and a method for using the same for hydrogenation reaction and separation of hydrogenation product solution and catalyst. Background Technology

[0002] HMDA is primarily produced through high-pressure catalytic hydrogenation of MDA. On one hand, HMDA can be reacted with sebacic acid or adipic acid to produce nylon. On the other hand, HMDA is a raw material for preparing a new generation of high-performance, anti-aging polyurethane—4,4'-dicyclohexylmethane diisocyanate. This type of isocyanate is suitable for preparing lightweight, stable polyurethane coatings and paints, with applications in electromechanical, shipbuilding, civil engineering, and textile industries. In recent years, its demand in domestic and international markets has been increasing year by year.

[0003] MDA hydrogenation is extremely difficult due to the stable large π bonds in the benzene ring. Destroying this structure to achieve hydrogenation of the benzene ring requires high-temperature, high-pressure reactors, and such reactions are generally carried out in batch or semi-continuous operations. The following is the MDA hydrogenation process: The first step of the MDA hydrogenation reaction yields a partially hydrogenated product, H6MDA, which is then further hydrogenated to obtain H... 12 MDA, which is the HMDA mentioned earlier.

[0004]

[0005] Moreover, the HMDA hydrogenation catalyst is a molecular sieve support, which has the characteristics of small particles and light weight. Traditional solid-liquid separation methods are difficult to solve the problems of effective separation and continuous recycling. At present, the batch or semi-continuous production process has a long production cycle, low efficiency and complicated operation; and the catalyst separation is cumbersome and has a low degree of automation.

[0006] Patent applications US2511028A, US2606924A, US3644522A, and US4394522A all describe batch or semi-continuous reaction processes. A supported ruthenium catalyst, co-catalyst, and solvent are added together to a high-pressure reactor, followed by the addition of a solvent containing dissolved raw materials. The reactor is sealed, pressurized to a set pressure, heated, and stirred. The product is filtered at room temperature and analyzed chromatographically. The same process can be employed using an Rh catalyst.

[0007] Patent application US2606924A uses alcohols as solvents and ruthenium oxide as a catalyst for continuous or semi-continuous hydrogenation of MDA. US3591635A uses isopropanol as a solvent for semi-continuous hydrogenation of MDA. Patent application US3856862A uses C1-C8 lower alkanols as solvents for hydrogenation, with primary and tertiary alcohols showing better results. Patent application US4394522A uses n-butyl ether with a mass fraction of 0-95% as a solvent to prepare MDA to a concentration of 5-50 wt% for hydrogenation. Patent application US4754070A uses THF as a solvent. Patent application US2606928A uses anhydrous dioxane as a solvent for hydrogenation of MDA, generating alicyclic diamine compounds at 130-180°C and 300 atm.

[0008] It is evident that most current MDA catalytic hydrogenation technologies employ supported noble metal catalysts, with rhodium and ruthenium being the most common. MDA is dissolved in a suitable solvent, with alcohols and ethers being the most common solvents, to prepare a solution of a certain concentration, typically between 5 wt% and 50 wt%. The reaction is carried out in a stirred tank reactor under high temperature and high pressure in a batch or semi-continuous manner, with temperatures typically between 150°C and 250°C and pressures typically between 10 MPa and 15 MPa.

[0009] Zhi Dingwei et al. proposed a continuous preparation method for 4,4′-diaminodicyclohexylmethane in CN112851522A. This method utilizes a jet circulation reactor and a Y-type microchannel reactor, employing a supported bimetallic ruthenium-rhodium catalyst to achieve the hydrogenation reaction of MDA, yielding HMDA product. However, the method suffers from several drawbacks. The external circulation pump used to transport the gas-liquid-solid three-phase materials under high temperature and pressure conditions is expensive, resulting in high energy consumption due to the large flow rate, numerous external high-temperature and high-pressure equipment, complex process control, and multiple potential catalyst and material leakage points.

[0010] Furthermore, most existing literature and patent disclosures are from foreign sources or foreign applicants, and they mainly concern the development and optimization of catalysts, while there are few reports on related equipment and processes. Therefore, in order to develop our own continuous production technology, it is necessary to conduct research on the localization of process routes. Summary of the Invention

[0011] This invention addresses the shortcomings of existing technologies. The purpose of this invention is to provide a highly integrated system and method for continuous self-priming paddle hydrogenation reaction and catalyst separation in slurry bed reactor processes.

[0012] According to the system and method described in this invention, HMDA with low anti-anti content is prepared, and the product has stable performance, achieving 100% MDA hydrogenation conversion, HMDA yield of over 98%, and anti-anti content of 14wt% to 18wt% (compared to 20wt% to 22wt% in the prior art).

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] This invention provides a highly integrated continuous self-priming paddle hydrogenation reaction and catalyst separation system, comprising: a batch reactor, inside which are arranged: a metal membrane filter assembly, a heat exchange assembly, a self-priming paddle agitator located in the center of the batch reactor, a feed distributor located at the top, a hydrogen distributor located at the bottom, and a feed inlet located on the top shell of the batch reactor, wherein the self-priming paddle agitator comprises multiple layers of blades, and at least one layer of blades is a self-priming paddle, and the opening of the self-priming paddle communicates with the top space of the batch reactor through a hollow stirring shaft.

[0015] Preferably, the metal membrane filter assembly is arranged in a cylindrical flow guide tube shape; more preferably, the metal membrane filter assembly is a plurality of metal membrane filter assemblies.

[0016] Preferably, the metal membrane filtration assembly includes multiple tubular metal membrane filter elements for microfiltration or ultrafiltration.

[0017] Preferably, the tubular metal membrane filter elements are arranged in an equilateral triangle.

[0018] This tubular metal membrane filter element includes an inner cavity and a filter layer. The filter layer is made of metal, with a preferred thickness of 1–10 mm. The outer diameter of the filter element is Φ10–150 mm, and the length is Φ500–5000 mm. To facilitate manual assembly and disassembly, the filter element can be made in multiple sections.

[0019] Preferably, the filtration accuracy of the metal membrane filter assembly is 0.1 to 30 μm; the tubular metal membrane filter element has a backwash pressure differential resistance of 0.1 to 3 MPa.

[0020] Preferably, the filter layer material of the tubular metal membrane filter element can be stainless steel, nickel, bronze, high-temperature alloy, Hastelloy, titanium, Monel alloy, etc., and is formed by sintering filter screens or metal powder. It features high strength, resistance to high-pressure backwashing, simple and thorough cleaning, stable chemical properties, and long service life.

[0021] Preferably, the self-priming paddle is located at the middle of the height of the batch reactor.

[0022] Preferably, the hollow stirring shaft of the self-priming impeller is a tubular structure sealed at both ends, and the opening of the self-priming impeller is connected to the top space of the reactor through the hollow stirring shaft.

[0023] Preferably, the self-priming impeller is a combination of multiple impellers. Based on the size and length-to-diameter ratio of the reactor, CFD simulation calculations show that the self-priming impeller is a combination of three or four impellers.

[0024] Preferably, the self-priming impeller agitator is a three-layer agitator combination, with a turbine impeller at the bottom, a self-priming impeller in the middle, and an axial flow impeller at the top.

[0025] The lower-layer turbine propeller disperses the fresh hydrogen introduced by the hydrogen distributor into bubbles, which then mix with the liquid phase. The middle-layer self-priming propeller draws hydrogen from the reactor's gas phase space through the intake port at the top of the hollow stirring shaft, then ejects and disperses it to mix with the liquid phase. The upper-layer axial-flow propeller creates a high-flow-rate axial circulation within the system, promoting uniform hydrogen distribution and temperature homogenization throughout the reactor space.

[0026] Preferably, the self-priming impeller agitator is a four-layer agitator combination, comprising, in sequence: a lower turbine impeller, a middle self-priming impeller, another turbine impeller between the turbine impeller and the self-priming impeller, and an upper axial flow impeller.

[0027] Preferably, the heat exchange assembly includes a heating assembly and a cooling assembly; more preferably, the heating assembly is a heating coil and the cooling assembly is a cooling coil.

[0028] Preferably, the feed distributor is a circular tube structure, wherein the circular tube has small holes with downward openings evenly distributed.

[0029] Preferably, the hydrogen distributor is a circular tube structure, wherein the circular tube has small holes with downward openings evenly distributed throughout.

[0030] Preferably, the metal membrane filter assembly, the heat exchange assembly, the feed distributor, and the hydrogen distributor are each connected to the outside via pipelines.

[0031] Preferably, the metal membrane filter assembly, the self-priming impeller agitator located in the center of the reactor, the heat exchange assembly, the feed distributor located at the top, and the hydrogen distributor located at the bottom are fixed in the reactor by fixed supports.

[0032] According to a second aspect of the present invention, a method for separating a hydrogenation reaction from a catalyst is provided, the hydrogenation reaction being carried out in a system according to the present invention, and comprising the following steps:

[0033] 1) Add catalyst through the feed inlet, add raw material solution through feed distributor, introduce hydrogen through hydrogen distributor, and heat up under the stirring of self-priming paddle agitator to hydrogenate raw material and hydrogen through hydrogenation reaction to obtain hydrogenated product.

[0034] 2) The reactants are separated into a solution containing hydrogenation products by passing them through the metal membrane filtration assembly, while the catalyst remains in the batch reactor to continue participating in the reaction;

[0035] 3) The solution from which the hydrogenation products are separated in step 2) is directly transported to the subsequent evaporation and desolventization process.

[0036] Preferably, the raw material is MDA (4,4'-diaminodiphenylmethane), and the hydrogenation product is HMDA (4,4'-diaminodicyclohexylmethane).

[0037] Preferably, the hydrogenation reaction conditions in step 1) are: reaction temperature 130-200℃, reaction pressure 5-10 MPaG.

[0038] Preferably, the solvent in the solution of the raw material is an alcohol or ether selected from C2 to C6, more preferably selected from one or more of ethanol, isopropanol, sec-butanol, tert-butanol, n-butyl ether, tert-butyl ether and THF.

[0039] Preferably, the mass concentration of the raw material solution is 20wt% to 80wt%, and the hydrogen purity is 99wt% or higher.

[0040] Preferably, the catalyst is a molecular sieve-supported noble metal catalyst. Preferably, the mass fraction of the catalyst in the reaction solution is 0.05 wt% to 5 wt%, more preferably 0.2 wt% to 4 wt%.

[0041] The molecular sieve-supported noble metal catalyst is a conventionally used catalyst in the art; for example, a molecular sieve-supported bimetallic ruthenium-rhodium catalyst can be used.

[0042] Preferably, after the solution containing hydrogenated products is separated from the metal membrane filter assembly, the metal membrane filter assembly is backwashed using a solvent.

[0043] Preferably, the backwash pressure difference is 0.1–3 MPa, the backwash time is 1–30 s, and the backwash cycle is 1–30 min.

[0044] Preferably, hydrogen is initially and evenly distributed in the reaction system through a distributor, and then the gas content in the system is maintained at 2 vol% to 10 vol% by a self-priming paddle stirrer to meet the mass and heat transfer requirements of the system.

[0045] Preferably, the rotational speed of the self-priming impeller is 120–300 rpm.

[0046] In step 1) of this invention, the reaction system is heated or the heat of reaction is removed by a heat exchange component.

[0047] Preferably, the reaction system is heated by a heating coil at the beginning of the reaction.

[0048] Preferably, the heating medium in the heating coil is steam.

[0049] Preferably, the heat of reaction is removed by a cooling coil.

[0050] Preferably, the heat transfer medium in the cooling coil is hot water, with an inlet and outlet water temperature of 75-95°C, which is then converted by a hot water type lithium bromide unit to produce low-temperature water of 7-10°C.

[0051] In step 2), the metal membrane filter assembly can be arranged in a flow guide tube pattern, with the membrane tube filter elements arranged in an equilateral triangle to reduce flow dead zones and make full use of the radial and axial high-flow circulation brought about by the high-speed rotation of the stirring paddle. This ensures that the average flow velocity of the reactants on the surface of the metal membrane filter element is not less than 2.5 m / s, promoting catalyst renewal on the surface of the filter element at each angle and preventing catalyst deposition.

[0052] Preferably, in step 3), the solution from which the hydrogenation product is separated is directly sent to the subsequent evaporation and desolventizing process, without the need for further filtration to remove the catalyst.

[0053] Preferably, the content of the anti-anti monomer of HMDA prepared by the method according to the present invention is less than 18 wt%, more preferably 14 wt% to 18 wt%.

[0054] The highly integrated continuous self-priming paddle hydrogenation reaction and catalyst separation method and system according to the present invention have the following advantages:

[0055] The reactor uses a self-priming paddle agitator to increase the hydrogen content in the system and increase the mass transfer coefficient. The reactants are filtered through the built-in metal membrane filter assembly, which traps the catalyst in the reactor to continue the reaction. The filtrate is sent to the subsequent process.

[0056] ① This continuous hydrogenation system has a high degree of integration and automation. It integrates a self-priming impeller agitator, a gas-liquid phase feed distributor, heat exchange components (heating coils and / or heat transfer coils), and a built-in metal membrane filter assembly. The metal membrane filter assembly is rationally distributed and also acts as a flow guide. Combined with the high-speed rotating self-priming impeller (middle layer) and other layers of agitators, it forms a large-flow axial and radial circulation field. The surface flow rate is fast, and the catalyst is not easy to deposit on the surface of the metal membrane filter element. At the same time, fresh solvent is used to backwash the metal membrane filter assembly online, which washes away the filter cake layer on the surface of the filter assembly and the catalyst deposited inside the filter element in time, extending the life of the metal membrane filter assembly and meeting the requirements of continuous long-cycle operation. It has broad prospects for industrial application.

[0057] ② Compared with the external circulation cross-flow filter solution, the present invention does not require a high-pressure pump and external circulation equipment, resulting in lower energy consumption and investment costs;

[0058] ③ Compared to batch reactor hydrogenation, the equipment of this invention is smaller in size and the process is simpler. A production unit of 50,000 t / a only requires two 50m³ units. 3 The number of reactors is about one-fifth that of batch reactor hydrogenation schemes, and the number of supporting high-pressure valves and instruments is reduced, resulting in significant savings in equipment investment and operating costs.

[0059] ④ The heat of reaction is removed through the hot water medium in the cooling coil, and then converted by the hot water type lithium bromide unit to produce low-temperature water of 7-10℃, which has high energy utilization and reduces carbon emissions. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of a highly integrated continuous self-priming paddle hydrogenation reaction and catalyst separation system according to one embodiment of the present invention;

[0061] Figure 2 This is a schematic diagram of the distribution of a metal membrane filter assembly according to an embodiment of the present invention;

[0062] Figure 3 This is a schematic diagram of the filter element arrangement angle of a metal membrane filter assembly according to an embodiment of the present invention;

[0063] Figure 4 , Figure 5 and Figure 6 These are schematic diagrams showing the distribution of metal membrane filter components in Comparative Examples 2 to 4.

[0064] Figure Labels

[0065] 1-Stirred reactor; 2-Metal membrane filter assembly; 3-Filtrate outlet; 4-Backwash port; 5-Self-priming impeller; 6-Upper impeller; 7-Middle impeller (self-priming impeller); 8-Lower impeller; 9-Bottom support of the impeller shaft; 10-Hydrogen inlet; 11-Hydrogen distributor; 12-Raw material inlet; 13-Feed distributor; 14-Feed inlet; 15-Heat transfer medium inlet; 16-Heat transfer medium outlet; 17-Heating medium inlet; 18-Heating medium outlet; 19-Cooling coil; 20-Heating coil; 21-Coil support structure; 22-Metal membrane filter assembly mounting bracket; 23-Self-priming impeller hydrogen intake port. Detailed Implementation

[0066] The present invention will be further illustrated by specific embodiments below. It should be noted that the embodiments below are for illustrative purposes only, and the content of the present invention is not limited thereto.

[0067] like Figure 1 As shown, the highly integrated continuous self-priming paddle hydrogenation reaction and catalyst separation system according to the present invention includes: a batch reactor 1, inside which are arranged: a metal membrane filter assembly 2, a self-priming paddle agitator 5 located in the center of the batch reactor 1, a heat exchange assembly (including a cooling coil 19 and a heating coil 20), a feed distributor 13 located at the top, a hydrogen distributor 11 located at the bottom, and a feed inlet 14 located on the top shell of the batch reactor 1. The self-priming paddle agitator 5 includes three layers of blades: a lower turbine blade 8, a middle self-priming paddle 7, and an upper axial flow blade 6. The hollow agitator shaft of the self-priming paddle agitator 5 is a tubular structure sealed at both ends. A self-priming paddle hydrogen inlet 23 is provided on the hollow agitator shaft near the top of the batch reactor 1, and this self-priming paddle hydrogen inlet 23 communicates with the opening of the self-priming paddle 7 through the hollow agitator shaft. A hollow agitator shaft bottom support 9 is provided at the bottom of the batch reactor 1 for fixing the hollow agitator shaft. A hydrogen distributor 11 is disposed below the turbine propeller 8. The hydrogen distributor 11 is a circular tube structure with small holes evenly distributed on the tube, facing downwards. The hydrogen distributor 11 is connected to a hydrogen inlet 10 disposed outside the batch reactor 1 via a pipeline. The hydrogen inlet 10 is connected to a hydrogen storage tank (not shown) via a pipeline to supply hydrogen.

[0068] A feed distributor 13 is installed at the top of the batch reactor 1. It is a circular annular tube with small holes evenly distributed around it, facing downwards. The feed distributor 13 is connected to a raw material inlet 12 located outside the batch reactor 1 via a pipeline. The raw material inlet 12 is connected to a raw material storage tank (not shown) via a pipeline to supply the reaction raw materials.

[0069] Inside the stirred tank reactor 1, a metal membrane filter assembly 2 is installed at a distance of 3 / 4 of the inner diameter from the stirring shaft. For example... Figure 2 As shown, the metal membrane filter assembly 2 is arranged in a cylindrical structure, serving as a flow guide. The metal membrane filter assembly includes multiple microfiltration tubular metal membrane filter elements. Figure 3As shown, these tubular metal membrane filter elements are arranged in an equilateral triangle, thereby reducing flow dead zones and fully utilizing the large radial and axial flow circulation brought about by the high-speed rotation of the agitator. This ensures that the average flow velocity on the surface of the metal membrane filter element is not less than 2.5 m / s, promoting catalyst renewal on the surface of the filter element at all angles and preventing catalyst deposition. The tubular metal membrane filter element includes an inner cavity and a filter layer. The filter layer is made of stainless steel with a thickness of 1–10 mm and an outer diameter of Φ10–150 mm; the filter element length is Φ500–5000 mm. The metal membrane filter assembly 2 is connected to the filtrate outlet 3 and backwash port 4 outside the reactor 1 via pipelines. Valves are installed on the pipelines of the filtrate outlet 3 and backwash port 4. When discharging the filtrate, the valve of the backwash port 4 is closed, allowing the filtrate to be discharged through the filtrate outlet 3. When backwashing, the filtrate outlet 3 is closed, allowing the backwash solvent to enter the metal membrane filter assembly 2 for rinsing. In addition, the metal membrane filter assembly 2 is fixed to the batch reactor 1 by the metal membrane filter assembly support 22.

[0070] The heat exchange assembly includes a cooling coil 19 and a heating coil 20 disposed near the side wall of the batch reactor 1, which are used to cool and heat the reaction system inside the batch reactor 1, respectively. The cooling coil 19 and the heating coil 20 are fixed to the batch reactor 1 by coil supports 21. The cooling coil 19 is connected via pipes to a heat transfer medium inlet 15 and a heat transfer medium outlet 16 located outside the batch reactor 1, respectively, to provide or discharge the heat transfer medium. The heating coil 20 is connected via pipes to a heating medium inlet 17 and a heating medium outlet 18 located outside the batch reactor 1, respectively, to provide or discharge the heating medium.

[0071] The feed inlet 14 located on the top shell of the batch reactor 1 is used to feed the catalyst or optional other raw materials.

[0072] (1) The design pressure of the batch reactor is 9-13 MPaG, the design temperature is 200-300℃, and the reactor volume is 2-100 m³. 3 The self-priming paddle agitator rotates at 120–280 rpm.

[0073] (2) The batch reactor 1 first undergoes nitrogen and hydrogen purging to test the airtightness of the system. After the airtightness test is passed, the MDA raw material and solvent are pre-mixed into a raw material solution in an external mixing tank according to the required ratio. The raw material solution is then added sequentially through the raw material inlet 12 to a level of 70% as the bottom material. The solvent can be alcohols such as ethanol, isopropanol, sec-butanol, tert-butanol, etc., or ethers such as n-butyl ether, tert-butyl ether, THF, etc. The catalyst, such as a molecular sieve-supported ruthenium-rhodium bimetallic catalyst, is prepared in advance with the solvent to form a dispersion with a catalyst content of 20wt% to 40wt%. This dispersion is added to the reactor through the feed inlet 14, controlling the catalyst content in the reactor to be 0.05wt% to 5wt%. Then, steam (heating medium) is introduced through the heating coil 20 to preheat the bottom material to 100 to 120°C. The self-priming impeller 5 is turned on, and the self-priming impeller 7 rotates at high speed to produce... The negative pressure generated continuously draws in and redisperses hydrogen from the gas phase space through the self-priming impeller hydrogen inlet 23, maintaining a gas content of 2-10% in the liquid phase space of the reactor. Combined with the upper and lower stirring impellers 6 and 8, a high-flow-rate axial-radial circulation field is maintained. Hydrogen is slowly introduced through the hydrogen inlet 10 and hydrogen distributor 11 to the reaction pressure. After initial distribution through the hydrogen distributor 11 and observation of the hydrogen absorption point, steam heating is stopped, and cooling water is introduced through the heat transfer medium inlet 15 to control the temperature, maintaining a reaction temperature of 130-200℃ and a reaction pressure of 5-10 MPaG. After 2-3 hours of reaction, samples are taken for analysis. If the raw material is completely converted into hydrogenated products, the raw material solution is continuously added through the raw material inlet 12, while the hydrogenated product solution is continuously collected through the filtrate outlet. The catalyst is retained in the reactor 1 by the metal membrane filter assembly 2 and continues to participate in the reaction. During operation, each group of metal membrane filter assemblies 2 is backwashed alternately through the backwash port 4 to prevent catalyst deposition on the surface and inside of the filter element, extending the service life of the metal membrane filter assembly. When the pressure difference between the inside and outside of the metal membrane filter module is greater than 0.5 MPaG and the required flow rate of product still cannot be extracted, the metal membrane filter module is judged to be blocked, the reaction ends, and the total number of continuous operation cycles is recorded.

[0074] The embodiments will use the process of preparing HMDA from MDA through hydrogenation reaction as an example to illustrate the highly integrated continuous self-priming paddle hydrogenation reaction and catalyst separation method and system according to the present invention.

[0075] Example 1

[0076] In an inert atmosphere, the molecular sieve-supported bimetallic ruthenium-rhodium catalyst was prepared into a 20 wt% dispersion using a solvent for later use.

[0077] like Figure 1As shown, MDA raw materials and solvents are continuously added through raw material inlet 12. The catalyst dispersion prepared above is added through feed inlet 14, controlling the catalyst content in the reactor to 0.5 wt%. Hydrogen is introduced through hydrogen inlet 10 and initially distributed through hydrogen distributor 11. The stirring speed is 150 rpm. The gas content in the liquid phase space of the reactor is maintained at 2 vol% by the self-priming impeller 7. In addition, the upper layer impeller 6 and the lower layer impeller 8 jointly maintain a large flow rate circulation in the axial and radial directions. The reactor volume is 20 m³. 3 MDA solution feed flow rate 2m 3 The reaction was carried out at a rate of / hr, with isopropanol as the solvent and an MDA concentration of 20 wt%. The hydrogen flow rate was controlled by maintaining a stable reaction pressure of 5 MPaG, and the reaction temperature was 130°C. The reactor's built-in metal membrane filter assembly had a filtration accuracy of 0.1 μm. A schematic diagram of the metal membrane filter assembly distribution and filter element arrangement angles can be found in [reference needed]. Figure 2 and Figure 3 The metal membrane filter assembly, distributed in this manner, also functions as a flow guide, ensuring more uniform high-flow-rate circulation within the reactor. The average flow velocity on the surface of the metal membrane filter element is approximately 2.5 m / s. After hydrogenation, the HMDA solution is continuously collected through the filtrate outlet 3, while the catalyst is retained within the reactor by the metal membrane filter assembly 2 to continue participating in the reaction. During operation, isopropanol, the reaction solvent, is used to backwash each group of metal membrane filter assemblies 2 alternately through the backwash port 4. The backwash pressure is 5.2 MPaG, the backwash time is 8 seconds, and the backwash cycle is 10 minutes. Under these process conditions, after a 3-month operating period, the MDA hydrogenation conversion rate is 95%, the HMDA yield reaches 93%, and the content of the reactant is 14 wt%.

[0078] Example 2

[0079] In an inert atmosphere, the molecular sieve-supported bimetallic ruthenium-rhodium catalyst was prepared into a 20 wt% dispersion using a solvent for later use.

[0080] like Figure 1 As shown, MDA raw materials and solvents are continuously added through raw material inlet 12. The catalyst dispersion prepared above is added through feed inlet 14, controlling the catalyst content in the reactor to 1 wt%. Hydrogen is introduced through hydrogen inlet 10 and initially distributed through hydrogen distributor 11. The stirring speed is 200 rpm. The gas content in the liquid phase space of the reactor is maintained at 5 vol% by the self-priming impeller 7. In addition, the upper layer impeller 6 and the lower layer impeller 8 jointly maintain a large flow rate circulation in the axial and radial directions. The reactor volume is 40 m³. 3 The MDA solution feed flow rate is 2.7 m³ / h. 3 The reaction was carried out at a rate of / hr, with THF as the solvent and 40wt% MDA concentration. Hydrogen flow was controlled by maintaining a stable reaction pressure of 7 MPaG, and the reaction temperature was 150℃. The reactor's built-in metal membrane filter assembly had a filtration accuracy of 10 μm. A schematic diagram of the metal membrane filter assembly distribution and filter element arrangement angles can be found in [reference needed]. Figure 2 and Figure 3 This distribution of the metal membrane filter assembly also functions as a flow guide, making the high-flow-rate circulation inside the reactor more uniform. The average flow velocity on the surface of the metal membrane filter element is approximately 2.8 m / s. After hydrogenation, the HMDA solution is continuously collected through the filtrate outlet 3, while the catalyst is retained in the reactor by the metal membrane filter assembly 2 to continue participating in the reaction. During operation, the reaction solvent THF is used to backwash each group of metal membrane filter assemblies 2 alternately through the backwash port 4. The backwash pressure is 7.2 MPaG, the backwash time is 15 s, and the backwash cycle is 20 min. Under the above process conditions, after 10 months of operation, the MDA hydrogenation conversion rate is 100%, the HMDA yield reaches 96%, and the content of the reactants is 16 wt%.

[0081] Example 3

[0082] In an inert atmosphere, the molecular sieve-supported bimetallic ruthenium-rhodium catalyst was prepared into a 20 wt% dispersion using a solvent for later use.

[0083] like Figure 1 As shown, MDA raw materials and solvents are continuously added through raw material inlet 12. The catalyst dispersion prepared above is added through feed inlet 14, controlling the catalyst content in the reactor to 1.5 wt%. Hydrogen is introduced through hydrogen inlet 10 and initially distributed through hydrogen distributor 11. The stirring speed is 280 rpm. The gas content in the liquid phase space of the reactor is maintained at 10 vol% by the self-priming impeller 7. In addition, the upper layer impeller 6 and the lower layer impeller 8 jointly maintain a large flow rate circulation in the axial and radial directions. The reactor volume is 60 m³. 3 The MDA solution feed flow rate is 5.6 m³ / h. 3 The reaction was carried out at a rate of / hr, with tert-butyl ether as the solvent and an MDA concentration of 70 wt%. The hydrogen flow rate was controlled by maintaining a stable reaction pressure of 9 MPaG, and the reaction temperature was 180℃. The reactor's built-in metal membrane filter assembly had a filtration accuracy of 30 μm. A schematic diagram of the metal membrane filter assembly distribution and filter element arrangement angles can be found in [reference needed]. Figure 2 and Figure 3 This distribution of the metal membrane filter assembly also functions as a flow guide, making the high-flow-rate circulation inside the reactor more uniform. The average flow velocity on the surface of the metal membrane filter element is approximately 3.2 m / s. After hydrogenation, the HMDA solution is continuously collected through the filtrate outlet 3, while the catalyst is retained in the reactor by the metal membrane filter assembly 2 to continue participating in the reaction. During operation, the reaction solvent tert-butyl ether is used to backwash each group of metal membrane filter assemblies 2 alternately through the backwash port 4. The backwash pressure is 9.2 MPaG, the backwash time is 20 s, and the backwash cycle is 30 min. Under the above process conditions, the operation cycle is 18 months, the MDA hydrogenation conversion rate is 100%, the HMDA yield reaches 98%, and the content of the reactant is 18 wt%.

[0084] Comparative Example 1

[0085] The steps and operations are the same as in Example 3, except that the middle layer agitator 7 does not use a self-priming impeller, but a regular turbine impeller.

[0086] By maintaining a gas holdup of 1.3 vol in the reactor liquid phase space using turbine propeller 7, and an average flow velocity of approximately 0.8 m / s on the surface of the metal membrane filter element, under the above process conditions, the operating cycle is 1 month, the MDA hydrogenation conversion rate is 80%, the HMDA yield reaches 78%, and the content of the anti-antibody is 22 wt%.

[0087] Comparative Example 2

[0088] The steps and operations are the same as in Example 3. A schematic diagram of the metal membrane filter assembly distribution is shown below. Figure 4 .

[0089] See the schematic diagram of the metal membrane filter assembly distribution. Figure 4 With this distribution, the metal membrane filter assembly does not have the function of a flow guide tube. The average flow velocity on the surface of the metal membrane filter element is about 2m / s. Under the above process conditions, the operating cycle is 6 months, the MDA hydrogenation conversion rate is 100%, the HMDA yield reaches 98%, and the content of the anti-antibody is 20wt%.

[0090] Comparative Example 3

[0091] The steps and operations are the same as in Example 3. A schematic diagram of the metal membrane filter assembly distribution is shown below. Figure 5 .

[0092] See the schematic diagram of the metal membrane filter assembly distribution. Figure 5 According to this distribution, the metal membrane filter assembly does not have the function of a flow guide tube. The average flow velocity on the surface of the metal membrane filter element is about 1.8 m / s. Under the above process conditions, the operating cycle is 5 months, the MDA hydrogenation conversion rate is 100%, the HMDA yield reaches 98%, and the content of the anti-antibody is 21 wt%.

[0093] Comparative Example 4

[0094] The steps and operations are the same as in Example 3. A schematic diagram of the metal membrane filter assembly distribution is shown below. Figure 6 .

[0095] See the schematic diagram of the metal membrane filter assembly distribution. Figure 5 According to this distribution, the metal membrane filter assembly does not have the function of a flow guide tube. The average flow velocity on the surface of the metal membrane filter element is about 1.8 m / s. Under the above process conditions, the operating cycle is 7 months, the MDA hydrogenation conversion rate is 100%, the HMDA yield reaches 98%, and the content of the reverse is 20 wt%.

[0096] Table 1. Summary of hydrogenation process conditions and results for the examples and comparative examples.

[0097]

[0098] IE1 to IE3 represent Examples 1 to 3, respectively, and CE1 to CE4 represent Comparative Examples 1 to 4, respectively.

Claims

1. A highly integrated system for the continuous self-priming paddle MDA hydrogenation reaction to prepare HMDA and the separation of the catalyst, comprising: The batch reactor includes: a metal membrane filter assembly, a heat exchange assembly, a self-priming paddle agitator located in the center of the batch reactor, a feed distributor located at the top, a hydrogen distributor located at the bottom, and a catalyst inlet located on the top shell of the batch reactor. The self-priming impeller agitator is a three-layer agitator combination type, with a turbine impeller at the bottom, a self-priming impeller in the middle, and an axial flow impeller at the top. Alternatively, the self-priming impeller agitator is a four-layer agitator combination, comprising, in sequence: a lower turbine impeller, a middle self-priming impeller, another turbine impeller between the turbine impeller and the self-priming impeller, and an upper axial flow impeller. The opening of the self-priming paddle is connected to the top space of the batch reactor through a hollow stirring shaft. The metal membrane filter assembly consists of multiple sets of metal membrane filter assemblies; The metal membrane filter assembly is arranged in a cylindrical flow guide tube form; The metal membrane filtration assembly includes multiple tubular metal membrane filter elements for microfiltration or ultrafiltration. The tubular metal membrane filter elements are arranged in an equilateral triangle; The tubular metal membrane filter element includes an inner cavity and a filter layer, the filter layer being made of metal. The feed distributor is a circular tubular structure, wherein the circular tubular tube is evenly distributed with small holes facing downwards. The hydrogen distributor is a circular tube structure, wherein the circular tube is evenly distributed with small holes facing downwards.

2. The system according to claim 1, wherein, The filter layer thickness is 1~10mm, the filter element outer diameter is Φ10~150mm, and the filter element length is 500~5000mm. And / or, the filtration accuracy of the metal membrane filter assembly is 0.1~30μm; the tubular metal membrane filter element has a backwash pressure differential resistance of 0.1~3MPa; And / or, the filter layer material of the tubular metal membrane filter element is selected from stainless steel, nickel, bronze, Hastelloy, titanium and Monel alloy.

3. The system according to claim 1, wherein, The self-priming paddle is located at the middle of the height of the batch reactor. The hollow stirring shaft of the self-priming impeller is a tubular structure sealed at both ends.

4. The system according to any one of claims 1 to 3, wherein, The heat exchange assembly includes a heating assembly and a cooling assembly.

5. The system according to claim 4, wherein, The heating component is a heating coil, and the cooling component is a cooling coil.

6. The system according to any one of claims 1 to 3, wherein, The metal membrane filter assembly, the heat exchange assembly, the feed distributor, and the hydrogen distributor are each connected to the outside via pipelines; And / or, the metal membrane filter assembly, the self-priming paddle agitator, the heat exchange assembly, the feed distributor, and the hydrogen distributor are respectively fixed in the batch reactor by fixed brackets.

7. A method for preparing HMDA from MDA hydrogenation reaction and separating the catalyst, wherein the method for preparing HMDA from MDA hydrogenation reaction and separating the catalyst is carried out in the system according to any one of claims 1 to 6, the method comprising the following steps: 1) Add catalyst through the feed inlet, add raw material solution through the feed distributor, introduce hydrogen through the hydrogen distributor, and heat up under the stirring of the self-priming paddle agitator to hydrogenate the raw material and hydrogen through a hydrogenation reaction to obtain hydrogenated product. 2) The reactants are separated into a solution containing hydrogenation products by the metal membrane filtration assembly, while the catalyst remains in the batch reactor to continue participating in the reaction; 3) The solution from which the hydrogenation product is separated in step 2) is directly transported to the subsequent evaporation and desolventization process.

8. The method according to claim 7, wherein, The raw material is 4,4'-diaminodiphenylmethane, and the hydrogenation product is 4,4'-diaminodicyclohexylmethane. The hydrogenation reaction conditions in step 1) are: reaction temperature 130~200℃, reaction pressure 5~10MPaG.

9. The method according to claim 7, wherein, The solvent in the solution of the raw material is an alcohol or ether selected from C2 to C6.

10. The method according to claim 7, wherein, The mass concentration of the raw material solution is 20wt% to 80wt%, and the hydrogen purity is above 99wt%.

11. The method according to claim 8, wherein, The content of the anti-anti derivative of the hydrogenation product 4,4'-diaminodicyclohexylmethane is less than 18 wt%.

12. The method according to claim 11, wherein, The content of the trans-trans of the hydrogenation product 4,4'-diaminodicyclohexylmethane is 14wt% to 18wt%.

13. The method according to claim 9, wherein, The solvent in the solution of the raw material is selected from one or more of ethanol, isopropanol, sec-butanol, tert-butanol, n-butyl ether, tert-butyl ether and THF.

14. The method according to claim 7, wherein, The catalyst is a molecular sieve-supported noble metal catalyst.

15. The method according to claim 7, wherein, The catalyst has a mass fraction of 0.05 wt% to 5 wt% in the reaction solution.

16. The method according to claim 15, wherein, The mass fraction of the catalyst in the reaction solution is 0.2wt%~4wt%.

17. The method of claim 14, wherein, The molecular sieve-supported noble metal catalyst is a molecular sieve-supported bimetallic ruthenium-rhodium catalyst.

18. The method according to claim 7, wherein, The average flow velocity of the reactants on the surface of the metal membrane filter element is not less than 2.5 m / s.

19. The method according to claim 7, wherein, After the solution containing the hydrogenated product is separated from the metal membrane filter assembly, the metal membrane filter assembly is backwashed with a solvent. The backwashing pressure difference is 0.1~3MPa, the backwashing time is 1~30 s, and the backwashing cycle is 1~30 min.

20. The method according to claim 7 or 8, wherein, Hydrogen gas is initially and evenly distributed in the reaction system through a distributor, and then the gas content in the system is maintained at 2 vol% to 10 vol% by a self-priming paddle stirrer. And / or, the rotational speed of the self-priming paddle agitator is 120~300 rpm.

21. The method according to claim 7 or 8, wherein, In step 1), the reaction system is heated or the heat of reaction is removed by the heat exchange component. At the beginning stage of the reaction, the reaction system is heated by the heating coil, and the heating medium in the heating coil is steam.

22. The method according to claim 21, wherein, The heat of reaction is removed by a cooling coil, in which hot water is used as the heat transfer medium. The inlet and outlet water temperatures are 75–95°C. The water is then converted by a hot water-type lithium bromide unit to produce low-temperature water at 7–10°C.

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