Method and device for preparing HTDA through DNT one-step hydrogenation based on TDA solvent

Abstract

The invention discloses a method and a device for preparing HTDA through DNT one-step hydrogenation based on a TDA solvent, and belongs to the technical field of catalytic reaction. The method comprises the steps of pretreatment of reaction raw materials, catalytic hydrogenation, material circulation and continuous production. According to the method disclosed by the invention, the conversion rate of DNT and the selectivity of the target product HTDA are improved, the conversion rate of DNT and the selectivity of the target product HTDA can be respectively 100% and 90% after continuous production for 24 hours, the problem of separation of the product and the solvent is not involved, the production reaction process of the HTDA is shortened, and the production efficiency and the resource utilization rate are improved.

Description

Technical Field

[0001] This invention relates to the field of catalysts, and more specifically to a method and apparatus for one-step hydrogenation of DNT to HTDA based on TDA solvent. Background Technology

[0002] Currently, the global total production capacity of toluene diisocyanate (TDI) is 3.345 million tons, while my country's TDI production capacity is approximately 1.46 million tons. TDI is mainly used in the production of polyurethane materials. Because TDI contains aromatic groups, it produces benzene ring conjugated quinone chromophores, resulting in poor mechanical properties, chemical stability, and light and weather resistance in its products. Replacing currently used TDI with hydrogenated toluene diisocyanate (HTDI) could significantly improve the performance and quality of polyurethane, yielding substantial economic and social benefits. It is estimated that the economic benefits of HTDI are 198 times that of TDI. Furthermore, HTDI has significant application prospects in aerospace and military industries (ship coatings, new rocket propellant curing agents, transparent armor, etc.), high-end equipment manufacturing (functional coating materials for aircraft, high-speed trains, high-end automobiles, marine engineering equipment, etc.), new energy (coatings for new energy vehicles, wind turbine blades, photovoltaic brackets), and energy conservation and environmental protection industries. Currently, the world's large-scale factories producing aliphatic diisocyanates (including HTDI) are mainly located in Western Europe, North America, Japan, and other countries and regions. Companies such as Evonik, BASF, and Bayer in Germany, Rhodia in France, and Asahi Kasei in Japan possess and control the most advanced aliphatic diisocyanate (including HTDI) manufacturing technologies. my country has yet to achieve the industrialization of HTDI, and its domestic isocyanate industry faces significant challenges.

[0003] The main production method of HTDI uses toluenediamine (TDA) as a starting material. Under certain pressure, it undergoes catalytic hydrogenation to produce 1-methyl-2,4-cyclohexanediamine (HTDA), which is then converted to HTDI via a two-stage phosgenation reaction. Whoever masters advanced HTDI production technology first internationally will hold a leading position in the polyurethane industry. Efficient HTDA preparation technology, as a prerequisite for the industrialization of HTDI, has become crucial for the localization of HTDI production technology. In addition to being used as a raw material for HTDI production, HTDA can also be used to synthesize various drug molecules (such as antibiotics, antitumor drugs, and antiviral drugs), agrochemicals (insecticides, herbicides, etc.), high-performance polymers, functional polymer materials, coatings, dyes, and fragrances. Its direct market price as an end product is approximately 70,000 yuan / ton, indicating a very promising market prospect. Unfortunately, China still heavily relies on imports for HTDA, with BASF of Germany being the main supplier. Only Henan Leibairui New Material Technology Co., Ltd. achieved domestic production of HTDA in May 2024, but its production scale is small. The fundamental reason for the limitations in HTDA production technology lies in the complexity of the HTDA production process and the poor performance of the hydrogenation catalysts involved.

[0004] Currently, the main process for HTDA preparation is the two-step hydrogenation method using dinitrotoluene (DNT). This involves using DNT as the starting material, typically reducing it to TDA using a Ni-based catalyst, and then hydrogenating the TDA to HTDA using a noble metal catalyst. This method suffers from serious drawbacks, including complex processes, high costs, and low feedstock utilization. Therefore, there is an urgent need to develop a novel one-step hydrogenation process for DNT to HTDA, achieving highly selective control of HTDA production. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing two-step hydrogenation processes using precious metal catalysts and DNT, and provides a method and apparatus for one-step hydrogenation of DNT to HTDA based on TDA solvent. This method enables continuous production of HTDA from DNT in one step, eliminating the need for solvent separation during production, resulting in more stable and reliable product performance. Furthermore, it improves production efficiency and resource utilization through material recycling and product heat reuse.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a one-step hydrogenation method for preparing HTDA from DNT based on TDA solvent, comprising the following steps: (1) Pretreatment of reaction raw materials DNT was added to an appropriate amount of liquid TDA to prepare the first raw material solution. NaOH was added to an appropriate amount of liquid TDA and preheated to prepare the second raw material solution. The highly dispersed RuRhSn alloy catalyst precursor was pretreated to obtain the highly dispersed RuRhSn alloy catalyst. (2) Catalytic hydrogenation The highly dispersed RuRhSn alloy catalyst, the first feed liquid, and the second feed liquid were added to a high-pressure reactor. High-purity nitrogen was introduced into the high-pressure reactor to replace the air. High-purity hydrogen was then introduced into the high-pressure reactor. The reactor was stirred and heated at 100 r / min. When the temperature reached 120-200℃, the stirring rate was increased to 1500 r / min, and the reaction was started. The reaction lasted for 1-4 hours. (3) Material circulation After the reaction, the product undergoes solid-liquid separation. The liquid phase is sent to a distillation column, and the liquid material discharged from the bottom of the distillation column flushes the solid phase separated during the solid-liquid separation back into the high-pressure reactor for recycling. (4) Continuous production The product at the top of the distillation column is preheated sequentially by the second and first feed liquids using a jacketed heat exchanger before being collected and stored. The first and second feed liquids are then fed into a high-pressure reactor for continuous production.

[0007] As a preferred embodiment, in step (1), the liquid TDA is obtained by heating solid TDA to a liquid state at 120°C, the purity of DNT is not less than 99.9%, the ratio of DNT to TDA in the first raw material solution is 0.5g:50.0g, and the ratio of NaOH to TDA in the second raw material solution is 0.1:20g.

[0008] As a preferred option, the toluene diamine (TDA) is heated to 120°C.

[0009] As a preferred embodiment, in step (1), the pretreatment method for the highly dispersed RuRh alloy catalyst precursor is as follows: the highly dispersed RuRh alloy catalyst precursor is passed through a 200-mesh sieve and loaded into a fixed-bed reactor. Under the protection of high-purity nitrogen, the temperature is raised to 300-400℃ at a heating rate of 3-5℃ / min, and then hydrogen is introduced for reduction for 2-4 hours. The temperature is then lowered to room temperature to obtain the highly dispersed RuRhSn alloy catalyst. The support for the highly dispersed RuRhSn alloy catalyst is a TiO2-Al2O3 composite support. By mass ratio, TiO2:Al2O3=1:2, Ru:Rh:Sn=(2-5):1:1; the ratio of RuRhSn alloy catalyst to the first raw material liquid and the second raw material liquid is 0.01g:25g:25g.

[0010] As a preferred option, in step (2), the pressure of high-purity nitrogen is 2-6 MPa, and it is replaced 3-5 times; the pressure of hydrogen is 3-8 MPa.

[0011] As a preferred option, in step (3), the temperature of the distillation column bottom is controlled at 220°C.

[0012] As a preferred option, in step (3), the liquid phase component is sent to the distillation column after the product composition is analyzed by gas chromatography, gas chromatography-mass spectrometry and liquid chromatography.

[0013] Secondly, the present invention provides an apparatus for one-step hydrogenation of DNT to HTDA based on TDA solvent, comprising a first feed liquid tank, a second feed liquid tank, a high-pressure reactor, a solid-liquid separation device, a nitrogen tank, a hydrogen tank, a distillation column, and an HTDA product tank. The first feed liquid tank is used to store a first feed liquid, and the second feed liquid tank is used to store a second feed liquid. The high-pressure reactor is connected to the first feed liquid tank, the second feed liquid tank, and the solid-liquid separation device. A first feed pump is installed on the pipeline between the first feed liquid tank and the high-pressure reactor. The second feed liquid tank is connected to the high-pressure reactor... A second feed pump is installed on the pipeline between the reactor and the vessel. The nitrogen tank and hydrogen tank are connected to the inlet of the compressor, and the outlet of the compressor is connected to the high-pressure reactor. The upper part of the solid-liquid separation device is connected to the distillation column through a pipeline. The product outlet at the top of the distillation column is connected to the second raw material liquid tank jacket, the first raw material liquid tank jacket, and the HTDA product tank in sequence through a pipeline. A product transfer pump is installed on the pipeline between the product outlet at the top of the distillation column and the second raw material liquid tank jacket. The outlet of the distillation column bottom is connected to the high-pressure reactor after being paralleled with the bottom of the solid-liquid separation device. A catalyst feeding port is also installed on the high-pressure reactor.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. This invention uses TDA as a solvent, which can completely avoid the nucleophilic substitution side reaction between traditional organic alcohol solvents and HTDA. TDA can also be hydrogenated to HTDA, thereby improving the professionalism and yield of HTDA. Furthermore, no separation is required in subsequent processes. This not only reduces the impurities and isomers introduced in multiple reactions, making the performance of the HTDA product stable and reliable, but also saves significant costs caused by solvent separation.

[0015] 2. This invention directly converts DNT to HTDA through one-step catalytic hydrogenation. This process has high atom utilization and can effectively avoid the generation of intermediate products and by-products generated by multiple steps of reaction. It eliminates the need for complex intermediate product separation and purification steps, reduces raw material waste, shortens the process flow, and improves the stability and controllability of production. Furthermore, through continuous production, material recycling, and product heat recycling, it improves the production efficiency and raw material utilization of HTDA, which is more in line with the development concept of green chemical industry. Attached Figure Description

[0016] Figure 1 The image shows a scanning electron microscope image of the catalyst in Example 1. Figure 2 Here is the gas chromatogram of the product from Example 1; Figure 3 The images shown are chromatographic mass spectra of Example 1, where (a) is the liquid chromatogram of the product; (b) is the mass spectrum of the reactants; (c) is the mass spectrum of the product; and (d) is the mass spectrum of the byproducts. Figure 4 This is the standard curve plotted in the test examples of this invention; Figure 5 This is a schematic diagram of a device for one-step hydrogenation of DNT to HTDA based on TDA solvent according to the present invention; Reference numerals: 1-First raw material tank, 2-Second raw material tank, 3-First feed pump, 4-Second feed pump, 5-Nitrogen tank, 6-Hydrogen tank, 7-Compressor, 8-High-pressure reactor, 9-Solid-liquid separation device, 10-Distillation column, 11-HTDA product tank, 12-Product transfer pump. Detailed Implementation

[0017] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0018] Example 1 The dried, highly dispersed RuRhSn alloy catalyst precursor was sieved through a 200-mesh sieve and then packed into a fixed-bed reactor. Under high-purity nitrogen protection, the temperature was raised to 400℃ at a rate of 4℃ / min. Hydrogen was then introduced to reduce the precursor for 3 hours, followed by cooling to room temperature to obtain the RuRhSn alloy catalyst. The support for the highly dispersed RuRh alloy catalyst was TiO2-Al2O3, with a mass ratio of TiO2:Al2O3 = 1:2 and Ru:Rh:Sn = 4:1:1. Solid TDA was heated to a liquid state at 120℃ to obtain liquid TDA. The purity and crystallinity of commercially available 2,4-dinitrotoluene (DNT) were tested. 0.50g of 99.9% pure DNT was added to 50.0g of liquid TDA to prepare the first feed solution. 0.1g of NaOH and 40.0g of liquid TDA were used to prepare the second feed solution. High-purity nitrogen gas at 6 MPa was introduced to replace the air. 0.01 g of highly dispersed RuRhSn alloy catalyst, 25 g of the first raw material liquid, and 25 g of the second raw material liquid were added to 100 mL of high-pressure reactor. High-purity hydrogen gas at 6 MPa was then introduced into the high-pressure reactor. The reactor was stirred and heated at 100 r / min. When the temperature reached 180 °C, the stirring rate was increased to 1500 r / min, and the reaction time was started. After the reaction was completed, the pressure was slowly released, and the reaction mixture was transferred to a solid-liquid separation device for solid-liquid separation. The liquid phase components were analyzed by gas chromatography, gas chromatography-mass spectrometry, and liquid chromatography.

[0019] It should be noted that in this embodiment, the product is only analyzed by gas chromatography, gas chromatography-mass spectrometry and liquid chromatography, and is not subjected to distillation in a distillation column. This is mainly used for product analysis in the test examples below to verify the feasibility of the method of the present invention. In actual production, the product needs to be distilled, and the temperature of the distillation column bottom is controlled at 220°C.

[0020] Example 2 The solid phase component separated from the solid-liquid mixture in Example 1 was sent back to the high-pressure reactor and repeated 10 times according to the method in Example 1 to evaluate the reaction of the highly dispersed RuRhSn alloy catalyst.

[0021] Example 3 Similar to Example 1, except that the amount of catalyst was changed to 1.0 g, and a continuous reaction test was adopted. After 2 hours of reaction, the first and second feed liquids were introduced at a rate of 20 mL / min, and the products in the reactor were monitored in real time. The temperature of the distillation column bottom was controlled at 220°C, and the unreacted heavy components were added back to the feed storage tank.

[0022] Comparative Example 1 The method is the same as in Example 2, except that the liquid TDA solvent is changed to isopropanol.

[0023] Comparative Example 2 The method is the same as in Example 2, except that the liquid TDA solvent is changed to tetrahydrofuran.

[0024] Comparative Example 3 The method is the same as in Example 2, except that the metal Sn is removed.

[0025] Comparative Example 4 0.01 g of Raney nickel catalyst, 0.05 g of DNT, and 50 mL of methanol solvent, after ultrasonic mixing, were added to a 100 mL autoclave. Following this, a 6 MPa high-purity nitrogen gas was introduced to test the seal of the autoclave, and the air in the autoclave was replaced with high-purity nitrogen. Finally, the nitrogen in the autoclave was replaced with high-pressure hydrogen. Then, the high-purity hydrogen pressure was increased to 2.0 MPa, the temperature was raised to 90 °C, and the stirring speed was increased to 1500 r / min. The reaction was continued for 30 min. After the reaction, the product was centrifuged to remove the solid catalyst at the bottom. Next, a Ru-based catalyst was added to the autoclave, and the air in the autoclave was replaced with high-purity nitrogen. Finally, the nitrogen in the autoclave was replaced with high-pressure hydrogen, and the hydrogen pressure was increased to 6 MPa. The autoclave was then heated to the reaction temperature, and the stirring speed was increased to 1500 r / min. The reaction time was started when the reaction temperature reached 180 °C. Samples were taken during the reaction process, and the product composition was analyzed by gas chromatography, gas chromatography-mass spectrometry (GC-MS), and liquid chromatography (LC-MS).

[0026] Test case The products of Examples 1-2 and Comparative Examples 1-3 were subjected to chromatographic quantitative analysis.

[0027] Gas chromatography method: The reaction solution was analyzed using an Agilent 8860 gas chromatograph equipped with an HP-5 column. The analytical conditions were as follows: vaporization chamber temperature was 280℃; detector temperature was 280℃; programmed temperature was used, with column temperature at 60℃, initial hold time of 3 min, heating rate of 10℃ / min, final temperature at 200℃, and final hold time of 10 min; high-purity N2 was used as the carrier gas, with a flow rate of 30 mL / min and a split ratio of 1:45; the injection volume was 1 μL.

[0028] Gas chromatography-mass spectrometry (GC-MS) testing method: The reaction products were qualitatively analyzed using an Agilent 8860 GC / 5077 MSD GC-MS system equipped with an HP-5 MS column. The analytical conditions were the same as those for the Agilent 8860 GC.

[0029] Liquid Chromatography (LC) Method: The content of coupling byproducts (tar) was determined using an LC2030 Shimadzu high-performance liquid chromatograph equipped with a reversed-phase C18 column. The analytical conditions were as follows: the mobile phase was a methanol / water mixture with a volume ratio of 40 / 60; the rinsing rate was 1.0 mL / min; and the UV detection wavelength was 200-220 nm.

[0030] Determination of standard curve using external standard method (1) Preparation of standard substances: TDA was selected as the standard substance, and the product HTDA was used as the solvent to prepare standard solutions of 0.079 mol / L, 0.157 mol / L, 0.236 mol / L and 0.314 mol / L respectively.

[0031] (2) Plotting the standard curve: Inject the standard solutions into the gas chromatograph and record the peak area of ​​each standard solution; plot the standard curve with the concentration of the standard solution as the abscissa and the peak area of ​​TDA in the standard solution as the ordinate, see [reference]. Figure 3 .

[0032] (3) Sample determination: Inject the sample to be tested into the gas chromatograph and record the peak area of ​​TDA.

[0033] (4) Result calculation: The peak area of ​​the sample to be tested is substituted into the standard curve to determine the concentration of TDA in the sample; then the total amount of TDA in the sample is calculated. Based on the actual amount of TDA compared with the theoretical amount of TDA obtained by complete conversion of DNT, the selectivity of intermediate product TDA can be obtained.

[0034] Calculation formula:

[0035]

[0036] Since there are no other byproducts besides deamination (including tar) in the reaction, then .

[0037] The test data results are shown in Table 1 below. Figure 1-4 .

[0038] Table 1. Catalyst performance evaluation test data results

[0039] Through Table 1 and Figure 1-4 The data results show that the one-step hydrogenation method for preparing HTDA from DNT based on TDA solvent of the present invention is efficient and feasible for continuous production of HTDA.

[0040] Example 3 Please see the appendix Figure 4As shown, this embodiment provides a one-step hydrogenation apparatus for HTDA production from DNT based on a highly efficient Ru-based catalyst. The apparatus includes a first feed tank 1, a second feed tank 2, a high-pressure reactor 8, a solid-liquid separation device 9, a nitrogen tank 5, a hydrogen tank 6, a distillation column 10, and an HTDA product tank. The first feed tank 1 stores the first feed liquid, and the second feed tank 2 stores the second feed liquid. The high-pressure reactor 8 is connected to the first feed tank 1, the second feed tank 2, and the solid-liquid separation device 9. A first feed pump 3 is installed on the pipeline between the first feed tank 1 and the high-pressure reactor 8. A second feed pump 4 is installed on the pipeline between them. Nitrogen tank 5 and hydrogen tank 6 are respectively connected to the inlet of compressor 7. The outlet of compressor 7 is connected to high-pressure reactor 8. The upper part of solid-liquid separation device 9 is connected to distillation column 10 through a pipeline. The top product outlet of distillation column 10 is connected to the jacket of second raw material tank 2, the jacket of first raw material tank 1 and HTDA product tank 11 in sequence through pipelines. A product transfer pump 12 is installed on the pipeline between the top product outlet of distillation column 10 and the jacket of second raw material tank 2. The bottom outlet of distillation column 10 is connected to the bottom of solid-liquid separation device 9 and then connected to high-pressure reactor 8. Catalyst feeding port is also installed on high-pressure reactor 8.

[0041] In this embodiment, the first raw material liquid tank 1 is used to store the first raw material liquid prepared by DNT and TDA, and the second raw material liquid tank 2 is used to store the second raw material liquid prepared by NaOH and TDA.

[0042] 1-First feed liquid tank, 2-Second feed liquid tank, 3-First feed pump, 4-Second feed pump, 5-Nitrogen tank, 6-Hydrogen tank, 7-Compressor, 8-High-pressure reactor, 9-Solid-liquid separation unit, 10-Distillation column, 11-HTDA product tank, 12-Product transfer pump 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 and improvements made within the technical solution and conceptual framework of the present invention should be included within the protection scope of the present invention.

Claims

1. A one-step hydrogenation method for preparing HTDA from DNT using TDA solvent, characterized in that, Includes the following steps: (1) Pretreatment of reaction raw materials DNT was added to an appropriate amount of liquid TDA to prepare the first raw material solution. NaOH was added to an appropriate amount of liquid TDA and preheated to prepare the second raw material solution. The highly dispersed RuRhSn alloy catalyst precursor was pretreated to obtain the highly dispersed RuRhSn alloy catalyst. (2) Catalytic hydrogenation The highly dispersed RuRhSn alloy catalyst, the first feed liquid, and the second feed liquid were added to a high-pressure reactor. High-purity nitrogen was introduced into the high-pressure reactor to replace the air, and high-purity hydrogen was introduced into the high-pressure reactor. The reactor was stirred and heated at 100 r / min. When the temperature reached 120-200℃, the stirring rate was increased to 1500 r / min, and the reaction was started. The reaction lasted for 1-4 hours. (3) Material circulation After the reaction, the product undergoes solid-liquid separation. The liquid phase is sent to a distillation column, and the liquid material discharged from the bottom of the distillation column flushes the solid phase separated during the solid-liquid separation back into the high-pressure reactor for recycling. (4) Continuous production The product at the top of the distillation column is preheated sequentially by the second and first feed liquids using a jacketed heat exchanger before being collected and stored. The first and second feed liquids are then fed into a high-pressure reactor for continuous production.

2. The method for one-step hydrogenation of DNT to HTDA based on TDA solvent according to claim 1, characterized in that: In step (1), the liquid TDA is obtained by heating solid TDA to liquid state at 120°C, the purity of DNT is not less than 99.9%, the ratio of DNT to TDA in the first raw material solution is 0.5g:50.0g, and the ratio of NaOH to TDA in the second raw material solution is 0.1:20g.

3. The method for one-step hydrogenation of DNT to HTDA based on TDA solvent according to claim 1, characterized in that, In step (1), the pretreatment method of the highly dispersed RuRhSn alloy catalyst precursor is as follows: the highly dispersed RuRhSn alloy catalyst precursor is passed through a 200-mesh sieve and packed into a fixed-bed reactor. Under the protection of high-purity nitrogen, the temperature is raised to 300-400℃ at a heating rate of 3-5℃ / min. Then, hydrogen is introduced for reduction for 2-4 hours, and the temperature is lowered to room temperature to obtain the highly dispersed RuRhSn alloy catalyst. The support of the highly dispersed RuRhSn alloy catalyst is a TiO2-Al2O3 composite support. By mass ratio, TiO2:Al2O3=1:2, Ru:Rh:Sn=(2-5):1:1; the ratio of RuRhSn alloy catalyst to the first feed liquid and the second feed liquid is 0.01g:25g:25g.

4. The method for one-step hydrogenation of DNT to HTDA based on TDA solvent according to claim 3, characterized in that: In step (2), the pressure of high-purity nitrogen is 2-6 MPa, and it is replaced 3-5 times; the pressure of hydrogen is 3-8 MPa.

5. The method for one-step hydrogenation of DNT to HTDA based on TDA solvent according to claim 1, characterized in that: In step (3), the temperature of the distillation column bottom is controlled at 220℃.

6. The method for one-step hydrogenation of DNT to HTDA based on TDA solvent according to claim 1, characterized in that: In step (3), the liquid phase components are sent to the distillation column after being analyzed by gas chromatography, gas chromatography-mass spectrometry and liquid chromatography.

7. An apparatus for one-step hydrogenation of DNT to HTDA based on TDA solvent, characterized in that: The system includes a first feed liquid tank, a second feed liquid tank, a high-pressure reactor, a solid-liquid separation device, a nitrogen tank, a hydrogen tank, a distillation column, and an HTDA product tank. The first feed liquid tank stores the first feed liquid, and the second feed liquid tank stores the second feed liquid. The high-pressure reactor is connected to the first feed liquid tank, the second feed liquid tank, and the solid-liquid separation device. A first feed pump is installed on the pipeline between the first feed liquid tank and the high-pressure reactor, and a second feed pump is installed on the pipeline between the second feed liquid tank and the high-pressure reactor. The nitrogen tank and the hydrogen tank are connected to the inlet of the compressor, and the outlet of the compressor is connected to the high-pressure reactor. The upper part of the solid-liquid separation device is connected to the distillation column through a pipeline. The top product outlet of the distillation column is connected to the jacket of the second feed liquid tank, the jacket of the first feed liquid tank, and the HTDA product tank in sequence through pipelines. A product transfer pump is installed on the pipeline between the top product outlet of the distillation column and the jacket of the second feed liquid tank. The bottom outlet of the distillation column is connected to the high-pressure reactor after being paralleled to the bottom of the solid-liquid separation device. The high-pressure reactor is also equipped with a catalyst feeding port.

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