Method for preparing 4, 4 '-diaminodiphenyl ether

Abstract

The invention relates to a method for preparing 4, 4 '-diaminodiphenyl ether. According to the method, 4, 4 '-dinitrodiphenyl ether is used as an initial raw material, and 4, 4'-diaminodiphenyl ether is prepared through catalytic hydrogenation reduction of a supported catalyst; in the preparation of the catalyst, the dispersion degree of the metal active component on the carrier is improved by virtue of the membrane dispersion microreactor on the premise of not using a surfactant, the metal dosage is reduced, the supported structure is integrally formed, and continuous production of the catalyst precursor is realized. The preparation process provided by the invention is more green and efficient, is applied to hydrogenation reduction of 4, 4 '-dinitrodiphenyl ether under mild reaction conditions, shows excellent performance, and reduces the production cost.

Description

Technical Field

[0001] The present invention relates to a method for synthesizing 4,4'-diaminodiphenyl ether, an important chemical raw material, and in particular to a method for preparing 4,4'-diaminodiphenyl ether by taking 4,4'-dinitrodiphenyl ether as a substrate and a catalyst thereof. Background Art

[0002] 4,4'-Diaminodiphenyl ether is a fine chemical intermediate with high added value. It can be used to synthesize high-temperature resistant polymer materials such as engineering plastics polyimide, and can be used as a raw material and cross-linking agent for synthetic polymers such as high-performance heat-resistant epoxy resin polyurethane, and can replace carcinogenic benzidine to produce azo dyes and reactive dyes. At present, the main method for producing 4,4'-diaminodiphenyl ether is through the reduction of 4,4'-dinitrodiphenyl ether. The reduction method is divided into chemical reduction method and catalytic hydrogenation method. The chemical reduction method mainly includes iron powder reduction method, hydrazine hydrate method, alkali sulfide reduction method, etc. The catalytic hydrogenation method uses hydrogen as a reducing agent to reduce the substrate under the action of a hydrogenation catalyst. Compared with the chemical reduction method, the catalytic hydrogenation method has the advantages of simple synthesis process, high product purity, and less "three wastes".

[0003] At present, there are two main types of catalysts used in catalytic hydrogenation. One type uses precious metal catalysts such as Pt and Pd, but the high price greatly affects the production cost; the other type uses skeleton nickel catalysts. Although the catalyst is cheap, it is not easy to preserve and has safety hazards such as flammability and explosion. In order to prepare 4,4'-diaminodiphenyl ether more efficiently and at low cost, researchers have studied hydrogenation catalysts. Patent CN108906101 uses an impregnation method to synthesize a catalyst with nitrogen-doped activated carbon as a carrier and nickel or iron as an active metal. However, the preparation of the carrier requires the use of an autoclave at 100-200°C, which has high requirements for equipment. Patent CN110639553 synthesized an iron-cobalt composite carbon copper catalyst for hydrogenation preparation of 4,4'-diaminodiphenyl ether, but the surfactant polyethylene glycol was used in the synthesis of the carrier, the calcination temperature was as high as 800-900°C, the calcination atmosphere was composed of nitrogen and water vapor, and the preparation process was complicated.

[0004] In summary, the synthesis of 4,4'-diaminodiphenyl ether by hydrogenation reduction using 4,4'-dinitrodiphenyl ether as raw material under the action of heterogeneous non-precious metal catalysts is a green and sustainable process route. Therefore, it is of great significance to develop a heterogeneous non-precious metal catalyst system with simple preparation process, no surfactant and high hydrogenation activity and apply it to the preparation of 4,4'-diaminodiphenyl ether. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies of the prior art and provide a method for preparing 4,4'-diaminodiphenyl ether. The method uses 4,4'-dinitrodiphenyl ether as an initial raw material and obtains 4,4'-diaminodiphenyl ether through catalytic hydrogenation reduction. The present invention provides a method for preparing a supported catalyst, which uses a membrane dispersion microreactor to improve the dispersion of metal active components on a carrier without using a surfactant, reduces the amount of metal, and forms a supported structure in one piece. It also realizes continuous production of catalyst precursors, and the preparation process is more green and efficient. The catalyst is applied to the hydrogenation reduction of 4,4'-dinitrodiphenyl ether under mild reaction conditions, exhibits excellent performance in the reaction, and reduces production costs.

[0006] The technical solution of the present invention is:

[0007] A method for preparing 4,4'-diaminodiphenyl ether, the method comprising the following steps:

[0008] Put 4,4'-dinitrodiphenyl ether (DNDPE), N,N-dimethylacetamide (DMAC) and a supported catalyst into a reactor, introduce hydrogen into the reactor, react at 50-100°C for 20-800min, and generate 4,4'-diaminodiphenyl ether by hydrogenation reduction reaction;

[0009] Wherein, the mass ratio is 4,4'-dinitrodiphenyl ether: catalyst = 500-2:1; the molar ratio is DNDPE: DMAC = 1:3-15; the hydrogen pressure is 1.0-3.5MPa;

[0010] The supported catalyst comprises an active component and a carrier, wherein the carrier is silicon dioxide, the active component is a main metal M1, or a main metal M1 and a metal M2; the molar ratio of the active component to silicon dioxide is 1:1-15; the molar ratio of the main metal M1 to the auxiliary metal M2 is 1-15:1;

[0011] The main metal M1 of the catalyst is Ni;

[0012] The promoter metal M2 of the catalyst is Co, Cu, Fe, Zn or Ce;

[0013] The method for preparing the supported catalyst comprises the following steps:

[0014] Metal nitrate and tetraethyl silicate are dissolved in anhydrous ethanol to obtain a dispersed phase solution A; NaOH is dissolved in distilled water to obtain a continuous phase solution B; the dispersed phase solution A and the continuous phase solution B are introduced into a membrane dispersion microreactor at a flow rate ratio of 1:0.5-1.5, and then passed through a retention tube at 55-65° C. to generate a slurry; the slurry is centrifuged, the precipitate is collected, washed, dried, calcined in air at 300-500° C., and reduced in a hydrogen atmosphere at 400-600° C. to obtain a catalyst;

[0015] The total concentration of metal nitrate in the dispersed phase solution A is 0.04-0.2 mol / L; the concentration of tetraethyl silicate is 0.1-1.5 mol / L;

[0016] Wherein, the NaOH concentration in the continuous phase solution B is 0.5-1.2 mol / L;

[0017] The material of the residence tube is polytetrafluoroethylene, and the inner diameter is 1.5-2.5 mm; the residence time is 1-5 min.

[0018] The total flow rate is 1 mL / min-20 mL / min, and solution A and solution B are mixed in a membrane dispersion microreactor. The preferred membrane dispersion reactor has a stainless steel microfiltration membrane with a pore size of 0.5-5 μm, a diameter of 6.5-100 mm, and a thickness of 1.3-20 mm.

[0019] The essential features of the present invention are:

[0020] The present invention uses a membrane dispersion microreactor to continuously prepare a catalyst precursor. In the membrane dispersion microreactor, the cross-flow shearing of the dispersed phase by the microfiltration membrane allows the metal ions and tetraethyl silicate in the dispersed phase to be uniformly and quickly mixed with the hydroxide in the continuous phase, thereby improving the mixing efficiency and mass transfer efficiency, thereby achieving high dispersion of the metal active components on the carrier without using a surfactant, thereby improving the hydrogenation capacity of the catalyst.

[0021] In the heterogeneous catalyst of the supported structure of silica-supported Ni-Co bimetallic used in the present invention, the presence of silica provides an acid site for the nitro hydrogenation reduction reaction, promoting the hydrogenation of the reactants. The mutual doping of the active components Ni and Co plays a synergistic role, enhances the hydrogenation activity of the catalyst, and promotes the conversion of the intermediate.

[0022] The beneficial effects of the present invention are:

[0023] The invention provides a method for synthesizing 4,4-diaminodiphenyl ether from 4,4-dinitrodiphenyl ether, and the preferred conditions for the catalytic reaction in the invention are 50-100° C. and 1MPa H2 pressure, which has low requirements on reaction equipment, is economically feasible, has a simple reaction method, and generates less "three wastes" during the reaction process. The conversion rate of 4,4'-dinitrodiphenyl ether is 100%, and the yield of 4,4'-diaminodiphenyl ether is 99.09%.

[0024] The catalyst used in the present invention is synthesized by using a membrane dispersion microreactor, and has the advantages of low metal dosage, high dispersion, integrated support structure and green and simple preparation process. In addition, the catalyst can continuously prepare precursors and has the potential for mass production. The catalyst also exhibits excellent activity and stability in the nitro catalytic hydrogenation reaction and has good application prospects. DETAILED DESCRIPTION

[0025] The synthetic route of the present invention is as follows:

[0026]

[0027] The technical features of the present invention are further described below by combining implementation cases:

[0028] Example 1: Preparation of 10-Ni-SiO2-400-500

[0029] 2.91g Ni(NO3)2·6H2O (0.01mol) and 2.08g tetraethyl silicate (TEOS, 0.01mol) were mixed in 100mL anhydrous ethanol to obtain a metal salt-tetraethyl silicate mixed solution. 4g NaOH (0.1mol) was dissolved in 100mL distilled water to prepare a 1mol / L NaOH solution. The two solutions were passed into a membrane dispersion microreactor equipped with a stainless steel microfiltration membrane with a pore size of 1μm, a diameter of 6.5mm and a thickness of 1.5mm by a continuous feed pump at a flow rate of 5mL / min, and then passed through a polytetrafluoroethylene tube with an inner diameter of 2mm and a length of 6.4m in a 60℃ water bath to obtain a slurry. The slurry was centrifuged, the precipitate was collected, and washed with distilled water and ethanol in turn. The solid was dried at 100℃ for 6h, calcined at 400℃ in air for 4h, and the obtained material was reduced at 500℃ in hydrogen for 3h.

[0030] Example 2-4: Preparation of 10-Ni-3SiO2-400-500, 10-Ni-5SiO2-400-500, 10-Ni-7SiO2-400-500, and 10-Ni-9SiO2-400-500

[0031] The other steps are the same as in Example 1, except that the amount of tetraethyl silicate is changed to 6.25 g, 10.42 g, 14.58 g, and 18.75 g, respectively. Finally, four different materials are obtained: 10-Ni-3SiO2-400-500, 10-Ni-5SiO2-400-500, 10-Ni-7SiO2-400-500, and 10-Ni-9SiO2-400-500 catalysts.

[0032] The catalyst is represented by R-xM1-yM2-zSiO2-ab, wherein R represents the total flow rate, M1 represents the main metal, M2 represents the auxiliary metal, x and y represent the ratio of M1 and M2 to the total metal molar amount in the catalyst, z represents the molar ratio of silica to the total metal, a represents the catalyst calcination temperature, and b represents the catalyst reduction temperature.

[0033] Example 5: Preparation of 10-0.75Ni0.25Cu-5SiO2-400-500

[0034] 2.18g Ni(NO3)2·6H2O (0.0075mol), 0.61g Cu(NO3)2·3H2O (0.0025mol) and 10.4g tetraethyl silicate (TEOS, 0.05mol) were dissolved in 100mL anhydrous ethanol and mixed to obtain a metal salt-tetraethyl silicate mixed solution. 4g NaOH (0.1mol) was dissolved in 100mL distilled water to prepare a 1mol / L NaOH solution. The two solutions were respectively passed into a membrane dispersion microreactor equipped with a stainless steel microfiltration membrane with a pore size of 1μm, a diameter of 6.5mm and a thickness of 1.5mm by a continuous feed pump at a flow rate of 5mL / min, and then passed through a polytetrafluoroethylene tube with an inner diameter of 2mm and a length of 6.4m in a water bath at 60℃ to obtain a slurry. The slurry was centrifuged, the precipitate was collected, and washed with distilled water and ethanol in turn. The solid was dried at 100°C for 6 hours, calcined at 400°C in air for 4 hours, and the resulting material was reduced in hydrogen at 500°C for 3 hours. Example 6-9: Preparation of 10-0.75Ni0.25Cu-5SiO2-400-500, 10-0.75Ni0.25Zn-5SiO2-400-500, 10-0.75Ni0.25Fe-5SiO2-400-500, and 10-0.75Ni0.25Ce-5SiO2-400-500

[0035] The other steps are the same as those in Example 5, except that 0.61g Cu(NO3)2·3H2O is replaced by 0.73g Co(NO3)2·6H2O, 0.74g Zn(NO3)2·6H2O, 1.01g Fe(NO3)2·9H2O, and 1.08g Ce(NO3)2·6H2O (the molar amount remains unchanged). Finally, four different materials are obtained: 10-0.75Ni0.25Cu-5SiO2-400-500, 10-0.75Ni0.25Zn-5SiO2-400-500, 10-0.75Ni0.25Fe-5SiO2-400-500, and 10-0.75Ni0.25Ce-5SiO2-400-500 catalysts.

[0036] Example 10: Preparation of 10-0.5Ni0.5Co-5SiO2400-500

[0037] 1.45g Ni(NO3)2·6H2O (0.005mol), 1.46g Co(NO3)2·6H2O (0.005mol) and 10.4g tetraethyl silicate (TEOS, 0.05mol) were dissolved in 100mL anhydrous ethanol and mixed to obtain a metal salt-tetraethyl silicate mixed solution. 4g NaOH (0.1mol) was dissolved in 100mL distilled water to prepare a 1mol / L NaOH solution. The two solutions were respectively passed into a membrane dispersion microreactor equipped with a stainless steel microfiltration membrane with a pore size of 1μm, a diameter of 6.5mm and a thickness of 1.5mm by a continuous feed pump at a flow rate of 5mL / min, and then passed through a polytetrafluoroethylene tube with an inner diameter of 2mm and a length of 6.4m in a water bath at 60℃ to obtain a slurry. The slurry was centrifuged, the precipitate was collected, and washed with distilled water and ethanol in turn. The solid was dried at 100°C for 6 hours, calcined at 400°C in air for 4 hours, and the obtained material was reduced in hydrogen at 500°C for 3 hours.

[0038] Examples 11-14: Preparation of 10-0.83Ni0.17Co-5SiO2-400-500, 10-0.875Ni0.125Co-5SiO2-400-500, 10-0.9Ni0.1Co-5SiO2-400-500, and 10-0.92Ni0.08Co-5SiO2-400-500

[0039] The other steps are the same as those in Example 10, except that the amounts of Ni(NO3)2·6H2O are 2.42g, 2.54g, 2.62g, and 2.66g, respectively, and the amounts of Co(NO3)2·6H2O are 0.49g, 0.36g, 0.29g, and 0.24g, respectively (the total molar amount of the metal remains unchanged). Finally, four different materials are obtained: 10-0.83Ni0.17Co-5SiO2-400-500, 10-0.875Ni0.125Co-5SiO2-400-500, 10-0.9Ni0.1Co-5SiO2-400-500 catalysts.

[0040] Example 15: Preparation of 1-0.9Ni0.1Co-5SiO2-400-500

[0041] 2.62g Ni(NO3)2·6H2O (0.009mol), 0.29g Co(NO3)2·6H2O (0.001mol) and 10.4g tetraethyl silicate (TEOS, 0.05mol) were dissolved in 100mL anhydrous ethanol and mixed to obtain a metal salt-tetraethyl silicate mixed solution. 4g NaOH (0.1mol) was dissolved in 100mL distilled water to prepare a 1mol / L NaOH solution. The two solutions were respectively passed into a membrane dispersion microreactor equipped with a stainless steel microfiltration membrane with a pore size of 1μm, a diameter of 6.5mm and a thickness of 1.5mm by a continuous feed pump at a flow rate of 0.5mL / min, and then passed through a polytetrafluoroethylene tube with an inner diameter of 2mm and a length of 3.2m in a water bath at 60℃ to obtain a slurry. The slurry was centrifuged, the precipitate was collected, and washed with distilled water and ethanol in turn. The solid was dried at 100°C for 6 hours, calcined at 400°C in air for 4 hours, and the obtained material was reduced in hydrogen at 500°C for 3 hours. 2: Preparation of -400-500, 12.5-0.9Ni0.1Co-5SiO2-400-500, 15-0.9Ni0.1Co-5SiO2-400-500, 17.5-0.9Ni0.1Co-5SiO2-400-500, 20-0.9Ni0.1Co-5SiO2-400-500

[0042] The other steps are the same as those in Example 15, except that the solution flow rates are changed to 2.5 mL / min, 3.75 mL / min, 6.25 mL / min, 7.5 mL / min, 8.75 mL / min, and 10 mL / min (residence time remains unchanged). Finally, six different materials are obtained: 5-0.9Ni0.1Co-5SiO2-400-500, 7.5-0.9Ni0.1Co-5SiO2-400-500, 12.5-0.9Ni0.1Co-5SiO2-400-500, 15-0.9Ni0.1Co-5SiO2-400-500, 17.5-0.9Ni0.1Co-5SiO2-400-500, and 20-0.9Ni0.1Co-5SiO2-400-500 catalysts.

[0043] Example 22: Preparation of 10-0.9Ni0.1Co-5SiO2-300-500

[0044] 2.62g Ni(NO3)2·6H2O (0.009mol), 0.29g Co(NO3)2·6H2O (0.001mol) and 10.4g tetraethyl silicate (TEOS, 0.05mol) were dissolved in 100mL anhydrous ethanol and mixed to obtain a metal salt-tetraethyl silicate mixed solution. 4g NaOH (0.1mol) was dissolved in 100mL distilled water to prepare a 1mol / L NaOH solution. The two solutions were respectively passed into a membrane dispersion microreactor equipped with a stainless steel microfiltration membrane with a pore size of 1μm, a diameter of 6.5mm and a thickness of 1.5mm by a continuous feed pump at a flow rate of 5mL / min, and then passed through a polytetrafluoroethylene tube with an inner diameter of 2mm and a length of 6.4m in a 60℃ water bath to obtain a slurry. The slurry was centrifuged, the precipitate was collected, and washed with distilled water and ethanol in turn. The solid was dried at 100°C for 6 hours, calcined at 300°C in air for 4 hours, and the obtained material was reduced in hydrogen at 500°C for 3 hours.

[0045] Examples 23-25: Preparation of 10-0.9Ni0.1Co-5SiO2-350-500, 10-0.9Ni0.1Co-5SiO2-450-500, 10-0.9Ni0.1Co-5SiO2-500-500

[0046] The other steps are the same as those in Example 22, except that the calcination temperature in air is changed to 350°C, 450°C, and 500°C (the reduction temperature remains unchanged). Finally, three different materials are obtained: 10-0.9Ni0.1Co-5SiO2-350-500, 10-0.9Ni0.1Co-5SiO2-450-500, and 10-0.9Ni0.1Co-5SiO2-500-500 catalysts.

[0047] Example 26: Preparation of 10-0.9Ni0.1Co-5SiO2-400-400

[0048] 2.62g Ni(NO3)2·6H2O (0.009mol), 0.29g Co(NO3)2·6H2O (0.001mol) and 10.4g tetraethyl silicate (TEOS, 0.05mol) were dissolved in 100mL anhydrous ethanol and mixed to obtain a metal salt-tetraethyl silicate mixed solution. 4g NaOH (0.1mol) was dissolved in 100mL distilled water to prepare a 1mol / L NaOH solution. The two solutions were respectively passed into a membrane dispersion microreactor equipped with a stainless steel microfiltration membrane with a pore size of 1μm, a diameter of 6.5mm and a thickness of 1.5mm by a continuous feed pump at a flow rate of 5mL / min, and then passed through a polytetrafluoroethylene tube with an inner diameter of 2mm and a length of 6.4m in a 60℃ water bath to obtain a slurry. The slurry was centrifuged, the precipitate was collected, and washed with distilled water and ethanol in turn. The solid was dried at 100°C for 6 hours, calcined at 400°C in air for 4 hours, and the obtained material was reduced in hydrogen at 400°C for 3 hours.

[0049] Examples 27-29: Preparation of 10-0.9Ni0.1Co-5SiO2-400-450, 10-0.9Ni0.1Co-5SiO2-400-550, 10-0.9Ni0.1Co-5SiO2-400-600

[0050] The other steps are the same as those in Example 26, except that the reduction temperature in hydrogen is changed to 450°C, 550°C, and 600°C (the calcination temperature remains unchanged). Finally, three different materials are obtained: 10-0.9Ni0.1Co-5SiO2-400-450, 10-0.9Ni0.1Co-5SiO2-400-550, and 10-0.9Ni0.1Co-5SiO2-400-600 catalysts.

[0051] Example 30: Hydrogenation reduction of 4,4'-dinitrodiphenyl ether

[0052] The reaction was carried out in a 50 mL stainless steel reactor, and 0.065 g of the catalyst obtained in Catalyst Preparation Example 1-5, 4,4'-dinitrodiphenyl ether (1.3 g, 5 mmol) and N,N-dimethylacetamide (2.2113 g, 25 mmol) were added. Before the reaction, the gas in the reactor was replaced by purging with H2 five times. Hydrogenation reduction was carried out at 3 MPa H2 and 100 ° C, and the stirring rate was 1500 rpm. After the reaction for 30 min, the reaction solution was filtered and the catalyst was analyzed by high performance liquid chromatography external standard method. The reaction results are shown in Table 1.

[0053] Table 1 Effect of nickel-silicon molar ratio on reaction

[0054]

[0055] It can be seen from the data in Table 1 that as the nickel-silicon molar ratio increases from 1:1 to 1:5, the hydrogenation performance of the catalyst gradually improves; as the nickel-silicon molar ratio further increases, the hydrogenation performance of the catalyst decreases, and the preferred nickel-silicon molar ratio is 1:5.

[0056] Example 31: Hydrogenation reduction of 4,4'-dinitrodiphenyl ether

[0057] The reaction was carried out in a 50 mL stainless steel reactor, and 0.065 g of the catalyst obtained in Catalyst Preparation Example 6-10, 4,4'-dinitrodiphenyl ether (1.3 g, 5 mmol) and N,N-dimethylacetamide (2.2113 g, 25 mmol) were added. Before the reaction, the gas in the reactor was replaced by purging with H2 five times. Hydrogenation reduction was carried out at 3 MPa H2 and 100 ° C, and the stirring rate was 1500 rpm. After the reaction for 30 min, the reaction solution was filtered and the catalyst was analyzed by high performance liquid chromatography external standard method. The reaction results are shown in Table 2.

[0058] Table 2 Effect of the second metal on the reaction

[0059]

[0060] It can be seen from the data in Table 2 that the introduction of metals Cu, Zn, Fe and Ce did not improve the catalyst performance, but weakened the hydrogenation activity. When the second metal Co was added, the hydrogenation activity of the catalyst was improved. Preferably, the second metal component is Co.

[0061] Example 32: Hydrogenation reduction of 4,4'-dinitrodiphenyl ether

[0062] The reaction was carried out in a 50 mL stainless steel reactor, and 0.065 g of the catalyst obtained in Catalyst Preparation Examples 11-15, 4,4'-dinitrodiphenyl ether (1.3 g, 5 mmol) and N,N-dimethylacetamide (2.2113 g, 25 mmol) were added. Before the reaction, the gas in the reactor was replaced by purging with H2 five times. Hydrogenation reduction was carried out at 3 MPa H2 and 100 ° C, and the stirring rate was 1500 rpm. After the reaction for 20 min, the reaction solution was filtered and the catalyst was analyzed by high performance liquid chromatography external standard method. The reaction results are shown in Table 3.

[0063] Table 3 Effect of nickel-cobalt molar ratio on reaction

[0064]

[0065]

[0066] It can be seen from the data in Table 3 that as the nickel-cobalt molar ratio increases from 1:1 to 9:1, the synergistic effect between nickel and cobalt metals gradually increases, and the catalyst hydrogenation activity gradually improves. However, when the nickel-cobalt molar ratio continues to increase to 11:1, the catalyst activity decreases. The preferred nickel-cobalt molar ratio is 9:1.

[0067] Example 33: Hydrogenation reduction of 4,4'-dinitrodiphenyl ether

[0068] The reaction was carried out in a 50 mL stainless steel reactor, and 0.065 g of the catalyst obtained in Catalyst Preparation Examples 16-19, 4,4'-dinitrodiphenyl ether (1.3 g, 5 mmol) and N,N-dimethylacetamide (2.2113 g, 25 mmol) were added. Before the reaction, the gas in the reactor was replaced by purging with H2 five times. Hydrogenation reduction was carried out at 3 MPa H2 and 100 ° C, and the stirring rate was 1500 rpm. After the reaction for 30 min, the reaction solution was filtered and the catalyst was analyzed by high performance liquid chromatography external standard method. The reaction results are shown in Table 4.

[0069] Table 4 Effect of total flow rate on reaction

[0070]

[0071] It can be seen from the data in Table 4 that when the total flow rate is low, the catalyst hydrogenation performance is poor. As the flow rate increases to 7.5 ml / min, the hydrogenation activity is significantly improved. When the total flow rate reaches 12.5 ml / min, the catalyst performance decreases. The preferred total flow rate is 10 ml / min.

[0072] Example 34: Hydrogenation reduction of 4,4'-dinitrodiphenyl ether

[0073] In a 50mL stainless steel reactor, 0.065g of the catalyst obtained in Catalyst Preparation Examples 21-24, 4,4'-dinitrodiphenyl ether (1.3g, 5mmol) and N,N-dimethylacetamide (2.2113g, 25mmol) were added. Before the reaction, the gas in the reactor was replaced by purging with H2 five times. Hydrogenation reduction was carried out at 3MPa H2 and 80°C, with a stirring rate of 1500rpm. After 30min of reaction, the reaction solution was filtered and the catalyst was analyzed by HPLC external standard method. The reaction results are shown in Table 5.

[0074] Table 5 Effect of calcination temperature on reaction

[0075]

[0076] It can be seen from the data in Table 5 that when the calcination temperature increases to 350°C, the hydrogenation performance of the catalyst increases accordingly; however, when the calcination temperature is further increased to 450°C, the catalytic performance of the catalyst decreases, and the preferred calcination temperature is 400°C.

[0077] Example 35: Hydrogenation reduction of 4,4'-dinitrodiphenyl ether

[0078] In a 50mL stainless steel reactor, 0.065g of the catalyst obtained in Catalyst Preparation Examples 25-28, 4,4'-dinitrodiphenyl ether (1.3g, 5mmol), and N,N-dimethylacetamide (2.2113g, 25mmol) were added. Before the reaction, the gas in the reactor was replaced by purging with H2 five times. Hydrogenation reduction was carried out at 3MPa H2 and 80°C, with a stirring rate of 1500rpm. After the reaction for 30min, the reaction solution was filtered and the catalyst was analyzed by HPLC external standard method. The reaction results are shown in Table 6.

[0079] Table 6 Effect of reduction temperature on reaction

[0080]

[0081] It can be seen from the data in Table 6 that with the increase of reduction temperature, the hydrogenation performance of the catalyst gradually improves; however, when the reduction temperature is further increased to 550°C, the hydrogenation performance of the catalyst decreases significantly. The preferred reduction temperature is 500°C.

[0082] Example 36: Hydrogenation reduction of 4,4'-dinitrodiphenyl ether

[0083] In a 50mL stainless steel reactor, the catalyst 10-0.9Ni0.1Co-5SiO2-400-500, 4,4'-dinitrodiphenyl ether (1.3g, 5mmol), and N,N-dimethylacetamide (2.2113g, 25mmol) obtained in the catalyst preparation example 14 were added. Before the reaction, the gas in the reactor was replaced by purging with H2 five times. Hydrogenation reduction was carried out at 3MPa H2, 80°C and different catalyst dosages (0.065g, 0.052g, 0.039g, 0.026g, 0.013g), and the stirring rate was 1500rpm. After the complete reaction, the reaction solution was filtered and the catalyst was analyzed by high performance liquid chromatography external standard method. The reaction results are shown in Table 7.

[0084] Table 7 Effect of catalyst dosage on reaction

[0085]

[0086] It can be seen from the data in Table 7 that as the amount of catalyst decreases, the reaction time gradually increases. Taking into account factors such as catalyst cost, energy consumption and product yield, the preferred amount of catalyst is 0.026 g, which is 2% of the substrate mass.

[0087] Example 37: Hydrogenation reduction of 4,4'-dinitrodiphenyl ether

[0088] The reaction was carried out in a 50 mL stainless steel reactor, and the catalyst 10-0.9Ni0.1Co-5SiO2-400-500 (0.026 g) obtained in Example 14, 4,4'-dinitrodiphenyl ether (1.3 g, 5 mmol), and N,N-dimethylacetamide (2.2113 g, 25 mmol) were added. Before the reaction, the gas in the reactor was replaced by purging with H2 five times. Hydrogenation reduction was carried out at 3 MPa H2 and different temperatures (90°C, 70°C, 60°C, 50°C) with a stirring rate of 1500 rpm. After the reaction was complete, the reaction solution was filtered and the catalyst was analyzed by high performance liquid chromatography external standard method. The reaction results are shown in Table 8.

[0089] Table 8 Effect of reaction temperature on reaction

[0090]

[0091] It can be seen from the data in Table 8 that the reaction temperature gradually decreases and the reaction time gradually increases. Considering factors such as energy consumption and product yield, the preferred reaction temperature is 80°C.

[0092] Example 38: Hydrogenation reduction of 4,4'-dinitrodiphenyl ether

[0093] The reaction was carried out in a 50 mL stainless steel reactor, and the catalyst 10-0.9Ni0.1Co-5SiO2-400-500 (0.026 g), 4,4'-dinitrodiphenyl ether (1.3 g, 5 mmol), and N,N-dimethylacetamide (2.2113 g, 25 mmol) obtained in Example 14 were added. Before the reaction, the gas in the reactor was replaced by purging with H2 five times. Hydrogenation reduction was carried out under different hydrogen pressures (2.5 MPa, 2 MPa, 1.5 MPa, 1 MPa) and 80 ° C, with a stirring rate of 1500 rpm. After the reaction was complete, the reaction solution was filtered and the catalyst was analyzed by high performance liquid chromatography external standard method. The reaction results are shown in Table 9.

[0094] Table 9 Effect of hydrogen pressure on reaction

[0095]

[0096] It can be seen from the data in Table 9 that as the hydrogen pressure decreases, the time required to complete the reaction gradually increases. However, lower hydrogen pressure can reduce the requirements for equipment. Taking all factors into consideration, the preferred hydrogen pressure is 1 MPa.

[0097] Matters not covered by the present invention are known technologies.

Claims

1. A method for preparing 4,4'-diaminodiphenyl ether, characterized in that the method comprises the following steps: Put 4,4'-dinitrodiphenyl ether (DNDPE), N,N-dimethylacetamide (DMAC) and a supported catalyst into a reactor, introduce hydrogen into the reactor, react at 50-100°C for 20-800min, and generate 4,4'-diaminodiphenyl ether by hydrogenation reduction reaction; in, The mass ratio is 4,4'-dinitrodiphenyl ether: catalyst = 500-2:1; the molar ratio is DNDPE: DMAC = 1:3-15; the hydrogen pressure is 1.0-3.5MPa; The supported catalyst comprises an active component and a carrier, wherein the carrier is silicon dioxide, the active component is a main metal M1, or a main metal M1 and a metal M2; the molar ratio of the active component to silicon dioxide is 1:1-15; the molar ratio of the main metal M1 to the auxiliary metal M2 is 1-15:1; The main metal M1 of the catalyst is Ni; The promoter metal M2 of the catalyst is Co, Cu, Fe, Zn or Ce; The method for preparing the supported catalyst comprises the following steps: Metal nitrate and tetraethyl silicate are dissolved in anhydrous ethanol to obtain a dispersed phase solution A; NaOH is dissolved in distilled water to obtain a continuous phase solution B; the dispersed phase solution A and the continuous phase solution B are introduced into a membrane dispersion microreactor at a flow rate ratio of 1:0.5-1.5, and then passed through a retention tube at 55-65° C. to generate a slurry; the slurry is centrifuged, the precipitate is collected, washed, dried, calcined in air at 300-500° C., and reduced in a hydrogen atmosphere at 400-600° C. to obtain a catalyst; The total concentration of metal nitrate in the dispersed phase solution A is 0.04-0.2 mol / L; the concentration of tetraethyl silicate is 0.1-1.5 mol / L; The NaOH concentration in the continuous phase solution B is 0.5-1.2 mol / L.

2. The method for preparing 4,4'-diaminodiphenyl ether according to claim 1, characterized in that the residence tube is made of polytetrafluoroethylene and has an inner diameter of 1.5-2.5 mm; and the residence time is 1-5 min.

3. The method for preparing 4,4'-diaminodiphenyl ether as claimed in claim 1, The invention is characterized by a method for preparing 4,4'-diaminodiphenyl ether. It is characterized by a total flow rate of 1 mL / min-20 mL / min.

4. The method for preparing 4,4'-diaminodiphenyl ether as claimed in claim 1, The invention is characterized by a method for preparing 4,4'-diaminodiphenyl ether. The invention is characterized in that the stainless steel microfiltration membrane of the membrane dispersion reactor has a pore size of 0.5-5 μm, a diameter of 6.5-100 mm, and a thickness of 1.3-20 mm.

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