Nitrobenzene hydrogenation composite catalyst as well as preparation method and application thereof

Abstract

The invention provides a nitrobenzene hydrogenation composite catalyst as well as a preparation method and application thereof, and relates to the technical field of catalysts. The nitrobenzene hydrogenation composite catalyst provided by the invention comprises active metal Ni and a composite oxide carrier, wherein the composite oxide carrier comprises an M1Ox carrier and an M2Oy carrier; m1 is Mg, Ti, Zn, Zr, Mn, La or Ce; and M2 is Si or Al. The bifunctional composite oxide is used as the carrier, side reaction is effectively avoided through the surface acid-base property of the catalyst, and the hydrogenation activity and selectivity of the catalyst are remarkably improved. The metal Ni is combined with the oxide on the surface of the carrier, so that the dispersity and stability of Ni are improved, the deactivation rate of the catalyst is reduced, and the service life is prolonged. The catalyst realizes preparation of aniline through continuous liquid-phase hydrogenation of nitrobenzene under mild conditions, and has a good industrial application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly relates to a nitrobenzene hydrogenation composite catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Aniline is one of the most important amine substances and is widely used in the preparation of products such as dye intermediate synthesis, pesticides, and rubber additives. More than 300 chemicals can be synthesized using aniline as a raw material. In the dye industry, aniline is used to produce products such as ink blue, phthalocyanine red, and aniline black; in the pesticide industry, aniline is used to produce various insecticides and fungicides, such as DDV, nitrofen, and pretilachlor; in the rubber industry, aniline is an important raw material for manufacturing rubber additives such as MDI, antioxidant A, antioxidant D, antioxidant RD, and antioxidant 4010. In addition, aniline is also used to manufacture drugs, resins, and other chemical products, demonstrating its wide application and importance in the chemical industry.

[0003] The hydrogenation reduction method usually involves a hydrogenation reaction of nitrobenzene raw materials with hydrogen under the promotion of a nano-metal catalyst, generating aniline through multiple intermediates. Common catalysts include copper-based, nickel-based, and noble metal-based catalysts.

[0004] Patent CN 200910034216.9 reports a nano-copper catalyst supported on a macroporous microsphere carrier, which exhibits excellent activity and stability in the process of hydrogenating nitrobenzene in a fluidized bed to produce aniline. However, copper-based catalysts usually have problems such as high reaction temperature, many side reactions, and easy deactivation, and are only suitable for fluidized bed reactors with complex operations.

[0005] Nickel-based catalysts have advantages such as high hydrogenation activity, easy availability of raw materials, and simple preparation process, and are widely used in the reaction of hydrogenating nitrobenzene to produce aniline. They are one of the most promising hydrogenation catalysts, but mainly use batch autoclave reactors, increasing the complexity and risk coefficient of the process. The main reason is that although nickel-based catalysts have high catalytic activity, their stability in the reaction system needs to be improved, and regeneration is difficult, making it difficult to meet the requirements of continuous flow fixed bed reactors for catalysts. Although noble metal catalysts are also used in the hydrogenation reaction of nitrobenzene and its derivatives, due to the scarcity and high price of noble metals, their large-scale application is severely restricted.

[0006] Patent CN 201410750860.7 reports a preparation method of a nitrobenzene catalytic hydrogenation catalyst. The preparation steps of the catalyst include: 1. Adding bentonite to an aqueous solution of a soluble nickel salt to prepare Ni-intercalated bentonite; 2. Dispersing Ni-intercalated bentonite and CH 3 COONa in deionized water, and adding NaH 2 PO 2A mixed solution of [substance] and NaOH was reacted until no more bubbles were produced in the solution. Through the electrostatic attraction between Ni and P, P was inserted into the interlayer of the bentonite. The product was subjected to suction filtration, and the filter cake was washed with ammonia water, deionized water, and absolute ethanol, and sealed with alcohol for later use, obtaining a catalyst for the catalytic hydrogenation of nitrobenzene. A bentonite catalyst intercalated with amorphous Ni-P alloy was prepared. The preparation process was simple, with high catalytic activity, stable performance, and a relatively long catalyst life. However, since the carrier used was natural bentonite, it was impossible to adjust the composition of the carrier, and thus it could not be specifically used for different catalytic hydrogenation reactions of nitrobenzene to improve the conversion rate of nitrobenzene and the selectivity of aniline under different reaction conditions.

[0007] Therefore, how to provide a nitrobenzene hydrogenation composite catalyst that can achieve free adjustment of the carrier to be suitable for different reaction conditions, and has high activity, high selectivity, and low cost is particularly important for realizing the efficient catalytic hydrogenation of nitrobenzene to aniline. Summary of the Invention

[0008] To solve the above problems, the present invention provides a nitrobenzene hydrogenation composite catalyst, its preparation method and application. The catalyst of the present invention can realize the preparation of a composite oxide-supported nickel catalyst with high dispersion, good stability, and excellent hydrogenation performance by adjusting the ratio of different types of carriers and strictly defining the key parameters in the preparation process.

[0009] The nitrobenzene hydrogenation composite catalyst of the present invention comprises 30% - 70% of active metal Ni, and the balance is a composite oxide carrier.

[0010] Further, the composite oxide carrier comprises M 1 O x carrier and M 2 O y carrier.

[0011] Further, the M 1 is Mg, Ti, Zn, Zr, Mn, La or Ce.

[0012] Further, the M 2 is Si or Al.

[0013] Further, x ≤ 2 and y ≤ 3.

[0014] Further, by weight percentage, the content of M 1 O x is 5% - 50%. Preferably, by weight percentage, the content of M 1 O x in the carrier is 20%.

[0015] The present invention also provides a method for preparing the nitrobenzene hydrogenation composite catalyst, which specifically includes the following steps:

[0016] S1. Accurately weigh M 1 O x carrier precursor, dissolve it in deionized water to obtain a salt solution of M 1 ;

[0017] S2. Under vigorous stirring, add a calculated amount of M 1 carrier to the salt solution of M 2 O y , stir and disperse at room temperature to obtain a suspension;

[0018] S3. Dropwise add sodium hydroxide solution to the suspension until pH > 9, then stand for aging. After aging is completed, filter, wash until the filtrate pH = 7, then dry, calcine, and cool to obtain a composite oxide carrier;

[0019] S4. Dropwise add sodium carbonate solution to the nickel salt solution until pH > 9, add the composite oxide carrier to the nickel salt solution, stand for aging. After aging is completed, filter, wash until the filtrate pH = 7, then dry, calcine, and cool to obtain the nitrobenzene hydrogenation composite catalyst.

[0020] Further, the M 1 O x carrier precursor is one or more of MgSO 4 ·7H 2 O, TiOSO 4 , Zn(NO 3 ) 2 ·6H 2 O, Zr(NO 3 ) 4 ·5H 2 O, Mn(NO 3 ) 2 ·4H 2 O, La(NO 3 ) 3 ·6H 2 O, Ce(NO 3 ) 3 ·6H 2 O.

[0021] Further, the nickel salt is one or more of nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate.

[0022] Further, the concentration of the M 1 salt solution is 10 wt%.

[0023] Further, the concentration of the sodium hydroxide solution is 5 mol / L.

[0024] Further, the aging temperature of S3 is room temperature and the aging time is 4 h.

[0025] Further, the drying temperature of S3 is 110°C and the drying time is 10 h.

[0026] Further, the calcination temperature of S3 is 400°C to 800°C and the calcination time is 2 to 10 h. Preferably, the calcination temperature of S3 is 600°C and the calcination time is 4 h.

[0027] Further, the concentration of the nickel salt solution is 10 wt%.

[0028] Further, the concentration of the sodium carbonate solution is 5 mol / L.

[0029] Further, the aging temperature of S4 is 70°C and the aging time is 4 h.

[0030] Further, the drying temperature of S4 is 110°C and the drying time is 10 h.

[0031] Further, the calcination temperature of S4 is 400°C to 800°C and the calcination time is 2 to 10 h.

[0032] Another object of the present invention is to provide the application of the nitrobenzene hydrogenation composite catalyst in the continuous fixed-bed hydrogenation of nitrobenzene to aniline.

[0033] Further, the reaction temperature is 40°C to 120°C and the hydrogen reaction pressure is 0.5 to 8 MPa.

[0034] Further, in the continuous fixed-bed reactor, the mass space velocity of nitrobenzene is 0.5 to 5 h -1 , and the molar ratio of hydrogen to nitrobenzene is (10 to 50):1. Preferably, in the continuous fixed-bed reactor, the mass space velocity of nitrobenzene is 3 h -1 , and the molar ratio of hydrogen to nitrobenzene is 30:1.

[0035] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0036] The present invention uses a bifunctional composite oxide as a carrier, which can adjust the surface acidity and basicity of nitrobenzene hydrogenation according to different reaction conditions, is beneficial to the adsorption of substrates and the desorption of target products, effectively avoids the occurrence of side reactions, and significantly improves the hydrogenation activity and product selectivity of the catalyst.

[0037] In the present invention, the metal Ni and the oxide on the surface of the support are combined through ionic bonds and covalent bonds, enabling a strong interaction between the active metal and the composite oxide support. This is beneficial for improving the dispersion of Ni and increasing the stability of Ni under specific reaction conditions, effectively reducing the deactivation rate of the catalyst, solving the problem of poor stability of traditional nickel-based catalysts in the hydrogenation reaction of nitrobenzene, and significantly increasing the service life of the catalyst.

[0038] The catalyst of the present invention has high catalytic performance and good stability in the reaction of hydrogenating nitrobenzene to aniline, and can realize the continuous liquid-phase hydrogenation of nitrobenzene to produce aniline under mild conditions, having very good industrial application prospects. Brief Description of the Drawings

[0039] The present invention will be further described below in conjunction with the drawings.

[0040] Figure 1 It is a graph showing the change trends of the conversion rate and selectivity of the catalyst in Example 1 in the hydrogenation reaction of nitrobenzene;

[0041] Figure 2 It is a graph showing the change trends of the conversion rate and selectivity of the catalyst in Comparative Example 1 in the hydrogenation reaction of nitrobenzene. Detailed Embodiments

[0042] The present invention provides a composite catalyst for hydrogenating nitrobenzene, and the catalyst comprises 30% - 70% of active metal Ni, and the balance is a composite oxide support.

[0043] The present invention limits the content of the active metal Ni in the catalyst, and the activity of the catalyst is directly affected by the content of the active metal Ni. The range of 30% - 70% ensures that the catalyst has sufficient active sites, thereby increasing the reaction rate and conversion rate. An excessively high content of the active metal Ni will cause the aggregation of active centers on the catalyst surface, and lead to a decrease in mechanical strength and thermal stability, and is prone to sintering and deactivation, thus affecting the catalytic performance. And the range of 30% - 70% helps to balance the activity and stability, reduce the production cost of the catalyst, and at the same time maintain high catalytic performance. An appropriate amount of the active metal Ni helps to disperse evenly on the surface of the support, avoiding the aggregation phenomenon, thereby improving the effective utilization rate of the catalyst.

[0044] In one embodiment, the composite oxide support comprises M 1 O x support and M 2 O y support.

[0045] In one embodiment, the M 1 is Mg, Ti, Zn, Zr, Mn, La or Ce.

[0046] In one embodiment, the M2 is Si or Al.

[0047] In one embodiment, x ≤ 2 and y ≤ 3.

[0048] In one embodiment, by weight percentage, the content of M 1 O x in the catalyst is 5% to 50%.

[0049] In one embodiment, by weight percentage, the content of M 1 O x in the catalyst is 20%.

[0050] The present invention also defines that the content of M 1 O x is 5% to 50%. The purpose is to ensure the content of the active center Ni in the catalyst, so as to have sufficient active sites, which is beneficial to improving the catalytic activity, while avoiding the decrease of mechanical strength and thermal stability caused by too high content of the active metal Ni. An appropriate content of M 1 O x helps to disperse evenly on the surface of the carrier, avoid agglomeration, and improve the effective utilization rate of the catalyst. In addition, such a content range can also reduce the production cost of the catalyst and maintain high catalytic performance. Therefore, the content range of 5% to 50% of M 1 O x is a reasonable choice for optimizing the performance of the catalyst.

[0051] In addition, the limitation of the content of M 1 O x in the present invention implicitly defines the ratio of M 1 O x and M 2 O y , and further optimizes the performance of the catalyst. The present invention optimizes the surface acidity and basicity of the catalyst by adjusting the ratio of M 1 O x and M 2 O y , which is beneficial to the adsorption of the substrate and the desorption of the target product, effectively avoids the occurrence of side reactions, and significantly improves the hydrogenation activity and product selectivity of the catalyst. In addition, an appropriate ratio can enhance the interaction between the active metal Ni and the composite oxide carrier, improve the dispersion and stability of Ni, and reduce the deactivation rate of the catalyst. A reasonable ratio can also improve the mechanical strength and thermal stability of the catalyst, extend the service life of the catalyst, and reduce the production cost at the same time. Therefore, defining the ratio of M 1 O x and M 2 O y is a necessary choice for optimizing the performance of the catalyst of the present invention.

[0052] The present invention also provides a method for preparing the nitrobenzene hydrogenation composite catalyst, which specifically includes the following steps:

[0053] S1. Accurately weigh the M 1 O x carrier precursor, dissolve it in deionized water to obtain the salt solution of M 1 ;

[0054] S2. Under vigorous stirring, add a calculated amount of the M 1 carrier to the salt solution of M 2 O y , stir and disperse at room temperature to obtain a suspension;

[0055] S3. Dropwise add sodium hydroxide solution to the suspension until pH>9, then stand for aging. After aging is completed, filter, wash until the filtrate pH = 7, then dry, calcine, and cool to obtain a composite oxide carrier;

[0056] S4. Dropwise add sodium carbonate solution to the nickel salt solution until pH>9, add the composite oxide carrier to the nickel salt solution, stand for aging. After aging is completed, filter, wash until the filtrate pH = 7, then dry, calcine, and cool to obtain the nitrobenzene hydrogenation composite catalyst.

[0057] In one embodiment, the M 1 O x carrier precursor is one or more of MgSO 4 ·7H 2 O, TiOSO 4 , Zn(NO 3 ) 2 ·6H 2 O, Zr(NO 3 ) 4 ·5H 2 O, Mn(NO 3 ) 2 ·4H 2 O, La(NO 3 ) 3 ·6H 2 O, Ce(NO 3 ) 3 ·6H 2 O.

[0058] In one embodiment, the nickel salt is one or more of nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate.

[0059] In one embodiment, the concentration of the M 1 salt solution is 10 wt%.

[0060] The present invention ensures that M is limited by 1 the concentration of the salt solution (10 wt%) to ensure that the salt of M 1 completely dissolves in deionized water to form a uniform solution, avoiding precipitation or crystallization phenomena caused by too high a concentration, and also avoiding operation difficulties or incomplete reactions caused by too high or too low a concentration. And the appropriate concentration helps to fully react with the M 2 O y support and sodium hydroxide solution in subsequent steps, ensuring that the resulting composite oxide support has good dispersibility and uniformity.

[0061] In one embodiment, the concentration of the sodium hydroxide solution is 5 mol / L.

[0062] The present invention limits the concentration of the sodium hydroxide solution to ensure the controllability and consistency of the reaction conditions. Specifically, the concentration of the sodium hydroxide solution directly affects the pH value of the solution. Controlling the pH value within a specific range can make the reaction proceed smoothly and avoid the occurrence of side reactions. The appropriate concentration can also ensure a moderate reaction rate, neither too fast to cause the reaction to get out of control nor too slow to affect the production efficiency. In addition, a specific concentration of the sodium hydroxide solution helps to form a uniform precipitate, thus ensuring the uniformity and stability of the final catalyst. Strictly controlling the concentration of the sodium hydroxide solution can ensure the high efficiency and stability of the catalyst.

[0063] In one embodiment, the aging temperature of S3 is room temperature and the aging time is 4 h.

[0064] The present invention ensures that the formation process of the composite oxide support can proceed under optimal conditions by limiting the aging temperature and aging time, thereby obtaining a catalyst with ideal physical and chemical properties. Specifically, appropriate aging temperature and time can promote the full reaction of the precursor and the formation of the crystal structure, ensuring the uniformity and stability of the support. If the aging temperature is too low or the time is insufficient, the reaction may be incomplete and the resulting support structure may be unstable; while if the temperature is too high or the time is too long, overreaction or destruction of the support crystal structure may occur. Therefore, by strictly controlling the aging temperature and time, the performance of the catalyst can be optimized, and its efficiency and lifespan in practical applications can be improved.

[0065] In one embodiment, the drying temperature of S3 is 110 °C and the drying time is 10 h.

[0066] In one embodiment, the calcination temperature of S3 is 400 °C to 800 °C and the calcination time is 2 to 10 h.

[0067] In one embodiment, the calcination temperature of S3 is 600 °C and the calcination time is 4 h.

[0068] The present invention simultaneously defines that the drying temperature, drying time, calcination temperature, and calcination time have a significant impact on the combination of the active metal Ni and the support. Appropriate drying and calcination conditions can ensure that the support forms a uniform and stable structure, thereby providing more active sites and better dispersion. This helps the active metal Ni to form strong interactions with the oxides on the support surface through ionic bonds and covalent bonds, improving the dispersion and stability of the active metal, reducing the deactivation rate of the catalyst, and ultimately enhancing the overall performance and service life of the catalyst. By strictly controlling these conditions, the combination of the active metal Ni and the support can be optimized to ensure the high efficiency and stability of the catalyst in practical applications.

[0069] In one embodiment, the concentration of the nickel salt solution is 10 wt%.

[0070] In one embodiment, the concentration of the sodium carbonate solution is 5 mol / L.

[0071] The present invention ensures that the reaction conditions can be precisely controlled during the preparation process by defining the concentration of the sodium carbonate solution, promoting the uniform deposition of the active metal Ni and the stable formation of the support. An appropriate concentration of sodium carbonate can effectively adjust the pH value of the solution, ensure a moderate reaction rate, avoid too fast or too slow reaction rates, thereby preventing the occurrence of side reactions and the formation of non-uniform precipitation. By strictly controlling the concentration of the sodium carbonate solution, the structure and performance of the catalyst can be optimized, improving its efficiency and stability in practical applications.

[0072] In one embodiment, the aging temperature of S4 is 70 °C and the aging time is 4 h.

[0073] In one embodiment, the drying temperature of S4 is 110 °C and the drying time is 10 h.

[0074] In one embodiment, the calcination temperature of S4 is 400 °C to 800 °C and the calcination time is 2 to 10 h.

[0075] Another object of the present invention is to provide the application of the nitrobenzene hydrogenation composite catalyst in the continuous fixed-bed hydrogenation of nitrobenzene to aniline reaction.

[0076] In one embodiment, the reaction temperature is 40 °C to 120 °C and the hydrogen reaction pressure is 0.5 to 8 MPa.

[0077] In one embodiment, in the continuous fixed-bed reactor, the mass space velocity of nitrobenzene is 0.5 to 5 h -1 , and the molar ratio of hydrogen to nitrobenzene is (10 to 50):1.

[0078] In one embodiment, in the continuous fixed-bed reactor, the mass space velocity of nitrobenzene is 3 h -1, the molar ratio of hydrogen to nitrobenzene is 30:1.

[0079] Compared with the traditional continuous fixed-bed hydrogenation process of nitrobenzene to aniline, the reaction conditions applicable to the catalyst of the present invention are more flexible and can be adjusted according to specific requirements, thereby optimizing the reaction efficiency and product selectivity, ensuring sufficient hydrogen supply, promoting the complete hydrogenation reaction of nitrobenzene, reducing the generation of by-products, reducing the deactivation of the catalyst, and prolonging the service life of the catalyst. It helps to improve the reaction efficiency, reduce energy consumption and costs, and at the same time reduce environmental pollution.

[0080] The technical solutions provided by the present invention will be further described below in conjunction with embodiments.

[0081] Example 1

[0082] A nitrobenzene hydrogenation composite catalyst, calculated by mass fraction, the content of active metal Ni in the catalyst is 50%, the content of MgO is 20%, and the balance is SiO 2 .

[0083] The preparation method of the nitrobenzene hydrogenation composite catalyst is as follows:

[0084] S1. Accurately weigh 122.32 g of MgSO 4 ·7H 2 O and dissolve it in 1100 mL of deionized water. After stirring and dissolving, add 30 g of SiO 2 powder to this solution. After stirring at room temperature for 30 min, gradually add 5 mol / L sodium hydroxide solution until the pH of the above suspension is 9. After aging at room temperature for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain the MgO-SiO 2 composite oxide support.

[0085] S2. Catalyst preparation: Accurately weigh 247.73 g of Ni(NO 3 ) 2 ·6H 2 O, add 2200 mL of deionized water to obtain a 10% nickel salt solution, and then gradually add 5 mol / L sodium carbonate solution to it until the pH of the solution is 9. Then add the above MgO-SiO 2 composite oxide support to it, quickly raise the temperature to 70 °C and age for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain the nitrobenzene hydrogenation composite catalyst 50% Ni / MgO-SiO 2 .

[0086] Performance evaluation: The shaped catalyst 50% Ni / MgO-SiO after calcination with a particle size of 20-60 mesh 2Loaded into a high-pressure fixed-bed flow reactor, reduced in a hydrogen gas stream at 500 °C for 4 h, and started feeding after the temperature dropped to the reaction temperature. The reaction temperature was 80 °C, the raw material concentration was a 50% nitrobenzene-methanol solution, the hydrogen reaction pressure was 4.0 MPa, and the mass space velocity of nitrobenzene was 3 h -1 , and the molar ratio of hydrogen to nitrobenzene was 30.

[0087] Example 2

[0088] A nitrobenzene hydrogenation composite catalyst, in terms of mass fraction, the content of active metal Ni in the catalyst is 30%, and the content of TiO 2 support is 50%, and the balance is SiO 2 support.

[0089] The preparation method of the nitrobenzene hydrogenation composite catalyst is as follows:

[0090] S1. Support preparation: Accurately weigh 100.13 g of TiOSO 4 dissolved in 900 mL of deionized water. After stirring and dissolving, add 20 g of SiO 2 powder to the solution. After stirring at room temperature for 30 min, gradually add 5 mol / L sodium hydroxide solution until the pH of the above suspension is 9. After aging at room temperature for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 800 °C for 2 h to obtain TiO 2 -SiO 2 composite oxide support.

[0091] S2. Catalyst preparation: Accurately weigh 134.36 g of NiSO 4 ·6H 2 O, add 1200 mL of deionized water to obtain a 10% nickel salt solution, and then gradually add 5 mol / L sodium carbonate solution until the pH of the solution is 9. Then add the above TiO 2 -SiO 2 support to it, quickly raise the temperature to 70 °C and age for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 800 °C for 2 h to obtain the nitrobenzene hydrogenation composite catalyst 30% Ni / TiO 2 -SiO 2 .

[0092] Performance evaluation: The same as in Example 1.

[0093] Example 3

[0094] A nitrobenzene hydrogenation composite catalyst, in terms of mass fraction, the content of active metal Ni in the catalyst is 70%, the content of ZnO support is 5%, and the balance is SiO 2 support.

[0095] The preparation method of the nitrobenzene hydrogenation composite catalyst is as follows:

[0096] S1. Carrier preparation: Accurately weigh 18.28 g of Zn(NO 3 ) 2 ·6H 2 O and dissolve it in 160 mL of deionized water. After stirring and dissolving, add 25 g of SiO 2 powder to this solution. After stirring at room temperature for 30 min, gradually add 5 mol / L sodium hydroxide solution until the pH of the above suspension is 9. After aging at room temperature for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 400 °C for 10 h to obtain the ZnO-SiO 2 composite oxide carrier.

[0097] S2. Catalyst preparation: Accurately weigh 283.49 g of NiCl 2 ·6H 2 O, add 2550 mL of deionized water to obtain a 10% nickel salt solution, and then gradually add 5 mol / L sodium carbonate solution to it until the pH of the solution is 9. Then add the above ZnO-SiO 2 carrier to it, quickly raise the temperature to 70 °C and age for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 400 °C for 10 h to obtain the nitrobenzene hydrogenation composite catalyst 70% Ni / ZnO-SiO 2 .

[0098] Performance evaluation: The same as in Example 1.

[0099] Example 4

[0100] A nitrobenzene hydrogenation composite catalyst. In terms of mass fraction, the content of the active metal Ni in this catalyst is 50%, the content of the ZrO 2 carrier is 20%, and the balance is the SiO 2 carrier.

[0101] The preparation method of the nitrobenzene hydrogenation composite catalyst is as follows:

[0102] S1. Carrier preparation: Accurately weigh 69.68 g of Zr(NO 3 ) 4 ·5H 2 O and dissolve it in 630 mL of deionized water. After stirring and dissolving, add 30 g of SiO 2The powder was stirred at room temperature for 30 min, and then a 5 mol / L sodium hydroxide solution was added dropwise until the pH of the above suspension was 9. After aging at room temperature for 4 h, it was filtered and washed until the pH of the filtrate was 7, dried at 110 °C for 10 h, and calcined at 600 °C for 4 h to obtain ZrO 2 -SiO 2 composite oxide support.

[0103] S2. Catalyst preparation: Accurately weigh 212.00 g of Ni(OAc) 2 ·4H 2 O, add 1900 mL of deionized water to obtain a 10% nickel salt solution, and then add a 5 mol / L sodium carbonate solution dropwise thereto until the pH of the solution is 9. Then add the above ZrO 2 -SiO 2 support thereto, quickly raise the temperature to 70 °C and age for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain a nitrobenzene hydrogenation composite catalyst 50% Ni / ZrO 2 -SiO 2 .

[0104] Performance evaluation: The same as in Example 1.

[0105] Example 5

[0106] A nitrobenzene hydrogenation composite catalyst, in terms of mass fraction, the content of the active metal Ni in the catalyst is 50%, and the content of the MnO 2 support is 20%, and the balance is Al 2 O 3 support.

[0107] The preparation method of the nitrobenzene hydrogenation composite catalyst is as follows:

[0108] S1. Support preparation: Accurately weigh 57.74 g of Mn(NO 3 ) 2 ·4H 2 O and dissolve it in 520 mL of deionized water. After stirring and dissolving, add 30 g of Al 2 O 3 powder to this solution. After stirring at room temperature for 30 min, add a 5 mol / L sodium hydroxide solution dropwise until the pH of the above suspension is 9. After aging at room temperature for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain MnO 2 -Al 2 O 3 composite oxide support.

[0109] S2. Catalyst preparation: Accurately weigh 247.73 g of Ni(NO3 ) 2 ·6H 2 O, add 2200 mL of deionized water to obtain a 10% nickel salt solution, then gradually add 5 mol / L sodium carbonate solution dropwise thereto until the pH of the solution = 9, and then add the above-mentioned MnO 2 -Al 2 O 3 support thereto, quickly heat up to 70 °C and age for 4 h, filter and wash until the pH of the filtrate = 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain the nitrobenzene hydrogenation composite catalyst 50% Ni / MnO 2 -Al 2 O 3 .

[0110] Performance evaluation: The same as in Example 1.

[0111] Example 6

[0112] A nitrobenzene hydrogenation composite catalyst, in terms of mass fraction, the content of the active metal Ni in the catalyst is 50%, and the La 2 O 3 support content is 20%, and the balance is Al 2 O 3 support.

[0113] The preparation method of the nitrobenzene hydrogenation composite catalyst is as follows:

[0114] S1. Support preparation: Accurately weigh 53.16 g of La(NO 3 ) 3 ·6H 2 O and dissolve it in 480 mL of deionized water. After stirring and dissolving, add 30 g of Al 2 O 3 powder thereto. After stirring at room temperature for 30 min, gradually add 5 mol / L sodium hydroxide solution dropwise until the pH of the above suspension = 9. After aging at room temperature for 4 h, filter and wash until the pH of the filtrate = 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain La 2 O 3 -Al 2 O 3 composite oxide support.

[0115] S2. Catalyst preparation: Accurately weigh 247.73 g of Ni(NO 3 ) 2 ·6H 2 O, add 2200 mL of deionized water to obtain a 10% nickel salt solution, then gradually add 5 mol / L sodium carbonate solution dropwise thereto until the pH of the solution = 9, and then add the above-mentioned La 2 O3 -Al 2 O 3 The carrier was added thereto, and the temperature was rapidly raised to 70 °C for aging for 4 h, filtered and washed until the pH of the filtrate was 7, dried at 110 °C for 10 h, and calcined at 600 °C for 4 h to obtain a nitrobenzene hydrogenation composite catalyst 50% Ni / La 2 O 3 -Al 2 O 3 .

[0116] Performance evaluation: The same as in Example 1

[0117] Example 7

[0118] A nitrobenzene hydrogenation composite catalyst, in terms of mass fraction, the content of the active metal Ni in the catalyst is 50%, CeO 2 The carrier content is 20%, and the balance is Al 2 O 3 carrier

[0119] The preparation method of the nitrobenzene hydrogenation composite catalyst is as follows

[0120] S1. Carrier preparation: Accurately weigh 50.46 g of Ce(NO 3 ) 3 ·6H 2 O and dissolve it in 450 mL of deionized water. After stirring and dissolving, add 30 g of Al 2 O 3 powder thereto, stir at room temperature for 30 min, and then dropwise add 5 mol / L sodium hydroxide solution until the pH of the above suspension is 9. After aging at room temperature for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain CeO 2 -Al 2 O 3 composite oxide carrier

[0121] S2. Catalyst preparation: Accurately weigh 247.73 g of Ni(NO 3 ) 2 ·6H 2 O, add 2200 mL of deionized water to obtain a 10% nickel salt solution, and then dropwise add 5 mol / L sodium carbonate solution thereto until the pH of the solution is 9. Then add the above CeO 2 -Al 2 O 3 carrier thereto, rapidly raise the temperature to 70 °C for aging for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain a nitrobenzene hydrogenation composite catalyst 50% Ni / CeO 2 -Al2 O 3 。

[0122] Performance evaluation: the same as that of Example 1.

[0123] Example 8

[0124] The catalyst is the same as that of Example 1, and the performance evaluation is as follows:

[0125] 50% Ni / MgO-SiO shaped catalyst after calcination with 20-60 mesh 2 was loaded into a high-pressure fixed-bed flow reactor and reduced in a hydrogen stream at 500 °C for 4 h. After the temperature dropped to the reaction temperature, feeding was started. The reaction temperature was 40 °C, the raw material concentration was a 50% nitrobenzene-methanol solution, the hydrogen reaction pressure was 4.0 MPa, and the mass space velocity of nitrobenzene was 0.5 h -1 , and the molar ratio of hydrogen to nitrobenzene was 30.

[0126] Example 9

[0127] The catalyst is the same as that of Example 1, and the performance evaluation is as follows:

[0128] 50% Ni / MgO-SiO shaped catalyst after calcination with 20-60 mesh 2 was loaded into a high-pressure fixed-bed flow reactor and reduced in a hydrogen stream at 500 °C for 4 h. After the temperature dropped to the reaction temperature, feeding was started. The reaction temperature was 120 °C, the raw material concentration was a 50% nitrobenzene-methanol solution, the hydrogen reaction pressure was 4.0 MPa, and the mass space velocity of nitrobenzene was 5 h -1 , and the molar ratio of hydrogen to nitrobenzene was 30.

[0129] Example 10

[0130] The catalyst is the same as that of Example 1, and the performance evaluation is as follows:

[0131] 50% Ni / MgO-SiO shaped catalyst after calcination with 20-60 mesh 2 was loaded into a high-pressure fixed-bed flow reactor and reduced in a hydrogen stream at 500 °C for 4 h. After the temperature dropped to the reaction temperature, feeding was started. The reaction temperature was 80 °C, the raw material concentration was a 50% nitrobenzene-methanol solution, the hydrogen reaction pressure was 0.5 MPa, and the mass space velocity of nitrobenzene was 3 h -1 , and the molar ratio of hydrogen to nitrobenzene was 50.

[0132] Example 11

[0133] The catalyst is the same as that of Example 1, and the performance evaluation is as follows:

[0134] 50% Ni / MgO-SiO shaped catalyst after calcination with 20-60 mesh 2Loaded into a high-pressure fixed-bed flow reactor, reduced in a hydrogen gas stream at 500 °C for 4 h, and after the temperature dropped to the reaction temperature, feeding was started. The reaction temperature was 80 °C, the raw material concentration was a 50% nitrobenzene-methanol solution, the hydrogen reaction pressure was 8.0 MPa, and the mass space velocity of nitrobenzene was 3 h -1 , and the molar ratio of hydrogen to nitrobenzene was 10.

[0135] Example 12

[0136] A nitrobenzene hydrogenation composite catalyst, in terms of mass fraction, the content of active metal Ni in the catalyst is 50%, the content of MgO support is 10%, and the balance is SiO 2 support.

[0137] S1. Preparation of the support: Accurately weigh 61.16 g of MgSO 4 ·7H 2 O and dissolve it in 550 mL of deionized water. After stirring and dissolving, add 40 g of SiO 2 powder to the solution. After stirring at room temperature for 30 min, gradually add 5 mol / L sodium hydroxide solution until the pH of the above suspension is 9. After aging at room temperature for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain a composite oxide support.

[0138] S2. Preparation of the catalyst: The same as in Example 1.

[0139] Performance evaluation: The same as in Example 1.

[0140] Example 13

[0141] A nitrobenzene hydrogenation composite catalyst, in terms of mass fraction, the content of active metal Ni in the catalyst is 50%, the content of MgO support is 40%, and the balance is SiO 2 support.

[0142] S1. Preparation of the support: Accurately weigh 244.64 g of MgSO 4 ·7H 2 O and dissolve it in 2200 mL of deionized water. After stirring and dissolving, add 10 g of SiO 2 powder to the solution. After stirring at room temperature for 30 min, gradually add 5 mol / L sodium hydroxide solution until the pH of the above suspension is 9. After aging at room temperature for 4 h, filter and wash until the pH of the filtrate is 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain a composite oxide support.

[0143] S2. Preparation of the catalyst: The same as in Example 1.

[0144] Performance evaluation: The same as in Example 1.

[0145] Comparative Example 1

[0146] A nitrobenzene hydrogenation composite catalyst, by mass fraction, the content of the active metal Ni in the catalyst is 50%, and the content of the SiO 2 support is 50%.

[0147] Catalyst preparation: Accurately weigh 247.73 g of Ni(NO 3 ) 2 ·6H 2 O, add 2200 mL of deionized water to obtain a 10% nickel salt solution, then gradually add a 5 mol / L sodium carbonate solution dropwise thereto until the pH of the solution = 9, and then add the SiO 2 support thereto, quickly raise the temperature to 70 °C and age for 4 h, filter and wash until the pH of the filtrate = 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain an oxide-supported nickel catalyst 50% Ni / SiO 2 .

[0148] Performance evaluation: The same as in Example 1.

[0149] Comparative Example 2

[0150] A nitrobenzene hydrogenation composite catalyst, by mass fraction, the content of the active metal Ni in the catalyst is 50%, and the content of the Al 2 O 3 support is 50%.

[0151] Catalyst preparation: Accurately weigh 247.73 g of Ni(NO 3 ) 2 ·6H 2 O, add 2200 mL of deionized water to obtain a 10% nickel salt solution, then gradually add a 5 mol / L sodium carbonate solution dropwise thereto until the pH of the solution = 9, and then add the Al 2 O 3 support thereto, quickly raise the temperature to 70 °C and age for 4 h, filter and wash until the pH of the filtrate = 7, dry at 110 °C for 10 h, and calcine at 600 °C for 4 h to obtain an oxide-supported nickel catalyst 50% Ni / Al 2 O 3 .

[0152] Performance evaluation: The same as in Example 1.

[0153] Table 1 Evaluation results

[0154] Project Conversion rate of nitrobenzene (%) Selectivity of aniline (%) Example 1 100 99.6 Example 2 100 96.7 Example 3 100 97.2 Example 4 100 98.9 Example 5 100 97.9 Example 6 100 98.7 Example 7 100 97.8 Example 8 100 98.6 Example 9 100 97.4 Example 10 100 95.3 Example 11 100 96.0 Example 12 100 98.7 Example 13 100 98.2 Comparative Example 1 95.2 90.5 Comparative Example 2 92.9 89.0

[0155] Test Example 1

[0156] The catalysts of Example 1 and Comparative Example 1 were respectively loaded into a high-pressure fixed-bed flow reactor and reduced in a hydrogen stream at 500 °C for 4 h. After the temperature dropped to the reaction temperature, feeding was started. The reaction temperature was 80 °C, the raw material concentration was a 50% nitrobenzene-methanol solution, the hydrogen reaction pressure was 4.0 MPa, and the mass space velocity of nitrobenzene was 3 h -1 , the molar ratio of hydrogen to nitrobenzene was 30, samples were taken and analyzed every 12 h to determine the service life of the catalyst, and the results are as Figure 1 , Figure 2 shown.

[0157] In this article, specific examples are used to elaborate on the principles and implementation modes of the present invention. The description of the above examples is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation modes and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A nitrobenzene hydrogenation composite catalyst, characterized in that: It includes 30% to 70% of active metal Ni, and the remainder is a composite oxide carrier; The composite oxide support includes M1O x Carrier and M2O y Carrier; The M1 is Mg, Ti, Zn, Zr, Mn, La or Ce; and the M2 is Si or Al.

2. The nitrobenzene hydrogenation composite catalyst according to claim 1, characterized in that: In terms of weight percentage, the carrier contains M1O x The content is 5% to 50%.

3. The method for preparing the nitrobenzene hydrogenation composite catalyst according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Accurately weigh M1O x The carrier precursor is dissolved in deionized water to obtain a salt solution of M1; S2, under vigorous stirring, add the calculated amount of M2O to the salt solution of M1 y The carrier is dispersed by stirring at room temperature to obtain a suspension; S3, adding sodium hydroxide solution dropwise to the suspension until pH>9, then standing for aging, filtering after aging, washing until the filtrate pH=7, then drying, roasting, and cooling to obtain a composite oxide support; S4, adding sodium carbonate solution dropwise to the nickel salt solution until pH>9, adding the composite oxide support to the nickel salt solution, standing for aging, filtering after aging, washing until the filtrate pH=7, and then drying, roasting, and cooling to obtain a nitrobenzene hydrogenation composite catalyst.

4. The preparation method according to claim 4, characterized in that: The M1O x The carrier precursor is one or more of MgSO4·7H2O, TiOSO4, Zn(NO3)2·6H2O, Zr(NO3)4·5H2O, Mn(NO3)2·4H2O, La(NO3)3·6H2O, and Ce(NO3)3·6H2O.

5. The preparation method according to claim 3, characterized in that: The nickel salt is one or more of nickel nitrate, nickel sulfate, nickel chloride and nickel acetate.

6. The preparation method according to claim 3, characterized in that: The concentration of the M1 salt solution is 10 wt %.

7. Use of the nitrobenzene hydrogenation composite catalyst according to any one of claims 1 to 2 in the continuous fixed-bed hydrogenation of nitrobenzene to produce aniline.

8. The use according to claim 7, characterized in that: The reaction temperature is 40° C. to 120° C., and the hydrogen reaction pressure is 0.5 to 8 MPa.

9. The use according to claim 7, characterized in that: In the continuous fixed bed reactor, the mass space velocity of nitrobenzene is 0.5 to 5 h -1 , the molar ratio of hydrogen to nitrobenzene is (10~50):

1.

10. The use according to claim 9, characterized in that: In the continuous fixed bed reactor, the mass space velocity of nitrobenzene is 3h -1 , the molar ratio of hydrogen to nitrobenzene is 30:1.

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