Nitro hydrogenation catalyst, preparation method thereof and catalytic hydrogenation preparation method of aniline compounds

Abstract

The present invention provides a nitro hydrogenation catalyst, a preparation method thereof, and a catalytic hydrogenation preparation method for aniline compounds. The preparation method comprises: preparing a zirconium source, a first acid agent, and water to form a zirconium source solution, and adding a first precipitant to the zirconium source solution to obtain a mixed solution A; preparing a cerium source, a second acid agent, and water to form a mixed solution B, and adding the mixed solution B and the second precipitant to the mixed solution A to obtain a mixed solution C; subjecting the mixed solution C to a hydrothermal reaction to obtain a carrier precursor; calcining the carrier precursor to obtain a composite carrier; preparing the composite carrier and water to form a first slurry, and adding a nickel source to the first slurry to obtain a second slurry after mixing; and adding a boron source and a phosphorus source to the second slurry and stirring the reaction to obtain a nitro hydrogenation catalyst. The present invention first prepares a composite zirconium-cerium carrier, then reduces the nickel source with a boron source and a phosphorus source, and deposits the nickel source on the resulting composite zirconium-cerium carrier, thereby obtaining a nitro hydrogenation catalyst with superior performance.

Description

Technical Field

[0001] The present invention relates to the field of organic synthesis, and in particular to a nitro hydrogenation catalyst, a preparation method thereof, and a catalytic hydrogenation preparation method of aniline compounds. Background Art

[0002] Aniline derivatives are important fine chemical intermediates, widely used as raw materials in the production of chemicals such as pharmaceuticals, pesticides, rubber, and dyes. Aniline compounds are often prepared industrially through the reduction of nitroaromatic hydrocarbons, typically through iron powder reduction, alkaline sulfide reduction, electrochemical reduction, transfer hydrogenation, and catalytic hydrogenation. Catalytic hydrogenation, which uses hydrogen as a reducing agent, offers excellent economic and environmental benefits and is a common method for the industrial production of aniline. Common catalysts used for nitro hydrogenation include Raney nickel, precious metals such as palladium, platinum, and ruthenium, as well as nickel-based catalysts supported by zirconium, silicon, and alumina.

[0003] In recent years, with the development of catalytic science, a variety of catalysts for hydrogenation reactions of nitro compounds have emerged. Patent No. CN117983210 A provides a catalyst for the synthesis of o-phenylenediamine from o-nitroaniline, which improves catalytic performance by modifying activated carbon and loading it with palladium and platinum metals. However, this method still uses precious metals, which is costly, and the carrier modification process is relatively complex, making large-scale industrial production difficult. Patent No. CN115709102 A proposes a bimetallic nickel-ruthenium catalyst based on a silica / alumina composite support, prepared by impregnation and calcination. This catalyst shows excellent stability in nitro hydrogenation reactions, but its preparation process is complex, and the use of metallic ruthenium also increases costs. Patent No. CN115414940 A synthesizes a carbon-based metal catalyst via a hydrothermal method and heat treatment. Although the catalyst prepared by this method has certain catalytic activity, the carrier preparation and metal loading process involve multiple chemical reactions, harsh operating conditions, and are not conducive to continuous production. Patent No. CN112569943A describes a nickel-based benzene hydrogenation catalyst prepared by coprecipitation and impregnation using a dual-component support of alumina and silica. While the catalyst exhibits good performance in nitro hydrogenation reactions, the support's single acidity and weak interaction between the active component and the support limit the catalyst's performance and service life.

[0004] In general, although current catalytic technology, especially non-precious metal catalytic materials for the hydrogenation reaction of nitro compounds, has made progress in some aspects, there are still some key issues that need to be addressed:

[0005] First, precious metals are expensive and are mostly used in batch nitro hydrogenation reactions, which are prone to poisoning and do not meet the conditions for continuous operation.

[0006] Secondly, the depth of hydrogenation of nickel-based catalysts supported by alumina and zirconium silicon is limited, and the acidity of the support is single, the interaction between the active component and the support is relatively weak, and the catalytic effect is poor;

[0007] Third, although some crystalline catalytic materials with unique structures and properties have emerged, most of them have few surface active sites and poor stability, resulting in poor catalytic performance and are not conducive to long-term use and industrialization.

[0008] Based on this, how to develop a new catalyst system for the hydrogenation of nitroaromatic compounds that can not only significantly reduce production costs and simplify the production process, but also be suitable for continuous production processes while maintaining the high efficiency and selectivity of the reaction is one of the important technical problems that need to be solved in this field. Summary of the Invention

[0009] The main purpose of the present invention is to provide a nitro hydrogenation catalyst, a preparation method thereof, and a catalytic hydrogenation preparation method for aniline compounds, so as to solve the problem that the catalyst system in the prior art cannot achieve catalytic hydrogenation of nitroaromatic compounds to prepare aniline compounds with high conversion rate and high selectivity.

[0010] To achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing a nitro hydrogenation catalyst, comprising: step S1, preparing a zirconium source, a first acid agent and water into a zirconium source solution, and adding a first precipitant to the zirconium source solution to obtain a mixed solution A with a pH of 8.5-9.0; step S2, preparing a cerium source, a second acid agent and water into a mixed solution B, and adding the mixed solution B and the second precipitant to the mixed solution A to obtain a mixed solution C with a pH of 6.8-7.2; step S3, subjecting the mixed solution C to a hydrothermal reaction to obtain a carrier precursor; and subjecting the carrier precursor to a calcination treatment to obtain a composite carrier; step S4, preparing the composite carrier and water into a first slurry, and adding a nickel source to the first slurry to obtain a second slurry after mixing; and step S5, adding a boron source and a phosphorus source to the second slurry at 0±5°C and stirring the reaction so that the boron source, phosphorus source and nickel source are deposited on the composite carrier to form an amorphous alloy, thereby obtaining a nitro hydrogenation catalyst.

[0011] Furthermore, the molar ratio of the zirconium source to the cerium source is 1:(0.2~0.5); and / or the zirconium source is selected from one or more of zirconium nitrate, zirconium oxychloride, zirconium acetate, zirconium sulfate, zirconium carbonate and zirconium chloride; and / or the cerium source is selected from one or more of cerium nitrate, cerium chloride and cerium acetate.

[0012] Furthermore, the total molar amount of the zirconium source and the cerium source is denoted as M1, the total molar amount of the first acid agent and the second acid agent is denoted as M2, M2:M1=1:(75~95); and / or, the first acid agent and the second acid agent are each independently selected from one or more of citric acid, oxalic acid, acetic acid and nitric acid, and the first acid agent and the second acid agent are both added in the form of an acid solution with a molar concentration of 0.08M~0.1M; and / or, the first precipitant and the second precipitant are each independently selected from one or more of sodium hydroxide, sodium carbonate and ammonia water.

[0013] Furthermore, in step S3, the reaction temperature of the hydrothermal reaction is 120°C to 150°C, and the time is 8h to 12h; and / or the calcination temperature of the calcination treatment is 300°C to 400°C, and the calcination treatment is carried out in an inert atmosphere.

[0014] Furthermore, in step S4, the weight ratio of the nickel source to the composite support is (0.6~1.12):1; and / or, the mixing is stirring mixing, and the stirring mixing time is 0.5h~1h; and / or, the nickel source is selected from one or more of nickel nitrate, nickel sulfate hexahydrate and nickel chloride.

[0015] Furthermore, in step S5, the molar ratio of the boron source to the phosphorus source is 1:(1.5~2); and / or, the ratio of the molar amount of the nickel source to the total molar amount of the boron source and the phosphorus source is 1:(2.8~4.0); the boron source is selected from one or more of KBH4, NaBH4 and (CH3COO)3BHNa; and / or, the phosphorus source is selected from one or more of NaH2PO2, H3PO2 and H6NO3P; and / or, the boron source and the phosphorus source are added dropwise, and during the dropwise addition process, step S5 also includes adding an alkaline solution to the second slurry to maintain the pH of the second slurry at 12±0.2; the alkaline solution is selected from one or more of sodium hydroxide solution, sodium carbonate solution and ammonia water.

[0016] A second aspect of the present invention provides a nitro hydrogenation catalyst, which is prepared by the above-mentioned preparation method of the nitro hydrogenation catalyst.

[0017] The third aspect of the present invention provides a method for preparing aniline compounds by catalytic hydrogenation, wherein nitroaromatic compounds and hydrogen are hydrogenated in the presence of the above-mentioned nitro hydrogenation catalyst to obtain aniline compounds.

[0018] Furthermore, before the hydrogenation reaction, the catalytic hydrogenation preparation method of aniline compounds also includes loading a nitro hydrogenation catalyst into a fixed bed and performing an activation treatment, the activation treatment comprising: heating to 100°C~150°C at a heating rate of 10±2°C / min under a hydrogen atmosphere, and keeping the temperature for 2h~3h.

[0019] Furthermore, in the hydrogenation reaction, the feed rate of the nitroaromatic compound is 1.0±0.2 g / min; the feed rate of hydrogen is 20 mL / min~30 mL / min; and the reaction temperature is 50°C~60°C.

[0020] By applying the technical solution of the present invention, a composite zirconium-cerium support is prepared by a precipitation method in a specific order, and then a nickel source is reduced by a boron source and a phosphorus source and deposited on the composite zirconium-cerium support, thereby obtaining a nitro hydrogenation catalyst with superior performance. In the structure of the obtained catalyst, the support and the active component can interact with each other, thereby avoiding the shedding of the active component and improving the adhesion of the active component, thereby causing its catalytic activity and selectivity to increase and extending its service life. Ultimately, the catalyst prepared by the present invention and having a nano-amorphous Ni-B / P component can continuously catalyze the hydrogenation of nitroaromatic compounds using a fixed bed under relatively mild conditions, thereby improving its production conditions and showing a high conversion rate and selectivity for aniline products. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 This is a diagram of the liquid phase test results obtained using Example 3. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0024] As described in the background art, the catalyst system in the prior art has the problem of being unable to achieve catalytic hydrogenation of nitroaromatic compounds to prepare aniline compounds with high conversion rate and high selectivity. In order to solve the above technical problems, the first aspect of the present invention provides a preparation method of a nitro hydrogenation catalyst, comprising: step S1, preparing a zirconium source, a first acid agent and water into a zirconium source solution, and adding a first precipitant to the zirconium source solution to obtain a mixed solution A with a pH of 8.5-9.0; step S2, preparing a cerium source, a second acid agent and water into a mixed solution B, and adding the mixed solution B and the second precipitant to the mixed solution A to obtain a mixed solution C with a pH of 6.8-7.2; step S3, subjecting the mixed solution C to a hydrothermal reaction to obtain a carrier precursor; the carrier precursor is calcined to obtain a composite carrier; step S4, preparing the composite carrier and water into a first slurry, and adding a nickel source to the first slurry to obtain a second slurry after mixing; step S5, adding a boron source and a phosphorus source to the second slurry under the condition of 0±5°C and stirring the reaction so that the boron source, phosphorus source and nickel source are deposited on the composite carrier to form an amorphous alloy, thereby obtaining a nitro hydrogenation catalyst.

[0025] The present invention prepares a composite zirconium-cerium support by a precipitation method, and then reduces a nickel source through a boron source and a phosphorus source, and deposits the nickel source on the composite zirconium-cerium support obtained, thereby obtaining a nitro hydrogenation catalyst with superior performance. Specifically, in step S1, a zirconium source solution is prepared by mixing a zirconium source with a first acid agent and water, and then the zirconium ions react with the first precipitant to form a zirconium-based precursor with a specific morphology and pore size. Subsequently, the cerium source is mixed with a second acid agent and water to form a mixed solution B. When the mixed solution B is added to the mixed solution A having an adjusted pH value together with the cerium source, the deposition of cerium ions on the surface of the zirconium-based precursor is uniform and gradually transitioned, from a low cerium content to a high cerium content region, ultimately forming a cerium-rich surface layer. This process not only increases the electronic activity of the composite support, but also promotes the formation of oxygen vacancies, providing abundant active sites for the deposition of subsequent active components. The mixed liquid C is subjected to a hydrothermal reaction to promote the fusion of zirconium-cerium oxide particles, enhance the stability of the material, and retain the gradient characteristics of the transition layer. The structure of the zirconium-cerium composite support to be formed is further optimized, so that it can form a more compact ZrO2 / CeO2 composite material under high temperature and high pressure environment, creating a stable support with rich active sites for the subsequent deposition of amorphous alloys.

[0026] Then, in step S4, physical mixing is performed to uniformly distribute the nickel ions on the surface of the resulting composite support. Finally, in step S5, a boron source and a phosphorus source are added at low temperature (0±5°C) and stirred for reaction. Boron and phosphorus act as reducing agents and react with the nickel ions to form an amorphous Ni-B / P alloy.

[0027] Furthermore, during this step, low-temperature conditions are selected for alloy deposition, avoiding the formation of a crystalline phase, resulting in the alloy exhibiting short-range order and long-range disorder. This structural characteristic, on the one hand, increases the free energy of the material surface, creating more active sites; on the other hand, the electronic interactions between the B / P atoms and the metallic Ni atoms render the Ni electron-rich and the B / P atoms electron-deficient. This difference in electronic structure contributes to the catalyst's different adsorption capacities for nitrogen and oxygen atoms in nitro compounds, enhancing the catalyst's selectivity and activity for nitro hydrogenation reactions.

[0028] In summary, the preparation method provided by the present invention precisely controls the structure of the zirconium-cerium composite support through sequential precipitation reactions, combined with low-temperature deposition of an amorphous alloy, to construct a nitro hydrogenation catalyst with a unique microstructure. The resulting catalyst structure features a Zr-Ce oxide composite support with a gradient transition layer of cerium content, resulting in a gradient distribution of electronic properties and active sites from the core to the surface. This structural characteristic improves the catalyst's adaptability and catalytic efficiency to different reactants, while also avoiding the problem of active component shedding caused by uneven distribution of cerium and zirconium in traditional co-precipitation methods.

[0029] In particular, the cerium-rich surface of the composite support is rich in oxygen vacancies, which significantly enhance the catalyst's adsorption capacity for nitro compounds, facilitating the stable adsorption and activation of reactants on the catalyst surface, thereby improving the selectivity and efficiency of the hydrogenation reaction. Furthermore, the redox properties of cerium, combined with the stable ZrO2 core, provide a favorable electronic environment for the catalyst. The electron-rich nature of CeO2 promotes electron transfer from reactants to the catalyst, enhancing reactant activation, while the stable ZrO2 framework supports this process, ensuring the long-term stability of the catalyst.

[0030] Furthermore, in the aforementioned preparation method, the amorphous Ni-B / P alloy is essentially nanoscale, with a minimum size of 3 to 5 nm. Its deposition on the cerium-rich surface significantly increases the catalyst's active site density. The synergistic effect of the B / P elements and Ni enhances the catalyst's ability to decompose and adsorb hydrogen and deeply hydrogenate nitro compounds. In other words, the catalyst with this amorphous structure possesses abundant active sites and strong electron mobility, effectively accelerating the nitro hydrogenation reaction while maintaining high selectivity and long-term stability.

[0031] Furthermore, the molar ratio of the zirconium source to the cerium source is 1:(0.2-0.5). Under this molar ratio, cerium ions are more likely to deposit preferentially on the surface of the ZrO2 particles. Due to the reducing properties of cerium ions and their easy conversion between different valence states, they form a more stable transition layer with gradually increasing cerium content on the surface of the zirconium-based material, thereby significantly enhancing the catalyst's adsorption capacity for nitro compounds.

[0032] In several typical embodiments, the zirconium source is selected from one or more of zirconium nitrate, zirconium oxychloride, zirconium acetate, zirconium sulfate, zirconium carbonate, and zirconium chloride; and / or the cerium source is selected from one or more of cerium nitrate, cerium chloride, and cerium acetate. These zirconium and cerium sources can more effectively optimize reaction conditions and improve reaction efficiency, ultimately producing a composite support with a more optimized pore structure and a higher active site density.

[0033] To further enhance the uniformity and stability of the resulting composite support, the total molar weight of the zirconium and cerium sources is designated M1, and the total molar weight of the first and second acid agents is designated M2, with M2:M1 = 1:(75-95). Specifically, a more optimal amount of acid can promote the formation of a highly stable and uniform structure from the composite support precursor during hydrothermal treatment. Furthermore, this amount of acid provides a more precise buffering effect, allowing for more precise control of the rate and depth of cerium ion deposition on the ZrO2 surface. This results in a unique structure characterized by a transition layer with a gradually varying cerium content from the core to the surface, ultimately optimizing the activity of the resulting catalyst.

[0034] And, in the specific use process, the first acid agent and the second acid agent are independently selected from one or more of citric acid, oxalic acid, acetic acid and nitric acid, and the first acid agent and the second acid agent are both added in the form of an acid solution with a molar concentration of 0.08M~0.1M.

[0035] Furthermore, preferably, the first precipitant and the second precipitant are each independently selected from one or more of sodium hydroxide, sodium carbonate, and aqueous ammonia. More preferably, mixed solution B and the second precipitant are added dropwise to mixed solution A at 40° C. to 50° C. Mixing the solutions containing the zirconium source and the cerium source while simultaneously performing the precipitation reaction within a suitable temperature range can further optimize the porosity and surface area of ​​the resulting support, providing more active sites for the subsequent deposition of the amorphous alloy.

[0036] In step S3, the hydrothermal reaction temperature is 120°C to 150°C, and the reaction time is 8 to 12 hours. The temperature and duration of the hydrothermal reaction promote the uniform growth of zirconium-cerium oxide grains, thereby further enhancing the bonding strength between the amorphous alloy and the support. Subsequently, the calcination treatment is preferably performed at a temperature of 300°C to 400°C in an inert atmosphere, thereby further improving the thermal stability of the resulting composite support, promoting the formation of oxygen vacancies on the support surface, and enhancing the activity and stability of the resulting catalyst.

[0037] Furthermore, in step S4, the weight ratio of the nickel source to the composite support is preferably (0.6~1.12):1. This preferred weight ratio more significantly promotes a strong interaction between the metal active component nickel and the support. In particular, when the support contains oxygen vacancies, the oxygen vacancies at the interface of the nickel nanoparticles can significantly enhance the adsorption capacity of the catalyst for reactants, accelerate the charge transfer and activation process, and ultimately improve the efficiency of the catalytic hydrogenolysis reaction, especially the cleavage of the NO bond, thereby achieving a more efficient nitro hydrogenation reaction. In order to ensure more complete contact and uniform dispersion of the nickel source and the composite support, the mixing is preferably stirred, and the stirring time is 0.5h~1h. In practical applications, the nickel source can be selected from one or more of nickel nitrate, nickel sulfate hexahydrate and nickel chloride.

[0038] In step S5, the molar ratio of the boron source to the phosphorus source is preferably 1:(1.5-2); and / or the ratio of the molar amount of the nickel source to the total molar amount of the boron source and the phosphorus source is 1:(2.8-4.0). By optimizing the molar ratios of boron, phosphorus, and nickel, the catalyst structure is further optimized. The B and P elements are evenly distributed in the amorphous alloy, forming a synergistic electronic environment. This results in a more stable electronic state and spatial configuration of the resulting catalyst, achieving efficient cleavage of the NO bond in the p-nitro hydrogenation reaction, while reducing the occurrence of over-hydrogenation side reactions, and improving the output purity and selectivity of aniline derivatives.

[0039] In several typical embodiments, the boron source is selected from one or more of KBH4, NaBH4, and (CH3COO)3BHNa; and / or the phosphorus source is selected from one or more of NaH2PO2, H3PO2, and H6NO3P. In particular, when the boron source is KBH4 and the phosphorus source is NaH2PO2, KBH4, as a strong reducing agent, can more rapidly reduce the nickel salt to metallic nickel while simultaneously introducing boron into the catalyst structure. NaH2PO2, through the introduction of phosphorus, can adjust the catalyst's electronic environment, further enhancing its activity and selectivity.

[0040] Furthermore, it is preferred that the boron source and the phosphorus source are added dropwise, and during the dropwise addition, step S5 further includes adding an alkaline solution to the second slurry to maintain the pH of the second slurry at 12±0.2. This preferred pH regulation, combined with the dropwise addition method, can minimize the agglomeration of each element during precipitation, promote the uniform distribution of the active components, and ultimately form a catalyst with higher activity and high selectivity, thereby improving the yield and purity of the aniline derivative product. In practical applications, the alkaline solution can be selected from one or more of sodium hydroxide solution, sodium carbonate solution and ammonia water, and preferably the molar concentrations of the sodium hydroxide solution and the sodium carbonate solution are each independently 2±0.2M; the mass concentration of the ammonia water is 30±5%.

[0041] A second aspect of the present invention provides a nitro hydrogenation catalyst prepared by the above-mentioned method for preparing the nitro hydrogenation catalyst. The catalyst prepared by the present invention has a unique structure with short-range order and long-range disorder, and thus has more active sites and stronger electron transfer ability than traditional crystalline catalysts. At the same time, the presence of oxygen vacancies not only enhances the adsorption of reactants by the catalyst, but also promotes charge transfer and activation of reactants, especially in the hydrogenation reaction of nitro compounds, playing a decisive role in promoting the cleavage of the N-O bond.

[0042] It should be noted that due to the particularity of the materials field and the limitations of existing testing and characterization methods, it is difficult to conduct a comprehensive quantitative characterization of the complex crystal structure and microstructure of the catalyst obtained above. However, the performance test results show that the catalyst obtained in this application has better catalytic hydrogenation performance, and is particularly suitable for the reaction process of catalytic hydrogenation of nitroaromatic compounds to prepare aniline compounds.

[0043] A third aspect of the present invention provides a method for preparing aniline compounds by catalytic hydrogenation. Aniline compounds are produced by hydrogenating nitroaromatic compounds with hydrogen over the action of a nitro hydrogenation catalyst. The catalyst obtained by the present invention effectively adsorbs and activates reactants during the hydrogenation of nitroaromatics through the synergistic effects of oxygen vacancies and basic sites on the composite support surface and the amorphous Ni-B / P alloy. In particular, the active sites on the catalyst surface efficiently promote electron transfer between nitro groups and hydrogen, accelerating N−O bond cleavage while suppressing potential side reactions such as overhydrogenation and alkylation, ensuring the highly selective production of the final aniline compounds.

[0044] Furthermore, prior to the hydrogenation reaction, the catalytic hydrogenation method for preparing aniline compounds further includes loading a nitro hydrogenation catalyst into a fixed bed and performing an activation treatment. The activation treatment comprises heating the catalyst to 100°C to 150°C at a rate of 10±2°C / min under a hydrogen atmosphere and maintaining the temperature for 2 to 3 hours. During this process, oxygen vacancies on the surface of the nitro hydrogenation catalyst can pre-interact with hydrogen, forming more active hydrogen species, which can then more effectively participate in the subsequent hydrogenation reaction and promote the conversion of nitro compounds.

[0045] In several typical embodiments, during the hydrogenation reaction, the feed rate of the nitroaromatic compound is 1.0±0.2 g / min; the feed rate of hydrogen is 20 mL / min-30 mL / min; and the reaction temperature is 50°C-60°C. Under these preferred conditions, the active sites of the catalyst are fully exposed to the feed nitroaromatics and hydrogen, and its activity and stability are more fully exerted, thereby achieving a more efficient and highly selective nitroaromatic hydrogenation reaction.

[0046] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0047] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0048] Example 1

[0049] A preparation method of a nitro hydrogenation catalyst:

[0050] (1) 33.9 g (0.1 mol) of zirconium nitrate was added to 10 mL of 0.08 M citric acid solution (wherein the molar amount of citric acid was 0.0008 mol) and 100 mL of purified water to obtain a zirconium source solution after dissolution. 1 M sodium hydroxide precipitant was added dropwise to the zirconium source solution at 40°C until the pH reached 8.7 to obtain a mixed solution A.

[0051] (2) Dissolve 6.5 g (0.02 mol) of cerium nitrate (i.e., zirconium source: cerium source = 1:0.2, molar ratio) in 150 mL of purified water, and add 10 mL of 0.08 M citric acid solution (wherein the molar amount of citric acid is 0.0008 mol) to obtain mixed solution B. A 1 M sodium hydroxide precipitant solution was added dropwise to mixed solution A in parallel with mixed solution B. The addition time was controlled to 0.5 h at 40°C, and the pH was maintained at 6.8 to obtain mixed solution C. The ratio of the total molar amount of citric acid to the total molar amount of the zirconium source and cerium source was 1:75.

[0052] (3) The mixed solution C was transferred to a hydrothermal reactor and kept at 120°C for 12 h to carry out a hydrothermal reaction. The composite catalyst support was obtained by filtration and then dried at 90°C for 24 h. The dried solid was calcined at 300°C under nitrogen inert gas to obtain the composite support.

[0053] (4) In a four-necked flask, add 500 mL of purified water and 30 g of the composite support at room temperature. Stir evenly to obtain a first slurry. Then, add 18.6 g (0.102 mol) of nickel nitrate (i.e., nickel source: composite support = 0.62:1, weight ratio) and stir for 0.5 h to obtain a second slurry.

[0054] (5) The second slurry was cooled to 0°C in a circulating water bath, and a solution of 5.5g (0.1mol) KBH4 and a solution of 17.6g (0.2mol) NaH2PO2 were added dropwise under stirring. During this process, the pH was adjusted to 12 with a 2M sodium oxychloride solution. The molar ratio of the boron source to the phosphorus source was 1:2; the molar ratio of the nickel source to the total molar amount of the boron source and the phosphorus source was 1:2.9. After the addition was completed, the reaction was stopped by stirring until no gas was released, and the mixture was filtered. The black precipitate was collected by suction and washed repeatedly with deionized water until the pH was 7, and then washed twice with anhydrous ethanol. The obtained product was dried in a vacuum drying oven at 60°C for 8 h to obtain a nitro hydrogenation catalyst.

[0055] Example 2

[0056] A preparation method of a nitro hydrogenation catalyst:

[0057] (1) 32.2 g (0.1 mol) of zirconium oxychloride was added to 5 mL of 0.08 M oxalic acid solution (molar weight of oxalic acid was 0.0004 mol) and 100 mL of purified water to obtain a zirconium source solution after dissolution. 1 M sodium hydroxide precipitant was added dropwise to the zirconium source solution at 40°C until the pH reached 9.0 to obtain a mixed solution A.

[0058] (2) Dissolve 12.3 g (0.05 mol) of cerium chloride (i.e., zirconium source: cerium source = 1:0.5, molar ratio) in 150 mL of purified water, and add 15 mL of 0.08 M oxalic acid solution (molar amount of oxalic acid is 0.0012 mol) to obtain mixed solution B. At the same time, a 1 M sodium hydroxide precipitant solution was added dropwise to mixed solution A in parallel with mixed solution B. The addition time was controlled to be 1 h at 50 ° C, and the pH was maintained at 7.2 to obtain mixed solution C. The ratio of the molar amount of oxalic acid to the total molar amount of the zirconium source and cerium source was 1:94.

[0059] (3) The mixed solution C was transferred to a hydrothermal reactor and kept warm at 150°C for 8 hours to carry out a hydrothermal reaction. The composite catalyst carrier was obtained by filtration, and dried at 100°C for 12 hours. The dried solid was calcined at 400°C under the protection of nitrogen inert gas to obtain a composite carrier.

[0060] (4) In a four-necked flask, add 500 mL of purified water and 30 g of the composite support at room temperature. Stir evenly to obtain a first slurry. Then, add 33.6 g (0.1279 mol) of nickel sulfate hexahydrate (i.e., nickel source: composite support = 1.12:1, weight ratio) and stir for 1 h to obtain a second slurry.

[0061] (5) The second slurry was cooled to 0°C in a circulating water bath, and 8.6g (0.16mol) of KBH4 solution and 21.11g (0.24mol) of NaH2PO2 solution were added dropwise under stirring. During this process, the pH was adjusted to 12 with a 2M sodium carbonate solution. The molar ratio of the boron source to the phosphorus source was 1:1.5; the molar ratio of the nickel source to the total molar amount of the boron source and the phosphorus source was 1:3.13. After the addition was completed, the reaction was stopped by stirring until no gas was released, and the mixture was filtered. The black precipitate was collected by suction and washed repeatedly with deionized water until the pH was 6.8, and then washed twice with anhydrous ethanol. The obtained product was dried in a vacuum drying oven at 80°C for 6 h to obtain a nitro hydrogenation catalyst.

[0062] Example 3

[0063] A preparation method of a nitro hydrogenation catalyst:

[0064] (1) Dissolve 32.2 g (0.1 mol) of zirconium oxychloride in 10 mL of 0.08 M citric acid solution (molar amount of citric acid is 0.0008 mol) and 100 mL of purified water to obtain a zirconium source solution. Add 30% ammonia precipitant dropwise to the zirconium source solution at 50°C until the pH reaches 8.5 to obtain a mixed solution A.

[0065] (2) Dissolve 12.3 g (0.05 mol) of cerium chloride (i.e., zirconium source: cerium source = 1:0.5, molar ratio) in 150 mL of purified water, and add 10 mL of 0.08 M oxalic acid solution (molar amount of oxalic acid is 0.0008 mol) to obtain mixed solution B. At the same time, a 30% ammonia precipitant was added dropwise to mixed solution A in parallel with mixed solution B. The addition time was controlled at 50°C for 0.8 h, and the pH was maintained at 7.0 to obtain mixed solution C. The ratio of the molar amount of oxalic acid to the total molar amount of the zirconium source and cerium source was 1:94.

[0066] (3) The mixed solution C was transferred to a hydrothermal reactor and kept warm at 130°C for 10 hours to carry out a hydrothermal reaction. The composite catalyst carrier was obtained by filtration, and dried at 100°C for 15 hours. The dried solid was calcined at 350°C under the protection of nitrogen inert gas to obtain a composite carrier.

[0067] (4) Add 500 mL of purified water to a four-necked flask, add 30 g of the composite support at room temperature, and stir evenly to obtain a first slurry. Then, add 30.4 g (0.1277 mol) of nickel chloride hexahydrate (i.e., nickel source: composite support = 1.01:1, weight ratio) and stir for 0.6 h to obtain a second slurry.

[0068] (5) The second slurry was cooled to 0°C in a circulating water bath, and a solution of 28.15g (0.32mol) NaH2PO2 and a solution of 9.7g (0.18mol) KBH4 were added dropwise under stirring. During this process, the pH was adjusted to 12 with a 30% aqueous ammonia solution. The molar ratio of the boron source to the phosphorus source was 1:1.8; the molar ratio of the nickel source to the total molar amount of the boron source and the phosphorus source was 1:3.92. After the addition was completed, the reaction was stopped by stirring until no gas was released, and the mixture was filtered. The black precipitate was collected by suction and washed repeatedly with deionized water until the pH was 7.2, and then washed twice with anhydrous ethanol. The obtained product was dried in a vacuum drying oven at 80°C for 7 h to obtain a nitro hydrogenation catalyst.

[0069] Example 4

[0070] A preparation method of a nitro hydrogenation catalyst:

[0071] The only difference between this embodiment and embodiment 1 is that in step (2), the molar ratio of the zirconium source to the cerium source is changed to 1:0.1.

[0072] Example 5

[0073] A preparation method of a nitro hydrogenation catalyst:

[0074] The only difference between this embodiment and embodiment 1 is that the molar ratio of the zirconium source to the cerium source is changed to 1:1 in step (2).

[0075] Example 6

[0076] A preparation method of a nitro hydrogenation catalyst:

[0077] The only difference between this embodiment and embodiment 1 is that in step (2), the ratio of the molar amount of citric acid to the total molar amount of the zirconium source and the cerium source is changed to 1:70.

[0078] Example 7

[0079] A preparation method of a nitro hydrogenation catalyst:

[0080] The only difference between this embodiment and embodiment 1 is that in step (2), the ratio of the molar amount of citric acid to the total molar amount of the zirconium source and the cerium source is changed to 1:100.

[0081] Example 8

[0082] A preparation method of a nitro hydrogenation catalyst:

[0083] The only difference between this embodiment and embodiment 1 is that in step (2), when the precipitant solution and mixed solution B are added dropwise to mixed solution A in parallel, heating is not performed, but the addition is performed directly at room temperature (25±5°C).

[0084] Example 9

[0085] A preparation method of a nitro hydrogenation catalyst:

[0086] The only difference between this embodiment and embodiment 1 is that in step (3), the reaction temperature of the hydrothermal reaction is changed to 110° C. and the holding time is changed to 15 h.

[0087] Example 10

[0088] A preparation method of a nitro hydrogenation catalyst:

[0089] The only difference between this embodiment and embodiment 1 is that in step (3), the reaction temperature of the hydrothermal reaction is changed to 160° C. and the holding time is changed to 6 h.

[0090] Example 11

[0091] A preparation method of a nitro hydrogenation catalyst:

[0092] The only difference between this embodiment and embodiment 1 is that in step (3), the calcination temperature of the calcination treatment is changed to 250°C.

[0093] Example 12

[0094] A preparation method of a nitro hydrogenation catalyst:

[0095] The only difference between this embodiment and embodiment 1 is that in step (3), the calcination temperature of the calcination treatment is changed to 450°C.

[0096] Example 13

[0097] A preparation method of a nitro hydrogenation catalyst:

[0098] The only difference between this embodiment and embodiment 1 is that in step (4), the weight ratio of the nickel source to the composite carrier is changed to 0.5:1.

[0099] Example 14

[0100] A preparation method of a nitro hydrogenation catalyst:

[0101] The only difference between this embodiment and embodiment 1 is that in step (4), the weight ratio of the nickel source to the composite carrier is changed to 1.2:1.

[0102] Example 15

[0103] A preparation method of a nitro hydrogenation catalyst:

[0104] The only difference between this embodiment and embodiment 1 is that in step (5), the molar ratio of the boron source to the phosphorus source is changed to 1:1; and the ratio of the molar amount of the nickel source to the total molar amount of the boron source and the phosphorus source is changed to 1:2.5.

[0105] Example 16

[0106] A preparation method of a nitro hydrogenation catalyst:

[0107] The only difference between this embodiment and embodiment 1 is that in step (5), the molar ratio of the boron source to the phosphorus source is changed to 1:1.2; and the ratio of the molar amount of the nickel source to the total molar amount of the boron source and the phosphorus source is changed to 1:4.5.

[0108] Comparative Example 1

[0109] A preparation method of a nitro hydrogenation catalyst:

[0110] The only difference between this comparative example and Example 1 is that steps (1), (4) and (5) are not performed. Instead, the cerium source is directly prepared into a solution and the precipitation, hydrothermal reaction and calcination steps are performed.

[0111] Comparative Example 2

[0112] A preparation method of a nitro hydrogenation catalyst:

[0113] The only difference between this comparative example and Example 1 is that steps (2), (4) and (5) are not performed, but the mixture A obtained in step (1) is directly subjected to a hydrothermal reaction and a calcination step.

[0114] Comparative Example 3

[0115] A preparation method of a nitro hydrogenation catalyst:

[0116] The only difference between this comparative example and Example 1 is that no boron source is added in step (4).

[0117] Comparative Example 4

[0118] A preparation method of a nitro hydrogenation catalyst:

[0119] The only difference between this comparative example and Example 1 is that no phosphorus source is added in step (5).

[0120] Application Example 1

[0121] Hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide:

[0122] The nitro hydrogenation catalyst obtained in Example 1 was used as the catalyst.

[0123] After 40 g of the catalyst was placed in a fixed bed, it was activated for 3 h at a heating rate of 10°C / min to 100°C under a hydrogen atmosphere.

[0124] The temperature was then lowered to 50°C, and a 0.5 M methanol solution of 2-nitro-N,3-dimethylbenzamide and hydrogen were introduced at a rate of 1 g / min and 20 mL / min, respectively, to allow for a catalytic hydrogenation reaction. Liquid phase analysis was performed after the reaction, and the results are shown in Table 1.

[0125] Application Example 2

[0126] Hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide:

[0127] The nitro hydrogenation catalyst obtained in Example 1 was used as the catalyst.

[0128] After 40 g of the catalyst was placed in a fixed bed, it was activated for 2 h at a heating rate of 10 °C / min to 140 °C under a hydrogen atmosphere.

[0129] The temperature was then lowered to 60°C, and a 0.5 M methanol solution of 2-nitro-N,3-dimethylbenzamide and hydrogen were introduced at a rate of 1 g / min and 25 mL / min, respectively, to allow for a catalytic hydrogenation reaction. Liquid phase analysis was performed after the reaction, and the results are shown in Table 1.

[0130] Application Example 3

[0131] Hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide:

[0132] The nitro hydrogenation catalyst obtained in Example 1 was used as the catalyst.

[0133] After 40 g of the catalyst was placed in a fixed bed, it was activated for 3 h at a heating rate of 10 °C / min to 150 °C under a hydrogen atmosphere.

[0134] Afterwards, the temperature was lowered to the reaction temperature of 55°C, and a 0.5M methanol solution of 2-nitro-N,3-dimethylbenzamide was introduced at a feed rate of 1 g / min and hydrogen was introduced at a feed rate of 30 mL / min to carry out a hydrogenation catalytic reaction. After the reaction, liquid phase testing was performed, and the results are shown in Table 1. The liquid phase test results are shown in the figure. Figure 1 .

[0135] Application Example 4

[0136] The nitro hydrogenation catalyst obtained in Example 4 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0137] Application Example 5

[0138] The nitro hydrogenation catalyst obtained in Example 5 was used as the catalyst and activated according to the conditions in Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0139] Application Example 6

[0140] The nitro hydrogenation catalyst obtained in Example 6 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0141] Application Example 7

[0142] The nitro hydrogenation catalyst obtained in Example 7 was used as the catalyst and activated according to the conditions in Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0143] Application Example 8

[0144] The nitro hydrogenation catalyst obtained in Example 8 was used as the catalyst and activated according to the conditions in Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0145] Application Example 9

[0146] The nitro hydrogenation catalyst obtained in Example 9 was used as the catalyst and activated according to the conditions in Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0147] Application Example 10

[0148] The nitro hydrogenation catalyst obtained in Example 10 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0149] Application Example 11

[0150] The nitro hydrogenation catalyst obtained in Example 11 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0151] Application Example 12

[0152] The nitro hydrogenation catalyst obtained in Example 12 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0153] Application Example 13

[0154] The nitro hydrogenation catalyst obtained in Example 13 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0155] Application Example 14

[0156] The nitro hydrogenation catalyst obtained in Example 14 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0157] Application Example 15

[0158] The nitro hydrogenation catalyst obtained in Example 15 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0159] Application Example 16

[0160] The nitro hydrogenation catalyst obtained in Example 16 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0161] Application Example 17

[0162] Hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide:

[0163] The nitro hydrogenation catalyst obtained in Example 1 was used as the catalyst.

[0164] After 40 g of the catalyst was placed in a fixed bed, it was activated for 4 h at a heating rate of 5 °C / min to 80 °C under a hydrogen atmosphere.

[0165] Afterwards, a hydrogenation catalytic reaction was carried out according to the conditions in Application Example 1. Liquid phase testing was performed after the reaction, and the results are shown in Table 1.

[0166] Application Example 18

[0167] Hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide:

[0168] The nitro hydrogenation catalyst obtained in Example 1 was used as the catalyst.

[0169] After 40 g of the catalyst was placed in a fixed bed, it was activated for 1 h at a heating rate of 15 °C / min to 160 °C under a hydrogen atmosphere.

[0170] Afterwards, a hydrogenation catalytic reaction was carried out according to the conditions in Application Example 1. Liquid phase testing was performed after the reaction, and the results are shown in Table 1.

[0171] Application Example 19

[0172] Hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide:

[0173] The nitro hydrogenation catalyst obtained in Example 1 was used as the catalyst, and activation treatment was performed according to the conditions in Application Example 1.

[0174] The temperature was then lowered to 45°C, and a 0.5 M methanol solution of 2-nitro-N,3-dimethylbenzamide and hydrogen were introduced at a rate of 0.5 g / min and 10 mL / min, respectively, to allow for a catalytic hydrogenation reaction. Liquid phase analysis was performed after the reaction, and the results are shown in Table 1.

[0175] Application Example 20

[0176] Hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide:

[0177] The nitro hydrogenation catalyst obtained in Example 1 was used as the catalyst, and activation treatment was performed according to the conditions in Application Example 1.

[0178] The temperature was then lowered to 65°C, and a 0.5 M methanol solution of 2-nitro-N,3-dimethylbenzamide and hydrogen were introduced at a rate of 1.5 g / min and 40 mL / min, respectively, to allow for a catalytic hydrogenation reaction. Liquid phase analysis was performed after the reaction, and the results are shown in Table 1.

[0179] Application Example 21

[0180] Hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide:

[0181] The nitro hydrogenation catalyst obtained in Example 1 was used as the catalyst and activated according to the conditions in Application Example 1. The test time was set to 2600 hours. Under long-term use conditions, the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide was carried out according to the conditions in Application Example 1. The reaction results using liquid phase testing are shown in Table 1.

[0182] Comparative Application Example 1

[0183] The nitro hydrogenation catalyst obtained in Comparative Example 1 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0184] Application Comparative Example 2

[0185] The nitro hydrogenation catalyst obtained in Comparative Example 2 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0186] Application Comparative Example 3

[0187] The nitro hydrogenation catalyst obtained in Comparative Example 3 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0188] Comparative Application Example 4

[0189] The nitro hydrogenation catalyst obtained in Comparative Example 4 was used as the catalyst and activated according to the conditions of Application Example 1 to achieve the hydrogenation reaction of 2-nitro-N,3-dimethylbenzamide. The reaction results were tested in liquid phase and are shown in Table 1.

[0190] Table 1

[0191]

[0192]

[0193] As can be seen from the above description, the embodiments of the present invention achieve the preparation of a nitro hydrogenation catalyst with superior performance compared to the comparative examples. The resulting catalyst, comprising a nano-amorphous Ni-B / P component, can continuously catalyze the hydrogenation of nitroaromatic compounds using a fixed bed under mild conditions, improving production conditions and achieving high conversion and selectivity for aniline.

[0194] Specifically, in each embodiment, by comparing Examples 4 and 5 with Examples 1 to 3, it can be seen that by optimizing the molar ratio of the zirconium source to the cerium source, it is more conducive to the preferential deposition of cerium ions on the surface of the ZrO2 particles, forming a more stable transition layer with a gradually increasing cerium content, thereby significantly enhancing the catalyst's adsorption capacity for nitro compounds.

[0195] Comparing Examples 6 and 7 with Examples 1 to 3, it can be seen that a more appropriate amount of acid agent can promote the composite support precursor to form a material with a highly stable and uniform structure during the hydrothermal treatment process, and ultimately optimize the activity of the resulting catalyst.

[0196] Comparing Example 8 with Examples 1 to 3, it can be seen that mixing solutions containing a zirconium source and a cerium source within a suitable temperature range and simultaneously performing precipitation reactions can further optimize the porosity and surface area of ​​the resulting support, providing more active sites for the subsequent deposition of amorphous alloys.

[0197] Comparing Examples 9 and 10 with Examples 1 to 3, it can be seen that the preferred temperature and time of the hydrothermal reaction can promote the uniform growth of zirconium-cerium oxide grains, thereby further improving the bonding strength between the amorphous alloy and the carrier, and ultimately resulting in higher catalytic activity.

[0198] Comparing Examples 11 and 12 with Examples 1 to 3, it can be seen that the preferred calcination temperature and conditions can further improve the thermal stability of the obtained composite support, promote the formation of oxygen vacancies on the support surface, and enhance the activity and stability of the obtained catalyst.

[0199] Comparing Examples 13 and 14 with Examples 1 to 3, it can be seen that the preferred weight ratio of the nickel source to the composite support can more significantly promote the strong interaction between the metal active component nickel and the support, ultimately improving the efficiency of the catalytic hydrogenolysis reaction, especially the breaking of the NO bond, thereby achieving more efficient nitro hydrogenation reaction.

[0200] Comparing Examples 15 and 16 with Examples 1 to 3, it can be seen that by optimizing the molar ratio of boron, phosphorus and nickel, the resulting catalyst can have a more stable electronic state and spatial configuration, achieving efficient cleavage of the NO bond in the nitro hydrogenation reaction, while reducing the occurrence of excessive hydrogenation side reactions, and improving the output purity and selectivity of aniline derivatives.

[0201] In the application of the nitro hydrogenation catalysts obtained in each example as hydrogenation catalysts, by comparing Application Examples 17 and 18 with Application Example 1, it can be seen that the preferred activation treatment conditions of the nitro hydrogenation catalysts can more effectively pre-react with hydrogen at the oxygen vacancies on the surface of the nitro hydrogenation catalysts to form more active hydrogen species, thereby more effectively participating in the subsequent hydrogenation reaction and promoting the conversion of nitro compounds. By comparing Application Examples 19 and 20 with Application Example 1, it can be seen that for the catalysts obtained in the examples of the present invention, the preferred application conditions can promote the catalyst's activity and stability to be more fully exerted, thereby achieving a more efficient and highly selective hydrogenation reaction of nitroaromatics.

[0202] It should be noted that the terms "first," "second," and the like in the specification and claims of this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the application described herein can, for example, be implemented in an order other than that described herein.

[0203] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a nitro hydrogenation catalyst, characterized in that: include: Step S1, preparing a zirconium source solution by combining a zirconium source, a first acid agent, and water, and adding a first precipitant to the zirconium source solution to obtain a mixed solution A having a pH of 8.5 to 9.0; Step S2, preparing a mixed solution B with a cerium source, a second acid agent, and water, and adding the mixed solution B and a second precipitant to the mixed solution A to obtain a mixed solution C with a pH of 6.8 to 7.2; Step S3, the mixed solution C is subjected to a hydrothermal reaction to obtain a carrier precursor; The carrier precursor is calcined to obtain a composite carrier; Step S4, preparing the composite support and water into a first slurry, and adding a nickel source to the first slurry to obtain a second slurry after mixing; Step S5, adding a boron source and a phosphorus source to the second slurry at 0±5° C. and stirring to react, so that the boron source, the phosphorus source, and the nickel source are deposited on the composite support to form an amorphous alloy, thereby obtaining the nitro hydrogenation catalyst; The molar ratio of the zirconium source to the cerium source is 1:(0.2-0.5); The first acid agent and the second acid agent are each independently selected from one or more of citric acid and oxalic acid, and the first acid agent and the second acid agent are both added in the form of an acid solution with a molar concentration of 0.08M to 0.1M.

2. The method for preparing a nitro hydrogenation catalyst according to claim 1, wherein The zirconium source is selected from one or more of zirconium nitrate, zirconium oxychloride, zirconium acetate, zirconium sulfate, zirconium carbonate and zirconium chloride; and / or, The cerium source is selected from one or more of cerium nitrate, cerium chloride and cerium acetate.

3. The preparation method of the nitro hydrogenation catalyst according to claim 1, characterized in that The total molar amount of the zirconium source and the cerium source is denoted as M1, the total molar amount of the first acid agent and the second acid agent is denoted as M2, M2:M1=1:(75-95); and / or, The first precipitant and the second precipitant are each independently selected from one or more of sodium hydroxide, sodium carbonate and aqueous ammonia.

4. The method for preparing a nitro hydrogenation catalyst according to any one of claims 1 to 3, characterized in that: In the step S3, The hydrothermal reaction temperature is 120° C. to 150° C., and the reaction time is 8 h to 12 h; and / or, The calcination temperature of the calcination treatment is 300° C. to 400° C., and the calcination treatment is performed in an inert atmosphere.

5. The method for preparing a nitro hydrogenation catalyst according to any one of claims 1 to 3, characterized in that: In the step S4, The weight ratio of the nickel source to the composite support is (0.6-1.12):1; and / or, The mixing is stirring and mixing, and the stirring and mixing time is 0.5h~1h; and / or, The nickel source is selected from one or more of nickel nitrate, nickel sulfate hexahydrate and nickel chloride.

6. The method for preparing a nitro hydrogenation catalyst according to any one of claims 1 to 3, characterized in that: In the step S5, The molar ratio of the boron source to the phosphorus source is 1:(1.5-2); and / or, The ratio of the molar amount of the nickel source to the total molar amount of the boron source and the phosphorus source is 1:(2.8-4.0); The boron source is selected from one or more of KBH4, NaBH4 and (CH3COO)3BHNa; and / or, The phosphorus source is selected from one or more of NaH2PO2, H3PO2 and H6NO3P; and / or, The boron source and the phosphorus source are added dropwise, and during the dropwise addition, step S5 further includes adding an alkaline solution to the second slurry to maintain the pH of the second slurry at 12±0.2; The alkaline solution is selected from one or more of sodium hydroxide solution, sodium carbonate solution and ammonia water.

7. A nitro hydrogenation catalyst, characterized in that The nitro hydrogenation catalyst is prepared by the preparation method of the nitro hydrogenation catalyst according to any one of claims 1 to 6.

8. A method for preparing aniline compounds by catalytic hydrogenation, characterized in that: The nitroaromatic compound and hydrogen are subjected to a hydrogenation reaction under the action of the nitro hydrogenation catalyst according to claim 7 to obtain the aniline compound.

9. The method for preparing aniline compounds by catalytic hydrogenation according to claim 8, characterized in that: Before the hydrogenation reaction, the catalytic hydrogenation preparation method of aniline compounds further includes loading the nitro hydrogenation catalyst into a fixed bed and performing an activation treatment, wherein the activation treatment includes: Under a hydrogen atmosphere, heat to 100°C~150°C at a heating rate of 10±2°C / min and keep warm for 2h~3h.

10. The method for preparing aniline compounds by catalytic hydrogenation according to claim 8 or 9, characterized in that: In the hydrogenation reaction, The feeding rate of the nitroaromatic compound is 1.0±0.2 g / min; The feed rate of the hydrogen is 20 mL / min to 30 mL / min; The reaction temperature is 50℃~60℃.

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