High-activity nickel-based catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, in particular to a high-activity nickel-based catalyst and a preparation method and application thereof. The catalyst containing a high-dispersion Ni active component and a SiO2-CeO2 / ZrO2 composite carrier is prepared by adopting two microfiltration membrane reactors connected in series and a fractional precipitation process and taking sodium silicate nonahydrate as a silicon source and nickel nitrate and cerous / zirconium nitrate as metal sources, a surfactant is not needed in preparation, and the process is continuous and controllable. The catalyst is used for preparing 4, 4 '-diaminodiphenyl ether through fixed bed continuous catalysis and hydrogenation of 4, 4'-dinitrodiphenyl ether, a liquid-phase material and hydrogen are preheated and mixed and then react, the reaction temperature and pressure are mild, and the continuous production requirement is met. The preparation and production energy consumption cost of the catalyst is greatly reduced, the catalyst is high in activity and stability, the process is environment-friendly and easy to industrialize, and the problems that a traditional catalyst is poor in dispersion, high in cost and intermittent in process are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a highly active nickel-based catalyst, its preparation method, and its application. Background Technology

[0002] 4,4'-Diaminodiphenyl ether (ODA), as a multifunctional fine chemical intermediate, holds an irreplaceable position in modern chemical engineering. Its core application is concentrated in the synthesis of polyimide materials. Polyimide, with its excellent dielectric properties, chemical stability, and resistance to extreme temperatures, has become a key raw material in high-end fields such as films, fibers, electrical insulation, liquid crystal displays, and aerospace composites. In addition, ODA is widely used in the synthesis of azo dyes, the preparation of epoxy resin curing agents and crosslinking agents, and other applications, with market demand continuing to grow steadily. With the development of downstream high-end manufacturing industries, higher demands are being placed on the production efficiency, product purity, and production cost control of ODA, driving technological innovation in its synthesis processes and core catalysts.

[0003] Currently, the mainstream industrial route for ODA preparation is the reduction reaction of 4,4'-dinitrodiphenyl ether (DNDPE). Among these methods, catalytic hydrogenation has gradually replaced traditional chemical reduction methods such as iron powder reduction and sodium sulfide reduction due to its advantages of simple synthesis process, high atom economy, high product purity, and low emissions of waste. Catalysts used in catalytic hydrogenation are mainly divided into two categories: noble metal catalysts and non-noble metal catalysts. Although noble metal catalysts exhibit excellent catalytic activity, the high price of precious metals such as Pd and Pt leads to high production costs, limiting their large-scale industrial application. Among non-noble metal catalysts, skeletal nickel is a widely used variety, but this catalyst poses safety hazards such as difficulty in storage and flammability / explosion, and its catalytic selectivity and stability need improvement. In recent years, researchers have been working on optimizing non-precious metal catalysts. For example, the Salen-Ni(II) complex supported catalyst disclosed in patent CN118771992A has excellent hydrogenation performance, but the preparation process of the metal complex is cumbersome. Patent CN119390589A uses tetraethyl silicate as a silicon source to prepare a nickel-based catalyst, but it still has the problem of high preparation cost due to the use of a large amount of ethanol as a solvent. Moreover, both types of catalysts rely on high-pressure batch hydrogenation process, which is not conducive to automated production and poses significant safety hazards.

[0004] In practical applications of catalytic hydrogenation, the structural characteristics and preparation process of the catalyst directly determine the reaction efficiency and product quality. Existing non-precious metal nickel-based catalysts generally suffer from problems such as uneven dispersion of active components, difficulty in controlling the support structure, and complex preparation processes, leading to insufficient catalytic selectivity and short lifespan. Meanwhile, inappropriate selection of raw materials such as silicon sources and solvents further increases production costs, while batch reaction processes restrict the improvement of production efficiency and fail to meet the demands of continuous industrial production. Therefore, developing a non-precious metal catalyst system with a simple preparation process, low production cost, high hydrogenation activity, and strong stability, coupled with an efficient continuous hydrogenation reaction process, has become a key direction for solving the current pain points of ODA synthesis technology and promoting technological upgrading in the industry, possessing significant industrial application value and market prospects. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art by proposing a highly active nickel-based catalyst, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention provides a method for preparing a highly active nickel-based catalyst, comprising the following steps:

[0007] (1) Adding Na2SiO3·9H2O to distilled water yields solution A; adding sulfuric acid to distilled water yields solution B; adding metal nitrate to distilled water yields solution C; adding Na2CO3 to distilled water yields solution D.

[0008] (2) After solution A is introduced into the first microporous membrane reactor at a certain flow rate, it is mixed with solution B. The pH value of the mixed solution is adjusted to 8-9 by adjusting the flow rate of solution B. Then it is introduced into a polytetrafluoroethylene tube with an inner diameter of 3 mm. After the temperature is raised to 70℃, it reacts to form silica gel. After mixing with solution C at a certain flow rate through a T-shaped tee, it is introduced into a polytetrafluoroethylene tube with an inner diameter of 3 mm as a continuous phase and enters the second microporous membrane reactor. Solution D is mixed with it as a dispersed phase at a certain flow rate and then introduced into a polytetrafluoroethylene tube with an inner diameter of 3 mm. After reacting in a water bath at 60℃, the precipitate is collected.

[0009] (3) The precipitate was centrifuged, washed with distilled water until neutral, dried, and ground into powder to obtain dry precipitate powder. Then, boehmite and distilled water were added and mixed thoroughly and ground into a paste. The paste was extruded into strips with a diameter of about 2 mm, dried at room temperature, and then dried in an oven. After drying, the temperature was increased to 300-500℃ at 5℃ / min and calcined for 4 h to obtain catalyst precursor.

[0010] (4) The catalyst precursor is loaded into a fixed bed reactor, heated to 450-550℃, and reduced for 3h under H2 gas flow to obtain a high-efficiency nickel-based catalyst.

[0011] Preferably, the concentration of Na2SiO3·9H2O in solution A in (1) is 0.01-0.5 mol / L.

[0012] More preferably, the concentration of Na2SiO3·9H2O in solution A in (1) is 0.09-0.3 mol / L.

[0013] Most preferably, the concentration of Na2SiO3·9H2O in solution A in (1) is 0.25 mol / L.

[0014] Preferably, the concentration of sulfuric acid in solution B in (1) is 0.01-0.5 mol / L.

[0015] More preferably, the concentration of sulfuric acid in solution B in (1) is 0.3 mol / L.

[0016] Preferably, the concentration of metal nitrate in solution C in (1) is 0.01-0.5 mol / L.

[0017] More preferably, the concentration of metal nitrate in solution C in (1) is 0.2-0.45 mol / L.

[0018] Most preferably, the concentration of metal nitrate in solution C in (1) is 0.25 mol / L.

[0019] Preferably, the concentration of Na2CO3 in solution D in (1) is 0.01-0.5 mol / L.

[0020] More preferably, the concentration of Na2CO3 in solution D in (1) is 0.3 mol / L.

[0021] Preferably, the metal nitrate in (1) refers to a mixture of nickel nitrate and cerium nitrate or zirconium nitrate in a molar ratio of 0.85-0.95:0.05-0.15.

[0022] More preferably, the metal nitrate in (1) refers to a mixture of nickel nitrate and cerium nitrate in a molar ratio of 0.85-0.9:0.1-0.15.

[0023] Most preferably, the metal nitrate in (1) refers to a mixture of nickel nitrate and cerium nitrate in a molar ratio of 0.85:0.15.

[0024] Preferably, the flow rates of solutions A, B, and C in (2) are 1-30 ml / min.

[0025] More preferably, the flow rates of solutions A, B, and C in (2) are 5 ml / min.

[0026] Preferably, the pore size of the microporous membrane reactor in (2) is 0.1-50 μm.

[0027] Preferably, the amount of boehmite added in (3) is 5-15% of the weight of the dried precipitate powder.

[0028] More preferably, the amount of boehmite added in (3) is 10% of the weight of the dried precipitate powder.

[0029] Preferably, the amount of distilled water added in (3) is 30-60% of the weight of the dried precipitate powder.

[0030] More preferably, the amount of distilled water added in (3) is 40% of the weight of the dried precipitate powder.

[0031] More preferably, the calcination temperature in (3) is 350-400℃.

[0032] Most preferably, the calcination temperature in (3) is 400°C.

[0033] Preferably, the flow rate of H2 gas in (4) is 100 ml / min.

[0034] More preferably, the reduction temperature in (4) is 500°C.

[0035] Furthermore, the present invention also provides a highly active nickel-based catalyst prepared using the above-described preparation method.

[0036] Preferably, the highly active nickel-based catalyst is represented as... Where A represents the molar concentration of metallic nitrate in solution C during the preparation process, x, y, and z represent the molar ratios of Ni in nickel nitrate in solution C to SiO2 converted from Na2SiO3·9H2O in solution A through sulfuric acid acidification and calcination, and M in solution C, respectively; M represents Ce or Zr in metallic nitrate, h represents the calcination temperature, and r represents the reduction temperature.

[0037] Preferably, the mechanism of action of the highly active nickel-based catalyst of the present invention is as follows:

[0038] This invention employs an innovative preparation process of "tandem dual-membrane dispersion microreactors + stepwise precipitation," laying the structural foundation for high catalyst activity from the outset. Its core advantage lies in the precise control of the distribution of the support and active components. First, using inexpensive sodium silicate nonahydrate as the silicon source (replacing tetraethyl silicate in existing technologies to reduce costs), a sodium silicate solution (solution A) is mixed with a sulfuric acid solution (solution B) through a first membrane dispersion microreactor. The microporous membrane within the reactor shears the dispersed phase into micron-sized droplets, enabling rapid and uniform contact between sodium silicate and sulfuric acid. This avoids the agglomeration of silicate gel caused by excessively high local acid concentrations in traditional precipitation methods, ultimately generating a porous and uniformly structured silicate gel. This uniform gel structure not only has sufficient specific surface area but also provides numerous well-organized loading sites, creating conditions for the subsequent uniform deposition of metal ions.

[0039] Subsequently, the silica gel was mixed with a Ni, Ce / Zr metal nitrate solution (solution C) and then introduced into a second membrane dispersion microreactor, where it combined with a Na₂CO₃ solution (solution D) as the dispersed phase through a co-precipitation reaction. Again relying on the efficient mass transfer characteristics of membrane dispersion, metal ions (Ni... 2+ Ce 3+ / Zr 4+ This process enables simultaneous and uniform nucleation and growth on the surface of silica gel, achieving high dispersion of Ni active components without the addition of any surfactants. This design simplifies the preparation steps (eliminating the need for subsequent washing with surfactants) and avoids the problems of surfactant residues clogging active sites or reducing Ni catalytic activity. Simultaneously, Ce / Zr ions are uniformly doped into the support, not simply mixed, but forming a stable composite support structure with SiO2, providing a prerequisite for the synergistic effect of subsequent catalytic reactions. This stepwise precipitation and membrane dispersion process fundamentally solves the pain points of "uneven dispersion of active components and agglomeration of support structure" in traditional preparations, constructing a core structure of "porous support + highly dispersed active components," providing sufficient active sites for catalytic hydrogenation reactions.

[0040] The high hydrogenation activity of the catalyst stems from the synergistic effect of the Ni active center and the SiO2-CeO2 / ZrO2 composite support, specifically in its efficient promotion of key reaction steps. First, the highly dispersed Ni is the core active center for catalytic hydrogenation: due to the membrane dispersion process ensuring uniform Ni distribution during preparation, each Ni nanoparticle can independently serve as an active site, efficiently adsorbing and dissociating H2 molecules to generate active hydrogen species (H*). This step is the rate-controlling step of the hydrogenation reaction; the high dispersion of Ni means more H2 dissociation sites, directly improving the efficiency of active hydrogen generation. Simultaneously, the dispersed Ni particles can also stably adsorb the substrate near the active site through coordination with the nitro groups in the DNDPE molecule, allowing the active hydrogen species to rapidly combine with the nitro groups, gradually reducing -NO2 to -NH2, ultimately generating the target product ODA. Second, the SiO2-CeO2 / ZrO2 composite support further enhances the catalytic performance. SiO2 itself possesses excellent thermal stability and a porous structure, which can immobilize Ni particles through steric hindrance, preventing their aggregation during the reaction (avoiding the loss of active sites). Simultaneously, the porous structure can promote mass transfer between substrate and product, reducing reaction resistance. The introduction of CeO2 or ZrO2, on the other hand, modulates the catalytic performance of Ni through electronic effects—Ce(CeO2)… 3+ / Ce 4+ ) or Zr(Zr 3+ / Zr 4+ The variable valence state of the catalyst can transfer electrons with Ni, reducing the activation energy of Ni's dissociation of H2 (making it easier for H2 to generate H*), while enhancing Ni's adsorption capacity for DNDPE nitro groups and reducing the occurrence of side reactions. In addition, the pseudoboehmite binder not only ensures the extrusion molding of the catalyst (meeting the mechanical strength requirements of fixed-bed reactions and avoiding bed blockage), but also forms chemical bonds with the support and Ni particles through surface hydroxyl groups, further stabilizing the dispersion state of Ni and extending the catalyst lifetime.

[0041] The preparation method of this invention not only constructs a highly active catalyst structure, but also achieves a unity of "high activity" and "industrial applicability" through multiple process advantages, forming a positive cycle of "process-structure-performance". First, it offers significant cost advantages: using sodium silicate nonahydrate (inorganic silicon source) instead of the commonly used tetraethyl silicate (organosilicon source) in existing technologies reduces raw material costs; the absence of surfactants reduces auxiliary material costs and eliminates complex subsequent washing steps, lowering process energy consumption. Second, it offers strong continuity and controllability: the series design of the dual-membrane dispersion microreactor enables continuous operation of "silicic acid gel preparation - metal coprecipitation," increasing production efficiency by 2-3 times compared to traditional batch sedimentation. Furthermore, by adjusting parameters such as flow rate, temperature, and pH, the structure of the carrier and active components can be precisely controlled, ensuring batch stability and solving the industrial pain point of "large batch variations" in traditional batch preparation. Third, it is suitable for continuous fixed-bed reactions: the subsequent extrusion molding, segmented drying and calcination, and reduction processes give the catalyst good mechanical strength and thermal stability, making it suitable for continuous hydrogenation reactions in fixed beds. It can operate efficiently under low temperature and low pressure conditions (50-150℃, 0.3-3.0MPa), which reduces the material requirements of the reaction equipment and reduces the occurrence of side reactions under high temperature and high pressure, meeting the industrial demand for "continuous production, low energy consumption, and high stability".

[0042] Furthermore, the present invention also provides the application of a highly active nickel-based catalyst in the continuous catalytic hydrogenation preparation of 4,4'-diaminodiphenyl ether, comprising the following steps:

[0043] A fixed-bed reactor was used, with a nickel-based highly active catalyst packed in a constant-temperature layer in the middle of the reactor. The temperature inside the catalyst bed was monitored by thermocouples. The liquid phase material, a mixture of 4,4'-dinitrodiphenyl ether and N,N-dimethylacetamide, was pumped to the preheater through a stainless steel pipe with an inner diameter of 0.3 mm by a horizontal flow pump. Hydrogen gas was introduced into the preheater through a pressure reducing valve and a gas mass flow meter to mix with the liquid phase material. After being preheated to 50-150°C in the preheater, it entered the reactor. The reaction temperature was 50-150°C. A condenser and a storage tank were connected to the bottom of the reactor, and the system pressure was controlled by a back pressure valve. The reaction product was separated into gas and liquid phases. The liquid phase material was collected, and N,N-dimethylacetamide was recovered by vacuum distillation. The remaining product was recrystallized in ethanol to obtain 4,4'-diaminodiphenyl ether.

[0044] Preferably, the chemical reaction equation for the continuous catalytic hydrogenation to prepare 4,4'-diaminodiphenyl ether is as follows:

[0045]

[0046] Preferably, the reaction temperature is 100°C.

[0047] Preferably, the 4,4'-dinitrodiphenyl ether and N,N-dimethylacetamide are in a weight ratio of 1:3-10.

[0048] More preferably, the 4,4'-dinitrodiphenyl ether and N,N-dimethylacetamide are in a weight ratio of 1:4.

[0049] Preferably, the molar ratio of 4,4'-dinitrodiphenyl ether to hydrogen is 1:5-50.

[0050] More preferably, the molar ratio of the 4,4'-dinitrodiphenyl ether to hydrogen is 1:25.

[0051] Preferably, the rate at which the liquid phase material enters the reactor is 0.05-1.0 h⁻¹ of the catalyst volume. -1 The system pressure is 0.3-3.0 MPa.

[0052] More preferably, the rate at which the liquid phase material enters the reactor is 0.1 h of the catalyst volume. -1 The system pressure is 1 MPa.

[0053] The beneficial effects of this invention are:

[0054] 1. This invention solves the problems of uneven dispersion of active components and agglomeration of support structures in traditional catalyst preparation by using an innovative preparation process of two microporous membrane reactors connected in series and stepwise precipitation. The cross-flow shearing effect of the microporous membrane on the dispersed phase can transform the solution into micron-sized droplets, achieving instantaneous and uniform mixing of sodium silicate and sulfuric acid, and metal ions and sodium carbonate. This allows for high dispersion of the Ni active component on the support surface without the need for surfactants, constructing a SiO2-CeO2 / ZrO2 composite support. This provides sufficient active sites for the catalytic hydrogenation reaction, ensuring catalytic efficiency from a structural perspective. Furthermore, the preparation process is continuous and controllable, simplifying the complex steps in traditional processes.

[0055] 2. This invention offers significant cost advantages in raw material selection and process design. It utilizes inexpensive sodium silicate nonahydrate as the silicon source, replacing organosilicon sources such as tetraethyl silicate in existing technologies, thus substantially reducing the cost of the carrier raw materials. Using non-precious metal Ni as the active component avoids the high cost problem of precious metal catalysts. Simultaneously, the preparation process eliminates the need for surfactants, reducing auxiliary material costs and subsequent washing steps, thereby lowering process energy consumption. Furthermore, compared to traditional batch sedimentation, the continuous preparation process significantly improves production efficiency, further reducing the unit product cost and meeting the economic requirements of large-scale industrial production.

[0056] 3. The nickel-based catalyst of this invention exhibits excellent catalytic performance and long-term stability. The highly dispersed Ni active centers can efficiently adsorb and dissociate H2 to generate active hydrogen species. Combined with the synergistic effect of the SiO2-CeO2 / ZrO2 composite support, SiO2 prevents Ni agglomeration through steric hindrance, while the variable valence states of Ce / Zr regulate the Ni electronic environment and enhance nitro adsorption selectivity, effectively reducing side reactions. The boehmite binder not only ensures the mechanical strength of the catalyst but also stabilizes the Ni dispersion state through chemical bonds, enabling the catalyst to maintain high catalytic efficiency under a wide range of process conditions and exhibit minimal activity decay during long-term operation, thus extending its service life.

[0057] 4. The catalytic system of this invention is highly compatible with continuous hydrogenation processes, possessing outstanding industrial applicability. The catalyst can be directly loaded into a fixed-bed reactor, adapting to continuous production processes without frequent equipment start-ups and shutdowns, thus improving production efficiency. The required reaction temperature and pressure are mild, with lower requirements for equipment materials, reducing equipment investment costs. The solvent in the liquid phase material after the reaction can be recovered and recycled through vacuum distillation, reducing solvent loss and "three wastes" emissions, which aligns with the direction of green chemical development. At the same time, it simplifies the product separation and purification process, helping to achieve efficient, environmentally friendly, and continuous ODA production. Attached Figure Description

[0058] Figure 1 This is a flowchart illustrating the preparation process of the high-efficiency nickel-based catalyst in this invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0060] The following embodiments are all in accordance with Figure 1 The process flow diagram for preparing medium- and high-efficiency nickel-based catalysts was obtained.

[0061] Example 1: A specific preparation method of a highly active nickel-based catalyst, comprising the following steps:

[0062] (1) Add Na2SiO3·9H2O to distilled water to prepare a solution A with a concentration of 0.25 mol / L; add sulfuric acid to distilled water to prepare a solution B with a concentration of 0.3 mol / L; add metallic nitrate (molar ratio of nickel nitrate to cerium nitrate is 0.85:0.15) to distilled water to prepare a solution C with a concentration of 0.25 mol / L; add Na2CO3 to distilled water to prepare a solution D with a concentration of 0.3 mol / L.

[0063] (2) After solution A is introduced into the first microporous membrane reactor at a flow rate of 5 ml / min, it is mixed with solution B. The pH value of the mixed solution is adjusted to 8-9 by adjusting the flow rate of solution B. Then it is introduced into a 150 ml polytetrafluoroethylene tube with an inner diameter of 3 mm. After the temperature is raised to 70℃ to react and form silica gel, it is mixed with solution C at a flow rate of 5 ml / min through a T-shaped tee. Then it is introduced into a 50 ml polytetrafluoroethylene tube with an inner diameter of 3 mm as a continuous phase and enters the second microporous membrane reactor. Solution D is introduced into the reactor as a dispersed phase at a flow rate of 5 ml / min and mixed with it. Then it is introduced into a 40 ml polytetrafluoroethylene tube with an inner diameter of 3 mm. After the reaction is carried out in a 60℃ water bath, the precipitate is collected.

[0064] (3) The precipitate was centrifuged, washed with distilled water until neutral, dried, and ground into powder to obtain dry precipitate powder. Then, 10% of the mass of the dry precipitate powder of boehmite and 40% of the mass of the dry precipitate powder of distilled water were added and mixed thoroughly until a paste was formed. The paste was extruded into strips with a diameter of about 2 mm, dried at room temperature, and then dried in an oven. After drying, the temperature was increased to 400℃ at 5℃ / min and calcined for 4 hours to obtain the catalyst precursor.

[0065] (4) The catalyst precursor was loaded into a fixed-bed reactor, heated to 500℃, and reduced for 3 hours under an H2 gas flow (flow rate 100 ml / min) to obtain a highly efficient nickel-based catalyst, denoted as […].

[0066] Example 2: A specific preparation method of a highly active nickel-based catalyst, comprising the following steps:

[0067] (1) Add Na2SiO3·9H2O to distilled water to prepare a solution A with a concentration of 0.25 mol / L; add sulfuric acid to distilled water to prepare a solution B with a concentration of 0.3 mol / L; add metallic nitrate (molar ratio of nickel nitrate to cerium nitrate is 0.9:0.1) to distilled water to prepare a solution C with a concentration of 0.25 mol / L; add Na2CO3 to distilled water to prepare a solution D with a concentration of 0.3 mol / L.

[0068] (2) After solution A is introduced into the first microporous membrane reactor at a flow rate of 5 ml / min, it is mixed with solution B. The pH value of the mixed solution is adjusted to 8-9 by adjusting the flow rate of solution B. Then it is introduced into a 150 ml polytetrafluoroethylene tube with an inner diameter of 3 mm. After the temperature is raised to 70℃ to react and form silica gel, it is mixed with solution C at a flow rate of 5 ml / min through a T-shaped tee. Then it is introduced into a 50 ml polytetrafluoroethylene tube with an inner diameter of 3 mm as a continuous phase and enters the second microporous membrane reactor. Solution D is introduced into the reactor as a dispersed phase at a flow rate of 5 ml / min and mixed with it. Then it is introduced into a 40 ml polytetrafluoroethylene tube with an inner diameter of 3 mm. After the reaction is carried out in a 60℃ water bath, the precipitate is collected.

[0069] (3) The precipitate was centrifuged, washed with distilled water until neutral, dried, and ground into powder to obtain dry precipitate powder. Then, 10% of the mass of the dry precipitate powder of boehmite and 40% of the mass of the dry precipitate powder of distilled water were added and mixed thoroughly until a paste was formed. The paste was extruded into strips with a diameter of about 2 mm, dried at room temperature, and then dried in an oven. After drying, the temperature was increased to 400℃ at 5℃ / min and calcined for 4 hours to obtain the catalyst precursor.

[0070] (4) The catalyst precursor was loaded into a fixed-bed reactor, heated to 500℃, and reduced for 3 hours under an H2 gas flow (flow rate 100 ml / min) to obtain a highly efficient nickel-based catalyst, denoted as […].

[0071] Example 3: A specific preparation method of a highly active nickel-based catalyst, comprising the following steps:

[0072] (1) Add Na2SiO3·9H2O to distilled water to prepare a solution A with a concentration of 0.25 mol / L; add sulfuric acid to distilled water to prepare a solution B with a concentration of 0.3 mol / L; add metallic nitrate (molar ratio of nickel nitrate to cerium nitrate is 0.85:0.15) to distilled water to prepare a solution C with a concentration of 0.25 mol / L; add Na2CO3 to distilled water to prepare a solution D with a concentration of 0.3 mol / L.

[0073] (2) After solution A is introduced into the first microporous membrane reactor at a flow rate of 5 ml / min, it is mixed with solution B. The pH value of the mixed solution is adjusted to 8-9 by adjusting the flow rate of solution B. Then it is introduced into a 150 ml polytetrafluoroethylene tube with an inner diameter of 3 mm. After the temperature is raised to 70℃ to react and form silica gel, it is mixed with solution C at a flow rate of 5 ml / min through a T-shaped tee. Then it is introduced into a 50 ml polytetrafluoroethylene tube with an inner diameter of 3 mm as a continuous phase and enters the second microporous membrane reactor. Solution D is introduced into the reactor as a dispersed phase at a flow rate of 5 ml / min and mixed with it. Then it is introduced into a 40 ml polytetrafluoroethylene tube with an inner diameter of 3 mm. After the reaction is carried out in a 60℃ water bath, the precipitate is collected.

[0074] (3) The precipitate was centrifuged, washed with distilled water until neutral, dried, and ground into powder to obtain dry precipitate powder. Then, 10% of the mass of the dry precipitate powder of boehmite and 40% of the mass of the dry precipitate powder of distilled water were added and mixed thoroughly until a paste was formed. The paste was extruded into strips with a diameter of about 2 mm, dried at room temperature, and then dried in an oven. After drying, the temperature was increased to 350℃ at 5℃ / min and calcined for 4 h to obtain the catalyst precursor.

[0075] (4) The catalyst precursor was loaded into a fixed-bed reactor, heated to 500℃, and reduced for 3 hours under an H2 gas flow (flow rate 100 ml / min) to obtain a highly efficient nickel-based catalyst, denoted as […].

[0076] Example 4: The difference between Example 4 and Example 1 is as follows: Na₂SiO₃·9H₂O is added to distilled water to prepare a solution A with a concentration of 0.2 mol / L; a metal nitrate (molar ratio of nickel nitrate to cerium nitrate is 0.9:0.1) is added to distilled water to prepare a solution C with a concentration of 0.25 mol / L; other step parameters are the same as in Example 1, and the resulting catalyst can be represented as...

[0077] Example 5: The difference between Example 5 and Example 1 is that the calcination temperature is reduced to 350°C; other step parameters are the same as in Example 1, and the resulting catalyst can be represented as follows:

[0078] Example 6: The difference between Example 6 and Example 1 is as follows: Na₂SiO₃·9H₂O is added to distilled water to prepare a solution A with a concentration of 0.09 mol / L; a metal nitrate (molar ratio of nickel nitrate to cerium nitrate is 0.9:0.1) is added to distilled water to prepare a solution C with a concentration of 0.15 mol / L; other step parameters are the same as in Example 1, and the resulting catalyst can be represented as...

[0079] Example 7: The difference between Example 7 and Example 1 is as follows: Na₂SiO₃·9H₂O is added to distilled water to prepare a solution A with a concentration of 0.15 mol / L; a metal nitrate (molar ratio of nickel nitrate to cerium nitrate is 0.9:0.1) is added to distilled water to prepare a solution C with a concentration of 0.25 mol / L; other step parameters are the same as in Example 1, and the resulting catalyst can be represented as...

[0080] Example 8: The difference between Example 8 and Example 1 is as follows: Na₂SiO₃·9H₂O is added to distilled water to prepare a solution A with a concentration of 0.12 mol / L; a metal nitrate (molar ratio of nickel nitrate to cerium nitrate is 0.9:0.1) is added to distilled water to prepare a solution C with a concentration of 0.2 mol / L; other step parameters are the same as in Example 1, and the resulting catalyst can be represented as...

[0081] Example 9: The difference between Example 9 and Example 1 is that the reduction temperature is lowered to 450°C, while other step parameters are the same as in Example 1. The resulting catalyst can be represented as follows:

[0082] Example 10: The difference between Example 10 and Example 1 is that: a metal nitrate (molar ratio of nickel nitrate to cerium nitrate is 0.8:0.2) is added to distilled water to prepare a solution C with a concentration of 0.25 mol / L; other step parameters are the same as in Example 1, and the resulting catalyst can be represented as:

[0083] Example 11: The difference between Example 11 and Example 1 is that: a metal nitrate (molar ratio of nickel nitrate to cerium nitrate is 0.95:0.05) is added to distilled water to prepare a solution C with a concentration of 0.25 mol / L; other step parameters are the same as in Example 1, and the resulting catalyst can be represented as:

[0084] Example 12: The difference between Example 12 and Example 1 is that: Na2SiO3·9H2O was added to distilled water to prepare a solution A with a concentration of 0.09 mol / L; a metal nitrate (nickel nitrate and zirconium nitrate in a molar ratio of 0.9:0.1) was added to distilled water to prepare a solution C with a concentration of 0.15 mol / L; other steps and parameters were the same as in Example 1, and the resulting catalyst can be represented as...

[0085] Example 13: The difference between Example 13 and Example 1 is that: Na2SiO3·9H2O was added to distilled water to prepare a solution A with a concentration of 0.30 mol / L; a metal nitrate (nickel nitrate and zirconium nitrate in a molar ratio of 0.9:0.1) was added to distilled water to prepare a solution C with a concentration of 0.25 mol / L; other steps and parameters were the same as in Example 1, and the resulting catalyst can be represented as...

[0086] Example 14: The difference between Example 14 and Example 1 is that the reduction temperature is increased to 550°C, while other step parameters are the same as in Example 1. The resulting catalyst can be represented as follows:

[0087] Example 15: The difference between Example 15 and Example 1 is that: Na₂SiO₃·9H₂O was added to distilled water to prepare a solution A with a concentration of 0.18 mol / L; a metal nitrate (nickel nitrate and zirconium nitrate in a molar ratio of 0.9:0.1) was added to distilled water to prepare a solution C with a concentration of 0.3 mol / L; other steps and parameters were the same as in Example 1, and the resulting catalyst can be represented as...

[0088] Example 16: The difference between Example 16 and Example 1 is that the calcination temperature is increased to 500°C, while other step parameters are the same as in Example 1. The resulting catalyst can be represented as follows:

[0089] Example 17: The difference between Example 17 and Example 1 is as follows: Na₂SiO₃·9H₂O was added to distilled water to prepare a solution A with a concentration of 0.27 mol / L; a metal nitrate (nickel nitrate and zirconium nitrate in a molar ratio of 0.9:0.1) was added to distilled water to prepare a solution C with a concentration of 0.45 mol / L; other steps and parameters were the same as in Example 1, and the resulting catalyst can be represented as...

[0090] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that Na₂SiO₃·9H₂O was added to distilled water to prepare a solution A with a concentration of 0.09 mol / L; nickel nitrate was added to distilled water to prepare a solution C with a concentration of 0.15 mol / L; other step parameters were the same as in Example 1, and the resulting catalyst can be represented as...

[0091] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the highly active nickel-based catalyst was prepared using a traditional co-precipitation method. The specific preparation method is as follows:

[0092] (1) Add Na2SiO3·9H2O to distilled water to prepare a solution A with a concentration of 0.25 mol / L; add sulfuric acid to distilled water to prepare a solution B with a concentration of 0.3 mol / L; add metallic nitrate (molar ratio of nickel nitrate to cerium nitrate is 0.85:0.15) to distilled water to prepare a solution C with a concentration of 0.25 mol / L; add Na2CO3 to distilled water to prepare a solution D with a concentration of 0.3 mol / L.

[0093] (2) Add 100ml of solution A, turn on mechanical stirring at 300r / min, heat the water bath to 70℃, add solution B dropwise through a constant pressure dropping funnel to stabilize the pH of the system at 8-9, continue stirring for 30min after the addition is complete, let stand and age for 1h to form silica gel.

[0094] (3) Add 100 ml of solution C to the above silica gel, stir evenly, and continue to add 100 ml of solution D through a constant pressure dropping funnel. Maintain the system temperature at 60℃ and pH value at 8-9. After the addition is complete, stir the reaction for 2 hours and let it stand for 2 hours to obtain the precipitate.

[0095] (4) The precipitate was centrifuged, washed with distilled water until neutral, dried, and ground into powder to obtain dry precipitate powder. Then, 10% of the mass of the dry precipitate powder of boehmite and 40% of the mass of the dry precipitate powder of distilled water were added and mixed thoroughly until a paste was formed. The paste was extruded into strips with a diameter of about 2 mm, dried at room temperature, and then dried in an oven. After drying, the temperature was increased to 400℃ at 5℃ / min and calcined for 4 h to obtain the catalyst precursor.

[0096] (5) The catalyst precursor was loaded into a fixed bed reactor, heated to 500°C, and reduced for 3 hours under H2 gas flow (flow rate 100 ml / min) to obtain a nickel-based catalyst.

[0097] Performance testing:

[0098] 1. Prepare 4,4'-diaminodiphenyl ether by continuous catalytic hydrogenation of 4,4'-dinitrodiphenyl ether according to the following steps:

[0099] A fixed-bed reactor was used, with a nickel-based highly active catalyst packed in a constant-temperature layer in the middle of the reactor. The temperature inside the catalyst bed was monitored by thermocouples. The liquid phase material, a mixture of 4,4'-dinitrodiphenyl ether and N,N-dimethylacetamide, was pumped to the preheater through a stainless steel pipe with an inner diameter of 0.3 mm by a horizontal flow pump. Hydrogen gas was introduced into the preheater through a pressure reducing valve and a gas mass flow meter to mix with the liquid phase material. After being preheated to 50-150°C in the preheater, it entered the reactor. The reaction temperature was 50-150°C. A condenser and a storage tank were connected to the bottom of the reactor, and the system pressure was controlled by a back pressure valve. The reaction product was separated into gas and liquid phases. The liquid phase material was collected, and N,N-dimethylacetamide was recovered by vacuum distillation. The remaining product was recrystallized in ethanol to obtain 4,4'-diaminodiphenyl ether.

[0100] 1. In a reaction mixture of 4,4'-dinitrodiphenyl ether and N,N-dimethylacetamide (mass ratio) of 1:5, the feed rate of the liquid phase material is 0.20 h⁻¹ of the catalyst volume. -1 The catalytic performance of the catalysts prepared in Examples 1-17 and Comparative Examples 1-2 was tested under the conditions of ,4,4'-dinitrodiphenyl ether:H2 (molar ratio) = 1:20, pressure 1.5 MPa, and reaction temperature 110 °C. The experimental results are shown in Table 1.

[0101] Table 1 Catalytic performance of different catalysts

[0102]

[0103]

[0104] 2. The effects of reaction temperature, reaction pressure, liquid phase feed rate, reactant concentration and hydrogen molar ratio on the catalytic performance of the high-efficiency nickel-based catalyst system prepared in Example 1 were investigated. The experimental results are shown in Table 2.

[0105] Table 2 Effect of reaction process conditions on catalytic performance

[0106]

[0107]

[0108] 3. Catalyst lifetime test: The optimal process conditions determined in performance test 2 were: reaction temperature 100℃, pressure 1.0MPa, and liquid phase material feed rate of 0.10h / catalyst volume. -1 The high-efficiency nickel-based catalyst prepared in Example 1 was tested with a DNDPE:DMAC (mass ratio) of 1:4 and a DNDPE:H2 (molar ratio) of 1:25. The stability of 4,4'-dinitrodiphenyl ether in the hydrogenation reaction to prepare 4,4'-diaminodiphenyl ether is shown in Table 3.

[0109] Table 3 Catalyst Stability

[0110]

[0111]

[0112] Performance Analysis:

[0113] As can be seen from the data in Table 1, the conversion rate of 4,4'-dinitrodiphenyl ether (DNDPE) in all examples and comparative examples reached 100%, but the selectivity and yield showed significant differences: the selectivity of the examples ranged from 78.6% to 93.6%, and the yields were also between 78.6% and 93.6%, while the selectivity of Comparative Example 1 (without the second metal Ce) was only 56.8%, and that of Comparative Example 2 (traditional coprecipitation method) was 67.4%. The core reason for this difference lies in the difference in the microstructure of the catalyst and the synergistic effect of the components. The core of the excellent performance of the examples lies in the "highly dispersed Ni active center + SiO2-CeO2 / ZrO2 composite support" structure constructed by the "dual-membrane dispersion microreactor series + stepwise precipitation" process. The dual-membrane dispersion microreactor transforms the solution into micron-sized droplets through the cross-flow shear of the microporous filter membrane, enabling instantaneous and uniform mixing of sodium silicate and sulfuric acid, and metal ions and sodium carbonate. This completely avoids the aggregation of silicate gel and Ni active components caused by local uneven concentration in the traditional coprecipitation method (Comparative Example 2). This efficient hybridization mode allows Ni 2+ Ce 3+ / Zr 4+ Simultaneous nucleation and growth on the silica gel surface enables highly dispersed Ni without the need for surfactants. Each Ni nanoparticle can independently serve as an active site, increasing the number of effective sites for H2 dissociation and enhancing substrate adsorption through coordination with DNDPE nitro groups. This promotes the directional reaction between active hydrogen species (H*) and nitro groups, reducing side reactions such as aromatic ring hydrogenation and excessive nitro group reduction. Simultaneously, the composite support formed by SiO2 and CeO2 / ZrO2 plays a crucial synergistic role: the porous structure of SiO2 provides ample specific surface area, fixing Ni particles through steric hindrance and preventing aggregation during the reaction; while CeO2... 3+ / Ce 4+The variable valence state can undergo electron transfer with Ni, reducing the activation energy of Ni's dissociation from H2 and enhancing Ni's adsorption selectivity for nitro groups. This is the core reason why the selectivity of the example (containing Ce) is significantly higher than that of Comparative Example 1 (without Ce) and Example 12 (Zr replacing Ce). Due to the lack of electronic regulation by Ce, the catalytic selectivity of Ni in Comparative Example 1 relies solely on its own characteristics, and the proportion of side reactions increases significantly. In Comparative Example 2, due to the traditional stirring and mixing, Ni agglomerates and CeO2 cannot be uniformly doped, and the synergistic effect of the composite support is destroyed, resulting in a selectivity of only 72% of that of Example 1.

[0114] The optimized process conditions data in Table 2 show that the catalyst in Example 1 is optimal at 50-150℃, 0.3-3.0 MPa, and 0.05-1.0 h⁻¹. -1 High conversion rates were maintained across a wide range of process parameters, including feed rates, with an optimal yield of 98.7%, demonstrating strong process adaptability. This advantage stems from the high degree of matching between the catalyst structure and the catalytic mechanism. From a mass transfer perspective, the porous SiO2 composite support of the catalyst in the examples provided unobstructed channels for the diffusion of substrate, product, and active hydrogen, effectively reducing mass transfer resistance even at relatively high feed rates (1.0 h⁻¹). -1 Even at lower pressures (0.8 MPa), DNDPE can still rapidly reach the Ni active sites, and H* can also combine with nitro groups in a timely manner, avoiding the accumulation of side reactions caused by poor mass transfer. From the perspective of catalytic activity, the highly dispersed Ni active centers and the electronic synergy of Ce allow the catalyst to achieve efficient reduction of nitro groups at low temperatures (80°C) and suppress excessive hydrogenation at high temperatures (150°C) through Ce regulation, maintaining a yield of 85.2%. In contrast, traditional catalysts often suffer from insufficient activity at low temperatures and a surge in side reactions at high temperatures due to uneven dispersion of active components, making it difficult to adapt to a wide range of process conditions. This synergistic effect of "efficient mass transfer + controllable activity" allows the catalyst in this example to match different operating parameter requirements in industrial production, significantly improving the practicality of the process.

[0115] The catalyst stability data in Table 3 show that the catalyst in Example 1 maintained a 100% conversion rate and a stable yield of 97.6%-99.0% after 600 hours of continuous operation, far exceeding the cycle life of traditional nickel-based catalysts. This stability stems from the catalyst's structural design to resist deactivation. Firstly, the highly dispersed Ni active centers constructed using the dual-film dispersion process are difficult to aggregate due to the steric hindrance effect of the composite support. The porous framework of SiO2 and the doping sites of CeO2 / ZrO2 form "anchoring points," firmly fixing the Ni nanoparticles and preventing the loss of active sites due to particle aggregation during the reaction. Secondly, the pseudoboehmite binder not only ensures the mechanical strength of the catalyst, but its surface hydroxyl groups can also form chemical bonds with the support and Ni particles, further enhancing structural stability. Compared with catalysts prepared by traditional coprecipitation methods (such as Comparative Example 2), Ni particles tend to agglomerate and grow during the reaction due to poor initial dispersion, resulting in a continuous reduction of active sites and a significant decrease in stability. In contrast, the catalyst in this example achieves high-efficiency catalysis over a long period through a positive cycle of "preparation process - structural stability - long-lasting performance", which fully meets the core requirements of continuous industrial production.

[0116] In summary, the superior performance of the catalysts in the examples is not due to a single factor, but rather the result of the combined effects of "precise preparation process of dual-membrane dispersed microreactor", "highly dispersed Ni active centers", "synergistic effect of SiO2-CeO2 / ZrO2 composite support" and "structural stabilization effect of pseudoboehmite". This fundamentally solves the pain points of traditional catalysts such as "uneven dispersion, insufficient synergy, and poor stability", and achieves breakthroughs in selectivity, process adaptability and long-term stability.

[0117] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a highly active nickel-based catalyst, characterized in that, Includes the following steps: (1) Adding Na2SiO3·9H2O to distilled water yields solution A; adding sulfuric acid to distilled water yields solution B; adding metal nitrate to distilled water yields solution C; adding Na2CO3 to distilled water yields solution D. (2) After solution A is introduced into the first microporous membrane reactor at a certain flow rate, it is mixed with solution B. The pH value of the mixed solution is adjusted to 8-9 by adjusting the flow rate of solution B. Then it is introduced into a polytetrafluoroethylene tube with an inner diameter of 3 mm. After the temperature is raised to 70℃, it reacts to form silica gel. After mixing with solution C at a certain flow rate through a T-shaped tee, it is introduced into a polytetrafluoroethylene tube with an inner diameter of 3 mm as a continuous phase and enters the second microporous membrane reactor. Solution D is mixed with it as a dispersed phase at a certain flow rate and then introduced into a polytetrafluoroethylene tube with an inner diameter of 3 mm. After reacting in a water bath at 60℃, the precipitate is collected. (3) The precipitate was centrifuged, washed with distilled water until neutral, dried, and ground into powder to obtain dry precipitate powder. Then, boehmite and distilled water were added and mixed thoroughly and ground into a paste. The paste was extruded into strips with a diameter of about 2 mm, dried at room temperature, and then dried in an oven. After drying, the temperature was increased to 300-500℃ at 5℃ / min and calcined for 4 h to obtain catalyst precursor. (4) The catalyst precursor is loaded into a fixed bed reactor, heated to 450-550℃, and reduced for 3h under H2 gas flow to obtain a high-efficiency nickel-based catalyst.

2. The method for preparing the highly active nickel-based catalyst according to claim 1, characterized in that, In (1), the concentration of Na2SiO3·9H2O in solution A is 0.01-0.5 mol / L; the concentration of sulfuric acid in solution B is 0.01-0.5 mol / L; the concentration of metal nitrate in solution C is 0.01-0.5 mol / L; and the concentration of Na2CO3 in solution D is 0.01-0.5 mol / L. Metal nitrate refers to a mixture of nickel nitrate and cerium nitrate or zirconium nitrate in a molar ratio of 0.85-0.95:0.05-0.

15.

3. The method for preparing the highly active nickel-based catalyst according to claim 1, characterized in that, The flow rates of solutions A, B, and C in (2) are 1-30 ml / min; the pore size of the microporous membrane reactor is 0.1-50 μm.

4. The method for preparing the highly active nickel-based catalyst according to claim 1, characterized in that, In step (3), the amount of boehmite added is 5-15% of the weight of the dried precipitate powder, and the amount of distilled water added is 30-60% of the weight of the dried precipitate powder.

5. The method for preparing the highly active nickel-based catalyst according to claim 1, characterized in that, The flow rate of H2 gas in (4) is 100 ml / min.

6. The highly active nickel-based catalyst obtained by the method for preparing the highly active nickel-based catalyst according to any one of claims 1-5, characterized in that, The highly active nickel-based catalyst is represented as follows: Where A represents the molar concentration of metallic nitrate in solution C during the preparation process, x, y, and z represent the molar ratios of Ni in nickel nitrate in solution C to SiO2 converted from Na2SiO3·9H2O in solution A through sulfuric acid acidification and calcination, and M in solution C, respectively; M represents Ce or Zr in metallic nitrate, h represents the calcination temperature, and r represents the reduction temperature.

7. The application of the highly active nickel-based catalyst according to claim 6 in the continuous catalytic hydrogenation preparation of 4,4'-diaminodiphenyl ether, characterized in that, Includes the following steps: A fixed-bed reactor was used, with a nickel-based highly active catalyst packed in a constant-temperature layer in the middle of the reactor. The temperature inside the catalyst bed was monitored by thermocouples. The liquid phase material, a mixture of 4,4'-dinitrodiphenyl ether and N,N-dimethylacetamide, was pumped to the preheater through a stainless steel pipe with an inner diameter of 0.3 mm by a horizontal flow pump. Hydrogen gas was introduced into the preheater through a pressure reducing valve and a gas mass flow meter to mix with the liquid phase material. After being preheated to 50-150°C in the preheater, it entered the reactor. The reaction temperature was 50-150°C. A condenser and a storage tank were connected to the bottom of the reactor, and the system pressure was controlled by a back pressure valve. The reaction product was separated into gas and liquid phases. The liquid phase material was collected, and N,N-dimethylacetamide was recovered by vacuum distillation. The remaining product was recrystallized in ethanol to obtain 4,4'-diaminodiphenyl ether.

8. The application of the highly active nickel-based catalyst according to claim 7 in the continuous catalytic hydrogenation preparation of 4,4'-diaminodiphenyl ether, characterized in that, The 4,4'-dinitrodiphenyl ether and N,N-dimethylacetamide are present in a weight ratio of 1:3-10.

9. The application of the highly active nickel-based catalyst according to claim 7 in the continuous catalytic hydrogenation preparation of 4,4'-diaminodiphenyl ether, characterized in that, The molar ratio of 4,4'-dinitrodiphenyl ether to hydrogen is 1:5-50.

10. The application of the highly active nickel-based catalyst according to claim 7 in the continuous catalytic hydrogenation preparation of 4,4'-diaminodiphenyl ether, characterized in that, The rate at which the liquid phase material enters the reactor is 0.05-1.0 h⁻¹ of the catalyst volume. -1 The system pressure is 0.3-3.0 MPa.

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