Hollow s-1 encapsulated ni particle catalyst and preparation method and application thereof

Abstract

The application provides a hollow S-1 encapsulated Ni particle catalyst for catalyzing maleic anhydride hydrogenation to prepare succinic anhydride and a preparation method thereof. The hollow S-1 encapsulated Ni particle catalyst is prepared by using a template agent, a silicon source and water as raw materials to prepare Silicalite-1 molecular sieve (S-1 molecular sieve), hydrothermally modifying the S-1 molecular sieve with an alkali solution to form S-1 molecular sieve with a hollow structure (HoS-1 molecular sieve), loading a Ni source on the HoS-1 molecular sieve carrier through an impregnation method, and then drying, calcining and reducing to obtain the hollow S-1 encapsulated Ni particle catalyst. Compared with the prior art, the hollow S-1 encapsulated Ni particle catalyst for catalyzing maleic anhydride hydrogenation to prepare succinic anhydride has the advantages of short preparation process period, low cost, mild hydrogenation reaction condition, effective prevention of active Ni particle shedding due to the hollow outer wall, and excellent catalytic activity and stability.

Description

Technical Field

[0001] This invention belongs to the technical field of catalyst design and liquid-phase reaction optimization. Specifically, it relates to a highly active and stable hollow S-1 encapsulated Ni particle catalyst, its preparation method, and its application in the hydrogenation reaction of maleic anhydride. Background Technology

[0002] Succinic acid is a natural organic acid widely found in the tissues and cells of various organisms. Succinic acid (anhydride) and its derivatives have been widely used in the pharmaceutical, food, agricultural, and organic chemical industries. With increasing environmental protection requirements, biodegradable plastic polybutylene succinate (PBS), using succinic acid and its derivative butanediol as the main raw material, has also received extensive research. Industrially, succinic acid in China is mainly produced using electrochemical processes. However, electrochemical processes are highly polluting, costly, and have low yields, making it difficult to meet the growing market demand for succinic acid. Against this backdrop, the process of preparing succinic anhydride from maleic anhydride (maleic anhydride) by catalytic hydrogenation has attracted widespread attention. Furthermore, in recent years, the production method of maleic anhydride has transitioned from benzene oxidation to the more efficient n-butane oxidation method, reducing the raw material cost of the maleic anhydride hydrogenation process for preparing succinic anhydride, thus giving it broader application prospects.

[0003] Hydrogenation catalysts are diverse, and compared to expensive noble metal-based catalysts, highly active and stable non-noble metal catalysts have attracted widespread attention from researchers. Co / Al₂O₃, Ni / H-BEA, Cu / CeO₂, and Cu-ZnO-SiO₂ non-noble metal catalysts have been applied to the hydrogenation of maleic anhydride. Among them, Ni-based catalysts exhibit hydrogenation performance closest to that of noble metals and are widely used in the maleic anhydride hydrogenation reaction. The choice of support in hydrogenation catalysts is also crucial. How to improve the activity and stability of catalysts and reduce Ni particle shedding by regulating the interaction between metallic Ni and the support is of great research significance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a hollow S-1 encapsulated Ni particle catalyst, its preparation method, and its application. Ni particles are loaded onto the inner surface of a hollow S-1 molecular sieve, and the Ni particles are anchored using an MFI-configured molecular sieve shell, providing a method to prevent Ni particle detachment by adding an external protective layer. Furthermore, the ordered pore structure of the outer shell can also promote the diffusion of reactants to the vicinity of the active Ni particles, improving the catalyst activity. This catalyst, along with its modification and preparation methods, is simple, cost-effective, and requires minimal equipment. The prepared catalyst exhibits high maleic anhydride conversion, high succinic anhydride selectivity, and high stability in the liquid-phase hydrogenation reaction of maleic anhydride.

[0005] To address the shortcomings of existing technologies, the technical solution provided by this invention is as follows:

[0006] A method for preparing a hollow S-1 encapsulated Ni particle catalyst includes the following steps:

[0007] (1) MFI-configured Silicalite-1 molecular sieve, namely S-1 molecular sieve, was prepared using template agent, silicon source and water as raw materials;

[0008] (2) The S-1 molecular sieve is hydrothermally modified with an alkaline solution to form a uniform and stable S-1 molecular sieve with a hollow structure, namely HoS-1 molecular sieve.

[0009] (3) The Ni source is loaded onto the hollow HoS-1 molecular sieve support by impregnation, and then dried, baked, calcined and reduced to obtain the hollow S-1 encapsulated Ni particle catalyst, i.e. Ni / HoS-1 catalyst.

[0010] The present invention is further configured such that, in step (1), an all-silica S-1 molecular sieve is prepared by a hydrothermal method, the template agent is tetrapropylammonium hydroxide solution (TPAOH), the silicon source is tetraethyl orthosilicate (TEOS), and the water is preferably ultrapure water. Specifically, the following steps are included:

[0011] S1. Precrystallization stage: Mix the template agent, silicon source and ultrapure water in a beaker and stir at room temperature for 1 to 6 hours to fully hydrolyze the silicon source;

[0012] S2. Crystallization stage: The hydrolyzed mixture is transferred from the beaker to a polytetrafluoroethylene liner and then sealed in a stainless steel hydrothermal reactor for crystallization reaction. The reaction temperature is 160-190℃ and the reaction time is 12-72h.

[0013] S3. Separation and washing: Centrifuge the crystallized suspension and wash it multiple times until the pH of the washing solution is neutral;

[0014] S4. Drying stage: Dry the separated and washed white product in an oven at a temperature of 100-120℃ for 10-20 hours.

[0015] S5. Calcination stage: The dried product is calcined in a muffle furnace at a temperature of 500-600℃ for 5-10 hours to obtain S-1 molecular sieve.

[0016] The present invention is further configured such that, in step (1), the molar ratio of the silicon source, template agent and water is 1SiO2:x TPAOH:y H2O, where x is 0.2 to 0.5 and y is 20 to 80.

[0017] The present invention is further configured such that, in step (2), the S-1 molecular sieve is hydrothermally modified by alkaline solution, specifically including the following steps:

[0018] S1. Hydrothermal stage: The S-1 molecular sieve, alkali source and water are mixed evenly in a polytetrafluoroethylene liner, and then sealed in a stainless steel hydrothermal reactor for hydrothermal modification reaction. The hydrothermal modification temperature is 160-190℃ and the time is 12-72h.

[0019] S2. Separation and washing: The suspension obtained by hydrothermal modification is centrifuged and washed until the pH of the washing solution is neutral;

[0020] S3. Drying stage: Dry the separated and washed white product in an oven at a temperature of 100-120℃ for 10-20 hours.

[0021] S4. Calcination stage: The dried product is calcined in a muffle furnace at a temperature of 500-600℃ for 5-10 hours to obtain HoS-1 molecular sieve with a hollow structure.

[0022] The present invention is further configured such that, in step (2), the alkali source is NaOH, TPAOH, or a mixture of the two.

[0023] The present invention is further configured such that, in step (2), the molar ratio of the S-1 molecular sieve, the alkali source, and water is 1SiO2:mOH. - :n H2O, wherein m = 0.2 to 0.3, more preferably 0.25; n = 10 to 40, preferably 20.

[0024] The present invention is further configured such that, in step (3), the Ni source is loaded onto the HoS-1 molecular sieve using an equal-volume impregnation method, specifically including the following steps:

[0025] S1. Loading stage: A certain amount of the HoS-1 molecular sieve is placed in a crucible, and a nickel salt solution prepared according to the loading amount is added dropwise to the crucible and stirred to form a paste-like suspension; wherein the loading amount is based on the total amount of HoS-1 molecular sieve, and the nickel metal element content is 3 to 10 wt% based on the metal element content, preferably 5 to 10 wt%, more preferably 5 wt%.

[0026] S2. Drying stage: The crucible containing the sample is left open at room temperature to initially evaporate the moisture for 12-24 hours. Then it is transferred to an oven for drying at 100-120℃ for 10-20 hours.

[0027] S3. Calcination stage: The dried product is calcined in a muffle furnace at a temperature of 500-600℃ for 5-10 hours to calcine the nickel salt into gray nickel oxide.

[0028] S4. Reduction Stage: The calcined gray powder is loaded into a quartz boat and placed in a tube furnace, through which H₂ is introduced. 2- Ar mixed gas was heated to 450-750℃ at a rate of 1-10℃ / min for 2-10 h for reduction. After reduction, the temperature was lowered to obtain black encapsulated Ni wNi / HoS-1 catalyst, where w is 3-10 wt%.

[0029] The present invention is further configured such that, in step (3), the nickel source is selected from nickel nitrate or nickel chloride.

[0030] The present invention is further configured such that, in step (3), the reducing atmosphere is preferably 5 vol.% to 30 vol.% H. 2- Ar mixture, more preferably 10 vol.% H 2- Ar mixture gas.

[0031] A second aspect of the present invention is to provide a hollow S-1 encapsulated Ni particle catalyst, which is prepared by the method for preparing the hollow S-1 encapsulated Ni particle catalyst, wherein the average particle size of the catalyst is 200-500 nm.

[0032] A third aspect of the present invention is to provide an application of the hollow S-1 encapsulated Ni particle catalyst for the hydrogenation reaction of maleic anhydride, including the hydrogenation reaction of maleic anhydride to prepare succinic anhydride.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The preparation method of this invention has a short preparation cycle, low cost, and mild reaction conditions. The hollow outer wall can effectively prevent the active Ni particles from detaching. The Ni / HoS-1 catalyst with hollow encapsulated Ni particles prepared can directly catalyze the hydrogenation of maleic anhydride to succinic anhydride under low-temperature liquid phase conditions. It has excellent catalytic activity, high maleic anhydride conversion and succinic anhydride selectivity, and retains high catalytic activity and good stability even after multiple recycling. Attached Figure Description

[0035] Figure 1 SEM image of the catalyst prepared in Example 1 of the present invention;

[0036] Figure 2 SEM image of the catalyst prepared in Example 2 of this invention;

[0037] Figure 3SEM image of the catalyst prepared in Example 3 of the present invention;

[0038] Figure 4 SEM image of the catalyst prepared in Example 4 of this invention;

[0039] Figure 5 SEM image of the catalyst prepared in Example 5 of this invention;

[0040] Figure 6 SEM image of the catalyst prepared in Example 6 of the present invention;

[0041] Figure 7 TEM image of the catalyst prepared in Example 2 of the present invention;

[0042] Figure 8 TEM image of the catalyst prepared in Comparative Example 1 of the present invention;

[0043] Figure 9 This is a TEM image of the catalyst prepared in Comparative Example 2 of the present invention;

[0044] Figure 10 This is a TEM image of the catalyst prepared in Comparative Example 3 of the present invention. Detailed Implementation

[0045] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. It should be understood that the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar with the art.

[0046] Example 1

[0047] (1) S-1 molecular sieves with MFI configuration were synthesized by hydrothermal method with a feed ratio of 1SiO2:0.3TPAOH:20H2O. The specific operation was as follows: 7.63g TPAOH and 13.44g ultrapure water were added to a 100mL beaker and stirred for 30min to mix evenly. Then, 10.42g TEOS was slowly added dropwise to the system, and stirring was continued for 3h until TEOS was completely hydrolyzed. The solution was then transferred to a polytetrafluoroethylene liner, sealed in a hydrothermal reactor, and crystallized in a dynamic oven at 170℃ for 48h. Finally, the mother liquor was centrifuged to obtain a white product, which was washed, dried, and calcined in a muffle furnace at 550℃ for 6h to obtain S-1 molecular sieves.

[0048] (2) S-1 molecular sieve was modified using tetrapropylammonium hydroxide (TPAOH) solution as the alkali source, with a feed ratio of 1SiO2:0.25TPAOH:20H2O. The specific operation was as follows: 1g of the above S-1 molecular sieve, 2.11g of 40wt% TPAOH aqueous solution and 5.39g of ultrapure water were added to 50mL of polytetrafluoroethylene liner, ultrasonically dispersed for 30min, and then sealed in a hydrothermal reactor. The mixture was hydrothermally modified in an oven at 170℃ for 24h. Finally, the product solution was centrifuged to obtain a white product, which was washed, dried and calcined in a muffle furnace at 550℃ for 6h to obtain HoS-1 molecular sieve.

[0049] (3) A 5wt% Ni / HoS-1 catalyst precursor was prepared by an equal-volume impregnation method. The nickel source used was a nickel nitrate solution. After impregnation, the catalyst was allowed to stand at room temperature for 24 h to ensure sufficient contact. Then, it was dried overnight in an oven at 110 °C and finally calcined in a muffle furnace at 550 °C for 6 h to obtain the nickel-based catalyst precursor. The above catalyst precursor was placed in a tube furnace for reduction and activation. The reducing gas was a 10 vol.% H2-Ar mixture. The heating rate was 5 °C / min, and the temperature was maintained at 550 °C for 3 h. Then, it was cooled to room temperature to obtain a highly active and stable Ni / HoS-1 catalyst.

[0050] The SEM image of the Ni / HoS-1 catalyst is shown below. Figure 1 As shown, the structure is regular and the particle size distribution is uniform. The average particle size is measured to be approximately 210 nm.

[0051] Example 2

[0052] (1) S-1 molecular sieves with MFI configuration were synthesized by hydrothermal method with a feed ratio of 1SiO2:0.3TPAOH:40H2O. The specific operation was as follows: 7.63g TPAOH and 31.46g ultrapure water were added to a 100mL beaker and stirred for 30min to mix evenly. Then, 10.42g TEOS was slowly added dropwise to the system, and stirring was continued for 3h until TEOS was completely hydrolyzed. The solution was then transferred to a polytetrafluoroethylene liner, sealed in a hydrothermal reactor, and crystallized in a dynamic oven at 170℃ for 48h. Finally, the mother liquor was centrifuged to obtain a white product, which was washed, dried, and calcined in a muffle furnace at 550℃ for 6h to obtain S-1 molecular sieves.

[0053] (2) S-1 molecular sieve was modified using tetrapropylammonium hydroxide (TPAOH) solution as the alkali source, with a feed ratio of 1SiO2:0.25TPAOH:20H2O. The specific operation was as follows: 1g of the above S-1 molecular sieve, 2.11g of 40wt% TPAOH aqueous solution and 5.39g of ultrapure water were added to 50mL of polytetrafluoroethylene liner, ultrasonically dispersed for 30min, and then sealed in a hydrothermal reactor. The mixture was hydrothermally modified in an oven at 170℃ for 24h. Finally, the product solution was centrifuged to obtain a white product, which was washed, dried and calcined in a muffle furnace at 550℃ for 6h to obtain HoS-1 molecular sieve.

[0054] (3) A 5wt% Ni / HoS-1 catalyst precursor was prepared by an equal-volume impregnation method. The nickel source used was a nickel nitrate solution. After impregnation, the catalyst was allowed to stand at room temperature for 24 h to ensure sufficient contact. Then, it was dried overnight in an oven at 110 °C and finally calcined in a muffle furnace at 550 °C for 6 h to obtain the nickel-based catalyst precursor. The above catalyst precursor was placed in a tube furnace for reduction and activation. The reducing gas was a 10 vol.% H2-Ar mixture. The heating rate was 5 °C / min, and the temperature was maintained at 550 °C for 3 h. Then, it was cooled to room temperature to obtain a highly active and stable Ni / HoS-1 catalyst.

[0055] The SEM image of the Ni / HoS-1 catalyst is shown below. Figure 2 As shown, the structure is regular and the particle size distribution is uniform. The average particle size is measured to be approximately 315 nm.

[0056] Example 3

[0057] (1) S-1 molecular sieves with MFI configuration were synthesized by hydrothermal method with a feed ratio of 1SiO2:0.3TPAOH:80H2O. The specific operation was as follows: 7.63g TPAOH and 67.5g ultrapure water were added to a 100mL beaker and stirred for 30min to mix evenly. Then, 10.42g TEOS was slowly added dropwise to the system, and stirring was continued for 3h until TEOS was completely hydrolyzed. The solution was then transferred to a polytetrafluoroethylene liner, sealed in a hydrothermal reactor, and crystallized in a dynamic oven at 170℃ for 48h. Finally, the mother liquor was centrifuged to obtain a white product, which was washed, dried, and calcined in a muffle furnace at 550℃ for 6h to obtain S-1 molecular sieves.

[0058] (2) S-1 molecular sieve was modified using tetrapropylammonium hydroxide (TPAOH) solution as the alkali source, with a feed ratio of 1SiO2:0.25TPAOH:20H2O. The specific operation was as follows: 1g of the above S-1 molecular sieve, 2.11g of 40wt% TPAOH aqueous solution and 5.39g of ultrapure water were added to 50mL of polytetrafluoroethylene liner, ultrasonically dispersed for 30min, and then sealed in a hydrothermal reactor. The mixture was hydrothermally modified in an oven at 170℃ for 24h. Finally, the product solution was centrifuged to obtain a white product, which was washed, dried and calcined in a muffle furnace at 550℃ for 6h to obtain HoS-1 molecular sieve.

[0059] (3) A 5wt% Ni / HoS-1 catalyst precursor was prepared by an equal-volume impregnation method. The nickel source used was a nickel nitrate solution. After impregnation, the catalyst was allowed to stand at room temperature for 24 h to ensure sufficient contact. Then, it was dried overnight in an oven at 110 °C and finally calcined in a muffle furnace at 550 °C for 6 h to obtain the nickel-based catalyst precursor. The above catalyst precursor was placed in a tube furnace for reduction and activation. The reducing gas was a 10 vol.% H2-Ar mixture. The heating rate was 5 °C / min, and the temperature was maintained at 550 °C for 3 h. Then, it was cooled to room temperature to obtain a highly active and stable Ni / HoS-1 catalyst.

[0060] The SEM image of the Ni / HoS-1 catalyst is shown below. Figure 3 As shown, the structure is regular and the particle size distribution is uniform. The average particle size is measured to be approximately 520 nm.

[0061] Example 4

[0062] (1) S-1 molecular sieves with MFI configuration were synthesized by hydrothermal method with a feed ratio of 1SiO2:0.3TPAOH:40H2O. The specific operation was as follows: 7.63g TPAOH and 31.46g ultrapure water were added to a 100mL beaker and stirred for 30min to mix evenly. Then, 10.42g TEOS was slowly added dropwise to the system, and stirring was continued for 3h until TEOS was completely hydrolyzed. The solution was then transferred to a polytetrafluoroethylene liner, sealed in a hydrothermal reactor, and crystallized in a dynamic oven at 170℃ for 48h. Finally, the mother liquor was centrifuged to obtain a white product, which was washed, dried, and calcined in a muffle furnace at 550℃ for 6h to obtain S-1 molecular sieves.

[0063] (2) S-1 molecular sieve was modified using tetrapropylammonium hydroxide (TPAOH) solution as the alkali source, with a feed ratio of 1SiO2:0.2TPAOH:20H2O. The specific operation was as follows: 1g of the above S-1 molecular sieve, 1.69g of 40wt% TPAOH aqueous solution and 5.64g of ultrapure water were added to 50mL of polytetrafluoroethylene liner, and after being ultrasonically dispersed for 30min, the mixture was sealed in a hydrothermal reactor and hydrothermally modified in an oven at 170℃ for 24h. Finally, the product solution was centrifuged to obtain a white product, which was washed, dried and calcined in a muffle furnace at 550℃ for 6h to obtain HoS-1 molecular sieve.

[0064] (3) A 10 wt% Ni / HoS-1 catalyst precursor was prepared by an equal-volume impregnation method. The nickel source used was a nickel nitrate solution. After impregnation, the catalyst was allowed to stand at room temperature for 24 h to ensure sufficient contact. Then, it was dried overnight in an oven at 110 °C and finally calcined in a muffle furnace at 550 °C for 6 h to obtain the nickel-based catalyst precursor. The above catalyst precursor was placed in a tube furnace for reduction and activation. The reducing gas was a 10 vol.% H2-Ar mixture. The heating rate was 5 °C / min, and the temperature was maintained at 550 °C for 3 h. Then, it was cooled to room temperature to obtain a highly active and stable Ni / HoS-1 catalyst.

[0065] The SEM image of the Ni / HoS-1 catalyst is shown below. Figure 4 ,and Figure 2 Similarly, it has a regular structure and uniform particle size distribution. The average particle size was measured to be approximately 320 nm.

[0066] Example 5

[0067] (1) S-1 molecular sieves with MFI configuration were synthesized by hydrothermal method with a feed ratio of 1SiO2:0.3TPAOH:40H2O. The specific operation was as follows: 7.63g TPAOH and 31.46g ultrapure water were added to a 100mL beaker and stirred for 30min to mix evenly. Then, 10.42g TEOS was slowly added dropwise to the system, and stirring was continued for 3h until TEOS was completely hydrolyzed. The solution was then transferred to a polytetrafluoroethylene liner, sealed in a hydrothermal reactor, and crystallized in a dynamic oven at 170℃ for 48h. Finally, the mother liquor was centrifuged to obtain a white product, which was washed, dried, and calcined in a muffle furnace at 550℃ for 6h to obtain S-1 molecular sieves.

[0068] (2) S-1 molecular sieve was modified using tetrapropylammonium hydroxide (TPAOH) solution as the alkali source, with a feed ratio of 1SiO2:0.3TPAOH:20H2O. The specific operation was as follows: 1g of the above S-1 molecular sieve, 2.53g of 40wt% TPAOH aqueous solution and 5.14g of ultrapure water were added to 50mL of polytetrafluoroethylene liner, ultrasonically dispersed for 30min, and then sealed in a hydrothermal reactor. The mixture was hydrothermally modified in an oven at 170℃ for 24h. Finally, the product solution was centrifuged to obtain a white product, which was washed, dried and calcined in a muffle furnace at 550℃ for 6h to obtain HoS-1 molecular sieve.

[0069] (3) A 5wt% Ni / HoS-1 catalyst precursor was prepared by an equal-volume impregnation method. The nickel source used was a nickel nitrate solution. After impregnation, the catalyst was allowed to stand at room temperature for 24 h to ensure sufficient contact. Then, it was dried overnight in an oven at 110 °C and finally calcined in a muffle furnace at 550 °C for 6 h to obtain the nickel-based catalyst precursor. The above catalyst precursor was placed in a tube furnace for reduction and activation. The reducing gas was a 10 vol.% H2-Ar mixture. The heating rate was 5 °C / min, and the temperature was maintained at 550 °C for 3 h. Then, it was cooled to room temperature to obtain a highly active and stable Ni / HoS-1 catalyst.

[0070] The SEM image of the Ni / HoS-1 catalyst is shown below. Figure 5 The particle size distribution is uniform, but the increased alkalinity caused some particles to develop crystal surface defects, forming a bowl-shaped structure and a small number of crystalline wafers. The average particle size was measured to be approximately 350 nm.

[0071] Example 6

[0072] (1) S-1 molecular sieves with MFI configuration were synthesized by hydrothermal method with a feed ratio of 1SiO2:0.3TPAOH:40H2O. The specific operation was as follows: 7.63g TPAOH and 31.46g ultrapure water were added to a 100mL beaker and stirred for 30min to mix evenly. Then, 10.42g TEOS was slowly added dropwise to the system, and stirring was continued for 3h until TEOS was completely hydrolyzed. The solution was then transferred to a polytetrafluoroethylene liner, sealed in a hydrothermal reactor, and crystallized in a dynamic oven at 170℃ for 48h. Finally, the mother liquor was centrifuged to obtain a white product, which was washed, dried, and calcined in a muffle furnace at 550℃ for 6h to obtain S-1 molecular sieves.

[0073] (2) S-1 molecular sieve was modified using tetrapropylammonium hydroxide (TPAOH) solution as the alkali source, with a feed ratio of 1SiO2:0.25TPAOH:20H2O. The specific operation was as follows: 1g of the above S-1 molecular sieve, 2.11g of 40wt% TPAOH aqueous solution and 5.39g of ultrapure water were added to 50mL of polytetrafluoroethylene liner, ultrasonically dispersed for 30min, and then sealed in a hydrothermal reactor. The mixture was hydrothermally modified in an oven at 170℃ for 24h. Finally, the product solution was centrifuged to obtain a white product, which was washed, dried and calcined in a muffle furnace at 550℃ for 6h to obtain HoS-1 molecular sieve.

[0074] (3) A 3wt% Ni / HoS-1 catalyst precursor was prepared by an equal-volume impregnation method. The nickel source used was a nickel nitrate solution. After impregnation, the catalyst was allowed to stand at room temperature for 24 h to ensure sufficient contact. Then, it was dried overnight in an oven at 110 °C and finally calcined in a muffle furnace at 550 °C for 6 h to obtain the nickel-based catalyst precursor. The above catalyst precursor was placed in a tube furnace for reduction and activation. The reducing gas was a 10 vol.% H2-Ar mixture. The heating rate was 5 °C / min, and the temperature was maintained at 550 °C for 3 h. Then, it was cooled to room temperature to obtain a highly active and stable Ni / HoS-1 catalyst.

[0075] The SEM image of the Ni / HoS-1 catalyst is shown below. Figure 6 ,and Figure 2 Similarly, it has a regular structure and uniform particle size distribution. The average particle size was measured to be approximately 320 nm.

[0076] Comparative Example 1

[0077] (1) S-1 molecular sieves with MFI configuration were synthesized by hydrothermal method with a feed ratio of 1SiO2:0.3TPAOH:40H2O. The specific operation was as follows: 7.63g TPAOH and 31.46g ultrapure water were added to a 100mL beaker and stirred for 30min to mix evenly. Then, 10.42g TEOS was slowly added dropwise to the system, and stirring was continued for 3h until TEOS was completely hydrolyzed. The solution was then transferred to a polytetrafluoroethylene liner, sealed in a hydrothermal reactor, and crystallized in a dynamic oven at 170℃ for 48h. Finally, the mother liquor was centrifuged to obtain a white product, which was washed, dried, and calcined in a muffle furnace at 550℃ for 6h to obtain S-1 molecular sieves.

[0078] (2) A 5 wt% Ni / S-1 catalyst precursor was prepared by an equal-volume impregnation method. The nickel source used was a nickel nitrate solution. After impregnation, the catalyst was allowed to stand at room temperature for 24 h to ensure sufficient contact. Then, it was dried overnight in an oven at 110 °C and finally calcined in a muffle furnace at 550 °C for 6 h to obtain the nickel-based catalyst precursor. The above catalyst precursor was placed in a tube furnace for reduction activation. The reducing gas was a 10 vol.% H2-Ar mixture. The heating rate was 5 °C / min, and the temperature was maintained at 550 °C for 3 h. Then, it was cooled to room temperature to obtain the Ni / S-1 catalyst of Comparative Example 1.

[0079] Figure 8 The image is a TEM image of Comparative Example 1. It can be seen from the image that the supported Ni particles are unevenly dispersed and have significant differences in particle size. However, from Example 2 (… Figure 7 In the catalyst, the formation of internal cavities in the molecular sieve is clearly visible. Thanks to this hollow structure, the supported Ni particles are uniformly distributed on the inner surface of the molecular sieve layer, and the particle size distribution of the Ni particles is more uniform. In addition, the shedding of Ni particles during the reaction is effectively prevented by the protection of the outer shell of the molecular sieve.

[0080] Comparative Example 2

[0081] (1) Fumed silica was modified using tetrapropylammonium hydroxide (TPAOH) solution as the alkali source, with a feed ratio of 1SiO2:0.25TPAOH:20H2O. The specific operation was as follows: 1g of commercially available fumed silica, 2.11g of 40wt% TPAOH aqueous solution and 5.39g of ultrapure water were added to 50mL of polytetrafluoroethylene liner. After being ultrasonically dispersed for 30min, the mixture was sealed in a hydrothermal reactor and hydrothermally modified in an oven at 110℃ for 24h. Finally, the product solution was centrifuged to obtain a white product, which was washed, dried and calcined in a muffle furnace at 550℃ for 6h to obtain SiO2-A.

[0082] (2) A 5wt% Ni / SiO2-A catalyst precursor was prepared by an equal-volume impregnation method. The nickel source used was a nickel nitrate solution. After impregnation, the catalyst was allowed to stand at room temperature for 24 h to ensure sufficient contact. It was then dried overnight in an oven at 110 °C and finally calcined in a muffle furnace at 550 °C for 6 h to obtain the nickel-based catalyst precursor. The catalyst precursor was then reduced and activated in a tube furnace using a 10 vol.% H2-Ar mixture as the reducing gas. The heating rate was 5 °C / min, and the temperature was maintained at 550 °C for 3 h. Subsequently, it was cooled to room temperature to obtain the Ni / SiO2-A catalyst. TEM images are shown below. Figure 9 As shown, a hollow structure was not formed inside the catalyst, the supported Ni particles were unevenly dispersed, and the particle size difference was large.

[0083] Comparative Example 3

[0084] (1) MCM-41 molecular sieve was modified using tetrapropylammonium hydroxide (TPAOH) solution as the alkali source, with a feed ratio of 1SiO2:0.25TPAOH:20H2O. The specific operation was as follows: 1g of commercially available MCM-41 molecular sieve, 2.11g of 40wt% TPAOH aqueous solution and 5.39g of ultrapure water were added to 50mL of polytetrafluoroethylene liner. After being ultrasonically dispersed for 30min, the mixture was sealed in a hydrothermal reactor and hydrothermally modified in an oven at 110℃ for 24h. Finally, the product solution was centrifuged to obtain a white product, which was washed, dried and calcined in a muffle furnace at 550℃ for 6h to obtain MCM-41-A.

[0085] (2) A 5 wt% Ni / MCM-41-A catalyst precursor was prepared by an equal-volume impregnation method. The nickel source used was a nickel nitrate solution. After impregnation, the catalyst was allowed to stand at room temperature for 24 h to ensure sufficient contact. It was then dried overnight in an oven at 110 °C and finally calcined in a muffle furnace at 550 °C for 6 h to obtain the nickel-based catalyst precursor. The catalyst precursor was then reduced and activated in a tube furnace using a 10 vol.% H2-Ar mixture as the reducing gas. The heating rate was 5 °C / min, and the temperature was maintained at 550 °C for 3 h. Subsequently, it was cooled to room temperature to obtain the Ni / MCM-41-A catalyst. TEM images are shown below. Figure 10 As shown, a hollow structure was not formed inside the catalyst, the supported Ni particles were unevenly dispersed, and the particle size difference was large.

[0086] Example 7 Catalyst Evaluation

[0087] In this embodiment, all catalyst evaluations were conducted using a 100 mL high-pressure liquid-phase stirred tank reactor. The specific operating procedure is as follows: 0.1 g of the reduced and activated catalyst, 2 g of maleic anhydride, 18 g of tetrahydrofuran (as solvent), and a magnetic stir bar were added to a 100 mL polytetrafluoroethylene liner and stirred for 10 min to fully dissolve the raw materials. The liner was then sealed in the high-pressure reactor. The reactor was first purged with pure Ar for 10 min to completely remove air, followed by purging with pure H2 for 10 min to remove residual Ar. After closing the outlet valve, the high-pressure reactor was purged with H2 to 3 MPa, the inlet valve was closed, and the temperature control and stirring switches were turned on to begin the hydrogenation reaction. No further H2 was added during the reaction. The standard reaction conditions were 110 °C, 3 MPa hydrogen, and a stirring speed of 500 rpm.

[0088] The evaluation results for Examples 1-6 and Comparative Examples 1-3 are shown in the table below:

[0089] Table 1. Evaluation data of maleic anhydride hydrogenation for each catalyst

[0090]

[0091] Catalyst stability tests were conducted on Examples 2 and 1, respectively. Fresh catalysts were recovered and reused multiple times, and the conversion rate and selectivity were recorded for each test. The evaluation results are shown in the table below:

[0092] Table 2. Stability data of the catalyst in Example 2 for maleic anhydride hydrogenation evaluation.

[0093]

[0094] Table 3. Stability data of maleic anhydride hydrogenation evaluation of catalyst in Comparative Example 1.

[0095]

[0096] The Ni / HoS-1 catalyst with hollow encapsulated Ni particles prepared by this invention can directly catalyze the hydrogenation of maleic anhydride to succinic anhydride under low-temperature liquid phase conditions. It has excellent catalytic activity, high maleic anhydride conversion rate and succinic anhydride selectivity, and still has high catalytic activity and good stability after multiple recycling.

[0097] This application provides a detailed description, the purpose of which is to enable those skilled in the art to understand and implement the content of this application, but it should not be used to limit the scope of protection of this application. All equivalent changes or modifications made in accordance with the spirit and essence of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing a hollow S-1 encapsulated Ni particle catalyst, characterized in that, Includes the following steps: (1) Silicalite-1 molecular sieve, i.e. S-1 molecular sieve, was prepared using template agent, silicon source and water as raw materials; (2) The S-1 molecular sieve is hydrothermally modified with an alkaline solution to form an S-1 molecular sieve with a hollow structure, namely HoS-1 molecular sieve. The hydrothermal modification temperature is 160~190 ℃ and the time is 12~72 h. (3) The Ni source is loaded onto the HoS-1 molecular sieve support by impregnation, and then dried, calcined and reduced to obtain the hollow S-1 encapsulated Ni particle catalyst, i.e. Ni / HoS-1 catalyst; In step (2), the S-1 molecular sieve is mixed evenly with an alkali source and water and then subjected to hydrothermal modification. The alkali source is NaOH, TPAOH, or a mixture of both. The molar ratio of the S-1 molecular sieve, alkali source, and water is 1:m(SiO2:m(OH)). - : n H2O, where m = 0.2~0.3; n = 10~40; In the Ni / HoS-1 catalyst, the loading is based on the total amount of HoS-1 molecular sieve, and the nickel metal content is 3~10 wt% based on the amount of elemental metal.

2. The preparation method according to claim 1, characterized in that, In step (1), the S-1 molecular sieve is prepared by hydrothermal method, including the following steps: The template agent, silicon source, and water were mixed and stirred to fully hydrolyze the silicon source. The hydrolyzed mixture was then subjected to a crystallization reaction in a hydrothermal reactor at a temperature of 160–190 °C for 12–72 h. The resulting suspension was centrifuged, washed, dried, and calcined to obtain S-1 molecular sieve.

3. The preparation method according to claim 2, characterized in that, In step (1), the template agent is tetrapropylammonium hydroxide solution, and the silicon source is tetraethyl orthosilicate; the molar ratio of silicon source, template agent and water is 1 SiO2:x TPAOH: y H2O, where x is 0.2~0.5 and y is 20~80.

4. The preparation method according to claim 1, characterized in that, Step (2) includes the following steps: The S-1 molecular sieve was mixed evenly with an alkali source and water, and then subjected to a hydrothermal modification reaction in a hydrothermal reactor. The hydrothermally modified suspension was centrifuged and washed. After drying and calcination, the HoS-1 molecular sieve with a hollow structure was obtained.

5. The preparation method according to claim 1, characterized in that, In step (3), the Ni source is loaded onto the HoS-1 molecular sieve using an equal-volume impregnation method, which includes the following steps: A nickel salt solution was added dropwise to the HoS-1 molecular sieve, and the mixture was stirred to form a paste-like suspension. The suspension was allowed to stand at room temperature to initially evaporate the water, followed by drying and calcination. The calcined product was then subjected to H... 2- The catalyst was reduced in an Ar mixed atmosphere and then cooled to obtain wNi / HoS-1 catalyst, where w is 3~10 wt%.

6. The preparation method according to claim 5, characterized in that, In step (3), the nickel source is selected from nickel nitrate or nickel chloride; the standing time is 12-24 h.

7. The preparation method according to claim 5, characterized in that, In step (3), the reducing atmosphere is 5 vol.% ~ 30 vol.% H. 2- Ar mixed gas; the reduction conditions are: heating to 450~750 ℃ ​​at a heating rate of 1~10 ℃ / min for 2~10 h.

8. The preparation method according to claim 7, characterized in that, In step (3), the reducing atmosphere is 10 vol.% H. 2- Ar mixture gas.

9. A hollow S-1 encapsulated Ni particle catalyst, characterized in that, The catalyst is prepared by any one of the preparation methods described in claims 1-8, and the average particle size of the catalyst is 200-500 nm.

10. An application of the hollow S-1 encapsulated Ni particle catalyst as described in claim 9, characterized in that, Used for the hydrogenation reaction of maleic anhydride, including the hydrogenation reaction of maleic anhydride to prepare succinic anhydride.

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