A catalyst for continuously preparing succinic anhydride by liquid phase hydrogenation of maleic anhydride

Abstract

The application provides a catalyst for continuously preparing succinic anhydride through liquid-phase hydrogenation of maleic anhydride, which comprises an alumina carrier, a Ni active component, a first additive and a second additive supported on the alumina carrier, and a SiO2 protective film coated on the alumina carrier; the content of the Ni active component is 10-28 wt%, the content of the first additive is 3-12 wt%, the content of the second additive is 0.5-5 wt%, and the content of the SiO2 protective film is 0.5-8 wt% based on 100% of the mass of the carrier; the Ni active component, the first additive and the second additive are loaded on the carrier by impregnating the carrier after roasting with a complex impregnation solution containing Ni, the first additive, the second additive and a complexing agent; the carrier loaded with the Ni active component, the first additive and the second additive is impregnated into an impregnation solution containing organic silicon after drying, roasting and reduction, and then is subjected to drying, hydrothermal reaction, drying and roasting to obtain the catalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a catalyst for the continuous preparation of succinic anhydride by liquid-phase hydrogenation of maleic anhydride. Background Technology

[0002] Succinic anhydride, also known as succinic anhydride, has the molecular formula C4H4O3. It is a colorless, plate-like or needle-like crystal, widely used as an important organic synthesis raw material in pharmaceuticals, pesticides, food, fine chemicals, and synthetic resins. With the guidance of national environmental protection policies and the increasing environmental awareness of the public, the demand for biodegradable materials is growing rapidly. Succinic anhydride and its hydrolysis product, succinic acid, can both serve as important monomers for the fully biodegradable material PBS; therefore, their future demand is substantial.

[0003] Currently, there are two main methods for producing succinic anhydride: succinic acid dehydration and maleic anhydride catalytic hydrogenation. Succinic acid dehydration can be further divided into direct dehydration and chemical dehydration, both of which suffer from drawbacks such as long process routes and numerous steps. Catalytic hydrogenation of maleic anhydride can be divided into melt method and solvent method. The melt method avoids the need for solvents, thus preventing product purification difficulties and environmental pollution. However, the development of the catalyst system and the control of reaction conditions are technical challenges in the hydrogenation reaction. The solvent method involves first dissolving maleic anhydride in a solvent before hydrogenation. Since the hydrogenation of maleic anhydride to succinic anhydride is a strongly exothermic reaction, the addition of a solvent can: ① dissolve maleic anhydride; ② facilitate the removal of reaction heat, mitigating reaction conditions; and ③ facilitate the desorption of the hydrogenation product, succinic anhydride, improving hydrogenation selectivity. This method produces succinic anhydride with high selectivity and is currently the most promising method for preparing succinic anhydride.

[0004] Catalysts for the hydrogenation of maleic anhydride to succinic anhydride using solvent methods are mainly divided into noble metal Pd-based catalysts and non-noble metal Ni / Cu-based catalysts. Patents EP 0691335 and Ru 2058311 disclose a catalyst for the selective hydrogenation of maleic anhydride to succinic anhydride using noble metal Pd, with a Pd content as high as 2–10 wt%. Using this catalyst at a reaction pressure of 4–6 MPa, the selectivity for succinic anhydride is 90–95%. However, due to the high noble metal loading of this catalyst, its expensive production cost makes it difficult to apply to practical industrial production.

[0005] Patent CN 103007929 A discloses a Pd-based catalyst prepared by colloidal deposition, its preparation method, and its application. When used for the hydrogenation of maleic anhydride, this catalyst exhibits a maleic anhydride conversion rate ≥99.99% and a succinic anhydride selectivity ≥99.99%. The catalyst is prepared by adding protective agents such as polyvinylpyrrolidone (PVP) or polyvinyl alcohol (PVA) and using ethylene glycol or polyethylene glycol as a reducing agent, resulting in a highly dispersible catalyst that demonstrates high succinic anhydride selectivity and stability when used for maleic anhydride hydrogenation. However, the catalyst product is in powder form, and during the deposition process, Pd salt can precipitate not only on the support but also easily in the solution, leading to a significant loss rate of the active component Pd. This results in a substantial increase in production costs, making it difficult to scale up for industrial application.

[0006] Patent CN 105597742 A discloses an impregnated Pd catalyst used for the hydrogenation of maleic anhydride under the following conditions: maleic anhydride solution concentration of 5–50 wt%, reaction temperature of 40–160 °C, reaction pressure of 0.2–2.0 MPa, H2 / anhydride molar ratio of 2–0.02, and maleic anhydride mass hourly space velocity of 0.1–3.0 h⁻¹. -1 The conversion rate of maleic anhydride is ≥99.9%, and the selectivity of succinic anhydride is ≥99.4%. Although the catalyst prepared by the impregnation method reduces the loss rate of active metals, the reduction temperature of this catalyst is as high as 500℃, which causes the active metals to aggregate, reduces the dispersibility of the active metals, and increases the cost of the catalyst.

[0007] Patent CN 105833863 A discloses a supported Pd catalyst, characterized by a palladium content of 0.25–1 wt%, with the remainder being a support. The support is selected from one of SiO2, Al2O3, activated carbon, and HZSM-5 molecular sieve. This catalyst achieves high dispersion of active metal Pd through ultrasonic dispersion and precise control via reduction treatment. When used for maleic anhydride hydrogenation, the prepared catalyst achieves 100% conversion of the feedstock and a selectivity of ≥99% for succinic anhydride. The high Pd loading (0.25–1 wt%) indicates a high level of active Pd, resulting in higher industrial application costs.

[0008] Patent CN 106669745 B discloses a catalyst using porous ceramic as a support to support the noble metal Pd. The porous ceramic support is first treated with a citric acid solution, allowing the solution to quickly form a uniform film on the support surface during tin chloride impregnation. This improves the dispersion of palladium chloride on the support surface, thereby enhancing its activity and stability. When used for maleic anhydride hydrogenation, this catalyst operates at a reaction temperature of 90–150°C, a liquid hourly space velocity of 0.1–1, and a hydrogen-to-anhydride molar ratio of 50–200. However, the active palladium loading of this catalyst reaches 1–5%, resulting in high production costs.

[0009] The above patents, through different preparation processes, have produced noble metal Pd-based catalysts for the selective hydrogenation of maleic anhydride, exhibiting high conversion rates and selectivity for succinic anhydride. Simultaneously, Pd possesses a certain degree of acid resistance, preventing the loss of active metal during catalyst use and thus ensuring good catalyst stability. However, all of these catalysts share the problem of high Pd content. Due to the high price of noble metal Pd, their application costs are significantly higher than those of non-noble metal catalysts. Therefore, researchers have also invested considerable effort in the development of non-noble metal catalysts.

[0010] Patent CN 103769105 B discloses a Ni-based catalyst with a metal active component supported on a SiO2 support. The support is prepared by mixing diatomaceous earth with silica sol, wherein the diatomaceous earth needs to be pre-treated by soaking in an acidic solution. The catalyst's main active component is Ni, and the auxiliary agent is at least one selected from Cr, Mo, W, Mn, Re, Ru, Co, Rh, Pt, Pd, Ag, Cu, Mg, La, Ce, K, Ca, Sn, and Ge. The nickel content is 3–8 wt%, the auxiliary agent content is 0.1–10 wt%, and the diatomaceous earth content in the catalyst support is 50–80 wt%. A γ-butyrolactone solution with a maleic anhydride content of 5–50 wt% is used as a raw material in a fixed-bed process, with a reaction temperature of 60–180℃, a reaction pressure of 0.5–6.0 MPa, and a liquid hourly space velocity of 0.5–4.0 h⁻¹. -1 The maleic anhydride was continuously hydrogenated to prepare succinic anhydride under certain conditions. The SiO2 support used has good acid resistance, but the pore size of the support itself is small, which is not conducive to the mass transfer of the maleic anhydride hydrogenation reaction. The utilization rate of the active component inside the catalyst is low, and the active component Ni is easily lost in the acidic environment, resulting in a decrease in the stability of use.

[0011] Patent CN 101502802 A discloses a supported catalyst, using SiO2, Al2O3, or SiO2-Al2O3 as a support, nickel as the active component, and at least one of Cr, Mo, W, Mn, Re, Ru, Co, Rh, Pt, Pd, Cu, Mg, La, Ce, K, Ca, Sn, and Ge as an auxiliary agent. Its key feature is that the active component nickel content is 13–20 wt%, the auxiliary agent content is 1–7 wt%, and the remainder is the support. When this catalyst is used for the continuous hydrogenation of maleic anhydride to produce succinic anhydride, the reaction pressure is 0.9–10 MPa, the reaction temperature is 60–180 °C, the conversion rate of maleic anhydride is ≥99.98%, and the selectivity of succinic anhydride is ≥98.85%. When this catalyst is used for maleic anhydride hydrogenation, its space velocity is low, resulting in high energy consumption for subsequent separation and increasing the cost of the separation process. At the same time, the support has a low water absorption rate, and the addition of ammonia during the impregnation process increases the volume of the impregnation liquid, requiring multiple impregnations to complete the catalyst loading. This causes the active metal to clog the pores, reducing the dispersion of the active metal and increasing the complexity of the operation.

[0012] Patent CN 104607204 A discloses a catalyst prepared by a single-stage, equal-volume impregnation method using Ni and Cu as active components, preferably Fe, Zn, Co, Mn, Cr, Mo, Pd, Pt, and La-based metals as additives, and preferably Na, K, Mg, and Ca as additives, with Al2O3, SiO2, or Al2O3-SiO2 as the support. The catalyst has a Ni content of 10–18%, a Cu content of 3–8%, additive one content of 0.03–3%, and additive two content of 0.5–2%. This catalyst, with the active metals supported on the Al2O3, SiO2, or Al2O3-SiO2 support forming an alloy, exhibits acid corrosion resistance. However, the Al2O3 support used lacks acid resistance, resulting in poor catalyst stability. When used in maleic anhydride fixed-bed or isothermal bed hydrogenation, the maleic anhydride space velocity is low, increasing the operating cost.

[0013] Patent CN 103769117 A discloses a fixed-bed maleic anhydride hydrogenation catalyst using activated carbon as a support, Co and Ni as active components, and Mo, W, Fe, Cu, and Zn as promoters. Due to the strong acid resistance of activated carbon, the support is not easily corroded, effectively preventing support collapse. Simultaneously, the interaction of multiple active components enhances the activity of maleic anhydride hydrogenation and the selectivity of succinic anhydride. While the activated carbon support used in this catalyst exhibits good acid resistance, the catalyst calcination process requires an inert atmosphere, placing high demands on the calcination furnace. Furthermore, the support must be impregnated with a 5%–40% nitric acid solution and a γ-butyrolactone solution before being used as a support, increasing industrial production costs. Additionally, the pore size of the activated carbon support is relatively small, resulting in a lower space velocity of maleic anhydride.

[0014] Patent CN 111957338 A discloses a highly stable catalyst for the hydrogenation of maleic anhydride to succinic anhydride and its preparation method. This catalyst is prepared using a hydrotalcite-like hybrid nitrogen-containing organic compound as a precursor, with a Ni-M bimetallic component as the active component, Al2O3 as the support, and coated with an N-doped C film. The catalyst structure is Ni-M-Al2O3@CN. The structure, where the active metal and the support share the same surface and are coated within the @CN film, effectively prevents corrosion of the catalyst by water or acid in the reaction system, thus avoiding damage to the catalyst structure. However, this also prevents maleic anhydride from contacting the active metal, significantly reducing the hydrogenation activity of maleic anhydride. Furthermore, the N-doping and C-film coating process lacks selectivity, hindering the selective hydrogenation of maleic anhydride.

[0015] Among the non-precious metal catalysts prepared by the above patents, the use of Ni as the active component alone in a weakly acidic environment during long-term operation presents the problem of active component loss. The loss of Ni in an acidic environment can be avoided by forming an alloy. As for the support, the use of acid-resistant supports, such as α-Al2O3, SiO2, activated carbon, and silicon carbide, has the problems of small pore size, low internal metal utilization, and the need for multiple impregnations when loading high content of active metal, which reduces the dispersion of active metal.

[0016] As can be seen from current invention patents, in existing maleic anhydride hydrogenation catalysts, when using the noble metal Pd, the catalyst exhibits good activity and hydrogenation selectivity, and is acid-resistant. However, it generally suffers from a high active metal content, resulting in high catalyst usage costs. While non-noble metal Ni can achieve the performance of noble metal catalysts, the active metal Ni is easily lost in acidic environments. Furthermore, the supports used are also prone to structural collapse in water or acidic environments, while acid-resistant supports suffer from small pore sizes and low dispersion of active metals. Summary of the Invention

[0017] The purpose of this invention is to provide a catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride. By adding a complexing agent, the dispersion of the active metal is improved, which in turn helps to improve the pore structure of the catalyst. After reduction, the catalyst is impregnated with organosilicon. After hydrolysis, the organosilicon forms a protective film, which achieves directional coverage of the protective film on the surface of the support without covering the active metal sites. Therefore, the catalyst can ensure hydrogenation activity while avoiding corrosion of the support by the acid in the system, thus preventing the catalyst from affecting its stability.

[0018] To achieve the above objectives, the present invention provides a catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to prepare succinic anhydride. The catalyst comprises an alumina support, a Ni active component supported on the alumina support, a first auxiliary agent and a second auxiliary agent, and a SiO2 protective film coated on the alumina support. The first auxiliary agent is at least one selected from Mo, Cu, and Ag; the second auxiliary agent is at least one selected from Sn, La, Zn, Co, Mg, K, Ca, Rh, and Ru; and the Ni active component content is 10-2% based on 100% of the support mass. The catalyst is prepared by impregnating a calcined support loaded with Ni active components, the first auxiliary agent, and the second auxiliary agent with a complexing impregnation solution containing Ni, the first auxiliary agent, the second auxiliary agent, and a complexing agent. The support loaded with Ni active components, the first auxiliary agent, and the second auxiliary agent is dried, calcined and reduced, and then impregnated in an impregnation solution containing organosilicon. After drying and hydrothermal reaction, it is dried and calcined again to obtain the catalyst.

[0019] The calcination conditions for the alumina carrier are not specifically limited and are conventional techniques in the field. Those skilled in the art can make adjustments according to the actual situation. Preferably, the calcination conditions for alumina in this invention are calcination treatment at 450-700℃ for 4-12 hours.

[0020] The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride described in this invention does not specifically limit the specific surface area, pore volume, pore size, etc., of the alumina support. Those skilled in the art can select these parameters according to actual conditions. Preferably, the specific surface area of ​​the alumina support described in this invention is 200–400 m². 2 / g, with a pore volume of 0.6–1.4 mL / g; preferably, the alumina support has a specific surface area of ​​280–350 m² / g. 2 / g, with a pore volume of 0.8~1.2mL / g.

[0021] The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride described in this invention uses a complexing agent that is commonly used in the art and is not specifically limited thereto. Preferably, the complexing agent is at least one selected from ethylenediaminetetraacetic acid (EDTA), ethylenediamine (EDA), propylenediamine (PDA), butanediamine (BDA), hexamethylenediamine (HDA), citrate (CA), nitric acid triacetic acid (NTA), cyclohexanediaminetetraacetic acid (CyDTA), and ethylene glycol (EG). When using EDTA, ammonia should be used to promote its dissolution.

[0022] The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to prepare succinic anhydride described in this invention does not specifically limit the impregnation method and conditions of the alumina support with the complexing impregnation solution, as these are conventional techniques in the art. Those skilled in the art can select and adjust these methods according to actual conditions. Impregnation can be completed in one step or in multiple steps, preferably in one step. In cases of multiple impregnations, drying is required after each impregnation, and the drying conditions are the same as those for drying after a single impregnation. Preferably, the impregnation time of the alumina support with the complexing impregnation solution in this invention is 1–4 hours. The drying and calcination conditions are not specifically limited and are conventional techniques in the art, which those skilled in the art can select according to actual conditions. Preferably, the drying temperature is 80–150°C, the drying time is 4–12 hours, and the calcination temperature is 350–600°C, with a calcination time of 3–8 hours.

[0023] The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride described in this invention does not specifically limit the reduction conditions, which are conventional techniques in the field. Those skilled in the art can select and adjust the conditions according to actual circumstances. Preferably, the reduction temperature in this invention is 350–480°C, the reduction pressure is atmospheric pressure to 0.5 MPa, and the reducing gas space velocity is 300–1500 h⁻¹. -1 The restoration time is 5 to 40 hours.

[0024] The catalyst for the continuous preparation of succinic anhydride by liquid-phase hydrogenation of maleic anhydride according to the present invention uses organosilicon, which is a commonly used substance in the art. The present invention does not limit the type of organosilicon, and those skilled in the art can select it according to the actual situation. Preferably, the organosilicon in the present invention is at least one of tetraethyl orthosilicate, tetramethoxysilane, tetraethoxysilane and methyltrioxysilane, preferably tetraethyl orthosilicate and / or tetramethoxysilane.

[0025] The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride described in this invention is prepared by dissolving the organosilicon in an organic solvent. The organic solvent is a commonly used substance in the art, and this invention does not specifically limit its use. Those skilled in the art can select the appropriate solvent based on the actual situation. Preferably, the organic solvent in this invention is at least one selected from methanol, ethanol, propanol, butanol, and acetone, with ethanol and / or methanol being more preferred. The organic solvent is an anhydrous organic solvent that has undergone dehydration treatment.

[0026] The catalyst for the continuous preparation of succinic anhydride by liquid-phase hydrogenation of maleic anhydride described in this invention does not specifically limit the impregnation method and conditions in the impregnation solution containing organosilicon. These are conventional techniques in the field, and those skilled in the art can select and adjust them according to actual conditions. Preferably, the impregnation time is 10-50 hours. After impregnation, drying is performed. This invention does not specifically limit the drying conditions, which are conventional techniques in the field. Those skilled in the art can select and adjust them according to actual conditions. Preferably, the drying conditions in this invention are drying at a temperature range of 70-130°C for 5-30 hours.

[0027] The catalyst for the continuous preparation of succinic anhydride by liquid-phase hydrogenation of maleic anhydride according to the present invention uses a hydrothermal reaction, which is a conventional technique in the art. The conditions for the hydrothermal reaction are not specifically limited. Preferably, the hydrothermal reaction conditions in the present invention are hydrolysis in an acidic aqueous solution at 90-120°C for 1-3 hours. The acid in the acidic aqueous solution is at least one of hydrochloric acid, formic acid, and acetic acid, and the acid concentration is 0.1-2 wt%, preferably 0.3-1.0 wt%.

[0028] The catalyst for the continuous preparation of succinic anhydride by liquid-phase hydrogenation of maleic anhydride described in this invention uses conventional techniques in the field for drying and calcination after hydrothermal reaction. The specific conditions for drying and calcination are not limited. Preferably, the drying conditions in this invention are drying at 80-150°C for 3-8 hours and calcination conditions are calcination at 400-700°C for 3-7 hours under an inert atmosphere.

[0029] In this invention, when preparing the complex impregnation solution containing Ni, a first auxiliary agent, and a second auxiliary agent, Ni, the first auxiliary agent, and the second auxiliary agent are introduced by adding precursors containing Ni, the first auxiliary agent, and the second auxiliary agent. The precursors containing Ni, the first auxiliary agent, and the second auxiliary agent are all commonly used substances in the art. For example, the Ni-containing precursor can be nickel nitrate, nickel chloride, nickel sulfate, nickel formate, nickel acetate, nickel oxalate, nickel citrate, etc.; the precursor containing the first auxiliary agent can be a soluble salt containing Mo, Cu, and Ag, specifically such as ammonium molybdate, copper nitrate, copper chloride, copper sulfate, silver nitrate, silver fluoride, silver chlorate, silver perchlorate, etc.; the precursor containing the second auxiliary agent can be a soluble salt containing Sn, La, Zn, Co, Mg, K, Ca, Rh, and Ru, specifically such as nitrates, chlorides, or sulfates.

[0030] In the catalytic hydrogenation of maleic anhydride to succinic anhydride, the catalyst of this invention, after activation, is used in a fixed-bed reactor at a pressure of 1.5–4.0 MPa and a maleic anhydride mass hourly space velocity of 0.1–1.5 h⁻¹. -1Succinic anhydride is prepared by continuous hydrogenation of maleic anhydride using a maleic anhydride solvent method under reaction conditions of 2-30 molar ratio of hydrogen to anhydride and 50-150℃. The reaction product is separated by distillation to obtain succinic anhydride, and the solvent is recycled after recovery. Succinic anhydride can be hydrolyzed to obtain succinic acid.

[0031] The catalyst activation conditions are: activation temperature 200–300℃, pressure atmospheric pressure to 0.5 MPa, and space velocity 300–600 h⁻¹. -1 Activation time: 5–20 hours.

[0032] Under the above reaction conditions, maleic anhydride has a conversion rate of ≥99.5% and a selectivity of ≥99.5% for succinic anhydride.

[0033] The concentration of maleic anhydride solution is 5–25 wt%.

[0034] The solvent for dissolving maleic anhydride is at least one of xylene, toluene, propylene oxide, cyclohexane, ethyl acetate, dioxane, methyl acetone, dimethyl sulfoxide, dimethyl succinate, diethyl succinate, acetone, γ-butyrolactone, and tetrahydrofuran; preferably, the solvent for dissolving maleic anhydride is at least one of ethyl acetate, dimethyl succinate, diethyl succinate, γ-butyrolactone, tetrahydrofuran, and dioxane.

[0035] Beneficial effects of this invention:

[0036] Alumina is a commonly used catalyst support for hydrogenation. When used in the selective hydrogenation of maleic anhydride, it inhibits the hydrogenation activity of C=O, which is beneficial for improving hydrogenation selectivity. The maleic anhydride solvent process contains trace amounts of water or acid. During long-term operation of the catalyst, this can easily cause hydration and framework collapse of the alumina support. Furthermore, the presence of acid can corrode the active metal Ni, leading to its loss.

[0037] This invention utilizes a complexing agent to achieve high dispersibility of the active metal. Simultaneously, the oxidation of the complexing agent during calcination expands the pores, increasing the mass transfer efficiency of the catalyst channels. After calcination, the active metal oxide is reduced to zero valence. Therefore, during the hydrolysis of organosilicon, the generated Si-OH (Si-O) reacts with the hydroxyl groups on the support surface or the active Al... 3+ In combination, selectively coating the alumina support without coating the active metal gives the support acid resistance. Furthermore, the active metal Ni obtained by this method forms an alloy or solid solution with the auxiliary metal, which improves the stability of the catalyst in acidic environments while maintaining its hydrogenation activity and selectivity.

[0038] In this invention, Sn, Mo, Cu, and Ag also act as separators, preventing nickel grain growth during calcination, improving the catalyst's thermal stability, increasing nickel dispersion, lowering the reaction temperature, and enhancing Ni's water resistance. Sn increases Ni's electronegativity, making water adsorption difficult, thus improving the catalyst's water resistance. Meanwhile, Zn, Co, and La help Sn, Mo, Cu, and Ag further enhance Ni's electronegativity, improving succinic anhydride desorption, increasing hydrogenation selectivity, and raising the formation temperature of the deep hydrogenation byproduct γ-butyrolactone. The Mg, K, and Ca promoters in this invention can adjust the catalyst's acidity and improve hydrogenation selectivity. Detailed Implementation

[0039] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0040] The catalyst of this invention was characterized using the following methods during preparation: the active metal content of the catalyst was determined using an A240FS atomic absorption spectrometer; and the silica content of the protective film was detected using a ZSX Primus II X-ray fluorescence spectrometer.

[0041] The contents of maleic anhydride feedstock and hydrogenation products were analyzed using an Agilent 6890A gas chromatograph.

[0042] The raw material maleic anhydride is type I solid maleic anhydride with a content of ≥99.5wt%. Specific implementation examples:

[0044] Example 1

[0045] The catalyst preparation process in this embodiment is as follows:

[0046] (1) The pore volume of the No. 1 alumina carrier after calcination at 600℃ for 4 hours was 0.81 mL / g, and the specific surface area was 316 m². 2 / g, weigh out 100g for later use;

[0047] (2) Weigh 91g of ethylenediaminetetraacetic acid and dissolve it in 80g of concentrated ammonia water. Stir to obtain a clear solution. Then weigh 49.6g of nickel nitrate, 15.2g of copper nitrate, 2.3g of tin tetrachloride, 2.4g of lanthanum nitrate, and 9.2g of magnesium nitrate and add them to the above solution. Stir to obtain a clear solution.

[0048] (3) The prepared impregnation solution is impregnated onto the carrier in equal volume and left to stand for 2 hours, then dried at 100°C for 10 hours to obtain semi-finished product A.

[0049] (4) The semi-finished product A was calcined at 550℃ for 3 hours. The calcined sample was then reduced in a hydrogen atmosphere. The reduction conditions were to maintain a hydrogen space velocity of 500 h⁻¹. -1 After heating to 450℃ at normal pressure, the reduction was completed after 15 hours, yielding semi-finished product B.

[0050] (5) Weigh 8.7g of tetraethyl orthosilicate, dissolve it in 86.8g of anhydrous ethanol, and stir to obtain a clear solution.

[0051] (6) Immerse an equal volume of tetraethyl orthosilicate alcohol solution onto semi-finished product B, let it stand for 24 hours, and then dry it at 80°C for 24 hours to obtain semi-finished product C.

[0052] (7) Take the semi-finished product C and place it in a hydrothermal reactor. Use an acidic aqueous solution with a formic acid concentration of 0.5wt% for hydrothermal treatment. The feed rate is 30g / h. Hydrothermal treatment is carried out at 110℃ for 1.5h to obtain the semi-finished product D.

[0053] (8) The semi-finished product D was dried at 120°C for 4 hours and calcined at 500°C for 4 hours under a nitrogen atmosphere to obtain the catalyst.

[0054] The catalyst prepared in Example 1 was determined by atomic absorption spectrometry and XRF fluorescence spectrometry, respectively, wherein the content of Ni was 10.0%, Cu was 4.0%, Sn was 1.0%, La was 1.0%, Mg was 1.5%, and SiO2 was 2.5%.

[0055] Comparative Example 1

[0056] The catalyst preparation process of this comparative example is as follows: the preparation conditions are the same as those in Example 1, except that it is not supported on organosilicon;

[0057] (1) The pore volume of the No. 1 alumina carrier after calcination at 600℃ for 4 hours was 0.81 mL / g, and the specific surface area was 316 m². 2 / g, weigh out 100g for later use;

[0058] (2) Weigh 91g of ethylenediaminetetraacetic acid and dissolve it in 80g of concentrated ammonia water. Stir to obtain a clear solution. Then weigh 49.6g of nickel nitrate, 15.2g of copper nitrate, 2.3g of tin tetrachloride, 2.4g of lanthanum nitrate, and 9.2g of magnesium nitrate and add them to the above solution. Stir to obtain a clear solution.

[0059] (3) The prepared impregnation solution is impregnated onto the carrier in equal volume and left to stand for 2 hours, then dried at 100°C for 10 hours to obtain semi-finished product A1.

[0060] (4) The semi-finished product A was calcined at 550°C for 3 hours. The calcined sample was then reduced in a hydrogen atmosphere (reduction conditions were the same as in Example 1) to obtain catalyst B1.

[0061] The catalyst prepared in Comparative Example 1 was determined by atomic absorption spectrometry, wherein the content of Ni was 10.0%, Cu was 4.0%, Sn was 1.0%, La was 1.0%, and Mg was 1.5%.

[0062] Example 2

[0063] The catalyst preparation process in this embodiment is as follows:

[0064] (1) The pore volume of the No. 2 alumina carrier after calcination at 700℃ for 4 hours was 0.70 mL / g, and the specific surface area was 271 m². 2 / g, weigh out 100g for later use;

[0065] (2) Weigh 74.3g of nickel nitrate, 11.1g of ammonium heptamolybdate, 4.2g of tin tetrachloride, 3.1g of lanthanum nitrate, and 2.5g of magnesium nitrate, add them to 79.7g of deionized water, stir and dissolve; take 22g of ethylenediamine, add it to the clear solution in batches, and stir for 50min to complex.

[0066] (3) The prepared impregnation solution is impregnated onto the carrier in equal volume and left to stand for 1 hour, and then dried at 120°C for 10 hours to obtain semi-finished product E.

[0067] (4) The semi-finished product E was calcined at 600℃ for 3 hours. The calcined sample was then reduced in a hydrogen atmosphere under the following conditions: maintaining a hydrogen space velocity of 1300 h⁻¹. -1 Under a pressure of 0.5 MPa, the temperature was raised to 480℃ and maintained for 30 hours to complete the reduction, yielding semi-finished product F.

[0068] (5) Weigh 7.2g of tetraethyl orthosilicate and dissolve it in 85.4g of anhydrous methanol to obtain a clear solution.

[0069] (6) Immerse an equal volume of tetraethyl orthosilicate alcohol solution onto semi-finished product F, let it stand for 48 hours, and then dry it at 100°C for 5 hours to obtain semi-finished product G.

[0070] (7) Place the semi-finished product G in a hydrothermal reactor and use an acidic aqueous solution with a hydrochloric acid concentration of 0.5wt% for hydrothermal treatment. The feed rate is 50g / h. The hydrothermal treatment is carried out at 120℃ for 1h to obtain the semi-finished product H.

[0071] (8) After drying the semi-finished product H at 80°C for 8 hours, it was calcined at 550°C for 3 hours under a nitrogen atmosphere to obtain the catalyst.

[0072] The catalyst prepared in Example 2 was determined by atomic absorption spectrometry and XRF fluorescence spectrometry, respectively, and the content of Ni was 15.0%, Mo was 6.0%, Sn was 1.9%, La was 1.3%, Mg was 0.4%, and SiO2 was 2.1%.

[0073] Comparative Example 2

[0074] The catalyst preparation process of this comparative example is as follows: the preparation conditions are the same as those in Example 2, except that it is not supported on organosilicon;

[0075] (1) The pore volume of the No. 2 alumina carrier after calcination at 700℃ for 4 hours was 0.70 mL / g, and the specific surface area was 271 m². 2 / g, weigh out 100g for later use;

[0076] (2) Weigh 74.3g of nickel nitrate, 11.1g of ammonium heptamolybdate, 4.2g of tin tetrachloride, 3.1g of lanthanum nitrate, and 2.5g of magnesium nitrate, add them to 79.7g of deionized water, stir and dissolve; take 22g of ethylenediamine, add it to the clear solution in batches, and stir for 50min to complex.

[0077] (3) The prepared impregnation solution is impregnated onto the carrier in equal volume and left to stand for 1 hour, and then dried at 120°C for 10 hours to obtain the semi-finished product E1.

[0078] (4) The semi-finished product E1 was calcined at 600°C for 3 hours. The calcined sample was then reduced in a hydrogen atmosphere (reduction conditions were the same as in Example 2) to obtain catalyst F1.

[0079] The catalyst prepared in Comparative Example 2 was determined by atomic absorption spectrometry, and its content was found to be 15.0% Ni, 6.0% Mo, 1.9% Sn, 1.3% La, and 0.4% Mg.

[0080] Example 3

[0081] The catalyst preparation process in this embodiment is as follows:

[0082] (1) The pore volume of the No. 3 alumina carrier after calcination at 650℃ for 5 hours was 1.38 mL / g, and the specific surface area was 294 m². 2 / g, weigh out 100g for later use;

[0083] (2) Weigh 74.3g of nickel nitrate, 6.3g of silver nitrate, 5.1g of tin tetrachloride, 4.7g of cobalt nitrate, and 4.2g of calcium nitrate, add them to 106g of deionized water, stir and dissolve; take 45.4g of hexamethylenediamine, add it to the clear solution in batches, and stir for 50min to complex.

[0084] (3) The prepared impregnation solution is impregnated onto the carrier in equal volume and left to stand for 2 hours, and then dried at 120°C for 8 hours to obtain semi-finished product I.

[0085] (4) The semi-finished product I was calcined at 450℃ for 6 hours. The calcined sample was then reduced in a hydrogen atmosphere under the following conditions: maintaining a hydrogen space velocity of 800 h⁻¹. -1 Under a pressure of 0.5 MPa, the temperature was raised to 450 °C and maintained for 20 hours to complete the reduction, yielding the semi-finished catalyst J.

[0086] (5) Weigh 9.5g of tetraethyl orthosilicate and dissolve it in 106.6g of anhydrous acetone to obtain a clear solution.

[0087] (6) Immerse an equal volume of tetraethyl orthosilicate alcohol solution onto semi-finished product J, let stand for 10 hours, and then dry at 130°C for 5 hours to obtain semi-finished product K.

[0088] (7) Take the semi-finished product and place it in a hydrothermal reactor. Use an acidic aqueous solution with an acetic acid concentration of 0.8wt% for hydrothermal treatment. The feed rate is 60g / h. Hydrothermal treatment is carried out at 90℃ for 3h to obtain the semi-finished product L.

[0089] (8) The semi-finished product L was dried at 150°C for 3 hours and calcined at 400°C for 7 hours under a nitrogen atmosphere to obtain the catalyst.

[0090] The catalyst prepared in Example 3 was determined by atomic absorption spectrometry and XRF fluorescence spectrometry, respectively, and the content of Ni was 15.0%, Ag was 4.0%, Sn was 2.3%, Co was 1.5%, Ca was 0.7%, and SiO2 was 2.7%.

[0091] Comparative Example 3

[0092] The catalyst preparation process of this comparative example is as follows: the preparation conditions are the same as those in Example 3, except that a complexing agent is not used and no organosilicon is supported;

[0093] (1) The pore volume of the No. 3 alumina carrier after calcination at 650℃ for 5 hours was 1.38 mL / g, and the specific surface area was 294 m². 2 / g, weigh out 100g for later use;

[0094] (2) Weigh 74.3g of nickel nitrate, 6.3g of silver nitrate, 5.1g of tin tetrachloride, 4.7g of cobalt nitrate, and 4.2g of calcium nitrate, add them to 106g of deionized water, stir and dissolve to obtain a clear solution.

[0095] (3) The prepared impregnation solution is impregnated onto the carrier in equal volume and left to stand for 2 hours, and then dried at 120°C for 8 hours to obtain semi-finished product I1.

[0096] (4) The semi-finished product I1 was calcined at 450°C for 6 hours. The calcined sample was then reduced in a hydrogen atmosphere (reduction conditions were the same as in Example 3) to obtain catalyst J1.

[0097] The catalyst prepared in Comparison 3 was determined by atomic absorption spectrometry, and its content was found to be 15.0% Ni, 4.0% Ag, 2.3% Sn, 1.5% Co, and 0.7% Ca.

[0098] Example 4

[0099] The catalyst preparation process in this embodiment is as follows:

[0100] (1) The pore volume of the No. 4 alumina carrier after calcination at 520℃ for 10h was 1.06mL / g, and the specific surface area was 354m². 2 / g, weigh out 100g for later use;

[0101] (2) Weigh 132.8g of nickel nitrate, 42.6g of copper nitrate, 5.5g of tin tetrachloride, 2.4g of lanthanum nitrate, and 9.2g of magnesium nitrate, add them to 71.1g of deionized water, and stir to obtain a clear solution; take 92.5g of hexamethylenediamine, add it to the clear solution in batches, and stir for 90min to complex.

[0102] (3) The prepared impregnation solution is impregnated onto the carrier in equal volume and left to stand for 4 hours, and then dried at 150°C for 4 hours to obtain the semi-finished product M.

[0103] (4) After the semi-finished product M is calcined at 500℃ for 8 hours, the calcined catalyst is reduced in a hydrogen atmosphere under the following conditions: maintaining a hydrogen space velocity of 1000 h⁻¹. -1 Under a pressure of 0.5 MPa, the temperature was raised to 480℃ and maintained for 40 hours to complete the reduction, yielding a semi-finished catalyst N.

[0104] (5) Weigh 3.1g of tetraethyl orthosilicate, dissolve it in 100g of anhydrous ethanol, and stir to obtain a clear solution.

[0105] (6) Immerse an equal volume of tetraethyl orthosilicate alcohol solution onto the semi-finished product N, let it stand for 24 hours, and then dry it at 70°C for 30 hours to obtain the semi-finished product O.

[0106] (7) Take the semi-finished product O and place it in a hydrothermal reactor. Use an acidic aqueous solution with a formic acid concentration of 1.5wt% for hydrothermal treatment. The feed rate is 30g / h. Hydrothermal treatment is carried out at 110℃ for 1.5h to obtain the semi-finished product P.

[0107] (8) The semi-finished product P was dried at 120°C for 6 hours and then calcined at 400°C for 7 hours under a nitrogen atmosphere to obtain the catalyst.

[0108] The catalyst prepared in Example 4 was determined by atomic absorption spectrometry and XRD fluorescence method, respectively, and the content of Ni was 26.8%, Cu was 11.2%, Sn was 2.5%, La was 1.0%, Mg was 1.5%, and SiO2 was 0.9%.

[0109] Comparative Example 4

[0110] The catalyst preparation process in this embodiment is as follows: the preparation conditions are the same as in Example 4, except that a complexing agent is not used, the impregnation process is completed in two steps, and the semi-finished catalyst is impregnated with organosilicon in an oxidized state.

[0111] (1) The pore volume of the No. 4 alumina carrier after calcination at 520℃ for 10h was 1.06mL / g, and the specific surface area was 354m². 2 / g, weigh out 100g for later use;

[0112] (2) Weigh 66.4g of nickel nitrate, 21.3g of copper nitrate, 2.8g of sodium stannate, 1.2g of lanthanum nitrate, and 4.6g of magnesium nitrate, add them to 100.5g of deionized water, and stir to obtain a clear solution;

[0113] (3) The prepared impregnation solution is impregnated onto the carrier in equal volume and left to stand for 4 hours. Then it is dried at 150°C for 4 hours to obtain the semi-finished product M1.

[0114] (4) Repeat steps (2) and (3) to obtain the semi-finished product M11.

[0115] (5) After the semi-finished product M11 is roasted at 500℃ for 8 hours, the semi-finished product N1 is obtained.

[0116] (6) Weigh 3.1g of tetraethyl orthosilicate, dissolve it in 100g of anhydrous ethanol, and stir to obtain a clear solution.

[0117] (7) Immerse an equal volume of tetraethyl orthosilicate alcohol solution onto the semi-finished product N1, let it stand for 24 hours, and then dry it at 70°C for 30 hours to obtain the semi-finished product O1.

[0118] (8) Take the semi-finished product O1 and place it in a hydrothermal reactor. Use an acidic aqueous solution with a formic acid concentration of 1.5wt% for hydrothermal treatment. The feed rate is 30g / h. Perform hydrothermal treatment at 110℃ for 1.5h to obtain the semi-finished product P1.

[0119] (9) After drying the semi-finished product P1 at 120°C for 6 hours, it was calcined at 550°C for 7 hours under a nitrogen atmosphere to obtain the catalyst precursor. After reduction under a hydrogen atmosphere (reduction conditions are the same as in Example 4), the catalyst product was obtained.

[0120] The catalyst prepared in Example 4 was determined by atomic absorption spectrometry and XRF fluorescence spectrometry, respectively, and the content of Ni was 26.8%, Cu was 11.2%, Sn was 2.5%, La was 1.0%, Mg was 1.5%, and SiO2 was 0.7%.

[0121] Example 5

[0122] The catalyst preparation process in this embodiment is as follows:

[0123] (1) The pore volume of the No. 5 alumina carrier after calcination at 450℃ for 12 hours was 0.60 mL / g, and the specific surface area was 228 m². 2 / g, weigh out 100g for later use;

[0124] (2) Weigh 17.2g of ethylenediamine, dissolve it in 73.2g of deionized water, and stir it on a stirrer; weigh 49.6g of nickel nitrate, 15.2g of copper nitrate, and 1.4g of tin tetrachloride, and add them to the ethylenediamine solution to complex for 30min.

[0125] (3) The prepared impregnation solution is impregnated onto the carrier in equal volume, and left to stand for 4 hours. Then it is dried at 80°C for 12 hours to obtain the semi-finished product Q.

[0126] (4) After the semi-finished product Q is calcined at 350℃ for 8 hours, the calcined catalyst is reduced in a hydrogen atmosphere under the following conditions: maintaining a hydrogen space velocity of 300 h⁻¹. -1 After heating to 350℃ under normal pressure and maintaining the temperature for 40 hours, the reduction was completed, and the semi-finished catalyst R was obtained.

[0127] (5) Weigh 18.7g of tetramethoxysilane, dissolve it in 75g of anhydrous acetone, and stir to obtain a clear solution.

[0128] (6) Impregnate the semi-finished product R with an equal volume of acetone solution of tetramethoxysilane, let it stand for 48 hours, and then dry it at 80°C for 24 hours to obtain the semi-finished product S.

[0129] (7) Take the semi-finished product S and place it in a hydrothermal reactor. Use an acidic aqueous solution with a formic acid concentration of 0.2wt% for hydrothermal treatment. The feed rate is 30g / h. Perform hydrothermal treatment at 110℃ for 1.5h to obtain the semi-finished product T.

[0130] (8) The semi-finished product T was dried at 120°C for 6 hours and then calcined at 650°C for 3 hours under a nitrogen atmosphere to obtain the catalyst.

[0131] The catalyst prepared in Example 5 was determined by atomic absorption spectrometry and XRF fluorescence spectrometry, respectively, and the content of Ni was 10.0%, Cu was 4.0%, Sn was 0.64%, and SiO2 was 7.4%.

[0132] Comparative Example 5

[0133] The catalyst preparation process of this comparative example is as follows: the preparation process conditions are the same as those in Example 5, except that Cu and organosilicon are not supported;

[0134] (1) The pore volume of the No. 5 alumina carrier after calcination at 450℃ for 12 hours was 0.60 mL / g, and the specific surface area was 228 m². 2 / g, weigh out 100g for later use;

[0135] (2) Weigh 17.2g of ethylenediamine, dissolve it in 76.5g of deionized water, and stir it on a stirrer; weigh 49.6g of nickel nitrate and 1.4g of tin tetrachloride, and add them to the ethylenediamine solution to complex for 30min.

[0136] (3) The prepared impregnation solution is impregnated onto the carrier in equal volume and left to stand for 4 hours, and then dried at 80°C for 12 hours to obtain the semi-finished product Q1.

[0137] (4) After the semi-finished product Q1 is dried at 120°C for 4 hours, it is calcined at 350°C for 8 hours. The calcined catalyst is then reduced in a hydrogen atmosphere (reduction conditions are the same as in Example 5) to obtain the finished catalyst.

[0138] The catalyst prepared in Comparative Example 5 was determined by atomic absorption spectrometry, and the Ni content was 10.0% and the Sn content was 0.64%.

[0139] Performance of catalysts in maleic anhydride hydrogenation reaction

[0140] Evaluation method:

[0141] The catalyst was loaded into the fixed-bed reactor at a rate of 50 mL, the operating pressure was 2.5 MPa, and the hydrogen-to-anhydride molar ratio was 5–15.

[0142] Catalyst activation conditions: hydrogen flow rate 20 L / h; programmed temperature ramp: room temperature increased to 250 °C at a rate of 30 °C / h, maintained for 10 h; activation completed; cooled to a suitable temperature before feeding. The reactant was γ-butyrolactone solvent with a maleic anhydride concentration of 10 wt%.

[0143] Table 1. Calculation method of evaluation results

[0144]

[0145] The catalyst evaluation results are shown in Table 2.

[0146] Table 2 Catalyst Evaluation Results

[0147]

[0148]

[0149] As can be seen from the comparison of catalyst evaluation results in Table 2:

[0150] Compared with Examples 1 and 2, Comparative Examples 1 and 2, due to the absence of acid-resistant SiO2 coating on the surface of the alumina support, initially showed comparable maleic anhydride conversion and selectivity. However, as the reaction time increased, the framework structure of the alumina support in the comparative examples partially collapsed, resulting in a decrease in both maleic anhydride conversion and selectivity.

[0151] Compared with Example 3, Comparative Example 3 did not use a complexing agent during catalyst impregnation, resulting in poor dispersion of active metals after catalyst reduction. Consequently, the catalyst activity and selectivity were poor. Furthermore, as the reaction time increased, the lack of a protective film on the support surface and the weak acidity in the reaction system caused the collapse of the catalyst framework structure, further reducing the conversion rate of maleic anhydride hydrogenation.

[0152] Compared to Example 4, Comparative Example 4 employed a two-stage impregnation process because the catalyst metal loading was too high to be completed in a single step without a complexing agent. During the first impregnation, the catalyst itself exhibited poor dispersion on the support due to the lack of a complexing agent, resulting in some pore blockage. The second impregnation process further reduced the dispersion of the active metal and the pore structure of the finished catalyst. Furthermore, the organosilicon-supported catalyst precursor was in an oxidized state; the Si-OH formed after organosilicon hydrolysis combined with the metal oxide. Upon reduction, the Si bound to the active metal detached, causing the SiO2 content in the catalyst to decrease compared to the theoretical loading. Therefore, the catalyst exhibited poor activity, selectivity, and stability.

[0153] Compared to Example 5, Comparative Example 5, due to the absence of Cu impregnation and the lack of acid-resistant SiO2 coating on the alumina surface, experienced a faster decrease in maleic anhydride conversion with increasing reaction time. This was primarily due to the loss of active metal Ni caused by acidic substances and the collapse of the carrier framework structure caused by acidic substances. Furthermore, since the system did not contain Cu, its effect on the selectivity of maleic anhydride hydrogenation was relatively small.

[0154] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to prepare succinic anhydride, characterized in that, The catalyst comprises an alumina support, a Ni active component supported on the alumina support, a first auxiliary agent and a second auxiliary agent, and a SiO2 protective film coated on the alumina support; the first auxiliary agent is at least one of Mo, Cu, and Ag, and the second auxiliary agent is at least one of Sn, La, Zn, Co, Mg, and Ca; based on the support mass of 100%, the Ni active component content is 10-28 wt%, the first auxiliary agent content is 3-12 wt%, the second auxiliary agent content is 0.5-5 wt%, and the SiO2 protective film content is 0.5-8 wt%; the catalyst is obtained by impregnating a calcined support loaded with the Ni active component, the first auxiliary agent, and the second auxiliary agent with a complexing impregnation solution containing Ni, the first auxiliary agent, the second auxiliary agent, and a complexing agent; the support loaded with the Ni active component, the first auxiliary agent, and the second auxiliary agent is dried, calcined and reduced, and then impregnated in an impregnation solution containing organosilicon; after drying and hydrothermal reaction, it is dried and calcined again to obtain the catalyst; The hydrothermal reaction is a hydrolysis in an acidic aqueous solution at 90-120°C for 1-3 hours. The acid in the acidic aqueous solution is at least one of hydrochloric acid, formic acid, and acetic acid, and the acid concentration is 0.1-2 wt%.

2. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The alumina carrier has a specific surface area of ​​200~400 m². 2 / g, with a pore volume of 0.6~1.4mL / g.

3. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The alumina carrier has a specific surface area of ​​280~350m². 2 / g, with a pore volume of 0.8~1.2mL / g.

4. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The complexing agent is at least one of ethylenediaminetetraacetic acid (EDTA), ethylenediamine (EDA), propylenediamine (PDA), butanediamine (BDA), hexamethylenediamine (HDA), citrate (CA), nitric acid triacetic acid (NTA), cyclohexanediaminetetraacetic acid (CyDTA), and ethylene glycol (EG).

5. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The impregnation time of the alumina carrier in the complexing impregnation solution is 1~4h, the drying temperature is 80~150℃, the drying time is 4~12h, the calcination temperature is 350~600℃, and the calcination time is 3~8h.

6. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The reduction temperature is 350~480℃, the reduction pressure is atmospheric pressure to 0.5MPa, and the reducing gas space velocity is 300~1500h. -1 The restoration time is 5 to 40 hours.

7. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The organosilicon is at least one of tetraethyl orthosilicate, tetramethoxysilane, tetraethoxysilane, and methyltrioxysilane.

8. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The organosilicon is tetraethyl orthosilicate and / or tetramethoxysilane.

9. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The organosilicon-containing impregnation solution is prepared by dissolving the organosilicon in an organic solvent, wherein the organic solvent is at least one selected from methanol, ethanol, propanol, butanol, and acetone.

10. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 9, characterized in that, The organic solvent is ethanol and / or methanol.

11. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The impregnation time in the silicone-containing impregnation solution is 10-50 hours, and the drying conditions after impregnation are 70-130℃ for 5-30 hours.

12. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The acid concentration of the acidic aqueous solution in the hydrothermal reaction is 0.3~1.0 wt%.

13. The catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to succinic anhydride according to claim 1, characterized in that, The drying conditions after the hydrothermal reaction are 80~150℃ for 3~8h, and the calcination conditions are 400~700℃ for 3~7h under an inert atmosphere.

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