A method for preparing a Cu catalyst and its application in the production of γ-butyrolactone from succinic anhydride.

Abstract

This invention discloses a method for preparing a Cu catalyst and its application in the production of γ-butyrolactone from succinic anhydride, specifically a catalyst for the gas-phase hydrogenation of succinic anhydride to prepare γ-butyrolactone. The preparation method of the Cu-Ce / Al₂O₃ catalyst includes: using Cu and Ce nitrates as precursors, and under the action of the precipitant CH₃COONH₄, using a deposition-precipitation method to precipitate and anchor the active metal Cu and the electronic auxiliary agent Ce in a support, followed by drying, calcination, and reduction treatment to obtain the catalyst. The catalyst of this invention consists of the active center Cu, the auxiliary agent Ce, and the support Al₂O₃, and does not contain toxic components such as Cr and Zr, making it a green catalyst. Furthermore, the catalyst does not contain noble metal components such as Pt, Pd, and Ru. In a fixed-bed reactor, the conversion rate of succinic anhydride is greater than 99%, and the selectivity of γ-butyrolactone is greater than 99%. Due to the strong anchoring effect of the precipitant on the active components of the catalyst, the catalyst cycle stability for this reaction reaches more than 1000 hours without deactivation.

Description

Technical Field

[0001] This invention belongs to the field of catalysis, specifically relating to a method for preparing Cu nanocatalysts and their application in the hydrogenation of succinic anhydride to produce γ-butyrolactone. Background Technology

[0002] Gamma-butyrolactone (GBL) is an important fine chemical intermediate that can participate in a variety of chemical reactions due to its unique physicochemical properties. Furthermore, GBL has very high solubility and is widely used in industrial production as a powerful and environmentally friendly solvent. In the petrochemical industry, GBL can be used as a plasticizer, antioxidant, dispersant, coagulant, absorbent, and extractant. In the pharmaceutical industry, GBL can be used to produce anesthetics, X-ray contrast agents, sedatives, and pharmaceutical intermediates such as ciprofloxacin, interferon, and vitamin B1. In the agricultural industry, GBL can be used as an intermediate in the production of plant growth regulators, herbicides, and pesticides. In the textile industry, GBL and its downstream products can be used to produce fabric dyes, textile solvents, coagulants, and plasticizers. Additionally, in the production of lithium batteries, GBL can serve as a special non-aqueous solvent for lithium ions.

[0003] There are various synthetic routes for GBL, but the production processes generally suffer from problems such as complexity, high equipment requirements, harsh reaction conditions, and high production costs. The 1,4-butanediol dehydrogenation method is currently the main process for producing γ-butyrolactone both domestically and internationally. This process uses 1,4-butanediol (BDO) as a raw material to directly generate γ-butyrolactone under the action of a catalyst, while simultaneously producing hydrogen as a byproduct. Previously, 1,4-butanediol was mainly produced via the Reppe process, but now the maleic anhydride hydrogenation process is increasingly adopted, producing 1,4-butanediol via intermediates such as succinic anhydride, γ-butyrolactone, or tetrahydrofuran. Therefore, using 1,4-butanediol for reverse dehydrogenation to prepare γ-butyrolactone is clearly unreasonable. Furthermore, due to the rapid development of the biodegradable materials field, the price of BDO has increased, significantly reducing the economic viability of producing GBL via the 1,4-butanediol dehydrogenation method.

[0004] In recent years, with the large-scale industrial production of maleic anhydride (MA) through the oxidation of n-butane, and the adoption of large-scale fluidized bed and moving bed oxidation technologies, the production cost of maleic anhydride has been significantly reduced, making the hydrogenation of maleic anhydride to GBL process highly competitive. Currently, my country has a severe overcapacity of maleic anhydride, and its price is low and its sources are abundant. Therefore, the cost of succinic anhydride (SAA) feedstock prepared after hydrogenation is also low, significantly lower than the cost of feedstock for the hydrogenation of succinic anhydride to γ-butyrolactone. This makes the selective hydrogenation of maleic anhydride to γ-butyrolactone a competitive process route. Therefore, this direction has good social value and economic benefits. This project adopts the selective hydrogenation route of SAA to produce GBL. Using MA and H2 as feedstocks, the reaction conditions are mild, the product selectivity is high, it is suitable for fixed-bed reaction processes, and large-scale continuous production is possible. Meanwhile, since the butane oxidation to MA technology is mature, the domestic maleic anhydride market is in a state of oversupply, the price of maleic anhydride is low, and the raw material sources are wide and cheap, which can further reduce the raw material cost of MA hydrogenation to GBL, and significantly enhance the technical and cost advantages of MA to GBL via SA hydrogenation.

[0005] In existing technologies, γ-ray dimethyl sulfadiazine is synthesized by hydrogenation from succinic anhydride. Butyrolactone catalysts have limited applications in chemical production. Generally, the surface electronic state and geometry of a catalyst are closely related to its catalytic activity. For example, the exposed metal interface, lattice distortion, surface charge of the active metal, and the strength of the interaction between the active metal and the support all significantly influence the catalyst's performance. Therefore, controlling the surface structure of the catalyst to manage reactant adsorption and activation is an effective way to improve its catalytic activity. Furthermore, according to numerous studies, most catalytic reactions involve multiple steps and the roles of various catalytic active sites. Therefore, the role of active sites in catalytic reactions cannot be ignored. For catalysts, controlling the degree of hydrogenation of succinic anhydride, reducing the formation of tetrahydrofuran, and lowering reaction conditions all depend on the specific properties of the active metal and the interaction with the support. Summary of the Invention

[0006] The purpose of this invention is to provide a copper catalyst, its preparation method, and its application. Specifically, it aims to provide a highly efficient catalyst for the preparation of γ-butyrolactone from succinic anhydride, improving the reaction yield and stability. This enables the catalyst to produce high-value-added products, enhancing product competitiveness and overall economic efficiency.

[0007] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: A highly efficient Cu catalyst for the preparation of γ-butyrolactone from succinic anhydride comprises a hydrogenation active site metal, an acidic site, an activity regulating agent, and a support.

[0008] The hydrogenation active sites are provided by a transition metal, the acidic sites are provided by a support metal oxide, and the activity regulating agent is a metal oxide. That is, the catalyst comprises a transition metal Cu, a solid acid metal oxide, an activity regulating agent, and a support.

[0009] Preferably, the active metal Cu particles account for 10 wt% to 40 wt% of the catalyst.

[0010] Preferably, the copper source for the active copper particles includes Cu(NO3)2·3H2O and CuCl2.

[0011] Preferably, the precipitant prepared by the catalyst is CH3COONH4 and Na2CO3.

[0012] Preferably, the aluminum source providing the alumina support includes one or more of aluminum nitrate, aluminum sulfate, and aluminum chloride.

[0013] The present invention also provides a method for preparing the catalyst for the preparation of γ-butyrolactone from succinic anhydride, comprising the following steps: (1) mixing Cu source, Ce source, Al source and solvent, and reacting the resulting mixed solution under microwave heating to obtain a mixed solution; (2) The solution obtained in step (1) is subjected to precipitation, drying, calcination and reduction reaction in sequence to obtain the final catalyst.

[0014] Preferably, the microwave heating temperature in step (1) is 40-90°C and the microwave heating time is 1-6 h.

[0015] Preferably, the calcination temperature in step (2) is 350-600℃ and the calcination time is 4-8h.

[0016] Preferably, the reduction reaction in step (2) is carried out in a tubular furnace and a fixed-bed reactor under a hydrogen atmosphere.

[0017] Preferably, the temperature of the reduction reaction in step (2) is 200-500°C and the time of the reduction reaction is 2-8 hours.

[0018] This invention provides the application of the copper catalyst described in the above technical solution or the catalyst prepared using the above technical solution in the catalytic reaction of succinic acid to γ-butyrolactone.

[0019] This invention provides a Cu catalyst comprising active copper particles and a support. The active metal particles with a particle size of less than 10 nm account for 40% to 90% of the total number of active metal particles. In the catalyst provided by this invention, the vast majority of the active metal particles have a particle size of less than 10 nm, exhibiting high metal dispersion and exposing more active sites, thus improving the catalytic efficiency of the catalyst. The results of the embodiments of this application show that using the Cu / Al₂O₃ catalyst provided by this invention to catalyze the preparation of γ-butyrolactone from succinic anhydride achieves a succinic anhydride conversion rate of up to 99% and a γ-butyrolactone selectivity of up to 99%, without generating common byproducts such as tetrahydrofuran, 1,4-butanediol, and propionic acid. Furthermore, it exhibits high catalytic stability, maintaining its excellent catalytic performance even after 1000 h of reaction, making it suitable for industrial production and application. Detailed Implementation

[0020] The embodiments of the present invention will be described in detail below with reference to specific examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0021] Unless otherwise specified, any ratio of additives may be used in this invention.

[0022] The present invention also provides a method for preparing the catalyst for the preparation of γ-butyrolactone from succinic anhydride, comprising the following steps: (1) mixing Cu source, Ce source, Al source and solvent, and reacting the resulting mixed solution under microwave heating to obtain a mixed solution; (2) The solution obtained in step (1) is subjected to precipitation, drying, calcination and reduction reaction in sequence to obtain the final catalyst.

[0023] This invention involves mixing a copper source, a cerium source, an aluminum source, and a solvent, and reacting them under microwave heating to obtain a mixed solution. In this invention, the solvent preferably includes an alcohol and water; the alcohol preferably includes one or more of methanol, ethanol, and propanol. To ensure sufficient mixing of the copper, cerium, and aluminum sources in the solvent, this invention preferably first provides solutions of the copper and cerium sources, and then mixes these solutions with an aluminum source solution to obtain the mixed solution.

[0024] In this invention, the copper-cerium solution is preferably a copper-cerium source ethanol solution. The molar concentration of the copper-cerium source ethanol solution is preferably 0.01–0.2 mol / L, more preferably 0.056–0.1 mol / L, and most preferably 0.1–0.15 mol / L.

[0025] In this invention, the aluminum source solution is preferably an aluminum source ethanol solution. In this invention, the molar ratio of the aluminum source solution... The concentration of mol / L is preferably 0.04–3.0 mol / L, more preferably 0.1–2 mol / L, and most preferably 0.2–1.0 mol / L.

[0026] After obtaining solutions of the two metals, the present invention mixes the copper-cerium source solution and the aluminum source solution. The present invention does not impose any special limitations on the mixing; any mixing technique well-known to those skilled in the art can be used. The present invention preferably mixes the different solutions at room temperature by stirring. In the present invention, the stirring speed is preferably 100–1000 rpm, more preferably 400–800 rpm; the stirring time is preferably 15–45 min. After obtaining the mixed solution, the present invention reacts the mixed solution under microwave heating to make it uniformly mixed. In the mixed solution, a precipitant is used to deposit the metal solution and the carrier into a solid. The present invention uses a weakly acidic or weakly alkaline agent to precipitate the mixed solution. This operation is performed under microwave heating. Finally, all the metal nitrate solutions are deposited into a completely anchored solid precipitate. In the present invention, the concentration of the precipitant is preferably 0.5–5 mol / L, more preferably 0.8–4 mol / L, and most preferably 1–2 mol / L.

[0027] This invention does not impose any special restrictions on the equipment used for microwave heating; any equipment well-known to those skilled in the art for microwave heating can be used. Preferably, a microwave reactor is used for the microwave heating. In this invention, the microwave heating power is preferably 200–1000 W, more preferably 400–800 W; the microwave heating time is preferably 5–120 min, more preferably 20–100 min, and most preferably 30–60 min; the microwave heating temperature is preferably 40–100 °C, more preferably 50–80 °C, and most preferably 60–70 °C.

[0028] After obtaining the mixed solution, the present invention subjectes the solution to drying, calcination, and reduction reactions to obtain the catalyst. The present invention does not impose any special limitations on the drying method; any drying technique well-known to those skilled in the art can be used. In the present invention, the drying is preferably performed under normal pressure. The present invention does not impose any special limitations on the equipment used for drying; any drying equipment well-known to those skilled in the art can be used. In the present invention, the vacuum drying temperature is preferably 60–150°C, more preferably 70–120°C, and most preferably 80–100°C; the vacuum drying time is preferably 4–24 hours, more preferably 6–15 hours, and most preferably 8–12 hours.

[0029] After drying, the dried material is calcined to obtain a calcined product. The present invention does not have any special limitations on the equipment used for calcination; any calcination equipment well known to those skilled in the art can be used. Preferably, a muffle furnace is used to calcine the dried material. In the present invention, the calcination temperature is preferably 250–700°C, more preferably 350–600°C, and most preferably 4000–550°C; the calcination time is preferably 2–8 hours, more preferably 3–6 hours.

[0030] After obtaining the calcined product, the present invention subjectes the calcined product to a metal reduction reaction to obtain the final catalyst. Preferably, the calcined product is ground before the reduction reaction. In the present invention, the particle size of the ground material is preferably 40-60 mesh.

[0031] In this invention, the reduction reaction is preferably carried out under a high-purity hydrogen atmosphere. This invention does not impose any particular limitations on the reactor used for the reduction reaction; any reactor well-known to those skilled in the art for carrying out reduction reactions can be used. This invention preferably uses a tubular furnace to perform the reduction reaction on the ground material. In this invention, the flow rate of the mixed gas introduced into the tubular furnace is preferably 10–100 mL / min, more preferably 20–80 mL / min, and most preferably 30–60 mL / min.

[0032] In this invention, the temperature of the reduction reaction is preferably 150-500°C, more preferably 200-400°C, and most preferably 220-280°C; the time of the reduction reaction is preferably 1-12 hours, more preferably 3-8 hours.

[0033] After the reduction reaction is completed, the catalyst obtained is preferably sealed and stored at 0–20°C.

[0034] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0035] Example 1 This embodiment relates to a method for preparing a Cu catalyst for the hydrogenation of succinic anhydride to γ-butyrolactone, which includes the following steps: (1) Take a 200mL beaker and mix 4.726 g Cu(NO3)2·3H2O, 1.26 g Ce(NO3)2·6H2O with 100mL ethanol to obtain a nitrate solution; mix 14.717 g Al(NO3)3·9H2O with 100mL ethanol to prepare an aluminum nitrate solution. (2) Mix the nitrate solution and aluminum nitrate solution from step (1) evenly and stir at 800 rpm for 15 min at room temperature. Place the resulting mixed solution in a microwave reactor and microwave heat it for 15 min with stirring at 800 rpm to obtain a completely dissolved mixed solution; wherein, the microwave heating power is 300W and the microwave heating temperature is 70℃.

[0036] (3) Weigh 16.612 g of CH3COONH4 and dissolve it in 50 mL of ethanol solution. Stir and sonicate to ensure complete dissolution, and then microwave heat. Use a dropper to slowly add the CH3COONH4 solution to a mixed solution of copper nitrate and aluminum nitrate while stirring. At this time, a precipitate will appear in the solution.

[0037] (4) All CH3COONH4 solution was added dropwise to the mixed solution, which was now in a colloidal state. The solution was transferred to a centrifuge tube, and the ethanol solution was separated from the precipitate using a centrifuge. The mixture was then washed with ethanol and centrifuged again. The centrifugation speed was 3000 rpm, and each centrifugation time was 5 min. This process was repeated three times to obtain a copper-cerium-aluminum mixture precipitated with CH3COONH4.

[0038] (5) The copper-cerium-aluminum mixture obtained in step (4) was dried in an oven at 120°C for 12 h. After drying, it was ground into powder in a mortar. Then, it was transferred to a muffle furnace and calcined at 450°C for 4 h with a programmed temperature increase of 5°C / min. The material was then pressed into tablets to 40-60 mesh. The pressed material was placed in a tube furnace and reduced with metallic Cu at 350°C under high-purity hydrogen conditions for 6 h. The flow rate of the mixed gas introduced into the tube furnace was 10 mL / min. The final Cu-Ce / Al2O3 catalyst was obtained and sealed and stored at 20°C.

[0039] Example 2 Weigh 40 g of succinic anhydride and dissolve it in 160 g of γ-butyrolactone solution to prepare a 20% succinic anhydride solution. This solution is used for the hydrogenation reaction of succinic anhydride.

[0040] 2 g of the Cu-Ce / Al2O3 catalyst prepared in Example 1 and succinic anhydride solution were reacted in a fixed bed to obtain γ-butyrolactone.

[0041] The hydrogenation activity was tested using a fixed-bed reactor. The experimental reactor consisted of a reaction tube with an inner diameter of 4 mm. Accurately weighed catalyst was pre-placed in the isothermal zone of the reactor and supported by silica wool. The catalyst bed temperature was measured using a type K thermocouple. The feed flow rate was maintained at 20-100 mL / min, with a maximum reaction temperature of 300℃ and a minimum temperature of 150℃. Catalyst activity analysis experiments were conducted at both the high-temperature and low-temperature ends. The high-temperature end test involved introducing hydrogen gas at a rate of 50 mL / min, and then gradually increasing the reactor temperature from room temperature to the maximum reaction temperature at a rate of 5℃ / min.

[0042] The composition of the reactants and products for the hydrogenation of succinic anhydride to γ-butyrolactone was determined using an Agilent GC-7890 gas chromatograph with an FID detector and a DB-624 (30m × 320μm × 1.8μm) capillary column. The chromatographic conditions were as follows: helium as the carrier gas at a flow rate of 30 mL / min; air as the combustion gas at a flow rate of 360 mL / min; and hydrogen as the combustion gas at a flow rate of 30 mL / min. The detector temperature and vaporization chamber temperature were both 250 °C. The column temperature was programmed to increase from 120 to 230 °C, initially held at 120 °C for 1 min, then increased at a rate of 8 °C / min to 230 °C and held at 230 °C for 1 min. The mass percentage of each component was calculated using the corrected area normalization method.

[0043] The catalyst was placed in a fixed-bed reactor at a liquid hourly space velocity of 0.2 h⁻¹. -1 The pressure was 3.0 MPa, and the temperature was increased to 220°C at a rate of 5°C / min. A 20% succinic anhydride / γ-butyrolactone solution was used as the reactant, and the hydrogenation reaction was carried out at a hydrogen-to-anhydride ratio of 50:1. The reaction results are listed in Table 1.

[0044] Example 3 (1) Take a 200mL beaker and mix 4.726 g Cu(NO3)2·3H2O with 100 mL ethanol to obtain a copper nitrate solution; at the same time, weigh 3.75 g of commercial γ-Al2O3 support and add it to the solution. (2) The copper nitrate and carrier mixture solution in step (1) was microwave heated for 15 min under stirring at 800 rpm to obtain a completely dissolved mixed solution; wherein the microwave heating power was 300W and the microwave heating temperature was 70℃.

[0045] (3) Weigh 16.612 g of CH3COONH4 and dissolve it in 50 mL of ethanol solution. Stir and sonicate to ensure complete dissolution, and then microwave heat. Use a dropper to slowly add the CH3COONH4 solution to a mixed solution of copper nitrate and aluminum nitrate while stirring. At this time, a precipitate will appear in the solution.

[0046] (4) All CH3COONH4 solution was added dropwise to the mixed solution, which was now in a colloidal state. The solution was transferred to a centrifuge tube, and the ethanol solution was separated from the precipitate using a centrifuge. The mixture was then washed with ethanol and centrifuged again. The centrifugation speed was 3000 rpm, and each centrifugation time was 5 min. This process was repeated 3 times to obtain a copper-aluminum mixture precipitated from CH3COONH4.

[0047] (5) The copper-aluminum mixture obtained in step (4) was dried in an oven at 120°C for 12 h. After drying, it was ground into powder in a mortar. Then, it was transferred to a muffle furnace and calcined at 450°C for 4 h with a programmed temperature increase of 5°C / min. The material was then pressed into tablets to 40-60 mesh. The pressed material was placed in a tube furnace and reduced with metallic Cu at 350°C under high-purity hydrogen conditions for 6 h. The flow rate of the mixed gas introduced into the tube furnace was 10 mL / min. The final Cu / Al2O3 catalyst was obtained and sealed and stored at 20°C.

[0048] Example 4 The catalyst prepared in Example 3 was subjected to a liquid hourly space velocity (LHSV) of 0.2 h⁻¹ in a fixed-bed reactor. -1 The pressure was 3.0 MPa, and the temperature was increased to 220°C at a rate of 5°C / min. A 20% succinic anhydride / γ-butyrolactone solution was used as the reactant, and the hydrogenation reaction was carried out at a hydrogen-to-anhydride ratio of 50:1. The reaction results are listed in Table 1.

[0049] Example 5 (1) Take a 200mL beaker and mix 4.726 g Cu(NO3)2·3H2O, 1.26 g Ce(NO3)2·6H2O with 100mL ethanol to obtain a nitrate solution; mix 14.717 g Al(NO3)3·9H2O with 100mL ethanol to prepare an aluminum nitrate solution. (2) Mix the nitrate solution and aluminum nitrate solution from step (1) evenly and stir at 800 rpm for 15 min at room temperature. Place the resulting mixed solution in a microwave reactor and microwave heat it for 15 min with stirring at 800 rpm to obtain a completely dissolved mixed solution; wherein the microwave heating power is 300W and the microwave heating temperature is 70℃.

[0050] (3) Weigh 12.376 g of Na2CO3 and dissolve it in 50 mL of ethanol solution. Stir and sonicate to ensure complete dissolution. Use a dropper to slowly add the sodium carbonate solution to the nitrate solution. At this time, a precipitate of strong copper oxide will appear in the solution.

[0051] (4) Add all sodium carbonate solution dropwise to the mixed solution. Transfer it to a centrifuge tube and separate the ethanol solution from the precipitate using a centrifuge. Then, continue washing with ethanol and centrifuging. The centrifugation speed is 3000 rpm, and the centrifugation time is 5 min each time. Repeat 3 times to wash away Na ions and successfully obtain a copper-aluminum-cerium mixture of sodium carbonate precipitate.

[0052] (5) The copper-aluminum-cerium mixture obtained in step (4) was dried in an oven at 120°C for 12 h. After drying, it was ground into powder in a mortar. Then, it was transferred to a muffle furnace and calcined at 450°C for 4 h with a programmed temperature increase of 5°C / min. The material was then pressed into tablets to 40-60 mesh. The pressed material was placed in a tube furnace and reduced with metallic Cu at 350°C under high-purity hydrogen conditions for 6 h. The flow rate of the mixed gas introduced into the tube furnace was 10 mL / min. The final Cu-Ce / Al2O3 catalyst was obtained and sealed and stored at 20°C.

[0053] Example 6 The catalyst prepared in Example 5 was subjected to a liquid hourly space velocity (LHSV) of 0.2 h⁻¹ in a fixed-bed reactor. -1 The pressure was 3.0 MPa, and the temperature was increased to 220°C at a rate of 5°C / min. A 20% succinic anhydride / γ-butyrolactone solution was used as the reactant, and the hydrogenation reaction was carried out at a hydrogen-to-anhydride ratio of 50:1. The reaction results are listed in Table 1.

[0054] Comparative Example 1 (1) Add Cu(NO3)2·3H2O and commercial γ-Al2O3 support to deionized water and stir. (2) Weigh 16.612 g of oxalic acid dihydrate and dissolve it in 50 mL of aqueous solution. Stir and sonicate to ensure complete dissolution. Add the precipitant dropwise into the solution using a dropper. At this point, a precipitate of strong copper oxide will appear in the solution.

[0055] (3) Transfer it to a centrifuge tube and use a centrifuge to separate the solution from the precipitate.

[0056] (4) The copper-aluminum mixture obtained in step (3) was dried in an oven at 120°C for 12 h. After drying, it was ground into powder in a mortar. Then, it was transferred to a muffle furnace and calcined at 450°C for 4 h with a programmed temperature increase of 5°C / min. The material was then pressed into tablets to 40-60 mesh. The pressed material was placed in a tube furnace and reduced with metallic Cu at 350°C under high-purity hydrogen conditions for 6 h. The flow rate of the mixed gas introduced into the tube furnace was 10 mL / min. The final Cu / Al2O3 catalyst was obtained and sealed and stored at 20°C.

[0057] Comparative Example 2 The catalyst prepared in Comparative Example 1 was subjected to a liquid hourly space velocity (LHSV) of 0.2 h⁻¹ in a fixed-bed reactor. -1 The pressure was 3.0 MPa, and the temperature was increased to 220°C at a rate of 5°C / min. A 20% succinic anhydride / γ-butyrolactone solution was used as the reactant, and the hydrogenation reaction was carried out at a hydrogen-to-anhydride ratio of 50:1. The reaction results are listed in Table 1.

[0058] Comparative Example 3 (1) Add Cu(NO3)2·3H2O and commercial γ-Al2O3 support to deionized water and stir. (2) Weigh 12.376 g of Na2CO3 and dissolve it in 50 mL of aqueous solution. Stir and sonicate to ensure complete dissolution. Add the precipitant dropwise into the solution using a dropper. At this point, a precipitate of strong copper oxide will appear in the solution.

[0059] (3) Transfer it to a centrifuge tube and use a centrifuge to separate the solution from the precipitate.

[0060] (4) The copper-aluminum mixture obtained in step (3) was dried in an oven at 120°C for 12 h. Then it was transferred to a muffle furnace and calcined at 450°C for 4 h with a programmed temperature increase of 5°C / min. The material was then pressed into tablets to 40-60 mesh. The tableted material was placed in a tube furnace and subjected to reduction of metallic Cu at 350°C under high-purity hydrogen conditions for 6 h. The flow rate of the mixed gas introduced into the tube furnace was 10 mL / min. The final catalyst was sealed and stored at 20°C.

[0061] Comparative Example 4 The catalyst prepared in Comparative Example 3 was subjected to a liquid hourly space velocity (LHSV) of 0.2 h⁻¹ in a fixed-bed reactor. -1 The pressure was 3.0 MPa, and the temperature was increased to 220°C at a rate of 5°C / min. A 20% succinic anhydride / γ-butyrolactone solution was used as the reactant, and the hydrogenation reaction was carried out at a hydrogen-to-anhydride ratio of 50:1. The reaction results are listed in Table 1.

[0062] Table 1. Catalysts for the preparation of γ-rays by hydrogenation of succinic anhydride Activity data for butyrolactone.

[0063]

[0064] As shown in Table 1, in the catalyst of Example 2, due to the efficient anchoring effect of the precipitant CH3COONH4 and the dispersion of Ce, the conversion rates of succinic anhydride and γ-butyrolactone both reached 99%, and no byproducts such as tetrahydrofuran, 1,4-butanediol, n-butanol, and propionic acid were generated. In Comparative Examples 2 and 4, CH3COONH4 was not used as a precipitant; instead, conventional Na2CO3 and oxalic acid were used for precipitation, resulting in significantly reduced conversion rates and selectivity. Furthermore, using commercial alumina as the Al source was not conducive to the loading of the active components in the catalyst, leading to low catalytic performance.

[0065] Table 2. Preparation of γ-rays by hydrogenation of succinic anhydride using various catalysts The reaction stability of butyrolactone.

[0066]

[0067] As shown in Table 2, the catalyst in Example 2 remained undeactivated after 1000 h of reaction, indicating its strong stability and suitability for industrial production. This efficiency is attributed to the dispersing effect of the promoter Ce on the active component, exposing more active sites for Cu. Furthermore, CH3COONH4, with its weak acid and weak base properties, exhibits superior binding and stabilizing properties for metal nanoparticles compared to common precipitants such as Na2CO3 and oxalic acid due to its strong adsorption and metal anchoring deposition characteristics. These excellent properties result in a catalyst with uniquely high conversion rate, selectivity, and stability.

[0068] Table 3 shows the Cu content results of each catalyst in the ICP test after 1000 h of reaction:

[0069] To verify the reasons for the differences in catalyst stability, ICP tests were performed on each catalyst after 1000 h of reaction, and the results are shown in Table 3. In Example 2, the catalyst remained undeactivated after 1000 h of reaction, and the Cu content was almost unchanged from before the reaction. This indicates that the CH3COONH4 precipitant effectively deposited Cu in the support and deeply anchored it, resulting in strong catalyst stability. In contrast, the performance of the other comparative catalysts decreased significantly, attributed to the lack of Ce dispersion and CH3COONH4 precipitation, leading to catalyst structural instability and phenomena such as coking and metal detachment.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. In addition, those skilled in the art can understand that although some embodiments here include certain features included in other embodiments but not other features, the combination of features of different embodiments means that they are within the scope of the present invention and form different embodiments. For example, in the above claims, any one of the claimed embodiments can be used in any combination. The information disclosed in this background section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form implying that the information constitutes prior art known to those skilled in the art.

Claims

1. The application of Cu catalyst in the catalytic hydrogenation of succinic anhydride to prepare γ-butyrolactone, characterized in that, The preparation method of Cu catalyst includes the following steps: (1) Mix copper source, cerium source, aluminum carrier source and solvent, and react the resulting mixed solution under microwave heating to fully dissolve it; the microwave heating temperature is 40~90℃ and the heating time is 1~6h; The copper sources are Cu(NO3)2·3H2O and CuCl2; The aluminum source for the carrier is one or more of aluminum nitrate, aluminum sulfate, and aluminum chloride; (2) Add CH3COONH4 precipitant to the solution obtained in step (1) until a certain pH value is reached, and age it. Then, dry, calcine and reduce the reaction in sequence to obtain the catalyst. The calcination temperature is 350~600℃ and the calcination time is 4~8h. The reduction reaction temperature is 200~500℃ and the reduction reaction time is 2~8h.

2. The application according to claim 1, characterized in that, The reduction reaction in step (2) is carried out in a tubular furnace or fixed bed under a hydrogen atmosphere.

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