A dimethyl maleate hydrogenation catalyst, a preparation method and application thereof

Abstract

The application discloses a dimethyl maleate hydrogenation catalyst and a preparation method and application thereof. The catalyst comprises CuO, Al2O3 and Mn oxide; the specific surface area of the catalyst is 40-70 m 2 / g; the catalyst is subjected to H2-N2O titration test, and the dispersion degree of metal Cu is 42-70%. The catalyst is used for hydrogenation of dimethyl maleate to prepare 1,4-butanediol, gamma-butyrolactone and tetrahydrofuran in combination, and has high conversion rate and target product selectivity.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a hydrogenation catalyst for dimethyl maleate, its preparation method, and its application. Background Technology

[0002] 1,4-Butanediol (BDO) is an important raw material for organic and fine chemicals, widely used in pharmaceuticals, daily chemicals, textiles, and papermaking. Industrially, the main processes for producing 1,4-butanediol include the acetylacetic aldehyde method, the maleic anhydride hydrogenation method (direct hydrogenation of maleic anhydride, hydrogenation via esterification of maleic anhydride), the butadiene method, and the propylene oxide method. Among these, the maleic anhydride esterification hydrogenation method is widely recognized as the most technically and economically efficient process, producing high-value-added byproducts such as γ-butyrolactone (GBL) and tetrahydrofuran (THF) during BDO production, and represents the main development trend in BDO production processes.

[0003] The process for producing BDO by hydrogenation of maleic anhydride mainly includes three units: esterification of maleic anhydride to synthesize dimethyl maleate, hydrogenation of dimethyl maleate to prepare 1,4-butanediol, and product distillation. Among these, the development of catalysts and processes for hydrogenation of dimethyl maleate to BDO is the core unit, and this process currently mainly uses copper-based catalysts.

[0004] CN117599801A discloses a method for preparing a catalyst for the hydrogenation of dimethyl maleate to 1,4-butanediol. The method includes using deionized water as a base solution, sequentially precipitating an auxiliary metal, a support, and an active metal. After precipitation, the material is aged, washed, dried, calcined, and shaped into a Raschig ring to obtain the catalyst for the hydrogenation of dimethyl maleate to 1,4-butanediol. The auxiliary metal is Mn, Zn, Mg, or Zr, and the active metal is Cu. The selectivity can reach up to 95.8%.

[0005] CN113731442B discloses a catalyst for the hydrogenation reaction of dimethyl maleate, its preparation method, and its application. The catalyst is prepared first by a co-precipitation method, followed by the addition of a catalyst promoter. The molar percentages of each element are: Cu 30–40%, Mn 20–30%, Al 10–20%, Zn 10–20%, Ag 0–5%, and Ru 0–5%. The total selectivity of BDO and γ-butyrolactone during the reaction can reach 93%.

[0006] Currently, some progress has been made in the development of Cu-based catalysts for the hydrogenation of dimethyl maleate to 1,4-butanediol. However, when using a stepwise precipitation method to precipitate the promoter, support, and active metal separately, multiple steps such as filtration, washing, and drying are required. This weakens the interaction between the active metal and the support promoter, leading to uneven composition of the catalyst precursor or even agglomeration. In addition, since Cu has a low sintering temperature, the hydrogenation reaction is accompanied by an exothermic process. When the reaction activity is too high, Cu grains will spontaneously grow, reducing the metal dispersion and thus causing catalyst deactivation. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a hydrogenation catalyst for dimethyl maleate, its preparation method, and its application. The catalyst obtained by this invention is used for the hydrogenation of dimethyl maleate to 1,4-butanediol, with co-production of γ-butyrolactone and tetrahydrofuran, exhibiting high conversion rate and selectivity for the target products.

[0008] The first aspect of this invention provides a hydrogenation catalyst for dimethyl maleate, the catalyst comprising oxides of CuO, Al₂O₃, and Mn; the specific surface area of ​​the catalyst is 40–70 m². 2 / g, preferably 45-65m 2 / g; the catalyst was tested by H2-N2O titration, and the dispersion of metallic Cu was 42% to 70%.

[0009] Furthermore, the catalyst is tested by H2-N2O titration, and the dispersion of metallic Cu is 42% to 70%, such as, but not limited to, 42%, 45%, 50%, 52%, 55%, 58%, 60%, 65%, 70%, etc., and any value within the range formed by any two of these values.

[0010] Furthermore, based on the weight of the catalyst, the weight contents of each component are as follows: copper content (calculated as CuO) is 40% to 70%, aluminum content (calculated as Al2O3) is 20% to 40%, and manganese content (calculated as MnO) is 5% to 15%.

[0011] Furthermore, the catalyst also contains a forming aid, such as graphite, which accounts for less than 5% by weight in the catalyst, and more specifically 0.1% to 5%.

[0012] Furthermore, the catalyst has a pore volume of 0.15–0.35 cm³. 3 / g, with an average pore size of 15–30 nm.

[0013] A second aspect of this invention provides a method for preparing a dimethyl maleate hydrogenation catalyst, comprising:

[0014] (1) Co-precipitate an acidic solution containing copper and manganese with an alkaline precipitant in a co-flow manner. After the reaction is completed, the solution is aged and dried to obtain the Cu-Mn precursor.

[0015] (2) Prepare a polyvinyl alcohol (PVA) aqueous solution, mix it with the Cu-Mn precursor and soluble aluminum salt obtained in step (1), stir, and obtain a spinning solution;

[0016] (3) Electrospinning was performed using the spinning solution obtained in step (2) to obtain the catalyst precursor;

[0017] (4) The catalyst precursor obtained in step (3) is calcined and post-treated to obtain the catalyst.

[0018] Further, in step (1), in the acidic solution containing copper and manganese, the copper source can be a soluble copper salt, and the manganese source can be a soluble manganese salt. The soluble copper salt is one or more of copper nitrate trihydrate, copper sulfate, copper acetate, and copper chloride. The soluble manganese salt is one or more of manganese nitrate hexahydrate, manganese sulfate, and manganese acetate.

[0019] Further, in step (1), the concentration of copper in the acidic solution is 0.1 to 5.0 mol / L, and the concentration of manganese is 0.02 to 1.0 mol / L.

[0020] Further, in step (1), the alkaline precipitant is one or more of sodium carbonate solution, sodium bicarbonate solution, ammonia water, and sodium hydroxide solution. The concentration of the alkaline precipitant is 0.5–5 mol / L.

[0021] Further, in step (1), the reaction conditions for coprecipitation are: reaction temperature of 25-80℃, reaction time of 0.2-5h, and pH value of 5.0-9.0.

[0022] Furthermore, in step (1), the aging temperature is 40-80°C and the aging time is 0.5-5 hours.

[0023] Further, in step (1), before drying after aging, the Cu-Mn precursor is preferably obtained through filtration, washing, and other treatments. The filtration and washing can be carried out using conventional methods in the art. The drying conditions are as follows: drying at 50–90°C for 5–15 hours.

[0024] Further, in step (2), the polyvinyl alcohol is 10000 to 120000.

[0025] Further, in step (2), the preparation of the polyvinyl alcohol aqueous solution specifically involves adding polyvinyl alcohol to water (preferably deionized water) and heating it. The mass content of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 5wt% to 25wt%, preferably 10wt% to 15wt%; the heating conditions are: heating at 60 to 85°C for 0.5 to 5.0 hours. Water bath heating is preferred.

[0026] Further, in step (2), the soluble aluminum salt is one or more of aluminum nitrate nonahydrate, aluminum sulfate, aluminum chloride, and aluminum hydroxychloride.

[0027] Further, in step (2), the mass of soluble aluminum salt contained in each milliliter of polyvinyl alcohol aqueous solution is 0.025 to 0.25 g, and the mass of Cu-Mn precursor contained in each milliliter of polyvinyl alcohol aqueous solution is 0.025 to 0.1 g.

[0028] Further, in step (2), the stirring conditions are: stirring speed of 100 to 1500 rpm and stirring time of 2 to 24 hours.

[0029] Further, in step (3), the conditions for electrospinning are: spinning voltage of 15-30kV, feed speed of 0.5-2.0mL / h, and receiving distance of 10-20cm.

[0030] Further, in step (4), the calcination conditions are: a calcination temperature of 600–800°C and a calcination time of 2–6 hours. The calcination preferably employs a programmed temperature rise, with a heating rate of 2–10°C / min to reach the calcination temperature. The calcination atmosphere is an oxygen-containing atmosphere, such as air.

[0031] Furthermore, in step (4), the post-processing includes processes such as tableting, crushing, and sieving. The post-processing can be carried out using conventional methods in the art. An appropriate amount of graphite may be added during the tableting process. The crushing and sieving involves sieving catalyst particles to a mesh size of 20-40.

[0032] A third aspect of the present invention provides a catalyst prepared by the above method.

[0033] Furthermore, the catalyst comprises oxides of CuO, Al2O3, and Mn.

[0034] Furthermore, based on the weight of the catalyst, the weight contents of each component are as follows: copper content (calculated as CuO) is 40% to 70%, aluminum content (calculated as Al2O3) is 20% to 40%, and manganese content (calculated as MnO) is 5% to 15%.

[0035] Furthermore, the specific surface area of ​​the catalyst is 40–70 m².2 / g, preferably 45-65m 2 / g.

[0036] Furthermore, the catalyst is tested by H2-N2O titration, and the dispersion of metallic Cu is 42% to 70%, such as, but not limited to, 42%, 45%, 50%, 52%, 55%, 58%, 60%, 65%, 70%, etc., and any value within the range formed by any two of these values.

[0037] Furthermore, the catalyst has a pore volume of 0.15–0.35 cm³. 3 / g, with an average pore size of 15–30 nm.

[0038] The fourth aspect of this invention provides an application of the above-mentioned catalyst in the hydrogenation of dimethyl maleate to synthesize 1,4-butanediol and co-produce γ-butyrolactone and tetrahydrofuran.

[0039] Furthermore, the application includes: reacting dimethyl maleate with the catalyst in the presence of hydrogen to produce 1,4-butanediol, co-producing γ-butyrolactone and tetrahydrofuran.

[0040] Furthermore, the catalyst of this invention needs to be reduced and activated before use. The reducing gas is hydrogen, or a mixture of hydrogen and nitrogen, wherein the volume ratio of H2 / N2 is (1-10):(90-99). The reduction temperature is 220-300℃, and the reduction time is 6-24h.

[0041] Furthermore, the reaction conditions are as follows: reaction temperature of 150–300℃, reaction pressure of 1–10 MPa, and volume hourly space velocity of 0.1–2.0 h⁻¹. -1 The molar ratio of hydrogen to dimethyl maleate is 100–300:1.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] (1) The catalyst of the present invention is used for the hydrogenation of dimethyl maleate to 1,4-butanediol and co-production of γ-butyrolactone and tetrahydrofuran, with high conversion rate and target product selectivity.

[0044] (2) The preparation method of the present invention, combined with the electrospinning process, can uniformly embed Cu-Mn precursor into polyvinyl alcohol electrospinned fiber. At the same time, soluble aluminum salt is added during the electrospinning process of Cu-Mn precursor, which makes the contact between Cu and support Al more sufficient, which is conducive to the generation of strong metal-support interaction between Cu-Al, which can promote the uniform dispersion of active metal Cu and improve the dispersion of active metal. It is also conducive to the final catalyst having a suitable specific surface area, pore volume and average pore size. When used for the hydrogenation of dimethyl maleate to 1,4-butanediol and the co-production of γ-butyrolactone and tetrahydrofuran, it has a high conversion rate and target product selectivity. Detailed Implementation

[0045] The technical solution of the present invention will be described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments. In the present invention, wt% is a mass fraction.

[0046] In this invention, an ASAP 2425 (McClone Systems, Inc., USA) physical adsorption analyzer was used to test specific surface area, pore volume, and pore size. Specific surface area was analyzed using the BET method; pore size distribution was calculated using BJH and DFT theoretical models based on the adsorption data.

[0047] In this invention, a PANalytical Axios X-ray fluorescence spectrometer was used to analyze the types and contents of elements.

[0048] In this invention, the metal dispersion was tested using an AutoChem II 2920 (McClone Systems, Inc., USA) chemisorption analyzer via H2-N2O titration. The specific test method is as follows:

[0049] (a) Weigh 100 mg of the catalyst sample to be tested and place it in a U-shaped quartz tube. Pre-treat it at 450 °C for 1 h under an inert atmosphere, and then cool it to room temperature. Under a mixed atmosphere of 10% H2 / 90% Ar by volume, raise the temperature to 800 °C at a rate of 10 °C / min and measure the amount of H2 consumed, X, to determine the total number of Cu atoms in the catalyst sample.

[0050] (b) The reduced catalyst was purged and cooled to 50°C under an inert atmosphere. The volume fraction was changed to 10% N2O / 90% Ar and reacted for 1 h. The metal Cu on the surface of the catalyst sample was oxidized to Cu2O (2Cu+N2O→Cu2O+N2). Then, the residual N2O was purged clean under an inert atmosphere.

[0051] (c) After the oxidation step, a H2 programmed temperature reduction process is carried out. Under a mixed atmosphere of 10% H2 / 90% Ar by volume, the temperature is increased to 800℃ at a rate of 10℃ / min. The amount of H2 consumed, Y, is measured to determine the number of Cu atoms on the surface of the catalyst sample.

[0052] The formula for calculating the dispersion of metallic Cu is: Dispersion (%) = 2Y / X × 100%.

[0053] Example 1

[0054] (1) Dissolve copper nitrate trihydrate (1 mol) and manganese nitrate hexahydrate (0.14 mol) in deionized water (1 L) to prepare an acid solution, and dissolve sodium carbonate (1 mol) in deionized water (1 L) to prepare an alkaline precipitant. Under stirring and at 70 °C, the acid solution and the alkaline precipitant aqueous solution were subjected to a coprecipitation reaction for 30 min, with pH controlled at 7.0. After the coprecipitation reaction was completed, the mixture was aged at 70 °C for 2 h, filtered, washed with water 6 times, and dried at 80 °C for 12 h to obtain the Cu-Mn precursor.

[0055] (2) Add 6g PVA (molecular weight 80000) to 60mL of deionized water, heat in a water bath to 80℃ and stir for 2h to obtain PVA aqueous solution. Take 20mL of the above PVA aqueous solution, add 4g of aluminum nitrate nonahydrate and 1.6g of Cu-Mn precursor obtained in step (1), and magnetically stir at 1000rpm for 12h to obtain spinning solution.

[0056] (3) Electrospinning was performed to prepare the catalyst precursor according to the following parameters: the spinning voltage was controlled at 20kV, the propulsion speed was 2.0mL / h, and the receiving distance was 15cm.

[0057] (4) The catalyst precursor fiber obtained in step (3) is calcined at 700℃ in an air atmosphere at a heating rate of 5℃ / min for 2 hours. Graphite is added to the obtained catalyst powder, which is then pressed into tablets, pulverized, and sieved to obtain 20-40 mesh particles to form catalyst A1. The physicochemical properties of catalyst A1 are shown in Table 1.

[0058] Example 2

[0059] (1) Dissolve copper nitrate (1 mol) and manganese nitrate (0.14 mol) in deionized water (1 L) to prepare an acid solution, and dissolve sodium carbonate (1 mol) in deionized water (1 L) to prepare an alkaline precipitant. Under stirring and at 70 °C, the acid solution and the alkaline precipitant aqueous solution were subjected to a co-precipitation reaction for 30 min, with pH controlled at 7.0. After the co-precipitation reaction was completed, the mixture was aged at 70 °C for 2 h. After filtration, washing with water 6 times, and drying at 80 °C for 12 h, the Cu-Mn precursor was obtained.

[0060] (2) Add 6g PVA (molecular weight 80000) to 60mL of deionized water, heat in a water bath to 80℃ and stir for 2h to obtain PVA aqueous solution. Take 20mL of the above PVA aqueous solution, add 1.42g of anhydrous aluminum chloride and 1.6g of Cu-Mn precursor obtained in step (1), and magnetically stir at 1000rpm for 12h to obtain spinning solution.

[0061] (3) Electrospinning was performed to prepare the catalyst precursor according to the following parameters: the spinning voltage was controlled at 20kV, the propulsion speed was 2.0mL / h, and the receiving distance was 15cm.

[0062] (4) The catalyst precursor obtained in step (3) is calcined at 650°C in an air atmosphere at a heating rate of 5°C / min for 2 hours. Graphite is added to the resulting catalyst powder, which is then pressed into tablets, pulverized, and sieved to obtain 20-40 mesh particles to form catalyst A2. The physicochemical properties of catalyst A2 are shown in Table 1.

[0063] Example 3

[0064] (1) Dissolve 1 mol of copper nitrate trihydrate and 0.15 mol of manganese nitrate hexahydrate in 1 L of deionized water to prepare an acid solution, and dissolve 1 mol of sodium carbonate in 1 L of deionized water to prepare an alkaline precipitant. Coprecipitate the acid solution and the alkaline precipitant solution at 70 °C for 30 min under stirring and control pH = 8.0. After the coprecipitation reaction is completed, age at 70 °C for 2 h, filter, wash with water 6 times, and dry at 80 °C to obtain Cu-Mn precursor.

[0065] (2) Add 6g of PVA (molecular weight 80000) to 60mL of deionized water, heat in a water bath to 80℃ and stir for 2h to obtain PVA aqueous solution. Take 20mL of the above PVA aqueous solution, add 8g of aluminum nitrate nonahydrate and 3.2g of Cu-Mn precursor obtained in step (1), and magnetically stir at 1000rpm for 12h to obtain spinning solution.

[0066] (3) Electrospinning was performed to prepare the catalyst precursor according to the following parameters: the spinning voltage was controlled at 20kV, the propulsion speed was 2.0mL / h, and the receiving distance was 15cm.

[0067] (4) The catalyst precursor fiber obtained in step (3) is calcined at 700℃ in an air atmosphere at a heating rate of 5℃ / min for 2 hours. Graphite is added to the obtained catalyst powder, which is then pressed into tablets, pulverized, and sieved to obtain 20-40 mesh particles to form catalyst A3. The physicochemical properties of catalyst A3 are shown in Table 1.

[0068] Example 4

[0069] (1) Dissolve 1 mol of copper nitrate trihydrate and 0.15 mol of manganese nitrate hexahydrate in 1 L of deionized water to prepare an acid solution, and dissolve 1 mol of sodium carbonate in 1 L of deionized water to prepare an alkaline precipitant. Coprecipitate the acid solution and the alkaline precipitant solution at 70 °C for 30 min under stirring and at pH = 7.0. After the coprecipitation reaction is completed, age the product at 70 °C for 2 h, filter, wash with water 6 times, and dry at 80 °C for 12 h to obtain the Cu-Mn precursor.

[0070] (2) Add 6g PVA (molecular weight 80000) to 60mL of deionized water, heat in a water bath to 80℃ and stir for 2h to obtain PVA aqueous solution. Take 20mL of the above PVA aqueous solution, add 4g of aluminum nitrate nonahydrate and 1.6g of Cu-Mn precursor obtained in step (1), and magnetically stir at 1000rpm for 12h to obtain spinning solution.

[0071] (3) Electrospinning was performed to prepare the catalyst precursor according to the following parameters: the spinning voltage was controlled at 30kV, the propulsion speed was 1.5mL / h, and the receiving distance was 20cm.

[0072] (4) The catalyst precursor fiber obtained in step (3) is calcined at 700℃ in an air atmosphere at a heating rate of 5℃ / min for 2 hours. Graphite is added to the resulting catalyst powder, which is then pressed into tablets, pulverized, and sieved to obtain 20-40 mesh particles to form catalyst A4. The physicochemical properties of catalyst A4 are shown in Table 1.

[0073] Example 5

[0074] (1) Dissolve copper acetate (1 mol) and manganese acetate (0.15 mol) in deionized water (1 L) to prepare an acid solution, and dissolve sodium bicarbonate (1 mol) in deionized water (1 L) to prepare an alkaline precipitant. Under stirring and at 70 °C, the acid solution and the alkaline precipitant aqueous solution were subjected to a coprecipitation reaction for 60 min, with pH controlled at 7.5. After the coprecipitation reaction was completed, the mixture was aged at 75 °C for 2 h, filtered, washed with water 6 times, and dried at 80 °C for 12 h to obtain the Cu-Mn precursor.

[0075] (2) Add 6g PVA (molecular weight 80000) to 60mL of deionized water, heat in a water bath to 80℃ and stir for 2h to obtain PVA aqueous solution. Take 20mL of the above PVA aqueous solution, add 4g aluminum nitrate and 1.1g Cu-Mn precursor obtained in step (1), and magnetically stir at 1000rpm for 12h to obtain spinning solution.

[0076] (3) Electrospinning was performed to prepare the catalyst precursor according to the following parameters: the spinning voltage was controlled at 20kV, the propulsion speed was 2.0mL / h, and the receiving distance was 15cm.

[0077] (4) The catalyst precursor fiber obtained in step (3) is heat-treated at 700℃ in an air atmosphere at a heating rate of 5℃ / min for 2 hours. Graphite is added to the resulting catalyst powder, which is then pressed into tablets, pulverized, and sieved to obtain 20-40 mesh particles to form catalyst A5. The physicochemical properties of catalyst A5 are shown in Table 1.

[0078] Comparative Example 1

[0079] (1) Dissolve 1 mol of copper nitrate trihydrate and 0.15 mol of manganese nitrate hexahydrate in 1 L of deionized water to prepare an acid solution, and dissolve 1 mol of sodium carbonate in 1 L of deionized water to prepare an alkaline precipitant. Coprecipitate the acid solution and the alkaline precipitant solution at 70 °C for 30 min under stirring and at pH = 7.0. After the coprecipitation reaction is completed, age the product at 70 °C for 2 h, filter, wash with water 6 times, and dry at 80 °C for 12 h to obtain the Cu-Mn precursor.

[0080] (2) Weigh 1.6g of Cu-Mn precursor obtained in step (1), add 4g of aluminum nitrate nonahydrate and 50mL of water to it, stir magnetically at 1000rpm for 2h, filter, wash with deionized water 6 times, and dry at 80℃ for 12h to obtain catalyst precursor.

[0081] (3) The catalyst precursor fiber obtained in step (2) is calcined at 700℃ in an air atmosphere at a heating rate of 5℃ / min for 2 hours. Graphite is added to the obtained catalyst powder, which is then pressed into tablets, pulverized, and sieved to obtain 20-40 mesh particles to form catalyst B1. The physicochemical properties of catalyst B1 are shown in Table 1.

[0082] Comparative Example 2

[0083] (1) Dissolve 1 mol of copper nitrate trihydrate and 0.15 mol of manganese nitrate hexahydrate in 1 L of deionized water to prepare an acid solution, and dissolve 1 mol of sodium carbonate in 1 L of deionized water to prepare an alkaline precipitant. Coprecipitate the acid solution and the alkaline precipitant solution at 70 °C for 30 min under stirring and at pH = 7.0. After the coprecipitation reaction is completed, age the product at 70 °C for 2 h, filter, wash with water 6 times, and dry at 80 °C for 12 h to obtain the Cu-Mn precursor.

[0084] (2) Add 2g PVA (molecular weight 80000) to 60mL of deionized water, heat in a water bath to 80℃ and stir for 2h to obtain PVA aqueous solution. Take 20mL of the above PVA aqueous solution, add 4g of aluminum nitrate nonahydrate and 1.6g of Cu-Mn precursor obtained in step (1), and magnetically stir at 1000rpm for 12h to obtain spinning solution.

[0085] (3) Electrospinning was performed to prepare the catalyst precursor according to the following parameters: the spinning voltage was controlled at 20kV, the propulsion speed was 2.0mL / h, and the receiving distance was 15cm.

[0086] (4) The catalyst precursor fiber obtained in step (3) is calcined at 700℃ in an air atmosphere at a heating rate of 5℃ / min for 2 hours. Graphite is added to the resulting catalyst powder, which is then pressed into tablets, pulverized, and sieved to obtain 20-40 mesh particles to form catalyst B2. The physicochemical properties of catalyst B2 are shown in Table 1.

[0087] Application examples

[0088] The catalysts prepared in Examples 1-5 and Comparative Examples 1-3 were used for the hydrogenation of dimethyl maleate to 1,4-butanediol, co-producing γ-butyrolactone and tetrahydrofuran. Before use, the catalysts were reduced with hydrogen under the following conditions: hydrogen pressure 0.1 MPa, reduction temperature 270 °C, and reduction time 12 h. After reduction, the reaction was carried out under the following conditions: reaction temperature 190 °C; feed hourly space velocity 0.25 h⁻¹. -1 The H2 / ester molar ratio was 200:1; the reaction pressure was 6 MPa. The reaction results are shown in Table 2.

[0089] Table 1. Composition and properties of catalysts obtained in each example.

[0090]

[0091] Table 2 Catalyst Evaluation Results for Each Example

[0092]

[0093] *Note: In Table 2, the target products are 1,4-butanediol, γ-butyrolactone, and tetrahydrofuran.

[0094] It should be emphasized that the above-mentioned content is only a specific embodiment of the present invention and should not be construed as limiting the present invention to the above description in specific implementation. For those skilled in the art, any simple deductions and improvements made without departing from the spirit and principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A hydrogenation catalyst for dimethyl maleate, characterized in that, The catalyst comprises oxides of CuO, Al2O3, and Mn; the specific surface area of ​​the catalyst is 40–70 m². 2 / g, preferably 45-65m 2 / g; the catalyst was tested by H2-N2O titration, and the dispersion of metallic Cu was 42% to 70%.

2. The catalyst according to claim 1, characterized in that, Based on the weight of the catalyst, the weight contents of each component are as follows: copper content (calculated as CuO) is 40%–70%, aluminum content (calculated as Al2O3) is 20%–40%, and manganese content (calculated as MnO) is 5%–15%.

3. The catalyst according to claim 1, characterized in that, The catalyst has a pore volume of 0.15–0.35 cm³. 3 / g, with an average pore size of 15–30 nm.

4. A method for preparing a hydrogenation catalyst for dimethyl maleate, characterized in that, include: (1) Co-precipitate an acidic solution containing copper and manganese with an alkaline precipitant in a co-flow manner. After the reaction is completed, the solution is aged and dried to obtain the Cu-Mn precursor. (2) Prepare a polyvinyl alcohol aqueous solution, mix it with the Cu-Mn precursor and soluble aluminum salt obtained in step (1), stir, and obtain a spinning solution; (3) Electrospinning was performed using the spinning solution obtained in step (2) to obtain the catalyst precursor; (4) The catalyst precursor obtained in step (3) is calcined and post-treated to obtain the catalyst.

5. The method according to claim 4, characterized in that, In step (1), in the acidic solution containing copper and manganese, the copper source is a soluble copper salt, and the manganese source is a soluble manganese salt; the soluble copper salt is preferably one or more of copper nitrate trihydrate, copper sulfate, copper acetate, and copper chloride; the soluble manganese salt is preferably one or more of manganese nitrate hexahydrate, manganese sulfate, and manganese acetate. And / or, in step (1), the concentration of copper in the acidic solution is 0.1 to 5.0 mol / L and the concentration of manganese is 0.02 to 1.0 mol / L. And / or, in step (1), the alkaline precipitant is one or more of sodium carbonate solution, sodium bicarbonate solution, ammonia water, and sodium hydroxide solution; And / or, the concentration of the alkaline precipitant is 0.5–5 mol / L.

6. The method according to claim 4, characterized in that, In step (1), the reaction conditions for coprecipitation are: reaction temperature of 25-80℃, reaction time of 0.2-5h, and pH value of 5.0-9.

0.

7. The method according to claim 4, characterized in that, In step (1), the aging temperature is 40-80℃ and the aging time is 0.5-5h; and / or the drying conditions are as follows: drying at 50-90℃ for 5-15h.

8. The method according to claim 4, characterized in that, In step (2), the polyvinyl alcohol is 10,000 to 120,000; And / or, in step (2), the soluble aluminum salt is one or more of aluminum nitrate nonahydrate, aluminum sulfate, aluminum chloride, and aluminum hydroxychloride.

9. The method according to claim 4, characterized in that, In step (2), the mass of soluble aluminum salt contained in each milliliter of polyvinyl alcohol aqueous solution is 0.025 to 0.25 g, and the mass of Cu-Mn precursor contained in each milliliter of polyvinyl alcohol aqueous solution is 0.025 to 0.1 g. And / or, in step (2), the stirring conditions are: stirring speed of 100 to 1500 rpm and stirring time of 2 to 24 hours.

10. The method according to claim 4, characterized in that, In step (3), the conditions for electrospinning are: spinning voltage of 15-30kV, feed speed of 0.5-2.0mL / h, and receiving distance of 10-20cm.

11. The method according to claim 4, characterized in that, In step (4), the calcination conditions are: calcination temperature of 600-800℃, calcination time of 2-6h; the calcination preferably adopts programmed heating, and the heating rate to the calcination temperature is 2-10℃ / min; the calcination atmosphere is an oxygen-containing atmosphere.

12. The application of a catalyst according to any one of claims 1-3 or a catalyst prepared by any one of claims 4-11 in the hydrogenation of dimethyl maleate to synthesize 1,4-butanediol and co-produce γ-butyrolactone and tetrahydrofuran.

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