A supported copper-based catalyst for the hydrogenation of 1,4-butenediol to 1,4-butanediol, its preparation method and application

Abstract

This invention belongs to the field of supported copper-based catalyst technology, and particularly relates to a supported copper-based catalyst for the hydrogenation of 1,4-butenediol to 1,4-butanediol, its preparation method and application. The catalyst has a supported structure, the support is γ-Al2O3, and the active component is metallic Cu. The loading of Cu is 5% to 15% by the total mass of the catalyst.

Description

Technical Field

[0001] This invention belongs to the field of supported copper-based catalyst technology, and particularly relates to a supported copper-based catalyst for the hydrogenation of 1,4-butenediol to 1,4-butanediol, its preparation method and application. Background Technology

[0002] 1,4-Butanediol is a core raw material for the production of chemical products such as PBT resin, polyurethane, tetrahydrofuran, and γ-butyrolactone. The mainstream domestic production route uses the acetylacetonate-aldehyde process, first synthesizing 1,4-butynediol from acetylene and formaldehyde, then hydrogenating it in stages to obtain 1,4-butanediol. 1,4-Butenediol, as an intermediate hydrogenation product, directly determines the raw material utilization rate and production cost of the entire process through its catalytic conversion efficiency. Currently, industrial catalysts used for the hydrogenation of 1,4-butenediol are mainly divided into three categories: Raney nickel catalysts, noble metal catalysts, and ordinary copper-based catalysts. Raney nickel catalysts require harsh reaction conditions, including high temperature and high pressure, resulting in high equipment investment and energy consumption. Platinum and palladium noble metal catalysts have high raw material costs, making large-scale continuous production economically unfeasible. While conventional supported copper-based catalysts use inexpensive and readily available raw materials, they generally suffer from poor dispersion of active metals and easy sintering and agglomeration of copper grains, leading to incomplete raw material conversion and easy occurrence of hydrogenolysis and isomerization side reactions, significantly reducing the selectivity of 1,4-butanediol products.

[0003] Existing γ-Al₂O₃ supported copper-based catalysts are mostly prepared using conventional impregnation processes. The impregnation process relies solely on natural diffusion for copper ion adsorption, making it difficult for the metal precursor to uniformly enter the support pores. Copper species tend to accumulate locally on the support surface, leading to significant pore blockage and a substantial decrease in the catalyst's specific surface area and the number of effective active sites. When applied to fixed-bed continuous hydrogenation systems, these catalysts exhibit low 1,4-butenediol conversion and high byproduct formation within the conventional reaction range of 120–160 °C and 1–4 MPa. Furthermore, their activity decays rapidly over long periods, making it difficult to balance high conversion, high selectivity, and stable operation. This fails to meet the demands of industrial continuous production for low-cost, high-performance catalysts. Summary of the Invention

[0004] In view of the aforementioned problems, and in conjunction with the first aspect of the present invention, embodiments of the present invention provide a supported copper-based catalyst for the hydrogenation of 1,4-butenediol to 1,4-butanediol, wherein the catalyst has a supported structure, the support is γ-Al2O3, and the active component is metallic Cu; The loading of Cu is 5% to 15% based on the total mass of the catalyst.

[0005] A method for preparing a supported copper-based catalyst for the hydrogenation of 1,4-butenediol to 1,4-butanediol, employing an equal-volume impregnation method, includes the following steps: Step S11: Weigh the soluble copper salt according to the target Cu loading. Dissolve it in deionized water to prepare an impregnation solution, the volume of which matches the saturated water absorption rate of the γ-Al2O3 support; Step S12: Add the γ-Al2O3 support to the impregnation solution and mix well. Then sonicate for 2 hours to allow copper ions to be adsorbed into the pores of the support. Step S13: After impregnation, the mixture is dried at 90°C to remove water, and then calcined at 500°C for 4 hours at a rate of 5°C / min to decompose copper nitrate into copper oxide. Step S14: The solid obtained from calcination is pressed into tablets, crushed, and sieved to obtain catalyst particles of 40-60 mesh.

[0006] Preferably, the soluble copper salt is copper nitrate trihydrate. .

[0007] Preferably, the drying operation in step S13 is performed overnight in an oven at 90°C.

[0008] Preferably, the catalyst is loaded into a fixed-bed reactor and pre-reduced with hydrogen before the hydrogenation catalytic reaction.

[0009] Preferably, the hydrogen pre-reduction conditions are as follows: Hydrogen flow rate 30 mL / min, temperature increased to 250 °C for 3 h reduction.

[0010] Preferably, the hydrogenation reaction process conditions are: reaction temperature 120-160℃, reaction pressure 1-4MPa, hydrogen-to-oil volume ratio 600-900, liquid feed flow rate 0.03-0.06mL / min, and catalyst loading amount 2mL.

[0011] Preferably, the preferred process conditions for the hydrogenation reaction are: reaction temperature 150℃, reaction pressure 3MPa, and hydrogen-to-oil volume ratio 800.

[0012] Based on the above, the preparation process employing equal-volume impregnation combined with ultrasound assistance allows the copper precursor to diffuse and adsorb uniformly into the internal pores of the γ-Al₂O₃ support, effectively preventing local aggregation of active components, improving copper species dispersion, and broadening the number of effective active sites on the catalyst. By limiting the copper loading mass fraction to 5%–15%, sufficient hydrogenation active centers are ensured while suppressing the high-temperature sintering phenomenon of copper grains under high loading. In the fixed-bed hydrogenation system, 1,4-butenediol can achieve high conversion, while significantly suppressing side reactions such as cracking and isomerization, ensuring that the 1,4-butenediol product maintains high selectivity.

[0013] The catalyst prepared in this invention uses only copper nitrate trihydrate and alumina as raw materials. These materials are readily available, the preparation process is simple, and no complex additives or special equipment are required, resulting in low industrial-scale production costs. The accompanying limited pre-reduction and hydrogenation reaction processes are suitable for fixed-bed continuous production systems. The catalyst has a wide operating window, operating stably within a temperature range of 120–160°C and a pressure range of 1–4 MPa. The catalyst exhibits slow activity decay during continuous operation, demonstrating excellent cycle and long-term stability, making it suitable for large-scale industrial continuous production of 1,4-butanediol. Attached Figure Description

[0014] Figure 1 : Flowchart of this invention.

[0015] Figure 2 (a) 1,4-Butenediol conversion of catalysts in Examples 1, 2, and 3 of the present invention and Comparative Examples 1 and 2 (temperature 150°C, pressure 3 MPa, hydrogen-to-oil ratio 800); (b) 1,4-Butenediol selectivity of catalysts in Examples 1, 2, and 3 of the present invention (temperature 150°C, pressure 3 MPa, hydrogen-to-oil ratio 800); (c) 1,4-Butenediol conversion of catalyst in Example 1 of the present invention at different reaction temperatures (pressure 3 MPa, hydrogen-to-oil ratio 800); (d) 1,4-Butenediol conversion of catalyst in Example 1 of the present invention at different hydrogen-to-oil ratios (temperature 150°C, pressure 3 MPa); (e) 1,4-Butenediol conversion of catalyst in Example 1 of the present invention at different reaction pressures (temperature 150°C, hydrogen-to-oil ratio 800). Figure 3 XRD spectra of the catalysts (5%-15% Cu / γ-Al2O3) in Examples 1-3 of this invention; Figure 4 SEM image and STM-EDS elemental mapping image of the catalyst in Example 1 of this invention; Figure 5 SEM image and STM-EDS elemental mapping image of the catalyst of Comparative Example 1 of this invention.

[0016] Figure 6 Examples 1, 2, 3 and Comparative Example 1: (a) N2- adsorption-desorption curves and (b) pore size distribution diagrams. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings.

[0018] The catalyst is a supported catalyst, with γ-Al2O3 as the support and Cu as the active component; based on the total mass of the catalyst, the Cu loading is 5%~15%; The preparation method employs an equal-volume impregnation method, specifically including the following steps: S1. Preparation of impregnation solution: Weigh out the soluble copper salt according to the target loading. The γ-Al2O3 carrier is dissolved in deionized water to prepare an impregnation solution of a certain volume; the volume of the impregnation solution is determined based on the saturated water absorption rate of the γ-Al2O3 carrier.

[0019] S2. Equal volume impregnation: Add the γ-Al2O3 support to the impregnation solution, stir evenly, and sonicate for 2 hours to allow copper ions to be fully adsorbed into the pores of the support.

[0020] S3. Drying and calcination: The mixture obtained in step S2 is dried overnight in an oven at 90°C to remove moisture; then the dried powder is placed in a muffle furnace and calcined at 5°C / min to 500°C for 4 hours to decompose copper nitrate into copper oxide.

[0021] S4. Molding: The calcined catalyst is pressed into tablets, crushed, and sieved to 40-60 mesh to obtain the catalyst.

[0022] This invention provides a method for testing the above-mentioned catalyst in a fixed-bed reactor during the hydrogenation of 1,4-butenediol to 1,4-butanediol.

[0023] The specific application is as follows: the catalyst is reduced in a fixed-bed reactor at 250°C for 3 hours in a hydrogen atmosphere (H2 flow rate 30 mL / min), and then used to catalyze the reaction of 1,4-butenediol and hydrogen to produce 1,4-butanediol.

[0024] The reaction conditions are: reaction temperature 120~160℃, reaction pressure 1~4MPa, hydrogen-to-oil ratio (volume ratio) 600~900, and liquid feed flow rate 0.03~0.06 mL / min (catalyst loading amount 2mL). Example 1: Preparation of 10% Cu / γ-Al2O3 catalyst; Weigh out 4.5 g of γ-Al₂O₃ support and 1.9 g of Cu(NO₃)₂. 3H2O. Put 1.9g Cu(NO3)2 Dissolve 3H2O in 3.6 mL of deionized water to prepare an impregnation solution.

[0025] The γ-Al₂O₃ support was added to the impregnation solution, stirred until homogeneous, and then sonicated for 2 hours. The mixture was then dried overnight in a 90°C oven.

[0026] The dried powder was transferred to a muffle furnace and heated to 500°C at a rate of 5°C / min for 4 hours, then allowed to cool naturally.

[0027] The calcined catalyst was pressed into tablets, crushed, and sieved to obtain a 40-60 mesh catalyst, denoted as 10% Cu / γ-Al2O3.

[0028] Example 2: Preparation of 5% Cu / γ-Al2O3 catalyst; The steps are the same as in Example 1, except that the Cu loading is 5%. Weigh 4.75g of γ-Al₂O₃ support and Cu(NO₃)₂. 0.95 g of 3H₂O was dissolved in 3.8 mL of deionized water. The remaining steps were the same, and the resulting catalyst was denoted as 5% Cu / γ-Al₂O₃.

[0029] Example 3: Preparation of 15% Cu / γ-Al2O3 catalyst; The steps are the same as in Example 1, except that the Cu loading is 15%. Weigh 4.25g of γ-Al₂O₃ support and Cu(NO₃)₂. 2.85 g of 3H₂O was dissolved in 3.4 mL of deionized water. The remaining steps were the same, and the resulting catalyst was designated as 15% Cu / γ-Al₂O₃.

[0030] Comparative Example 1: Weigh 5g of γ-Al2O3 support and calcine it directly at 500℃ for 4 hours to obtain pure γ-Al2O3 catalyst. Press, crush, and sieve to 40~60 mesh and denote it as γ-Al2O3.

[0031] Comparative Example 1: The steps and raw material amounts are the same as in Example 1, except that the ultrasonic step is omitted, and the resulting catalyst is named 10%Cu / γ-Al2O3; Catalyst performance evaluation: The catalysts prepared in the above embodiments and comparative examples were tableted and sieved. 2 ml of 40-60 mesh catalyst particles were packed into a fixed-bed microreactor. First, in an H2 atmosphere, the temperature was increased to 250°C at 3°C / min, and reduction was carried out for 3 hours. After reduction, under an N2 atmosphere, the reaction temperature was reached, hydrogen was introduced, the system pressure was adjusted to 3.0 MPa, the feed flow rate was 0.03 ml / min, and the hydrogen-to-oil ratio was 800:1, and the reaction was initiated. The reaction products were analyzed online by gas chromatography. The evaluation results are attached. Figure 2 As shown.

[0032] Depend on Figure 2 The data show that the catalyst in Example 1 (10% loading) exhibits the best overall performance, with the highest 1,4-butenediol conversion and 1,4-butenediol selectivity.

[0033] In summary, this invention provides a supported copper-based catalyst for the hydrogenation of 1,4-butenediol to 1,4-butanediol, prepared using γ-Al₂O₃ as a support via an equal-volume impregnation method. By optimizing the copper loading and reaction conditions, high efficiency (>95.6%) and high selectivity (>99%) of 1,4-butenediol were achieved. The catalyst preparation process is simple, low-cost, and exhibits good stability, demonstrating significant promise for industrial applications.

[0034] It should be noted that, in order to simplify the description of the present invention and thus help to understand one or more embodiments of the invention, multiple features may sometimes be grouped into one embodiment, drawing or description thereof in the foregoing description of the embodiments of the present invention.

[0035] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A supported copper-based catalyst for the hydrogenation of 1,4-butenediol to 1,4-butanediol, characterized in that: The catalyst has a supported structure, with γ-Al2O3 as the support and metallic Cu as the active component. The loading of Cu is 5% to 15% based on the total mass of the catalyst.

2. A method for preparing a supported copper-based catalyst for the hydrogenation of 1,4-butenediol to 1,4-butanediol according to claim 1, characterized in that: The equal-volume impregnation method includes the following steps: Step S11: Weigh the soluble copper salt according to the target Cu loading. Dissolve it in deionized water to prepare an impregnation solution, the volume of which matches the saturated water absorption rate of the γ-Al2O3 support; Step S12: Add the γ-Al2O3 support to the impregnation solution and mix well. Then sonicate for 2 hours to allow copper ions to be adsorbed into the pores of the support. Step S13: After impregnation, the mixture is dried at 90°C to remove water, and then calcined at 500°C for 4 hours at a rate of 5°C / min to decompose copper nitrate into copper oxide. Step S14: The solid obtained from calcination is pressed into tablets, crushed, and sieved to obtain catalyst particles of 40-60 mesh.

3. The method for preparing a supported copper-based catalyst for the hydrogenation of 1,4-butenediol to 1,4-butanediol according to claim 2, characterized in that: The soluble copper salt is copper nitrate trihydrate. .

4. The method for preparing a supported copper-based catalyst for the hydrogenation of 1,4-butenediol to 1,4-butanediol according to claim 2, characterized in that: In step S13, the drying process involves drying overnight in an oven at 90°C.

5. The application of the supported copper-based catalyst according to claim 1 in the hydrogenation of 1,4-butenediol to 1,4-butanediol, characterized in that, The catalyst is loaded into a fixed-bed reactor and pre-reduced with hydrogen before undergoing the hydrogenation catalytic reaction.

6. The application according to claim 5, characterized in that, The hydrogen pre-reduction conditions are as follows: Hydrogen flow rate 30 mL / min, temperature increased to 250 °C for 3 h reduction.

7. The application according to claim 5, characterized in that, The hydrogenation reaction process conditions are as follows: reaction temperature 120-160℃, reaction pressure 1-4MPa, hydrogen-to-oil volume ratio 600-900, liquid feed flow rate 0.03-0.06mL / min, and catalyst loading amount 2mL.

8. The application according to claim 7, characterized in that, The preferred process conditions for the hydrogenation reaction are: reaction temperature 150℃, reaction pressure 3MPa, and hydrogen-to-oil volume ratio 800.

Images