Copper-chromium catalyst, its synthesis method and application

Abstract

The application discloses a copper-chromium catalyst and a synthesis method and application thereof. The side pressure strength of the copper-chromium catalyst is 90-120 N per pellet, and the bulk density is 160-195 g / 100 mL. The copper-chromium catalyst has a lower bulk density, a lower weight of 10 pellets and a higher side pressure strength, and can improve the performance of the catalyst in conversion rate and selectivity and the like in the reaction of preparing 1,4-butanediol by hydrogenating dimethyl maleate.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a copper-chromium catalyst, its synthesis method, and its application. Background Technology

[0002] Catalysts play a crucial role in the production of petrochemicals, fine chemicals, and synthetic ammonia. Industrially used catalysts are typically prepared in specific shapes, such as spherical, granular, cylindrical, honeycomb, and irregular shapes (e.g., trilobal, toothed spherical, and porous cylindrical). The specific shape of a catalyst is determined by the catalytic reaction process and the type of reactor. Besides requiring high conversion and selectivity, catalysts should also possess a shape and size suitable for the reaction, as well as good mechanical strength. This ensures good impact resistance and abrasion resistance during use, mitigating damage from loading, heating, gas flow, and the reaction itself.

[0003] Currently, commonly used catalyst forming methods include tableting, extrusion, spray forming, rotational forming, and oil-based forming. Among these, tableting is simple to operate and can produce catalysts with consistent shape, uniform texture, and good mechanical strength. It has wide applications in both pilot-scale and industrial production and is a promising forming method.

[0004] Copper-chromium composite metal oxide (Cu-Cr-O) catalysts are widely used in the hydrogenation of dimethyl maleate (DMM) to prepare 1,4-butanediol. CN105709760B discloses a copper-chromium catalyst, its preparation method, and its application. The method first prepares a copper-chromium mixed solution and an alkaline solution, and then co-precipitates the copper-chromium mixture with the alkaline solution in a co-current flow. Citric acid is added to the remaining copper-chromium solution, and co-precipitation continues in a co-current flow with the alkaline solution. The reaction product is heated to a gel state and then dried at high temperature to obtain a dry gel. This gel is ground into a fine powder, ethanol is added, and the powder is ignited. The product after combustion is the target copper-chromium catalyst. CN117085722A discloses a method for preparing a supported copper-chromium catalyst and its application. First, a nitrogen source, a carbon source, a copper source, and a chromium source are dissolved in water. The pH is adjusted to 8–11, and the mixture is stirred thoroughly. After evaporating the water, the mixture is calcined at 300–800℃ for 2–8 hours to obtain a supported copper-chromium bimetallic catalyst. CN113797933A discloses a copper-chromium catalyst, its preparation method, and its application. The catalyst preparation method includes the following steps: mixing copper oxalate and chromium oxalate with water and reacting them to obtain a gel; then drying and calcining the mixture sequentially after the reaction to obtain the copper-chromium catalyst.

[0005] While the aforementioned copper-chromium catalysts offer significant advantages, including high carbonyl hydrogenation activity and selectivity for target alcohols, they also suffer from drawbacks such as difficulty in molding, low powder compression ratio, poor flowability, high catalyst bulk density after tableting, low strength, and frequent tablet breakage. Particularly in reactions involving a liquid phase, they can easily cause increased system resistance, leading to malfunctions and shortened catalyst life. Therefore, for copper-chromium catalysts, it is crucial to investigate the impact of catalyst preparation methods on tableting performance, starting from the catalyst preparation process itself, to improve both catalytic and tableting performance to industrial application levels. Summary of the Invention

[0006] To address the problems of high bulk density, poor flowability, and low tablet strength in copper-chromium catalyst powders prepared by conventional co-precipitation methods, resulting in high catalyst fragmentation rates and difficulties in tableting, this invention provides a copper-chromium catalyst, its synthesis method, and its applications. The copper-chromium catalyst prepared by this method exhibits low bulk density, low weight per 10 tablets, and high lateral compressive strength. When used in the hydrogenation of dimethyl maleate to 1,4-butanediol, the obtained catalyst improves its performance in terms of conversion and selectivity.

[0007] The first aspect of the present invention provides a copper-chromium catalyst, wherein the side pressure strength of the catalyst is 90-120 N / particle, preferably 90-110 N / particle, and the bulk density of the catalyst is 160-195 g / 100 mL, preferably 170-190 g / 100 mL.

[0008] Furthermore, the copper-chromium catalyst comprises CuO and Cr2O3, and the weight content of each component is as follows, based on the weight of the catalyst: CuO is 40-57 wt%, and Cr2O3 is 40-57 wt%.

[0009] Furthermore, the copper-chromium catalyst also includes a forming aid, such as graphite, with the content of the forming aid being 0.1 to 5 wt% based on the weight of the catalyst.

[0010] Furthermore, the copper-chromium catalyst, based on a cylindrical shaped catalyst with a diameter of 3 mm and a height of 3.2 ± 0.2 mm, has a weight of 10 catalyst particles (total weight of 10 catalyst particles) of 0.70–0.90 g, preferably 0.75–0.87 g.

[0011] A second aspect of the present invention provides a method for synthesizing a copper-chromium catalyst, comprising:

[0012] (1) Mix copper source and chromium source with polyethylene glycol to obtain a mixture;

[0013] (2) The mixture obtained in step (1) is reacted with a precipitant in a co-current reaction. After the reaction is completed, the mixture is aged and then post-treated to obtain a catalyst precursor. CO2 is continuously introduced during the co-current reaction and / or aging process.

[0014] (3) The catalyst precursor obtained in step (2) is calcined to obtain an unformed catalyst, which is then pressed into tablets to obtain a copper-chromium catalyst.

[0015] Further, in step (1), the copper source is a conventional soluble copper salt in the art, preferably one or more of copper nitrate, copper acetate, copper chloride, and copper sulfate. The chromium source is a conventional soluble chromium salt in the art, preferably one or more of chromic anhydride, chromium nitrate, and chromium chloride.

[0016] Furthermore, in step (1), it is preferable to first mix the copper source and chromium source with water to obtain a metal salt solution, and then mix it with polyethylene glycol to obtain a mixture.

[0017] Furthermore, in step (1), the concentration of copper ions in the metal salt solution containing copper and chromium sources is 0.05–5 mol / L, and the concentration of chromium ions is 0.05–5 mol / L.

[0018] Furthermore, in step (1), the molecular weight of the polyethylene glycol can be 1000 to 10000.

[0019] Further, in step (1), the mass concentration of polyethylene glycol in the mixture is 0.05 to 0.4 g / mL, preferably 0.1 to 0.4 g / mL.

[0020] Further, in step (2), the precipitant is one or more of sodium carbonate solution, sodium bicarbonate solution, ammonia water, and sodium hydroxide solution.

[0021] Further, in step (2), the conditions for the co-current reaction are: the reaction temperature is 25-80℃, the reaction time is 0.5-5h, and the pH value is controlled at 4.0-8.5 during the reaction process.

[0022] Further, in step (2), the aging conditions are: the aging temperature is 25-80℃ and the aging time is 0.5-5h.

[0023] Furthermore, in step (2), the CO2 injection rate is 2 to 25 mL / min relative to the volume of the mixture obtained in step (1) of 1 L.

[0024] Furthermore, in step (2), preferably, CO2 is continuously introduced during both the co-current reaction and the aging process.

[0025] Further, in step (2), the post-processing includes filtration, washing, and drying. The filtration and washing are performed using conventional methods in the art. The drying conditions are: a drying temperature of 25–80°C and a drying time of 6–24 hours.

[0026] Further, in step (3), the calcination conditions are as follows: the calcination temperature is 300–500°C, and the calcination time is 2–8 hours. Preferably, the calcination is performed using 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.

[0027] Further, in step (3), the unformed catalyst is mixed with graphite and then compressed into tablets. The amount of graphite used is 0.1 wt% to 5 wt% based on the weight of the unformed catalyst.

[0028] Furthermore, in step (3), after tableting, there are no special requirements for the shape of the catalyst. Generally, the catalyst is cylindrical with a diameter of 2 to 6 mm and a height of 2 to 5 mm, preferably 3 to 4 mm.

[0029] A third aspect of the present invention provides a catalyst prepared by the above method.

[0030] Furthermore, the lateral compressive strength of the catalyst is 90-120 N / particle, preferably 90-110 N / particle, and the bulk density of the catalyst is 160-195 g / 100 mL, preferably 170-190 g / 100 mL.

[0031] Furthermore, the copper-chromium catalyst comprises CuO and Cr2O3, and the weight content of each component is as follows, based on the weight of the catalyst: CuO is 40-57 wt%, and Cr2O3 is 40-57 wt%.

[0032] Furthermore, the copper-chromium catalyst also includes a forming aid, such as graphite, with the content of the forming aid being 0.1 to 5 wt% based on the weight of the catalyst.

[0033] Furthermore, the copper-chromium catalyst, based on a cylindrical shaped catalyst with a diameter of 3 mm and a height of 3.2 ± 0.2 mm, has a weight of 10 catalyst particles (total weight of 10 catalyst particles) of 0.70–0.90 g, preferably 0.75–0.87 g.

[0034] The fourth aspect of the present invention provides the application of the above-mentioned copper-chromium catalyst in the hydrogenation of dimethyl maleate to prepare 1,4-butanediol.

[0035] Furthermore, the copper-chromium catalyst is first reduced with hydrogen before use, under the following conditions: hydrogen pressure of 0-1 MPa, reduction temperature of 220-300℃, and reduction time of 6-24 h.

[0036] Furthermore, the reaction conditions for using the copper-chromium catalyst in the hydrogenation of dimethyl maleate to prepare 1,4-butanediol are: reaction temperature 150–300 °C; feed volume hourly space velocity 0.1–2.0 h⁻¹. -1 H2 / ester molar ratio (100-300): 1; reaction pressure 1-10 MPa.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1. The present invention uses polyethylene glycol and carbon dioxide bubbling as a soft template for preparing a copper-chromium catalyst, which is removed during the catalyst calcination process. The method is simple and requires no subsequent processing steps.

[0039] 2. The catalyst prepared by this invention has a low packing density and can still maintain a high lateral pressure strength even with a low weight of 10 particles.

[0040] 3. The catalyst prepared by this invention has good mechanical strength and bulk density, and exhibits high conversion rate and selectivity in the hydrogenation reaction of dimethyl maleate to 1,4-butanediol. Detailed Implementation

[0041] 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.

[0042] In this invention, the weight of 10 catalyst particles was determined using a Mettler Toledo Instruments (Shanghai) Co., Ltd. AL204 electronic balance. Ten particles were selected from the test sample, and their total weight was measured. The average of three measurements was taken as the weight of 10 catalyst particles. The mechanical strength was determined using a DLⅢ intelligent particle strength tester from Dalian Chemical Research and Design Institute to measure the radial crushing force of the molded catalyst. The instrument has a range of 300N and an accuracy of 0.1N. Ten particles were selected from the test sample, and their radial crushing force was measured. The maximum and minimum values ​​were discarded, and the average of three measurements was taken as the lateral compressive mechanical strength of the catalyst. The bulk density was determined using a Mettler Toledo Instruments (Shanghai) Co., Ltd. AL204 electronic balance and a 250mL graduated cylinder. The catalyst dimensions were measured using vernier calipers. Elemental composition and content were analyzed using a PANalytical Axios (Netherlands) X-ray fluorescence spectrometer.

[0043] Example 1

[0044] (1) Prepare a metal salt solution by mixing copper nitrate and chromic anhydride with water. The concentration of copper ions in the solution is 1.0 mol / L, and the concentration of chromium ions is 1.0 mol / L. Add polyethylene glycol (molecular weight 4000) to the above metal salt solution and control the concentration of polyethylene glycol in the resulting mixture to be 0.2 g / mL.

[0045] (2) The precipitant solution was a 10wt% ammonia solution. An acid-base co-precipitation process was used. 4L of the mixture obtained in step (1) was added to the precipitant solution in a co-current manner. The reaction temperature was controlled at 30℃, the reaction pH was 7.0, and the reaction time was 2h. After the reaction, the mixture was aged at 30℃ for 2h. During the reaction and aging process, CO2 (50mL / min) was introduced into the system. After aging, the mixture was filtered and washed 6 times with deionized water, then dried in a 60℃ oven for 12h to collect the catalyst precursor.

[0046] (3) The catalyst precursor obtained in step (2) is placed in a muffle furnace for calcination. The calcination conditions are as follows: the heating rate to the calcination temperature is 5℃ / min, the calcination temperature is 400℃, the calcination time is 4h, and the calcination atmosphere is air, to obtain an unformed catalyst.

[0047] (4) Mix the unformed catalyst with graphite evenly, and automatically form it into cylindrical particles with a diameter of 3 mm and a height of 3.23 mm by a tablet press, which is catalyst A1. The content of CuO is 48.8 wt%, the content of Cr2O3 is 48.3 wt%, the content of graphite is 2%, and the rest are impurities. The properties of catalyst A1 are shown in Table 1.

[0048] The catalyst prepared in this invention is used for the hydrogenation of dimethyl maleate to 1,4-butanediol. Molded catalyst A1 is selected as the catalyst. Before the reaction, the catalyst is reduced with hydrogen under the following conditions: hydrogen pressure 0.1 MPa, reduction temperature 270℃, and reduction time 12 h. After reduction, the reaction is carried out under the following conditions: reaction temperature 190℃; feed hourly space velocity 0.25 h⁻¹. -1 The H2 / ester molar ratio was 200:1; the reaction pressure was 6.0 MPa; after 200 h of operation, the conversion rate of dimethyl maleate was 99.90%; and the yield of 1,4-butanediol was 88.82%.

[0049] Example 2

[0050] (1) Prepare a metal salt solution by mixing copper nitrate and chromic anhydride with water. The concentration of copper ions in the solution is 1.0 mol / L, and the concentration of chromium ions is 1.0 mol / L. Add polyethylene glycol (molecular weight 4000) to the above metal salt solution and control the concentration of polyethylene glycol in the resulting mixture to be 0.2 g / mL.

[0051] (2) The precipitant solution was a 10wt% ammonia solution. An acid-base co-precipitation process was used. 4L of the mixture obtained in step (1) was added to the precipitant solution in a co-current manner. The reaction temperature was controlled at 30℃, the reaction pH was 7.0, and the reaction time was 2h. CO2 (50mL / min) was introduced into the system during the reaction. After the reaction, the mixture was aged at 30℃ for 2h. After aging, the mixture was filtered and separated, washed 6 times with deionized water, and dried in an oven at 60℃ for 12h to collect the catalyst precursor.

[0052] (3) The catalyst precursor obtained in step (2) is placed in a muffle furnace for calcination. The calcination conditions are as follows: the heating rate to the calcination temperature is 5℃ / min, the calcination temperature is 400℃, the calcination time is 4h, and the calcination atmosphere is air, to obtain an unformed catalyst.

[0053] (4) Mix the unformed catalyst with graphite evenly, and automatically form it into cylindrical particles with a diameter of 3 mm and a height of 3.29 mm by a tablet press, which is catalyst A2. The content of CuO is 48.8 wt%, the content of Cr2O3 is 48.3 wt%, the content of graphite is 2%, and the rest are impurities. The properties of catalyst A2 are shown in Table 1.

[0054] The catalyst reduction and reaction conditions were the same as in Example 1. After 200 hours of operation, the conversion rate of dimethyl maleate was 99.87% and the yield of 1,4-butanediol was 87.58%.

[0055] Example 3

[0056] (1) Prepare a metal salt solution by mixing copper nitrate and chromic anhydride with water. The concentration of copper ions in the solution is 1.0 mol / L, and the concentration of chromium ions is 1.0 mol / L. Add polyethylene glycol (molecular weight 6000) to the above metal salt solution and control the concentration of polyethylene glycol in the resulting mixture to be 0.1 g / mL.

[0057] (2) The precipitant solution was a 10wt% ammonia solution. An acid-base co-precipitation process was used. 4L of the mixture obtained in step (1) was added to the precipitant solution in a co-current manner. The reaction temperature was controlled at 40℃, the reaction pH was 7.5, and the reaction time was 2.0h. After the reaction, the mixture was aged at 30℃ for 2h. During the reaction and aging process, CO2 (50mL / min) was introduced into the system. After aging, the mixture was filtered and washed 6 times with deionized water, then dried in a 60℃ oven for 12h to collect the catalyst precursor.

[0058] (3) The catalyst precursor obtained in step (2) is placed in a muffle furnace for calcination. The calcination conditions are as follows: the heating rate to the calcination temperature is 10℃ / min, the calcination temperature is 400℃, the calcination time is 4h, and the calcination atmosphere is air, to obtain an unformed catalyst.

[0059] (4) Mix the unformed catalyst with graphite evenly, and automatically form it into cylindrical particles with a diameter of 3 mm and a height of 3.36 mm by a tablet press, which is catalyst A3. The content of CuO is 49.2 wt%, the content of Cr2O3 is 48.5 wt%, the content of graphite is 1%, and the rest are impurities; the properties of catalyst A3 are shown in Table 1.

[0060] The catalyst reduction and reaction conditions were the same as in Example 1. After 200 hours of operation, the conversion rate of dimethyl maleate was 99.83% and the yield of 1,4-butanediol was 88.30%.

[0061] Example 4

[0062] (1) Prepare a metal salt solution by mixing copper nitrate and chromic anhydride with water. The concentration of copper ions in the solution is 1.0 mol / L, and the concentration of chromium ions is 1.0 mol / L. Add polyethylene glycol (molecular weight 4000) to the above metal salt solution and control the concentration of polyethylene glycol in the resulting mixture to be 0.2 g / mL.

[0063] (2) The precipitant solution was a 10wt% ammonia solution. An acid-base co-precipitation process was used. 4L of the mixture obtained in step (1) was added to the precipitant solution in a co-current manner. The reaction temperature was controlled at 30℃, the reaction pH was 7.0, and the reaction time was 2h. After the reaction, the mixture was aged at 30℃ for 2h. During the aging process, CO2 (50mL / min) was introduced into the system. After aging, the mixture was filtered and washed 6 times with deionized water. It was then dried in a 60℃ oven for 12h to collect the catalyst precursor.

[0064] (3) The catalyst precursor obtained in step (2) is placed in a muffle furnace for calcination. The calcination conditions are as follows: the heating rate to the calcination temperature is 5℃ / min, the calcination temperature is 400℃, the calcination time is 4h, and the calcination atmosphere is air, to obtain an unformed catalyst.

[0065] (4) The unformed catalyst is mixed evenly with graphite and automatically formed into cylindrical particles with a diameter of 3 mm and a height of 3.15 mm by a tablet press, which is catalyst A4. The content of CuO is 48.8 wt%, the content of Cr2O3 is 48.3 wt%, the content of graphite is 2%, and the rest are impurities. The properties of catalyst A4 are shown in Table 1.

[0066] The catalyst reduction and reaction conditions were the same as in Example 1. After 200 hours of operation, the conversion rate of dimethyl maleate was 99.78% and the yield of 1,4-butanediol was 88.23%.

[0067] Example 5

[0068] (1) Prepare a metal salt solution by mixing copper nitrate and chromic anhydride with water. The concentration of copper ions in the solution is 1.5 mol / L, and the concentration of chromium ions is 1.5 mol / L. Add polyethylene glycol (molecular weight 4000) to the above metal salt solution and control the concentration of polyethylene glycol in the resulting mixture to be 0.2 g / mL.

[0069] (2) The precipitant solution was a 10wt% ammonia solution. An acid-base co-precipitation process was used. 4L of the mixture obtained in step (1) was added to the precipitant solution in a co-current manner. The reaction temperature was controlled at 30℃, the reaction pH was 7.0, and the reaction time was 2h. After the reaction, the mixture was aged at 30℃ for 2h. During the reaction and aging process, CO2 (70mL / min) was introduced into the system. After aging, the mixture was filtered and washed 6 times with deionized water, then dried in a 60℃ oven for 12h to collect the catalyst precursor.

[0070] (3) The catalyst precursor obtained in step (2) is placed in a muffle furnace for calcination. The calcination conditions are as follows: the heating rate to the calcination temperature is 5℃ / min, the calcination temperature is 400℃, the calcination time is 4h, and the calcination atmosphere is air, to obtain an unformed catalyst.

[0071] (4) Mix the unformed catalyst with graphite evenly, and automatically form it into cylindrical particles with a diameter of 3 mm and a height of 3.25 mm by a tablet press, which is catalyst A5. The content of CuO is 49.0 wt%, the content of Cr2O3 is 48.7 wt%, the content of graphite is 1.5%, and the rest are impurities. The properties of catalyst A5 are shown in Table 1.

[0072] The catalyst reduction and reaction conditions were the same as in Example 1. After 200 hours of operation, the conversion rate of dimethyl maleate was 99.95% and the yield of 1,4-butanediol was 88.31%.

[0073] Comparative Example 1

[0074] (1) Prepare a metal salt solution by mixing copper nitrate and chromic anhydride with water. The concentration of copper ions in the solution is 1.0 mol / L and the concentration of chromium ions is 1.0 mol / L.

[0075] (2) The precipitant solution was a 10wt% ammonia solution. An acid-base co-precipitation process was used. 4L of the mixture obtained in step (1) was added to the precipitant solution in a co-current manner. The reaction temperature was controlled at 30℃, the reaction pH was 7.0, and the reaction time was 2.0h. After the reaction, the mixture was aged at 30℃ for 2h. During the reaction and aging process, CO2 (50mL / min) was introduced into the system. After aging, the mixture was filtered and washed 6 times with deionized water, then dried in a 60℃ oven for 12h to collect the catalyst precursor.

[0076] (3) The catalyst precursor obtained in step (2) is placed in a muffle furnace for calcination. The calcination conditions are as follows: the heating rate to the calcination temperature is 5℃ / min, the calcination temperature is 400℃, the calcination time is 4h, and the calcination atmosphere is air, to obtain an unformed catalyst.

[0077] (4) The unformed catalyst is mixed evenly with graphite and automatically formed into cylindrical particles with a diameter of 3 mm and a height of 3.57 mm by a tablet press, which is catalyst B1. The content of CuO is 48.8 wt%, the content of Cr2O3 is 48.3 wt%, the content of graphite is 2%, and the rest are impurities. The properties of catalyst B1 are shown in Table 1.

[0078] The catalyst reduction and reaction conditions were the same as in Example 1. After 200 hours of operation, the conversion rate of dimethyl maleate was 97.10% and the yield of 1,4-butanediol was 82.30%.

[0079] Comparative Example 2

[0080] (1) Prepare a metal salt solution by mixing copper nitrate and chromic anhydride with water. The concentration of copper ions in the solution is 1.0 mol / L, and the concentration of chromium ions is 1.0 mol / L. Add polyethylene glycol (molecular weight 4000) to the above metal salt solution and control the concentration of polyethylene glycol in the resulting mixture to be 0.2 g / mL.

[0081] (2) The precipitant solution is a 10wt% ammonia solution. The acid-base co-precipitation process is adopted. 4L of the mixture obtained in step (1) and the precipitant solution are added in a co-current manner. The reaction temperature is controlled at 30℃, the reaction pH is 7.0, the reaction time is 2h, and after the reaction is completed, it is aged at 30℃ for 2h. After aging, it is filtered and separated and washed with deionized water 6 times. It is dried in an oven at 60℃ for 12h and the catalyst precursor is collected.

[0082] (3) The catalyst precursor obtained in step (2) is placed in a muffle furnace for calcination. The calcination conditions are as follows: the heating rate to the calcination temperature is 5℃ / min, the calcination temperature is 400℃, the calcination time is 4h, and the calcination atmosphere is air, to obtain an unformed catalyst.

[0083] (4) The unformed catalyst is mixed evenly with graphite and automatically formed into cylindrical particles with a diameter of 3 mm and a height of 3.55 mm by a tablet press, which is catalyst B2. The content of CuO is 48.8 wt%, the content of Cr2O3 is 48.3 wt%, the content of graphite is 2%, and the remainder is impurities. The properties of catalyst B2 are shown in Table 1.

[0084] The catalyst reduction and reaction conditions were the same as in Example 1. After 200 hours of operation, the conversion rate of dimethyl maleate was 98.30% and the yield of 1,4-butanediol was 83.40%.

[0085] Table 1. Properties of the catalysts obtained in each example.

[0086]

[0087] Note: The weight of 10 particles refers to the total weight of 10 catalyst particles.

[0088] 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 copper-chromium catalyst, characterized in that, The catalyst has a lateral compressive strength of 90-120 N / particle, preferably 90-110 N / particle, and a bulk density of 160-195 g / 100 mL, preferably 170-190 g / 100 mL.

2. The copper-chromium catalyst according to claim 1, characterized in that, The copper-chromium catalyst comprises CuO and Cr2O3, and the weight content of each component is as follows, based on the weight of the catalyst: CuO 40-57 wt%, Cr2O3 40-57 wt%.

3. The copper-chromium catalyst according to claim 1, characterized in that, The copper-chromium catalyst, based on a cylindrical shaped catalyst with a diameter of 3 mm and a height of 3.2 ± 0.2 mm, has a weight of 0.70–0.90 g for 10 catalyst particles, preferably 0.75–0.87 g.

4. A method for synthesizing a copper-chromium catalyst, characterized in that, include: (1) Mix copper source and chromium source with polyethylene glycol to obtain a mixture; (2) The mixture obtained in step (1) is reacted with a precipitant in a co-current reaction. After the reaction is completed, the mixture is aged and then post-treated to obtain a catalyst precursor. CO2 is continuously introduced during the co-current reaction and / or aging process. (3) The catalyst precursor obtained in step (2) is calcined to obtain an unformed catalyst, which is then pressed into tablets to obtain a copper-chromium catalyst.

5. The method according to claim 4, characterized in that, In step (1), the copper source is a soluble copper salt, preferably one or more of copper nitrate, copper acetate, copper chloride, and copper sulfate; the chromium source is a soluble chromium salt, preferably one or more of chromic anhydride, chromium nitrate, and chromium chloride. And / or, in step (2), the precipitant is one or more of sodium carbonate solution, sodium bicarbonate solution, ammonia water, and sodium hydroxide solution.

6. The method according to claim 4, characterized in that, In step (1), the copper source and chromium source are first mixed with water to obtain a metal salt solution, and then mixed with polyethylene glycol to obtain a mixture; in the metal salt solution containing copper source and chromium source, the concentration of copper ions is 0.05-5 mol / L and the concentration of chromium ions is 0.05-5 mol / L.

7. The method according to claim 4, characterized in that, In step (1), the molecular weight of the polyethylene glycol is 1000 to 10000. And / or, in step (1), the mass concentration of polyethylene glycol in the mixture is 0.05 to 0.4 g / mL, preferably 0.1 to 0.4 g / mL.

8. The method according to claim 4, characterized in that, In step (2), the conditions for the co-current reaction are: reaction temperature of 25-80℃, reaction time of 0.5-5h, and pH value controlled at 4.0-8.5 during the reaction process; And / or, in step (2), the aging conditions are: the aging temperature is 25 to 80°C, and the aging time is 0.5 to 5 hours.

9. The method according to claim 8, characterized in that, In step (2), the CO2 flow rate is 2 to 25 mL / min relative to the volume of the mixture obtained in step (1). Preferably, in step (2), CO2 is continuously introduced during both the co-current reaction and the aging process.

10. The method according to claim 4, characterized in that, In step (2), the post-processing includes filtration, washing and drying; the drying conditions are: the drying temperature is 25-80℃ and the drying time is 6-24h. And / or, in step (3), the calcination conditions are: the calcination temperature is 300-500℃, the calcination time is 2-8h; 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.

11. The method according to claim 4, characterized in that, In step (3), the unformed catalyst is mixed with graphite and then pressed into tablets; the amount of graphite used is 0.1wt% to 5wt% based on the weight of the unformed catalyst.

12. The method according to claim 4 or 11, characterized in that, In step (3), after tableting, the catalyst is cylindrical with a diameter of 2-6 mm and a height of 2-5 mm, preferably 3-4 mm.

13. The use of a copper-chromium catalyst according to any one of claims 1-3 or a copper-chromium catalyst prepared by any one of claims 4-12 in the hydrogenation of dimethyl maleate to 1,4-butanediol.

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