Preparation method of dimethyl terephthalate hydrogenation reduction catalyst and application thereof

Abstract

The application discloses a preparation method of a dimethyl terephthalate hydrogenation catalyst, which comprises the following steps: (1) adding a cerium salt aqueous solution into an alkali solution, and performing a hydrothermal reaction at 110-140 DEG C; after the reaction is completed, drying the solid in the system, and calcining at 400-600 DEG C for 3-8 hours to obtain a nano-structured cerium dioxide carrier; (2) mixing the cerium dioxide carrier with a ruthenium salt aqueous solution, adding an alkali to control the pH value to be 13-14, drying the obtained solid, and calcining at 450-650 DEG C for 3-8 hours to obtain the target catalyst. The application also discloses a method for preparing dimethyl 1,4-cyclohexane dicarboxylate by hydrogenating dimethyl terephthalate by using the catalyst. When the catalyst is used for hydrogenating dimethyl terephthalate, the catalyst exhibits excellent catalytic performance. In addition, the catalyst has good stability in circulation and application, and has a good industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the field of catalyst preparation and application, and particularly relates to a preparation method and application of a dimethyl terephthalate hydrogenation reduction catalyst. Background Art

[0002] Dimethyl 1,4-cyclohexanedicarboxylate (DMCD) is a chemical raw material and intermediate that has attracted much attention both domestically and internationally in recent years. It can not only be used to produce polyester resins, but can also be further hydrogenated to produce 1,4-cyclohexanedimethanol (CHDM), which is widely used in the production of high-performance polyesters and copolyesters, such as PETG, Spectar copolyesters, PCT, and PCTA. The global market demand for DMCD and CHDM continues to grow. However, traditional production technology mainly uses benzene from petroleum cracking as a raw material and requires multiple steps to produce it. Therefore, hydrogenating dimethyl terephthalate (DMT) obtained by alcoholysis of waste polyester PET to produce DMCD, and further hydrogenating DMCD to produce CHDM through ester group hydrogenation, can reduce dependence on fossil resources and have important significance in terms of energy conservation, emission reduction, and environmental protection. This route is currently the industrialized method for producing CHDM.

[0003] Currently, the catalysts used for DMT hydrogenation reactions primarily include Pd-based, Ru-based, and Pd-Ru bimetallic catalysts supported on Al2O3 or carbon, as well as non-precious metal catalysts primarily based on Ni. Pd-based catalysts have high catalytic activity, but require high reaction pressures and temperatures. Furthermore, Pd-based catalysts are expensive, making large-scale use costly. Compared to palladium-based catalysts, Ru-based catalysts offer advantages such as low cost and high catalytic activity at low temperatures and pressures, but in practice, their selectivity is lower than that of palladium-based catalysts. Pd-Ru bimetallic composite catalysts exhibit significantly improved catalytic activity due to the synergistic effect between the metals, offering unique advantages for DMT hydrogenation to DMCD. However, current bimetallic catalysts suffer from high precious metal consumption, a cumbersome preparation process, and high costs, making them difficult to commercialize. Ni-based catalysts are non-precious metal catalysts, inexpensive, and stable. While maintaining high catalytic activity and selectivity, they significantly moderate reaction conditions. However, the low selectivity for DMCD using nickel-based catalysts limits their application in the industrial production of DMT hydrogenation to DMCD. Summary of the Invention

[0004] In response to the problems of low selectivity, high cost, and harsh reaction conditions in traditional DMT hydrogenation reduction catalysts, the present invention provides a ceria-supported ruthenium monometallic catalyst, which is low-cost, easy to prepare, can be recycled multiple times without significant loss of activity. It is applied to the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD). The reaction conditions are mild, the conversion rate and selectivity are high, and it has good industrial prospects.

[0005] A method for preparing a dimethyl terephthalate hydrogenation reduction catalyst comprises the following steps:

[0006] (1) adding a cerium salt aqueous solution dropwise to an alkaline solution, performing a hydrothermal reaction at 110-140° C., drying the solid in the system after the reaction, and calcining at 400-600° C. for 3-8 hours to obtain a nanostructured cerium dioxide support;

[0007] (2) The ceria carrier and the ruthenium salt aqueous solution are mixed, and a base is added to control the pH to 13-14. The obtained solid is dried and calcined at 450-650° C. for 3-8 hours to obtain the target catalyst.

[0008] Furthermore, the cerium salt is selected from one or more of cerium nitrate, cerium acetate, and cerium chloride; and the ruthenium salt is selected from one or both of ruthenium trichloride and ruthenium acetate.

[0009] Furthermore, the alkali may be an aqueous sodium hydroxide solution.

[0010] Furthermore, the nanostructured cerium dioxide carrier is in one or more structures of nanoparticles, nanorods, and nanocubes.

[0011] Furthermore, the temperature of the hydrothermal reaction is 110-135°C, more preferably 110-130°C.

[0012] Furthermore, the hydrothermal reaction time is 3 to 30 hours, more preferably 5 to 30 hours, and even more preferably 10 to 30 hours.

[0013] Furthermore, in step (1), the drying temperature is 80-120°C, more preferably 90-110°C.

[0014] Furthermore, in step (1), the calcination temperature is 450-550° C., the time is 4-6 hours, and the heating rate is 1.5-3° C. / min.

[0015] Furthermore, in step (2), the drying temperature is 80-120°C, more preferably 90-110°C, and the calcination temperature is 500-600°C for 4-6 hours, with a heating rate of 3-8°C / min.

[0016] Furthermore, a method for preparing a dimethyl terephthalate hydrogenation reduction catalyst comprises the following steps:

[0017] (I) Dissolving cerium nitrate hexahydrate in deionized water to obtain solution a, dissolving different masses of sodium hydroxide in deionized water to obtain solution b, adding solution a dropwise to solution b at room temperature with stirring, and transferring the solution to a reactor for hydrothermal reaction. The product is washed, dried, and calcined to obtain three types of cerium dioxide with different nanostructures; II. The three types of cerium dioxide with different nanostructures are added to deionized water, ultrasonicated, added with ruthenium trichloride and stirred, and then added with alkaline solution and stirred. The solution is allowed to stand overnight, and the target catalyst is obtained through washing, filtration, drying, and calcination.

[0018] More specifically, a method for preparing a dimethyl terephthalate hydrogenation reduction catalyst comprises the following steps:

[0019] (I) dissolving a certain amount of cerium nitrate hexahydrate in deionized water to obtain solution a, dissolving a certain amount of sodium hydroxide in deionized water to obtain solution b, adding solution a dropwise to solution b at room temperature and stirring for 1 to 3 hours (e.g., 2 hours), transferring the mixture to a reactor, and hydrothermally reacting the mixture at 110 to 130° C. (e.g., 120° C.) for 10 to 30 hours (e.g., 24 hours), washing the mixture with deionized water and filtering the mixture until the pH value is neutral (e.g., 7), drying the mixture at 90 to 110° C. (e.g., 100° C.) overnight, placing the mixture in a muffle furnace and heating the mixture to 450 to 550° C. (e.g., 500° C.) at a heating rate of 1.5 to 3° C. / min (e.g., 2.5° C. / min) and maintaining the temperature for 4 to 6 hours (e.g., 5 hours) to obtain three different nanostructured cerium dioxide supports: nanoparticles, nanorods, and nanocubes;

[0020] (II) adding a certain amount of three different nanostructured cerium dioxide supports to deionized water and ultrasonicating for 5 to 20 minutes (for example, 10 minutes), adding a certain amount of ruthenium trichloride and stirring for 1 to 3 hours (for example, 2 hours), adding alkali solution to control the pH to 13 to 14, stirring for 1 to 3 hours (for example, 2 hours), standing overnight, washing with distilled water and filtering to a pH of 7, drying at 90 to 110°C (for example, 100°C) overnight, placing in a muffle furnace and heating at a heating rate of 3 to 8°C / min (for example, 5°C / min) to 500 to 600°C (for example, 550°C) and maintaining for 3 to 8 hours (for example, 5 hours) to obtain the target catalyst.

[0021] More specifically, a method for preparing a dimethyl terephthalate hydrogenation reduction catalyst comprises the following steps: (I) dissolving a certain amount of cerium nitrate hexahydrate in deionized water to obtain solution a, dissolving a certain amount of sodium hydroxide in deionized water to obtain solution b, adding solution a dropwise to solution b at room temperature and stirring for 2 hours, transferring the solution to a reactor, and subjecting the solution to a hydrothermal reaction at 120°C for 24 hours. The product is washed with deionized water and filtered to a pH of 7, dried at 100°C overnight, and placed in a muffle furnace and heated to 500°C at a heating rate of 2.5°C / min and maintained at 400°C. 5h, to obtain three different nano-configuration ceria supports of nanoparticles, nanorods and nanocubes; (II) a certain amount of three different nano-configuration ceria supports were added to deionized water and ultrasonicated for 10min, a certain amount of ruthenium trichloride was added and stirred for 2h, alkali solution was added to control the pH to 13-14, and stirred for 2h, and allowed to stand overnight, washed with distilled water and filtered to pH 7, dried at 100℃ overnight, placed in a muffle furnace and heated to 550℃ at a heating rate of 5℃ / min and maintained for 5h to obtain the target catalyst.

[0022] In step (I), the prepared ceria carrier comprises three different nanostructures: nanoparticles, nanorods, and nanocubes.

[0023] Furthermore, the amount of ruthenium trichloride added is determined so that the ruthenium loading in the final catalyst is 0.1% to 5% by weight (calculated based on the mass of the support ceria). The ruthenium loading in the prepared ceria-supported ruthenium monometallic catalyst is 0.1% to 5% by weight (based on the mass of the support ceria).

[0024] A dimethyl terephthalate hydrogenation reduction catalyst is prepared by the preparation method described in any one of the above technical solutions.

[0025] Furthermore, the ruthenium loading is 0.1% to 5% wt, calculated based on the mass of the carrier ceria; further preferably, the ruthenium loading is 1% to 5% wt; and further preferably, the ruthenium loading is 2% to 4% wt.

[0026] A method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation reduction of dimethyl terephthalate, wherein the reduction catalyst used is the catalyst described in any one of the above technical solutions.

[0027] A method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation reduction of dimethyl terephthalate comprises: placing dimethyl terephthalate, a catalyst and a solvent in a high-pressure reactor, and performing hydrogenation reduction in a hydrogen atmosphere to obtain dimethyl 1,4-cyclohexanedicarboxylate.

[0028] Furthermore, specifically, a certain amount of dimethyl terephthalate and a catalyst are added to a high-pressure reactor, an appropriate amount of solvent alcohol is added, a certain pressure of hydrogen is filled in, and the reaction is carried out at a specific temperature for a certain time.

[0029] Furthermore, the reaction temperature of the hydrogenation reduction is 100 to 200°C, preferably 140 to 160°C, and more preferably 150 to 160°C.

[0030] Furthermore, the hydrogen pressure for hydrogenation reduction is 2-8 MPa, preferably 4-6 MPa, and more preferably 5-6 MPa.

[0031] Furthermore, the solvent used in the hydrogenation reduction reaction is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, and the like.

[0032] Furthermore, the hydrogenation reduction reaction time is 0.5 to 6 hours, preferably 1 to 3 hours.

[0033] Furthermore, in the hydrogenation reduction, the amount of catalyst used is 1% to 20% by weight, preferably 5% to 10% by weight (based on the mass ratio of dimethyl terephthalate), calculated based on the mass ratio of dimethyl terephthalate.

[0034] Furthermore, the amount of the solvent used is 1 to 20 w / w, preferably 4 to 10 w / w (based on the mass ratio of dimethyl terephthalate).

[0035] Furthermore, in the hydrogenation reduction reaction, the reaction temperature is 140-160° C.; the hydrogen pressure is 4-6 MPa; the catalyst dosage is 5%-11% wt based on the mass of dimethyl terephthalate; and the ruthenium loading in the catalyst is 1%-5% wt based on the mass of the carrier cerium dioxide.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The catalyst carrier of the present invention is ceria, which is one of the most effective carriers for ruthenium loading, mainly because it has Ce 3+ / Ce 4+ The redox ability, oxygen storage capacity and abundant oxygen vacancies of the surfactant can increase the electron density of the surfactant component ruthenium, which is beneficial to improve the dispersion of the active component ruthenium and promote the adsorption and activation of hydrogen.

[0038] (2) The catalyst of the present invention has good catalytic performance and can be recycled. The DMT conversion rate can reach more than 99%, and the DMCD selectivity can reach more than 99%.

[0039] (3) The catalyst is used for the hydrogenation of DMT to prepare DMCD, which has simple operation, mild reaction conditions and high production efficiency. DETAILED DESCRIPTION

[0040] The present invention will be further explained below with reference to the following examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention, and the scope of protection of the present invention is not limited thereto.

[0041] It is worth noting that after the prepared solid catalyst was centrifuged, the filtrate was diluted with isopropanol and analyzed by gas chromatography, and the conversion rate and selectivity were quantified by normalization method. The chromatographic analysis conditions were as follows: Fuli gas chromatograph (model FuLi9790Ⅱ), capillary column (model RB-5,

[0042] 30m×0.25mm×0.25μm), flame ionization detector (FID); nitrogen as carrier gas, inlet temperature at 280°C, detector temperature at 280°C, and column temperature programmed. The conversion of dimethyl terephthalate and the selectivity for dimethyl 1,4-cyclohexanedicarboxylate were calculated using the following formulas:

[0043]

[0044]

[0045] Example 1:

[0046] Dissolve 6.9663 g of cerium nitrate hexahydrate in 5 mL of deionized water to obtain solution a, and dissolve 19.2233 g of sodium hydroxide in 35 mL of deionized water to obtain solution b. Add solution a dropwise to solution b at room temperature and stir for 2 h. Transfer to a 100 mL reactor and perform hydrothermal reaction at 120 ° C for 24 h. Wash the product with deionized water and filter it until the pH is 7. Dry the sample in a 100 ° C oven overnight, place it in a muffle furnace and heat it to 500 ° C at a heating rate of 2.5 ° C / min and maintain it. 5h to obtain cerium dioxide nanorods; 1.0003g of cerium dioxide nanorods was added to 50mL of deionized water and ultrasonicated for 10min, 0.0620g of ruthenium trichloride was added and stirred for 2h, 1mol / L of sodium hydroxide solution was added to control the pH to 13-14, and stirred for 2h, allowed to stand overnight, washed with distilled water and filtered to pH 7, dried at 100℃ overnight, placed in a muffle furnace and heated to 550℃ at a heating rate of 5℃ / min and maintained for 5h to obtain the target catalyst.

[0047] The target catalyst prepared according to Example 1 above was applied to the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD) under mild conditions. 5.0008g of dimethyl terephthalate, 0.5014g of catalyst, and 20.0000g of isopropyl alcohol were added to a 100mL autoclave, and the mixture was replaced three times with 1.0MPa of hydrogen, then filled with 6.0MPa of hydrogen, and reacted at 160°C for 3h. After the reaction, the catalyst was centrifuged and analyzed by gas chromatography. The calculated conversion of dimethyl terephthalate was 100%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 100%.

[0048] The centrifuged catalyst was thoroughly washed with ethyl acetate and dried for later use. Under the same reaction conditions described above, the stability of DMT hydrogenation to DMCD was investigated, with repeated cycles. In the tenth cycle, the dimethyl terephthalate conversion was 99.93%, and the selectivity for dimethyl 1,4-cyclohexanedicarboxylate was 98.74%.

[0049] Example 2:

[0050] Dissolve 6.9663 g of cerium nitrate hexahydrate in 5 mL of deionized water to obtain solution a, and dissolve 19.2233 g of sodium hydroxide in 35 mL of deionized water to obtain solution b. Add solution a dropwise to solution b at room temperature and stir for 2 h. Transfer to a 100 mL reactor and perform hydrothermal reaction at 120 ° C for 24 h. Wash the product with deionized water and filter it until the pH is 7. Dry the sample in a 100 ° C oven overnight, place it in a muffle furnace and heat it to 500 ° C at a heating rate of 2.5 ° C / min and maintain it. 5h to obtain cerium dioxide nanorods; 1.0003g of cerium dioxide nanorods was added to 50mL of deionized water and ultrasonicated for 10min, 0.0620g of ruthenium trichloride was added and stirred for 2h, 1mol / L of sodium hydroxide solution was added to control the pH to 13-14, and stirred for 2h, allowed to stand overnight, washed with distilled water and filtered to pH 7, dried at 100℃ overnight, placed in a muffle furnace and heated to 550℃ at a heating rate of 5℃ / min and maintained for 5h to obtain the target catalyst.

[0051] The target catalyst prepared according to Example 2 above was applied to the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD) under mild conditions. 1.0023 g of dimethyl terephthalate, 0.1008 g of catalyst, and 4.0100 g of methanol were added to a 25 mL autoclave. The mixture was then filled with 1.0 MPa of hydrogen for three replacements, followed by 5.0 MPa of hydrogen, and the reaction was continued at 160° C. for 1 hour. After the reaction, the catalyst was centrifuged and analyzed by gas chromatography. The calculated conversion of dimethyl terephthalate was 99.02%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.21%.

[0052] Example 3:

[0053] Dissolve 6.9663 g of cerium nitrate hexahydrate in 5 mL of deionized water to obtain solution a, and dissolve 19.2233 g of sodium hydroxide in 35 mL of deionized water to obtain solution b. Add solution a dropwise to solution b at room temperature and stir for 2 h. Transfer to a 100 mL reactor and perform hydrothermal reaction at 120 ° C for 24 h. Wash the product with deionized water and filter it until the pH is 7. Dry the sample in a 100 ° C oven overnight, place it in a muffle furnace and heat it to 500 ° C at a heating rate of 2.5 ° C / min and maintain it. 5h to obtain cerium dioxide nanorods; 1.0003g of cerium dioxide nanorods was added to 50mL of deionized water and ultrasonicated for 10min, 0.0620g of ruthenium trichloride was added and stirred for 2h, 1mol / L of sodium hydroxide solution was added to control the pH to 13-14, and stirred for 2h, allowed to stand overnight, washed with distilled water and filtered to pH 7, dried at 100℃ overnight, placed in a muffle furnace and heated to 550℃ at a heating rate of 5℃ / min and maintained for 5h to obtain the target catalyst.

[0054] The target catalyst prepared according to Example 3 above was applied to the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD) under mild conditions. 1.0012 g of dimethyl terephthalate, 0.1015 g of catalyst, and 4.0100 g of isopropyl alcohol were added to a 25 mL autoclave, and the mixture was replaced three times with 1.0 MPa of hydrogen, then filled with 5.0 MPa of hydrogen, and reacted at 150 ° C for 1 hour. After the reaction, the catalyst was centrifuged and analyzed by gas chromatography. The calculated conversion of dimethyl terephthalate was 99.95%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.44%.

[0055] Example 4:

[0056] Dissolve 6.9619 g of cerium nitrate hexahydrate in 5 mL of deionized water to obtain solution a, and dissolve 1.6028 g of sodium hydroxide in 35 mL of deionized water to obtain solution b. Add solution a dropwise to solution b at room temperature and stir for 2 h. Transfer to a 100 mL reactor and hydrothermally react at 120 ° C for 24 h. Wash the product with deionized water and filter it until the pH is 7. Place the sample in a 100 ° C oven and dry overnight. Place it in a muffle furnace and heat it to 500 ° C at a heating rate of 2.5 ° C / min and maintain it for 5 h. , obtaining cerium dioxide nanoparticles; adding 0.5060 g of cerium dioxide nanoparticles to 25 mL of deionized water and ultrasonicating for 10 minutes, adding 0.0313 g of ruthenium trichloride and stirring for 2 hours, adding 1 mol / L sodium hydroxide solution to control the pH to 13-14, stirring for 2 hours, standing overnight, washing with distilled water and filtering to a pH of 7, drying at 100°C overnight, placing in a muffle furnace and heating to 550°C at a heating rate of 5°C / min and maintaining for 5 hours to obtain the target catalyst.

[0057] The target catalyst prepared according to Example 4 above was applied to the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD) under mild conditions. 1.0030 g of dimethyl terephthalate, 0.1005 g of catalyst, and 4.0167 g of isopropyl alcohol were added to a 25 mL autoclave, and the mixture was replaced three times with 1.0 MPa of hydrogen, then filled with 6.0 MPa of hydrogen, and reacted at 160° C. for 3 h. After the reaction, the catalyst was centrifuged and analyzed by gas chromatography. The calculated conversion of dimethyl terephthalate was 99.35%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.33%.

[0058] Example 5:

[0059] Dissolve 6.9619 g of cerium nitrate hexahydrate in 5 mL of deionized water to obtain solution a, and dissolve 1.6028 g of sodium hydroxide in 35 mL of deionized water to obtain solution b. Add solution a dropwise to solution b at room temperature and stir for 2 h. Transfer to a 100 mL reactor and hydrothermally react at 120 ° C for 24 h. Wash the product with deionized water and filter it until the pH is 7. Place the sample in a 100 ° C oven and dry overnight. Place it in a muffle furnace and heat it to 500 ° C at a heating rate of 2.5 ° C / min and maintain it for 5 h. , obtaining cerium dioxide nanoparticles; adding 0.5060 g of cerium dioxide nanoparticles to 25 mL of deionized water and ultrasonicating for 10 minutes, adding 0.0313 g of ruthenium trichloride and stirring for 2 hours, adding 1 mol / L sodium hydroxide solution to control the pH to 13-14, stirring for 2 hours, standing overnight, washing with distilled water and filtering to a pH of 7, drying at 100°C overnight, placing in a muffle furnace and heating to 550°C at a heating rate of 5°C / min and maintaining for 5 hours to obtain the target catalyst.

[0060] The target catalyst prepared according to Example 5 above was used in the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD) under mild conditions. 1.0033 g of dimethyl terephthalate, 0.1088 g of catalyst, and 4.0033 g of ethanol were added to a 25 mL autoclave. The mixture was then filled with 1.0 MPa of hydrogen for three replacements, followed by 4.0 MPa of hydrogen, and the reaction was carried out at 160° C. for 1 hour. After the reaction, the catalyst was centrifuged and analyzed by gas chromatography. The calculated conversion of dimethyl terephthalate was 100%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.98%.

[0061] Example 6:

[0062] Dissolve 6.9619 g of cerium nitrate hexahydrate in 5 mL of deionized water to obtain solution a, and dissolve 1.6028 g of sodium hydroxide in 35 mL of deionized water to obtain solution b. Add solution a dropwise to solution b at room temperature and stir for 2 h. Transfer to a 100 mL reactor and hydrothermally react at 120 ° C for 24 h. Wash the product with deionized water and filter it until the pH is 7. Place the sample in a 100 ° C oven and dry overnight. Place it in a muffle furnace and heat it to 500 ° C at a heating rate of 2.5 ° C / min and maintain it for 5 h. , obtaining cerium dioxide nanoparticles; adding 0.5060 g of cerium dioxide nanoparticles to 25 mL of deionized water and ultrasonicating for 10 minutes, adding 0.0313 g of ruthenium trichloride and stirring for 2 hours, adding 1 mol / L sodium hydroxide solution to control the pH to 13-14, stirring for 2 hours, standing overnight, washing with distilled water and filtering to a pH of 7, drying at 100°C overnight, placing in a muffle furnace and heating to 550°C at a heating rate of 5°C / min and maintaining for 5 hours to obtain the target catalyst.

[0063] The target catalyst prepared according to Example 6 above was applied to the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD) under mild conditions. 1.0018 g of dimethyl terephthalate, 0.1017 g of catalyst, and 4.0023 g of isopropyl alcohol were added to a 25 mL autoclave, and the mixture was replaced three times with 1.0 MPa of hydrogen, then filled with 4.0 MPa of hydrogen, and reacted at 140° C. for 1 hour. After the reaction, the catalyst was centrifuged and analyzed by gas chromatography. The calculated conversion of dimethyl terephthalate was 99.82%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.51%.

[0064] Example 7:

[0065] Dissolve 6.9624 g of cerium nitrate hexahydrate in 5 mL of deionized water to obtain solution a, and dissolve 38.4044 g of sodium hydroxide in 35 mL of deionized water to obtain solution b. Add solution a dropwise to solution b at room temperature and stir for 2 h. Transfer to a 100 mL reactor and hydrothermally react at 120 ° C for 24 h. Wash the product with deionized water and filter it until the pH is 7. Place the sample in a 100 ° C oven and dry overnight. Place it in a muffle furnace and heat it to 500 ° C at a heating rate of 2.5 ° C / min and maintain it for 5 h. , obtaining cerium dioxide cubic particles; adding 1.0007 g of cerium dioxide cubic particles to 50 mL of deionized water and ultrasonicating for 10 minutes, adding 0.0631 g of ruthenium trichloride and stirring for 2 hours, adding 1 mol / L sodium hydroxide solution to control the pH to 13-14, stirring for 2 hours, standing overnight, washing with distilled water and filtering to a pH of 7, drying at 100°C overnight, placing in a muffle furnace and heating to 550°C at a heating rate of 5°C / min and maintaining for 5 hours to obtain the target catalyst.

[0066] The target catalyst prepared according to Example 7 above was applied to the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD) under mild conditions. 1.0008g of dimethyl terephthalate, 0.1035g of catalyst, and 4.0173g of isopropyl alcohol were added to a 25mL autoclave, and the mixture was replaced three times with 1.0MPa of hydrogen, then filled with 6.0MPa of hydrogen, and reacted at 160°C for 3h. After the reaction, the catalyst was centrifuged and analyzed by gas chromatography. The calculated conversion of dimethyl terephthalate was 99.86%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.60%.

[0067] Example 8:

[0068] Dissolve 6.9624 g of cerium nitrate hexahydrate in 5 mL of deionized water to obtain solution a, and dissolve 38.4044 g of sodium hydroxide in 35 mL of deionized water to obtain solution b. Add solution a dropwise to solution b at room temperature and stir for 2 h. Transfer to a 100 mL reactor and hydrothermally react at 120 ° C for 24 h. Wash the product with deionized water and filter it until the pH is 7. Place the sample in a 100 ° C oven and dry overnight. Place it in a muffle furnace and heat it to 500 ° C at a heating rate of 2.5 ° C / min and maintain it for 5 h. , obtaining cerium dioxide cubic particles; adding 1.0007 g of cerium dioxide cubic particles to 50 mL of deionized water and ultrasonicating for 10 minutes, adding 0.0631 g of ruthenium trichloride and stirring for 2 hours, adding 1 mol / L sodium hydroxide solution to control the pH to 13-14, stirring for 2 hours, standing overnight, washing with distilled water and filtering to a pH of 7, drying at 100°C overnight, placing in a muffle furnace and heating to 550°C at a heating rate of 5°C / min and maintaining for 5 hours to obtain the target catalyst.

[0069] The target catalyst prepared according to Example 8 above was used in the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD) under mild conditions. 1.0014 g of dimethyl terephthalate, 0.1004 g of catalyst, and 4.0000 g of tert-butyl alcohol were added to a 25 mL autoclave, and the mixture was replaced three times with 1.0 MPa of hydrogen, then filled with 4.0 MPa of hydrogen, and reacted at 160° C. for 1 hour. After the reaction, the catalyst was centrifuged and analyzed by gas chromatography. The calculated conversion of dimethyl terephthalate was 99.19%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.61%.

[0070] Example 9:

[0071] Dissolve 6.9624 g of cerium nitrate hexahydrate in 5 mL of deionized water to obtain solution a, and dissolve 38.4044 g of sodium hydroxide in 35 mL of deionized water to obtain solution b. Add solution a dropwise to solution b at room temperature and stir for 2 h. Transfer to a 100 mL reactor and hydrothermally react at 120 ° C for 24 h. Wash the product with deionized water and filter it until the pH is 7. Place the sample in a 100 ° C oven and dry overnight. Place it in a muffle furnace and heat it to 500 ° C at a heating rate of 2.5 ° C / min and maintain it for 5 h. , obtaining cerium dioxide cubic particles; adding 1.0007 g of cerium dioxide cubic particles to 50 mL of deionized water and ultrasonicating for 10 minutes, adding 0.0631 g of ruthenium trichloride and stirring for 2 hours, adding 1 mol / L sodium hydroxide solution to control the pH to 13-14, stirring for 2 hours, standing overnight, washing with distilled water and filtering to a pH of 7, drying at 100°C overnight, placing in a muffle furnace and heating to 550°C at a heating rate of 5°C / min and maintaining for 5 hours to obtain the target catalyst.

[0072] The target catalyst prepared according to Example 9 above was used in the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD) under mild conditions. 1.0044 g of dimethyl terephthalate, 0.1034 g of catalyst, and 4.0099 g of isopropyl alcohol were added to a 25 mL autoclave, and the mixture was replaced three times with 1.0 MPa of hydrogen, then filled with 4.0 MPa of hydrogen, and reacted at 140° C. for 1 hour. After the reaction, the catalyst was centrifuged and analyzed by gas chromatography. The calculated conversion of dimethyl terephthalate was 99.67%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.14%.

Claims

1. A method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation reduction of dimethyl terephthalate, characterized in that: include: Dimethyl terephthalate, a catalyst, and a solvent are placed in a high-pressure reactor and subjected to hydrogenation reduction in a hydrogen atmosphere to obtain dimethyl 1,4-cyclohexanedicarboxylate. The preparation method of the catalyst is as follows: (1) Adding a cerium salt aqueous solution dropwise to an alkaline solution, performing a hydrothermal reaction at 110-140°C, drying the solid in the system after the reaction, and calcining at 400-600°C for 3-8 hours to obtain a nanostructured cerium dioxide carrier; (2) The ceria carrier and the ruthenium salt aqueous solution are mixed, and a base is added to control the pH to 13-14. The obtained solid is dried and calcined at 450-650°C for 3-8 hours to obtain the target catalyst.

2. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation reduction of dimethyl terephthalate according to claim 1, characterized in that: The cerium salt is selected from one or more of cerium nitrate, cerium acetate, and cerium chloride; and the ruthenium salt is selected from one or both of ruthenium trichloride and ruthenium acetate.

3. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation reduction of dimethyl terephthalate according to claim 1, characterized in that: The nanostructured cerium dioxide carrier is in one or more structures of nanoparticles, nanorods, and nanocubes.

4. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation reduction of dimethyl terephthalate according to claim 1, characterized in that Calculated based on the mass of the carrier cerium dioxide, the loading amount of ruthenium is 0.1% to 5%wt.

5. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation reduction of dimethyl terephthalate according to claim 1, characterized in that: The reaction temperature is 100-200° C.; the hydrogen pressure is 2-8 MPa; and the solvent used in the reaction is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tert-butanol.

6. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation reduction of dimethyl terephthalate according to claim 1, characterized in that: Calculated based on the mass of dimethyl terephthalate, the amount of catalyst used is 1% to 20%wt.

7. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate by hydrogenation reduction of dimethyl terephthalate according to claim 1, characterized in that: The reaction temperature is 140-160° C.; the hydrogen pressure is 4-6 MPa; the catalyst dosage is 5%-11%wt based on the mass of dimethyl terephthalate; and the ruthenium loading in the catalyst is 1%-5%wt based on the mass of the carrier cerium dioxide.

Images