Preparation method of dimethyl 1, 4-cyclohexanedicarboxylate

Abstract

The invention belongs to a preparation method of a chemical intermediate, and particularly relates to a preparation method of dimethyl 1, 4-cyclohexanedicarboxylate, which comprises the following steps: carrying out hydrogenation reaction on dimethyl p-toluene in a solvent in a hydrogen atmosphere under the catalysis of a cerium dioxide loaded ruthenium monometal catalyst to obtain the dimethyl 1, 4-cyclohexanedicarboxylate, the invention discloses a method for preparing dimethyl 1, 4-cyclohexanedicarboxylate from dimethyl terephthalate through hydrogenation, which comprises the following steps: under the catalysis of a ruthenium-containing catalyst taking cerium dioxide as a carrier, carrying out hydrogenation reaction on dimethyl terephthalate in a solvent in a hydrogen atmosphere to obtain dimethyl 1, 4-cyclohexanedicarboxylate, and separating the dimethyl 1, 4-cyclohexanedicarboxylate from dimethyl terephthalate to obtain dimethyl 1, 4-cyclohexanedicarboxylate. And after the reaction is completed, the high-purity dimethyl 1, 4-cyclohexanedicarboxylate can be obtained only by filtering out the catalyst and concentrating to remove the solvent, and the operation is simple and convenient.

Description

Technical Field

[0001] The invention belongs to a method for preparing a chemical intermediate, and specifically relates to a method for preparing dimethyl 1,4-cyclohexanedicarboxylate. Background Art

[0002] Dimethyl 1,4-cyclohexanedicarboxylate (DMCD) has received extensive attention at home and abroad in the field of chemical raw materials and intermediates. It not only plays an important role in the production of polyester resins, but can also be converted into 1,4-cyclohexanedimethanol (CHDM) through hydrogenation reaction, and then widely used in the manufacture of high-performance polyesters and copolyesters, such as PETG, Spectar copolyesters, PCT and PCTA. The global demand for DMCD and CHDM is growing steadily. Despite this, traditional DMCD production technology relies on benzene produced by petroleum cracking and requires a series of complex reaction steps. Therefore, the production of DMCD by hydrogenating dimethyl terephthalate (DMT) obtained by alcoholysis of waste polyester PET, and further hydrogenating the DMCD ester group into CHDM, not only reduces dependence on fossil fuels, but also has important significance in energy conservation and environmental protection.

[0003] Currently, the catalysts used in DMT hydrogenation reactions are mainly divided into four categories: palladium-based catalysts, ruthenium-based catalysts, palladium-ruthenium bimetallic composite catalysts, and nickel-based non-precious metal catalysts. Palladium-based catalysts are known for their excellent catalytic activity, but they require higher reaction pressures and temperatures, and due to the high price of palladium, the cost of large-scale application is relatively expensive. Compared with palladium-based catalysts, ruthenium-based catalysts are more cost-effective and can maintain high catalytic activity even at lower temperatures and pressures. However, in practical applications, the selectivity of ruthenium-based catalysts is usually lower than that of palladium-based catalysts. Bimetallic composite catalysts can significantly improve catalytic activity due to the synergistic effect between metals. They have unique advantages for the hydrogenation of DMT to prepare DMCD and show the potential for industrial application. However, the challenges currently faced by these catalysts include high consumption of precious metals, complex preparation processes, and high costs, which limit their industrial application. Nickel-based catalysts, as a non-precious metal catalyst, are favored for their low price and stable chemical properties. Not only do they maintain high catalytic activity and selectivity, but they can also be carried out under milder reaction conditions, which is beneficial for the industrial production of DMT hydrogenation to prepare DMCD. However, the selectivity of nickel-based catalysts in DMCD still needs to be improved.

[0004] In general, traditional DMT hydrogenation catalysts have disadvantages such as low selectivity, high cost, and harsh reaction conditions. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for preparing dimethyl 1,4-cyclohexanedicarboxylate, wherein dimethyl p-toluene dicarboxylate is hydrogenated in a solvent in a hydrogen atmosphere under the catalysis of a ruthenium monometallic catalyst supported by ceria to obtain the dimethyl 1,4-cyclohexanedicarboxylate, and the reaction formula is as follows:

[0006]

[0007] The operation steps are: add a certain amount of dimethyl terephthalate and a catalyst into a high-pressure reactor, add an appropriate amount of solvent, fill it with hydrogen at a certain pressure, and react at a specific temperature for a certain time.

[0008] The solvent used is a C1-C4 alkyl alcohol or an ester catalyst, preferably isopropanol or ethyl acetate.

[0009] Based on the mass ratio of dimethyl terephthalate, the amount of catalyst used is 2wt% to 20wt%, and the amount of solvent used is 5 to 20w / w. Preferably, based on the mass ratio of dimethyl terephthalate, the amount of catalyst used is 5wt% to 10wt%, and the amount of solvent used is 8 to 12w / w.

[0010] The reaction temperature is 100-180°C, the hydrogen pressure is 2Mpa-8MPa, and the reaction time is 0.5h-6h. Preferably, the reaction temperature is 140-160°C, the hydrogen pressure is 4Mpa-6MPa, and the reaction time is 2h-4h.

[0011] The loading amount of ruthenium in the cerium dioxide-supported ruthenium monometallic catalyst is 0.1% to 5wt%, and the carrier cerium dioxide comprises three different nano-configurations: nano-particles, nano-rods and nano-cubes.

[0012] The present invention further provides a cerium dioxide-supported ruthenium monometallic catalyst and a preparation method thereof, which is first applied to the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD), showing excellent catalytic performance, and after multiple cycles of application, the catalytic performance does not change significantly.

[0013] A cerium dioxide-supported ruthenium monometallic catalyst, wherein the ruthenium loading in the cerium dioxide-supported ruthenium monometallic catalyst is 0.1% to 5wt%, and the carrier cerium dioxide comprises three different nano-configurations of nano-particles, nano-rods and nano-cubes.

[0014] The preparation method of the cerium dioxide-supported ruthenium monometallic catalyst described in the present invention is as follows: (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 into solution b at room temperature and stirring for 2 hours, transferring to a reactor, hydrothermally reacting at 120°C for 24 hours, washing the product with deionized water and filtering it to a pH of 7, drying at 100°C overnight, placing it in a muffle furnace and heating it to 500°C at a heating rate of 2.5°C / min and maintaining it for 5 hours, thereby obtaining three different nano-configurations of cerium dioxide carriers, namely nanoparticles, nanorods and nanocubes; (II) dissolving a certain amount of ruthenium trichloride in deionized water, impregnating it into three different nano-configurations of cerium dioxide carriers by an equal volume impregnation method, stirring for 4 hours, ultrasonicating for 30 minutes, drying at 100°C overnight, placing it in a muffle furnace and heating it to 550°C at a heating rate of 5°C / min and maintaining it for 5 hours, thereby obtaining the target catalyst;

[0015] The carrier cerium dioxide in the above method comprises three different nano configurations: nano particles, nano rods and nano cubes.

[0016] The loading amount of ruthenium in the ceria-supported ruthenium monometallic catalyst prepared by the above method (relative to the carrier) is 0.1wt% to 5wt%.

[0017] The cerium oxide-supported ruthenium monometallic catalyst prepared by the above preparation method is applied to the reaction of hydrogenating dimethyl terephthalate (DMT) to prepare dimethyl 1,4-cyclohexanedicarboxylate (DMCD), and the specific reaction conditions are: adding a certain amount of dimethyl terephthalate and catalyst to a high-pressure reactor, adding an appropriate amount of isopropanol or ethyl acetate as a solvent, charging a certain pressure of hydrogen, and reacting at a specific temperature for a certain time. After the reaction is completed, the catalyst is separated by centrifugation, and the reaction liquid is quantitatively analyzed by gas chromatography and area normalization method.

[0018] The above reaction temperature is 120-180°C, the reaction pressure is 2-8MPa, and the reaction time is

[0019] 0.5~5h.

[0020] The catalyst dosage in the above method is 2wt% to 20wt%, preferably 5wt% to 10wt%.

[0021] The amount of solvent used in the above method is 5 to 20 w / w, preferably 8 to 12 w / w.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (a) The catalyst carrier of the present invention is ceria, which is an excellent carrier for loading ruthenium, mainly because it has the redox ability of Ce3+ / Ce4+, oxygen storage capacity and abundant oxygen vacancies, which can increase the electron density of the surface active component ruthenium, which is beneficial to improve the dispersibility of the active component ruthenium, promote the adsorption and activation of hydrogen, have a synergistic effect on ruthenium catalytic hydrogenation, and improve the reaction selectivity.

[0024] (b) The catalyst preparation process of the present invention is simple, the cycle is short, the catalytic performance is good, and it is easy to prepare in large quantities. Under optimal reaction conditions, the DMT conversion rate can reach more than 99%, and the DMCD selectivity can reach about 99%.

[0025] (c) The catalyst is used for hydrogenation of DMT to prepare DMCD. The reaction conditions are mild. After the reaction is completed, it is only necessary to simply filter out the catalyst and concentrate to remove the solvent to obtain a high-purity product. The operation is simple.

[0026] The invention discloses a preparation method of dimethyl terephthalate by hydrogenating dimethyl terephthalate to prepare dimethyl 1,4-cyclohexanedicarboxylate. The method comprises the following steps: under the catalysis of a ruthenium-containing catalyst with ceria as a carrier, dimethyl terephthalate undergoes a hydrogenation reaction in a solvent in a hydrogen atmosphere, after the reaction is complete, only the catalyst needs to be filtered out, and the solvent needs to be concentrated to obtain high-purity dimethyl 1,4-cyclohexanedicarboxylate, and the operation is simple.

[0027] The present invention prepares three different nano-configurations of cerium dioxide, namely nanoparticles, nanorods and nanocubes, as carriers, and adopts an equal volume impregnation method to prepare a single metal ruthenium catalyst with a loading of 0.1wt% to 5wt%. Due to the redox ability, oxygen storage capacity and abundant oxygen vacancies of Ce3+ / Ce4+, the electron density of the surface active component ruthenium can be increased, which is beneficial to improving the dispersibility of the active component ruthenium, promoting the adsorption and activation of hydrogen, and having a synergistic effect with metal ruthenium on catalytic hydrogenation, showing excellent catalytic performance. The present invention uses the catalyst for the first time in the reaction of hydrogenating dimethyl terephthalate to prepare dimethyl 1,4-cyclohexanedicarboxylate. The conversion rate and selectivity under optimal conditions are both above 99%, and the post-treatment is simple. The catalyst can be recycled and applied, has a long service life, and has no obvious deactivation phenomenon after repeated application, and has good prospects for industrial production. DETAILED DESCRIPTION

[0028] The present invention will be further explained below in conjunction with 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.

[0029] It is worth noting that after the prepared solid catalyst is centrifuged, the filtrate is diluted with isopropanol, and the gas chromatography is used for analysis, and the conversion rate and selectivity are quantified by normalization method. The chromatographic analysis conditions are as follows: Fuli gas chromatograph (model FuLi9790Ⅱ), capillary column (model RB-5, 30m×0.25mm×0.25μm), hydrogen flame ionization detector (FID); nitrogen as carrier gas, injection port at 280℃, detector at 280℃, and chromatographic column using programmed temperature rise. Among them, the conversion rate of dimethyl terephthalate and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate are calculated by the following formula:

[0030]

[0031] Embodiment 1:

[0032] 6.9674 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution a, 19.2081 g of sodium hydroxide was dissolved in 35 mL of deionized water to obtain solution b, solution a was added dropwise to solution b at room temperature and stirred for 2 h, then transferred to a 100 mL reactor, subjected to hydrothermal reaction at 120 ° C for 24 h, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100 ° C oven and dried overnight, placed in a muffle furnace and heated to 500 ° C at a heating rate of 2.5 ° C / min and maintained for 5 h to obtain cerium dioxide nanorods; 0.1063 g of ruthenium trichloride was dissolved in 20 mL of deionized water, impregnated into 0.5000 g of cerium dioxide nanorods by an equal volume impregnation method, stirred for 4 h, ultrasonicated for 30 min, dried at 100 ° C overnight, placed in a muffle furnace and heated to 550 ° C at a heating rate of 5 ° C / min and maintained for 5 h to obtain the target catalyst.

[0033] The target catalyst prepared according to the above Example 1 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0029g of dimethyl terephthalate, 0.1005g of catalyst, and 4.0000g of isopropanol were added to a 25mL autoclave, 1.0MPa of hydrogen was charged for replacement three times, and then 5.0MPa of hydrogen was charged, and the reaction was carried out at 160°C for 2h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate was calculated to be 99.86% and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.44%.

[0034] Embodiment 2:

[0035] 6.9674 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution a, 19.2081 g of sodium hydroxide was dissolved in 35 mL of deionized water to obtain solution b, solution a was added dropwise to solution b at room temperature and stirred for 2 h, then transferred to a 100 mL reactor, subjected to hydrothermal reaction at 120 ° C for 24 h, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100 ° C oven and dried overnight, placed in a muffle furnace and heated to 500 ° C at a heating rate of 2.5 ° C / min and maintained for 5 h to obtain cerium dioxide nanorods; 0.1063 g of ruthenium trichloride was dissolved in 20 mL of deionized water, impregnated into 0.5000 g of cerium dioxide nanorods by an equal volume impregnation method, stirred for 4 h, ultrasonicated for 30 min, dried at 100 ° C overnight, placed in a muffle furnace and heated to 550 ° C at a heating rate of 5 ° C / min and maintained for 5 h to obtain the target catalyst.

[0036] The target catalyst prepared according to the above embodiment 2 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0069g dimethyl terephthalate, 0.1018g catalyst, and 4.0000g isopropanol were added to a 25mL autoclave, 1.0MPa hydrogen was charged for replacement three times, and then 5.0MPa hydrogen was charged, and the reaction was carried out at 150°C for 2h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate was calculated to be 100% and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.96%.

[0037] Embodiment 3:

[0038] 6.9674 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution a, 19.2081 g of sodium hydroxide was dissolved in 35 mL of deionized water to obtain solution b, solution a was added dropwise to solution b at room temperature and stirred for 2 h, then transferred to a 100 mL reactor, subjected to hydrothermal reaction at 120 ° C for 24 h, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100 ° C oven and dried overnight, placed in a muffle furnace and heated to 500 ° C at a heating rate of 2.5 ° C / min and maintained for 5 h to obtain cerium dioxide nanorods; 0.0409 g of ruthenium trichloride was dissolved in 20 mL of deionized water, impregnated into 0.6014 g of cerium dioxide nanorods by an equal volume impregnation method, stirred for 4 h, ultrasonicated for 30 min, dried at 100 ° C overnight, placed in a muffle furnace and heated to 550 ° C at a heating rate of 5 ° C / min and maintained for 5 h to obtain the target catalyst.

[0039] The target catalyst prepared according to the above Example 3 is applied to the reaction of preparing 1,4-cyclohexanedicarboxylic acid dimethyl ester (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0038g of dimethyl terephthalate, 0.1007g of catalyst, and 4.0051g of isopropanol were added to a 25mL autoclave, and 1.0MPa of hydrogen was charged for replacement three times, and then 5.0MPa of hydrogen was charged, and the reaction was carried out at 160°C for 1h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate were calculated to be 95.41%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.24%.

[0040] Embodiment 4:

[0041] 6.9674 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution a, 19.2081 g of sodium hydroxide was dissolved in 35 mL of deionized water to obtain solution b, solution a was added dropwise to solution b at room temperature and stirred for 2 h, then transferred to a 100 mL reactor, subjected to hydrothermal reaction at 120 ° C for 24 h, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100 ° C oven and dried overnight, placed in a muffle furnace and heated to 500 ° C at a heating rate of 2.5 ° C / min and maintained for 5 h to obtain cerium dioxide nanorods; 0.0409 g of ruthenium trichloride was dissolved in 20 mL of deionized water, impregnated into 0.6014 g of cerium dioxide nanorods by an equal volume impregnation method, stirred for 4 h, ultrasonicated for 30 min, dried at 100 ° C overnight, placed in a muffle furnace and heated to 550 ° C at a heating rate of 5 ° C / min and maintained for 5 h to obtain the target catalyst.

[0042] The target catalyst prepared according to the above-mentioned Example 4 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0033g of dimethyl terephthalate, 0.1014g of catalyst, and 4.0015g of isopropanol were added to a 25mL autoclave, and 1.0MPa of hydrogen was charged for replacement three times, and then 6.0MPa of hydrogen was charged, and the reaction was carried out at 160°C for 2h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate were calculated to be 99.59%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.10%.

[0043] Embodiment 5:

[0044] 6.9624 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution a, 1.6143 g of sodium hydroxide was dissolved in 35 mL of deionized water to obtain solution b, solution a was added dropwise to solution b at room temperature and stirred for 2 h, then transferred to a 100 mL reactor, subjected to hydrothermal reaction at 120 ° C for 24 h, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100 ° C oven and dried overnight, placed in a muffle furnace and heated to 500 ° C at a heating rate of 2.5 ° C / min and maintained for 5 h to obtain cerium dioxide nanoparticles; 0.1080 g of ruthenium trichloride was dissolved in 20 mL of deionized water, impregnated into 0.5083 g of cerium dioxide nanoparticles by an equal volume impregnation method, stirred for 4 h, ultrasonicated for 30 min, dried at 100 ° C overnight, placed in a muffle furnace and heated to 550 ° C at a heating rate of 5 ° C / min and maintained for 5 h to obtain the target catalyst.

[0045] The target catalyst prepared according to the above-mentioned Example 5 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0011g dimethyl terephthalate, 0.1003g catalyst, and 4.0008g isopropanol were added to a 25mL autoclave, 1.0MPa hydrogen was charged for replacement three times, and then 4.0MPa hydrogen was charged, and the reaction was carried out at 160°C for 2h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate was calculated to be 99.68% and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.07%.

[0046] Embodiment 6:

[0047] 6.9624 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution a, 1.6143 g of sodium hydroxide was dissolved in 35 mL of deionized water to obtain solution b, solution a was added dropwise to solution b at room temperature and stirred for 2 h, then transferred to a 100 mL reactor, subjected to hydrothermal reaction at 120 ° C for 24 h, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100 ° C oven and dried overnight, placed in a muffle furnace and heated to 500 ° C at a heating rate of 2.5 ° C / min and maintained for 5 h to obtain cerium dioxide nanoparticles; 0.1080 g of ruthenium trichloride was dissolved in 20 mL of deionized water, impregnated into 0.5083 g of cerium dioxide nanoparticles by an equal volume impregnation method, stirred for 4 h, ultrasonicated for 30 min, dried at 100 ° C overnight, placed in a muffle furnace and heated to 550 ° C at a heating rate of 5 ° C / min and maintained for 5 h to obtain the target catalyst.

[0048] The target catalyst prepared according to the above-mentioned Example 6 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0017g dimethyl terephthalate, 0.1003g catalyst, and 4.0010g isopropanol were added to a 25mL autoclave, 1.0MPa hydrogen was charged for replacement three times, and then 4.0MPa hydrogen was charged, and the reaction was carried out at 140°C for 2h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate were calculated to be 98.83%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 98.26%.

[0049] Embodiment 7:

[0050] 6.9624 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution a, and 1.6143 g of sodium hydroxide was dissolved in 35 mL of deionized water to obtain solution b. Solution a was added dropwise to solution b at room temperature and stirred for 2 hours, then transferred to a 100 mL reactor, subjected to hydrothermal reaction at 120° C. for 24 hours, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100° C. oven and dried overnight, placed in a muffle furnace and heated to 500° C. at a heating rate of 2.5° C. / min and maintained for 5 hours to obtain cerium dioxide nanoparticles; 0.0450 g of ruthenium trichloride was dissolved in 20 mL of deionized water, impregnated into 0.6010 g of cerium dioxide nanoparticles by an equal volume impregnation method, stirred for 4 hours, ultrasonicated for 30 minutes, dried at 100° C. overnight, placed in a muffle furnace and heated to 550° C. at a heating rate of 5° C. / min and maintained for 5 hours to obtain the target catalyst.

[0051] The target catalyst prepared according to the above-mentioned Example 7 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0045g of dimethyl terephthalate, 0.1054g of catalyst, and 4.0020g of isopropanol were added to a 25mL autoclave, and 1.0MPa of hydrogen was charged for replacement three times, and then 6.0MPa of hydrogen was charged, and the reaction was carried out at 160°C for 2h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate was calculated to be 99.79% and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 97.22%.

[0052] Embodiment 8:

[0053] 6.9624 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water to obtain solution a, and 1.6143 g of sodium hydroxide was dissolved in 35 mL of deionized water to obtain solution b. Solution a was added dropwise to solution b at room temperature and stirred for 2 hours, then transferred to a 100 mL reactor, subjected to hydrothermal reaction at 120° C. for 24 hours, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100° C. oven and dried overnight, placed in a muffle furnace and heated to 500° C. at a heating rate of 2.5° C. / min and maintained for 5 hours to obtain cerium dioxide nanoparticles; 0.0450 g of ruthenium trichloride was dissolved in 20 mL of deionized water, impregnated into 0.6010 g of cerium dioxide nanoparticles by an equal volume impregnation method, stirred for 4 hours, ultrasonicated for 30 minutes, dried at 100° C. overnight, placed in a muffle furnace and heated to 550° C. at a heating rate of 5° C. / min and maintained for 5 hours to obtain the target catalyst.

[0054] The target catalyst prepared according to the above-mentioned Example 8 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0029g dimethyl terephthalate, 0.1021g catalyst, and 4.0015g isopropanol were added to a 25mL autoclave, 1.0MPa hydrogen was charged for replacement three times, and then 6.0MPa hydrogen was charged, and the reaction was carried out at 160°C for 2h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate was calculated to be 99.27% ​​and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 98.24%.

[0055] Embodiment 9:

[0056] 6.9673g of cerium nitrate hexahydrate was dissolved in 5mL of deionized water to obtain solution a, 38.4024g of sodium hydroxide was dissolved in 35mL of deionized water to obtain solution b, solution a was added dropwise to solution b at room temperature and stirred for 2h, transferred to a 100mL reactor, hydrothermally reacted at 120°C for 24h, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100°C oven and dried overnight, placed in a muffle furnace and heated to 500°C at a heating rate of 2.5°C / min and maintained for 5h to obtain cerium dioxide nanocubes; 0.2149g of ruthenium trichloride was dissolved in 20mL of deionized water, impregnated into 1.0003g of cerium dioxide nanocubes by an equal volume impregnation method, stirred for 4h, ultrasonicated for 30min, dried at 100°C overnight, placed in a muffle furnace and heated to 550°C at a heating rate of 5°C / min and maintained for 5h to obtain the target catalyst.

[0057] The target catalyst prepared according to the above Example 9 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0006g dimethyl terephthalate, 0.1004g catalyst, and 4.0099g isopropanol were added to a 25mL autoclave, 1.0MPa hydrogen was charged for replacement three times, and then 4.0MPa hydrogen was charged, and the reaction was carried out at 160°C for 2h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate were calculated to be 99.53%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.83%.

[0058] Embodiment 10:

[0059] 6.9673g of cerium nitrate hexahydrate was dissolved in 5mL of deionized water to obtain solution a, 38.4024g of sodium hydroxide was dissolved in 35mL of deionized water to obtain solution b, solution a was added dropwise to solution b at room temperature and stirred for 2h, transferred to a 100mL reactor, hydrothermally reacted at 120°C for 24h, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100°C oven and dried overnight, placed in a muffle furnace and heated to 500°C at a heating rate of 2.5°C / min and maintained for 5h to obtain cerium dioxide nanocubes; 0.2149g of ruthenium trichloride was dissolved in 20mL of deionized water, impregnated into 1.0003g of cerium dioxide nanocubes by an equal volume impregnation method, stirred for 4h, ultrasonicated for 30min, dried at 100°C overnight, placed in a muffle furnace and heated to 550°C at a heating rate of 5°C / min and maintained for 5h to obtain the target catalyst.

[0060] The target catalyst prepared according to the above embodiment 10 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0079g dimethyl terephthalate, 0.1048g catalyst, and 4.0018g isopropanol were added to a 25mL autoclave, 1.0MPa hydrogen was charged for replacement three times, and then 4.0MPa hydrogen was charged, and the reaction was carried out at 140°C for 2h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate was calculated to be 99.96% and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 98.31%.

[0061] Embodiment 11:

[0062] 6.9673g of cerium nitrate hexahydrate was dissolved in 5mL of deionized water to obtain solution a, 38.4024g of sodium hydroxide was dissolved in 35mL of deionized water to obtain solution b, a was added dropwise to b at room temperature and stirred for 2h, transferred to a 100mL reactor, hydrothermally reacted at 120°C for 24h, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100°C oven and dried overnight, placed in a muffle furnace and heated to 500°C at a heating rate of 2.5°C / min and maintained for 5h to obtain cerium dioxide nanocubes; 0.0439g of ruthenium trichloride was dissolved in 20mL of deionized water, impregnated into 0.6018g of cerium dioxide nanocubes by an equal volume impregnation method, stirred for 4h, ultrasonicated for 30min, dried at 100°C overnight, placed in a muffle furnace and heated to 500°C at a heating rate of 5°C / min and maintained for 5h to obtain the target catalyst.

[0063] The target catalyst prepared according to the above-mentioned Example 11 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0012g of dimethyl terephthalate, 0.1011g of catalyst, and 4.0010g of isopropanol were added to a 25mL autoclave, and 1.0MPa of hydrogen was charged for replacement three times, and then 4.0MPa of hydrogen was charged, and the reaction was carried out at 160°C for 2h. After the reaction was completed, the catalyst was separated by centrifugation, and the gas chromatography detection analysis was performed, and the conversion rate of dimethyl terephthalate was calculated to be 99.44%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 98.38%.

[0064] Embodiment 12:

[0065] 6.9673g of cerium nitrate hexahydrate was dissolved in 5mL of deionized water to obtain solution a, 38.4024g of sodium hydroxide was dissolved in 35mL of deionized water to obtain solution b, a was added dropwise to b at room temperature and stirred for 2h, transferred to a 100mL reactor, hydrothermally reacted at 120°C for 24h, the product was washed with deionized water and filtered to a pH of 7, the sample was placed in a 100°C oven and dried overnight, placed in a muffle furnace and heated to 500°C at a heating rate of 2.5°C / min and maintained for 5h to obtain cerium dioxide nanocubes; 0.0439g of ruthenium trichloride was dissolved in 20mL of deionized water, impregnated into 0.6018g of cerium dioxide nanocubes by an equal volume impregnation method, stirred for 4h, ultrasonicated for 30min, dried at 100°C overnight, placed in a muffle furnace and heated to 550°C at a heating rate of 5°C / min and maintained for 5h to obtain the target catalyst.

[0066] The target catalyst prepared according to the above embodiment 12 is applied to the reaction of preparing dimethyl terephthalate (DMCD) by hydrogenation of dimethyl terephthalate (DMT) under mild conditions. 1.0039g of dimethyl terephthalate, 0.1005g of catalyst, and 4.0079g of isopropanol were added to a 25mL autoclave, and 1.0MPa of hydrogen was charged for replacement three times, and then 6.0MPa of hydrogen was charged, and the reaction was carried out at 160°C for 2h. After the reaction, the catalyst was separated by centrifugation, and the conversion rate of dimethyl terephthalate and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate were calculated to be 99.86%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.01%.

Claims

1. A method for preparing dimethyl 1,4-cyclohexanedicarboxylate, characterized in that: Under the catalysis of a ruthenium monometallic catalyst supported by ceria, in a hydrogen atmosphere, dimethyl p-toluene dicarboxylate undergoes a hydrogenation reaction in a solvent to obtain the dimethyl 1,4-cyclohexane dicarboxylate. The reaction formula is as follows:

2. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate according to claim 1, characterized in that: The operation steps are: add a certain amount of dimethyl terephthalate and a catalyst into a high-pressure reactor, add an appropriate amount of solvent, fill it with hydrogen at a certain pressure, and react at a specific temperature for a certain time.

3. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate according to claim 1, characterized in that: The selected solvent is C1-C4 alkyl alcohol or ester catalyst.

4. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate according to claim 3, characterized in that: The solvents used were isopropanol or ethyl acetate.

5. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate according to claim 1, characterized in that: Based on the mass ratio of dimethyl terephthalate, the amount of catalyst used is 2wt% to 20wt%, and the amount of solvent used is 5 to 20w / w.

6. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate according to claim 5, characterized in that: Based on the mass ratio of dimethyl terephthalate, the amount of catalyst used is 5wt% to 10wt%, and the amount of solvent used is 8 to 12w / w.

7. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate according to claim 1, characterized in that: The reaction temperature is 100-180°C, the hydrogen pressure is 2Mpa-8MPa, and the reaction time is 0.5h-6h.

8. The method for preparing dimethyl 1,4-cyclohexanedicarboxylate according to claim 1, characterized in that: The loading amount of ruthenium in the cerium dioxide-supported ruthenium monometallic catalyst is 0.1% to 5wt%, and the carrier cerium dioxide comprises three different nano-configurations: nano-particles, nano-rods and nano-cubes.

9. A cerium dioxide-loaded ruthenium monometallic catalyst, wherein the ruthenium loading in the cerium dioxide-loaded ruthenium monometallic catalyst is 0.1% to 5wt%, and the carrier cerium dioxide comprises three different nano-configurations: nanoparticles, nanorods, and nanocubes.

10. The method for preparing the ceria-supported ruthenium monometallic catalyst according to claim 9, comprising the following steps: (I) Preparation of ceria carrier: a certain amount of cerium nitrate hexahydrate was dissolved in deionized water to obtain solution a, a certain amount of sodium hydroxide was dissolved in deionized water to obtain solution b, solution a was added dropwise to solution b at room temperature and stirred for 2 h, transferred to a reactor, hydrothermally reacted at 120°C for 24 h, the product was washed with deionized water and filtered to a pH of 7, dried at 100°C overnight, placed in a muffle furnace and heated to 500°C at a heating rate of 2.5°C / min and maintained for 5 h, to obtain three different nano-configurations of ceria carriers: nanoparticles, nanorods, and nanocubes; (II) Preparation of supported catalysts: A certain amount of ruthenium trichloride was dissolved in deionized water and impregnated into three different nanostructured cerium dioxide supports by an equal volume impregnation method. The mixture was stirred for 4 h, ultrasonicated for 30 min, dried at 100 °C overnight, placed in a muffle furnace and heated to 550 °C at a heating rate of 5 °C / min and maintained for 5 h to obtain the target catalyst.

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