A ruthenium-m bimetallic catalyst, a preparation method thereof and application thereof in selective hydrogenation of dimethyl terephthalate

Abstract

The present application relates to the field of catalysts, discloses a ruthenium-M bimetallic catalyst and a preparation method and application thereof in selective hydrogenation reaction of dimethyl terephthalate, first, the catalyst of the present application takes nitrogen-doped graphene as a carrier, takes ruthenium particles and M (iron, cobalt, nickel, copper) metal particles anchored on the surface of the carrier in high dispersion as active components, and is applied to the reaction of dimethyl terephthalate hydrogenation to prepare dimethyl 1,4-cyclohexanedicarboxylate, and has the characteristics of high catalytic activity, high selectivity and good cycle stability.Secondly, the preparation method of the catalyst is simple, environmentally friendly and low in cost, and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, in particular to a ruthenium-M bimetallic catalyst, a preparation method thereof, and application thereof in the selective hydrogenation reaction of dimethyl terephthalate. Background Art

[0002] Dimethyl 1,4-cyclohexanedicarboxylate (DMCD) is an important raw material and intermediate, widely used in the production of high-performance polyesters and copolyesters. Currently, dimethyl 1,4-cyclohexanedicarboxylate is mainly produced by hydrogenation of dimethyl terephthalate (DMT). In this route, the active components of the catalyst that can be used for the industrial production of DMCD by hydrogenation of DMT are mainly Pd and Ru. Among them, the advantage of Pd-based catalysts is that they can obtain a higher DMCD yield, but their reaction conditions are harsh and require high pressure and high temperature conditions (pressure 20-40MPa, temperature 180-250°C). Ru-based catalysts have higher catalytic activity at low temperature and low pressure, and their cost is also lower.

[0003] Wang Xiaohui et al. (Petrochemical Engineering, 2007, 36(5), 433-436) prepared a highly dispersed Ru / AC catalyst using a reduction deposition method. The catalyst catalyzed DMT hydrogenation at 110°C and 3.0 MPa for 2.5 h, achieving a DMT conversion of 99.0% and a DMCD selectivity of 96.5%. However, the catalyst required a large amount of catalyst and exhibited poor stability, with the active components easily lost and agglomerated after repeated use.

[0004] The patent application with publication number CN101786017A discloses a method for preparing a supported ruthenium-based hydrogenation catalyst. This method uses the volatility of ruthenium tetroxide to controllably anchor it on the surface of activated carbon, preparing a Ru ultra-high dispersion, eggshell-like structure catalyst. It was used for DMT hydrogenation to prepare DMCD, and showed good catalytic activity and selectivity under the conditions of 120°C and 6MPa (H2). After 4 hours of reaction, the DMT conversion rate reached 100%, and the DMCD selectivity could reach 99.4%. At the same time, the catalyst also showed the characteristics of low dosage, fast hydrogenation rate and good stability during the reaction process. However, strong acids and bases as well as a variety of organic solvents are required in the catalyst preparation process, which can easily cause environmental pollution; and the pH value of the hydrogenation liquid needs to be monitored and regulated in real time during the reaction, which is cumbersome.

[0005] Huang et al. (Ind. Eng. Chem. Res. 2014, 53, 4604-4613) found that a modified carbon nanotube-supported RuNi bimetallic catalyst exhibited high DMCD selectivity and remarkable stability. The introduction of Ni, the unique properties of carbon nanotubes, and their anchoring effect on the metal were key to the improved catalytic performance. However, the catalyst preparation process was complex and the expensive carbon nanotubes used as a support made it unsuitable for industrial mass production.

[0006] In summary, Ru-based catalysts are relatively cheap and can exhibit excellent catalytic performance at low temperature and low pressure. The addition of a second metal promoter is conducive to improving the catalytic performance. However, there are still problems such as low catalyst utilization and easy shedding of the active component Ru. In addition, the preparation process of some new catalysts is cumbersome and the conditions are harsh. The catalyst preparation process is not environmentally friendly, which will also limit its large-scale application under industrial conditions. Therefore, it is urgent to develop a catalyst with a simple preparation method, environmental protection, and excellent catalytic activity, high selectivity and high stability in the hydrogenation reaction of dimethyl terephthalate. Summary of the Invention

[0007] To address the above-mentioned technical problems, the present invention provides a ruthenium-M bimetallic catalyst, its preparation method, and its application in the selective hydrogenation of dimethyl terephthalate. First, the catalyst of the present invention utilizes a nitrogen-doped graphene-like support, and comprises highly dispersed ruthenium particles and M (iron, cobalt, nickel, copper) metal particles anchored to the support surface as active components. When applied to the hydrogenation of dimethyl terephthalate to produce dimethyl 1,4-cyclohexanedicarboxylate, the catalyst exhibits high catalytic activity, high selectivity, and good cyclic stability. Second, the catalyst preparation method of the present invention is simple, environmentally friendly, and low-cost, making it suitable for industrial production.

[0008] The specific technical solutions of the present invention are:

[0009] In a first aspect, the present invention provides a ruthenium-M bimetallic catalyst with nitrogen-doped graphene as a carrier, on which ruthenium particles and M metal particles are uniformly loaded; wherein M is one of iron, cobalt, nickel, and copper.

[0010] The catalyst of the present invention comprises a combination of ruthenium and M (iron, cobalt, nickel, or copper) as its active metal components. This combination exhibits high catalytic activity and selectivity in the hydrogenation of dimethyl terephthalate to produce dimethyl 1,4-cyclohexanedicarboxylate. The catalyst's support is a nitrogen-doped graphene-like material. This allows the metal components to be highly dispersed and stably anchored to the support surface, inhibiting their aggregation and precipitation, and imparting excellent cyclic stability to the catalyst. Furthermore, electronic interactions between the metal atoms and nitrogen atoms enable the catalyst to simultaneously achieve high activity, high selectivity, and high stability.

[0011] Preferably, the ruthenium particles and M metal particles account for 5-25% and 0.5-3% of the total mass of the catalyst respectively.

[0012] Preferably, the particle sizes of the ruthenium particles and the M metal particles are 0.5-1.5 nanometers and less than 0.5 nanometers, respectively.

[0013] The inventors' team discovered that the particle size of metal particles is crucial to catalyst performance. Within the above particle size, metal particles can exert better catalytic activity.

[0014] In a second aspect, the present invention provides a method for preparing a ruthenium-M bimetallic catalyst, comprising the following steps:

[0015] (1) Glucose, melamine, ruthenium trichloride and M metal salt are mixed evenly as a precursor.

[0016] (2) Grind the precursor into powder and calcine it in N2 atmosphere.

[0017] (3) The product obtained after calcination is acid-washed, washed with water until neutral, and vacuum-dried to obtain a catalyst.

[0018] Preferably, in step (1), the mass ratio of glucose to melamine is ≥1:4.

[0019] The ratio of glucose to melamine significantly affects the nitrogen content and two-dimensional layer structure of the prepared nitrogen-doped graphene-like materials. At the above ratio, relatively ideal nitrogen-doped graphene-like materials can be obtained.

[0020] Preferably, in step (1), the mass ratio of the ruthenium trichloride to the M metal salt is 1:0.08-0.24; the mass ratio of the glucose to the M metal salt is 1:0.017-0.049.

[0021] The ratio between ruthenium and M metal and the ratio between metal and carrier have a significant impact on the performance of the catalyst. The present invention team found through experiments that the performance is better within the above ratio range.

[0022] Preferably, in step (2), during the calcination process, the heating rate is 3-5°C / min, the calcination temperature is 600-800°C, and the calcination time is 2-6h.

[0023] The calcination conditions have a significant impact on the micromorphology / nitrogen doping amount of the formed nitrogen-doped graphene and the particle size of the metal particles. Under the above calcination conditions, ideal nitrogen-doped graphene micromorphology / nitrogen doping amount and metal particle size can be obtained.

[0024] Preferably, in step (3), the pickling is performed using a hydrochloric acid solution with a concentration of 5-15 wt%.

[0025] In a third aspect, the present invention provides the use of a ruthenium-M bimetallic catalyst in the selective hydrogenation of dimethyl terephthalate to prepare dimethyl 1,4-cyclohexanedicarboxylate.

[0026] In a fourth aspect, the present invention provides a method for preparing dimethyl 1,4-cyclohexanedicarboxylate by selective hydrogenation of dimethyl terephthalate, comprising the following steps: adding dimethyl terephthalate, the ruthenium-M bimetallic catalyst according to any one of claims 1 to 3 or the ruthenium-M bimetallic catalyst obtained by the preparation method according to any one of claims 4 to 7, and a reaction solvent to a reactor, introducing hydrogen to replace the air in the reactor, and finally performing a pressurized heating reaction.

[0027] Preferably, the mass ratio of the ruthenium-M bimetallic catalyst to dimethyl terephthalate is 1:25-65.

[0028] Preferably, the reaction solvent is methanol, ethanol, isopropanol, n-butanol, cyclohexanol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, tetrahydrofuran, acetone, cyclohexane, n-hexane, dioxane, methyl acetate, ethyl acetate, preferably isopropanol, cyclohexane, n-hexane or dioxane.

[0029] Preferably, the pressurized heating reaction is carried out under the conditions of pressurizing to 2-3 MPa and reacting at 140-220° C. for 1-7 hours.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The metal active component of the catalyst of the present invention is a combination of ruthenium and M (iron, cobalt, nickel or copper), which has high catalytic activity and selectivity in the reaction of hydrogenating dimethyl terephthalate to prepare dimethyl 1,4-cyclohexanedicarboxylate.

[0032] (2) The carrier of the catalyst of the present invention is nitrogen-doped graphene, which can, on the one hand, make the metal components highly dispersed and stably anchored on the carrier surface, inhibit the aggregation and precipitation of the metal components, and endow the catalyst with excellent cyclic stability; on the other hand, there is electronic interaction between the metal atoms and nitrogen atoms, so that the characteristics of high activity, high selectivity and high stability can be achieved simultaneously.

[0033] (3) The preparation method of the catalyst of the present invention is simple, and the process does not require the use of large amounts of strong acids, strong bases, and organic solvents, making it more environmentally friendly. In addition, the metal active components selected are relatively inexpensive ruthenium and M (iron, cobalt, nickel, or copper), which can effectively reduce the cost of industrial production. Therefore, the catalyst of the present invention is more suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a scanning electron microscope image of the catalyst prepared in Example 1. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the embodiments.

[0036] Overall embodiment

[0037] A ruthenium-M bimetallic catalyst uses nitrogen-doped graphene as a carrier, on which ruthenium particles and M metal particles are uniformly loaded; wherein M is one of iron, cobalt, nickel and copper.

[0038] Preferably, the ruthenium particles and the M metal particles account for 5-25% and 0.5-3% of the total mass of the catalyst, respectively; the particle sizes of the ruthenium particles and the M metal particles are 0.5-1.5 nanometers and less than 0.5 nanometers, respectively.

[0039] A method for preparing a ruthenium-M bimetallic catalyst comprises the following steps:

[0040] (1) Glucose, melamine, ruthenium trichloride and M metal salt are mixed evenly as a precursor.

[0041] Preferably, the mass ratio of glucose to melamine is ≥1:4. The mass ratio of ruthenium trichloride to M metal salt is 1:0.08-0.24; the mass ratio of glucose to M metal salt is 1:0.017-0.049.

[0042] (2) Grind the precursor into powder and calcine it in N2 atmosphere.

[0043] Preferably, during the calcination process, the heating rate is 3-5°C / min, the calcination temperature is 600-800°C, and the calcination time is 2-6h.

[0044] (3) The product obtained after calcination is acid-washed, washed with water until neutral, and vacuum-dried to obtain a catalyst.

[0045] Preferably, the pickling is performed using a hydrochloric acid solution with a concentration of 5-15 wt%.

[0046] A method for preparing dimethyl 1,4-cyclohexanedicarboxylate by selective hydrogenation of dimethyl terephthalate comprises the following steps: adding dimethyl terephthalate, the ruthenium-M bimetallic catalyst according to any one of claims 1 to 3 or the ruthenium-M bimetallic catalyst obtained by the preparation method according to any one of claims 4 to 7, and a reaction solvent into a reactor, injecting hydrogen to replace the air in the reactor, and finally performing a pressurized heating reaction.

[0047] Preferably, the mass ratio of the ruthenium-M bimetallic catalyst to dimethyl terephthalate is 1:25-65. The reaction solvent is methanol, ethanol, isopropanol, n-butanol, cyclohexanol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, tetrahydrofuran, acetone, cyclohexane, n-hexane, dioxane, methyl acetate, or ethyl acetate, preferably isopropanol, cyclohexane, n-hexane, or dioxane. The pressurized heating reaction is performed at a pressure of 2-3 MPa and a reaction temperature of 140-220°C for 1-7 hours.

[0048] Example 1

[0049] 0.9 g of glucose, 3.6 g of melamine, 9 mL of RuCl3 solution (0.01 g / mL) and 0.03 g of anhydrous ferric chloride were mixed in a mortar and then dried in an oven at 80°C to form a solid.

[0050] The above solid was ground into powder, and then transferred into a tube furnace with N2 atmosphere and calcined at 700°C for 4 h (heating rate 4°C / min).

[0051] The catalyst obtained by pyrolysis was further treated with 50 mL of HCl (10 wt%) solution for 6.0 h to remove acid-soluble impurities. The acid-treated sample was washed with a large amount of distilled water until no chloride ions were detected, and then washed with 50 mL of acetone. Finally, the sample was dried in a vacuum oven at 80°C for 12 h to obtain a ruthenium-iron bimetallic catalyst, in which the particle sizes of the ruthenium particles and the M metal particles were 0.5-1.5 nm and less than 0.5 nm, respectively. The high-resolution electron microscopy image of the catalyst prepared according to the above method is shown in FIG. Figure 1 shown.

[0052] Example 2

[0053] The preparation method was prepared with reference to Example 1, except that the mass of anhydrous ferric chloride added was 0.015-0.045 g, that is, the mass ratios of ruthenium chloride and anhydrous ferric chloride were controlled to be 1:0.08, 1:0.16 and 1:0.24, respectively, during the preparation process.

[0054] Example 3

[0055] 0.9 g of glucose, 3.6 g of melamine, 9 mL of RuCl3 solution (0.01 g / mL) and 0.03 g of anhydrous cobalt chloride were mixed in a mortar and then dried in an oven at 80°C to form a solid.

[0056] The above solid was ground into powder, and then transferred into a tube furnace with N2 atmosphere and calcined at 700°C for 4 h (heating rate 4°C / min).

[0057] The catalyst obtained by pyrolysis was further treated with 50 mL of 10 wt% HCl solution for 6.0 h to remove acid-soluble impurities. The acid-treated sample was washed with a large amount of distilled water until no chloride ions were detected, and then washed with 50 mL of acetone. Finally, the sample was dried in a vacuum oven at 80°C for 12 h to obtain a ruthenium-cobalt bimetallic catalyst, wherein the particle sizes of the ruthenium particles and the M metal particles were 0.5-1.5 nm and less than 0.5 nm, respectively.

[0058] Example 4

[0059] 0.9 g of glucose, 3.6 g of melamine, 9 mL of RuCl3 solution (0.01 g / mL) and 0.03 g of anhydrous nickel chloride were mixed in a mortar and then dried in an oven at 80°C to form a solid.

[0060] The above solid was ground into powder, and then transferred into a tube furnace with N2 atmosphere and calcined at 700°C for 4 h (heating rate 4°C / min).

[0061] The catalyst obtained by pyrolysis was further treated with 50 mL of 10 wt% HCl solution for 6.0 h to remove acid-soluble impurities. The acid-treated sample was washed with a large amount of distilled water until no chloride ions were detected, and then washed with 50 mL of acetone. Finally, the sample was dried in a vacuum oven at 80°C for 12 h to obtain a ruthenium-nickel bimetallic catalyst, wherein the particle size of the ruthenium particles and the M metal particles were 0.5-1.5 nm and less than 0.5 nm, respectively.

[0062] Example 5

[0063] 0.9 g of glucose, 3.6 g of melamine, 9 mL of RuCl3 solution (0.01 g / mL) and 0.03 g of anhydrous copper chloride were mixed in a mortar and then dried in an oven at 80°C to form a solid.

[0064] The above solid was ground into powder, and then transferred into a tube furnace with N2 atmosphere and calcined at 700°C for 4 h (heating rate 4°C / min).

[0065] The catalyst obtained by pyrolysis was further treated with 50 mL of 10 wt% HCl solution for 6.0 hours to remove acid-soluble impurities. The acid-treated sample was washed with a large amount of distilled water until no chloride ions were detected, and then washed with 50 mL of acetone. Finally, the sample was dried in a vacuum oven at 80°C for 12 hours to obtain a ruthenium-copper bimetallic catalyst, wherein the particle sizes of the ruthenium particles and the M metal particles were 0.5-1.5 nanometers and less than 0.5 nanometers, respectively.

[0066] Application Example 1 (Different Solvents)

[0067] Take 0.1g of the catalyst prepared in Example 1, 4.5g of DMT and 10mL of solvent (methanol, ethanol, isopropanol, n-butanol, cyclohexanol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, tetrahydrofuran, acetone, cyclohexane, n-hexane, dioxane, methyl acetate, ethyl acetate) and add to autoclave (20mL) and mix uniformly; Subsequently, H2 is charged into the reactor and replaced 3 times to evacuate the air remaining in the reactor, finally pressurized to 2.5MPa and sealed, put into an oil bath and heated to 140°C, open magnetic stirring (1000rpm), and the reaction time is 4h. After completion of the reaction, treat that the autoclave is cooled to room temperature, centrifuge the reaction solution and the solid catalyst, take the supernatant and use capillary gas chromatography to determine the relative purity, and analyze the relative purity by external standard method.

[0068] The reaction results are shown in the following table.

[0069]

[0070]

[0071] Application Example 2 (Ruthenium trichloride and anhydrous ferric chloride in different ratios)

[0072] 0.1 g of the catalyst prepared in Example 2, 4.5 g of DMT, and 10 mL of cyclohexane were added to a 20 mL autoclave and mixed uniformly; H was then introduced into the autoclave and replaced three times to evacuate the remaining air in the autoclave. The reaction mixture was then pressurized to 2.5 MPa and sealed, placed in an oil bath and heated to 140° C., magnetic stirring was turned on (1000 rpm), and the reaction time was 3 h. After the reaction was completed, the autoclave was cooled to room temperature, the reaction solution and the solid catalyst were centrifuged, the supernatant was taken, and the mixture was determined by capillary gas chromatography and quantitatively analyzed by external standard method. The reaction results are shown in the table below.

[0073] Mass ratio of ruthenium trichloride and anhydrous ferric chloride 1∶0.08 1∶0.16 1∶0.24 Conversion rate of dimethyl terephthalate (%) 80.6 87.7 77.6 Selectivity of dimethyl 1,4-cyclohexanedicarboxylate (%) 99.4 99.8 98.7

[0074] Application Example 3 (different time)

[0075] 0.1 g of the catalyst prepared in Example 1, 4.5 g of DMT, and 10 mL of cyclohexane were added to a 20 mL autoclave and mixed uniformly. The autoclave was then filled with H2 and replaced three times to evacuate the remaining air in the autoclave. The autoclave was then pressurized to 2.5 MPa and sealed. The autoclave was placed in an oil bath and heated to 140° C. with magnetic stirring at 1000 rpm for 1 to 5 h. After the reaction was completed, the autoclave was cooled to room temperature, the reaction solution and the solid catalyst were separated by centrifugation, and the supernatant was measured by capillary gas chromatography and quantitatively analyzed by external standard method. The reaction results are shown in the following table.

[0076] Reaction time (h) 1 2 3 4 5 Conversion rate of dimethyl terephthalate (%) 42.0 66.2 87.7 97.0 100 Selectivity of dimethyl 1,4-cyclohexanedicarboxylate (%) 99.7 99.8 99.9 99.9 100

[0077] Application Example 4 (different temperatures)

[0078] 0.1 g of the catalyst prepared in Example 1, 4.5 g of DMT, and 10 mL of cyclohexane were added to a 20 mL autoclave and mixed uniformly. H2 was then introduced into the autoclave and replaced three times to evacuate the remaining air in the autoclave. The autoclave was then pressurized to 2.5 MPa and sealed. The mixture was placed in an oil bath and heated to 140-220° C. with magnetic stirring at 1000 rpm for 1 h. After the reaction was complete, the autoclave was cooled to room temperature, the reaction solution and the solid catalyst were centrifuged, and the supernatant was measured by capillary gas chromatography and quantitatively analyzed by external standard method. The reaction results are shown in the table below.

[0079] Reaction temperature (℃) 140 160 180 200 220 Conversion rate of dimethyl terephthalate (%) 42.0 61.9 72.7 80.7 87.3 Selectivity of dimethyl 1,4-cyclohexanedicarboxylate (%) 99.7 99.8 99.8 100 100

[0080] Application Example 5 (Different Catalyst Doses)

[0081] 0.1 g of the catalyst prepared in Example 1, 2.5 to 6.5 g of DMT, and 10 mL of cyclohexane were added to a 20 mL autoclave and mixed uniformly. H2 was then introduced into the autoclave and replaced three times to evacuate the remaining air in the autoclave. The autoclave was then pressurized to 2.5 MPa and sealed. The autoclave was placed in an oil bath and heated to 140°C with magnetic stirring at 1000 rpm for 3 hours. After the reaction was complete, the autoclave was cooled to room temperature, the reaction solution and the solid catalyst were centrifuged, and the supernatant was measured by capillary gas chromatography and quantitatively analyzed by external standard method. The reaction results are shown in the table below.

[0082] DMT dosage (g) 2.5 3.5 4.5 5.5 6.5 Conversion rate of dimethyl terephthalate (%) 100 96.3 87.7 74.9 59.8 Selectivity of dimethyl 1,4-cyclohexanedicarboxylate (%) 100 99.9 99.9 98.6 98.7

[0083] Application Example 6 (different number of cycles)

[0084] 0.1 g of the catalyst prepared in Example 1, 4.5 g of DMT, and 10 mL of cyclohexane solvent were added to a 20 mL autoclave and mixed uniformly. The autoclave was then filled with H2 and replaced three times to evacuate the remaining air in the autoclave. The mixture was then pressurized to 2.5 MPa and sealed. The mixture was placed in an oil bath and heated to 140°C with magnetic stirring at 1000 rpm for 3 hours. After the reaction, the autoclave was cooled to room temperature, the reaction solution and the solid catalyst were centrifuged, and the supernatant was measured by capillary gas chromatography and quantitatively analyzed by external standard method. The used catalyst was washed three times with chloroform to remove reactants and products adsorbed on the surface and in the pores of the material, dried in a vacuum oven at 80°C, and weighed. The next hydrogenation experiment was carried out according to the above-mentioned feed ratio and method.

[0085] The total number of catalyst recycling times was 5. The reaction results are shown in the following table.

[0086] Use times Conversion rate of dimethyl terephthalate (%) Selectivity of dimethyl 1,4-cyclohexanedicarboxylate (%) 1 87.7 99.9 2 87.7 100 3 87.5 99.7 4 87.3 99.8 5 87.1 99.6

[0087] Application Example 7 (Ruthenium-Cobalt Bimetallic Catalyst)

[0088] 0.1 g of the ruthenium-cobalt bimetallic catalyst prepared in Example 3, 4.5 g of DMT, and 10 mL of cyclohexane solvent were added to a 20 mL autoclave and mixed thoroughly. H₂ was then introduced into the autoclave and replaced three times to evacuate the remaining air. The autoclave was then pressurized to 2.5 MPa and sealed. The mixture was placed in an oil bath and heated to 140° C. with magnetic stirring at 1000 rpm for 3 hours. After the reaction was complete, the autoclave was cooled to room temperature, the reaction solution and the solid catalyst were separated by centrifugation, and the supernatant was measured by capillary gas chromatography and quantitatively analyzed by the external standard method. The results showed that the conversion of dimethyl terephthalate was 80.4%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.1%.

[0089] Application Example 8 (Ruthenium-Nickel Bimetallic Catalyst)

[0090] 0.1 g of the ruthenium-nickel bimetallic catalyst prepared in Example 4, 4.5 g of DMT, and 10 mL of cyclohexane solvent were added to a 20 mL autoclave and mixed uniformly. H 2 was then introduced into the autoclave and replaced three times to evacuate the remaining air in the autoclave. The autoclave was then pressurized to 2.5 MPa and sealed. The mixture was placed in an oil bath and heated to 140° C. with magnetic stirring at 1000 rpm for 3 hours. After the reaction was complete, the autoclave was cooled to room temperature, the reaction solution and the solid catalyst were centrifuged, and the supernatant was measured by capillary gas chromatography and quantitatively analyzed by the external standard method. The results showed that the conversion of dimethyl terephthalate was 89.2%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.6%.

[0091] Application Example 9 (Ruthenium-Copper Bimetallic Catalyst)

[0092] 0.1 g of the ruthenium-copper bimetallic catalyst prepared in Example 4, 4.5 g of DMT, and 10 mL of cyclohexane solvent were added to a 20 mL autoclave and mixed uniformly. H 2 was then introduced into the autoclave and replaced three times to evacuate the remaining air in the autoclave. The autoclave was then pressurized to 2.5 MPa and sealed. The mixture was placed in an oil bath and heated to 140° C. with magnetic stirring at 1000 rpm for 3 hours. After the reaction was complete, the autoclave was cooled to room temperature, the reaction solution and the solid catalyst were centrifuged, and the supernatant was measured by capillary gas chromatography and quantitatively analyzed by the external standard method. The results showed that the conversion of dimethyl terephthalate was 91.3%, and the selectivity of dimethyl 1,4-cyclohexanedicarboxylate was 99.7%.

[0093] Unless otherwise specified, the raw materials and equipment used in the present invention are commonly used in the art; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0094] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. Application of a ruthenium-M bimetallic catalyst in the selective hydrogenation of dimethyl terephthalate to dimethyl 1,4-cyclohexanedicarboxylate, characterized in that: The preparation method of the ruthenium-M bimetallic catalyst comprises: (1) Glucose, melamine, ruthenium trichloride and M metal salt are mixed as a precursor; the mass ratio of glucose to melamine is ≥1:4; (2) Grind the precursor into powder and calcine in N2 atmosphere; (3) washing the calcined product with acid, washing with water until neutral, and vacuum drying to obtain a ruthenium-M bimetallic catalyst; The ruthenium-M bimetallic catalyst uses nitrogen-doped graphene as a carrier, on which ruthenium particles and M metal particles are uniformly loaded; M is iron, cobalt, nickel or copper; the ruthenium particles and M metal particles account for 5-25% and 0.5-3% of the total mass of the catalyst, respectively; the particle sizes of the ruthenium particles and the M metal particles are 0.5-1.5 nanometers and less than 0.5 nanometers, respectively; The reaction solvent used in the selective hydrogenation is methanol, ethanol, isopropanol, n-butanol, cyclohexanol, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, cyclohexane, n-hexane, dioxane or ethyl acetate.

2. The use according to claim 1, characterized in that: In step (1), the mass ratio of ruthenium trichloride to M metal salt is 1:(0.08-0.24); the mass ratio of glucose to M metal salt is 1:(0.017-0.049).

3. The use according to claim 1, characterized in that: In step (2), during the roasting process, the heating rate is 3-5°C / min, the roasting temperature is 600-800°C, and the roasting time is 2-6h.

4. The use according to claim 1, wherein: In step (3), the pickling is performed using a hydrochloric acid solution with a concentration of 5-15wt%.

5. A method for preparing dimethyl 1,4-cyclohexanedicarboxylate by selective hydrogenation of dimethyl terephthalate, characterized in that: The following steps are involved: Add dimethyl terephthalate, ruthenium-M bimetallic catalyst and reaction solvent into the reactor, fill with hydrogen to replace the air in the reactor, and finally perform pressurized heating reaction; The preparation method of the ruthenium-M bimetallic catalyst comprises: (1) Glucose, melamine, ruthenium trichloride and M metal salt are mixed as a precursor; the mass ratio of glucose to melamine is ≥1:4; (2) Grind the precursor into powder and calcine in N2 atmosphere; (3) washing the calcined product with acid, washing with water until neutral, and vacuum drying to obtain a ruthenium-M bimetallic catalyst; The ruthenium-M bimetallic catalyst uses nitrogen-doped graphene as a carrier, on which ruthenium particles and M metal particles are uniformly loaded; M is iron, cobalt, nickel or copper; the ruthenium particles and M metal particles account for 5-25% and 0.5-3% of the total mass of the catalyst, respectively; the particle sizes of the ruthenium particles and the M metal particles are 0.5-1.5 nanometers and less than 0.5 nanometers, respectively; The reaction solvent is methanol, ethanol, isopropanol, n-butanol, cyclohexanol, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, cyclohexane, n-hexane, dioxane or ethyl acetate.

6. The method according to claim 5, wherein: The mass ratio of the ruthenium-M bimetallic catalyst to dimethyl terephthalate is 1:(25-65).

7. The method according to claim 5, wherein: The conditions for the pressurized heating reaction are to pressurize to 2-3 MPa and react at 140-220° C. for 1-7 h.

8. The method according to claim 5, wherein: In step (1), the mass ratio of ruthenium trichloride to M metal salt is 1:(0.08-0.24); the mass ratio of glucose to M metal salt is 1:(0.017-0.049).

9. The method according to claim 5, wherein: In step (2), during the roasting process, the heating rate is 3-5°C / min, the roasting temperature is 600-800°C, and the roasting time is 2-6h.

10. The method according to claim 5, wherein: In step (3), the pickling is performed using a hydrochloric acid solution with a concentration of 5-15wt%.

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