Supported ruthenium-based hydrogenation catalyst, preparation method thereof and application of supported ruthenium-based hydrogenation catalyst in selective hydrogenation reaction of aromatic ester compounds

Abstract

The invention discloses a supported ruthenium-based hydrogenation catalyst and a preparation method and application thereof in selective hydrogenation reaction of aromatic ester compounds, the catalyst comprises a carrier and an active component supported on the carrier, the carrier is manganese dioxide, the active component is a metal ruthenium component, and the loading amount of the noble metal ruthenium element in the catalyst is 1.0-5.0 wt%. The preparation method of the catalyst is simple and easy to implement, and the catalyst can be synthesized by using a cheap ruthenium precursor and an oxide carrier; reaction substrates are cheap and easy to obtain; the obtained catalyst has high catalytic activity and selectivity on aromatic ester hydrogenation reaction, and the substrate applicability is wide; the reaction system is clean, safe, high in operability and good in repeatability, can be effectively recycled, and is beneficial to reduction of product separation and process operation cost, so that the economic benefit of industrial production is improved.

Description

Technical Field

[0001] The invention relates to the technical field of industrial catalysis, and in particular to a supported ruthenium-based hydrogenation catalyst, a preparation method thereof, and an application of the catalyst in the selective hydrogenation reaction of aromatic ester compounds. Background Art

[0002] Aromatic ester compounds are a class of organic compounds with aromatic rings and ester groups. They have good chemical stability and volatility and are widely used in cosmetics, fragrances, food additives, medicine and other fields.

[0003] Dimethyl terephthalate is a white crystalline solid at room temperature and pressure. It contains two ester groups and is a monomer of polyester. It is mainly used to synthesize polyester fibers, resins, films, polyester paints and engineering plastics. Dimethyl terephthalate is mainly used to make polyester resins, and then to make films and fibers, as well as high-strength polyester insulating varnishes. Polyester films are mainly used as electrical insulating materials and for making films (such as base materials for movie films, X-ray films, photographic films, and audio tapes, video tapes, and computer tapes). The most common use of polyester resins is to make fibers for fabrics, fishing nets, carpets, tire cords, etc. It can also be used to produce plasticizer dioctyl terephthalate.

[0004] Among them, 1,4-cyclohexanedimethanol (CHDM), the selective hydrogenation product of dimethyl terephthalate (DMT), is a very valuable chemical intermediate and is widely used in the polymer industry, especially as a material for reinforcing fibers and polyesters, with excellent heat resistance and physical strength.

[0005] So far, the industrially recognized route for synthesizing CHDM is a two-step process. The two-step hydrogenation first hydrogenates the benzene ring of DMT to produce dimethyl 1,4-cyclohexanedicarboxylate (DMCD), and then hydrogenates the ester group to obtain the final target product CHDM. Among them, palladium, ruthenium, bimetallic and non-precious metal catalysts are mostly used for benzene ring hydrogenation, while the catalyst for ester group hydrogenation is mainly copper-based catalyst. As early as 1962, William et al. used 5% Ru / C catalyst and DMCD as solvent to hydrogenate the benzene ring at 120°C and 6.8MPa. The DMT conversion rate and DMCD selectivity were both greater than 95%. This is also the earliest study of Ru-based catalysts in the preparation of DMCD. Using ruthenium-based catalysts, the DMT conversion rate and DMCD selectivity can be close to 100%. Choosing a suitable catalyst is crucial to the effect of the hydrogenation reaction. At present, the reaction conditions of existing catalysts are relatively harsh. Generally, a high reaction pressure and a high reaction temperature are required to achieve a 100% aromatic ester conversion rate. Its low-temperature and low-pressure activity is low, and the selectivity of the target product is poor. In addition, the noble metal loading is high, and the catalyst is prone to metal component loss and agglomeration during the reaction, making the catalyst stability low. For supported metal catalysts, the catalyst synthesis method has a significant impact on the physicochemical properties such as metal particle size and dispersion, the configuration of metal and carrier, and the stability of active components. In order to obtain efficient and stable catalyst carriers and active metals, the selection is crucial. Therefore, based on suitable carriers and noble metal active components, by optimizing the synthesis method and reaction conditions, it is possible to obtain aromatic ester compound hydrogenation catalysts with high activity and high stability under relatively mild conditions, and significantly reduce the noble metal loading, further reducing the catalyst synthesis cost, so as to adapt to the large-scale application of catalysts. Summary of the invention

[0006] In view of the problems arising in the hydrogenation reaction of aromatic ester compounds, the purpose of the present invention is to provide a new type of highly selective and highly stable high-efficiency supported catalyst and a preparation method thereof and application in the hydrogenation reaction of aromatic ester compounds.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A supported ruthenium-based hydrogenation catalyst comprises a carrier and an active component supported on the carrier, wherein the carrier is manganese dioxide, the active component is a metal ruthenium component, and the loading amount of the noble metal ruthenium element in the catalyst is 1.0-5.0wt%.

[0009] Furthermore, the specific surface area of ​​the manganese dioxide is between 100 and 200 m 2 / g.

[0010] The present invention also provides a method for preparing a supported ruthenium-based hydrogenation catalyst, comprising the following steps:

[0011] 1) Dissolve the soluble metal salt of Ru in water to form a precursor aqueous solution, add manganese dioxide powder, and stir it thoroughly at 30-50°C to make the substances fully mixed;

[0012] 2) Then, urea is added (urea is a precipitant, the purpose of which is to deposit the metal on the surface of the carrier), and then the mixture is stirred at 70°C to 110°C to deposit the Ru metal on the surface of the carrier at high temperature, and the water is evaporated, washed, and dried to obtain a solid powder;

[0013] 3) The solid powder obtained in step 2) is placed in a mixed atmosphere of H2 and N2 containing 5-30v% H2 for calcination reduction, the reduction temperature is set to 300-500°C, the reduction time is set to 2-6h, and finally the supported ruthenium-based hydrogenation catalyst is obtained.

[0014] Furthermore, the stirring time in step 1) is 3-5h.

[0015] Furthermore, in step 2), the stirring temperature is 80-90° C. and the stirring time is 8-10 h.

[0016] The present invention also provides the use of the supported ruthenium-based hydrogenation catalyst in the selective hydrogenation reaction of aromatic ester compounds, wherein the aromatic ester compound is dimethyl terephthalate, dioctyl terephthalate or dibutyl terephthalate, and the benzene ring in the aromatic ester compound is hydrogenated and reduced to a 1,4-cyclohexane ring.

[0017] The selective hydrogenation reaction of the present invention comprises the following steps: mixing the supported ruthenium-based hydrogenation catalyst, solvent and aromatic ester compounds, reacting for 2 to 8 hours at 130 to 160° C. and a hydrogen pressure of 3 to 5.0 MPa, and rapidly cooling the reactor to room temperature after the reaction to release the remaining hydrogen in the reactor, and finally separating the reaction liquid from the catalyst and recovering the catalyst to obtain the target product. The mass of the catalyst is 5 to 20% of the mass of the aromatic ester compounds, the solvent is methanol or dimethyl 1,4-cyclohexanedicarboxylate, and the dispersion concentration of the aromatic ester compounds in the solvent is 0.05 to 0.5 g / mL.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) The catalyst preparation method of the present invention is simple, the preparation process conditions are easy to achieve, the catalyst preparation cost can be reduced, and it is suitable for large-scale promotion and use.

[0020] 2) The catalyst preparation method of the present invention is simple and easy, and can be synthesized using a cheap ruthenium precursor and an oxide carrier; the reaction substrate is cheap and readily available; the obtained catalyst has high catalytic activity and selectivity for aromatic ester hydrogenation reaction, and has a wide substrate applicability; the reaction system is clean, safe, highly operable, and has good repeatability, and can be effectively recycled, which is beneficial to reducing product separation and process operation costs, thereby improving the economic benefits of industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the X-ray diffraction (XRD) diagram of the catalyst of Example 7 of the present invention.

[0022] Figure 2 It is the comparison result of X-ray diffraction (XRD) diagram of the catalyst of Example 1 of the present invention before and after the reaction. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0024] Example 1

[0025] Catalyst preparation: First, weigh 5.0 g of manganese dioxide carrier (the specific surface area of ​​manganese dioxide is 127 m 2 / g, the same below) in a beaker, and after adding 150mL of deionized water, add 0.513g of RuCl3 (i.e. containing 0.25g of Ru), stir at 40°C and 500rpm for 4h to fully mix the substances. Then add 2.5g of urea, stir at 90°C and 500rpm for 9h, deposit Ru metal on the surface of the carrier at high temperature, evaporate the water, and then wash it with deionized water to obtain a solid sample. Dry it in an oven at 80°C for 12 hours and then grind it into powder, which is recorded as the unreduced Ru / MnO2 catalyst before the reaction. Take the above sample and place it in a U-shaped reactor, reduce it at 400°C for 4 hours in a mixed gas of H2 and N2 containing 15v% H2, and obtain a catalyst with a loading of 5.0wt% of the precious metal ruthenium element, which is recorded as the reduced Ru / MnO2 catalyst before the reaction.

[0026] Example 2

[0027] The catalyst prepared in Example 1 was used to carry out a selective hydrogenation experiment of dimethyl terephthalate. The reaction was carried out in a high-pressure reactor, with 1 g of dimethyl terephthalate as substrate and 15 mL of methanol as solvent, 0.2 g of catalyst added, H2 pressure set to 4.0 MPa, reaction temperature set to 140°C, and stirring speed set to 600 rpm / min. After the reaction was completed, the catalyst was filtered and separated from the reaction liquid, and the conversion rate of the raw material and the selectivity of the target product were analyzed by Agilent 8860 gas chromatograph, and the target product was dimethyl 1,4-cyclohexanedicarboxylate. The experimental results are shown in Table 1.

[0028] Table 1 Product analysis results of dimethyl terephthalate hydrogenation reaction

[0029]

[0030] Example 3

[0031] The catalyst prepared in Example 1 was used to carry out a selective hydrogenation experiment of dimethyl terephthalate. The reaction was carried out in a high-pressure reactor, with 1 g of substrate dimethyl terephthalate, 15 mL of solvent dimethyl 1,4-cyclohexanedicarboxylate, 0.2 g of catalyst, H2 pressure of 4.0 MPa, reaction temperature of 150°C, and stirring speed of 600 rpm / min. After the reaction was completed, the catalyst was filtered and separated from the reaction liquid, and the conversion rate of the raw material and the selectivity of the target product were analyzed by Agilent 8860 gas chromatograph. The target product was dimethyl 1,4-cyclohexanedicarboxylate. The experimental results are shown in Table 2.

[0032] Table 2 Product analysis results of dimethyl terephthalate hydrogenation reaction

[0033]

[0034] Example 4

[0035] Catalyst preparation: First, weigh 5.0g of manganese dioxide carrier in a beaker, add 150mL of deionized water, add 0.103g of RuCl3 (i.e., containing 0.05g of Ru), stir at 40°C and 500rpm for 4h, then add 2.5g of urea, stir at 90°C and 500rpm for 9h, deposit Ru metal on the carrier surface at high temperature, evaporate the water, and then wash with deionized water to obtain a solid sample. Dry it in an oven at 80°C for 12 hours and grind it into powder. Take the above sample and place it in a U-shaped reactor, reduce it at 400°C for 4 hours in a mixture of H2 and N2 containing 15v% H2, and obtain a catalyst with a noble metal ruthenium element loading of 1.0wt%.

[0036] Example 5

[0037] The catalyst prepared in Example 4 was used to carry out a selective hydrogenation experiment of dimethyl terephthalate. The reaction was carried out in a high-pressure reactor, with 4 g of dimethyl terephthalate as substrate and 15 mL of methanol as solvent, 0.2 g of catalyst added, H2 pressure set to 4.0 MPa, reaction temperature set to 150°C, and stirring speed set to 600 rpm / min. After the reaction was completed, the catalyst was filtered and separated from the reaction liquid, and the conversion rate of the raw material and the selectivity of the target product were analyzed by Agilent 8860 gas chromatograph, and the target product was dimethyl 1,4-cyclohexanedicarboxylate. The experimental results are shown in Table 3.

[0038] Table 3 Product analysis results of dimethyl terephthalate hydrogenation reaction

[0039]

[0040] Example 6

[0041] The catalyst prepared in Example 4 was used to carry out a selective hydrogenation experiment of dimethyl terephthalate. The reaction was carried out in a high-pressure reactor, with 4 g of dimethyl terephthalate as substrate and 15 mL of dimethyl 1,4-cyclohexanedicarboxylate as solvent, 0.2 g of catalyst was added, the H2 pressure was set to 4.0 MPa, the reaction temperature was 150°C, and the stirring speed was 600 rpm / min. After the reaction was completed, the catalyst was filtered and separated from the reaction liquid, and the conversion rate of the raw material and the selectivity of the target product were analyzed by Agilent 8860 gas chromatograph. The target product was dimethyl 1,4-cyclohexanedicarboxylate. The experimental results are shown in Table 4.

[0042] Table 4 Product analysis results of dimethyl terephthalate hydrogenation reaction

[0043]

[0044] Example 7

[0045] Catalyst preparation: First, weigh 5.0g of manganese dioxide carrier in a beaker, add 150mL of deionized water, then add 0.513g of RuCl3 (i.e., containing 0.25g of Ru), stir at 40°C and 500rpm for 4h, then add 2.5g of urea, stir at 90°C and 500rpm for 9h, deposit Ru metal on the carrier surface at high temperature, evaporate the water, and then wash with deionized water to obtain a solid sample. Dry it in an oven at 80°C for 12 hours and grind it into powder. Take the above sample and place it in a U-shaped reactor, reduce it at 400°C in a mixture of H2 and N2 containing 15v% H2 for 4 hours to obtain a catalyst with a noble metal ruthenium element loading of 5.0wt%.

[0046] Example 8

[0047] The catalyst prepared in Example 7 was used to carry out a selective hydrogenation experiment of dimethyl terephthalate. The reaction was carried out in a high-pressure reactor, with 10 g of dimethyl terephthalate as substrate and 35 mL of dimethyl 1,4-cyclohexanedicarboxylate as solvent, 0.5 g of catalyst, and the H2 pressure was set to 4.0 MPa, the reaction temperature was 150°C, and the stirring speed was 600 rpm / min. After the reaction was completed, the catalyst was filtered and separated from the reaction liquid, and the conversion rate of the raw material and the selectivity of the target product were analyzed by Agilent 8860 gas chromatograph. The target product was dimethyl 1,4-cyclohexanedicarboxylate. The experimental results are shown in Table 5.

[0048] Table 5 Product analysis results of dimethyl terephthalate hydrogenation reaction

[0049]

[0050] Example 9

[0051] The 5.0wt% Ru / MnO2 catalyst prepared in Example 7 was applied to the catalytic hydrogenation reaction of aromatic ester substrates. 500mg of the above catalyst, 15mL of dimethyl 1,4-cyclohexanedicarboxylate and 19.35ml of dioctyl terephthalate were added to a high-pressure reactor. The stirring speed was 600rpm / min. The reaction was carried out at 4.0MPa H2 and 150°C for 4h. The conversion rate of the raw materials and the selectivity of the target product were analyzed by hydrogen nuclear magnetic resonance spectroscopy.

[0052] Table 6 Product analysis results of dioctyl terephthalate hydrogenation reaction

[0053]

[0054] Example 10

[0055] Cyclic Test of Ru / MnO2 Catalyst

[0056] The experiment was conducted in a high-pressure reactor, with 10 g of substrate dimethyl terephthalate, 37.5 mL of solvent dimethyl 1,4-cyclohexanedicarboxylate, and 0.50 g of the catalyst of Example 1 (Ru loading was 5%). The H2 pressure was set to 4.0 MPa, the reaction temperature was 150°C, and the stirring speed was 800 rpm / min. After the reaction was carried out for 5 hours, the converted product was taken out and analyzed by Agilent 8860 gas chromatograph to obtain the conversion rate of the raw material and the selectivity of the target product.

[0057] After each reaction, the catalyst was separated from the reaction solution by filtration, and the recovered catalyst was used in the next reaction. According to this method, the results of the cyclic experiment of repeated use of the catalyst are shown in Table 7.

[0058] Table 7 Cycle test of dimethyl terephthalate hydrogenation reaction

[0059]

[0060] As shown in Table 7, high conversion rate and high selectivity can be maintained during the five cycles, which lays a foundation for the large-scale promotion and use of the catalyst in the future.

[0061] The catalyst recovered after 5 cycles of the test in Example 10 was recorded as the Ru / MnO2 catalyst after the reaction.

[0062] The XRD comparison results of the unreduced Ru / MnO2 catalyst before the reaction in Example 1, the reduced Ru / MnO2 catalyst before the reaction, and the Ru / MnO2 catalyst after the reaction in Example 10 are shown in the table. Figure 2 In, from Figure 2 It can be seen from the XRD comparison of Ru / MnO2 catalyst before and after the reaction that there is no Ru peak before the reaction because Ru is dispersed very evenly and the Ru particles are very small and cannot be detected. There is a Ru peak after the reaction because the Ru particles increase in size after the reaction.

[0063] Performance Test:

[0064] The products (gas phase products and liquid phase products) obtained in Examples 2 to 9 were analyzed by gas chromatography, as shown in Table 8.

[0065] Table 8 Analysis results of dimethyl terephthalate hydrogenation reaction

[0066]

[0067]

[0068] It can be seen from Table 8 that the catalyst prepared in Example 1 is used for hydrogenation experiments, and in comparison between Example 2 and Example 3, dimethyl terephthalate has a higher conversion rate in DMCD solvent. It can be seen from Example 2 and Example 5 that in the selective hydrogenation experiment, the catalyst with a ruthenium loading of 5wt% is used for dimethyl terephthalate has a higher conversion rate.

[0069] The highly active and selective supported ruthenium-based catalyst prepared by the present invention is used for the selective hydrogenation reaction of aromatic esters. The active metal precursor and the carrier used in the present invention are both cheap and readily available, and the preparation method is simple and rapid. The catalyst in which a small amount of metallic ruthenium (1.0wt% to 5.0wt%) is loaded on a manganese dioxide carrier has excellent catalytic hydrogenation activity and selectivity for aromatic esters under mild conditions. The substrate has wide applicability and has good economic value and industrial application prospects.

[0070] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.

Claims

1. A supported ruthenium-based hydrogenation catalyst, characterized in that The catalyst comprises a carrier and an active component loaded on the carrier. The carrier is manganese dioxide, the active component is a metal ruthenium component, and the loading amount of the noble metal ruthenium element in the catalyst is 1.0-5.0 wt%.

2. A supported ruthenium-based hydrogenation catalyst as claimed in claim 1, characterized in that The specific surface area of ​​the manganese dioxide is between 100 and 200 m 2 / g.

3. The method for preparing a supported ruthenium-based hydrogenation catalyst according to claim 1, characterized in that The following steps are involved: 1) Dissolve the soluble metal salt of Ru in water to form a precursor aqueous solution, add manganese dioxide powder, and stir it thoroughly at 30-50°C to make the substances fully mixed; 2) Then, urea is added, and the mixture is stirred at 70°C to 110°C to deposit Ru metal on the surface of the carrier at high temperature, and the water is evaporated, washed, and dried to obtain a solid powder; 3) The solid powder obtained in step 2) is placed in a mixed atmosphere of H2 and N2 containing 5-30 v% H2 for calcination reduction, the reduction temperature is set to 300-500°C, and the reduction time is set to 2-6 h, to finally obtain the supported ruthenium-based hydrogenation catalyst.

4. The method for preparing a supported ruthenium-based hydrogenation catalyst as claimed in claim 3, characterized in that The stirring time in step 1) is 3-5h.

5. The method for preparing a supported ruthenium-based hydrogenation catalyst as claimed in claim 3, characterized in that In step 2), the stirring temperature is 80-90°C and the stirring time is 8-10h.

6. Use of a supported ruthenium-based hydrogenation catalyst as claimed in claim 1 in the selective hydrogenation reaction of aromatic ester compounds.

7. The use according to claim 6, characterized in that The aromatic ester compound is dimethyl terephthalate, dioctyl terephthalate or dibutyl terephthalate, and the benzene ring in the aromatic ester compound is hydrogenated and reduced to a 1,4-cyclohexane ring.

8. The use according to claim 7, characterized in that The supported ruthenium-based hydrogenation catalyst, solvent, and aromatic ester compound are mixed, and the reaction time is 2 to 8 hours at 130 to 160 ° C and a hydrogen pressure of 3 to 5.0 MPa. After the reaction is completed, the reactor is quickly cooled to room temperature to release the remaining hydrogen in the reactor. Finally, the reaction liquid and the catalyst are separated, and the catalyst is recovered to obtain the target product.

9. The use according to claim 8, characterized in that The mass of the catalyst is 5-20% of the mass of the aromatic ester compound.

10. The use according to claim 8, characterized in that The solvent is methanol or dimethyl 1,4-cyclohexanedicarboxylate, and the dispersion concentration of the aromatic ester compound in the solvent is 0.05-0.5 g / mL.

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