Ru-W-based composite catalyst as well as preparation method and application thereof

Abstract

The invention relates to the field of hydrogenation catalysts and discloses a Ru-W-based composite catalyst as well as a preparation method and application thereof. The Ru-W-based composite catalyst comprises a carrier, two main active components of metal ruthenium and metal tungsten are loaded on the carrier, and two auxiliaries of phosphorus element and metal nickel are also loaded on the carrier. The Ru-W-based composite catalyst provided by the invention can realize higher raw material conversion rate and trans-product selectivity in the process of preparing 1, 4-cyclohexanedicarboxylic acid by catalyzing terephthalic acid hydrogenation under the condition that high-price noble metals Pd and Pt are not used and the cost is reduced.

Description

Technical Field

[0001] The invention relates to the field of hydrogenation catalysts, and in particular to a Ru-W based composite catalyst and a preparation method and application thereof. Background Art

[0002] 1,4-Cyclohexanedicarboxylic acid (CHDA), molecular formula C8H 12 O4 is an aliphatic dibasic acid. CHDA has a symmetrical structure and has the characteristics of 1,4-substituents and alicyclic ring structures. It can give polyester resins for high-performance coatings and glass fiber reinforced plastics many unique properties and is an important raw material for the polymer industry. In addition, CHDA is also a raw material for the preparation of polyester monomer 1,4-cyclohexanedimethanol. In recent years, the global demand for high-performance materials has increased, driving the market demand for CHDA and its derivatives.

[0003] The process of preparing CHDA by hydrogenation reaction with terephthalic acid (PTA) as raw material is simple and is the main way to prepare CHDA at present. However, the existing PTA hydrogenation process for preparing CHDA often has the problems of low conversion rate and trans product selectivity. Since it is not easy to separate the raw material PTA and the product CHDA, it is difficult to achieve high product purity when the reaction conversion rate is low. In addition, CHDA is usually a mixture of cis and trans isomers. Trans CHDA is a white scaly columnar crystal with lower solubility in water than cis CHDA and a melting point greater than 300°C; cis CHDA is a white leaf crystal with considerable solubility in water and a melting point of 170-171°C. Since trans CHDA has a higher melting point than cis CHDA, the polyester produced from trans CHDA also has better performance. Therefore, when preparing CHDA, the ratio of trans and cis isomers of the product CHDA is very important.

[0004] When the precious metals Pd and Pt are used as active components in the catalyst, although a higher conversion rate and trans-CHDA selectivity can be achieved, this requires that the catalyst contains more Pd and Pt. When the Pd and Pt content in the catalyst is reduced, the conversion rate and trans-CHDA selectivity will drop significantly. The high prices of these two precious metals will lead to excessive catalyst costs. For example, patent CN105582926A uses a catalyst containing 10wt% Pd, 2.5wt% Pt, and 7.5wt% Zn to achieve a PTA conversion rate of 100% and a trans-CHDA selectivity of 82%. However, when the Pd content is reduced to 1wt%, the PTA content in the product liquid is as high as 56%, and the trans-1,4-CHDA content is reduced to 34%. Therefore, how to improve the PTA conversion rate and trans-CHDA selectivity without using the high-priced precious metals Pd and Pt is a major problem currently faced in the hydrogenation of PTA to CHDA. Summary of the invention

[0005] In order to solve the above technical problem, that is, the conversion rate and trans product selectivity of the PTA hydrogenation process to CHDA are low without using the relatively expensive precious metals Pd and Pt in the catalyst, the present invention provides a Ru-W-based composite catalyst and a preparation method and application thereof. The Ru-W-based composite catalyst can achieve a high raw material conversion rate and trans product selectivity in the process of catalyzing terephthalic acid hydrogenation to prepare 1,4-cyclohexanedicarboxylic acid without using the expensive precious metals Pd and Pt, thereby reducing the cost.

[0006] The specific technical scheme of the present invention is: In a first aspect, the present invention provides a Ru-W-based composite catalyst, comprising a carrier; the carrier is loaded with two main active components, metallic ruthenium and metallic tungsten, and is also loaded with two auxiliary agents, phosphorus and metallic nickel.

[0007] The catalyst of the present invention uses metal ruthenium (Ru) and metal tungsten (W) as main active components, and phosphorus (P) and nickel (Ni) as auxiliary agents. The four components cooperate with each other and can achieve a higher raw material conversion rate and trans product selectivity in the process of catalyzing terephthalic acid hydrogenation to prepare 1,4-cyclohexanedicarboxylic acid without using expensive precious metals Pd and Pt. Specifically: (1) The added metal tungsten forms a composite compound with metal ruthenium, which can regulate the size of ruthenium, inhibit the growth of ruthenium particles, and make the utilization rate of metal active components higher, thereby improving the conversion rate of terephthalic acid and the selectivity of trans-1,4-cyclohexanedicarboxylic acid.

[0008] (2) The present invention finds that, on the basis of using metal tungsten and metal ruthenium as the main active components, when metal nickel or phosphorus is used alone as an auxiliary agent, the selectivity of the trans product will be significantly reduced. However, when metal nickel and phosphorus are used as two auxiliary agents in combination, the two can synergistically change the electronic structure and acid sites on the catalyst surface, thereby improving the selectivity of trans-1,4-cyclohexanedicarboxylic acid.

[0009] Preferably, the carrier is a composite of fullerene and activated carbon in a mass ratio of 1:4 to 49.

[0010] Furthermore, the carrier is a composite of fullerene and activated carbon in a mass ratio of 1:9 to 19.

[0011] Under the catalyst system of the present invention, compared with using fullerene or activated carbon alone, using a composite of the two as a carrier can further improve the feedstock conversion rate and trans product selectivity in the process of catalyzing terephthalic acid hydrogenation to prepare 1,4-cyclohexanedicarboxylic acid. The reason is that the synergistic effect between fullerene and activated carbon can provide a stable carrier with a suitable composite pore structure, thereby improving the feedstock conversion rate and trans product selectivity.

[0012] In addition, the ratio between fullerene and activated carbon affects the PTA conversion rate and trans-1,4-CHDA selectivity. When the mass ratio between the two is controlled at 1:4-49, a higher PTA conversion rate and trans-1,4-CHDA selectivity can be achieved. On this basis, when the mass ratio is 1:9-19, the trans product selectivity can be further improved.

[0013] Preferably, in the Ru-W based composite catalyst, the content of metallic ruthenium is not less than 0.3wt%, the mass ratio of metallic ruthenium to metallic tungsten is 1:2-30, the total content of phosphorus element and metallic nickel is 6-20wt%, and the mass ratio of phosphorus element to metallic nickel is 1:1-5.

[0014] Furthermore, in the Ru-W based composite catalyst, the content of metal ruthenium is 0.3-2 wt%.

[0015] Furthermore, in the Ru-W based composite catalyst, the mass ratio between metal ruthenium and metal tungsten is 1:5-10.

[0016] Furthermore, in the Ru-W based composite catalyst, the mass ratio between phosphorus element and metallic nickel is 1:1-5.

[0017] In the catalyst of the present invention, the catalytic activity and reaction selectivity can be improved by increasing the content of metal ruthenium. When the content of metal ruthenium is 0.3wt% or more, the PTA hydrogenation reaction can achieve a higher conversion rate and trans-1,4-CHDA selectivity.

[0018] Among the two main active components, the content of tungsten metal relative to ruthenium metal (the mass ratio between the two) will affect the interaction effect between the two. When the mass ratio between ruthenium metal and tungsten metal is controlled in the range of 1:2 to 30, tungsten metal can be used to better inhibit the growth of ruthenium particles and avoid excessive coverage of ruthenium sites by tungsten, thereby achieving a higher PTA conversion rate and trans-1,4-CHDA selectivity. On this basis, when the mass ratio between ruthenium metal and tungsten metal is controlled in the range of 1:5 to 10, the PTA conversion rate and trans-1,4-CHDA selectivity can be further improved.

[0019] In addition, for the two additives, phosphorus and nickel, the ratio between the two will affect their synergistic effect. When the mass ratio between phosphorus and nickel is 1:1-5, the combination of phosphorus and nickel can effectively improve the PTA conversion rate and trans-1,4-CHDA selectivity compared to no additives. The more preferred mass ratio is 1:2-5.

[0020] Preferably, the phosphorus element exists in the Ru-W based composite catalyst in the form of phosphoric acid.

[0021] In a second aspect, the present invention provides a method for preparing the Ru-W based composite catalyst, comprising the following steps: dissolving a ruthenium source, a tungsten source, a phosphorus source and a nickel source in a solvent, adding a carrier, fully impregnating and drying, and then reducing the ruthenium source, the tungsten source and the nickel source to metallic ruthenium, metallic tungsten and metallic nickel to obtain the Ru-W based composite catalyst.

[0022] Preferably, the preparation step of the carrier includes: dispersing fullerene and activated carbon in a dispersion medium, reacting at 80-100° C. for 1-4 hours, separating a solid product, and obtaining the carrier (ie, a composite of fullerene and activated carbon).

[0023] Furthermore, the process of dispersing fullerene and activated carbon in a dispersion medium includes: dispersing fullerene in an organic solvent to obtain a fullerene dispersion; dispersing activated carbon in water to obtain an activated carbon dispersion; and mixing the fullerene dispersion and the activated carbon dispersion.

[0024] Furthermore, the mass ratio of the fullerene to the organic solvent is 1:15-30; the mass ratio of the activated carbon to water is 1:15-30.

[0025] Preferably, the ruthenium source, tungsten source, phosphorus source and nickel source are ruthenium trichloride, ammonium tungstate, phosphoric acid and nickel acetate respectively; in the process of reducing the ruthenium source, tungsten source and nickel source to metallic ruthenium, metallic tungsten and metallic nickel, the reducing agent used includes at least one of hydrazine hydrate, formaldehyde and hydrogen.

[0026] In a third aspect, the present invention provides the use of the Ru-W based composite catalyst in the preparation of 1,4-cyclohexanedicarboxylic acid by hydrogenation of terephthalic acid.

[0027] Preferably, the application comprises the following steps: using water as a reaction solvent, reacting terephthalic acid with hydrogen under the action of the Ru-W based composite catalyst, the reaction temperature is 100 to 250°C, the hydrogen pressure is 0.5 to 10 MPa, the reaction time is 0.5 to 4 hours, and the mass ratio of the Ru-W based composite catalyst to terephthalic acid is 1:1 to 50.

[0028] Furthermore, the reaction temperature is 130-200° C., the hydrogen pressure is 1-5 MPa, the reaction time is 0.5-2 h, and the mass ratio of the Ru-W based composite catalyst to terephthalic acid is 1:10-30.

[0029] Preferably, the mass ratio of terephthalic acid to reaction solvent is 1:1.5-19, more preferably 1:2-9.

[0030] In a fourth aspect, the present invention provides the use of the Ru-W based composite catalyst in improving the conversion rate of terephthalic acid hydrogenation reaction and the selectivity of trans-1,4-cyclohexanedicarboxylic acid.

[0031] Preferably, the application comprises the following steps: using water as a reaction solvent, reacting terephthalic acid with hydrogen under the action of the Ru-W based composite catalyst, the reaction temperature is 100 to 250°C, the hydrogen pressure is 0.5 to 10 MPa, the reaction time is 0.5 to 4 hours, and the mass ratio of the Ru-W based composite catalyst to terephthalic acid is 1:1 to 50.

[0032] Furthermore, the reaction temperature is 130-200° C., the hydrogen pressure is 1-5 MPa, the reaction time is 0.5-2 h, and the mass ratio of the Ru-W based composite catalyst to terephthalic acid is 1:10-30.

[0033] Compared with the prior art, the present invention has the following advantages: (1) In the catalyst of the present invention, metal ruthenium, metal tungsten, phosphorus and metal nickel are used in combination with each other, so that high raw material conversion rate and trans product selectivity can be achieved in the process of catalyzing terephthalic acid hydrogenation to prepare 1,4-cyclohexanedicarboxylic acid without using expensive precious metals Pd and Pt, thereby reducing costs.

[0034] (2) In the catalyst of the present invention, by using a composite of fullerene and activated carbon as a carrier, the raw material conversion rate and the trans product selectivity of the reaction of hydrogenating terephthalic acid to prepare 1,4-cyclohexanedicarboxylic acid can be further improved. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the embodiments.

[0036] Overall embodiment First, the present invention relates to a Ru-W-based composite catalyst, including a carrier; the carrier is loaded with two main active components, namely, metal ruthenium and metal tungsten, and is also loaded with two auxiliary agents, namely, phosphorus and metal nickel. In the above catalyst, the added metal tungsten forms a composite compound with metal ruthenium, which can regulate the size of ruthenium, inhibit the growth of ruthenium particles, and make the utilization rate of metal active components higher, thereby improving the conversion rate of terephthalic acid, and at the same time, improving the selectivity of trans-1,4-cyclohexanedicarboxylic acid; on the basis of using metal tungsten and metal ruthenium as the main active components, when using metal nickel and phosphorus as two auxiliary agents, the two can change the electronic structure and acid sites on the catalyst surface through synergistic action, thereby improving the selectivity of trans-1,4-cyclohexanedicarboxylic acid. Through the above-mentioned method, the present invention adopts the coordination of metal ruthenium, metal tungsten, phosphorus and metal nickel, and can achieve a higher raw material conversion rate and trans product selectivity in the process of catalyzing terephthalic acid hydrogenation to prepare 1,4-cyclohexanedicarboxylic acid without using high-priced precious metals Pd and Pt.

[0037] In some specific embodiments, the carrier is a composite of fullerene and activated carbon in a mass ratio of 1:4 to 49. In the catalyst system of the present invention, compared with using fullerene or activated carbon alone, using the composite of the two as a carrier can provide a stable carrier with a suitable composite pore structure through synergistic effect, thereby further improving the raw material conversion rate and trans product selectivity in the process of catalyzing terephthalic acid hydrogenation to prepare 1,4-cyclohexanedicarboxylic acid.

[0038] In some specific embodiments, in the Ru-W based composite catalyst, the content of metallic ruthenium is not less than 0.3wt%, the mass ratio of metallic ruthenium to metallic tungsten is 1:2-30, the total content of phosphorus element and metallic nickel is 6-20wt%, and the mass ratio of phosphorus element to metallic nickel is 1:1-5. By controlling the above parameters, the various components in the catalyst can be better coordinated with each other, thereby achieving a higher PTA conversion rate and trans-1,4-CHDA selectivity. Specifically: by increasing the content of metallic ruthenium, the catalytic activity and reaction selectivity can be improved; when the mass ratio between metallic ruthenium and metallic tungsten is controlled in the range of 1:2 to 30, metallic tungsten can be used to better inhibit the growth of ruthenium particles and avoid excessive coverage of ruthenium sites by tungsten, thereby achieving a higher PTA conversion rate and trans-1,4-CHDA selectivity; when the mass ratio between phosphorus and metallic nickel is 1:1 to 5, a better synergistic effect can be produced between the two, so that compared with no additives, the combination of phosphorus and metallic nickel can effectively improve the PTA conversion rate and trans-1,4-CHDA selectivity.

[0039] In some specific embodiments, the phosphorus element exists in the Ru-W based composite catalyst in the form of phosphoric acid.

[0040] Second, the present invention relates to a method for preparing the Ru-W based composite catalyst, comprising the following steps: dissolving a ruthenium source, a tungsten source, a phosphorus source and a nickel source in a solvent, adding a carrier, fully impregnating and drying, and then reducing the ruthenium source, tungsten source and nickel source to metallic ruthenium, metallic tungsten and metallic nickel to obtain the Ru-W based composite catalyst.

[0041] In some specific embodiments, the ruthenium source, tungsten source, phosphorus source and nickel source are ruthenium trichloride, ammonium tungstate, phosphoric acid and nickel acetate, respectively; in the process of reducing the ruthenium source, tungsten source and nickel source to metallic ruthenium, metallic tungsten and metallic nickel, the reducing agent used includes at least one of hydrazine hydrate, formaldehyde and hydrogen.

[0042] In some specific embodiments, the preparation step of the carrier includes: dispersing fullerene and activated carbon in a dispersion medium, reacting at 80-100°C for 1-4 hours, separating a solid product, and obtaining the carrier (i.e., a composite of fullerene and activated carbon). In this specific embodiment, optionally or preferably, the process of dispersing fullerene and activated carbon in a dispersion medium includes: dispersing fullerene in an organic solvent at a mass ratio of 1:15-30 to obtain a fullerene dispersion; dispersing activated carbon in water at a mass ratio of 1:15-30 to obtain an activated carbon dispersion; mixing the fullerene dispersion and the activated carbon dispersion. There is no particular limitation on the organic solvent used to disperse fullerenes. According to the understanding of those skilled in the art, any substance commonly used in the art can be used.

[0043] Thirdly, the present invention relates to the application of the Ru-W based composite catalyst in the preparation of 1,4-cyclohexanedicarboxylic acid by hydrogenation of terephthalic acid.

[0044] In some specific embodiments, the application includes the following steps: using water as the reaction solvent, reacting terephthalic acid with hydrogen under the action of the Ru-W based composite catalyst, the reaction temperature is 100-250°C, the hydrogen pressure is 0.5-10MPa, the reaction time is 0.5-4h, the mass ratio of the Ru-W based composite catalyst to terephthalic acid is 1:1-50, and the mass ratio of terephthalic acid to the reaction solvent is 1:1.5-19.

[0045] Fourthly, the present invention relates to the application of the Ru-W based composite catalyst in improving the conversion rate of terephthalic acid hydrogenation reaction and the selectivity of trans-1,4-cyclohexanedicarboxylic acid.

[0046] In some specific embodiments, the application includes the following steps: using water as the reaction solvent, reacting terephthalic acid with hydrogen under the action of the Ru-W based composite catalyst, the reaction temperature is 100-250°C, the hydrogen pressure is 0.5-10MPa, the reaction time is 0.5-4h, the mass ratio of the Ru-W based composite catalyst to terephthalic acid is 1:1-50, and the mass ratio of terephthalic acid to the reaction solvent is 1:1.5-19. Specific embodiments The present invention is described below by specific 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. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims and any equivalents thereof are the protection scope of the present invention.

[0048] In the following examples and comparative examples, the meanings of the abbreviations are as follows: PTA: terephthalic acid; CHDA: 1,4-cyclohexanedicarboxylic acid; CFU: Fullerene; AC: activated carbon; DMO: dimethyl oxalate.

[0049] Example 1: Preparation and application of catalyst According to the following steps, the catalyst of Example 1 was prepared and used to catalyze the hydrogenation reaction of PTA to prepare CHDA: (1) Preparation of CFU-AC composite carrier: Weigh CFU and AC in a mass ratio of 2:98, mix them with 20 times the mass of DMO and 20 times the mass of pure water, stir vigorously for 30 minutes, then mix the two dispersions obtained under stirring, and then transfer them to a hydrothermal kettle, react at 95°C for 3 hours, cool and centrifuge to obtain a solid, then wash it with anhydrous ethanol and pure water for 3 times respectively, filter, and place it in a 100°C oven to dry for 12 hours to obtain a CFU-AC composite carrier for standby use.

[0050] (2) Preparation of catalyst: According to the Ru element loading (content) of 0.5wt%, W element loading (content) of 5wt%, P element loading (content) of 1wt%, and Ni element loading (content) of 5wt%, the corresponding mass of ruthenium trichloride, ammonium tungstate, phosphoric acid and nickel acetate were weighed respectively and dissolved in pure water to obtain an impregnation solution. The obtained impregnation solution was mixed with the CFU-AC composite carrier, impregnated for 24h, and then dried in a vacuum drying oven at 100℃ for 12h to obtain a catalyst precursor. The catalyst precursor was reduced with 10vol% hydrogen and nitrogen mixed gas at 250℃ for 2h to obtain a Ru-W / P-Ni@CFU-AC catalyst product. According to ICP-AES analysis, the Pd content in the catalyst was 0.5wt%, the W content was 5wt%, the P content was 1wt%, and the Ni content was 5wt%.

[0051] (3) Application of catalyst: 200g of terephthalic acid was added to an autoclave, 10g of the catalyst prepared in the present embodiment was added respectively, 800g of water was added, stirring was started, nitrogen was introduced for replacement three times, hydrogen was introduced for replacement three times, hydrogen was introduced to raise the pressure to 2MPa and keep it stable, the reaction temperature was maintained at 160°C, and hydrogen was introduced continuously for reaction for 1.0h. The reaction product was analyzed by liquid chromatography, and the PTA conversion, the selectivity of cis- and trans-products, and the content of by-products in the reaction product were calculated, and the results are listed in Table 2. The by-product was a mixture of benzoic acid, p-toluic acid, and p-tolualdehyde.

[0052] Comparative Example 1: Effect of W, P, Ni and carrier composition on catalytic performance In Comparative Example 1, a catalyst was prepared according to the steps of Example 1 and used to catalyze the hydrogenation reaction of PTA to prepare CHDA. The only difference from Example 1 is that the catalyst does not carry W, P, or Ni, and the carrier does not contain CFU (the catalyst compositions of Example 1 and Comparative Example 1 are shown in Table 1). In Table 1, the mass ratio of CFU to AC in Comparative Example 1 is 0:100, indicating that the carrier is completely composed of AC and does not contain CFU.

[0053] In Comparative Example 1 and Example 1, the measured PTA conversion rate, selectivity of cis- and trans-products, and content of by-products in the reaction products are shown in Table 2.

[0054] Table 1 Catalyst composition Table 2 Catalyst performance test results It can be seen from Table 2 that compared with the AC seat catalyst loaded with Ru, the present invention can effectively improve the PTA conversion rate and trans-1,4-CHDA selectivity by using AC and CFU composite as a carrier to load Ru, W, P and Ni.

[0055] Comparative Examples 2-4 and Examples 2-4: Effect of Carrier on Catalytic Performance In Comparative Examples 2-4 and Examples 2-4, catalysts were prepared according to the steps of Example 1 and used to catalyze the hydrogenation reaction of PTA to prepare CHDA. The only difference from Example 1 was that the composition of the carrier was changed according to Table 3. In Table 3, the mass ratio of CFU to AC in Comparative Example 1 was 0:100, indicating that the carrier was completely composed of AC and did not contain CFU; the mass ratio of CFU to AC in Comparative Example 1 was 100:0, indicating that the carrier was completely composed of CFU and did not contain AC.

[0056] In Comparative Examples 2 to 4 and Examples 2 to 4, the measured PTA conversion rate, the selectivity of cis- and trans-products, and the content of by-products in the reaction products are shown in Table 4.

[0057] Table 3 Catalyst composition Table 4 Catalyst performance test results It can be seen from Table 4 that compared with using CFU or AC as a carrier alone, a composite of the two in a certain ratio (mass ratio 1:9-49) can achieve a higher PTA conversion rate and trans-1,4-CHDA selectivity. Moreover, on this basis, when the mass ratio of CFU to AC is 1:4-49, the PTA conversion rate and trans-1,4-CHDA selectivity can be further improved, and more preferably 1:9-19 (which can improve the trans product selectivity to a greater extent). The reason is speculated to be that the synergistic effect between fullerene and activated carbon can provide a stable carrier with a suitable composite pore structure, thereby improving the raw material conversion rate and trans product selectivity.

[0058] Comparative Examples 5-7 and Examples 5-10: Effect of the Composition of the Main Active Components on Catalytic Performance In Comparative Examples 5-7 and Examples 5-10, catalysts were prepared according to the steps of Example 2 and used to catalyze the hydrogenation reaction of PTA to prepare CHDA. The only difference from Example 2 was that the content of Ru or W in the catalyst was changed according to Table 5.

[0059] In Comparative Examples 5 to 7 and Examples 5 to 10, the measured PTA conversion rate, the selectivity of cis- and trans-products, and the content of by-products in the reaction products are shown in Table 6.

[0060] Table 5 Catalyst composition Table 6 Catalyst performance test results From Table 6 we can see that: (1) In the catalyst, by increasing the Ru content, the PTA conversion rate and trans-1,4-CHDA selectivity can be increased. When the Ru content is 0.3wt% or more, the PTA conversion rate can reach 100% and the trans-1,4-CHDA selectivity can reach 80% or more.

[0061] (2) In the catalyst, when the content of tungsten metal relative to ruthenium metal is too low or too high, it will have an adverse effect on the PTA conversion rate and trans-1,4-CHDA selectivity; when the mass ratio of ruthenium metal to tungsten metal is 1:2-30, a higher PTA conversion rate and trans-1,4-CHDA selectivity can be achieved, and the more preferred mass ratio is 1:5-10. The reason is speculated to be that when the content of tungsten metal relative to ruthenium metal is too low, tungsten metal cannot be used to inhibit the growth of ruthenium particles; when the content of tungsten metal relative to ruthenium metal is too high, tungsten metal will over-cover the ruthenium sites in the catalyst.

[0062] Comparative Examples 8-12 and Examples 11-15: Effect of the composition of the additive on the catalytic performance In Comparative Examples 8 to 12 and Examples 11 to 15, catalysts were prepared according to the steps of Example 2 and used to catalyze the hydrogenation reaction of PTA to prepare CHDA. The only difference from Example 2 was that the content of P or Ni in the catalyst was changed according to Table 7.

[0063] In Comparative Examples 8 to 12 and Examples 11 to 15, the measured PTA conversion rate, the selectivity of cis- and trans-products, and the content of by-products in the reaction products are shown in Table 8.

[0064] Table 7 Catalyst composition Table 8 Catalyst performance test results It can be seen from Table 8 that in the catalyst of the present invention, compared with no auxiliary agent (Comparative Example 8), when only one of the auxiliary agents P and Ni is loaded (Comparative Examples 9 and 10), the selectivity of trans-1,4-CHDA decreases, but when P and Ni are used in a certain ratio (mass ratio of 1:1 to 5) and loaded in the catalyst together (Examples 2, 11 to 15), the selectivity of trans-1,4-CHDA can be improved. It is speculated that the reason is that the added auxiliary metal nickel and non-metallic phosphorus can change the electronic structure and acid sites of the catalyst surface through synergistic effects at a certain ratio, thereby improving the selectivity of trans-1,4-cyclohexanedicarboxylic acid.

[0065] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment in the field and can be obtained from conventional commercial channels; unless otherwise specified, the methods used in the present invention are conventional methods in the field.

[0066] 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 falls within the protection scope of the technical solution of the present invention.

Claims

1. A Ru-W based composite catalyst, characterized in that: The invention comprises a carrier; the carrier is loaded with two main active components, namely metal ruthenium and metal tungsten, and is also loaded with two auxiliary agents, namely phosphorus element and metal nickel.

2. The Ru-W based composite catalyst according to claim 1, characterized in that The carrier is a composite of fullerene and activated carbon in a mass ratio of 1:4-49.

3. The Ru-W based composite catalyst according to claim 1, characterized in that In the Ru-W based composite catalyst, the content of metal ruthenium is not less than 0.3wt%, the mass ratio of metal ruthenium to metal tungsten is 1:2-30, the total content of phosphorus element and metal nickel is 6-20wt%, and the mass ratio of phosphorus element to metal nickel is 1:1-5.

4. The Ru-W based composite catalyst according to claim 1 or 3, characterized in that: The phosphorus element exists in the Ru-W based composite catalyst in the form of phosphoric acid.

5. A method for preparing the Ru-W based composite catalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: The ruthenium source, tungsten source, phosphorus source and nickel source are dissolved in a solvent, added to a carrier, fully impregnated and then dried, and then the ruthenium source, tungsten source and nickel source are reduced to metallic ruthenium, metallic tungsten and metallic nickel to obtain the Ru-W based composite catalyst.

6. The preparation method according to claim 5, characterized in that: The preparation steps of the carrier include: dispersing fullerene and activated carbon in a dispersion medium, reacting at 80-100° C. for 1-4 hours, separating a solid product, and obtaining the carrier.

7. The preparation method according to claim 5, characterized in that: The ruthenium source, tungsten source, phosphorus source and nickel source are ruthenium trichloride, ammonium tungstate, phosphoric acid and nickel acetate respectively; in the process of reducing the ruthenium source, tungsten source and nickel source to metallic ruthenium, metallic tungsten and metallic nickel, the reducing agent used includes at least one of hydrazine hydrate, formaldehyde and hydrogen.

8. Use of the Ru-W based composite catalyst according to any one of claims 1 to 4 in the preparation of 1,4-cyclohexanedicarboxylic acid by hydrogenation of terephthalic acid.

9. The use according to claim 8, characterized in that: The method comprises the following steps: using water as a reaction solvent, reacting terephthalic acid with hydrogen under the action of the Ru-W based composite catalyst, the reaction temperature is 100-250°C, the hydrogen pressure is 0.5-10MPa, the reaction time is 0.5-4h, and the mass ratio of the Ru-W based composite catalyst to terephthalic acid is 1:1-50.

10. Use of the Ru-W based composite catalyst according to any one of claims 1 to 4 in improving the conversion rate of terephthalic acid hydrogenation reaction and the selectivity of trans-1,4-cyclohexanedicarboxylic acid.

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