Hydrofining catalyst as well as preparation method and application thereof

Abstract

The invention provides a hydrofining catalyst as well as a preparation method and application thereof. The hydrofining catalyst has a core-shell structure, an inner core is a carrier, a shell is an active component loaded on the carrier, the carrier is a nickel carrier, and the active component comprises nickel and palladium. According to the hydrofining catalyst disclosed by the invention, two active metal sites Pd and Ni are loaded on the carrier, so that the conversion rate of 4-CBA can be effectively improved. The preparation method provided by the invention is simple in operation condition, Pd and Ni can be loaded on the carrier in an in-situ growth manner, the content of noble metal can be reduced, and the conversion rate of 4-CBA is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a hydrorefining catalyst and a preparation method and application thereof. Background Art

[0002] Purified Terephthalic Acid (PTA) is an important chemical raw material, which can be mainly used to produce polyester. Its preparation process mainly includes PX oxidation step and CTA hydrogenation refining step. The PX oxidation step is accompanied by a large number of side reactions, resulting in the crude terephthalic acid (CTA) obtained from the oxidation process containing by-products such as methylbenzaldehyde (TALD), p-methylbenzoic acid (PT acid) and p-carboxybenzaldehyde (4-carboxybenzaldehyde, 4-CBA). Among them, 4-CBA will have a great impact on the melting point of polyester and endanger the quality of the product. The content of 4-CBA is an important indicator of PTA quality, so 4-CBA must be removed through the CTA hydrogenation refining process. Since the molecular structure of 4-CBA is similar to that of terephthalic acid and it can form a eutectic with terephthalic acid, it is difficult to remove it by conventional physical methods. Therefore, in the CTA hydrorefining step, a CTA hydrorefining catalyst is used to catalyze the reaction, so that 4-CBA undergoes a reduction reaction with H2 under the action of the CTA hydrorefining catalyst, reducing its own aldehyde group to a methyl group, thereby generating a water-soluble substance PT acid and removing it.

[0003] However, the catalytic conversion effect of existing CTA hydrorefining catalysts on 4-CBA is not ideal, and the conversion rate of 4-CBA is low. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a hydrorefining catalyst and a preparation method and application thereof. The present invention loads Pd and Ni by in-situ growth on a nickel carrier, thereby effectively improving the conversion rate of 4-CBA.

[0005] In a first aspect, the present invention provides a hydrotreating catalyst having a core-shell structure, wherein the core is a carrier and the shell is an active component supported on the carrier, wherein the carrier is a nickel carrier and the active component includes nickel and palladium.

[0006] The hydrotreating catalyst of the present invention adopts a core-shell structure, wherein the core is a cheap transition metal Ni, and the shell is a composite structure of precious metal Pd and Ni, thereby preventing the precious metal Pd from being unable to participate in the reaction inside the catalyst. Meanwhile, the presence of the same element Ni in both the carrier and the active component is conducive to stable combination, improving the catalyst stability and extending the catalyst life.

[0007] In some embodiments, the carrier is a nano-branch structure. The nano-branch structure can expose more active sites to improve the utilization efficiency of the active component Pd.

[0008] In some embodiments, the mass of the active component Pd is 0.5-5wt% of the carrier, for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%.

[0009] In some embodiments, the mass of the active component Pd is 1 to 3 wt % of the carrier.

[0010] In some embodiments, the mass ratio of the active component Pd to the active component Ni is (0.05-0.5):1, for example, 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1. Ni in the above range can improve the dispersion and utilization of Pd. If the Pd content is too high, it may cause excessive Pd active centers or uneven dispersion due to excessive Pd content, thereby reducing the catalytic performance.

[0011] In some embodiments, the mass ratio of the active component Pd to the active component Ni is (0.1-0.5):1.

[0012] In a second aspect, the present invention provides a method for preparing a hydrotreating catalyst, comprising the following steps:

[0013] The mixed solution containing the carrier, the noble metal salt, the organic solvent and the auxiliary agent is pressurized by reducing gas and heated for reaction to obtain the hydrorefining catalyst.

[0014] In some embodiments, the noble metal salt comprises Pd and Ni active components.

[0015] In some embodiments, the noble metal salt is selected from a combination of nickel acetate and palladium acetate.

[0016] In some embodiments, the organic solvent is selected from one or more of dimethylformamide, acetone, perchloroethylene, triethanolamine, isopropanol, toluene or chloroform.

[0017] In some embodiments, the auxiliary agent is selected from one or more of oleylamine, sodium oleate or oleoyl monoethanol.

[0018] In some embodiments, the adjuvant is oleylamine.

[0019] In some embodiments, the reducing gas is selected from hydrogen and / or carbon monoxide.

[0020] In some embodiments, the reducing gas is carbon monoxide. Since hydrogen has too strong a reducing ability, it is easy to cause metal aggregation and uneven distribution on the support surface. Therefore, carbon monoxide with poor reducing ability is preferably used as the reducing gas during the in-situ growth process.

[0021] In some embodiments, the mass ratio of the active component Pd in ​​the precious metal salt to the second auxiliary agent is 1:5 to 1:20; for example, 1:5, 1:7, 1:9, 1:11, 1:13, 1:15, 1:17, 1:20.

[0022] In some embodiments, the mass ratio of the active component Ni to the component Pd in ​​the precious metal salt is (0.05-0.5):1, for example, 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1.

[0023] In some embodiments, the mass ratio of the active component Pd to the component Ni in the precious metal salt is (0.1-0.5):1.

[0024] In some embodiments, the preparation method of the carrier is as follows:

[0025] A nickel salt, a first organic solvent and a first auxiliary agent are mixed to obtain a first mixed solution; the first mixed solution is pressurized with a first reducing gas and heated for reaction to obtain the carrier.

[0026] In some embodiments, the nickel salt is selected from one or more of nickel acetate, nickel formate, nickel acetylacetonate, nickelocene, and nickel di-n-butyldithiocarbamate.

[0027] In some embodiments, the first organic solvent is selected from one or more of ethanol, methanol, propanol, isopropanol, and n-butanol.

[0028] In some embodiments, the first auxiliary agent is one or more of oleylamine, sodium oleate, and oleoyl monoethanol.

[0029] In some embodiments, the first adjuvant is sodium oleate.

[0030] In some embodiments, the first reducing gas is hydrogen and / or carbon monoxide.

[0031] In some embodiments, the first reducing gas is hydrogen.

[0032] In some embodiments, the mass ratio of the nickel salt to the first auxiliary agent is (0.1-3):10, for example, 0.1:10, 0.5:10, 1:10, 1.5:10, 2:10, 2.5:10, or 3:10.

[0033] In some embodiments, in preparing the carrier and preparing the hydrogenation catalyst, the pressurized pressure is 1 to 3 MPa, for example, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa.

[0034] In some embodiments, in preparing the carrier and preparing the hydrogenation catalyst, the temperature of the heating reaction is 140-200°C, for example, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C.

[0035] In a third aspect, the present invention provides an application of the hydrorefining catalyst described in the first aspect or the hydrogenation catalyst prepared by the preparation method described in the second aspect in catalyzing a 4-CBA conversion reaction.

[0036] In some embodiments, the temperature of the 4-CBA conversion reaction is 200-250°C, for example, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C.

[0037] In some embodiments, the pressure of the 4-CBA conversion reaction is 10 to 15 bar, for example, 10 bar, 11 bar, 12 bar, 13 bar, 14 bar, or 15 bar.

[0038] In some embodiments, the 4-CBA conversion reaction takes 120 to 130 min, for example, 120 min, 122 min, 124 min, 126 min, 128 min, or 130 min.

[0039] In a fourth aspect, the present invention provides a use of the hydrorefining catalyst described in the first aspect or the hydrogenation catalyst prepared by the preparation method described in the second aspect in the preparation of purified terephthalic acid.

[0040] The hydrofining catalyst of the present invention adopts a nickel carrier as a kernel, and two active metal sites of Pd and Ni are loaded on the carrier kernel as a shell. The core-shell structure in the present invention is relatively cheap transition metal Ni inside, and the composite structure of precious metal Pd and Ni outside, which not only has a strong hydrogenation effect, but also improves the dispersion and utilization of Pd, and avoids the precious metal Pd from being unable to participate in the reaction inside the catalyst, and the carrier and the active component all have the presence of the same element Ni, which is conducive to the stable combination of the carrier and the active component. The catalyst in the present invention can effectively improve the conversion rate of 4-CBA and the preparation method provided has simple operating conditions, can load Pd and Ni by in-situ growth on the carrier, can control Pd to be enriched in the catalyst outer layer, and improve the utilization rate of Pd. The precious metal content can be reduced to effectively reduce the catalyst cost, and the conversion rate of 4-CBA can be effectively improved. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to constitute any limitation of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present disclosure. Such structures and technologies are also described in many publications.

[0042] Example 1

[0043] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0044] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 2.12 g nickel acetate tetrahydrate, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water for 3 times respectively.

[0045] Example 2

[0046] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0047] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 2.12 g nickel acetate tetrahydrate, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use H2 to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water for 3 times respectively.

[0048] Example 3

[0049] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of oleylamine to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0050] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 2.12 g nickel acetate tetrahydrate, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL sodium oleate into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water for 3 times respectively.

[0051] Example 4

[0052] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0053] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 2.12 g nickel acetate tetrahydrate, 0.51 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water for 3 times respectively.

[0054] Example 5

[0055] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0056] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 1.8 g nickel acetate tetrahydrate, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water for 3 times respectively.

[0057] Example 6

[0058] In situ growth of Pd and Ni: (1) Add nickel foam, 2.12 g nickel acetate tetrahydrate, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water three times respectively.

[0059] Example 7

[0060] In situ growth of Pd and Ni: (1) Add carbon cloth, 2.12 g nickel acetate tetrahydrate, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water three times respectively.

[0061] Example 8

[0062] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 100 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0063] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 2.12 g nickel acetate tetrahydrate, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water for 3 times respectively.

[0064] Example 9

[0065] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0066] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 2.12 g nickel acetate tetrahydrate, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 180 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water for 3 times respectively.

[0067] Example 10

[0068] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 1 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0069] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 2.12 g nickel acetate tetrahydrate, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water for 3 times respectively.

[0070] Embodiment 11

[0071] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0072] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 2.12 g nickel acetate tetrahydrate, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 2 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water for 3 times respectively.

[0073] Comparative Example 1

[0074] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0075] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 0.21 g palladium acetate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 ml ethanol and deionized water for 3 times respectively.

[0076] Comparative Example 2

[0077] Preparation of nano-Ni carrier: (1) Add 40.12 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0078] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 5 mL of dimethylformamide, and 20 mL of oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL of ethanol and deionized water three times respectively.

[0079] Comparative Example 3

[0080] Preparation of nano-Ni carrier: (1) Add 38 g of nickel acetate tetrahydrate to 500 mL of anhydrous ethanol and stir thoroughly for 3 h until completely dissolved; (2) Add 300 mL of sodium oleate to the solution and stir thoroughly for 2 h; (3) Transfer the above solution to a dynamic reactor, pressurize it to 2 MPa with hydrogen and react at 160 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni carrier with 20 mL of ethanol and deionized water three times respectively.

[0081] In situ growth of Pd and Ni: (1) Add the prepared Ni support, 2.12 g nickel acetate tetrahydrate, 5 mL dimethylformamide, and 20 mL oleylamine into a beaker and stir thoroughly for 4 h; (2) Transfer the above solution to a reactor; (3) Use CO to pressurize to 1 MPa and react at 140 °C for 5 h; (4) Cool down and release the pressure, and wash the prepared nano-Ni support with 30 mL ethanol and deionized water for 3 times respectively.

[0082] Catalyst Evaluation:

[0083] The catalysts in the above examples and comparative examples are applied to catalyze the 4-CBA conversion reaction, and the specific steps include:

[0084] 0.5 g of catalyst, 48 mL of deionized water, and 12 mL of 4-CBA were added to a 100 mL dynamic pressure reactor. The reactor was purged with nitrogen and pressurized to 10 bar. After the temperature was raised to 200 ° C, hydrogen was introduced and the reaction time was 2 h. After the reaction was completed, the conversion rate of 4-CBA was detected by chromatographic analysis, as shown in Table 1.

[0085] Table 1

[0086]

[0087]

[0088] According to Table 1, Example 2 uses hydrogen as the reducing gas when preparing the nickel carrier. Since hydrogen has too strong a reducing ability, it easily causes metal aggregation and uneven distribution on the carrier surface. Therefore, the conversion rate of Example 2 is lower than that of Example 1.

[0089] Since sodium oleate is more likely to make the nickel carrier into a nano-branch structure than oleylamine during the preparation of the nickel carrier, the nano-branch structure can expose more active sites to improve the utilization efficiency of the active component Pd. Therefore, the conversion rate of Example 3 is reduced.

[0090] Since the catalytic performance has reached more than 99% in Example 1, increasing the Pd content in Example 4 does not have much effect on the catalytic performance. The present invention can effectively reduce the amount of Pd used, and can still achieve a good catalytic effect when the amount of Pd used is low.

[0091] Example 6 uses nickel foam as a carrier. Since nickel foam does not have the nano-dendritic structure of the nickel carrier in the present invention, during the in-situ growth process, most of the Pd will be covered by the outer layers of Pd and Ni, and the Pd sites cannot be well exposed, resulting in too low utilization of Pd. Therefore, the conversion rate of Example 6 is significantly lower than that of Example 1.

[0092] Example 7 uses carbon cloth as a carrier. Since the carbon cloth has a pore structure, the active component Pd will enter the pores and cannot participate in the catalyst reaction. It will also limit the orderly growth of Pd and Ni, causing most of the Pd to be covered inside the catalyst, reducing the dispersion and utilization of Pd. Therefore, the conversion rate of Example 7 is significantly lower than that of Example 1.

[0093] In Example 8, the temperature during the preparation of the Ni carrier is too low, which is not conducive to the formation of a nano-dendritic structure, so the catalytic performance is reduced and the conversion rate is lower than that of Example 1.

[0094] In Example 9, the temperature was too high during the in-situ growth process, resulting in too fast reduction and deposition of Pd and Ni, which were easily agglomerated and resulted in overly large grains, thus causing the catalyst performance to decline and the conversion rate to be lower than that of Example 1.

[0095] Example 10: Changing the pressure during the preparation of the nano-Ni carrier. If the pressure is too low, Ni reduction will be slow during the preparation of the Ni carrier, resulting in its slow growth and easy aggregation, which is not conducive to the formation of more branched structures.

[0096] Example 11: Changing the pressure during the in-situ growth process. Increasing the pressure results in too fast reduction and deposition of Pd and Ni during in-situ growth, which easily leads to overly large grains. When the pressure is appropriate, the growth will be more in line with the surface of the carrier.

[0097] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A hydrorefining catalyst having a core-shell structure, wherein the core is a carrier and the shell is an active component supported on the carrier, wherein the carrier is a nickel carrier and the active component includes nickel and palladium.

2. The hydrotreating catalyst according to claim 1, characterized in that The carrier is a nano-branch structure; and / or the mass of the active component Pd is 0.5-5wt% of the carrier; and / or the mass ratio of the active component Pd to the active component Ni is (0.05-0.5):

1.

3. A method for preparing a hydrotreating catalyst, comprising the following steps: The mixed solution containing the carrier, the noble metal salt, the organic solvent and the auxiliary agent is pressurized by reducing gas and heated for reaction to obtain the hydrorefining catalyst.

4. The preparation method according to claim 3, characterized in that: The noble metal salt comprises Pd and Ni active components; preferably selected from a combination of nickel acetate and palladium acetate; and / or, the organic solvent is selected from one or more of dimethylformamide, acetone, perchloroethylene, triethanolamine, isopropanol, toluene or chloroform; And / or, the auxiliary agent is selected from one or more of oleylamine, sodium oleate or oleyl monoethanol; preferably oleylamine; And / or, the reducing gas is selected from hydrogen and / or carbon monoxide, preferably carbon monoxide.

5. The preparation method according to claim 3 or 4, characterized in that: The mass ratio of the active component Pd in ​​the noble metal salt to the auxiliary agent is 1:5 to 1:20; And / or, the mass ratio of the active component Pd to the active component Ni in the noble metal salt is (0.05-0.5):

1.

6. The preparation method according to any one of claims 3 to 5, characterized in that: The preparation method of the carrier is as follows: Mixing a nickel salt, a first organic solvent and a first auxiliary agent to obtain a first mixed solution; pressurizing the first mixed solution with a first reducing gas and performing a heating reaction to obtain the carrier; Preferably, the nickel salt is selected from one or more of nickel acetate, nickel formate, nickel acetylacetonate, nickelocene, and nickel di-n-butyldithiocarbamate; and / or, the first organic solvent is selected from one or more of ethanol, methanol, propanol, isopropanol, and n-butanol; And / or, the first auxiliary agent is one or more of oleylamine, sodium oleate, and oleyl monoethanol; preferably sodium oleate; And / or, the first reducing gas is hydrogen and / or carbon monoxide; preferably hydrogen.

7. The preparation method according to any one of claim 6, characterized in that The mass ratio of the nickel salt to the first auxiliary agent is (0.1-3):

10.

8. The preparation method according to any one of claims 3 to 7, characterized in that: The pressurized pressure is 1-3 MPa; And / or, the temperature of the heating reaction is 140-200°C.

9. Use of the hydrotreating catalyst according to claim 1 or the hydrogenation catalyst prepared by the preparation method according to any one of claims 2 to 8 in catalyzing 4-CBA conversion reaction.

10. Use of the hydrorefining catalyst according to claim 1 or the hydrogenation catalyst prepared by the preparation method according to any one of claims 2 to 8 in the preparation of purified terephthalic acid.

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