Catalysts for the hydrogenation refining of crude terephthalic acid, their preparation methods and applications

Abstract

This invention discloses a catalyst for the hydrogenation refining of crude terephthalic acid, its preparation method, and its application. The catalyst comprises a support and an active component; wherein the active component is palladium metal and ruthenium metal, and the weight ratio of palladium metal to ruthenium metal is (3-10):1; wherein the valence state of the palladium metal is Pd. 0 The valence states of the ruthenium metal include Ru. 0 and Ru 4+ The catalyst provided by this invention has outstanding anti-sintering properties and is used in the hydrogenation refining reaction of crude terephthalic acid. While ensuring catalytic performance, it also has the characteristics of high thermal stability.

Description

Technical Field

[0001] This invention relates to catalysts for the hydrogenation refining of crude terephthalic acid, their preparation methods, and applications. Background Technology

[0002] Purified terephthalic acid, commonly known as PTA, is a basic raw material for the synthesis of polyethylene terephthalate (PET). Supported palladium / carbon catalysts are suitable for the purification of crude terephthalic acid. Impurities such as p-carboxybenzaldehyde (4-CBA) in crude terephthalic acid are hydrogenated to other compounds, which are then separated and purified by crystallization. Because palladium / carbon catalysts use a single active component, the distribution of palladium on the support has a significant impact on catalyst performance.

[0003] Because the hydrogenation refining of terephthalic acid is a first-order reaction with a rapid reaction rate, reactants have difficulty penetrating into the interior of the catalyst particles to react. This means that the active metal inside the particles, due to steric hindrance, cannot contact larger reactant molecules and thus cannot function effectively. In this case, the active metal on the outer surface exhibits high catalytic activity. To fully utilize precious metals, palladium / carbon catalysts are typically made in an eggshell shape, meaning the active component, palladium, is primarily supported on the surface of the support. The larger the surface area of ​​palladium in contact with the reactants, the better the activity. Catalysts with an eggshell-shaped active component distribution have higher hydrogenation catalytic capacity than catalysts with a wider distribution range. The hydrogenation refining of terephthalic acid is typically carried out at a reaction pressure of 6.5–8.5 MPa and a reaction temperature of 250–290 °C. Palladium grain growth is unavoidable in this process. Under normal reaction conditions, catalyst deactivation is primarily due to palladium grain growth. Commercially deactivated palladium-carbon catalysts for terephthalic acid hydrogenation exhibit palladium grains exceeding 20 nm, while fresh catalysts have palladium grains between 2 and 5 nm. In industrial applications, the faster the palladium grain growth, the shorter the catalyst's normal lifespan. This shortened catalyst lifespan not only wastes expensive palladium-carbon catalysts but also results in significant economic losses for the plant due to catalyst replacement. Patent US4,892,972 describes the use of a Pd / C and Rh / C bilayer catalyst with a Pd to Rh ratio of 10:1 for the hydrogenation refining of crude terephthalic acid. The results showed a significant improvement in catalyst lifetime and reduced Rh crystal growth. However, Rh is ten times more expensive than Pd, making it impractical. Other methods employ Pd and Ru bimetallic catalysts. Using activated carbon as a support, palladium can be easily reduced to elemental Pd with common chemical reducing agents such as formic acid, sodium formate, and hydrazine hydrate. However, Ru is not easily and completely reduced to elemental Ru; complete reduction with hydrogen at high temperature for over 8 hours is required. Using titanium dioxide as a support and hydrazine hydrate as a reducing agent, palladium and ruthenium can be reduced to elemental Pd and Ru, respectively. However, these supports have poor acid and alkali resistance and are unsuitable for PTA hydrogenation refining. Summary of the Invention

[0004] One of the technical problems this invention aims to solve is the low conversion rate and poor thermal stability of the catalyst in the existing technology for the hydrogenation refining reaction of crude terephthalic acid. This invention provides a new catalyst for the hydrogenation refining of crude terephthalic acid. This catalyst exhibits outstanding anti-sintering properties and, while ensuring catalytic performance, also possesses high thermal stability in the hydrogenation refining reaction of crude terephthalic acid.

[0005] The second technical problem to be solved by the present invention is the preparation method of the catalyst as described in the first technical problem above.

[0006] The third technical problem to be solved by the present invention is the application of the catalyst described in the above-mentioned technical problem one in the hydrogenation refining reaction of crude terephthalic acid.

[0007] To solve one of the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A catalyst for the hydrogenation refining of crude terephthalic acid, the catalyst comprising a support and an active component; wherein the active component is palladium metal and ruthenium metal, and the weight ratio of palladium metal to ruthenium metal is (3-10):1;

[0009] The palladium metal in question is in the valence state of Pd. 0 The valence states of the ruthenium metal include Ru. 0 and Ru 4+ .

[0010] In the above technical solution, Ru in the catalyst 4+ With Ru 0 The weight ratio is 0.1 to 1.0, preferably 0.2 to 0.8.

[0011] In the above technical solution, the mass ratio of palladium to ruthenium in the active component of the catalyst is preferably (3-6):1.

[0012] In the above technical solution, the active component accounts for 0.3% to 1% of the mass fraction of the catalyst.

[0013] In the above technical solution, the carrier is activated carbon.

[0014] In the above technical solution, the activated carbon is preferably at least one of coal-based carbon, wood-based carbon, or fruit shell carbon.

[0015] In the above technical solution, the fruit shell charcoal is preferably coconut shell charcoal.

[0016] In the above technical solution, the specific surface area of ​​the coconut shell charcoal is 800-1600 m². 2 / g, with a pore volume of 0.35~0.80mL / g.

[0017] To solve the second technical problem mentioned above, the present invention adopts the following technical solution: The catalyst preparation method described in the technical solution for the first technical problem mentioned above includes the following steps:

[0018] (1) Pretreatment of activated carbon to obtain catalyst support;

[0019] (2) Mix the active metal, alkylamine and solvent to obtain catalyst precursor i;

[0020] (3) The catalyst support from step (1) is mixed with the catalyst precursor i from step (2), aged, desolventized, and heat-treated to obtain catalyst precursor ii;

[0021] (4) Reduce the catalyst precursor ii from step (3) with a reducing agent, and heat treat it to obtain the catalyst.

[0022] In the above technical solution, the pretreatment in step (1) includes washing and drying; wherein washing is done with water, and the volume ratio of water to activated carbon is (2-10):1; the drying conditions are a temperature of 100-130℃ and a time of 4-8h.

[0023] In the above technical solution, the alkyl group in the alkylamine in step (2) is a straight-chain alkyl group, selected from C3 to C20, preferably from C12 to C18.

[0024] In the above technical solution, the active metals in step (2) are palladium and ruthenium; wherein the palladium source and ruthenium source are palladium salts and ruthenium salts. The palladium salt is selected from at least one of palladium nitrate, palladium acetate, chloropalladium acid and its salts, and dichlorotetraamminepalladium, preferably palladium acetate. The ruthenium salt is selected from at least one of ruthenium nitrate, ruthenium acetate, and ruthenium trichloride, preferably ruthenium acetate. The solvent is a conventional organic solvent in the art, such as at least one of diethyl ether, dimethyl ether, ethanol, isopropanol, and acetone, preferably diethyl ether.

[0025] In the above technical solution, in step (2), the mass ratio of the solvent, alkylamine and active metal is (5000~30000):(20~50):(5~20); wherein, the mass ratio of palladium and ruthenium in the active metal is (3~6):1.

[0026] In the above technical solution, the mass ratio of the catalyst support in step (1) to the catalyst precursor i in step (2) is 1:(2~5).

[0027] In the above technical solution, the aging time in step (3) is preferably 2 to 24 hours; the solvent removal adopts the evaporation and condensation recovery method, and the evaporation temperature is preferably 60 to 90 degrees Celsius; the heat treatment conditions are 150 to 250 degrees Celsius under an inert atmosphere for 2 to 8 hours, and the inert atmosphere is a nitrogen atmosphere or an inert gas atmosphere, preferably a nitrogen atmosphere.

[0028] In the above technical solution, the reducing agent in step (4) is selected from at least one of hydrogen, hydrazine hydrate, formaldehyde formic acid, formaldehyde or formate, preferably hydrazine hydrate.

[0029] In the above technical solution, the mass ratio of hydrazine hydrate to catalyst precursor ii in step (4) is 1:(2~10).

[0030] In the above technical solution, the operating conditions for heat treatment in step (4) are 300-500℃ for 8 hours under an inert atmosphere, wherein the inert atmosphere is a nitrogen atmosphere or an inert gas atmosphere, preferably a nitrogen atmosphere.

[0031] To solve the third technical problem mentioned above, the present invention adopts the following technical solution: the application of the catalyst described in the technical solution for one of the technical problems mentioned above in the hydrogenation refining reaction of crude terephthalic acid.

[0032] In the above technical solution, the application is to perform a hydrogenation purification reaction on crude terephthalic acid in the presence of the catalyst to obtain purified terephthalic acid.

[0033] In the above technical solution, the reaction conditions for the application are a reaction temperature of 250-350℃, preferably 270-290℃, and a reaction pressure of 6.5-8.5MPa.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) The catalyst for the hydrogenation refining of crude terephthalic acid provided by this invention was unexpectedly discovered by the inventors in a Pd and Ru catalyst supported on activated carbon, by controlling the Ru 4+ With Ru 0 When the weight ratio is within a specific range (0.1 to 1.0), a catalyst with good anti-sintering properties can be obtained.

[0036] (2) The preparation method of the crude terephthalic acid hydrogenation refining catalyst provided by the present invention is simple to operate. It involves mixing active metals and alkylamines, and by limiting the reduction conditions, it achieves effective control of Ru. 4+ With Ru 0 The above-mentioned catalyst for the hydrogenation refining of crude terephthalic acid was obtained by adjusting the weight ratio of the catalyst.

[0037] (3) The catalyst of the present invention is used in the hydrogenation refining reaction of crude terephthalic acid. While ensuring catalytic performance, it also has the characteristics of high heat resistance and stability, and has achieved outstanding technical results. Attached Figure Description

[0038] Figure 1 The Pd in ​​the catalyst prepared in Example 1 0 XPS map in the 3D region;

[0039] Figure 2 Ru in the catalyst prepared in Example 1 4+ XPS plot in region 3p. Detailed Implementation

[0040] The following examples will further illustrate the catalyst and its preparation method provided by the present invention, but the scope of protection of the present invention is not limited to these examples.

[0041] The Pd and Ru contents in the catalysts of the embodiments and comparative examples of this invention were determined by ICP-AES.

[0042] The contents of Pd and Ru in different valence states in the catalysts of the embodiments and comparative examples of this invention were analyzed by XPS using an ESCA-IAB MKⅡ photoelectron spectroscopy system. The laser source was MgKa rays (hv = 1486.6 eV), the operating voltage was 10 kV, and the X-ray current was 20 mA. Energy correction was performed using contaminated carbon C1s (Eb = 284.6 eV). Under these conditions, 461.5 eV (Ru3p3) / 2 ) for Ru 0 The corresponding characteristic peak, 465.2 eV (Ru3p) 3 / 2 ) for Ru +4 The corresponding characteristic peaks were analyzed using XPS Peakfit 4.1 software for Ru3p. 3 / 2 Peaks are fitted and decomposed before calculation.

[0043] The percentage content of ruthenium in different valence states was determined using XPS, and the calculation formula is as follows:

[0044]

[0045] x: Ru of the analyzed valence state; I: photoelectron peak area; n: number of different valence states in the Ru under consideration; S: sensitivity factor.

[0046] The thermal stability of the catalysts in the embodiments and comparative examples of the present invention was determined as follows:

[0047] The catalyst was calcined at 300℃, 400℃, and 500℃ for 8 hours under N2 protection, and then cooled to room temperature. The average grain size of palladium in the calcined catalyst was measured by X-ray diffraction (XRD) and calculated using the Debye-Scherrer formula.

[0048] Scherrer's formula: Dhkl = kλ / βcosθ, where Dhkl is the grain diameter along the direction perpendicular to the crystal plane (hkl), k is the Scherrer constant (usually 0.89), λ is the incident X-ray wavelength (Cuka wavelength is 0.15406 nm, Cuka1 wavelength is 0.15418 nm), θ is the Bragg diffraction angle (°), and β is the full width at half maximum (FWHM) of the diffraction peak (rad).

[0049] The thermal stability of a catalyst is represented by the grain size increase of the active component before and after calcination. A larger value indicates lower stability, and vice versa. The grain size increase is calculated as follows:

[0050] Grain enlargement rate = [(Average particle size of Pd after calcination - Average particle size of Pd in ​​fresh catalyst) / Average particle size of Pd in ​​fresh catalyst] × 100%.

[0051] In the embodiments and comparative examples of this invention, 4-CBA in the raw materials and products was analyzed by high performance liquid chromatography (HPLC). First, the sample to be analyzed was completely dissolved in ammonia water before analysis.

[0052] Catalyst activity evaluation conditions:

[0053] Reaction vessel: 2L stainless steel autoclave

[0054] Catalyst dosage: 2.0g

[0055] Crude terephthalic acid content: 30.0g (of which the content of 4-CBA is 10000ppmw)

[0056] Solvent: 1000mL pure water

[0057] Reaction pressure: 7.0 MPa

[0058] Hydrogen partial pressure: 0.5 MPa

[0059] Reaction time: 1.0 hour

[0060] Reaction temperature: 280℃

[0061]

[0062] The present invention will be further illustrated below through examples.

[0063]

Example 1

[0064] Weigh 100 grams of 4-8 mesh, sheet-like coconut shell activated carbon (specific surface area 1100 m²). 2 The catalyst support (with a pore volume of 0.52 mL / g) was washed with pure water at a volume ratio of 5:1 to pure water to activated carbon, and then dried at 130℃ for 8 hours to obtain the catalyst support.

[0065] Preparation of catalyst precursor: 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether was weighed and stirred for 30 min. The contents of Pd, Ru, and hexadecylamine were 1250 ppmw, 250 ppmw, and 1.0 wt%, respectively, to obtain catalyst precursor i. Then, 100 g of catalyst support was added to catalyst precursor i, with a mass ratio of catalyst support to catalyst precursor i of 1:4.1. The mixture was aged for 8 h, and then the diethyl ether was recovered by evaporation and condensation at 80 °C. The mixture was then heat-treated at 180 °C under a nitrogen atmosphere for 4 h and cooled to room temperature to obtain catalyst precursor ii. 200 g of hydrazine hydrate (20 wt%) was added to the above catalyst precursor ii, and reduction was carried out for 8 h. The mixture was then treated at 180 °C under a nitrogen atmosphere for 4 h and cooled to room temperature to obtain the desired catalyst. The thermal stability of the obtained catalyst was investigated by calcining at 300 °C, 400 °C, and 500 °C for 8 h under nitrogen protection.

[0066] The activity of the catalyst was evaluated, and the catalyst analysis data are listed in Table 1.

[0067]

Example 2

[0068] Weigh 100 grams of 4-8 mesh, sheet-like coconut shell activated carbon (specific surface area 1100 m²). 2 The catalyst support (with a pore volume of 0.52 ml / g) was washed with pure water at a volume ratio of 5:1 to pure water to activated carbon, and then dried at 130℃ for 8 hours to obtain the catalyst support.

[0069] Preparation of catalyst precursor: 400 g of a mixture of palladium acetate, ruthenium acetate, tetradecylamine, and diethyl ether was weighed and stirred for 30 min. The contents of Pd, Ru, and tetradecylamine were 1250 ppmw, 250 ppmw, and 1.0 wt%, respectively, to obtain catalyst precursor i. Then, 100 g of catalyst support was added to the catalyst precursor, and the mixture was mixed to obtain catalyst precursor i. The mass ratio of catalyst support to catalyst precursor i was 1:4.1. After aging for 8 h, the diethyl ether was evaporated and condensed at 80 °C to recover the precursor. Then, the precursor was heat-treated at 180 °C under a nitrogen atmosphere for 4 h and cooled to room temperature to obtain catalyst precursor ii. 200 g of hydrazine hydrate (20 wt%) was added to the above catalyst precursor ii, and the mixture was reduced for 8 h. Then, it was treated at 180 °C under a nitrogen atmosphere for 4 h and cooled to room temperature to obtain the desired catalyst. The thermal stability of the obtained catalyst was investigated by calcining at 300 °C, 400 °C, and 500 °C for 8 h under nitrogen protection.

[0070] The activity of the catalyst was evaluated, and the catalyst analysis data are listed in Table 1.

[0071]

Example 3

[0072] Weigh 100 grams of 4-8 mesh, sheet-like coconut shell activated carbon (specific surface area 1100 m²).2 The catalyst support (with a pore volume of 0.52 ml / g) was washed with pure water at a volume ratio of 5:1 to pure water to activated carbon, and then dried at 130℃ for 8 hours to obtain the catalyst support.

[0073] Preparation of catalyst precursor: Weigh 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether and stir for 30 min. The contents of Pd, Ru, and hexadecylamine are 1250 ppmw, 250 ppmw, and 1.0 wt%, respectively, to obtain the catalyst precursor. Then, add 100 g of catalyst support to the catalyst precursor and mix to obtain catalyst precursor i. The mass ratio of catalyst support to catalyst precursor i is 1:4.1. After aging for 6 h, the diethyl ether is evaporated and condensed at 80 °C to recover the ether. Then, the catalyst is heat-treated at 180 °C under a nitrogen atmosphere for 4 h and cooled to room temperature to obtain catalyst precursor ii. Add 200 g of hydrazine hydrate (concentration of 20 wt%) to the above catalyst precursor ii and reduce it for 8 h to obtain catalyst precursor iii. Treat the above catalyst precursor iii at 180 °C under a nitrogen atmosphere for 4 h and cool to room temperature to obtain the desired catalyst. The obtained catalyst was calcined at 300℃, 400℃, and 500℃ for 8 hours under nitrogen protection to investigate its thermal stability.

[0074] The activity of the catalyst was evaluated, and the catalyst analysis data are listed in Table 1.

[0075]

Example 4

[0076] Weigh 100 grams of 4-8 mesh, sheet-like coconut shell activated carbon (specific surface area 1100 m²). 2 The catalyst support (with a pore volume of 0.52 ml / g) was washed with pure water at a volume ratio of 5:1 to pure water to activated carbon, and then dried at 130℃ for 8 hours to obtain the catalyst support.

[0077] Preparation of catalyst precursor: Weigh 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether and stir for 30 min. The contents of Pd, Ru, and hexadecylamine are 1250 ppmw, 250 ppmw, and 1.0 wt%, respectively, to obtain the catalyst precursor. Then, add 100 g of catalyst support to the catalyst precursor and mix to obtain catalyst precursor i. The mass ratio of catalyst support to catalyst precursor i is 1:4.1. After aging for 8 h, the diethyl ether is evaporated and condensed at 80 °C to recover the ether. Then, the catalyst is heat-treated at 180 °C under a nitrogen atmosphere for 4 h and cooled to room temperature to obtain catalyst precursor ii. Add 200 g of hydrazine hydrate (concentration of 20 wt%) to the above catalyst precursor ii and reduce for 9 h to obtain catalyst precursor iii. Treat the above catalyst precursor iii at 180 °C under a nitrogen atmosphere for 4 h and cool to room temperature to obtain the desired catalyst. The obtained catalyst was calcined at 300℃, 400℃, and 500℃ for 8 hours under nitrogen protection to investigate its thermal stability.

[0078] The activity of the catalyst was evaluated, and the catalyst analysis data are listed in Table 1.

[0079] Comparative Example 1

[0080] Weigh 100 grams of 4-8 mesh, sheet-like coconut shell activated carbon (specific surface area 1100 m²). 2 The catalyst support (with a pore volume of 0.52 ml / g) was washed with pure water at a volume ratio of 5:1 to pure water to activated carbon, and then dried at 130℃ for 8 hours to obtain the catalyst support.

[0081] Preparation of catalyst precursor: 400 g of a mixture of palladium acetate, hexadecylamine, and diethyl ether was weighed and stirred for 30 min. The contents of Pd and hexadecylamine were 1250 ppmw and 1.0 wt%, respectively, to obtain the catalyst precursor. Then, 100 g of catalyst support was added to the catalyst precursor, and the mixture was mixed to obtain catalyst precursor i. The mass ratio of catalyst support to catalyst precursor i was 1:4.1. After aging for 8 h, the diethyl ether was evaporated and condensed at 80 °C to recover the precursor. Then, the precursor was heat-treated at 180 °C under a nitrogen atmosphere for 4 h and cooled to room temperature to obtain catalyst precursor ii. 200 g of hydrazine hydrate (concentration 20 wt%) was added to the above catalyst precursor ii and reduced for 8 h to obtain catalyst precursor iii. The above catalyst precursor iii was treated at 180 °C for 4 h under a nitrogen atmosphere and cooled to room temperature to obtain the desired catalyst. The thermal stability of the obtained catalyst was investigated by calcining at 300 °C, 400 °C, and 500 °C for 8 h under nitrogen protection.

[0082] The activity of the catalyst was evaluated, and the catalyst analysis data are listed in Table 1.

[0083] Comparative Example 2

[0084] Weigh 100 grams of 4-8 mesh, sheet-like coconut shell activated carbon (specific surface area 1100 m²). 2 The catalyst support (with a pore volume of 0.52 ml / g) was washed with pure water at a volume ratio of 5:1 to pure water to activated carbon, and then dried at 130℃ for 8 hours to obtain the catalyst support.

[0085] Preparation of catalyst precursor: 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether was weighed, with Pd, Ru, and hexadecylamine contents of 1250 ppmw, 250 ppmw, and 1.0 wt%, respectively. The mixture was stirred for 30 min to obtain the catalyst precursor. Then, 100 g of catalyst support was added to the catalyst precursor, and the mixture was mixed to obtain catalyst precursor i, with a mass ratio of catalyst support to catalyst precursor i of 1:4.1. The mixture was aged for 8 h, then the diethyl ether was evaporated and condensed at 80 °C to recover the precursor. The precursor was then heat-treated at 180 °C under a nitrogen atmosphere for 4 h and cooled to room temperature to obtain catalyst precursor ii. Catalyst precursor ii was reduced at 400 °C under a hydrogen atmosphere for 8 h and cooled to room temperature to obtain the desired catalyst. The thermal stability of the obtained catalyst was investigated by calcining at 300 °C, 400 °C, and 500 °C for 8 h under nitrogen protection.

[0086] The activity of the catalyst was evaluated, and the catalyst analysis data are listed in Table 1.

[0087] Comparative Example 3

[0088] Weigh 100 grams of 4-8 mesh, sheet-like coconut shell activated carbon (specific surface area 1100 m²). 2 The catalyst support (with a pore volume of 0.52 ml / g) was washed with pure water at a volume ratio of 5:1 to pure water to activated carbon, and then dried at 130℃ for 8 hours to obtain the catalyst support.

[0089] Preparation of catalyst precursor: Weigh 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether and stir for 30 min. The contents of Pd, Ru, and hexadecylamine are 1250 ppmw, 250 ppmw, and 1.0 wt%, respectively, to obtain the catalyst precursor. Then, add 100 g of catalyst support to the catalyst precursor and mix to obtain catalyst precursor i. The mass ratio of catalyst support to catalyst precursor i is 1:4.1. After aging for 8 h, the diethyl ether is evaporated and condensed at 80 °C to recover the ether. Then, it is heat-treated at 180 °C under a nitrogen atmosphere for 4 h and cooled to room temperature to obtain catalyst precursor ii. Add 200 g of hydrazine hydrate (concentration of 2 wt%) to the above catalyst precursor ii and reduce it for 4 h to obtain catalyst precursor iii. Treat the above catalyst precursor iii at 180 °C under a nitrogen atmosphere for 4 h and cool to room temperature to obtain the desired catalyst. The obtained catalyst was calcined at 300℃, 400℃, and 500℃ for 8 hours under nitrogen protection to investigate its thermal stability.

[0090] The activity of the catalyst was evaluated, and the catalyst analysis data are listed in Table 1.

[0091] Comparative Example 4

[0092] Weigh 100 grams of 4-8 mesh, sheet-like coconut shell activated carbon (specific surface area 1100 m²). 2 The catalyst support (with a pore volume of 0.52 ml / g) was washed with pure water at a volume ratio of 5:1 to pure water to activated carbon, and then dried at 130℃ for 8 hours to obtain the catalyst support.

[0093] Preparation of catalyst precursor: Weigh 400 g of a mixture of palladium acetate, ruthenium acetate, hexadecylamine, and diethyl ether and stir for 30 min. The contents of Pd, Ru, and hexadecylamine are 1250 ppmw, 250 ppmw, and 1.0 wt%, respectively, to obtain the catalyst precursor. Then, add 100 g of catalyst support to the catalyst precursor and mix to obtain catalyst precursor i. The mass ratio of catalyst support to catalyst precursor i is 1:4.1. After aging for 8 h, the diethyl ether is evaporated and condensed at 80 °C to recover the ether. Then, the catalyst is heat-treated at 180 °C under a nitrogen atmosphere for 4 h and cooled to room temperature to obtain catalyst precursor ii. Add 200 g of hydrazine hydrate (concentration of 20 wt%) to the above catalyst precursor ii and reduce it for 12 h to obtain catalyst precursor iii. Treat the above catalyst precursor iii at 180 °C under a nitrogen atmosphere for 4 h and cool to room temperature to obtain the desired catalyst. The obtained catalyst was calcined at 300℃, 400℃, and 500℃ for 8 hours under nitrogen protection to investigate its thermal stability.

[0094] The activity of the catalyst was evaluated, and the catalyst analysis data are listed in Table 1.

[0095] Table 1. Physicochemical properties and catalytic performance of catalysts in various examples and comparative examples.

[0096]

Claims

1. A catalyst for the hydrogenation refining of crude terephthalic acid, said catalyst comprising a support and an active component; wherein, The active components are palladium metal and ruthenium metal, and the weight ratio of palladium metal to ruthenium metal is (3~10):1; The palladium metal in question is in the valence state of Pd. 0 The valence states of the ruthenium metal include Ru. 0 and Ru 4+ Ru 4+ With Ru 0 The weight ratio is 0.1~1.

0.

2. The catalyst according to claim 1, characterized in that, In the catalyst, Ru 4+ With Ru 0 The weight ratio is 0.2~0.

8.

3. The catalyst according to claim 1, characterized in that, In the catalyst, the mass ratio of palladium to ruthenium in the active component is (3~6):

1.

4. The catalyst according to claim 1, characterized in that, In the catalyst, the active component accounts for 0.3% to 1% of the catalyst by mass.

5. The catalyst according to claim 1, characterized in that, The carrier is activated carbon.

6. The catalyst according to claim 5, characterized in that, The activated carbon is at least one of coal-based carbon, wood-based carbon, or fruit shell carbon.

7. The catalyst according to claim 6, characterized in that, The charcoal made from fruit shells is coconut shell charcoal.

8. The catalyst according to claim 7, characterized in that, The specific surface area of ​​the coconut shell charcoal is 800~1600 m². 2 / g, with a pore volume of 0.35~0.80mL / g.

9. A method for preparing the catalyst according to any one of claims 1-8, comprising the following steps: (1) Pretreatment of activated carbon to obtain catalyst support; (2) The active metal, alkylamine and solvent are mixed to obtain catalyst precursor i; (3) The catalyst support from step (1) is mixed with the catalyst precursor i from step (2), aged, desolventized, and heat-treated to obtain catalyst precursor ii; (4) Reduce the catalyst precursor ii from step (3) with a reducing agent, and heat treat it to obtain the catalyst.

10. The preparation method according to claim 9, characterized in that, The pretreatment in step (1) includes washing and drying; the washing is done with water, and the volume ratio of water to activated carbon is (2~10):1; the drying conditions are a temperature of 100~130℃ and a time of 4~8h.

11. The preparation method according to claim 9, characterized in that, The alkyl group in the alkylamine in step (2) is selected from one of C3 to C20.

12. The preparation method according to claim 9, characterized in that, The alkyl group in the alkylamine in step (2) is selected from one of C12 to C18.

13. The preparation method according to claim 9, characterized in that, The active metals mentioned in step (2) are palladium and ruthenium; wherein the palladium source and ruthenium source are palladium salt and ruthenium salt; the palladium salt is selected from at least one of palladium nitrate, palladium acetate, chloropalladium and its salts, and dichlorotetraamminepalladium; the ruthenium salt is selected from at least one of ruthenium nitrate, ruthenium acetate, and ruthenium trichloride.

14. The preparation method according to claim 13, characterized in that, The palladium salt mentioned in step (2) is selected from palladium acetate; the ruthenium salt is selected from ruthenium acetate.

15. The preparation method according to claim 9, characterized in that, In step (2), the mass ratio of the solvent, alkylamine and active metal is (5000~30000):(20~50):(5~20); wherein the mass ratio of palladium and ruthenium in the active metal is (3-6):

1.

16. The preparation method according to claim 9, characterized in that, The mass ratio of the catalyst support in step (1) to the catalyst precursor i in step (2) is 1:(2~5).

17. The preparation method according to claim 9, characterized in that, The aging time in step (3) is 2~24h; the solvent removal adopts the evaporation and condensation recovery method, and the evaporation temperature is 60~90℃; the heat treatment conditions are 150~250℃ treatment for 2~8h under an inert atmosphere, and the inert atmosphere is a nitrogen atmosphere or an inert gas atmosphere.

18. The preparation method according to claim 9, characterized in that, The reducing agent in step (4) is selected from at least one of hydrogen, hydrazine hydrate, formaldehyde, formaldehyde, or formate.

19. The preparation method according to claim 9, characterized in that, The reducing agent mentioned in step (4) is selected from hydrazine hydrate.

20. The preparation method according to claim 19, characterized in that, In step (4), the mass ratio of hydrazine hydrate to catalyst precursor ii is 1:(2~10).

21. The preparation method according to claim 9, characterized in that, The heat treatment conditions in step (4) are 300~500℃ under an inert atmosphere, and the inert atmosphere is a nitrogen atmosphere or an inert gas atmosphere.

22. The use of the catalyst according to any one of claims 1-8 in the hydrogenation refining reaction of crude terephthalic acid, wherein crude terephthalic acid is subjected to a hydrogenation refining reaction in the presence of said catalyst to obtain purified terephthalic acid.

23. The application according to claim 22, characterized in that, The reaction conditions for the application are a reaction temperature of 250~350℃ and a reaction pressure of 6.5~8.5MPa.

24. The application according to claim 22, characterized in that, The reaction conditions for the application are a reaction temperature of 270~290℃.

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