Supported catalyst, and preparation method therefor and use thereof

Abstract

The present invention provides a supported catalyst, and a preparation method therefor and the use thereof. The catalyst comprises: a modified carbon material having an oxygen-containing functional group, a covering agent and palladium, wherein ID1 / IG=0.1-1.2. The catalyst of the present invention can significantly improve the catalytic efficiency of a palladium-carbon catalyst, and can effectively reduce the residual amount of 4-CBA in a terephthalic acid hydrofining reaction.

Description

A supported catalyst, its preparation method and application Technical Field

[0001] This invention relates to the field of supported catalyst technology, and particularly to a supported catalyst for the hydrogenation purification of terephthalic acid, its preparation method and application. This invention also relates to a composition for preparing the catalyst and its preparation method. Background Technology

[0002] Purified terephthalic acid (PTA) is a major raw material for polyester production, and its demand has been increasing in recent years. Improving PTA product quality and reducing raw material consumption are of great significance to industrial production. PTA production mainly employs the air oxidation process with p-xylene. Although the product undergoes separation and purification after the oxidation reaction, a large amount of impurity 4-CBA (p-carboxybenzaldehyde) remains. To reduce the impurity content, further purification is required by reacting 4-CBA with hydrogen in the presence of a catalyst. Palladium-on-carbon catalyst is currently the most widely used catalyst for the hydrogenation purification of crude terephthalic acid.

[0003] US Patent 6066589A discloses a hydrogenation catalyst in which palladium is supported on activated carbon, wherein less than 50% of the Pd is supported in a surface layer of less than 50 μm on the support surface, and the remaining palladium is located in a surface layer of 50-400 μm. Patent CN104549241A discloses a terephthalic acid hydrogenation refining catalyst, using activated carbon as a support, with a palladium mass percentage of 0.20-1.0%, wherein 70-85% of the palladium is distributed in a surface layer of 0.2-20 μm, no more than 10% of the palladium is distributed in a surface layer of 0-0.20 μm on the support, and the remaining palladium is distributed in an inner layer of 20-180 μm.

[0004] However, existing catalysts suffer from severe palladium loss and low hydrogenation efficiency. Therefore, developing highly efficient catalysts is currently a research hotspot. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a supported catalyst, its preparation method and application. This invention also relates to a composition for preparing the catalyst, which can be used for the hydrogenation purification of terephthalic acid.

[0006] In a first aspect, the present invention provides a supported catalyst comprising a modified carbon material support having oxygen-containing functional groups, palladium, and a capping agent, wherein I D1 / I G =0.1-1.2.

[0007] Here about I D1 / I GThe meaning is explained as follows: Typically, the Raman spectrum of the catalyst, which reflects the surface properties of the modified carbon material with oxygen-containing functional groups, contains five peaks, corresponding to 1346.2 ± 10 cm⁻¹. -1 1582.8±10cm -1 1200.5±10cm -1 1499.4±10cm -1 and 1616.4±10cm -1 1346.2±10cm -1 Corresponding to sp in aromatic rings 2 The vibrational peak of carbon, D1, is 1582.8 ± 10 cm⁻¹. -1 The position corresponds to sp in the aromatic ring 2 E of in-phase tensile vibration in the carbon domain 2g The peak G of the first-order scattering mode. The ratio of the area of ​​peak D1 to the area of ​​peak G is I. D1 / I G This I can serve as a basis for understanding the surface defects of the carbon material. D1 / I G This indicates that the graphitization degree of the carbon material is significantly reduced during the loading process, introducing more defects or heteroatom functional groups, providing adsorption sites for the metal and a protective covering effect. Preferably, I D1 / I G =0.2-1.1, more preferably I D1 / I G =0.2-1.0, for example, I D1 / I G =0.21.

[0008] In the catalyst of the present invention, the covering agent may be present on the surface of the support.

[0009] For example, in some embodiments, the Raman spectrum of the catalyst of the present invention contains a wavelength of 2400-2500 cm⁻¹. -1 The peak at 2600-2700cm -1 The sharp peaks at these points represent vibrational peaks between CH groups in different functional groups. These peaks demonstrate the presence of the covering agent on the carrier surface.

[0010] For example, the catalyst of the present invention begins to lose weight rapidly after 200°C in a nitrogen atmosphere, and loses 4-10% by mass based on the total mass of the catalyst at 800°C. For example, about 8% by mass. This illustrates the removal of the surface coating agent of the catalyst at high temperatures, and also demonstrates the presence of relevant sites during catalyst loading.

[0011] In some embodiments, the catalyst of the present invention is in the form of a coexistence of atomic-level distribution and nanoclusters. The clusters do not contain lattice striations, i.e., the clusters are amorphous particles. This form of catalyst facilitates the exposure of active sites of Pd, while the atoms are less likely to ripen and agglomerate into particles under the promotion of cluster hydrogen spillover. For example, the catalyst of the present invention contains Pd clusters ≤2.2 nm, such as about 2 nm, while also having Pd with a single atomic point distribution.

[0012] For example, the catalyst of the present invention is a palladium-supported palladium-carbon catalyst.

[0013] Preferably, the covering agent is selected from compounds having the structures shown in Formula I, Formula II and Formula III:

[0014] Wherein, R1, R2, R3, R4, and R5 are each independently selected from hydrogen, deuterium, halogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 heteroalkyl, -NH2, -OH, substituted or unsubstituted amino, acyl, carbonyl, hydroxyl, or ester group having 1-10 carbon atoms; the substituents are selected from deuterium, halogen, C1-C10 straight-chain or branched alkyl, C3-C10 cycloalkyl, C6-C20 aryl, -NH2, C1-C10 alkyl-substituted amino or C3-C20 heteroaryl, and the number of substituents is selected from an integer between 1 and 10;

[0015] n is 1 or 2;

[0016] X is C or N.

[0017] Preferably, in the catalyst of the present invention, the Pd content is 0.05-0.7% by mass, more preferably 0.05-0.5% by mass, and even more preferably 0.1-0.5% by mass.

[0018] In some embodiments, the covering agent has at least one of the following physical parameters: (1) a surface tension of 20-60 dyne / cm; for example, 20 dyne / cm, 25 dyne / cm, 30 dyne / cm, 35 dyne / cm, 40 dyne / cm, 45 dyne / cm, 50 dyne / cm, 55 dyne / cm, 60 dyne / cm or any value between them; (2) a polarizability of the covering agent > 7 (10 - 24 cm 3 ).

[0019] Surface tension test: The test standard is ASTM D1331-2014.

[0020] Polarizability testing: The polarizability of pure substances is known and can be found in existing technologies. For complex mixtures, the electric field-induced second harmonic generation (EFISH) method can be used: by comparing the SHG intensity of the sample solution with that of a standard substance (such as p-nitroaniline), and combining parameters such as the concentration-dependent dielectric constant, coherence length, and refractive index, the polarizability of the molecules can be calculated.

[0021] In some embodiments, the covering agent has at least one of the following physical parameters: (1) surface tension 25-35 dyne / cm; (2) polarizability 9.5-12 (10 -24 cm 3 For example, 9.5 (10) -24 cm 3 ), 9.8 (10 -24 cm 3 ),10.1(10 -24 cm 3 ), 10.4(10 - 24 cm 3 ), 10.7 (10 -24 cm 3 ),11(10 -24 cm 3 ), 11.3 (10 -24 cm 3 ), 11.7 (10 - 24 cm 3 ), 12(10 -24 cm 3 ) or any value between them.

[0022] In some embodiments, R1, R2, R3, R4, and R5 are each independently selected from hydrogen, deuterium, halogen, substituted or unsubstituted C1-C10 alkyl, -NH2, -OH, substituted or unsubstituted amino groups having 1-10 carbon atoms, and hydroxyl groups; the substituents are selected from deuterium, halogen, C1-C10 straight-chain or branched alkyl, -NH2, or C1-C10 alkyl-substituted amino groups, and the number of substituents is selected from an integer between 1 and 5.

[0023] In some embodiments, R1, R2, R3, R4, and R5 are each independently selected from hydrogen, deuterium, F, Cl, Br, methyl, ethyl, propyl, butyl, or -NH2.

[0024] In some embodiments, R1, R2, R3, R4, and R5 are each independently selected from hydrogen, deuterium, methyl, ethyl, propyl, or butyl.

[0025] In some embodiments, the covering agent includes one or more of γ-methylpyridine, 2-methyltetrahydrofuran, tetrahydrofuran, N-methylpyrrolidone, 1-butyl-2-pyrrolidone, and 2-pyrrolidone.

[0026] In some embodiments, the covering agent comprises γ-methylpyridine and / or 2-methyltetrahydrofuran.

[0027] In the modified carbon material having oxygen-containing functional groups, the oxygen-containing functional groups are, for example, one or more of COOH, COH, COC, and C=O, preferably COOH and COH, and preferably the mass ratio of COOH to COH is ≥1:1. When COOH is present, the mass ratio of oxygen in the COOH surface functional groups to the total mass of oxygen in the catalyst is preferably 20-35%, more preferably 23-34%, for example 30%.

[0028] In some embodiments, the modified carbon material with oxygen-containing functional groups exhibits infrared spectra at 2900±50 cm⁻¹. -1 It has a peak, while ordinary carbon materials do not.

[0029] The modified carbon material with oxygen-containing functional groups can be prepared by the following method, which includes mixing and reacting carbon material, polyol and pH adjuster.

[0030] An oxidation reaction can occur between carbon materials and polyols, which functionalizes the surface of the carbon materials, making them rich in oxygen-containing functional groups (such as glycolic acid carboxyl groups), providing highly dispersed sites for subsequent Pd loading.

[0031] In some embodiments, the carbon material is selected from one or more of carbon nanotubes, carbon nanofibers, and / or activated carbon, wherein the activated carbon is preferably coconut shell carbon.

[0032] In some embodiments, the carbon material is carbon nanotubes. The surface of carbon nanotubes is easy to modify and functionalize, and their electron transport properties are beneficial for subsequent catalytic reactions.

[0033] In some embodiments, the aspect ratio of the carbon nanotubes is 125-12500, for example, 150, 550, 1070, 2500, 4200, 6100, 8000, 9500, 10500, 12000 or any value between them.

[0034] In some embodiments, the outer diameter of the carbon nanotubes is 8-80 nm, for example, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm or any value between them.

[0035] In some embodiments, the polyol is selected from one or more of ethylene glycol, propylene glycol, and / or glycerol.

[0036] In some embodiments, the pH adjuster is selected from urea and ammonia, preferably urea.

[0037] In some embodiments, the mass ratio of the polyol to the carbon material is 5-20:1; for example, 5:1, 7:1, 9:1, 11:1, 13:1, 15:1, 17:1, or 19:1. Within this range, abundant functionalized oxygen-containing functional groups can be formed on the surface of the carbon material.

[0038] In some embodiments, the mass ratio of the polyol to the pH adjuster is 200-50:1, for example, 200:1, 180:1, 160:1, 140:1, 120:1, 100:1, 80:1, or 60:1.

[0039] In some embodiments, the reaction temperature is 100-150°C, for example 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C.

[0040] In some embodiments, the reaction pressure is 0.5-1.5 MPa, for example 0.5 MPa, 0.7 MPa, 0.9 MPa, 1.1 MPa, 1.3 MPa, or 1.5 MPa.

[0041] In some embodiments, the reaction is carried out in a hydrothermal reactor.

[0042] In some embodiments, the reaction time is 1-8 hours, for example 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours.

[0043] In some embodiments, the reaction is carried out in an air atmosphere.

[0044] In a second aspect, the present invention provides a method for preparing the above-mentioned supported catalyst, wherein,

[0045] The preparation method includes the following steps:

[0046] (1) A modified carbon material carrier with oxygen-containing functional groups is treated with a first covering agent to obtain material A; (2) Material A is treated with an aqueous solution of palladium precursor to obtain material B;

[0047] or

[0048] The preparation method includes the following steps: (1') treating the modified carbon material with oxygen-containing functional groups with a first covering agent to obtain material A'; (2') treating material A' with an aqueous solution of palladium precursor to obtain material B'; (3') treating material B' with a second covering agent to obtain material C';

[0049] Then, material B or C' is reduced to obtain a supported catalyst.

[0050] The first covering agent and / or the second covering agent may be selected as described above.

[0051] Preferably, the first covering agent and / or the second covering agent are selected from compounds having the structures shown in Formula I, Formula II and Formula III above.

[0052] In some embodiments, the first covering agent and the second covering agent may be the same.

[0053] In some embodiments, the first covering agent can be a more hydrophobic covering agent, such as a monoketone structure (i.e., a structure in which the carbonyl group is not bonded to a heteroatom) covering agent (e.g., cyclohexanone) and a furan covering agent (e.g., 2-methyltetrahydrofuran), while the second covering agent can be a more hydrophilic covering agent, such as a pyrrolidone covering agent (e.g., N-methylpyrrolidone (NMP)) and a pyridine covering agent, to increase the stability of the catalyst. Here, monoketone covering agents have the best hydrophobicity; for example, cyclohexanone is essentially insoluble in water due to its symmetrical structure. Furan covering agents have high relative hydrophobicity, where the heteroatom oxygen can form hydrogen bonds with water and is slightly miscible, while the increased number of methyl terminals enhances the hydrophobic effect. Among pyridine covering agents, some covering agents are miscible with water. Pyrrolidones generally have the best hydrophilicity and are miscible with water in any proportion.

[0054] The modified carbon material support with oxygen-containing functional groups can be selected as described above for the supported catalyst product of the present invention.

[0055] In some embodiments, the aqueous palladium precursor is selected from one or more of aqueous chloropalladium, aqueous tetraaminopalladium nitrate, and / or aqueous palladium acetate.

[0056] In some embodiments, the pH of the aqueous palladium precursor solution is 0.1-5, for example 0.1, 1, 2, 3, 4, 5.

[0057] In some embodiments, the pH of the aqueous palladium precursor solution is adjusted using hydrochloric acid and / or nitric acid.

[0058] In some embodiments, the reducing agent used in the reduction treatment is one or more of sodium formate solution, formic acid, and hydrazine hydrate.

[0059] In some embodiments, the amount of the reducing agent is 1-10% of the mass of the carrier, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0060] In some embodiments, the reduction treatment temperature is 50-120°C, for example 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, or 115°C.

[0061] In some implementations, the reduction process takes 0.5-3 hours, for example, 1 hour, 1.5 hours, 2 hours, or 2.5 hours.

[0062] In a third aspect, the present invention provides the application of the supported catalyst described in the first aspect or the supported catalyst prepared by the preparation method described in the second aspect in hydrogenation reactions, particularly in the hydrogenation purification of terephthalic acid.

[0063] In a fourth aspect, the present invention provides a method for hydrogenating and purifying terephthalic acid, comprising: using crude terephthalic acid containing 4-CBA and hydrogen as raw materials, and reacting in the presence of the supported catalyst described in the first aspect or the supported catalyst prepared by the preparation method described in the second aspect.

[0064] In some embodiments, the pressure of the hydrogen gas is 0.1-1 MPa; for example, 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.7 MPa, or 0.9 MPa.

[0065] In some embodiments, the reaction temperature is 100-150°C, for example 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C.

[0066] In some embodiments, the reaction time is 20-40 min, preferably 25-35 min.

[0067] In a fifth aspect, the present invention provides a composition for preparing the above-described supported catalyst of the present invention, comprising a modified carbon material support having oxygen-containing functional groups, a covering agent, and an aqueous solution of a palladium precursor.

[0068] The covering agent may be selected as described for the supported catalyst products of the present invention, and is preferably selected from compounds having the structures shown in Formula I, Formula II and Formula III above.

[0069] The modified carbon material support with oxygen-containing functional groups can be selected as described above for the supported catalyst product of the present invention.

[0070] The aqueous palladium precursor can be selected as described above for the method of preparing the supported catalyst of the present invention.

[0071] In a sixth aspect, the present invention provides a method for preparing the above-described composition for preparing the supported catalyst of the present invention, the method comprising the following steps:

[0072] (1) A modified carbon material carrier with oxygen-containing functional groups is treated with a first covering agent to obtain material A; (2) Material A is treated with an aqueous solution of palladium precursor to obtain material B, i.e., the composition.

[0073] or

[0074] The preparation method includes the following steps: (1') treating a modified carbon material with oxygen-containing functional groups with a first covering agent to obtain material A'; (2') treating material A' with an aqueous solution of palladium precursor to obtain material B'; (3') treating material B' with a second covering agent to obtain material C', i.e., the composition.

[0075] The first covering agent and / or the second covering agent may be selected as described above.

[0076] Preferably, the first covering agent and / or the second covering agent are selected from compounds having the structures shown in Formula I, Formula II and Formula III above.

[0077] In some implementations, the first covering agent and the second covering agent are the same.

[0078] The modified carbon material support with oxygen-containing functional groups can be selected as described above for the catalyst product of the present invention.

[0079] The aqueous palladium precursor can be selected as described above for the method of preparing the supported catalyst of the present invention.

[0080] This invention can significantly improve the dispersibility of the catalyst by treating it with a covering agent, thereby improving the catalytic efficiency of the catalyst. In the hydrogenation refining reaction of terephthalic acid, it can effectively reduce the residual amount of 4-CBA, improve the anchoring of Pd, and reduce the metal loss rate. Attached Figure Description

[0081] Figure 1 shows the Raman spectra of the catalyst products of Example 1 and Comparative Example 1, illustrating that Raman scattering is significantly correlated with the electronic structure of carbon materials, at 671 cm⁻¹. -1 And 1040cm - 1 The signal peak corresponding to Pd metal.

[0082] Figure 2 shows the thermogravimetric data of the catalysts of Example 1 and Comparative Example 1.

[0083] Figure 3 shows the HAADF-STEM image of the catalyst of Example 1, where a bright spot (within a circle) represents a Pd atom.

[0084] Figure 4 shows the HAADF-STEM image of the catalyst in Comparative Example 1, where the catalyst mainly exists in the form of larger Pd nanocrystals.

[0085] Figure 5 shows a schematic diagram of one embodiment of the catalyst preparation method of the present invention. Detailed Implementation

[0086] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0087] Unless otherwise specified, all reagents used in this invention can be purchased commercially or prepared by the methods described herein. The carbon nanotubes used in the embodiments and comparative examples of this invention were purchased from the Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, with aspect ratios of 125-12500 and outer diameters of 8-80 nm.

[0088] The testing method of this invention is as follows:

[0089] The Pd content was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) using an Agilent 725-ES ICP-AES instrument. The catalyst described in this invention was dissolved in aqua regia and hydrofluoric acid. After evaporating the acid solution and diluting, multiple measurements were performed, and the average value was taken to obtain the average Pd content (mass percentage).

[0090] Raman spectroscopy testing: Instrument model: InViaReflex, Renishaw. Excitation source: Ar ion laser (30mW), wavelength: 523nm, scanning precision: 2cm. -1 The scanning range is 1000-3000cm. -1 .

[0091] Infrared spectroscopy testing: Instrument model: Nicolet 6700. Routine infrared testing was performed using KBr pellets, with a wavenumber range of 4000-400 cm⁻¹. -1 The resolution is 4cm-1.

[0092] The mass ratio of oxygen in the functional groups on the COOH surface to the total mass of oxygen in the catalyst was measured and analyzed using X-ray photoelectron spectroscopy (XPS) on a Kratos AXIS SUPRA instrument equipped with an Al target emitting Kα rays (1486.6 eV, excitation voltage 15 kV). The binding energy of the measured elements was corrected using the C1s peak at 284.8 eV as a reference. The Pd orbital was measured as 3d, with a scan interval of 0.1 eV.

[0093] Example 1

[0094] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-1.

[0095] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of 2-methyltetrahydrofuran dropwise to A-1 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-1 and stir for 30 min; finally add 4.5 g of 2-methyltetrahydrofuran and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and record it as B-1.

[0096] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-1.

[0097] In the Raman spectrum of catalyst C-1, I was measured D1 / I G =0.21.

[0098] In the Raman spectrum of catalyst C-1, there is a 2434 cm⁻¹ -1 The peak at that location, and 2670cm -1 The peak at that point (see Figure 1).

[0099] The catalyst C-1 underwent a weight loss experiment at 800°C, and the weight loss was approximately 8% by mass (see Figure 2).

[0100] The catalyst C-1 contains Pd clusters of approximately 2 nm in size, along with Pd atoms distributed as individual atomic points (see Figure 3, where a bright spot (in a circle) represents a Pd atom).

[0101] In catalyst C-1, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0102] The preparation conditions are listed in Table 1.

[0103] Example 2

[0104] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-2.

[0105] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of cyclohexanone dropwise to A-2 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-2 and stir for 30 min; finally add 4.5 g of cyclohexanone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and record it as B-2.

[0106] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-2.

[0107] In the Raman spectrum of the catalyst C-2, I was measured D1 / I G =0.28.

[0108] In the Raman spectrum of catalyst C-2, there is a 2437 cm⁻¹ -1 The peak at that location, and 2667cm -1 The sharp peak at that location.

[0109] In catalyst C-2, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0110] The preparation conditions are listed in Table 1.

[0111] Example 3

[0112] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-3.

[0113] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of tetrahydrofuran dropwise to A-3 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-3 and stir for 30 min; finally add 4.5 g of tetrahydrofuran and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and record it as B-3.

[0114] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-3.

[0115] In the Raman spectrum of the catalyst C-3, I was measured D1 / I G =0.24.

[0116] In the Raman spectrum of catalyst C-3, there is a 2440 cm⁻¹... -1 The peak at that location, and 2668cm -1 The sharp peak at that location.

[0117] In catalyst C-3, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst. The preparation conditions are listed in Table 1.

[0118] Example 4

[0119] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-4.

[0120] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of 2-methyltetrahydrofuran dropwise to A-4 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-4 and stir for 30 min; finally add 4.5 g of cyclohexanone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-4.

[0121] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-4.

[0122] In the Raman spectrum of catalyst C-4, I was measured D1 / I G =0.88.

[0123] In the Raman spectrum of catalyst C-4, there is a 2436 cm⁻¹. -1 The peak at that location, and 2668cm -1 The sharp peak at that location.

[0124] In catalyst C-4, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0125] The preparation conditions are listed in Table 1.

[0126] Example 5

[0127] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-5.

[0128] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of cyclohexanone dropwise to A-5 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-5 and stir for 30 min; finally add 4.5 g of 2-methyltetrahydrofuran, and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-5.

[0129] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-5.

[0130] In the Raman spectrum of catalyst C-5, I was measured D1 / I G =0.79.

[0131] In the Raman spectrum of catalyst C-5, there is a 2440 cm⁻¹ -1 The peak at that location, and 2666cm -1 The sharp peak at that location.

[0132] In catalyst C-5, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0133] The preparation conditions are listed in Table 1.

[0134] Example 6

[0135] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-6.

[0136] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of 2-methyltetrahydrofuran dropwise to A-6 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-6 and stir for 30 min; finally add 4.5 g of tetrahydrofuran and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-6.

[0137] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-6.

[0138] In the Raman spectrum of catalyst C-6, I was measured D1 / I G =0.35.

[0139] In the Raman spectrum of catalyst C-6, there is a 2435 cm⁻¹... -1 The peak at that location, and 2667cm -1 The sharp peak at that location.

[0140] In catalyst C-6, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0141] The preparation conditions are listed in Table 1.

[0142] Example 7

[0143] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-7.

[0144] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of 2-methyltetrahydrofuran dropwise to A-7 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-7 and stir for 30 min; finally add 4.5 g of N-methylpyrrolidone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-7.

[0145] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-7.

[0146] In the Raman spectrum of catalyst C-7, I was measured D1 / I G =0.21.

[0147] The Raman spectrum of catalyst C-7 contains a value of 2440 cm⁻¹. -1 The peak at that location, and 2668cm -1 The sharp peak at that location.

[0148] In catalyst C-7, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0149] The preparation conditions are listed in Table 1.

[0150] Example 8

[0151] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-8.

[0152] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of 2-methyltetrahydrofuran dropwise to A-8 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-8 and stir for 30 min; finally add 4.5 g of γ-methylpyridine and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-8.

[0153] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-8.

[0154] In the Raman spectrum of catalyst C-8, I was measured D1 / I G =0.47.

[0155] In the Raman spectrum of catalyst C-8, there is a 2434 cm⁻¹ -1 The peak at that location, and 2670cm -1 The sharp peak at that location.

[0156] In catalyst C-8, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0157] The preparation conditions are listed in Table 1.

[0158] Example 9

[0159] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-9.

[0160] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of γ-methylpyridine dropwise to A-9 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-9 and stir for 30 min; finally add 4.5 g of γ-methylpyridine and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-9.

[0161] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-9.

[0162] In the Raman spectrum of the catalyst C-9, I was measured D1 / I G =0.22.

[0163] In the Raman spectrum of catalyst C-9, there is a 2444 cm⁻¹... -1 The peak at that location, and 2670cm -1 The sharp peak at that location.

[0164] In catalyst C-9, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0165] The preparation conditions are listed in Table 1.

[0166] Example 10

[0167] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-10.

[0168] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of γ-methylpyridine dropwise to A-10 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-10 and stir for 30 min; finally add 4.5 g of cyclohexanone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-10.

[0169] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-10.

[0170] In the Raman spectrum of the catalyst C-10, I was measured. D1 / I G =0.78.

[0171] In the Raman spectrum of the catalyst C-10, there is a 2437 cm⁻¹. -1 The peak at that location, and 2660cm -1 The sharp peak at that location.

[0172] In catalyst C-10, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0173] The preparation conditions are listed in Table 1.

[0174] Example 11

[0175] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-11.

[0176] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of cyclohexanone dropwise to A-11 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-11 and stir for 30 min; finally add 4.5 g of γ-methylpyridine and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-11.

[0177] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-11.

[0178] In the Raman spectrum of the catalyst C-11, I was measured D1 / I G =0.83.

[0179] In the Raman spectrum of the catalyst C-11, there is a 2437 cm⁻¹. -1 The peak at that location, and 2666cm -1 The sharp peak at that location.

[0180] In catalyst C-11, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0181] The preparation conditions are listed in Table 1.

[0182] Example 12

[0183] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-12.

[0184] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of γ-methylpyridine dropwise to A-12 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-12 and stir for 30 min; finally add 4.5 g of N-methylpyrrolidone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-12.

[0185] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-12.

[0186] In the Raman spectrum of the catalyst C-12, I was measured. D1 / I G =0.21.

[0187] In the Raman spectrum of the catalyst C-12, there is a 2437 cm⁻¹. -1 The peak at that location, and 2666cm -1 The sharp peak at that location.

[0188] In catalyst C-12, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0189] The preparation conditions are listed in Table 1.

[0190] Example 13

[0191] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-13.

[0192] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of γ-methylpyridine dropwise to A-13 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-13 and stir for 30 min; finally add 4.5 g of 2-methyltetrahydrofuran, and continue stirring for 1 h to form a sludge-like substance. Dry it in an oven at 120 °C for 6 h, and label it B-13.

[0193] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-13.

[0194] In the Raman spectrum of the catalyst C-13, I was measured. D1 / I G =0.66.

[0195] The Raman spectrum of catalyst C-13 contains a value of 2440 cm⁻¹. -1 The peak at that location, and 2666cm -1 The sharp peak at that location.

[0196] In catalyst C-13, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0197] The preparation conditions are listed in Table 1.

[0198] Example 14

[0199] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-14.

[0200] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of γ-methylpyridine dropwise to A-14 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-14 and stir for 30 min; finally add 4.5 g of tetrahydrofuran and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-14.

[0201] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-14.

[0202] In the Raman spectrum of the catalyst C-14, I was measured D1 / I G =0.66.

[0203] The Raman spectrum of catalyst C-14 contains a value of 2437 cm⁻¹. -1 The peak at that location, and 2667cm -1 The sharp peak at that location.

[0204] In catalyst C-14, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0205] The preparation conditions are listed in Table 1.

[0206] Example 15

[0207] (a) Weigh 50 g of carbon nanotubes and mix them with 500 g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5 g of urea, purge with air to maintain a pressure of 1.2 MPa, and react at 120 °C for 6 h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100 °C for 6 h. Record this solid as A-15.

[0208] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 9.5 g of γ-methylpyridine dropwise into A-15 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise into A-15 and stir for 30 min to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-15.

[0209] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-15.

[0210] In the Raman spectrum of the catalyst C-15, I was measured. D1 / I G =0.91.

[0211] The Raman spectrum of catalyst C-15 contains a value of 2437 cm⁻¹. -1 The peak at that location, and 2667cm -1 The sharp peak at that location.

[0212] In catalyst C-15, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0213] The preparation conditions are listed in Table 1.

[0214] Example 16

[0215] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-16.

[0216] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of N-methyl-2-pyrrolidone dropwise to A-16 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-16 and stir for 30 min; finally add 4.5 g of N-methyl-2-pyrrolidone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-16.

[0217] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-16.

[0218] In the Raman spectrum of the catalyst C-16, I was measured. D1 / I G =0.23.

[0219] The Raman spectrum of catalyst C-16 contains a value of 2437 cm⁻¹. -1 The peak at that location, and 2666cm -1 The sharp peak at that location.

[0220] In catalyst C-16, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0221] The preparation conditions are listed in Table 1.

[0222] Example 17

[0223] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-17.

[0224] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 9.5 g of N-methyl-2-pyrrolidone dropwise into A-17 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise into A-17 and stir for 1 h 30 min to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-17.

[0225] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-17.

[0226] In the Raman spectrum of the catalyst C-17, I was measured. D1 / I G =0.24.

[0227] The Raman spectrum of catalyst C-17 contains a value of 2435 cm⁻¹. -1 The peak at that location, and 2655cm -1 The sharp peak at that location.

[0228] In catalyst C-17, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0229] The preparation conditions are listed in Table 1.

[0230] Example 18

[0231] (a) Weigh 50g of carbon nanotubes and mix them with 500g of propylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-18.

[0232] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of N-methyl-2-pyrrolidone dropwise to A-18 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-18 and stir for 30 min; finally add 4.5 g of N-methyl-2-pyrrolidone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-18.

[0233] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-18.

[0234] In the Raman spectrum of the catalyst C-18, I was measured D1 / I G =0.13.

[0235] The Raman spectrum of catalyst C-18 contains a value of 2438 cm⁻¹. -1 The peak at that location, and 2667cm -1 The sharp peak at that location.

[0236] In catalyst C-18, the oxygen content of the COOH surface functional groups accounts for 21.6% of the total oxygen content in the catalyst.

[0237] The preparation conditions are listed in Table 1.

[0238] Example 19

[0239] (a) Weigh 50g of carbon nanotubes and mix them with 500g of glycerol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-19.

[0240] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of N-methyl-2-pyrrolidone dropwise to A-19 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-19 and stir for 30 min; finally add 4.5 g of N-methyl-2-pyrrolidone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-19.

[0241] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-19.

[0242] In the Raman spectrum of the catalyst C-19, I was measured. D1 / I G =0.18.

[0243] The Raman spectrum of catalyst C-19 contains a value of 2437 cm⁻¹. -1 The peak at that location, and 2668cm -1 The sharp peak at that location.

[0244] In catalyst C-19, the oxygen content of the COOH surface functional groups accounts for 28.5% of the total oxygen content in the catalyst.

[0245] The preparation conditions are listed in Table 1.

[0246] Example 20

[0247] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture and react at 120℃ for 6h.

[0248] (b) Add 4.5 g of urea to the mixture from step (a), pressurize to 1.2 MPa by purging with air, and react at 120°C for 6 h. Dry in an oven at 100°C for 6 h, and record as A-20;

[0249] (c) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of N-methyl-2-pyrrolidone dropwise to A-20 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-20 and stir for 30 min; finally add 4.5 g of N-methyl-2-pyrrolidone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-20.

[0250] (d) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-20.

[0251] In the Raman spectrum of the catalyst C-20, I was measured. D1 / I G =0.13.

[0252] In the Raman spectrum of the catalyst C-20, there is a 2430 cm⁻¹ -1 The peak at that location, and 2660cm -1 The sharp peak at that location.

[0253] In catalyst C-20, the oxygen content of the COOH surface functional groups accounts for 22.8% of the total oxygen content in the catalyst.

[0254] The preparation conditions are listed in Table 1.

[0255] Example 21

[0256] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-21.

[0257] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of cyclohexanone dropwise to A-21 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-21 and stir for 30 min; finally add 4.5 g of cyclohexanone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-21.

[0258] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-21.

[0259] In the Raman spectrum of the catalyst C-21, I was measured. D1 / I G =0.22.

[0260] In the Raman spectrum of catalyst C-21, there is a 2434 cm⁻¹ -1 The peak at that location, and 2667cm -1 The sharp peak at that location.

[0261] In catalyst C-21, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0262] The preparation conditions are listed in Table 1.

[0263] Example 22

[0264] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-22.

[0265] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of 1-butyl-2-pyrrolidone dropwise to A-22 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-22 and stir for 30 min; finally add 4.5 g of 1-butyl-2-pyrrolidone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it B-22.

[0266] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-22.

[0267] In the Raman spectrum of the catalyst C-22, I was measured. D1 / I G=0.25.

[0268] In the Raman spectrum of the catalyst C-22, there is a 2434 cm⁻¹. -1 The peak at that location, and 2668cm -1 The sharp peak at that location.

[0269] In catalyst C-22, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0270] The preparation conditions are listed in Table 1.

[0271] Example 23

[0272] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-23.

[0273] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of 2-pyrrolidone dropwise to A-23 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-23 and stir for 30 min; finally add 4.5 g of 2-pyrrolidone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-23.

[0274] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-23.

[0275] In the Raman spectrum of the catalyst C-23, I was measured. D1 / I G =0.21.

[0276] The Raman spectrum of catalyst C-23 contains a value of 2440 cm⁻¹. -1 The peak at that location, and 2667cm -1 The sharp peak at that location.

[0277] In catalyst C-23, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0278] The preparation conditions are listed in Table 1.

[0279] Example 24

[0280] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-24.

[0281] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of N-methyl-2-pyrrolidone dropwise to A-24 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-24 and stir for 30 min; finally add 4.5 g of cyclohexanone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-24.

[0282] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-24.

[0283] In the Raman spectrum of the catalyst C-24, I was measured. D1 / I G =0.34.

[0284] The Raman spectrum of catalyst C-24 contains a value of 2435 cm⁻¹. -1 The peak at that location, and 2665cm -1 The sharp peak at that location.

[0285] In catalyst C-24, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0286] The preparation conditions are listed in Table 1.

[0287] Example 25

[0288] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-25.

[0289] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of cyclohexanone dropwise to A-25 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-25 and stir for 30 min; finally add 4.5 g of N-methyl-2-pyrrolidone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-25.

[0290] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-25.

[0291] In the Raman spectrum of the catalyst C-25, I was measured. D1 / I G =0.34.

[0292] The Raman spectrum of catalyst C-25 contains a value of 2434 cm⁻¹. -1 The peak at that location, and 2667cm -1 The sharp peak at that location.

[0293] In catalyst C-25, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0294] The preparation conditions are listed in Table 1.

[0295] Example 26

[0296] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-26.

[0297] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of N-methyl-2-pyrrolidone dropwise to A-26 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-26 and stir for 30 min; finally add 4.5 g of 2-pyrrolidone and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-26.

[0298] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-26.

[0299] In the Raman spectrum of the catalyst C-26, I was measured. D1 / I G =0.22.

[0300] The Raman spectrum of catalyst C-26 contains a value of 2438 cm⁻¹. -1 The peak at that location, and 2667cm -1 The sharp peak at that location.

[0301] In catalyst C-26, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0302] The preparation conditions are listed in Table 1.

[0303] Example 27

[0304] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-27.

[0305] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of N-methyl-2-pyrrolidone dropwise to A-27 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-27 and stir for 30 min; finally add 4.5 g of 2-methyltetrahydrofuran, and continue stirring for 1 h to form a sludge-like substance. Dry it in an oven at 120 °C for 6 h, and label it as B-27.

[0306] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-27.

[0307] In the Raman spectrum of the catalyst C-27, I was measured. D1 / I G =0.21.

[0308] The Raman spectrum of catalyst C-27 contains a value of 2440 cm⁻¹. -1 The peak at that location, and 2668cm -1 The sharp peak at that location.

[0309] In catalyst C-27, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0310] The preparation conditions are listed in Table 1.

[0311] Example 28

[0312] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-28.

[0313] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of N-methyl-2-pyrrolidone dropwise into A-28 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise into A-28 and stir for 30 min; finally add 4.5 g of tetrahydrofuran, and continue stirring for 1 h to form a sludge-like substance. Dry it in an oven at 120 °C for 6 h, and label it as B-28.

[0314] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-28.

[0315] In the Raman spectrum of the catalyst C-28, I was measured. D1 / I G =0.25.

[0316] The Raman spectrum of catalyst C-28 contains a value of 2440 cm⁻¹. -1 The peak at that location, and 2664cm -1 The sharp peak at that location.

[0317] In catalyst C-28, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0318] The preparation conditions are listed in Table 1.

[0319] Example 29

[0320] (a) Weigh 50g of carbon nanotubes and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-29.

[0321] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of N-methyl-2-pyrrolidone dropwise to A-29 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-29 and stir for 30 min; finally add 4.5 g of γ-methylpyridine and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-29.

[0322] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-29.

[0323] In the Raman spectrum of the catalyst C-29, I was measured. D1 / I G=0.54.

[0324] The Raman spectrum of catalyst C-29 contains a value of 2436 cm⁻¹. -1 The peak at that location, and 2667cm -1 The sharp peak at that location.

[0325] In catalyst C-29, the oxygen content of the COOH surface functional groups accounts for 30.9% of the total oxygen content in the catalyst.

[0326] The preparation conditions are listed in Table 1.

[0327] Example 30

[0328] (a) Weigh 50g of coconut shell charcoal (4-8 mesh), mix it with 500g of ethylene glycol, stir and sonicate to mix, then add 4.5g of urea, purge with air to maintain pressure to 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h, and record it as A-30;

[0329] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of γ-methylpyridine dropwise into A-30 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise into A-30 and stir for 30 min; finally add 4.5 g of NMP, continue stirring for 1 h, and dry in an oven at 120 °C for 6 h, which is recorded as B-30.

[0330] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-30.

[0331] In the Raman spectrum of the catalyst C-30, I was measured D1 / I G =0.31.

[0332] In the Raman spectrum of the catalyst C-30, there is a 2437 cm⁻¹. -1 The peak at that location, and 2666cm -1 The sharp peak at that location.

[0333] In catalyst C-30, the oxygen content of the COOH surface functional groups accounts for 34.5% of the total oxygen content in the catalyst.

[0334] The preparation conditions are listed in Table 1.

[0335] Example 31

[0336] (a) Weigh 50g of carbon nanofibers and mix them with 500g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5g of urea, purge with air to maintain a pressure of 1.2MPa, and react at 120℃ for 6h. Filter, wash with ethanol 5 times, collect the solid, and dry the solid in an oven at 100℃ for 6h. Record this solid as A-31.

[0337] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of γ-methylpyridine dropwise into A-30 and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise into A-30 and stir for 30 min; finally add 4.5 g of NMP and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and label it as B-31.

[0338] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-31.

[0339] In the Raman spectrum of the catalyst C-31, I was measured D1 / I G =0.25.

[0340] In the Raman spectrum of catalyst C-31, there is a 2437 cm⁻¹. -1 The peak at that location, and 2666cm -1 The sharp peak at that location.

[0341] In catalyst C-31, the oxygen content of the COOH surface functional groups accounts for 31.5% of the total oxygen content in the catalyst.

[0342] The preparation conditions are listed in Table 1.

[0343] Comparative Example 1

[0344] (a) Weigh 50g of carbon nanotubes and dry them in an oven at 100℃ for 6h. Record this as A-1'.

[0345] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 1.5 mL of chloropalladium acid dropwise to A-1' and stir for 30 min to form a sludge-like substance, and dry it in an oven at 120 °C for 6 h, and record it as B-1'.

[0346] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-1'.

[0347] In the Raman spectrum of the catalyst C-1', I was measured D1 / I G=0.04 (see Figure 1).

[0348] In the Raman spectrum of the catalyst C-1', a wavelength of 2670 cm⁻¹ was measured. -1 The vibration peak is low, while the intensity is low at 2400-2500 cm⁻¹. -1 There are no peaks within the range (see Figure 1).

[0349] The catalyst C1' underwent a weight loss experiment at 800°C, and the weight loss was approximately 2% by mass (see Figure 2).

[0350] The catalyst C-1' mainly contains Pd nanocrystals of 2 nm in size. This conventional nanoparticle configuration leads to the loss of active components and makes the nanoparticles more prone to agglomeration and sintering at high temperatures (see Figure 4).

[0351] In catalyst C-1', the oxygen content of the COOH surface functional group accounts for 10.1% of the total oxygen content in the catalyst.

[0352] The preparation conditions are listed in Table 1.

[0353] Comparative Example 2

[0354] (a) Weigh 50 g of carbon nanotubes and mix them with 500 g of ethylene glycol. Stir and sonicate to form an ink-like mixture. Then add 4.5 g of urea, purge with air to maintain a pressure of 1.2 MPa, and react at 120 °C for 6 h. Dry in an oven at 100 °C for 6 h, and record as A-2'.

[0355] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 1.5 mL of chloropalladium acid dropwise to A-2' and stir for 30 min to form a sludge-like substance, and dry it in an oven at 120 °C for 6 h, and record it as B-2'.

[0356] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-2'.

[0357] In the Raman spectrum of the catalyst C-2', I was measured D1 / I G =1.24.

[0358] In the Raman spectrum of the catalyst C-2', there is a 2667 cm⁻¹. -1 The peak is located at 2400-2500cm. -1 There are no peaks within the range.

[0359] In catalyst C-2', the oxygen content of the COOH surface functional group accounts for 30.9% of the total oxygen content in the catalyst.

[0360] The preparation conditions are listed in Table 1.

[0361] Comparative Example 3

[0362] (a) Weigh 50 grams of carbon nanotubes and dry them in an oven at 100°C for 6 hours. Record this as A-3'.

[0363] (b) Prepare an aqueous solution of chloropalladium acid with a Pd mass concentration of 0.002 g / mL and adjust the pH to 1 with hydrochloric acid; add 5 g of γ-methylpyridine dropwise to A-3' and stir continuously for 10 min, then add 1.5 mL of chloropalladium acid dropwise to A-3' and stir for 30 min; finally add 4.5 g of γ-methylpyridine and continue stirring for 1 h to form a sludge-like substance. Dry the sludge in an oven at 120 °C for 6 h and record it as B-3'.

[0364] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h to obtain catalyst C-3'.

[0365] In the Raman spectrum of the catalyst C-3', I was measured D1 / I G =0.09.

[0366] In the Raman spectrum of the catalyst C-3', there is a 2667 cm⁻¹. -1 The peak is located at 2400-2500cm. -1 There are no peaks within the range.

[0367] The oxygen content in the COOH surface functional group of catalyst C-3' accounts for 10.1% of the total oxygen content in the catalyst.

[0368] The preparation conditions are listed in Table 1.

[0369] In the above examples and comparative examples, Pd accounts for 0.5% of the total mass of the catalyst.

[0370] In Example 1, I D1 / I G =0.21, then I in Comparative Example 1 D1 / I G The value of 0.04 indicates that the graphitization of the carbon material was significantly reduced during the loading process, introducing more defects or heteroatom functional groups, which provided adsorption sites and protective covering for the metal.

[0371] Catalyst evaluation:

[0372] The catalysts of the above embodiments and comparative examples were evaluated using a batch stirred tank reactor under the following conditions:

[0373] Catalyst loading weight: 50 mg;

[0374] The reaction raw materials consist of 200 mg 4-CBA and 70 g PTA;

[0375] Reaction pressure: 1.2 MPa;

[0376] Reaction temperature: 120℃;

[0377] Reaction time: 30 min;

[0378] Catalyst evaluation methods:

[0379] The activity evaluation of the catalysts in the above embodiments and comparative examples was carried out in a 100 mL batch reactor. The reactants were added to the reactor, and the catalyst was loaded into a rotating frame inside the reactor. The reaction conditions were as described above, with a hydrogen partial pressure of 0.5 MPa. After the reaction, samples were taken to determine the 4-CBA content. The 4-CBA content was determined using an HP1100 HPLC instrument according to GB / T30921.1 standard. The experimental results are listed in Table 1.

[0380] Table 1

[0381] As shown in Table 1, the palladium-on-carbon catalyst prepared by this invention can improve the catalytic activity of the catalyst, thereby significantly reducing the residual amount of 4-CBA in the process of hydrorefining terephthalic acid.

[0382] Furthermore, the catalyst obtained in Example 7, after being used in the above evaluation method and separated by filtration, was reused. After 10 cycles of reaction, the residual amount of 4-CBA was 43 ppm, while that in Comparative Example 1 under the same conditions was 1934 ppm. Similarly, the residual amount after cycling in Example 9 was 71 ppm, in Comparative Example 2 it was 509 ppm, and in Comparative Example 3 it was 237 ppm. Clearly, the catalyst of the present invention has a longer lifespan.

[0383] The catalyst in Comparative Example 1 exists in the form of conventional nanoparticles, which leads to the loss of active components and makes it more prone to agglomeration and sintering of nanoparticles at high temperatures.

[0384] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A supported catalyst comprising a modified carbon material support having oxygen-containing functional groups, palladium, and a capping agent, wherein...

2. The supported catalyst according to claim 1, wherein... Preferably The covering agent may be present on the carrier surface; and / or The Raman spectrum of the catalyst contains a wavelength of 2400-2500 cm⁻¹. -1 The peak at 2600-2700cm -1 The peak at the point; and / or The catalyst begins to lose weight rapidly after 200°C under a nitrogen atmosphere, and the weight loss at 800°C is 4-10% by mass based on the total mass of the catalyst; and / or The catalyst is in the form of a coexistence of atomic-level distribution and nanoclusters. The clusters are amorphous particles. For example, the catalyst contains Pd clusters with a size of ≤2.2 nm, while also having Pd with a single atomic point distribution.

3. The supported catalyst according to claim 1 or 2, wherein... The covering agent is selected from compounds having the structures shown in Formula I, Formula II and Formula III: in, R1, R2, R3, R4, and R5 are each independently selected from hydrogen, deuterium, halogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 heteroalkyl, -NH2, -OH, substituted or unsubstituted amino, acyl, carbonyl, hydroxyl, or ester groups having 1-10 carbon atoms; the substituents are selected from deuterium, halogen, C1-C10 straight-chain or branched alkyl, C3-C10 cycloalkyl, C6-C20 aryl, -NH2, C1-C10 alkyl-substituted amino, or C3-C20 heteroaryl, and the number of substituents is selected from an integer between 1 and 10; n is 1 or 2; X is C or N; and / or The Pd content in the catalyst is 0.05-0.7% by mass, preferably 0.05-0.5% by mass, more preferably 0.1-0.5% by mass; and / or The covering agent has at least one of the following physical parameters: (1) a surface tension of 20-60 dyne / cm, preferably 25-35 dyne / cm; (2) a polarizability of the covering agent > 7 (10 -24 cm 3 ), preferably with a polarizability of 9.5-12 (10 -24 cm 3 ); and / or In the modified carbon material having oxygen-containing functional groups, the oxygen-containing functional groups are one or more of COOH, COH, COC, and C=O, preferably COOH and COH, and preferably the mass ratio of COOH to COH is ≥1:1; and / or In the presence of COOH, the mass ratio of oxygen in the COOH surface functional groups to the total mass of oxygen in the catalyst is 20-35%, preferably 23-34%; and / or The modified carbon material with oxygen-containing functional groups described above exhibits infrared spectra at 2900±50 cm⁻¹. - 1 Peaks; and / or The modified carbon material with oxygen-containing functional groups can be prepared by the following method, which includes mixing and reacting carbon material, polyol and pH adjuster.

4. The supported catalyst according to any one of claims 1-3, wherein... R1, R2, R3, R4, and R5 are each independently selected from hydrogen, deuterium, halogen, substituted or unsubstituted C1-C10 alkyl groups, -NH2, -OH, substituted or unsubstituted amino groups having 1-10 carbon atoms, and hydroxyl groups; the substituents are selected from deuterium, halogen, C1-C10 straight-chain or branched alkyl groups, -NH2, or C1-C10 alkyl-substituted amino groups, and the number of substituents is selected from an integer between 1 and 5. Preferably, R1, R2, R3, R4, and R5 are each independently selected from hydrogen, deuterium, F, Cl, Br, methyl, ethyl, propyl, butyl, or -NH2; more preferably, R1, R2, R3, R4, and R5 are each independently selected from hydrogen, deuterium, methyl, ethyl, propyl, or butyl; and / or The covering agent comprises one or more of γ-methylpyridine, 2-methyltetrahydrofuran, tetrahydrofuran, N-methylpyrrolidone, 1-butyl-2-pyrrolidone, and 2-pyrrolidone; and / or The carbon material is selected from one or more of carbon nanotubes, carbon nanofibers, and / or activated carbon, wherein the activated carbon is preferably coconut shell carbon; and / or The carbon nanotubes have an aspect ratio of 125-12500; and / or The carbon nanotubes have an outer diameter of 8-80 nm; and / or The polyol is selected from one or more of ethylene glycol, propylene glycol, and / or glycerol; and / or The pH adjuster is selected from urea and ammonia, preferably urea; and / or The mass ratio of the polyol to the carbon material is 5-20:1; and / or The mass ratio of the polyol to the pH adjuster is 200-50:1; and / or The reaction temperature is 100-150℃; and / or The reaction pressure is 0.5-1.5 MPa; and / or The reaction is carried out in a hydrothermal reactor; and / or The reaction time is 1-8 hours; and / or The reaction was carried out in an air atmosphere.

5. The method for preparing the supported catalyst according to any one of claims 1-4, wherein the preparation method comprises the following steps: (1) A modified carbon material carrier with oxygen-containing functional groups is treated with a first covering agent to obtain material A; (2) Material A is treated with an aqueous solution of palladium precursor to obtain material B; or The preparation method includes the following steps: (1') treating the modified carbon material with oxygen-containing functional groups with a first covering agent to obtain material A'; (2') treating material A' with an aqueous solution of palladium precursor to obtain material B'; (3') treating material B' with a second covering agent to obtain material C'; Then, material B or C' is reduced to obtain a supported catalyst. The first covering agent and / or the second covering agent are selected as described in any one of claims 1-4.

6. The preparation method according to claim 5, wherein, The first covering agent and / or the second covering agent are selected from compounds having the structures shown in Formula I, Formula II and Formula III as described in claim 3 or 4; and / or The first covering agent and the second covering agent are the same; and / or The first covering agent uses a more hydrophobic covering agent, while the second covering agent uses a more hydrophilic covering agent; and / or The palladium precursor aqueous solution is selected from one or more of chloropalladium acid aqueous solution, tetraaminopalladium nitrate aqueous solution, and / or palladium acetate aqueous solution; and / or The pH of the aqueous solution of the palladium precursor is 0.1-5; and / or The reducing agent used in the reduction treatment is one or more of sodium formate solution, formic acid, and hydrazine hydrate; and / or The amount of the reducing agent is 1-10% of the mass of the carrier; and / or The reduction treatment is performed at a temperature of 50-120°C; and / or The reduction process takes 0.5-3 hours.

7. The application of the supported catalyst according to any one of claims 1-4 or the supported catalyst prepared by the preparation method according to claim 5 or 6 in hydrogenation reactions, particularly in the hydrogenation purification of terephthalic acid.

8. A method for hydrogenating and purifying terephthalic acid, comprising: The reaction is carried out using crude terephthalic acid containing 4-CBA and hydrogen as raw materials in the presence of a supported catalyst according to any one of claims 1-4 or a supported catalyst prepared according to the preparation method of claim 5 or 6.

9. The method according to claim 8, wherein The pressure of the hydrogen gas is 0.1-1 MPa; and / or The reaction temperature is 100-150℃; and / or The reaction time is 20-40 min, preferably 25-35 min.

10. A composition for preparing a supported catalyst according to any one of claims 1-4, comprising a modified carbon material support having oxygen-containing functional groups, a covering agent, and an aqueous solution of a palladium precursor, wherein the modified carbon material support having oxygen-containing functional groups and the covering agent are as described in any one of claims 1-4, and the aqueous solution of the palladium precursor is prepared according to the method described in claim 5 or 6.

11. A method for preparing the composition according to claim 10, the preparation method comprising the following steps: (1) A modified carbon material carrier with oxygen-containing functional groups is treated with a first covering agent to obtain material A; (2) Material A is treated with an aqueous solution of palladium precursor to obtain material B, i.e., the composition. or The preparation method includes the following steps: (1') treating a modified carbon material with oxygen-containing functional groups with a first covering agent to obtain material A'; (2') treating material A' with an aqueous solution of palladium precursor to obtain material B'; (3') treating material B' with a second covering agent to obtain material C', i.e., the composition. The first covering agent and / or the second covering agent are selected as described in any one of claims 1-4.

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