Supported catalyst as well as preparation method and application thereof

Abstract

The invention provides a supported catalyst as well as a preparation method and application thereof. The supported catalyst comprises a carrier and palladium supported on the carrier, wherein the carrier comprises a modified carbon material with an oxygen-containing functional group. According to the method, the carrier is modified, the palladium precursor aqueous solution is treated with the protective agent, and the two components have a synergistic effect, so that the catalytic efficiency of the palladium-carbon catalyst can be remarkably improved, and the residual quantity of 4-CBA can be effectively reduced in a terephthalic acid hydrofining reaction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a supported catalyst and a preparation method and application thereof. BACKGROUND

[0002] Purified terephthalic acid is an important chemical raw material, but the crude terephthalic acid (CTA) obtained in the oxidation process contains by-products such as 4-carboxybenzaldehyde (4-CBA). 4-CBA has a great impact on the melting point of polyester and endangers product quality.

[0003] The supported catalyst is the most widely used catalyst for the hydrogenation purification of crude terephthalic acid. However, the commonly used supported catalysts generally use activated carbon as the carrier. For example, patent CN1189442C discloses a purification method for crude terephthalic acid, and the catalyst used takes granular or shaped activated carbon as the carrier. The patent controls the pore structure of the activated carbon, so that the active component Pd is mainly distributed on the surface layer of the carrier. Patent CN103028398B discloses a preparation method for a palladium-carbon catalyst for the hydrogenation purification of crude terephthalic acid. In the preparation of the catalyst, the precursor is subjected to heat treatment, so that the palladium entering the inner layer of the activated carbon carrier migrates to the surface of the carrier under the driving of heated water vapor. The loading amount of the catalyst in the surface layer with a depth of 0-20 μm of the catalyst prepared by the method is as high as 94.4% of the total loading amount. However, the traditional activated carbon carrier has a weak interaction with the active component palladium, which leads to poor dispersion of the active component Pd on the surface of the carrier and low hydrogenation efficiency. Therefore, the development of high-efficiency catalysts is a research hotspot at present. SUMMARY

[0004] The present application aims to overcome the shortcomings in the prior art and provides a supported catalyst and a preparation method and application thereof.

[0005] In a first aspect, the present application provides a supported catalyst comprising a carrier and palladium supported on the carrier, wherein the carrier comprises a modified carbon material having oxygen-containing functional groups.

[0006] In some embodiments, the total mass of oxygen elements in the supported catalyst is 1-10% of the mass of the carrier, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any value therebetween.

[0007] In some embodiments, the oxygen elements in the oxygen-containing functional groups account for 20-35% (for example, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34% or any value therebetween) of the total mass of oxygen elements in the catalyst.

[0008] In some embodiments, the oxygen-containing functional group comprises a carboxyl functional group and / or a hydroxyl functional group.

[0009] In some embodiments, the oxygen-containing functional group comprises a carboxyl functional group.

[0010] In some embodiments, the carbon material is one or more of carbon nanotubes, carbon nanofibers, or activated carbon.

[0011] In some embodiments, the carbon material is carbon nanotubes. Carbon nanotubes are easy to modify on the surface, easy to functionalize, and the electron transport is conducive to the subsequent catalytic reaction.

[0012] 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 therebetween.

[0013] 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 therebetween.

[0014] In some embodiments, the palladium accounts for 0.1-5% (for example, 0.12%, 0.24%, 0.37%, 0.43%, 0.48%, 0.51%, 0.56%, 0.62%, 0.73%, 1%, 2%, 3%, 4%, 5%, or any value therebetween) of the total mass of the supported catalyst.

[0015] In a second aspect, the present application provides a method for preparing a supported catalyst, comprising the following steps:

[0016] (1) treating a modified carbon material having an oxygen-containing functional group with a first protective agent to obtain material A;

[0017] (2) treating the material A with a palladium precursor aqueous solution to obtain material B;

[0018] (3) reducing the material B; or

[0019] The method for preparing a supported catalyst comprises the following steps:

[0020] (1) treating a modified carbon material having an oxygen-containing functional group with a first protective agent to obtain material A;

[0021] (2) treating the material A with a palladium precursor aqueous solution to obtain material B;

[0022] (3) treating material B with a second protective agent to obtain material C;

[0023] (4) treating material C with a reducing agent.

[0024] The first protective agent and / or the second protective agent comprises a 5-6 membered cyclic heteroatom-containing compound; the second protective agent comprises a compound having at least one of the following physical parameter conditions: (1) surface tension of 20-60 dyne / cm (e.g., 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 therebetween); (2) polarizability > 7 (10 -24 cm 3 ).

[0025] In some embodiments, the first protective agent and / or the second protective agent comprises a 5-6 membered cyclic heteroatom-containing compound; the second protective agent has at least one of the following physical parameter conditions: (1) surface tension of 25-35 dyne / cm; (2) polarizability of 9.5-12 (10 -24 cm 3 ), e.g., 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 therebetween.

[0026] In the mixing process of the first protective agent and the carrier (modified carbon material with oxygen-containing functional groups), the first protective agent is adsorbed in the pores of the carrier, so that no direct reduction reaction occurs between the carrier and the first protective agent when the carrier is impregnated with the aqueous solution of the palladium precursor, and the aggregation and growth of Pd single crystals can be avoided; and when the carrier is impregnated with the aqueous solution of the palladium precursor, Pd will preferentially position on the oxygen-containing functional groups (such as ethanol carboxylic acid group) of the carrier, thereby achieving high dispersion. The material C is further treated with the second protective agent, and the second protective agent covers the Pd sites to avoid the occurrence of the Oswald ripening effect during the drying process.

[0027] In some embodiments, the first protective agent has at least one of the following physical parameter conditions: (1) the surface tension is 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 therebetween; (2) the polarizability is > 7 (10 - 24 cm 3 ).

[0028] In some embodiments, the first protective agent has at least one of the following physical parameter conditions: (1) the surface tension is 25-35 dyne / cm; (2) the polarizability is 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 therebetween.

[0029] In some embodiments, the first protective agent and / or the second protective agent comprises a 5-6 membered cyclic N- and / or O-containing atom compound.

[0030] In some embodiments, the first protective agent and / or the second protective agent comprises a 5-6 membered cyclic N-atom containing compound.

[0031] In some embodiments, the first protective agent and / or the second protective agent comprises a 5-6 membered cyclic O-atom containing compound.

[0032] In some embodiments, the first protective agent and / or the second protective agent comprises a compound of the structure of Formula I:

[0033]

[0034] wherein R1, R2, R3, R4are each independently selected from the group consisting of hydrogen, deuterium, halogen, substituted or unsubstituted C1-C10alkyl, substituted or unsubstituted C1-C10alkoxy, substituted or unsubstituted C1-C10heteroalkyl, -NH2, -OH, substituted or unsubstituted amino having 1-10 carbon atoms, acyl, carbonyl, hydroxyl, ester; the substituted substituents are selected from the group consisting of deuterium, halogen, C1-C10linear or branched alkyl, C3-C10cycloalkyl, C6-C20aryl, -NH2, C1-C10alkyl substituted amino, or C3-C20heteroaryl, the number of the substituents is an integer selected from 1-10; n is 1 or 2.

[0035] In some embodiments, n is 1.

[0036] In some embodiments, R1, R2, R3, R4are each independently selected from the group consisting of hydrogen, deuterium, halogen, substituted or unsubstituted C1-C10alkyl, -NH2, -OH, substituted or unsubstituted amino having 1-10 carbon atoms, hydroxyl; the substituted substituents are selected from the group consisting of deuterium, halogen, C1-C10linear or branched alkyl, -NH2, C1-C10alkyl substituted amino, the number of the substituents is an integer selected from 1-5.

[0037] In some embodiments, R1, R2, R3, R4are each independently selected from the group consisting of hydrogen, deuterium, F, Cl, Br, methyl, ethyl, propyl, butyl, or -NH2.

[0038] In some embodiments, R1, R2, R3, R4are each independently selected from the group consisting of hydrogen, deuterium, methyl, ethyl, propyl, or butyl.

[0039] In some embodiments, the first protective agent and / or the second protective agent comprises one or more of N-methylpyrrolidone, 1-butyl-2-pyrrolidone, or 2-pyrrolidone.

[0040] In some embodiments, the first protective agent and / or the second protective agent comprises N-methylpyrrolidone.

[0041] In some embodiments, the first protective agent and the second protective agent are the same.

[0042] In some embodiments, the method of preparing the modified carbon material with oxygen-containing functional groups comprises mixing and reacting a carbon material, a polyol, and a pH adjusting agent.

[0043] The oxidation reaction between the carbon material and the polyol functionalizes the surface of the support with oxygen-containing functional groups (such as glycolic acid carboxyl groups), providing high dispersion sites for subsequent Pd loading.

[0044] In some embodiments, the carbon material is selected from one or more of carbon nanotubes, carbon nanofibers, or activated carbon.

[0045] In some embodiments, the carbon material is carbon nanotubes.

[0046] In some embodiments, the carbon nanotubes have an aspect ratio of 125-12500, such as 150, 550, 1070, 2500, 4200, 6100, 8000, 9500, 10500, 12000, or any value therebetween.

[0047] In some embodiments, the carbon nanotubes have an outer diameter of 8-80 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, or any value therebetween.

[0048] In some embodiments, the polyol is selected from one or more of ethylene glycol, propylene glycol, or glycerol.

[0049] In some embodiments, the pH adjusting agent is urea. The pH adjusting agent gradually generates ammonia water during the high-temperature reaction process to adjust the pH value during the oxidation of the carbon material, causing the reaction to occur.

[0050] In some embodiments, the mass ratio of the polyol to the carbon material is 5-20, such as 5:1, 7:1, 9:1, 11:1, 13:1, 15:1, 17:1, 19:1. Within this range, a rich functional oxygen-containing functional group can be formed on the surface of the carbon material.

[0051] In some embodiments, the mass ratio of the polyol to the pH adjusting agent is 200-50, such as 200:1, 180:1, 160:1, 140:1, 120:1, 100:1, 80:1, 60:1.

[0052] In some embodiments, the temperature of the reaction is 100-150℃, for example 100℃, 110℃, 120℃, 130℃, 140℃, 150℃.

[0053] In some embodiments, the pressure of the reaction is 0.5-1.5MPa, for example 0.5MPa, 0.7MPa, 0.9MPa, 1.1MPa, 1.3MPa, 1.5MPa.

[0054] In some embodiments, the reaction is carried out in an autoclave.

[0055] In some embodiments, the time of the reaction is 1-8h, for example 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h.

[0056] In some embodiments, the reaction is carried out under air atmosphere.

[0057] In some embodiments, the aqueous solution of palladium precursor is selected from one or more of aqueous chloropalladic acid, aqueous palladium tetraammine nitrate or aqueous palladium acetate.

[0058] In some embodiments, the ratio of the mass of water in the aqueous solution of palladium precursor to the total mass of the first protective agent and the second protective agent is 1-4; for example 1:1, 2:1, 3:1, 4:1.

[0059] In some embodiments, the pH of the aqueous solution of palladium precursor is 0.1-5, for example 0.1, 1, 2, 3, 4, 5.

[0060] In some embodiments, the pH of the aqueous solution of palladium precursor is adjusted using hydrochloric acid and / or nitric acid.

[0061] In some embodiments, the reducing agent used in the reduction treatment is one or more of sodium formate solution, formic acid or hydrazine hydrate.

[0062] In some embodiments, the amount of the reducing agent used is 1-10% of the mass of the carrier, for example 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%.

[0063] In some embodiments, the temperature of the reduction treatment is 50-120℃, for example 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃.

[0064] In some embodiments, the time of the reduction treatment is 0.5-3h, for example 1h, 1.5h, 2h, 2.5h.

[0065] In a third aspect, the present application provides a use of the supported catalyst of the first aspect of the present application or the supported catalyst prepared by the method of the second aspect of the present application in a hydrogenation reaction.

[0066] In a fourth aspect, the present application provides a method for hydrofining terephthalic acid, comprising: reacting crude terephthalic acid containing 4-CBA and hydrogen in the presence of the supported catalyst of the first aspect of the present application or the supported catalyst prepared by the method of the second aspect of the present application.

[0067] In some embodiments, the pressure of the hydrogen is 0.1-1 MPa; for example, 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.7 MPa, or 0.9 MPa.

[0068] In some embodiments, the temperature of the reaction is 100-150℃; for example, 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃. Since the catalyst of the present application has the characteristics of high dispersion and corresponding coordination effect, the use of the catalyst of the present application can effectively reduce the reaction temperature.

[0069] In some embodiments, the time of the reaction is 20-40 min; for example, 20 min, 25 min, 30 min, 35 min, or 40 min.

[0070] The present application uses polyols to treat carbon materials, which can introduce oxygen-containing functional groups on the surface of the carbon materials. The carbon materials undergo oxidation reaction in polyols and air in an autoclave, and the surface functionalization of the support is rich in carboxyl functional groups (such as glycolic acid carboxyl groups). Meanwhile, in the process of mixing the first protective agent and the support during the impregnation process, the first protective agent will be adsorbed in the pores of the support, so that the reduction reaction between the palladium precursor aqueous solution and the support will not occur directly, and the aggregation and growth of Pd single crystals can be avoided. When the palladium precursor aqueous solution is impregnated into the support, Pd will preferentially locate on the oxygen-containing functional groups (such as glycolic acid carboxyl functional groups), thereby achieving high dispersion. Finally, the second protective agent is added to cover the Pd sites again, thereby avoiding the occurrence of the Oswald ripening effect during the drying process. The present application can significantly improve the catalytic efficiency of the palladium-carbon catalyst by modifying the support and treating the palladium precursor aqueous solution with the protective agent, and the two can work together to effectively reduce the residual amount of 4-CBA in the terephthalic acid hydrofining reaction. BRIEF DESCRIPTION OF DRAWINGS

[0071] Figure 1 (a) is the SEM image of the catalyst obtained in Example 1;

[0072] Figure 1 (b) is the SEM image of the catalyst obtained in Comparative Example 1;

[0073] Figure 2 XPS spectra of the catalysts obtained in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0074] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be given below in combination with the embodiments and drawings. The specific embodiments described herein are only used to explain the present application and do not constitute any limitation to the present application.

[0075] The reagents used in the present application can be purchased from the market or prepared by the methods described in the present application, unless otherwise specified. The carbon nanotubes in the examples and comparative examples of the present application are purchased from the Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, with an aspect ratio of 125-12500 and an outer diameter of 8-80 nm.

[0076] The test method of the present application is as follows:

[0077] The content of Pd is tested by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the instrument model is Agilent 725-ES ICP-AES. A small amount of the above catalyst of the present application is weighed and dissolved in aqua regia and hydrofluoric acid, the acid solution is evaporated and diluted, and multiple measurements are taken and the average value is obtained, i.e. the average content (mass percent) of Pd.

[0078] The total mass of oxygen element and the proportion of COOH surface functional group in each embodiment and comparative example of the present application are tested and analyzed by X-ray photoelectron spectroscopy (XPS), and the instrument model is Kratos AXIS SUPRA equipped with Al target radiation Kα ray (1486.6 eV, excitation voltage 15 kV). The test result is corrected by taking the peak of C1s at 284.8 eV as the reference binding energy of the measured element. The metal Pd orbit is 3d, and the scanning interval is 0.1 eV.

[0079] Example 1

[0080] (a) 50 g of carbon nanotubes were weighed and mixed with 500 g of ethylene glycol, stirred and ultrasonically formed into an ink-like mixed solution, then 4.5 g of urea was added, air was introduced to maintain a pressure of 1.2 MPa, and reacted at 120℃ for 6 h. After filtration, the solid was collected after washing with ethanol for 5 times, and the above solid was dried in a 100℃ oven for 6 h, and was marked as A;

[0081] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and adjusted to a pH of 1 with hydrochloric acid. 5 g of N-methyl-2-pyrrolidone was added dropwise to A while stirring for 10 min, and then 1.5 mL of chloropalladic acid was added dropwise to A and stirred for 30 min. Finally, 4.5 g of N-methyl-2-pyrrolidone was added, and stirring was continued for 1 h at this point to form a sludge, which was dried in an oven at 120 °C for 6 h, and was labeled as B.

[0082] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h.

[0083] The preparation conditions are listed in Table 1. The SEM images of the catalyst prepared in this example are shown in Figure 1 (a), and it can be seen that the metal exists in the form of atomic-level bright spots.

[0084] Example 2

[0085] (a) 50 g of carbon nanotubes were mixed with 500 g of ethylene glycol, and an ink-like mixed solution was formed by stirring and ultrasonicating, and then 4.5 g of urea was added, air was introduced to maintain a pressure of 1.2 MPa, and reaction was performed at 120 °C for 6 h. After filtration and washing with ethanol for 5 times, the solid was collected, and the above-mentioned solid was dried in an oven at 100 °C for 6 h, and was labeled as A;

[0086] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and adjusted to a pH of 1 with hydrochloric acid. 9.5 g of N-methyl-2-pyrrolidone was added dropwise to A while stirring for 10 min, and then 1.5 mL of chloropalladic acid was added dropwise to A and stirred for 1 h 30 min to form a sludge, which was dried in an oven at 120 °C for 6 h, and was labeled as B.

[0087] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h.

[0088] The preparation conditions are listed in Table 1.

[0089] Example 3

[0090] (a) 50 g of carbon nanotubes were mixed with 500 g of ethylene glycol, and an ink-like mixed solution was formed by stirring and ultrasonicating, and then 4.5 g of urea was added, air was introduced to maintain a pressure of 1.2 MPa, and reaction was performed at 120 °C for 6 h. After filtration and washing with ethanol for 5 times, the solid was collected, and the above-mentioned solid was dried in an oven at 100 °C for 6 h, and was labeled as A;

[0091] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and adjusted to a pH of 1 with hydrochloric acid. 1.5 mL of chloropalladic acid was added to A while stirring for 30 min. Then 9.5 g of N-methyl-2-pyrrolidone was added, at which point stirring was continued for 1 h, forming a sludge that was dried in an oven at 120 °C for 6 h, labeled B.

[0092] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h.

[0093] Preparation conditions are listed in Table 1.

[0094] Example 4

[0095] (a) 50 g of carbon nanotubes were mixed with 500 g of propylene glycol and stirred ultrasonically to form an ink-like mixture, after which 4.5 g of urea was added, air was introduced to a pressure of 1.2 MPa, and the mixture was reacted at 120 °C for 6 h. After filtration, the solid was washed 5 times with ethanol, and the solid was collected and dried in an oven at 100 °C for 6 h, labeled A;

[0096] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and adjusted to a pH of 1 with hydrochloric acid. 5 g of N-methyl-2-pyrrolidone was added to A while stirring for 10 min, after which 1.5 mL of chloropalladic acid was added to A while stirring for 30 min. Finally, 4.5 g of N-methyl-2-pyrrolidone was added, at which point stirring was continued for 1 h, forming a sludge that was dried in an oven at 120 °C for 6 h, labeled B.

[0097] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h.

[0098] Preparation conditions are listed in Table 1.

[0099] Example 5

[0100] (a) 50 g of carbon nanotubes were mixed with 500 g of propylene glycol and stirred ultrasonically to form an ink-like mixture, after which 4.5 g of urea was added, air was introduced to a pressure of 1.2 MPa, and the mixture was reacted at 120 °C for 6 h. After filtration, the solid was washed 5 times with ethanol, and the solid was collected and dried in an oven at 100 °C for 6 h, labeled A;

[0101] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and adjusted to a pH of 1 with hydrochloric acid. 5 g of N-methyl-2-pyrrolidone was added to A while stirring for 10 min, after which 1.5 mL of chloropalladic acid was added to A while stirring for 30 min. Finally, 4.5 g of N-methyl-2-pyrrolidone was added, at which point stirring was continued for 1 h, forming a sludge that was dried in an oven at 120 °C for 6 h, labeled B.

[0102] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) heated to 80 °C and reduced for 1.5 h.

[0103] Preparation conditions are listed in Table 1.

[0104] Example 6

[0105] (a) 50 g of carbon nanotubes were mixed with 500 g of citric acid and stirred and sonicated to form an ink-like mixture. 4.5 g of urea was added and air was bubbled into the mixture to a pressure of 1.2 MPa. The mixture was heated to 120 °C and reacted for 6 h. The mixture was filtered and washed with ethanol 5 times. The solid was collected and dried in an oven at 100 °C for 6 h and labeled as Support A;

[0106] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and the pH was adjusted to 1 with hydrochloric acid. 5 g of N-methyl-2-pyrrolidone was added dropwise to Support A while stirring for 10 min. Then 1.5 mL of chloropalladic acid was added to Support A and stirred for 30 min. Finally, 4.5 g of N-methyl-2-pyrrolidone was added and the mixture was stirred for 1 h to form a sludge. The sludge was dried in an oven at 120 °C for 6 h and labeled as B.

[0107] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) heated to 80 °C and reduced for 1.5 h.

[0108] Preparation conditions are listed in Table 1.

[0109] Example 7

[0110] (a) 50 g of carbon nanotubes were mixed with 500 g of ethylene glycol and stirred and sonicated to form an ink-like mixture. The mixture was heated to 120 °C and reacted for 6 h.

[0111] (b) 4.5 g of urea was added to the mixture of step (a) and air was bubbled into the mixture to a pressure of 1.2 MPa. The mixture was heated to 120 °C and reacted for 6 h. The mixture was dried in an oven at 100 °C for 6 h and labeled as A.

[0112] (c) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and the pH was adjusted to 1 with hydrochloric acid. 5 g of N-methyl-2-pyrrolidone was added dropwise to Support A while stirring for 10 min. Then 1.5 mL of chloropalladic acid was added to Support A and stirred for 30 min. Finally, 4.5 g of N-methyl-2-pyrrolidone was added and the mixture was stirred for 1 h to form a sludge. The sludge was dried in an oven at 120 °C for 6 h and labeled as B.

[0113] (d) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) heated to 80 °C and reduced for 1.5 h.

[0114] Preparation conditions are listed in Table 1.

[0115] Example 8

[0116] (a) 50 g of carbon nanotubes were weighed out, mixed with 500 g of ethylene glycol, and stirred and ultrasonically treated to form an ink-like mixture, then 4.5 g of urea was added, air was introduced to maintain a pressure of 1.2 MPa, and reaction was carried out at 120°C for 6 h. After filtration, the solid was collected after washing with ethanol 5 times, and the solid was dried in an oven at 100°C for 6 h, and was marked as A;

[0117] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL, and hydrochloric acid was used to adjust the pH to 1; 5 g of cyclohexanone was added dropwise into A while stirring for 10 min, then 1.5 mL of chloropalladic acid was added dropwise into A while stirring for 30 min; finally, 4.5 g of cyclohexanone was added, and stirring was continued for 1 h at this time to form a sludge, which was dried in an oven at 120°C for 6 h, and was marked as B.

[0118] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) and heated to 80°C, and reduction was carried out for 1.5 h.

[0119] Preparation conditions are listed in Table 1.

[0120] Example 9

[0121] (a) 50 g of carbon nanotubes were weighed out, mixed with 500 g of ethylene glycol, and stirred and ultrasonically treated to form an ink-like mixture, then 4.5 g of urea was added, air was introduced to maintain a pressure of 1.2 MPa, and reaction was carried out at 120°C for 6 h. After filtration, the solid was collected after washing with ethanol 5 times, and the solid was dried in an oven at 100°C for 6 h, and was marked as A;

[0122] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL, and hydrochloric acid was used to adjust the pH to 1; 5 g of 1-butyl-2-pyrrolidone was added dropwise into A while stirring for 10 min, then 1.5 mL of chloropalladic acid was added dropwise into A while stirring for 30 min; finally, 4.5 g of 1-butyl-2-pyrrolidone was added, and stirring was continued for 1 h at this time to form a sludge, which was dried in an oven at 120°C for 6 h, and was marked as B.

[0123] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) and heated to 80°C, and reduction was carried out for 1.5 h.

[0124] Preparation conditions are listed in Table 1.

[0125] Example 10

[0126] (a) 50 g of carbon nanotubes were weighed out, mixed with 500 g of ethylene glycol, stirred and ultrasonically treated to form an ink-like mixture, 4.5 g of urea was then added, air was introduced and pressure was maintained at 1.2 MPa, and reaction was carried out at 120°C for 6 h. After filtration, the solid was collected after being washed with ethanol for 5 times, and the solid was dried in an oven at 100°C for 6 h, and was marked as A;

[0127] (b) An aqueous solution of chloropalladic acid was prepared, with a Pd mass concentration of 0.002 g / mL, and hydrochloric acid was used to adjust the pH to 1; 5 g of 2-pyrrolidone was added dropwise into A while stirring for 10 min, and then 1.5 mL of chloropalladic acid was added dropwise into A and stirred for 30 min; finally, 4.5 g of 2-pyrrolidone was added, and stirring was continued for 1 h at this time to form a sludge, which was dried in an oven at 120°C for 6 h, and was marked as B.

[0128] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80°C, and reduction was carried out for 1.5 h.

[0129] The preparation conditions are listed in Table 1.

[0130] Example 11

[0131] (a) 50 g of carbon nanotubes were weighed out, mixed with 500 g of ethylene glycol, stirred and ultrasonically treated to form an ink-like mixture, 4.5 g of urea was then added, air was introduced and pressure was maintained at 1.2 MPa, and reaction was carried out at 120°C for 6 h. After filtration, the solid was collected after being washed with ethanol for 5 times, and the solid was dried in an oven at 100°C for 6 h, and was marked as A;

[0132] (b) An aqueous solution of chloropalladic acid was prepared, with a Pd mass concentration of 0.002 g / mL, and hydrochloric acid was used to adjust the pH to 1; 5 g of 2-pyrrolidone was added dropwise into A while stirring for 10 min, and then 1.5 mL of chloropalladic acid was added dropwise into A and stirred for 30 min; finally, 4.5 g of 2-pyrrolidone was added, and stirring was continued for 1 h at this time to form a sludge, which was dried in an oven at 120°C for 6 h, and was marked as B.

[0133] (c) The dried solid was placed in 500 mL of sodium formate solution (5 wt.%) and heated to 80°C, and reduction was carried out for 1.5 h.

[0134] The preparation conditions are listed in Table 1.

[0135] Example 12

[0136] (a) 50 g of carbon nanotubes were weighed out, mixed with 500 g of ethylene glycol, stirred and ultrasonically treated to form an ink-like mixture, 4.5 g of urea was then added, air was introduced and pressure was maintained at 1.2 MPa, and reaction was carried out at 120°C for 6 h. After filtration, the solid was collected after being washed with ethanol for 5 times, and the solid was dried in an oven at 100°C for 6 h, and was marked as A;

[0137] (b) Prepare an aqueous solution of chloropalladic 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 while stirring for 10 min, then add 1.5 mL of chloropalladic acid dropwise to A and stir for 30 min. Finally, add 4.5 g of N-methyl-2-pyrrolidone, and continue stirring for 1 h at this time to form a sludge. Dry the sludge in an oven at 120 °C for 6 h, and label the product as B.

[0138] (c) Place the dried solid in 500 mL of a sodium formate solution (5 wt.%) and heat to 80 °C for 1.5 h.

[0139] The preparation conditions are listed in Table 1.

[0140] Example 13

[0141] (a) Weigh 50 g of carbon nanotubes, mix with 500 g of ethylene glycol, and stir and ultrasonic to form an ink-like mixed solution. Then add 4.5 g of urea, and introduce 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, and label the product as A;

[0142] (b) Prepare an aqueous solution of chloropalladic 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 while stirring for 10 min, then add 1.5 mL of chloropalladic acid dropwise to A and stir for 30 min. Finally, add 4.5 g of 2-pyrrolidone, and continue stirring for 1 h at this time to form a sludge. Dry the sludge in an oven at 120 °C for 6 h, and label the product as B.

[0143] (c) Place the dried solid in 500 mL of a sodium formate solution (5 wt.%) and heat to 80 °C for 1.5 h.

[0144] The preparation conditions are listed in Table 1.

[0145] Example 14

[0146] (a) Weigh 50 g of carbon nanotubes, mix with 500 g of ethylene glycol, and stir and ultrasonic to form an ink-like mixed solution. Then add 4.5 g of urea, and introduce 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, and label the product as A;

[0147] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and adjusted to a pH of 1 with hydrochloric acid. 5 g of N-methyl-2-pyrrolidone was added dropwise to A while stirring for 10 min, then 1.5 mL of chloropalladic acid was added dropwise to A and stirred for 30 min. Finally, 4.5 g of 2-methyltetrahydrofuran was added, at which point stirring was continued for 1 h, forming a sludge, which was dried in an oven at 120 °C for 6 h, labeled B.

[0148] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) and heated to 80 °C for 1.5 h.

[0149] Preparation conditions are listed in Table 1.

[0150] Example 15

[0151] (a) 50 g of carbon nanotubes were mixed with 500 g of ethylene glycol and stirred and sonicated to form an ink-like mixture, then 4.5 g of urea was added, air was introduced to maintain a pressure of 1.2 MPa, and 120 °C was reacted for 6 h. After filtration, the solid was washed with ethanol 5 times, and the solid was collected. The above solid was dried in an oven at 100 °C for 6 h, labeled A;

[0152] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and adjusted to a pH of 1 with hydrochloric acid. 5 g of N-methyl-2-pyrrolidone was added dropwise to A while stirring for 10 min, then 1.5 mL of chloropalladic acid was added dropwise to A and stirred for 30 min. Finally, 4.5 g of 2-methyltetrahydrofuran was added, at which point stirring was continued for 1 h, forming a sludge, which was dried in an oven at 120 °C for 6 h, labeled B.

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

[0154] Preparation conditions are listed in Table 1.

[0155] Example 16

[0156] (a) 50 g of carbon nanotubes were mixed with 500 g of ethylene glycol and stirred and sonicated to form an ink-like mixture, then 4.5 g of urea was added, air was introduced to maintain a pressure of 1.2 MPa, and 120 °C was reacted for 6 h. After filtration, the solid was washed with ethanol 5 times, and the solid was collected. The above solid was dried in an oven at 100 °C for 6 h, labeled A;

[0157] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and adjusted to pH 1 with hydrochloric acid. 5 g of N-methyl-2-pyrrolidone was added dropwise to A while stirring for 10 min, and then 1.5 mL of chloropalladic acid was added dropwise to A and stirred for 30 min. Finally, 4.5 g of γ-picoline was added, and stirring was continued for 1 h at this time to form a sludge, which was dried in an oven at 120°C for 6 h, and was marked as B.

[0158] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) and heated to 80°C for 1.5 h.

[0159] The preparation conditions are listed in Table 1.

[0160] Comparative Example 1

[0161] (a) 50 g of carbon nanotubes was weighed and marked as A;

[0162] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and adjusted to pH 1 with hydrochloric acid. 11 mL of chloropalladic acid was added to A and stirred for 1.7 h to form a sludge, which was dried in an oven at 120°C for 6 h, and was marked as B.

[0163] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) and heated to 80°C for 1.5 h.

[0164] The preparation conditions are listed in Table 1. The SEM of the catalyst prepared in the present comparative example is shown in Fig. 2(b), and it can be seen that the catalyst prepared in the present comparative example has nanoparticles with a large size. According to the Scherrer equation, Figure 1 (b) The SEM of the catalyst prepared in the present comparative example is shown in Fig. 2(b), and it can be seen that the catalyst prepared in the present comparative example has nanoparticles with a large size. According to the Scherrer equation, Figure 1 It can be seen that the metal dispersion degrees of the catalysts prepared in Example 1 and Comparative Example 1 are different.

[0165] Comparative Example 2

[0166] (a) 50 g of carbon nanotubes was weighed and mixed with 500 g of ethylene glycol to form an ink-like mixture under stirring and ultrasonic, and then 4.5 g of urea was added, air was introduced to pressurize to 1.2 MPa, and reaction was carried out at 120°C for 6 h. Drying was carried out in a 100°C oven for 6 h, and was marked as A;

[0167] (b) An aqueous solution of chloropalladic acid was prepared with a Pd mass concentration of 0.002 g / mL and adjusted to pH 1 with hydrochloric acid. 11 mL of chloropalladic acid was added to A and stirred for 1.7 h to form a sludge, which was dried in an oven at 120°C for 6 h, and was marked as B.

[0168] (c) The dried solid was placed in 500 mL of a sodium formate solution (5 wt.%) and heated to 80°C for 1.5 h.

[0169] The preparation conditions are listed in Table 1.

[0170] Comparative Example 3

[0171] (a) Take 50 g of carbon nanotubes, marked as A;

[0172] (b) Prepare an aqueous solution of chloropalladic acid with a Pd mass concentration of 0.002 g / mL, and adjust the pH to 1 with hydrochloric acid; drop 5 g of N-methyl-2-pyrrolidone into A under constant stirring for 10 min, then drop 1.5 mL of chloropalladic acid into A and stir for 30 min; finally, add 4.5 g of N-methyl-2-pyrrolidone, and at this time, continue stirring for 1 h to form a sludge, dry in an oven at 120°C for 6 h, and mark as B.

[0173] (c) Place the dried solid in 500 mL of a sodium formate solution (5 wt.%) and heat to 80°C for 1.5 h for reduction.

[0174] The preparation conditions are listed in Table 1.

[0175] The Pd in the above examples and comparative examples accounts for 0.5% of the total mass of the catalyst.

[0176] Catalyst evaluation:

[0177] The catalysts in the above examples and comparative examples are evaluated in a batch stirred tank, and the specific conditions are as follows:

[0178] Catalyst loading mass: 50 mg;

[0179] Reaction raw material composition: 200 mg of 4-CBA;

[0180] Reaction pressure: 1.2 MPa;

[0181] Reaction temperature: 120°C;

[0182] Reaction time: 30 min;

[0183] Catalyst evaluation method:

[0184] The activity evaluation of the catalysts in the above examples and comparative examples is carried out in a 100 mL batch reactor. The reaction raw materials are put into the reactor, the catalyst is loaded into the rotating frame in the reactor, and the reaction conditions are as described above, with a hydrogen partial pressure of 0.5 MPa. After the reaction is completed, the sample is taken for detection of the 4-CBA content. The 4-CBA content is detected by using an HP1100 type HPLC instrument, and tested according to the GB / T30921.1 standard. The experimental results are listed in Table 1.

[0185] The XPS of Example 1 and Comparative Example 1 above is shown in Table 2. Figure 2 Figure 2 ​It can be seen that the proportion of oxygen in the COOH surface functional group in Example 1 can be calculated by the ratio of the integral area of the COOH peak to the total area of the oxygen peak. After calculation, the oxygen in the COOH surface functional group accounts for 30.9% of the total mass of oxygen in the catalyst, and the oxygen in the COOH surface functional group in Comparative Example 1 accounts for 10.1% of the total mass of oxygen in the catalyst. The total mass of oxygen in the catalyst in the above examples is 1-10% of the mass of the carrier. By adding the area of all oxygen peaks and dividing by the sensitivity factor, the proportion of oxygen in the carrier can be obtained.

[0186] Table 1

[0187]

[0188]

[0189]

[0190] The proportion of COOH surface functional group in Table 1 refers to the percentage of oxygen in the COOH surface functional group accounting for the total mass of oxygen in the catalyst.

[0191] As can be seen from Table 1, the palladium-carbon catalyst prepared by the present application can improve the catalytic activity of the catalyst, thereby significantly reducing the residual amount of 4-CBA in the process of hydrogenation of terephthalic acid.

[0192] In Example 5, glycerol is used to modify the carrier. Since the glycerol chain is longer, it is relatively difficult to oxidize. Since the oxidation of the three hydroxyl groups is located on the surface of the carbon carrier, it is difficult to control the adsorption position of Pd, resulting in a decrease in catalyst activity, and a higher residual amount of 4-CBA during the catalytic reaction.

[0193] In Example 6, citric acid is used as a competitive adsorbent, which is only adsorbed on the surface of the carrier and does not participate in the oxidation reaction. Therefore, although the proportion of COOH surface functional group is high, the catalytic activity is poor.

[0194] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A supported catalyst comprising a support and palladium supported on the support, the support comprising a modified carbon material having oxygen-containing functional groups, Preferably, the total mass of oxygen element in the supported catalyst is 1-10% of the mass of the support; Preferably, the oxygen element in the oxygen-containing functional groups is 20-35% of the total mass of oxygen element in the catalyst; Preferably, the oxygen-containing functional groups comprise carboxyl functional groups and / or hydroxyl functional groups; Preferably, the carbon material is one or more of carbon nanotubes, carbon nanofibers or activated carbon, preferably carbon nanotubes; Preferably, the aspect ratio of the carbon nanotubes is 125-12500, and / or the outer diameter of the carbon nanotubes is 8-80 nm; Preferably, the palladium accounts for 0.1-5% of the total mass of the supported catalyst.

2. A method for preparing a supported catalyst, comprising the following steps: (1) treating a modified carbon material having oxygen-containing functional groups with a first protective agent to obtain material A; (2) treating the material A with a palladium precursor aqueous solution to obtain material B; (3) reducing the material B; or treating the material B with a second protective agent to obtain material C; reducing the material C, the first protective agent and / or the second protective agent comprises a 5-6 membered cyclic heteroatom-containing compound; the second protective agent comprises a compound having at least one of the following physical parameter conditions: (1) the surface tension is 20-60 dyne / cm; (2) polarizability > 7 (10 -24 cm 3 ).

3. The preparation method according to claim 2, characterized in that, the first protective agent has at least one of the following physical parameter conditions: (1) the surface tension is 20-60 dyne / cm; (2) polarizability > 7 (10 -24 cm 3 ); Preferably, the first protective agent and / or the second protective agent comprises a 5-6 membered cyclic N- and / or O-containing compound, More preferably, the first protective agent and / or the second protective agent comprises a compound having the structure shown in Formula I: wherein R1, R2, R3, R4 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 having 1-10 carbon atoms, acyl, carbonyl, hydroxyl, ester; the substituted substituent is selected from deuterium, halogen, C1-C10 linear or branched alkyl, C3-C10 cycloalkyl, C6-C20 aryl, -NH2, C1-C10 alkyl-substituted amino or C3-C20 heteroaryl, the number of the substituents being selected from an integer between 1 and 10; n is 1 or 2, preferably 1.

4. The production method according to claim 3, characterized by, R1, R2, R3, R4 are each independently selected from hydrogen, deuterium, halogen, substituted or unsubstituted C1-C10 alkyl, -NH2, -OH, substituted or unsubstituted amino having 1-10 carbon atoms, hydroxyl; the substituted substituent is selected from deuterium, halogen, C1-C10 linear or branched alkyl, -NH2, C1-C10 alkyl-substituted amino, the number of the substituents being selected from an integer between 1 and 5; Preferably, R1, R2, R3, R4 are each independently selected from hydrogen, deuterium, F, Cl, Br, methyl, ethyl, propyl, butyl or -NH2; Preferably, R1, R2, R3, R4 are each independently selected from hydrogen, deuterium, methyl, ethyl, propyl or butyl; Preferably, the first protective agent and / or the second protective agent comprises one or more of N-methylpyrrolidone, 1-butyl-2-pyrrolidone or 2-pyrrolidone; preferably, the first protective agent and / or the second protective agent comprises N-methylpyrrolidone. Preferably, the first protective agent and the second protective agent are the same.

5. The production method according to any one of claims 2 to 4, characterized by, The method for preparing the modified carbon material with oxygen-containing functional groups comprises: mixing and reacting a carbon material, a polyol and a pH adjusting agent; Preferably, the carbon material is selected from one or more of carbon nanotubes, carbon nanofibers or activated carbon; preferably, the carbon material is carbon nanotubes; preferably, 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 Preferably, the polyol is selected from one or more of ethylene glycol, propylene glycol or glycerol; and / or Preferably, the pH adjusting agent is urea; and / or Preferably, the mass ratio of the polyol to the carbon material is 5-20; and / or Preferably, the mass ratio of the polyol to the pH adjusting agent is 200-50.

6. The production method according to claim 5, wherein Preferably, the reaction is carried out at a temperature of 100-150℃; and / or Preferably, the reaction is carried out at a pressure of 0.5-1.5 MPa; and / or Preferably, the reaction is carried out for 1-8 h; and / or Preferably, the reaction is carried out in an air atmosphere.

7. The production method according to any one of claims 2 to 6, characterized by, Preferably, the aqueous solution of the palladium precursor is selected from one or more of an aqueous solution of chloropalladic acid, an aqueous solution of tetraammine palladium nitrate or an aqueous solution of palladium acetate; Preferably, the aqueous solution of the palladium precursor has a pH of 0.1-5; Preferably, the pH of the aqueous solution of the palladium precursor is adjusted using hydrochloric acid and / or nitric acid.

8. The production method according to any one of claims 2 to 7, characterized by, Preferably, the reducing agent used in the reduction treatment is one or more of a sodium formate solution, formic acid or hydrazine hydrate.

9. Use of the supported catalyst of claim 1 or the supported catalyst prepared by the method of any one of claims 2-8 in a hydrogenation reaction.

10. A method for hydrofmishing terephthalic acid comprising: Preferably, the hydrogen gas has a pressure of 0.1-1 MPa; and / or Preferably, the reaction is carried out at a temperature of 100-150℃; and / or Preferably, the reaction is carried out for 20-40 min. ​

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