Preparation method of oxygen-containing functional group modified carbon-coated platinum catalyst, prepared catalyst and application thereof

Abstract

The invention discloses a preparation method of an oxygen-containing functional group modified carbon-coated platinum catalyst, the prepared catalyst and application thereof. The preparation method of the catalyst comprises the following steps: (1) weighing a supported platinum catalyst, adding water into the supported platinum catalyst, uniformly mixing, adding a soluble saccharide carbon source compound, stirring to react, heating in a water bath, evaporating to dryness, performing vacuum drying until moisture is dried, and performing high-temperature roasting in an inert protective atmosphere after moisture is removed, thereby obtaining the catalyst. The carbon-coated platinum catalyst is prepared; and (2) dispersing the carbon-coated platinum catalyst in water, adding an oxidant, carrying out stirring reaction, and then carrying out vacuum drying to obtain the oxygen-containing functional group modified carbon-coated platinum catalyst. The invention provides the application of the catalyst in preparation of p-aminophenol through nitrobenzene hydrogenation rearrangement, and high reaction rate and p-aminophenol selectivity can be obtained.

Description

Technical Field

[0001] The technical scheme of the present invention relates to the field of catalytic reactions, and specifically to a method for preparing a carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups, the prepared carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups, and its application in the catalytic hydrogenation rearrangement of nitrobenzene to prepare p-aminophenol. Background Art

[0002] Para-aminophenol is an organic chemical intermediate widely used in various industries, including pharmaceuticals, dyes, pesticides and antioxidants. At present, para-aminophenol is mostly prepared by catalytic hydrogenation of nitrobenzene, and supported metal nanoparticles with high hydrogenation activity are selected as catalysts for preparing para-aminophenol by hydrogenation of nitrobenzene, such as Pt, Pd, Ni, Au, Ru, etc. Although these precious metal catalysts show high catalytic activity and are easy to separate, the nitrobenzene hydrogenation catalytic system is a very complex four-phase reaction, which includes nitrobenzene in the oil phase, deionized water in the water phase, hydrogen in the gas phase and concentrated sulfuric acid in the solid phase. However, the presence of concentrated sulfuric acid is a major challenge to supported metal catalysts, which may cause metal loss, oxidation and corrosion to a certain extent, which greatly increases the cost in industrial production, and precious metals bring a series of problems such as resource consumption, cost increase, and residual heavy metal pollution. Therefore, people have proposed an encapsulated catalyst that can prevent the active components from being corroded by strong acids.

[0003] Chinese patent CN 114308024 B discloses a method for preparing a doped carbon-wrapped platinum catalyst, which uses an acid-insoluble protective layer-a carbon layer to wrap the active metal, thereby achieving the effect of protecting the active metal under acidic reaction conditions, and first adding hydrogen peroxide, and then adding a soluble carbon source compound and a soluble heteroatom-containing compound to obtain the target product. The prepared doped carbon-wrapped platinum catalyst has good catalytic hydrogenation performance in an acidic solution. Since platinum is covered by a carbon layer of a specific structure and thickness, when it is in an acidic hydrogenation environment, the metal platinum will not be lost, so the catalyst has good stability in the hydrogenation reaction in a sulfuric acid environment. The reaction of nitrobenzene catalytic hydrogenation rearrangement to prepare p-aminophenol under the action of the doped carbon-wrapped platinum catalyst has better stability and target product selectivity than the platinum catalyst without carbon wrapping. Heteroatoms doped in the carbon layer can increase the defects of the carbon layer, which is conducive to the resistance of electrons penetrating the carbon layer, and can regulate the catalytic performance, which is particularly suitable for selective hydrogenation reactions. Chinese patent CN 114308027 A discloses a method for preparing a supported carbon-coated bimetallic catalyst. By using hydroxyethyl cellulose to allow the carbon source and the metal to contact and fuse better, the carbon layer on the carbon-coated catalyst obtained is more evenly coated on the metal. By treating it in an air atmosphere at an appropriate temperature, oxygen atoms can be introduced into and on the surface of the carbon layer to form acidic oxygen-containing functional groups, which helps to improve the catalytic activity and selectivity of the target product. The complete carbon layer has weak adsorption capacity for both hydrogen and nitrobenzene. Grafting electron-rich oxygen-containing functional groups on the outermost carbon layer can significantly enhance the adsorption and activation capacity for hydrogen. The acidic oxygen-containing functional groups can also help the reaction intermediate phenylhydroxylamine to further undergo Bamberger rearrangement reaction, thereby improving the reaction rate and selectivity of the target product.

[0004] Studies have shown that the electron transfer between metal and graphene layers does not exceed three to four carbon layers at most. Although reducing the number of graphene layers will promote the transfer of electrons to the graphene shell, thereby improving the catalytic activity, the reduction in the number of graphene layers means the weakening of the mechanical strength of the catalyst. Therefore, it is necessary to invent a catalyst with high catalytic stability and catalytic activity for the method of hydrogenating nitrobenzene to prepare p-aminophenol. Summary of the invention

[0005] The present invention aims to provide a method for preparing an oxygen-containing functional group modified encapsulated platinum catalyst, the prepared oxygen-containing functional group modified carbon encapsulated platinum catalyst and its application in the preparation of p-aminophenol by hydrogenation of nitrobenzene, which can obtain a higher reaction rate and p-aminophenol selectivity.

[0006] In order to solve the above-mentioned invention object, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a carbon-encapsulated platinum catalyst modified with an oxygen-containing functional group, the preparation method comprising:

[0008] (1) Weighing a supported platinum catalyst, wherein the supported platinum catalyst comprises a carrier and a metal active component supported on the carrier, wherein the metal active component is platinum, and the carrier of the supported platinum catalyst is TiO2, SiO2 or ZrO2, adding water to the supported platinum catalyst and mixing evenly, adding a soluble sugar carbon source compound, stirring at 20 to 60° C. for 0.5 to 10 h, placing in a water bath and heating to dryness, and then vacuum drying until the water is dried, after removing the water, calcining at 400 to 1000° C. for 2 to 20 h under an inert protective atmosphere to obtain a carbon-encapsulated platinum catalyst; the soluble sugar carbon source compound is at least one of glucose, sucrose, fructose, maltose and lactose; and the mass ratio of the soluble sugar carbon source compound to the supported platinum catalyst is 0.5 to 2:1;

[0009] (2) dispersing the carbon-encapsulated platinum catalyst obtained in step (1) in water, adding an oxidant, stirring at 20 to 100° C. for 1 to 24 hours, and then vacuum drying to obtain a carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups; the oxidant is at least one of H2O2, HNO3, potassium permanganate, and H2SO4, and the mass ratio of the oxidant to the carbon-encapsulated platinum catalyst is 0.1 to 1.6:10.

[0010] In the present invention, the supported platinum catalyst can be a commercial catalyst or can be prepared by itself according to existing literature. Preferably, the support of the supported platinum catalyst is ZrO2. Preferably, the loading amount of platinum in the supported platinum catalyst (relative to the support) is 1 to 5 wt%.

[0011] Preferably, the loading amount of platinum in the supported platinum catalyst is 1 to 5 wt%.

[0012] Preferably, in step (1), the mass ratio of the supported platinum catalyst to water is 1:5-10.

[0013] Preferably, in step (1), the soluble sugar carbon source compound is added in the form of an aqueous solution, and the concentration of the aqueous solution is 10 to 50 wt%.

[0014] Preferably, in step (1), the vacuum drying temperature is 80-110° C., and the vacuum drying time is 6-12 hours.

[0015] Preferably, the inert protective atmosphere is at least one of nitrogen, argon and helium.

[0016] Preferably, in step (1), the calcination temperature is 400-900° C. and the calcination time is 10-20 hours.

[0017] In the particularly preferred step (1) of the present invention, the carrier of the supported platinum catalyst is ZrO2, the soluble sugar carbon source compound is glucose, the mass ratio of the soluble sugar carbon source compound to the supported platinum catalyst is 0.75:1, the calcination temperature is 600°C, and the calcination time is 20h.

[0018] Preferably, in step (2), the mass ratio of the carbon-encapsulated platinum catalyst to water is 1:5-10.

[0019] Preferably, in step (2), the mass ratio of the oxidant to the carbon-encapsulated platinum catalyst is 0.2 to 0.5: 10. In the present invention, the oxidant is preferably added in the form of an aqueous solution.

[0020] Preferably, in step (2), the oxidant is H2O2.

[0021] Preferably, in step (2), after adding the oxidant, stirring is carried out at 20 to 90° C. for 1 to 10 hours.

[0022] Preferably, in step (2), the vacuum drying temperature is 80-110° C., and the drying time is 6-12 hours.

[0023] In the particularly preferred step (2) of the present invention, the oxidant is H2O2, which is added in the form of a 1-5wt% aqueous solution, and the mass ratio of the oxidant to the carbon-encapsulated platinum catalyst is 0.4:10. After adding the oxidant, stirring is carried out at 40°C for 1 hour.

[0024] In a second aspect, the present invention provides a carbon-coated platinum catalyst modified with oxygen-containing functional groups prepared according to the preparation method described in the first aspect.

[0025] In a third aspect, the present invention provides the use of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups described in the second aspect in the preparation of p-aminophenol by hydrogenation rearrangement of nitrobenzene.

[0026] Preferably, the specific method of the application is: adding distilled water, 98wt% concentrated sulfuric acid, a surfactant, nitrobenzene, and a carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups into an acid-resistant high-pressure reactor, introducing hydrogen gas and carrying out a hydrogenation rearrangement reaction under stirring conditions to obtain the target product p-aminophenol.

[0027] As a further preference, the surfactant is hexadecyltrimethylammonium chloride.

[0028] As a further preference, the mass ratio of distilled water, 98wt% concentrated sulfuric acid, surfactant, nitrobenzene, and carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups is 100-500:10-100:0.2-1:20-90:1.

[0029] As a further preference, the reaction temperature of the hydrogenation rearrangement reaction is 60-90° C., and the hydrogen pressure in the reactor is 0.6-2.0 MPa.

[0030] The present invention provides a preparation method of a carbon-wrapped platinum catalyst modified with an oxygen-containing functional group and its application in preparing p-aminophenol by hydrogenation rearrangement of nitrobenzene. The present invention introduces oxygen-containing groups by oxidizing the carbon-wrapped catalyst with an oxidant, thereby enhancing the ability of the metal to transfer electrons to the carbon layer and reducing the work function, which helps to reconstruct electrons on the surface of the carbon layer and enhance the ability to dissociate hydrogen, thereby increasing the reaction speed and enhancing the reaction catalytic activity.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The introduction of oxygen-containing functional groups can enhance the hydrophilicity of the catalyst and further improve the catalytic activity.

[0033] (2) The oxidation process is simple and convenient, and choosing hydrogen peroxide for oxidation is more gentle. While removing impurities in the carbon material, some oxygen-containing groups are introduced. In addition, the decomposition products of hydrogen peroxide are only water and carbon dioxide, and no complicated post-treatment process is required, which is environmentally friendly.

[0034] (3) The catalyst of the present invention contains only the metal platinum active component and no other metal elements, thereby reducing the difficulty of recycling the precious metal catalyst.

[0035] (4) The catalyst of the present invention can enhance the ability to dissociate hydrogen in the application of nitrobenzene hydrogenation rearrangement to prepare p-aminophenol, thereby increasing the reaction rate and enhancing the catalytic activity of the reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a TEM image of the carbon-wrapped platinum catalyst modified with oxygen-containing functional groups prepared in Example 1. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is described below with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0038] If no specific conditions are specified in the examples of the present invention, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be obtained by conventional technical means or purchased commercially.

[0039] The commercial catalysts used in the examples of the present invention were purchased from Deqing Degong Chemical Co., Ltd.

[0040] Embodiment 1

[0041] Weigh 10g of commercial 3wt% Pt / ZrO2, add it to 50ml of water and mix evenly, add 15g of 50wt% glucose aqueous solution, stir at 25°C for 2h, place it in a 50°C water bath to evaporate to dryness, and vacuum dry it at 110°C for 10h to remove moisture; then calcine it at 600°C under nitrogen for 20h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 20g of 2wt% hydrogen peroxide, stir at 40°C for 1h, and vacuum dry it at 110°C for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0042] Embodiment 2

[0043] Weigh 10g of commercial 1wt% Pt / CeO2, add it to 50ml of water and mix evenly, add 10g of 50wt% lactose aqueous solution, stir at 50℃ for 3h, place in a 70℃ water bath to evaporate, and vacuum dry at 110℃ for 10h to remove moisture; then calcine it at 500℃ under nitrogen for 15h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 15g of 4wt% hydrogen peroxide, stir at 50℃ for 2h, and vacuum dry at 110℃ for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0044] Embodiment 3

[0045] Weigh 10g of commercial 3wt% Pt / SiO2, add it to 50ml of water and mix evenly, add 30g of 50wt% sucrose aqueous solution, stir at 60℃ for 1h, place it in a 40℃ water bath to evaporate, and vacuum dry it at 110℃ for 10h to remove moisture; then calcine it at 800℃ under nitrogen for 10h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 10g of 4wt% potassium permanganate solution, stir at 30℃ for 3h, and vacuum dry it at 110℃ for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0046] Embodiment 4

[0047] Weigh 10g of commercial 2wt% Pt / TiO2, add it to 50ml of water and mix evenly, add 20g of 50wt% glucose aqueous solution, stir at 40℃ for 4h, place in a 60℃ water bath to evaporate, and vacuum dry at 110℃ for 10h to remove moisture; then calcine it at 400℃ under nitrogen for 12h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 5g of 8wt% hydrogen peroxide, stir at 60℃ for 5h, and vacuum dry at 110℃ for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0048] Embodiment 5

[0049] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it to 50ml of water and mix evenly, add 10g of 50wt% glucose aqueous solution, stir at 30℃ for 2h, place it in a 50℃ water bath to evaporate, and vacuum dry it at 110℃ for 10h to remove moisture; then calcine it at 900℃ under nitrogen for 12h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 10g of 2wt% nitric acid, stir at 80℃ for 6h, and vacuum dry it at 110℃ for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0050] Embodiment 6

[0051] Weigh 10g of commercial 1wt% Pt / / ZrO2, add it to 50ml of water and mix evenly, add 15g of 50wt% glucose aqueous solution, stir at 25°C for 3h, place in a 40°C water bath to evaporate, and vacuum dry at 110°C for 10h to remove moisture; then calcine it at 700°C under nitrogen for 25h to obtain a carbon-wrapped platinum catalyst; weigh 10g of the carbon-wrapped platinum catalyst, add it to 50ml of water, add 5g of 4wt% nitric acid, stir at 50°C for 4h, and vacuum dry at 110°C for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0052] Embodiment 7

[0053] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups prepared in Example 1 were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 80 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.7 wt%, and the p-aminophenol selectivity was 75.4 wt%.

[0054] Embodiment 8

[0055] In an acid-resistant high-pressure reactor, 200 g of distilled water, 30 g of 98 wt% concentrated sulfuric acid, 50 g of nitrobenzene, 0.6 g of hexadecyltrimethylammonium chloride, and 1 g of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups prepared in Example 2 were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 90° C. and the hydrogen pressure was 2 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 180 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.5 wt%, and the p-aminophenol selectivity was 70.8 wt%.

[0056] Embodiment 9

[0057] In an acid-resistant high-pressure reactor, 450 g of distilled water, 80 g of 98 wt% concentrated sulfuric acid, 70 g of nitrobenzene, 1 g of hexadecyltrimethylammonium chloride, and 1 g of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups prepared in Example 3 were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 100° C. and the hydrogen pressure was 1.5 MPa, and stirring was started at a stirring rate of 1000 r / min and a complete reaction time of 175 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.8 wt%, and the p-aminophenol selectivity was 71.6 wt%.

[0058] Embodiment 10

[0059] In an acid-resistant high-pressure reactor, 300 g of distilled water, 45 g of 98 wt% concentrated sulfuric acid, 30 g of nitrobenzene, 0.55 g of hexadecyltrimethylammonium chloride, and 1 g of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups prepared in Example 4 were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 80° C. and the hydrogen pressure was 1.3 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 163 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.0 wt%, and the p-aminophenol selectivity was 70.3 wt%.

[0060] Embodiment 11

[0061] In an acid-resistant autoclave, 500 g of distilled water, 90 g of 98 wt% concentrated sulfuric acid, 60 g of nitrobenzene, 0.8 g of hexadecyltrimethylammonium chloride, and 1 g of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups prepared in Example 5 were added, the autoclave was closed, and the air in the autoclave was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 95° C. and the hydrogen pressure was 1.2 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 136 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.9 wt%, and the p-aminophenol selectivity was 72.4 wt%.

[0062] Embodiment 12

[0063] In an acid-resistant high-pressure reactor, 250 g of distilled water, 25 g of 98 wt% concentrated sulfuric acid, 75 g of nitrobenzene, 0.9 g of hexadecyltrimethylammonium chloride, and 1 g of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups prepared in Example VI were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 90° C. and the hydrogen pressure was 1.8 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 154 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.2 wt%, and the p-aminophenol selectivity was 73.4 wt%.

[0064] Embodiment 13

[0065] In an acid-resistant autoclave, 400 g of distilled water, 75 g of 98 wt % concentrated sulfuric acid, 85 g of nitrobenzene, 0.65 g of hexadecyltrimethylammonium chloride, and 1 g of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups prepared in Example 1 were added, the autoclave was closed, and the air in the autoclave was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 70° C. and the hydrogen pressure was 1.5 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 90 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.2 wt %, and the p-aminophenol selectivity was 71.8 wt %.

[0066] Table 1 Application results of catalyst prepared in Example 1

[0067] Number of applications Catalyst addition amount / g Reaction time Nitrobenzene conversion rate / % Selectivity for aminophenol / % 1 1 80min 99.7 75.4 2 0 80min 99.4 75.1 3 0 78min 99.3 74.7 4 0.05 81min 99.5 75.1 5 0 79min 99.7 74.7 6 0 80min 99.3 74.5 7 0.05 83min 99.3 74.3 8 0 83min 99.3 74.4 9 0 81min 99.6 74.2 10 0.05 85min 99.4 74.0

[0068] Comparative Example 1

[0069] Comparative Example 1 investigated the performance of carbon-encapsulated platinum catalysts modified with oxygen-containing functional groups prepared by different oxidants. Compared with Example 1, nitric acid was used instead of hydrogen peroxide, which slowed down the reaction time and reduced the selectivity of aminophenol.

[0070] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it to 50ml water and mix evenly, add 15g of 50wt% glucose aqueous solution, stir at 25°C for 2h, place it in a 50°C water bath to evaporate to dryness, and vacuum dry it at 110°C for 10h to remove moisture; then calcine it at 600°C under nitrogen for 20h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml water, add 20g of 2wt% nitric acid, stir at 40°C for 1h, and vacuum dry it at 110°C for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0071] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the above-prepared carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 140 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.4 wt%, and the p-aminophenol selectivity was 64.3 wt%.

[0072] Comparative Example 2

[0073] Comparative Example 2 investigated the performance of carbon-encapsulated platinum catalysts modified with oxygen-containing functional groups prepared from different carbon sources. Compared with Example 1, lactose was used to replace glucose, which slowed down the reaction time and reduced the selectivity for aminophenol.

[0074] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it to 50ml water and mix evenly, add 15g of 50wt% lactose aqueous solution, stir at 25°C for 2h, place it in a 50°C water bath to evaporate to dryness, and vacuum dry it at 110°C for 10h to remove moisture; then calcine it at 600°C under nitrogen for 20h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml water, add 20g of 2wt% hydrogen peroxide, stir at 40°C for 1h, and vacuum dry it at 110°C for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0075] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the above-prepared carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min and a complete reaction time of 100 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.7 wt%, and the p-aminophenol selectivity was 63.1 wt%.

[0076] Comparative Example 3

[0077] Comparative Example 3 investigated the performance of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups obtained at a lower carbonization temperature. Compared with Example 1, the carbonization temperature was lowered, the reaction time was slowed down, and the selectivity of aminophenol was slightly reduced.

[0078] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it to 50ml of water and mix evenly, add 15g of 50wt% glucose aqueous solution, stir at 25°C for 2h, place it in a 50°C water bath to evaporate to dryness, and vacuum dry it at 110°C for 10h to remove moisture; then calcine it at 400°C under nitrogen for 20h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 20g of 2wt% hydrogen peroxide, stir at 40°C for 1h, and vacuum dry it at 110°C for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0079] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the above-prepared carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 122 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.3 wt%, and the p-aminophenol selectivity was 74.2 wt%.

[0080] Comparative Example 4

[0081] Comparative Example 4 investigated the performance of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups obtained at a higher carbonization temperature. Compared with Example 1, the carbonization temperature was increased, resulting in a slower reaction time.

[0082] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it to 50ml of water and mix evenly, add 15g of 50wt% glucose aqueous solution, stir at 25°C for 2h, place it in a 50°C water bath to evaporate to dryness, and vacuum dry it at 110°C for 10h to remove moisture; then calcine it at 900°C under nitrogen for 20h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 20g of 2wt% hydrogen peroxide, stir at 40°C for 1h, and vacuum dry it at 110°C for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0083] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the above-prepared carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 137 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.4 wt%, and the p-aminophenol selectivity was 74.5 wt%.

[0084] Comparative Example 5

[0085] Comparative Example 5 investigated the performance of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups obtained by oxidation with higher concentration of hydrogen peroxide. Compared with Example 1, increasing the oxidation concentration slowed down the reaction time and reduced the selectivity of aminophenol.

[0086] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it to 50ml of water and mix evenly, add 15g of 50wt% glucose aqueous solution, stir at 25°C for 2h, place it in a 50°C water bath to evaporate to dryness, and vacuum dry it at 110°C for 10h to remove moisture; then calcine it at 600°C under nitrogen for 20h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 80g of 2wt% hydrogen peroxide, stir at 40°C for 1h, and vacuum dry it at 110°C for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0087] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the above-prepared carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 104 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.7 wt%, and the p-aminophenol selectivity was 73.1 wt%.

[0088] Comparative Example 6

[0089] Comparative Example 6 investigated the performance of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups obtained by oxidation with lower concentration of hydrogen peroxide. Compared with Example 1, the oxidation concentration was reduced, the reaction time was slowed down, and the selectivity of aminophenol was reduced.

[0090] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it to 50ml of water and mix evenly, add 15g of 50wt% glucose aqueous solution, stir at 25°C for 2h, place it in a 50°C water bath to evaporate to dryness, and vacuum dry it at 110°C for 10h to remove moisture; then calcine it at 600°C under nitrogen for 20h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 5g of 2wt% hydrogen peroxide, stir at 40°C for 1h, and vacuum dry it at 110°C for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0091] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the above-prepared carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 95 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.5 wt%, and the p-aminophenol selectivity was 73.0 wt%.

[0092] Comparative Example 7

[0093] Comparative Example 7 investigated the performance of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups obtained at a higher oxidation temperature. Compared with Example 1, increasing the oxidation temperature slowed down the reaction time and reduced the selectivity of aminophenol.

[0094] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it to 50ml of water and mix evenly, add 15g of 50wt% glucose aqueous solution, stir at 25°C for 2h, place it in a 50°C water bath to evaporate to dryness, and vacuum dry it at 110°C for 10h to remove moisture; then calcine it at 600°C under nitrogen for 20h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 20g of 2wt% hydrogen peroxide, stir at 100°C for 1h, and vacuum dry it at 110°C for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0095] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the above-prepared carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 101 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.4 wt%, and the p-aminophenol selectivity was 73.8 wt%.

[0096] Comparative Example 8

[0097] Comparative Example 8 investigated the performance of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups obtained at a lower oxidation temperature. Compared with Example 1, the oxidation temperature was lowered, the reaction time was slowed down, and the selectivity of aminophenol was reduced.

[0098] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it to 50ml of water and mix evenly, add 15g of 50wt% glucose aqueous solution, stir at 25°C for 2h, place it in a 50°C water bath to evaporate to dryness, and vacuum dry it at 110°C for 10h to remove moisture; then calcine it at 600°C under nitrogen for 20h to obtain a carbon-wrapped platinum catalyst; weigh 10g of carbon-wrapped platinum catalyst, add it to 50ml of water, add 20g of 2wt% hydrogen peroxide, stir at 20°C for 1h, and vacuum dry it at 110°C for 10h to obtain a carbon-wrapped platinum catalyst modified with oxygen-containing functional groups.

[0099] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the above-prepared carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 92 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.9 wt%, and the p-aminophenol selectivity was 73.9 wt%.

[0100] Comparative Example 9

[0101] Comparative Example 9 investigated the performance of the carbon-encapsulated platinum catalyst prepared without oxidation treatment. Compared with Example 1, no oxidation treatment was performed, which slowed down the reaction time and reduced the selectivity of aminophenol.

[0102] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it into 50ml water and mix evenly, add 15g of 50wt% glucose aqueous solution, stir at 25℃ for 2h, place in a 50℃ water bath to evaporate, and vacuum dry at 110℃ for 10h to remove moisture; then calcine it at 600℃ under nitrogen for 20h to obtain a carbon-encapsulated platinum catalyst.

[0103] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the carbon-encapsulated platinum catalyst prepared above were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min, and the complete reaction time was 230 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, the nitrobenzene conversion rate was 99.2 wt%, and the p-aminophenol selectivity was 57.9 wt%.

[0104] Comparative Example 10

[0105] Comparative Example 10 investigated the performance of the supported platinum catalyst without carbon coating.

[0106] Add 150g of distilled water, 15g of 98wt% concentrated sulfuric acid, 25g of nitrobenzene, 0.5g of hexadecyltrimethylammonium chloride, and 1g of commercial 3% Pt / ZrO2 catalyst to an acid-resistant high-pressure reactor, close the reactor, replace the air in the reactor with nitrogen three times, and then replace it with hydrogen three times; raise the temperature to 75°C, the hydrogen pressure to 1MPa, start stirring, the stirring rate is 1000r / min, and the complete reaction time is 60min; stop the reaction, wait until the temperature drops to room temperature, take out the reaction liquid, filter and recover the catalyst, and analyze the filtrate by liquid chromatography. The recovered catalyst continues to be used in the experiment, and the reaction conditions are the same as above.

[0107] Table 2 Application results of commercial Pt / / ZrO2 catalysts

[0108] Number of applications Catalyst addition amount / g Reaction time Nitrobenzene conversion rate / % Selectivity for aminophenol / % 1 1 60min 99.4 45.7 2 0 65min 99.8 44.4 3 0 68min 99.1 41.3 4 0.05 78min 99.33 39.8 5 0 120min 99.0 33.5

[0109] Comparative Example 11

[0110] Comparative Example 11 investigated the performance of catalysts prepared by different oxidation sequences. Compared with Example 1, the first oxidation treatment method slowed down the reaction time and reduced the selectivity of aminophenol.

[0111] Weigh 10g of commercial 3wt% Pt / / ZrO2, add it to 50ml water and 20g of 2wt% hydrogen peroxide, stir at 40℃ for 1h, then add 15g of 50wt% glucose aqueous solution, stir at 25℃ for 2h, evaporate in a 50℃ water bath, and vacuum dry at 110℃ for 10h to remove moisture; then calcine it at 600℃ under nitrogen for 20h to obtain a carbon-encapsulated platinum catalyst.

[0112] In an acid-resistant high-pressure reactor, 150 g of distilled water, 15 g of 98 wt% concentrated sulfuric acid, 25 g of nitrobenzene, 0.5 g of hexadecyltrimethylammonium chloride, and 1 g of the carbon-encapsulated platinum catalyst prepared above were added, the reactor was closed, and the air in the reactor was replaced with nitrogen three times, and then replaced with hydrogen three times; the temperature was raised to 75° C. and the hydrogen pressure was 1 MPa, and stirring was started at a stirring rate of 1000 r / min and a complete reaction time of 200 min; the reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was filtered and recovered, and the filtrate was analyzed by liquid chromatography, and the nitrobenzene conversion rate was 99.3 wt%, and the p-aminophenol selectivity was 62.9 wt%.

Claims

1. A method for preparing a carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups, characterized in that: The preparation method comprises: (1) Weighing a supported platinum catalyst, wherein the supported platinum catalyst comprises a carrier and a metal active component supported on the carrier, wherein the metal active component is platinum, and the carrier of the supported platinum catalyst is TiO2, SiO2 or ZrO2, adding water to the supported platinum catalyst and mixing evenly, adding a soluble sugar carbon source compound, stirring at 20 to 60° C. for 0.5 to 10 h, placing in a water bath and heating to dryness, and then vacuum drying until the water is dried, after removing the water, calcining at 400 to 1000° C. for 2 to 20 h under an inert protective atmosphere to obtain a carbon-encapsulated platinum catalyst; the soluble sugar carbon source compound is at least one of glucose, sucrose, fructose, maltose and lactose; and the mass ratio of the soluble sugar carbon source compound to the supported platinum catalyst is 0.5 to 2:1; (2) dispersing the carbon-encapsulated platinum catalyst obtained in step (1) in water, adding an oxidant, stirring at 20 to 100° C. for 1 to 24 hours, and then vacuum drying to obtain a carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups; the oxidant is at least one of H2O2, HNO3, potassium permanganate, and H2SO4, and the mass ratio of the oxidant to the carbon-encapsulated platinum catalyst is 0.1 to 1.6:

10.

2. The preparation method according to claim 1, characterized in that: The loading amount of platinum in the supported platinum catalyst is 1-5wt%.

3. The preparation method according to claim 1, characterized in that: In step (1), the soluble sugar carbon source compound is added in the form of an aqueous solution, and the concentration of the aqueous solution is 10 to 50 wt%.

4. The preparation method according to claim 1, characterized in that: In step (1), the calcination temperature is 400-900° C. and the calcination time is 10-20 hours.

5. The preparation method according to claim 1, characterized in that: In step (1), the carrier of the supported platinum catalyst is ZrO2, the soluble sugar carbon source compound is glucose, the mass ratio of the soluble sugar carbon source compound to the supported platinum catalyst is 0.75:1, the calcination temperature is 600°C, and the calcination time is 20h.

6. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of the oxidant to the carbon-encapsulated platinum catalyst is 0.2 to 0.5:

10.

7. The preparation method according to claim 1, characterized in that: In step (2), after adding the oxidant, stirring is carried out at 20 to 90° C. for 1 to 10 hours.

8. The preparation method according to claim 1, characterized in that: In step (2), the oxidant is H2O2, which is added in the form of a 1-5wt% aqueous solution. The mass ratio of the oxidant to the carbon-encapsulated platinum catalyst is 0.4:

10. After adding the oxidant, stirring is performed at 40°C for 1 hour.

9. A carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups obtained according to the preparation method of any one of claims 1 to 8.

10. Use of the carbon-encapsulated platinum catalyst modified with oxygen-containing functional groups as claimed in claim 9 in the preparation of p-aminophenol by hydrogenation rearrangement of nitrobenzene.

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