A P-doped carbon-encapsulated noble metal catalyst, its preparation method and application

Abstract

This invention discloses a phosphorus-doped carbon-encapsulated noble metal catalyst, its preparation method, and its application. The preparation method involves complexing a noble metal with a phosphorus-containing organic ligand. After washing and filtration, the metal-organic coordination complex crystal and activated carbon are sequentially dispersed in a carbohydrate compound solution. Hydrothermal treatment combines the metal-organic coordination complex crystal, carbohydrate compound, and activated carbon. After carbonization, the metal is completely encapsulated within the carbon layer, thus preparing the phosphorus-doped carbon-encapsulated noble metal catalyst. This phosphorus-doped carbon-encapsulated noble metal catalyst is used in the hydrogenation rearrangement of nitrobenzene to produce p-aminophenol. The catalyst has advantages such as simple process flow, high stability, reusability, high nitrobenzene conversion rate, and high selectivity for p-aminophenol.

Description

Technical Field

[0001] This patent relates to a P-doped carbon-encapsulated noble metal catalyst, its preparation method, and its application in the hydrogenation rearrangement of nitrobenzene to prepare p-aminophenol. Technical Background

[0002] p-Aminophenol (PAP) is a widely used fine chemical intermediate applicable in pharmaceuticals, pesticides, fuels, rubber additives, and photosensitive materials. Among various p-aminophenol production processes, the catalytic hydrogenation of nitrobenzene to p-aminophenol is highly competitive in industry due to its advantages such as low cost, simple process, easy product separation, and environmental friendliness. This method uses nitrobenzene as a raw material and proceeds in two steps. The first step involves the catalytic hydrogenation of nitrobenzene to generate a phenylhydroxylamine intermediate. The second step involves the phenylhydroxylamine undergoing a Bamberger rearrangement in an acidic medium via phase transfer to generate p-aminophenol. Therefore, the catalyst not only needs good catalytic performance but also good acid resistance.

[0003] Chinese patent CN101440040A proposes using a solid acid as a support to prepare a Pt-solid acid composite catalyst for the hydrogenation of nitrobenzene to p-aminophenol in aqueous solution. This method exhibits low equipment corrosion and mild reaction conditions, but the catalyst preparation is complex, requires a large amount of catalyst, and results in a low PAP yield of only 17%-83%. Chinese patent CN103553954A uses pressurized CO2 / H2O to form an acid that promotes the hydrogenation of nitrobenzene to form PHA, which then rearranges into PAP to generate p-aminophenol. This method requires high CO2 pressure, a long reaction time, and low PAP selectivity. To address issues such as metal leaching and catalyst deactivation, a coated catalyst is prepared for this reaction system. The coated catalyst encapsulates the metal active sites of the catalyst within a carbon layer, effectively improving catalyst stability. Furthermore, the interaction between the shell and the metal promotes PAP formation. The coated catalyst separates the metal active sites from hydrogen ions in the reaction environment, effectively extending the lifespan of the metal catalyst. Chinese patent CN115722254A prepared an in-situ encapsulated Pt@H-ASM-5 catalyst, encapsulating the active metal within zeolite nanocrystals, exhibiting good stability. However, the reaction temperature was 130℃, requiring a large catalyst dosage. The highest nitrobenzene conversion rate was 99.8%, and the highest selectivity for aminophenol was 88.6%. Chinese patent CN117960225A disclosed a graphitic carbon nitride-encapsulated supported noble metal catalyst. The catalyst preparation process was complex, and the highest selectivity for aminophenol reached 85.1%. The use of surfactants in the reaction increased the difficulty of subsequent product separation.

[0004] To address the problems of metal loss, rapid catalyst deactivation, low catalyst activity, and poor selectivity in the selective hydrogenation of nitrobenzene to p-aminophenol, this invention presents a P-targeted carbon-encapsulated metal catalyst. At a feed ratio of m... NB:m M@PC Under the conditions of 10-100, reaction temperature 60-120℃, reaction pressure 0.6-2.0MPa, and sulfuric acid solution concentration 1.0-3.0M, the conversion rate of nitrobenzene is 100%, and the selectivity for aminophenol is the highest at 95.42%. Summary of the Invention

[0005] The purpose of this invention is to provide a P-targeted carbon-encapsulated noble metal catalyst with superior catalytic performance and acid resistance, its preparation method, and its application in the hydrogenation rearrangement of nitrobenzene to generate p-aminophenol. The catalyst preparation method is simple, green, and efficient.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0007] The first part of this invention provides a method for preparing a P-doped carbon-encapsulated noble metal catalyst, comprising the following steps:

[0008] (1) Disperse the noble metal precursor solution and the P-containing organic ligand in a solvent, reflux and stir in a water bath at 60-90℃ for 1-5 hours, filter, and separate the noble metal organic coordination complex crystal for subsequent preparation. The mother liquor is recycled. The noble metal in the noble metal precursor is Pt, Pd, Rh or Ru.

[0009] (2) Disperse the noble metal organic coordination complex crystal prepared in step (1) in a carbohydrate compound solution, and heat and stir in a water bath at 30-90℃ for 0.5-2h to obtain sample A;

[0010] (3) Add activated carbon to sample A obtained in step (2), heat and stir in a water bath at 30-90℃ for 2-6 hours to obtain sample B;

[0011] (4) Transfer the sample B obtained in step (3) into a hydrothermal reactor and hydrothermally react at 160-200℃ for 6-10h. After cooling to room temperature, open the hydrothermal reactor, filter and wash the hydrothermal product to obtain the M@PC catalyst precursor.

[0012] (5) Vacuum dry the M@PC catalyst precursor;

[0013] (6) The dried M@PC catalyst precursor is placed in a tube furnace and heated to 80-120℃ at a gas flow rate of 10-50 mL / min under an inert atmosphere and a heating rate of 1-20℃ / min. The temperature is held for 1-3 h, and then heated to 400-800℃ at a heating rate of 1-20℃ / min and held for 2-6 h to prepare the P-doped carbon-encapsulated noble metal catalyst.

[0014] Preferably, the noble metal precursor used in step (1) is one or more of H₂PtCl₆·6H₂O, PdCl₂, RhCl₃·3H₂O, and RuCl₃·3H₂O, which are prepared into a solution with a concentration preferably of 0.005-0.05 g / mL. The H₂PtCl₆, RhCl₃, and RuCl₃ solutions are prepared by directly dissolving the above metal precursors in water. The chloropalladium acid solution is prepared by dissolving PdCl₂ in 10 wt% hydrochloric acid solution.

[0015] Preferably, the P-containing organic ligand in step (1) is triphenylphosphine.

[0016] Preferably, in step (1), n 含P有机配体 :n 贵金属 =2.0-5.0, where n 贵金属 It refers to the amount of precious metal elements contained in the precious metal precursor solution.

[0017] Preferably, the solvent in step (1) is one of methanol or ethanol, and more preferably the ratio of the solvent to the P-containing organic ligand is 30-800 mL / g.

[0018] Preferably, the organometallic coordination complex obtained after filtration and washing in step (1) is: bis(triphenylphosphine)platinum chloride and bis(triphenylphosphine)palladium chloride.

[0019] Preferably, in step (2), the carbohydrate compound is one of glucose, fructose, and sucrose, and the solvent in the carbohydrate compound solution is water, wherein m 糖类化合物 V 溶剂 =1g:50-200mL, m 糖类聚合物(g) :m 活性炭(g) =1:5-10.

[0020] Preferably, the activated carbon in step (3) is one of coconut shell activated carbon or wood activated carbon, and more preferably, the activated carbon has a specific surface area of ​​800 m² or greater. 2 g -1 .

[0021] Preferably, in step (3), sample A and activated carbon are mixed according to m 贵金属 :m 活性炭 = 1:20-100 feeding ratio, where m 贵金属 This refers to the mass of precious metal elements contained in sample A.

[0022] Preferably, the solvent used for washing in step (4) is one or more of methanol, ethanol and deionized water.

[0023] Preferably, the vacuum drying conditions in step (5) are: drying in a vacuum oven at 40-120℃ for 6-14 hours.

[0024] In a second aspect, the present invention provides a P-doped carbon-encapsulated noble metal catalyst prepared according to the preparation method described in the first aspect.

[0025] The M@PC catalyst prepared by this invention has a catalyst particle size of 3-20 nm.

[0026] Thirdly, the present invention provides an application of the P-doped carbon-encapsulated noble metal catalyst described in the second aspect in the hydrogenation rearrangement of nitrobenzene to prepare p-aminophenol.

[0027] In this invention, the reaction of nitrobenzene hydrogenation rearrangement to produce p-aminophenol is carried out in a high-pressure micro-reactor.

[0028] The specific application process is as follows: Nitrobenzene and the catalyst are added to the polytetrafluoroethylene liner of the reactor at a certain feeding ratio. A pre-prepared sulfuric acid aqueous solution is added, the reactor is sealed, and the air inside the reactor is replaced with hydrogen. After ensuring that the air inside the reactor is completely replaced, hydrogen is introduced, the reaction temperature is set, and after the reactor is heated to the set reaction temperature, the stirring is turned on. After the hydrogen pressure stabilizes for 0.5-1 hours, a certain amount of hydrogen is released, and the reaction continues for 1-3 hours. After the reaction is completed, heating and stirring are stopped. After the reactor temperature drops to room temperature, the excess gas inside the reactor is released, the catalyst is separated by filtration, and the liquid sample is diluted for product analysis.

[0029] As a preferred option, the reaction conditions are: reaction pressure 0.6-2.0 MPa, reaction temperature 60-120℃, sulfuric acid aqueous solution concentration 1-3M; after the hydrogen pressure is stabilized for 0.5-1h, the hydrogen pressure is released to 0.4-0.1 MPa.

[0030] As a preferred option, the feeding ratio m NB :m 催化剂 =10-100.

[0031] The catalyst preparation method of this invention involves complexing a noble metal with a phosphorus-containing organic ligand. After washing and filtration, the noble metal-organic coordination complex crystal and activated carbon are sequentially dispersed in a carbohydrate compound solution. Hydrothermal treatment combines the metal-organic coordination complex crystal, carbohydrate compound, and activated carbon. Carbonization completely encapsulates the metal within the carbon layer. Compared with the prior art, the advantages of this invention are:

[0032] (1) The catalyst preparation method is simple, green, efficient, and the raw materials are readily available and inexpensive. The catalyst complexes the metal with organic ligands, thereby enriching heterogeneous elements on the carbon layer structure near the metal, adjusting the electron distribution between the carbon layer and the metal, and improving the catalytic performance of the catalyst.

[0033] (2) The prepared P-doped activated carbon-encapsulated noble metal catalyst has a fully encapsulated structure, exhibiting excellent acid resistance and catalytic performance. The metal coordinates with the ligands, and the strong coordination bonds have a strong interaction with the metal. After carbonization, a dense carbon shell is formed, protecting the metal from leaching. No significant deactivation was observed after 30 cycles of catalyst reuse.

[0034] (3) The encapsulated catalyst effectively coordinates the hydrogenation and molecular rearrangement reaction rates of the noble metal catalyst, and the conversion rate of nitrobenzene to p-aminophenol can reach 100%, with a selectivity of 95.42%. Attached Figure Description

[0035] Figure 1 This is a TEM image of the Pt@PC catalyst prepared in Example 1.

[0036] Figure 2 This is a test diagram of the Pt@PC catalyst prepared in Example 1. Detailed Implementation

[0037] The present invention will be further illustrated by specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0038] Unless otherwise specified in the embodiments of this invention, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained through conventional technical means or commercially available.

[0039] The wood-based activated carbon used in Examples 1-12 has a specific surface area of ​​1750 m². 2 / g, the wood-based activated carbon used in Examples 13-18 has a specific surface area of ​​1450m². 2 / g, the wood-based activated carbon used in Examples 19-24 has a specific surface area of ​​1020 m². 2 / g, the example uses coconut shell activated carbon with a specific surface area of ​​880m². 2 / g, the activated carbon used in the comparative examples was all wood-based activated carbon with a specific surface area of ​​1750m². 2 / g.

[0040] The precious metals used in the examples are: chloroplatinic acid hexahydrate (Aladdin, AR, Pt≥7.5%) and palladium chloride (Shanghai Bid Pharmaceutical Technology Co., Ltd., 99%).

[0041] The examples used triphenylphosphine (Shanghai Titan Technology Co., Ltd., purity ≥99%), nitrobenzene (Shanghai Titan Technology Co., Ltd., purity ≥99%), sulfuric acid (Sinopharm Group, 95-95%), ethanol (Shanghai Titan Technology Co., Ltd., analytical grade), methanol (Shanghai Titan Technology Co., Ltd., analytical grade), and deionized water.

[0042] Example 1

[0043] 1.8 mL of chloroplatinic acid solution with a Pt content of 0.05 g / mL was dispersed in 30 mL of ethanol solution. 0.3668 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a 60°C water bath for 3 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.3 g of glucose was dissolved in 60 mL of deionized water, and the complex crystals were added. The mixture was stirred in a 30°C water bath for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a 30°C water bath for 4 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200°C for 6 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pt@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 80°C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120℃ at a flow rate of 30 mL / min N2 and a rate of 5℃ / min, and held for 3 h. Then, it was heated to 600℃ at a rate of 5℃ / min and held for 4 h. This yielded the Pt@PC catalyst. 0.5 g of the Pt@PC catalyst was weighed into a beaker, and 50 mL of 3.0 M HCl solution was added. After stirring at room temperature for 4 hours, the supernatant was collected, and the alumina-assay (AAS) was measured. No metal signal was detected in the hydrochloric acid washing solution of the catalyst.

[0044] 0.8g of nitrobenzene and 0.04g of catalyst were fed at a ratio of m NB :m Pt@PC =20 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.0 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 91.44%.

[0045] Example 2

[0046] Disperse 6.0 mL of chloroplatinic acid solution with a Pt content of 0.005 g / mL in 30 mL of ethanol solution, add 0.1222 g of triphenylphosphine, reflux and stir in a water bath at 70 °C for 3 h, filter, and use the separated crystals for subsequent preparations; the mother liquor is recycled. Dissolve 0.3 g of glucose in 60 mL of deionized water, add the complex crystals, and stir in a water bath at 30 °C for 2 h. Then add 3 g of wood-based activated carbon and stir in a water bath at 30 °C for 4 h. Transfer to a hydrothermal reactor and hydrothermally react at 180 °C for 8 h. After cooling to room temperature, open the hydrothermal reactor, filter the hydrothermal product, wash with deionized water, and obtain the Pt@PC catalyst precursor. Dry the Pt@PC catalyst precursor in a vacuum oven at 60 °C for 12 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 80°C at a flow rate of 50 mL / min N2 and a rate of 2°C / min, and held at that temperature for 2 h. Then, it was heated to 800°C at a rate of 5°C / min and held at that temperature for 3 h. The Pt@PC catalyst was thus prepared.

[0047] 0.8g of nitrobenzene and 0.04g of catalyst were fed at a ratio of m NB :m Pt@PC =20 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.0 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 86.21%.

[0048] Example 3

[0049] Disperse 3.0 mL of chloroplatinic acid solution with a Pt content of 0.05 g / mL in 30 mL of ethanol solution, add 0.6117 g of triphenylphosphine, and reflux in a water bath at 60 °C for 3 h. Filter, and use the separated crystals for subsequent preparations; the mother liquor is recycled. Dissolve 0.6 g of glucose in 60 mL of deionized water, add the complex crystals, and stir in a water bath at 30 °C for 2 h. Then add 3 g of wood-based activated carbon and stir in a water bath at 30 °C for 4 h. Transfer to a hydrothermal reactor and hydrothermally react at 160 °C for 10 h. After cooling to room temperature, open the hydrothermal reactor, filter the hydrothermal product, wash with deionized water, and obtain the Pt@PC catalyst precursor. Dry the Pt@PC catalyst precursor in a vacuum oven at 40 °C for 14 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 1°C / min, and held at that temperature for 3 h. Then, it was heated to 800°C at a rate of 3°C / min and held at that temperature for 3 h. The Pt@PC catalyst was thus prepared.

[0050] 0.5g of nitrobenzene and 0.01g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.5 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.1 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 90.11%.

[0051] Example 4

[0052] Disperse 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL in 30 mL of ethanol solution, add 0.3202 g of triphenylphosphine, and reflux in a water bath at 90 °C for 3 h. Filter, and use the separated crystals for subsequent preparations; the mother liquor is recycled. Dissolve 0.3 g of glucose in 60 mL of deionized water, add the complex crystals, and stir in a water bath at 60 °C for 2 h. Then add 3 g of wood-based activated carbon and stir in a water bath at 60 °C for 4 h. Transfer to a hydrothermal reactor and hydrothermally react at 200 °C for 6 h. After cooling to room temperature, open the hydrothermal reactor, filter the hydrothermal product, wash with deionized water, and obtain the Pt@PC catalyst precursor. Dry the Pt@PC catalyst precursor in a vacuum oven at 120 °C for 6 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120℃ at a flow rate of 30 mL / min N2 and a rate of 10℃ / min, and held at that temperature for 3 h. Then, it was heated to 400℃ at a rate of 10℃ / min and held at that temperature for 6 h. The Pt@PC catalyst was thus prepared.

[0053] 0.5g of nitrobenzene and 0.05g of catalyst were mixed according to the feeding ratio m. NB :m Pt@PC =10 PTFE liner of the reactor was added, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas at a pressure of 1.0 MPa was introduced. The reaction temperature was set to 90 °C. After the reactor reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. NB conversion was 100%, and the selectivity for p-aminophenol was 89.52%.

[0054] Example 5

[0055] Disperse 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL in 30 mL of ethanol solution, add 0.3523 g of triphenylphosphine, and reflux in a water bath at 70 °C for 3 h. Filter, and use the separated crystals for subsequent preparations; the mother liquor is recycled. Dissolve 0.3 g of glucose in 60 mL of deionized water, add the complex crystals, and stir in a water bath at 90 °C for 1 h. Then add 3 g of wood-based activated carbon and stir in a water bath at 90 °C for 5 h. Transfer to a hydrothermal reactor and hydrothermally react at 200 °C for 6 h. After cooling to room temperature, open the hydrothermal reactor, filter the hydrothermal product, and wash with deionized water to obtain the Pt@PC catalyst precursor. Dry the Pt@PC catalyst precursor in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120℃ at a flow rate of 30 mL / min N2 and a rate of 20℃ / min, and held for 3 h. Then, it was heated to 600℃ at a rate of 20℃ / min and held for 4 h. The Pt@PC catalyst was thus prepared.

[0056] 0.4g of nitrobenzene and 0.02g of catalyst were mixed at a feed ratio of m. NB :m Pt@PC =20 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.0 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 1 hour, the hydrogen gas was released to 0.4 MPa, and the reaction continued for 2 hours. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 88.54%.

[0057] Example 6

[0058] 3.0 mL of chloroplatinic acid solution with a Pt content of 0.05 g / mL was dispersed in 50 mL of ethanol solution. 1.0080 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 90 °C for 3 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.3 g of glucose was dissolved in 60 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 30 °C for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 30 °C for 4 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 6 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pt@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 600°C at a rate of 5°C / min and held at that temperature for 4 h. The Pt@PC catalyst was thus prepared.

[0059] 1.0g of nitrobenzene and 0.01g of catalyst were added at a feeding ratio of m. NB :m Pt@PC =100% of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas at a pressure of 1.5 MPa was introduced. The reaction temperature was set to 60 °C. After the reactor reached the set temperature, the stirrer was turned on at 1200 rpm. After the hydrogen pressure stabilized for 1 hour, the hydrogen gas was released down to 0.2 MPa, and the reaction continued for 3 hours. Heating and stirring were then stopped. After the reactor temperature dropped to room temperature, excess gas was released, the catalyst was separated by filtration, and the liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 89.60%.

[0060] Example 7

[0061] 2.5 mL of chloropalladium acid solution with a Pd content of 0.0365 g / mL was dispersed in 30 mL of ethanol solution. 0.6202 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 70 °C for 3 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.3 g of glucose was dissolved in 60 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 60 °C for 1 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 60 °C for 5 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 6 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pd@PC catalyst precursor. The Pd@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120℃ at a flow rate of 30 mL / min N2 and a rate of 5℃ / min, and held for 3 h. Then, it was heated to 600℃ at a rate of 5℃ / min and held for 4 h. This yielded the Pd@PC catalyst. 0.5 g of the Pd@PC catalyst was weighed into a beaker, and 50 mL of 3.0 M HCl solution was added. After stirring at room temperature for 4 hours, the supernatant was collected, and the alumina-assay (AAS) was measured. No metal signal was detected in the hydrochloric acid washing solution of the catalyst.

[0062] 1.0g of nitrobenzene and 0.1g of catalyst were added at a feeding ratio of m. NB :m Pd@PC =10 PTFE liner was added to the reactor, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.2 MPa. The reaction temperature was set to 100 °C. After the reactor reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The NB conversion rate was 100%, and the selectivity for p-aminophenol was 93.22%.

[0063] Example 8

[0064] Disperse 0.82 mL of a chloropalladium acid solution with a Pd content of 0.0365 g / mL in 60 mL of ethanol solution, add 0.2305 g of triphenylphosphine, and reflux in a water bath at 60 °C for 3 h. Filter, and use the separated crystals for subsequent preparations; the mother liquor is recycled. Dissolve 0.3 g of glucose in 60 mL of deionized water, add the complex crystals, and stir in a water bath at 90 °C for 0.5 h. Then add 3 g of wood-based activated carbon and stir in a water bath at 90 °C for 3 h. Transfer to a hydrothermal reactor and hydrothermally react at 180 °C for 8 h. After cooling to room temperature, open the hydrothermal reactor, filter the hydrothermal product, wash with deionized water, and obtain the Pd@PC catalyst precursor. Dry the Pd@PC catalyst precursor in a vacuum oven at 80 °C for 10 h. The dried Pd@PC precursor was placed in a tube furnace and heated to 120℃ at a flow rate of 10 mL / min N2 and a holding time of 3 h. Then, it was heated to 600℃ at a heating rate of 1℃ / min and held for 4 h. The Pd@PC catalyst was thus prepared.

[0065] 0.5g of nitrobenzene and 0.05g of catalyst were mixed according to the feeding ratio m. NB :m Pd@PC =10 PTFE liner was added to the reactor, along with 25 mL of 3.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Hydrogen gas was then introduced at a pressure of 0.6 MPa. The reaction temperature was set to 80 °C. Once the reactor reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 1 hour, the hydrogen was released to 0.1 MPa, and the reaction continued for 3 hours. Heating and stirring were then stopped. After the reactor temperature cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The NB conversion rate was 100%, and the selectivity for p-aminophenol was 86.50%.

[0066] Example 9

[0067] 4.11 mL of a chloropalladium acid solution with a Pd content of 0.0365 g / mL was dispersed in 60 mL of ethanol solution. 1.0084 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 70 °C for 5 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.6 g of glucose was dissolved in 60 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 60 °C for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 60 °C for 5 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 6 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pd@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 40 °C for 14 h. The dried Pd@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 600°C at a rate of 5°C / min and held at that temperature for 4 h. The Pd@PC catalyst was thus prepared.

[0068] 1.0g of nitrobenzene and 0.01g of catalyst were mixed at a feed ratio of m. NB :m Pd@PC =100% of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 3.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.5 MPa. The reaction temperature was set to 120 °C. After the reactor reached the set temperature, the stirrer was turned on at a speed of 1200 r / min. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.1 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature dropped to room temperature, excess gas was released, the catalyst was separated by filtration, and the liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 93.18%.

[0069] Example 10

[0070] Disperse 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL in 30 mL of methanol solution, add 0.3325 g of triphenylphosphine, and reflux in a water bath at 60 °C for 1 h. Filter, and use the separated crystals for subsequent preparations; the mother liquor is recycled. Dissolve 0.3 g of glucose in 60 mL of deionized water, add the complex crystals, and stir in a water bath at 30 °C for 2 h. Then add 3 g of wood-based activated carbon and stir in a water bath at 30 °C for 4 h. Transfer to a hydrothermal reactor and hydrothermally react at 200 °C for 6 h. After cooling to room temperature, open the hydrothermal reactor, filter the hydrothermal product, wash with deionized water, and obtain the Pt@PC catalyst precursor. Dry the Pt@PC catalyst precursor in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 800°C at a rate of 5°C / min and held at that temperature for 2 h. The Pt@PC catalyst was thus prepared.

[0071] 1.0g of nitrobenzene and 0.02g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 3.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 2.0 MPa. The reaction temperature was set to 60 °C. After the reactor reached the set temperature, the stirrer was turned on at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.4 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 86.48%.

[0072] Example 11

[0073] 1.8 mL of ruthenium chloride solution with a Ru content of 0.05 g / mL was dispersed in 50 mL of ethanol solution. 0.9178 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 60 °C for 1 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.6 g of glucose was dissolved in 80 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 30 °C for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 30 °C for 4 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 6 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Ru@PC catalyst precursor. The Ru@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Ru@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 800°C at a rate of 5°C / min and held at that temperature for 2 h. The Ru@PC catalyst was thus prepared.

[0074] 2.0g of nitrobenzene and 0.04g of catalyst were mixed at a feeding ratio of m. NB :m Ru@PC =50 ppm of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 1.5 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 2.0 MPa. The reaction temperature was set to 80 °C. After the reactor reached the set temperature, the stirrer was turned on at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 90.85%.

[0075] Example 12

[0076] 1.8 mL of rhodium chloride solution with a concentration of 0.05 g / mL was dispersed in 30 mL of ethanol solution. 0.8125 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 60 °C for 2 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.5 g of glucose was dissolved in 80 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 30 °C for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 30 °C for 4 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 6 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Rh@PC catalyst precursor. The Rh@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Rh@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 800°C at a rate of 5°C / min and held at that temperature for 2 h. The Rh@PC catalyst was thus prepared.

[0077] 1.0g of nitrobenzene and 0.02g of catalyst were mixed at a feeding ratio of m. NB :m Rh@PC =50 ppm of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.2 MPa. The reaction temperature was set to 90 °C. After the reactor reached the set temperature, the stirrer was turned on at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 89.78%.

[0078] Example 13

[0079] 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL was dispersed in 30 mL of methanol solution. 0.6011 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 60 °C for 2 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.5 g of glucose was dissolved in 80 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 30 °C for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 30 °C for 4 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 6 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pt@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 2 h. Then, it was heated to 500°C at a rate of 5°C / min and held at that temperature for 5 h. The Pt@PC catalyst was thus prepared.

[0080] 0.5g of nitrobenzene and 0.01g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the reactor reached the set temperature, the stirrer was turned on at a speed of 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature dropped to room temperature, excess gas was released, the catalyst was separated by filtration, and the liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 90.89%.

[0081] Example 14

[0082] 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL was dispersed in 30 mL of methanol solution. 0.2445 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 60 °C for 2 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.3 g of glucose was dissolved in 20 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 30 °C for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 30 °C for 4 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 8 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pt@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 800°C at a rate of 5°C / min and held at that temperature for 2 h. The Pt@PC catalyst was thus prepared.

[0083] 0.5g of nitrobenzene and 0.01g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the reactor reached the set temperature, the stirrer was turned on at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.2 MPa, and the reaction continued for 2 h. Heating and stirring were then stopped. After the reactor temperature dropped to room temperature, excess gas was released, the catalyst was separated by filtration, and the liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 91.54%.

[0084] Example 15

[0085] 1.4 mL of chloroplatinic acid solution with a Pt content of 0.0367 g / mL was dispersed in 50 mL of ethanol solution. 0.3190 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a 90°C water bath for 2 hours. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.6 g of glucose was dissolved in 120 mL of deionized water, and the complex crystals were added. The mixture was stirred in a 30°C water bath for 2 hours. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a 30°C water bath for 5 hours. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200°C for 8 hours. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pt@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 90°C for 10 hours. The dried Pt@PC precursor was placed in a tube furnace and heated to 120℃ at a flow rate of 50 mL / min N2 and a holding time of 2℃ / min. The temperature was then increased to 800℃ at a further increase rate of 2℃ / min and held for 3 hours. This yielded the Pt@PC catalyst.

[0086] 0.5g of nitrobenzene and 0.01g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 2.0 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 120 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 1 hour, the hydrogen gas was released down to 0.3 MPa, and the reaction continued for another hour. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 91.22%.

[0087] Example 16

[0088] 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL was dispersed in 50 mL of methanol solution. 0.3325 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 60 °C for 2 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.6 g of glucose was dissolved in 90 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 30 °C for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 30 °C for 5 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 6 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pt@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 400°C at a rate of 5°C / min and held at that temperature for 6 h. The Pt@PC catalyst was thus prepared.

[0089] 0.5g of nitrobenzene and 0.01g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 0.8 MPa. The reaction temperature was set to 90 °C. After the reactor reached the set temperature, the stirrer was turned on at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.1 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 88.54%.

[0090] Example 17

[0091] Disperse 0.82 mL of chloroplatinic acid solution with a Pt content of 0.0367 g / mL in 50 mL of ethanol solution, add 0.0856 g of triphenylphosphine, reflux and stir in a water bath at 60 °C for 1 h, filter, and use the separated crystals for subsequent preparations; the mother liquor is recycled. Dissolve 0.3 g of glucose in 40 mL of deionized water, add the complex crystals, and stir in a water bath at 30 °C for 2 h. Then add 3 g of wood-based activated carbon and stir in a water bath at 30 °C for 4 h. Transfer to a hydrothermal reactor and hydrothermally react at 200 °C for 6 h. After cooling to room temperature, open the hydrothermal reactor, filter the hydrothermal product, wash with deionized water, and obtain the Pt@PC catalyst precursor. Dry the Pt@PC catalyst precursor in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120℃ at a flow rate of 50 mL / min N2 and a rate of 10℃ / min, and held at that temperature for 3 h. Then, it was heated to 800℃ at a rate of 10℃ / min and held at that temperature for 5 h. The Pt@PC catalyst was thus prepared.

[0092] 0.6g of nitrobenzene and 0.02g of catalyst were mixed at a feed ratio of m. NB :m Pt@PC =30 was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 1.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 100℃. After the reactor reached the set temperature, the stirrer was turned on at 1200 r / min. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.1 MPa, and the reaction continued for 2 h. Heating and stirring were then stopped. After the reactor temperature dropped to room temperature, excess gas was released, the catalyst was separated by filtration, and the liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 89.56%.

[0093] Example 18

[0094] Disperse 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL in 30 mL of ethanol solution, add 0.3356 g of triphenylphosphine, reflux and stir in a water bath at 60 °C for 1 h, filter, and use the separated crystals for subsequent preparations; the mother liquor is recycled. Dissolve 0.3 g of glucose in 60 mL of deionized water, add the complex crystals, and stir in a water bath at 30 °C for 2 h. Then add 3 g of wood-based activated carbon and stir in a water bath at 30 °C for 4 h. Transfer to a hydrothermal reactor and hydrothermally react at 200 °C for 6 h. After cooling to room temperature, open the hydrothermal reactor, filter the hydrothermal product, wash with deionized water, and obtain the Pt@PC catalyst precursor. Dry the Pt@PC catalyst precursor in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 800°C at a rate of 5°C / min and held at that temperature for 2 h. The Pt@PC catalyst was thus prepared.

[0095] 0.5g of nitrobenzene and 0.05g of catalyst were mixed according to the feeding ratio m. NB :m Pt@PC =10 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 2.0 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Hydrogen gas was then introduced at a pressure of 0.6 MPa. The reaction temperature was set to 60 °C. Once the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the pressure was reduced to 0.1 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The NB conversion rate was 100%, and the selectivity for p-aminophenol was 92.55%.

[0096] Example 19

[0097] 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL was dispersed in 50 mL of ethanol solution. 0.2866 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 60 °C for 1 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.6 g of glucose was dissolved in 60 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 30 °C for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 30 °C for 4 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 6 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pt@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120℃ at a flow rate of 10 mL / min N2 and a holding time of 3 h. Then, it was heated to 600℃ at a heating rate of 1℃ / min and held for 6 h. The Pt@PC catalyst was thus prepared.

[0098] 1.0g of nitrobenzene and 0.02g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.0 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.1 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 90.36%.

[0099] Example 20

[0100] Disperse 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL in 30 mL of ethanol solution, add 0.3325 g of triphenylphosphine, reflux and stir in a water bath at 60 °C for 1 h, filter, and use the separated crystals for subsequent preparations; the mother liquor is recycled. Dissolve 0.6 g of glucose in 120 mL of deionized water, add the complex crystals, and stir in a water bath at 90 °C for 2 h. Then add 3 g of wood-based activated carbon and stir in a water bath at 90 °C for 4 h. Transfer to a hydrothermal reactor and hydrothermally react at 200 °C for 6 h. After cooling to room temperature, open the hydrothermal reactor, filter the hydrothermal product, wash with deionized water, and obtain the Pt@PC catalyst precursor. Dry the Pt@PC catalyst precursor in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 400°C at a rate of 5°C / min and held at that temperature for 6 h. The Pt@PC catalyst was thus prepared.

[0101] 0.5g of nitrobenzene and 0.01g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 60 °C. After the reactor reached the set temperature, the stirrer was turned on at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.1 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature dropped to room temperature, excess gas was released, the catalyst was separated by filtration, and the liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 89.65%.

[0102] Example 21

[0103] 2.47 mL of a chloropalladium acid solution with a Pd content of 0.0365 g / mL was dispersed in 40 mL of methanol solution. 1.0112 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 60 °C for 1 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.6 g of glucose was dissolved in 90 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 30 °C for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 30 °C for 4 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 6 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pd@PC catalyst precursor. The Pd@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Pd@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 550°C at a rate of 5°C / min and held at that temperature for 4 h. The Pd@PC catalyst was thus prepared.

[0104] 0.5g of nitrobenzene and 0.01g of catalyst were mixed at a feeding ratio of m. NB :m Pd@PC =50 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.0 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.2 MPa, and the reaction continued for 3 h. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 90.54%.

[0105] Example 22

[0106] 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL was dispersed in 60 mL of methanol solution. 0.4502 g of triphenylphosphine was added, and the mixture was refluxed and stirred in an 80°C water bath for 2 hours. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.4 g of glucose was dissolved in 60 mL of deionized water, and the complex crystals were added. The mixture was stirred in a 30°C water bath for 2 hours. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a 30°C water bath for 4 hours. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 180°C for 10 hours. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pt@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 120°C for 8 hours. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 600°C at a rate of 5°C / min and held at that temperature for 5 h. The Pt@PC catalyst was thus prepared.

[0107] 0.5g of nitrobenzene and 0.01g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.5 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas at a pressure of 1.0 MPa was introduced. The reaction temperature was set to 70 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.1 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 88.65%.

[0108] Example 23

[0109] 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL was dispersed in 40 mL of ethanol solution. 0.2985 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 60 °C for 2 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.4 g of glucose was dissolved in 60 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 30 °C for 2 h. Then, 3 g of wood-based activated carbon was added, and the mixture was stirred in a water bath at 30 °C for 4 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 180 °C for 10 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pt@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 600°C at a rate of 5°C / min and held at that temperature for 5 h. The Pt@PC catalyst was thus prepared.

[0110] 1.5g of nitrobenzene and 0.03g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 2.0 MPa. The reaction temperature was set to 90 °C. After the reactor reached the set temperature, the stirrer was turned on at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.1 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 89.42%.

[0111] Example 24

[0112] Disperse 1.8 mL of chloroplatinic acid solution with a Pt content of 0.05 g / mL in 100 mL of ethanol solution, add 0.5425 g of triphenylphosphine, reflux and stir in a water bath at 70 °C for 2 h, filter, and use the separated crystals for subsequent preparations; the mother liquor is recycled. Dissolve 0.3 g of glucose in 60 mL of deionized water, add the complex crystals, and stir in a water bath at 30 °C for 2 h. Then add 3 g of wood-based activated carbon and stir in a water bath at 30 °C for 4 h. Transfer to a hydrothermal reactor and hydrothermally react at 200 °C for 6 h. After cooling to room temperature, open the hydrothermal reactor, filter the hydrothermal product, wash with deionized water, and obtain the Pt@PC catalyst precursor. Dry the Pt@PC catalyst precursor in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held at that temperature for 3 h. Then, it was heated to 800°C at a rate of 5°C / min and held at that temperature for 2 h. The Pt@PC catalyst was thus prepared.

[0113] 1.0g of nitrobenzene and 0.01g of catalyst were mixed at a feed ratio of m. NB :m Pt@PC =100% of the catalyst was added to the polytetrafluoroethylene liner of the reactor, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.6 MPa. The reaction temperature was set to 80℃. After the reactor reached the set temperature, the stirrer was turned on at a speed of 1200 r / min. After the hydrogen pressure stabilized for 0.5 h, the hydrogen gas was released to 0.2 MPa, and the reaction continued for 2 h. Heating and stirring were then stopped. After the reactor temperature dropped to room temperature, excess gas was released, the catalyst was separated by filtration, and the liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 95.42%.

[0114] Example 25

[0115] 3.0 mL of chloroplatinic acid solution with a Pt content of 0.03 g / mL was dispersed in 80 mL of ethanol solution. 0.3254 g of triphenylphosphine was added, and the mixture was refluxed and stirred in a water bath at 60 °C for 1 h. After filtration, the separated crystals were used for subsequent preparations, and the mother liquor was recycled. 0.4 g of glucose was dissolved in 60 mL of deionized water, and the complex crystals were added. The mixture was stirred in a water bath at 30 °C for 2 h. Then, 3 g of coconut shell activated carbon was added, and the mixture was stirred in a water bath at 30 °C for 6 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 200 °C for 10 h. After cooling to room temperature, the hydrothermal reactor was opened, and the hydrothermal product was filtered and washed with deionized water to obtain the Pt@PC catalyst precursor. The Pt@PC catalyst precursor was dried in a vacuum oven at 80 °C for 10 h. The dried Pt@PC precursor was placed in a tube furnace and heated to 120°C at a flow rate of 30 mL / min N2 and a rate of 5°C / min, and held for 1 h. Then, it was heated to 700°C at a rate of 5°C / min and held for 3 h. The Pt@PC catalyst was thus prepared.

[0116] 0.5g of nitrobenzene and 0.01g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =50 ppm of the catalyst was added to a polytetrafluoroethylene liner in a reactor, along with 25 mL of 2.0 M sulfuric acid solution. The reactor was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the reactor reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, the hydrogen was released to 0.1 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reactor temperature cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 90.36%.

[0117] Example 26

[0118] The reusability of the P-doped activated carbon-encapsulated noble metal catalyst prepared in Example 1 in the hydrogenation rearrangement of nitrobenzene to prepare p-aminophenol was investigated. The reaction conditions were the same as in Example 1, and the results are as follows: Figure 2 As shown.

[0119] Comparative Example 1

[0120] Take 3.0 g of dried wood-based activated carbon at 120℃, stir in a water bath at 50℃ for 30 min, then add 2.4 mL of freshly prepared chloroplatinic acid solution with a Pt content of 0.0375 g / mL, stir in a water bath at 50℃ for 2 h, let stand, adjust the pH to 8 with NaOH, filter, transfer to a reaction vessel, add 30 mL of deionized water, purge with 1.00 MPa H2, and reduce at 90℃ and 1200 r / min for 2 h. After reduction, cool and filter to obtain the Pt / C catalyst. Weigh 0.5 g of Pt / C catalyst into a beaker, add 50 mL of 3.0 M HCl solution, stir at room temperature for 4 hours, take the clear liquid, and measure the AAS (Alkali Assay). The metal leaching rate in the catalyst is 26.75 wt%.

[0121] 1g of nitrobenzene and 0.05g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =20 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.5 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas at a pressure of 1.0 MPa was introduced. The reaction temperature was set to 80 °C. Once the vessel reached the set temperature, stirring was started at 1200 rpm. After the reaction was complete, heating and stirring were stopped. The reaction vessel was allowed to cool to room temperature, and excess gas was released. The catalyst was filtered to separate it, and a liquid sample was diluted for product analysis. The NB conversion rate was 100%, and the selectivity for p-aminophenol was 45.77%.

[0122] Comparative Example 2

[0123] Take 3.0 g of wood-based activated carbon dried at 120℃, stir in a water bath at 50℃ for 30 min, add 4.0 mL of chloroplatinic acid solution with a Pt content of 0.0375 g / mL, stir in a water bath at 50℃ for 2 h, let stand, adjust the pH to 8 with NaOH, filter, transfer to a reaction vessel, add 30 mL of deionized water, purge with 1.00 MPa H2, and reduce at a reaction temperature of 90℃ and a stirring speed of 1200 r / min for 2 h. After reduction, cool and filter to obtain the Pt / C catalyst.

[0124] 1g of nitrobenzene and 0.05g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC=20 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.5 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas at a pressure of 1.0 MPa was introduced. The reaction temperature was set to 80 °C. Once the vessel reached the set temperature, stirring was started at 1200 rpm. After the reaction was complete, heating and stirring were stopped. The reaction vessel was allowed to cool to room temperature, and excess gas was released. The catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The NB conversion rate was 100%, and the selectivity for p-aminophenol was 60.25%.

[0125] Comparative Example 3

[0126] P-doped activated carbon was prepared by impregnation. 0.3668 g of triphenylphosphine was dispersed in 30 mL of ethanol and completely dissolved. Then, 3.0 g of wood-based activated carbon was added. After sonication for half an hour, the mixture was dried in a forced-air oven at 120 °C for 2 hours, followed by holding at 550 °C for 4 hours under a nitrogen atmosphere at a heating rate of 5 °C / min. This yielded a P-doped activated carbon support (PC).

[0127] Take 1.0 g of PC carrier, stir in a water bath at 50℃ for 30 min, add 0.8 mL of chloroplatinic acid solution with a 0.0375 g / mL LPt content, stir in a water bath at 50℃ for 2 h, let stand, adjust pH to 8 with NaOH, filter, transfer to a reaction vessel, add an appropriate amount of deionized water, and purge with 1.00 MPa H2O. 2， The reaction was carried out at a reaction temperature of 90℃ and a stirring speed of 1200 r / min for 2 h. After reduction, the mixture was cooled and filtered to obtain Pt / PC.

[0128] 1g of nitrobenzene and 0.05g of catalyst were mixed at a feeding ratio of m. NB :m Pt@PC =20 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.5 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 78.22%.

[0129] Comparative Example 4

[0130] 4 g of glucose was dissolved in 40 mL of deionized water, and 1 g of Pt / C prepared in Comparative Example 1 was added. After stirring at room temperature for 2 hours, the mixture was placed in a hydrothermal reactor and hydrothermally heated at 200 °C for 6 hours. After cooling, the mixture was rinsed with deionized water and dried under vacuum at 60 °C for 12 hours to obtain Pt / C@GLU. The temperature was increased to 120 °C at a flow rate of 30 mL / min N2 and held for 3 hours. Then, the temperature was increased to 600 °C at a rate of 5 °C / min and held for 4 hours to obtain the catalyst Pt / C@C.

[0131] 0.8g of nitrobenzene and 0.04g of catalyst were fed at a ratio of m NB :m Pt@PC =20 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.5 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 55.26%.

[0132] Comparative Example 5

[0133] 0.8 g of nitrobenzene and 0.04 g of commercial 3 wt% Pt / C catalyst were mixed at a feed ratio of m NB :m Pt@PC =20 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.5 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. Excess gas was released after the reaction vessel cooled to room temperature. The catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The NB conversion rate was 100%, and the selectivity for p-aminophenol was 24.08%.

[0134] Comparative Example 6

[0135] Take 3.0g of dried wood-based activated carbon (dried at 120℃), stir in a water bath at 50℃ for 30min, then add freshly prepared 2.4mL chloropalladium acid solution (LPd content 0.0375g / mL), stir in a water bath at 50℃ for 2h, let stand, adjust pH to 8 with NaOH, filter, transfer to a reaction vessel, add appropriate amount of deionized water, and purge with 1.00MPa H2O.2， The catalyst was reduced at a reaction temperature of 90℃ and a stirring speed of 1200 r / min for 2 h. After reduction, the catalyst was cooled and filtered to obtain the Pd / C catalyst.

[0136] 0.8g of nitrobenzene and 0.04g of catalyst were fed at a ratio of m NB :m Pt@PC =20 ppm of PTFE-lined catalyst was added to a reaction vessel, along with 25 mL of 1.5 M sulfuric acid solution. The reaction vessel was sealed, and the air inside was replaced with hydrogen gas until complete replacement. Then, hydrogen gas was introduced at a pressure of 1.0 MPa. The reaction temperature was set to 80 °C. After the vessel reached the set temperature, stirring was started at 1200 rpm. After the hydrogen pressure stabilized for 0.5 h, hydrogen gas was released to 0.2 MPa, and the reaction continued for 1 h. Heating and stirring were then stopped. After the reaction vessel cooled to room temperature, excess gas was released, the catalyst was separated by filtration, and a liquid sample was diluted for product analysis. The conversion rate of NB was 100%, and the selectivity for p-aminophenol was 27.08%.

Claims

1. A method for preparing a P-doped carbon-encapsulated noble metal catalyst, characterized in that: The preparation method includes the following steps: (1) The noble metal precursor solution and the P-containing organic ligand are dispersed in a solvent, refluxed in a water bath at 60-90 °C for 1-5 h, filtered, and the noble metal organic coordination complex crystals are separated for subsequent preparation. The mother liquor is recycled. The noble metal in the noble metal precursor is Pt, Pd, Rh or Ru. (2) Disperse the noble metal organic coordination complex crystals prepared in step (1) in a carbohydrate compound solution, and heat and stir in a water bath at 30-90 °C for 0.5-2 h to obtain sample A; (3) Add activated carbon to sample A obtained in step (2), heat and stir in a water bath at 30-90 ℃ for 2-6 h to obtain sample B; (4) Transfer the sample B obtained in step (3) into a hydrothermal reactor and hydrothermally react at 160-200 °C for 6-10 h. After cooling to room temperature, open the hydrothermal reactor, filter and wash the hydrothermal product to obtain the M@PC catalyst precursor. (5) Vacuum dry the M@PC catalyst precursor; (6) Place the dried M@PC catalyst precursor in a tube furnace, and heat it to 80-120 ℃ at a gas flow rate of 10-50 mL / min under an inert atmosphere, and hold it for 1-3 h. Then heat it to 400-800 ℃ at a heating rate of 1-20 ℃ / min and hold it for 2-6 hours to prepare the P-doped carbon-encapsulated noble metal catalyst.

2. The preparation method according to claim 1, characterized in that: The noble metal precursor used in step (1) is one or more of H2PtCl6·6H2O, PdCl2, RhCl3·3H2O, and RuCl3·3H2O.

3. The preparation method according to claim 1, characterized in that: The P-containing organic ligand in step (1) is triphenylphosphine.

4. The preparation method according to claim 1, characterized in that: In step (1), n 含P有机配体 :n 贵金属 =2.0-5.0, where n 贵金属 It refers to the amount of precious metal elements contained in the precious metal precursor solution.

5. The preparation method according to claim 1, characterized in that: The solvent mentioned in step (1) is one of methanol or ethanol.

6. The preparation method according to claim 1, characterized in that: In step (2), the carbohydrate compound is one of glucose, fructose, and sucrose, and the solvent in the carbohydrate compound solution is water, wherein m 糖类化合物 V 溶剂 =1g: 50-200mL, m 糖类聚合物 :m 活性炭 =1:5-10.

7. The preparation method according to claim 1, characterized in that: The activated carbon mentioned in step (3) is one of coconut shell or wood-based activated carbon, and the specific surface area of ​​the activated carbon is greater than or equal to 800 m². 2 g -1 .

8. The preparation method according to claim 1, characterized in that: In step (3), sample A and activated carbon are mixed according to m 贵金属 :m 活性炭 =1:20-100 feeding, where m 贵金属 This refers to the mass of precious metal elements contained in sample A.

9. A P-doped carbon-encapsulated noble metal catalyst prepared by the preparation method according to any one of claims 1-8.

10. The application of the P-doped carbon-encapsulated noble metal catalyst as described in claim 9 in the hydrogenation rearrangement of nitrobenzene to prepare p-aminophenol.

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