Glycine-derived nitrogen-doped carbon-coated platinum catalyst as well as preparation method and application thereof
By using a nitrogen-doped carbon-coated platinum catalyst derived from glycine, the problem of easy loss and poisoning of the precious metal Pt was solved, and efficient and stable preparation of p-aminophenol by hydrogenation rearrangement of nitrobenzene was achieved, improving the selectivity and yield of the catalyst.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-15
- Publication Date
- 2026-03-17
AI Technical Summary
In the existing catalytic hydrogenation method for preparing p-aminophenol from nitrobenzene, the precious metal Pt is easily lost and poisoned, the catalyst cost is high, the by-product control is difficult, and the selectivity and yield are low.
Using glycine as a single precursor, a glycine-derived nitrogen-doped carbon-coated platinum catalyst was prepared via a hydrothermal method. By controlling the carbon layer thickness, nitrogen doping amount, calcination atmosphere, and temperature, a uniform carbon coating layer was formed, which inhibited the migration and dissolution of Pt particles and provided catalytic active sites.
It improves the activity, selectivity and stability of the catalyst, reduces the loss of precious metals, lowers the cost of the catalyst, and enhances the catalytic performance in acidic environments.
Smart Images
Figure FT_1 
Figure SMS_1 
Figure SMS_2
Abstract
Description
(I) Technical Field
[0001] This invention relates to a glycine-derived nitrogen-doped carbon-coated platinum catalyst, its preparation method, and its application in the hydrogenation rearrangement of nitrobenzene to prepare p-aminophenol. (II) Background Technology
[0002] p-Aminophenol (PAP) is an important basic chemical raw material and fine chemical intermediate with huge global demand. It is widely used in the pharmaceutical, dye, rubber, and photographic industries. In addition, it can also be used as a lubricant additive, pesticide intermediate, and liquid crystal material intermediate.
[0003] The main industrial production methods for PAP include iron powder reduction, catalytic hydrogenation, phenol hydroxylation, and p-nitrochlorobenzene hydrolysis. Major global PAP producers have gradually phased out the iron powder method and switched to catalytic hydrogenation. Catalytic hydrogenation uses p-nitrophenol or nitrobenzene as raw materials, and reduces them by introducing hydrogen gas in the presence of a catalyst (such as Pd / C, Pt / C, Raney Ni, etc.). This method is cleaner and more environmentally friendly, and is currently the mainstream production process.
[0004] The catalytic hydrogenation of nitrobenzene to p-aminophenol is an important clean production process. Compared with the traditional iron powder reduction method (which is highly polluting and inefficient), it has significant advantages such as environmental friendliness, high selectivity, good atom economy, and ease of continuous production. Its core reaction principle involves the catalytic hydrogenation of nitrobenzene in an acidic aqueous solution to generate a phenylhydroxylamine intermediate, which then undergoes intramolecular rearrangement to produce p-aminophenol. However, the high leaching and poisoning of the precious metal Pt significantly increases catalyst costs, and the difficulty in controlling byproducts reduces the selectivity and yield of PAP. (III) Summary of the Invention
[0005] The purpose of this invention is to provide a glycine-derived nitrogen-doped carbon-coated platinum catalyst, its preparation method, and its application in the hydrogenation rearrangement of nitrobenzene to prepare p-aminophenol.
[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:
[0007] In a first aspect, the present invention provides a method for preparing a glycine-derived nitrogen-doped carbon-coated platinum catalyst, the preparation method comprising the following steps:
[0008] (1) Take a supported platinum catalyst, the supported platinum catalyst comprising a support and a metal active component supported on the support, the metal active component being Pt, and add it to a homogeneous glycine aqueous solution to disperse it evenly.
[0009] (2) Transfer the mixture obtained in step (1) to a reaction vessel for hydrothermal reaction. The hydrothermal reaction temperature is 100-150℃ and the hydrothermal reaction time is 10-20h.
[0010] (3) Cool the mixture obtained in step (2) to room temperature, collect the product by vacuum filtration, wash thoroughly with ethanol, and then dry under vacuum.
[0011] (4) Grind the dried product obtained in step (3) into a uniform powder, and then calcine it at a high temperature of 300-800℃ for 2-10h under an inert protective atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0012] In step (1) of this invention, the supported platinum catalyst can be uniformly dispersed in the glycine aqueous solution by means of stirring and ultrasound. Further, the mixture is stirred at a stirring rate of 400–600 rpm for 1–5 hours, and then continuously ultrasonicated at medium–high (40%–70%) power for 20–50 minutes to ensure uniform dispersion. It is understood that faster stirring speed, longer stirring time, higher ultrasonic power, and longer ultrasonic time are more conducive to achieving uniform dispersion of glycine on the surface of the supported platinum catalyst.
[0013] Further, in step (1), the feed ratio of the supported platinum catalyst to the glycine aqueous solution is calculated as follows: the feed ratio of the supported platinum catalyst to water is 3g:50-80mL, and the mass ratio of the supported platinum catalyst to glycine is 1:(0.3-2). Even further, the feed ratio of the supported platinum catalyst to water is 3g:80mL, and the mass ratio of the supported platinum catalyst to glycine is 1:1.5-2, with 1:2 being the most preferred.
[0014] In step (1) of this invention, the supported platinum catalyst can be a commercially available product or can be prepared according to literature. Further, in step (1), the support for the supported platinum catalyst is activated carbon, SiO2, or TiO2, and the platinum loading relative to the support is 1–5 wt%. Even further, the supported platinum catalyst is an activated carbon-supported platinum catalyst, and the platinum loading relative to the support is 5 wt%.
[0015] In step (2) of this invention, the hydrothermal reaction temperature is 100–150°C, and the hydrothermal reaction time is 10–20 h. Specifically, the hydrothermal reaction temperature can be 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, or any range between the two mentioned above. Preferably, the hydrothermal reaction temperature is 140–150°C, and more preferably 150°C. The hydrothermal reaction time can be 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, or any range between the two mentioned above. Preferably, the hydrothermal reaction time is 18–20 h, and more preferably 20 h.
[0016] Furthermore, in step (3), the vacuum drying temperature is 40–110°C and the vacuum drying time is 3–15 h.
[0017] In step (4) of this invention, the inert protective atmosphere is one or more of nitrogen, argon, and helium; the calcination temperature is 300–800°C; and the calcination time is 2–10 h. Specifically, the calcination temperature can be 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, or any range between the aforementioned two. Preferably, the calcination temperature is 700–800°C, and more preferably 800°C. The calcination time can be 2 h, 3 h, 4 h, or any range between the aforementioned two. Preferably, the calcination time is 2–3 h, and more preferably 3 h.
[0018] In a second aspect, the present invention provides a glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared according to the preparation method described in the first aspect.
[0019] Thirdly, the present invention provides the application of the glycine-derived nitrogen-doped carbon-coated platinum catalyst described in the second aspect in the hydrogenation rearrangement of nitrobenzene to prepare p-aminophenol.
[0020] Further, the specific method of the application is as follows: distilled water, 98wt% concentrated sulfuric acid, nitrobenzene, surfactant, and glycine-derived nitrogen-doped carbon-coated platinum catalyst are added to an acid-resistant high-pressure reactor in a mass ratio of 150-250:10-50:20-100:0.2-0.8:0.5-3. Hydrogen gas is introduced and a hydrogenation rearrangement reaction is carried out under stirring conditions to obtain the target product p-aminophenol.
[0021] Furthermore, the surfactant is hexadecyltrimethylammonium chloride.
[0022] Furthermore, the reaction temperature of the hydrogenation rearrangement reaction is 60–100°C, and the hydrogen pressure inside the reactor is 0.6–1.5 MPa.
[0023] This invention provides a method for preparing a glycine-derived nitrogen-doped carbon-coated platinum catalyst and its application in the hydrogenation rearrangement of nitrobenzene to prepare p-aminophenol. By controlling the carbon layer thickness, nitrogen doping amount, calcination atmosphere, calcination temperature, and calcination time, carbon layers with different nitrogen contents derived from glycine can be obtained. Based on the electronic effect between platinum and carbon materials, a catalyst with high activity, high selectivity, and high stability in sulfuric acid reaction medium is obtained.
[0024] Compared with the prior art, the present invention has the following advantages:
[0025] (1) The catalyst prepared in this invention uses glycine as a single precursor, containing both amino (nitrogen source) and carboxyl (carbon source) groups. During pyrolysis, it can be simultaneously carbonized and nitrogen-doped, avoiding the phase separation problem of heterogeneous doping. Simultaneously, the fixed intramolecular C / N ratio allows for uniform anchoring of nitrogen atoms within the carbon framework, reducing agglomeration and achieving atomic-level uniform dispersion. Furthermore, the small-molecule glycine exhibits good fluidity during pyrolysis and carbonization, easily forming a continuous coating layer on the surface of metal nanoparticles (such as Pt), effectively inhibiting metal sintering and leaching. Through the coordination of the amino group with the Pt precursor, uniform encapsulation and self-assembly of Pt nanoparticles into a shell are achieved.
[0026] (2) In the catalyst prepared by the present invention, glycine, as a nitrogen source and carbon source, has excellent electron transfer ability, providing a large number of catalytic active sites for hydrogenation reaction, thereby improving catalytic efficiency.
[0027] (3) In the process of preparing the catalyst, the present invention adopts a simple and controllable hydrothermal method, and controls the reaction conditions (such as temperature and time) to regulate and improve the morphology, chemical composition and geometric structure of the catalyst, and synthesizes a glycine-derived nitrogen-doped carbon-coated platinum catalyst with a certain particle size distribution and specific morphology.
[0028] (4) In this invention, the glycine-derived nitrogen-doped carbon coating can prevent the migration and aggregation of Pt particles during high-temperature or long-term reactions, thereby effectively inhibiting Pt sintering. At the same time, in acidic environments, the Pt dissolution is reduced by blocking corrosive media, which greatly enhances catalytic stability.
[0029] (5) The catalyst prepared by this invention does not contain any other transition metal elements except for the active component of platinum metal, which reduces the difficulty of recycling precious metal catalysts. (iv) Description of the attached drawings
[0030] Figure 1 This is a transmission electron microscope (TEM) image of the glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Example 5. (V) Detailed Implementation
[0031] The technical solution of the present invention will be described below with specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0032] 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.
[0033] Unless otherwise specified, the operating procedures in the embodiments and comparative examples of this invention are all performed at room temperature. Room temperature refers to 20–25°C.
[0034] Example 1
[0035] 1.0 g of glycine was dissolved in 50 mL of water and stirred continuously at room temperature for 1 h. 3 g of commercially available 1 wt% Pt / C (T1H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixed solution and stirred at 400 rpm for 1 h. The mixture was then continuously sonicated at 40% power for 20 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 100 °C for 10 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 40 °C for 3 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 300 °C for 2 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0036] Example 2
[0037] 2.0 g of glycine was dissolved in 60 mL of water and stirred continuously at room temperature for 2 h. 3 g of commercially available 2 wt% Pt / C (T2H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixed solution and stirred at 400 rpm for 2 h. The mixture was then continuously sonicated at 40% power for 30 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 110 °C for 12 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 50 °C for 4 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 400 °C for 3 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0038] Example 3
[0039] 3.0 g of glycine was dissolved in 70 mL of water and stirred continuously at room temperature for 3 h. 3 g of commercial 3wt% Pt / C (T3H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixed solution and stirred at 400 rpm for 3 h, followed by continuous sonication at 40% power for 40 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 120 °C for 14 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 60 °C for 5 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 500 °C for 3 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0040] Example 4
[0041] 4.0 g of glycine was dissolved in 80 mL of water and stirred continuously at room temperature for 3 h. 3 g of commercially available 4 wt% Pt / C (T4H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixed solution and stirred at 500 rpm for 4 h. The mixture was then continuously sonicated at 50% power for 50 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 130 °C for 16 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 70 °C for 6 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 600 °C for 3 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0042] Example 5
[0043] 5.0 g of glycine was dissolved in 80 mL of water and stirred continuously at room temperature for 3 h. 3 g of commercially available 5 wt% Pt / C (T5H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixed solution and stirred at 500 rpm for 5 h. The mixture was then continuously sonicated at 50% power for 50 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 140 °C for 18 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 80 °C for 6 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 700 °C for 3 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0044] Example 6
[0045] 6.0 g of glycine was dissolved in 80 mL of water and stirred continuously at room temperature for 3 h. 3 g of commercially available 5 wt% Pt / C (T5H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixed solution and stirred at 500 rpm for 5 h. The mixture was then continuously sonicated at 50% power for 50 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 150 °C for 20 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 90 °C for 6 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 800 °C for 3 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0046] Example 7
[0047] 150g of distilled water, 10g of 98wt% concentrated sulfuric acid, 20g of nitrobenzene, 0.2g of hexadecyltrimethylammonium chloride, and 0.5g of the glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Example 1 were added to an acid-resistant high-pressure reactor. The reactor was then closed, and the air inside the reactor was replaced three times with nitrogen and then three times with hydrogen. The temperature was raised to 60°C and the hydrogen pressure was 0.6MPa. Stirring was started at a speed of 1000 r / min and the reaction was carried out for 80 min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 100wt%, and the selectivity for p-aminophenol was 81.9wt%.
[0048] Example 8
[0049] 170g of distilled water, 15g of 98wt% concentrated sulfuric acid, 30g of nitrobenzene, 0.3g of hexadecyltrimethylammonium chloride, and 0.6g of the glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Example 2 were added to an acid-resistant high-pressure reactor. The reactor was then closed, and the air inside the reactor was replaced three times with nitrogen and then three times with hydrogen. The temperature was raised to 70°C and the hydrogen pressure was 0.8MPa. Stirring was started at a speed of 1000 r / min and the reaction was carried out for 80 min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 100wt%, and the selectivity of p-aminophenol was 82.2wt%.
[0050] Example 9
[0051] 190g of distilled water, 20g of 98wt% concentrated sulfuric acid, 40g of nitrobenzene, 0.4g of hexadecyltrimethylammonium chloride, and 0.7g of glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Example 3 were added to an acid-resistant high-pressure reactor. The reactor was then closed, and the air inside the reactor was replaced three times with nitrogen and then three times with hydrogen. The temperature was raised to 80°C and the hydrogen pressure was 1.0MPa. Stirring was started at a speed of 1000r / min and the reaction was carried out for 80min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 100wt%, and the selectivity for p-aminophenol was 83.6wt%.
[0052] Example 10
[0053] 210g of distilled water, 25g of 98wt% concentrated sulfuric acid, 50g of nitrobenzene, 0.5g of hexadecyltrimethylammonium chloride, and 0.8g of the glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Example 4 were added to an acid-resistant high-pressure reactor. The reactor was then closed, and the air inside the reactor was replaced three times with nitrogen and then three times with hydrogen. The temperature was raised to 90°C and the hydrogen pressure was 1.2MPa. Stirring was started at a speed of 1000r / min and the reaction was carried out for 80min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 100wt%, and the selectivity for p-aminophenol was 85.3wt%.
[0054] Example 11
[0055] 230g distilled water, 30g 98wt% concentrated sulfuric acid, 60g nitrobenzene, 0.6g hexadecyltrimethylammonium chloride, and 0.9g glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Example 5 were added to an acid-resistant high-pressure reactor. The reactor was then closed, and the air inside the reactor was replaced three times with nitrogen and then three times with hydrogen. The temperature was raised to 100℃ and the hydrogen pressure was 1.4MPa. Stirring was started at a speed of 1000r / min and the reaction was carried out for 80min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 100wt%, and the selectivity of p-aminophenol was 85.9wt%.
[0056] Example 12
[0057] In an acid-resistant high-pressure reactor, 250 g of distilled water, 35 g of 98 wt% concentrated sulfuric acid, 60 g of nitrobenzene, 0.6 g of hexadecyltrimethylammonium chloride, and 0.5 g of the glycine-derived carbon-coated platinum catalyst prepared in Example 6 were added. The reactor was then closed, and the air inside was replaced with nitrogen four times, followed by hydrogen three times. The temperature was raised to 80 °C and the hydrogen pressure to 1.2 MPa. Stirring was started at a rate of 1000 r / min, and the reaction was carried out for 80 min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, and the catalyst was recovered by filtration. The filtrate was analyzed by liquid chromatography, showing a nitrobenzene conversion of 100 wt% and a p-aminophenol selectivity of 86.8 wt%. The recovered catalyst was reused in experiments under the same conditions, and the results are shown in Table 1.
[0058] Table 1. Application results of the catalyst prepared in Example 12
[0059]
[0060] Comparative Example 1
[0061] 1.0 g of glucose was dissolved in 50 mL of water and stirred continuously at room temperature for 1 h. 3 g of commercially available 1 wt% Pt / C (T1H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixture and stirred at 550 rpm for 1 h, followed by continuous sonication at 60% power for 20 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 100 °C for 10 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 40 °C for 3 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 300 °C for 2 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0062] 190g of distilled water, 20g of 98wt% concentrated sulfuric acid, 40g of nitrobenzene, 0.4g of hexadecyltrimethylammonium chloride, and 0.7g of glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Comparative Example 1 were added to an acid-resistant high-pressure reactor. The reactor was then closed, and the air inside was replaced three times with nitrogen and then three times with hydrogen. The temperature was raised to 80℃ and the hydrogen pressure was 1.0MPa. Stirring was started at a speed of 1000r / min and the reaction was carried out for 80min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 88.7wt%, and the selectivity for p-aminophenol was 76.4wt%.
[0063] Comparative Example 2
[0064] 2.0 g of glucose was dissolved in 60 mL of water and stirred continuously at room temperature for 2 h. 3 g of commercial 2 wt% Pt / C (T2H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixed solution and stirred at 550 rpm for 2 h, followed by continuous sonication at 60% power for 30 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 110 °C for 12 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 50 °C for 4 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 400 °C for 3 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0065] 190g distilled water, 20g 98wt% concentrated sulfuric acid, 40g nitrobenzene, 0.4g hexadecyltrimethylammonium chloride, and 0.7g glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Comparative Example 2 were added to an acid-resistant high-pressure reactor. The reactor was then closed, and the air inside the reactor was replaced three times with nitrogen and then three times with hydrogen. The temperature was raised to 80℃ and the hydrogen pressure was 1.0MPa. Stirring was started at a speed of 1000r / min, and the reaction was carried out for 80min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, and the catalyst was recovered by filtration. The filtrate was analyzed by high-performance liquid chromatography, and the conversion rate of nitrobenzene was 87.5wt%, and the selectivity for p-aminophenol was 76.1wt%.
[0066] Comparative Example 3
[0067] 3.0 g of glucose was dissolved in 70 mL of water and stirred continuously at room temperature for 3 h. 3 g of commercial 3wt% Pt / C (T3H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixed solution and stirred at 550 rpm for 3 h, followed by continuous sonication at 60% power for 40 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 120 °C for 14 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 60 °C for 5 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 500 °C for 3 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0068] 190g distilled water, 20g 98wt% concentrated sulfuric acid, 40g nitrobenzene, 0.4g hexadecyltrimethylammonium chloride, and 0.7g glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Comparative Example 3 were added to an acid-resistant high-pressure reactor. The reactor was then closed, and the air inside was replaced with nitrogen three times, followed by hydrogen three times. The temperature was raised to 80℃ and the hydrogen pressure was 1.0MPa. Stirring was started at a speed of 1000r / min, and the reaction was carried out for 80min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, and the catalyst was recovered by filtration. The filtrate was analyzed by high-performance liquid chromatography, and the conversion rate of nitrobenzene was 85.5wt%, and the selectivity for p-aminophenol was 75.2wt%.
[0069] Comparative Example 4
[0070] 4.0 g of glucose was dissolved in 80 mL of water and stirred continuously at room temperature for 3 h. 3 g of commercially available 4 wt% Pt / C (T4H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixture and stirred at 600 rpm for 4 h, followed by continuous sonication at 70% power for 50 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 130 °C for 16 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 70 °C for 6 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 600 °C for 3 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0071] 190g of distilled water, 20g of 98wt% concentrated sulfuric acid, 40g of nitrobenzene, 0.4g of hexadecyltrimethylammonium chloride, and 0.7g of glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Comparative Example 4 were added to an acid-resistant high-pressure reactor. The reactor was then closed, and the air inside was replaced three times with nitrogen and then three times with hydrogen. The temperature was raised to 80℃ and the hydrogen pressure was 1.0MPa. Stirring was started at a speed of 1000r / min and the reaction was carried out for 80min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 85.1wt%, and the selectivity for p-aminophenol was 74.6wt%.
[0072] Comparative Example 5
[0073] 5.0 g of glucose was dissolved in 80 mL of water and stirred continuously at room temperature for 3 h. 3 g of commercial 5 wt% Pt / C (T5H3X-2 type, Shaanxi Ruike New Material Co., Ltd.) was added to the mixed solution and stirred at 600 rpm for 5 h, followed by continuous sonication at 70% power for 50 min to ensure uniform dispersion. The mixture was transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 140 °C for 18 h. After cooling to room temperature, the product was collected by filtration, washed three times with ethanol to remove impurities, and vacuum dried at 80 °C for 6 h to remove moisture. Finally, the dried product was ground into a uniform powder in an agate mortar and calcined at 700 °C for 3 h under a nitrogen atmosphere to obtain a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
[0074] 190 g of distilled water, 20 g of 98 wt% concentrated sulfuric acid, 40 g of nitrobenzene, 0.4 g of hexadecyltrimethylammonium chloride, and 0.7 g of glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared in Comparative Example 5 were added to an acid-resistant high-pressure reactor. The reactor was closed, and the air inside was replaced three times with nitrogen, followed by three times with hydrogen. The temperature was raised to 80 °C and the hydrogen pressure was 1.0 MPa. Stirring was started at a rate of 1000 r / min, and the reaction was carried out for 80 min. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, and the catalyst was recovered by filtration. The filtrate was analyzed by high-performance liquid chromatography, and the conversion rate of nitrobenzene was 84.9 wt%, and the selectivity for p-aminophenol was 74.8 wt%. The recovered catalyst was reused in experiments under the same reaction conditions, and the results are shown in Table 2.
[0075] Table 2 shows the application results of catalyst preparation in Comparative Example 5.
[0076]
Claims
1. A method for preparing a glycine-derived nitrogen-doped carbon-coated platinum catalyst, characterized by: The preparation method is carried out according to the following steps: (1) taking a supported platinum catalyst, the supported platinum catalyst comprising a carrier and a metal active component supported on the carrier, the metal active component being Pt, adding it into a uniform aqueous glycine solution to make it uniformly dispersed; (2) transferring the mixture obtained in step (1) into a reaction kettle to carry out hydrothermal reaction, the hydrothermal reaction temperature being 100-150 DEG C, the hydrothermal reaction time being 10-20 h; (3) cooling the mixture obtained in step (2) to room temperature, collecting the product by suction filtration, washing it with ethanol sufficiently, and then carrying out vacuum drying; (4) grinding the dried product obtained in step (3) into a uniform powder, and then calcining it at a high temperature of 300-800 DEG C under an inert protective atmosphere for 2-10 h to prepare a glycine-derived nitrogen-doped carbon-coated platinum catalyst.
2. The production method according to claim 1, characterized by: In step (1), the feeding ratio of the supported metal platinum catalyst to the aqueous glycine solution is calculated in the following manner: the feeding ratio of the supported metal platinum catalyst to water is 3 g: 50-80 mL, and the mass ratio of the supported platinum catalyst to glycine is 1: (0.3-2), preferably 1:1.5-2, and most preferably 1:
2.
3. The production method according to claim 1, wherein: In step (1), the carrier of the supported platinum catalyst is activated carbon, SiO2 or TiO2, and the loading amount of platinum with respect to the carrier is 1-5 wt%.
4. The production method according to claim 1, wherein: In step (2), the hydrothermal reaction temperature is 100-150 DEG C, preferably 140-150 DEG C, and more preferably 150 DEG C; and the hydrothermal reaction time is 10-20 h, preferably 18-20 h, and more preferably 20 h.
5. The production method according to claim 1, wherein: In step (4), the inert protective atmosphere is one or more of nitrogen, argon and helium, the calcination temperature is 300-800 DEG C, preferably 700-800 DEG C, and more preferably 800 DEG C; and the calcination time is 2-10 h, preferably 2-3 h, and more preferably 3 h.
6. A glycine-derived nitrogen-doped carbon-coated platinum catalyst prepared by the preparation method according to any one of claims 1-5.
7. Use of the glycine-derived nitrogen-doped carbon-coated platinum catalyst according to claim 6 in the rearrangement hydrogenation of nitrobenzene to prepare p-aminophenol.
8. Use according to claim 7, wherein: The specific method of the use is as follows: adding distilled water, 98 wt% concentrated sulfuric acid, nitrobenzene, a surfactant and the glycine-derived nitrogen-doped carbon-coated platinum catalyst in an acid-resistant high-pressure reaction kettle, the mass ratio being 150-250: 10-50: 20-100: 0.2-0.8: 0.5-3, introducing hydrogen, and carrying out the rearrangement hydrogenation reaction under stirring to obtain the target product p-aminophenol.
9. Use according to claim 8, wherein: The surfactant is cetyltrimethylammonium chloride.
10. Use according to claim 8 or 9, characterized in that: The reaction temperature of the rearrangement hydrogenation reaction is 60-100 DEG C, and the hydrogen pressure in the reaction kettle is 0.6-1.5 MPa.