Nitrogen-doped activated carbon loaded noble metal catalyst as well as preparation method and application thereof

Abstract

The invention discloses a nitrogen-doped activated carbon supported noble metal catalyst and a preparation method and application thereof, and relates to the technical field of supported noble metal catalysts, the catalyst comprises a carrier and a noble metal active component; the carrier is nitrogen-doped activated carbon; the noble metal active component is platinum or palladium; and the loading capacity of the noble metal active component is not higher than 5wt% of the weight of the carrier, preferably 1-3wt%. The catalyst provided by the invention has the characteristics of high catalyst activity and selectivity and simple preparation process, and has industrial application performance.

Description

Technical Field

[0001] The present invention relates to the technical field of loaded precious metal catalysts, and more particularly to a nitrogen-doped activated carbon loaded precious metal catalyst and a preparation method and application thereof. Background Art

[0002] p-Aminophenol (also known as p-hydroxyaniline) is an important organic intermediate, widely used in the fields of medicine, dyes, antioxidants, rubber and photosensitive materials. As early as 1874, p-aminophenol was prepared by reducing p-nitrophenol with iron powder. With the increase in demand for p-aminophenol and the improvement of environmental protection requirements, new methods and routes for synthesizing p-aminophenol in one step using nitrobenzene as raw material have become a research hotspot in recent years. The one-step synthesis process has the advantages of easy raw materials, simple process and low cost. The main reaction process is that nitrobenzene is hydrogenated to generate phenylhydroxylamine, and p-aminophenol is obtained after Bamberger rearrangement. Among them, the method of synthesizing p-aminophenol in one step by direct catalyst hydrogenation of nitrobenzene has low cost, high yield, less three wastes, and has good economic and social benefits. At present, the process generally uses loaded Pt or Pd as a catalyst and reacts in a dilute acid medium. The raw materials of this method are cheap and easy to obtain, the production cost is low, the process is few, and the pollution is small. Pt and Pd are used as the active components of the catalyst, activated carbon is used as the carrier, and appropriate surfactants are added to react at 70-110°C and 0.1-1MPa.

[0003] The p-aminophenol synthesis method disclosed in US Pat. No. 4,885,389 and US Pat. No. 4,264,529 uses Pt / C or Pt / alumina, wherein the Pt / alumina catalyst is easily dissolved in the presence of an acidic medium, resulting in serious catalyst loss, which causes the catalyst activity to drop quickly. The p-aminophenol synthesis method disclosed in Chinese patent CN1075489C uses a Pt / nylon catalyst, which has good catalyst stability, but has the defect of poor selectivity of p-aminophenol (PAP). The Pt / C catalyst disclosed in US Pat. No. 4,571,437 adds sulfides such as ethyl sulfide and dimethyl sulfoxide during use, which improves the selectivity of the catalyst, but reduces the activity and service life of the catalyst. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a nitrogen-doped activated carbon-supported noble metal catalyst and its preparation method and application. The catalyst of the present invention has the characteristics of high catalyst activity and selectivity, simple preparation process, and industrial application performance.

[0005] One of the purposes of the present invention is to provide a nitrogen-doped activated carbon-supported noble metal catalyst.

[0006] The nitrogen-doped activated carbon-supported noble metal catalyst of the present invention comprises a carrier and a noble metal active component;

[0007] The carrier is nitrogen-doped activated carbon;

[0008] The noble metal active component is platinum or palladium;

[0009] The loading amount of the noble metal active component is not higher than 5 wt % of the carrier mass, preferably 1 to 3 wt %.

[0010] A second object of the present invention is to provide a method for preparing a nitrogen-doped activated carbon-supported noble metal catalyst.

[0011] The method for preparing the nitrogen-doped activated carbon-supported noble metal catalyst of the present invention comprises:

[0012] The activated carbon after activation treatment is added to a nitrogen source solution to prepare nitrogen-doped activated carbon, which is then mixed with a reducing agent solution and a precipitant solution, and then a noble metal precursor solution is added dropwise, and the catalyst is obtained after filtering and drying.

[0013] Preferably, the method comprises:

[0014] (1) After the activated carbon is soaked and boiled in an acidic solution, it is filtered and washed with hot water until the pH value is neutral, and then dried to obtain activated activated carbon;

[0015] (2) dissolving a nitrogen source in deionized water to obtain a nitrogen source solution;

[0016] (3) adding the activated carbon to the nitrogen source solution to obtain a nitrogen-containing activated carbon slurry;

[0017] (4) filtering and drying the nitrogen-containing activated carbon slurry, and then calcining it under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0018] (5) Under stirring, the nitrogen-doped activated carbon, reducing agent solution and precipitant solution are mixed, and then the noble metal precursor solution is added dropwise, followed by constant temperature, filtering and drying to obtain the catalyst.

[0019] Preferably,

[0020] In step (1):

[0021] The acidic solution is a nitric acid solution or a hydrochloric acid solution. Preferably, the concentration of the acidic solution is 15-25 wt %; and / or,

[0022] The feed ratio of the acid solution to the activated carbon is 5 to 15 mL / g, preferably 8 to 12 mL / g; and / or,

[0023] The soaking and boiling time is 1 to 4 hours; and / or,

[0024] The hot water temperature is 60-90°C; and / or,

[0025] The drying temperature is 110-150°C.

[0026] Preferably,

[0027] In step (2):

[0028] The nitrogen source is acrylamide or benzamide; and / or,

[0029] The concentration of the nitrogen source after being dissolved in deionized water is 5 to 15 wt %; and / or,

[0030] The temperature of the deionized water is 25-90°C.

[0031] Preferably,

[0032] In step (3):

[0033] The mass ratio of the nitrogen source to the activated carbon is (0.1-10):1, preferably (1-3):1; and / or,

[0034] The beating temperature is 25-90° C., and / or the beating time is 1 to 24 hours.

[0035] Preferably,

[0036] In step (4):

[0037] The drying temperature is 110-150° C.; and / or,

[0038] The calcination temperature is 500-800° C., preferably 550-750° C., and / or the calcination time is 2-8 hours, preferably 3-5 hours.

[0039] Preferably,

[0040] In step (5):

[0041] The stirring speed is 10-500 rpm, and / or the stirring temperature is 50-95° C.; and / or,

[0042] The reducing agent is formaldehyde or ethylene glycol; and / or,

[0043] The precipitant is at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide; and / or,

[0044] The solvent of the reducing agent solution is a commonly used solvent in the art, such as deionized water; and / or,

[0045] The solvent of the precipitant solution is a commonly used solvent in the art, such as deionized water; and / or,

[0046] The concentration of the reducing agent solution is 0.5-5wt%; and / or,

[0047] The concentration of the precipitant solution is 10-40 wt %; and / or,

[0048] The noble metal precursor solution is a soluble acid salt solution of a noble metal active component, preferably a chlorate solution or a nitrate solution of a noble metal active component, more preferably at least one of a chloroplatinic acid solution, a palladium nitrate solution, and a palladium chloride solution; and / or,

[0049] The solvent of the noble metal precursor solution is a commonly used solvent in the art, such as deionized water; and / or,

[0050] The concentration of the noble metal precursor solution is 0.1-10wt%; and / or,

[0051] The mass ratio of the reducing agent, the precipitating agent and the precious metal active component is (0.5-6): (2-10): 1, preferably (1-3): (3-8): 1; and / or,

[0052] The dropping time of the chloroplatinic acid solution is 0.1-2 hours; and / or,

[0053] The constant temperature is 50-95° C., and / or the constant temperature time is 0.5-3 hours; and / or,

[0054] The drying temperature is 110-150°C.

[0055] The specific preparation steps are as follows:

[0056] (1) soaking the activated carbon in a 15-25.0 wt% acid solution and boiling it for 1-4 h, then filtering and washing it with 60-90° C. hot water for multiple times until the pH value is neutral, and then drying it at 110-150° C. to obtain activated activated carbon;

[0057] (2) dissolving a nitrogen source in deionized water at 25-90° C. and stirring until the mixture is uniformly mixed to obtain a nitrogen source solution;

[0058] (3) under stirring, adding the activated carbon prepared in step (1) to the nitrogen source solution prepared in step (2) so that the mass ratio of the nitrogen source to the activated carbon in the nitrogen source solution is (0.5-10):1, and beating at 25-90° C. for 1-24 hours to obtain a nitrogen-containing activated carbon slurry;

[0059] (4) filtering the nitrogen-containing activated carbon slurry prepared in step (3), drying at 110-150° C. for 5-20 hours, and then calcining at 500-800° C. for 2-8 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0060] (5) Under stirring conditions at 50-95° C. and 10-500 rpm, the nitrogen-doped activated carbon, reducing agent solution and precipitant solution prepared in step (4) are mixed, and then the noble metal precursor solution is added dropwise, followed by constant temperature, filtering and drying to obtain the catalyst.

[0061] The third object of the present invention is to provide an application of a nitrogen-doped activated carbon-supported noble metal catalyst in the catalytic hydrogenation of nitrobenzene to synthesize p-aminophenol.

[0062] Preferably,

[0063] The reaction conditions for synthesizing p-aminophenol by catalytic hydrogenation of nitrobenzene are:

[0064] The catalyst, nitrobenzene, dilute sulfuric acid and surfactant are reacted at a temperature of 70 to 110°C and a hydrogen pressure of 0.1 to 1 MPa for 1 to 6 hours, and then separated and post-processed to obtain the product p-aminophenol;

[0065] Preferably, the hydrogen pressure is 0.2-6.0 MPa.

[0066] The specific application methods are as follows:

[0067] Put the catalyst, nitrobenzene, dilute sulfuric acid and surfactant into a high-pressure hydrogenation reactor, seal the reactor, replace the air with hydrogen and start stirring, react for 1-6 hours at a temperature of 70-110° C. and a hydrogen pressure of 0.1-1 MPa (preferably 0.2-6.0 MPa), stop the reaction, take samples for analysis, and separate and treat the hydrogenated liquid to obtain the product p-aminophenol.

[0068] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0069] The present invention prepares a catalyst for synthesizing p-aminophenol from nitrobenzene. The particle size of the active component of the catalyst of the present invention is small, and the catalyst preparation process includes the steps of activated carbon nitrogen doping, precipitation reduction of the noble metal active component, filtering, drying and the like. The prepared catalyst is particularly suitable for synthesizing p-aminophenol from nitrobenzene by hydrogenation, and has the characteristics of high catalytic activity and selectivity in the one-step synthesis of p-aminophenol from nitrobenzene. The conversion rate of nitrobenzene can reach more than 90%, and the selectivity of p-aminophenol can also reach more than 90%.

[0070] In the process of loading the noble metal active component, the present invention uses a precipitant and a reducing agent to precipitate and reduce the noble metal active component. The prepared catalyst is particularly suitable for use as a catalyst in the one-step synthesis of p-aminophenol from nitrobenzene, and can effectively improve the nitrobenzene conversion rate and the selectivity of p-aminophenol. This is because: the present invention adds the precipitant and the reducing agent at the same time, and then drops the noble metal precursor solution, and uses a nitrogen source to load the noble metal active component on the activated carbon modified carrier. On the one hand, the introduction of the nitrogen source enriches the nitrogen-containing functional groups on the catalyst surface, which is beneficial to the dispersion of the noble metal active component on the activated carbon carrier; on the other hand, the use of the precipitant can make the noble metal active component precipitate and load on the activated carbon in the form of oxides, and the noble metal active component is "anchored" on the activated carbon carrier, which further improves the dispersion of the noble metal active component. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 is the N1s binding energy of the catalyst prepared in Example 1;

[0072] Depend on Figure 1 It can be seen that according to the X-ray photoelectron spectrum of nitrogen in nitrogen-containing functional groups in activated carbon studied in the literature RJJJansen and H.Van Berkkum, XPS of Nitrogen-containing Functional Groups on Activated Carbon, Carbon, (1995) Vol.33No.8:1021-1027, the peak of N1s binding energy 401.0-401.4ev corresponds to pyrrole nitrogen, the peak of 399.7-399.9ev corresponds to amide, lactam, imide nitrogen, and the peak of 398.7ev corresponds to pyridine nitrogen, indicating that the catalyst surface after nitrogen modification contains different types of nitrogen elements;

[0073] Figure 2 The XRD patterns of the catalysts prepared in Example 1 and Comparative Example 1 are shown in FIG.

[0074] Depend on Figure 2 It can be seen that the intensity of Pt in the catalyst prepared in Example 1 is weak and the half-peak width is wide, indicating that Pt is in a state of fine and highly dispersed particles on the surface of the carrier. According to the Scherrer formula, it can be calculated that the Pt particle sizes of the catalysts in Example 1 and Comparative Example 1 are approximately 3-5 nm and 7-9 nm, respectively.

[0075] Figure 3 TEM image of the catalyst prepared in Example 1;

[0076] Depend on Figure 3 It can be seen that the Pt clusters of the catalyst prepared in Example 1 have a size range of 3-5 nm;

[0077] Figure 4 This is a TEM image of the catalyst prepared in Comparative Example 1;

[0078] Depend on Figure 4 It can be seen that the Pt clusters of the catalyst prepared in Comparative Example 1 have a size range of 10-20 nm. DETAILED DESCRIPTION

[0079] The present invention is described in detail below in conjunction with specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0080] The raw materials used in the examples and comparative examples of the present invention are all commercially available products.

[0081] Example 1

[0082] (1) 50 g of activated carbon (Xilong Science AR) was added to 500 ml of 20 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0083] (2) dissolving 6 g of acrylamide (Xilong Science AR) in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0084] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0085] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0086] (5) Weigh 2.5 g of the above-mentioned nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then add dropwise a solution composed of 10 g of deionized water and 0.2040 g of hexahydrate chloroplatinic acid (Xilong Science AR), the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0087] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0088] Example 2

[0089] (1) 50 g of activated carbon was added to 500 ml of 20 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0090] (2) dissolving 12 g of acrylamide in 70 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0091] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0092] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0093] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0094] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0095] Example 3

[0096] (1) 50 g of activated carbon was added to 500 ml of 20% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0097] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0098] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0099] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0100] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.1014 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 1.5 wt% of the mass of the nitrogen-doped activated carbon.

[0101] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0102] Example 4

[0103] (1) 50 g of activated carbon was added to 500 ml of 20 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0104] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0105] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0106] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0107] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetrapropylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0108] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0109] Example 5

[0110] (1) 50 g of activated carbon was added to 500 ml of 20 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0111] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0112] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0113] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0114] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 12 g of 1 wt% formaldehyde solution and 2.5 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.3040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 4.5 wt% of the mass of the nitrogen-doped activated carbon.

[0115] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0116] Example 6

[0117] (1) 50 g of activated carbon was added to 500 ml of 20 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0118] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0119] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0120] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0121] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 12 g of 1 wt% formaldehyde solution and 2.5 g of 25% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.3040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 4.5 wt% of the mass of the nitrogen-doped activated carbon.

[0122] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0123] Example 7

[0124] (1) 50 g of activated carbon was added to 400 ml of 15 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0125] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0126] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0127] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0128] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0129] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0130] Example 8

[0131] (1) 50 g of activated carbon was added to 750 ml of 25 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0132] (2) dissolving 2 g of acrylamide in 35 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0133] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0134] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0135] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0136] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0137] Example 9

[0138] (1) 50 g of activated carbon was added to 500 ml of 20 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0139] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0140] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0141] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0142] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 12 g of 0.5 wt% formaldehyde solution and 2 g of 35 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0143] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0144] Example 10

[0145] (1) 50 g of activated carbon was added to 500 ml of 20 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0146] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0147] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0148] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0149] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 3 wt% formaldehyde solution and 1.55 g of 12 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0150] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0151] Embodiment 11

[0152] (1) 50 g of activated carbon was added to 500 ml of 20 wt% hydrochloric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0153] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0154] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0155] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0156] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0157] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0158] Example 12

[0159] (1) 50 g of activated carbon was added to 500 ml of 20 wt% hydrochloric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0160] (2) dissolving 6 g of benzamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0161] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0162] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0163] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0164] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0165] Example 13

[0166] (1) 50 g of activated carbon was added to 500 ml of 20 wt% hydrochloric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0167] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0168] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0169] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0170] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% ethylene glycol solution and 1.55 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0171] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0172] Embodiment 14

[0173] (1) 50 g of activated carbon was added to 500 ml of 20 wt% hydrochloric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0174] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0175] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0176] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0177] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetraethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0178] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0179] Embodiment 15

[0180] (1) 50 g of activated carbon was added to 500 ml of 20 wt% hydrochloric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0181] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0182] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0183] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0184] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetrapropylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0185] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0186] Example 16

[0187] (1) 50 g of activated carbon was added to 500 ml of 20 wt% hydrochloric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0188] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0189] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0190] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0191] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir evenly at a stirring speed of 300 rpm, then dropwise add a solution composed of 10 g of deionized water and 0.188 g of palladium nitrate dihydrate, the addition time is 0.5 hour, then keep the temperature constant for 1 hour, filter, and dry at 110°C to obtain the desired catalyst, wherein the palladium loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0192] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0193] Embodiment 17

[0194] (1) 50 g of activated carbon was added to 500 ml of 20 wt% hydrochloric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0195] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0196] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0197] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0198] (5) Weigh 2.5 g of the above nitrogen-doped activated carbon, add 15 g of 1 wt% formaldehyde solution and 1.55 g of 25 wt% tetramethylammonium hydroxide solution, heat to 95°C, stir at 300 rpm, then dropwise add a solution of 10 g of deionized water and 0.125 g of palladium chloride for 0.5 h, then keep the temperature constant for 1 h, filter, and dry at 110°C to obtain the desired catalyst, wherein the palladium loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0199] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0200] Comparative Example 1

[0201] (1) 50 g of activated carbon was added to 300 ml of 20 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0202] (2) Weigh 2.5 g of the above-mentioned activated carbon, add 20 g of 1 wt% formaldehyde solution; heat to 95°C, stir at 300 rpm, then add 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate for 0.5 h, keep constant temperature for 1 h, filter, and dry at 110°C to obtain the desired catalyst, in which the platinum loading is 3 wt% of the mass of the activated carbon.

[0203] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0204] Comparative Example 2

[0205] (1) 50 g of activated carbon was added to 500 ml of 20 wt% nitric acid solution, refluxed and stirred for 3 hours, filtered and washed with 80° C. hot water until the pH value was neutral, and then dried at 120° C. for 24 hours to obtain activated activated carbon;

[0206] (2) dissolving 6 g of acrylamide in 50 g of deionized water at 60° C. to obtain a nitrogen source solution;

[0207] (3) Weighing 4 g of the activated carbon and adding it to the nitrogen source solution, and then stirring at 70° C. for 10 hours to obtain a nitrogen-containing activated carbon slurry;

[0208] (4) filtering the nitrogen-containing activated carbon slurry, drying it at 110° C. for 12 hours, and then calcining it at 650° C. for 4 hours under nitrogen conditions to obtain nitrogen-doped activated carbon;

[0209] (5) Weigh 2.5 g of the nitrogen-doped activated carbon, add 15 g of 1% formaldehyde solution, heat to 95°C, stir evenly at 300 rpm, then dropwise add a solution consisting of 10 g of deionized water and 0.2040 g of chloroplatinic acid hexahydrate for 0.5 h, then keep the temperature constant for 1 h, filter, and dry at 110°C to obtain the desired catalyst, in which the platinum loading is 3 wt% of the mass of the nitrogen-doped activated carbon.

[0210] The catalyst was used in the reaction of synthesizing p-aminophenol from nitrobenzene, and the catalyst performance of the catalyst was evaluated. Evaluation method: 20 grams of nitrobenzene, 100 ml of 15wt% dilute sulfuric acid, 0.15 grams of catalyst, and 0.2 grams of hexadecyltrimethylammonium bromide were put into a high-pressure hydrogenation reactor, the reactor was sealed, the air was replaced with hydrogen, and stirring was started. Under the conditions of a temperature of 85°C and a hydrogen pressure of 0.5 MPa, the reaction was carried out for 2 hours and a sample was taken. The reaction liquid was analyzed by liquid chromatography. The results are shown in Table 1.

[0211] Table 1

[0212] catalyst Nitrobenzene conversion rate % p-Aminophenol selectivity% Example 1 91.5 91.3 Example 2 90.8 92.3 Example 3 88.5 93.1 Example 4 89.3 91.0 Example 5 88.5 90.0 Example 6 92.4 88.5 Example 7 89.3 90.9 Example 8 87.3 86.5 Example 9 89.5 87.6 Example 10 87.5 90.11 Embodiment 11 91.1 90.8 Example 12 85.6 87.8 Example 13 82.3 83.7 Embodiment 14 83.6 81.5 Embodiment 15 80.9 82.0 Example 16 89.3 83.6 Embodiment 17 88.7 81.8 Comparative Example 1 80.3 80.6 Comparative Example 2 82.4 79.4

[0213] It can be seen from Table 1 that the catalyst of the present invention has higher activity and selectivity than the activated carbon not doped with nitrogen in Comparative Example 1; the catalyst of the present invention also has higher activity and selectivity than the catalyst of Comparative Example 2 to which no precipitant is added.

Claims

1. A nitrogen-doped activated carbon-supported noble metal catalyst, characterized in that The catalyst comprises a carrier and a noble metal active component; The carrier is nitrogen-doped activated carbon; The noble metal active component is platinum or palladium; The loading amount of the noble metal active component is not higher than 5 wt % of the carrier weight, preferably 1 to 3 wt %.

2. A method for preparing a nitrogen-doped activated carbon-supported noble metal catalyst as claimed in claim 1, characterized in that The method comprises: The activated carbon after activation treatment is added to a nitrogen source solution to prepare nitrogen-doped activated carbon, which is then mixed with a reducing agent solution and a precipitant solution, and then a noble metal precursor solution is added dropwise, and the catalyst is obtained after filtering and drying.

3. The method for preparing a nitrogen-doped activated carbon-supported noble metal catalyst according to claim 2, characterized in that The method comprises: (1) After the activated carbon is soaked and boiled in an acidic solution, it is filtered and washed with hot water until the pH value is neutral, and then dried to obtain activated activated carbon; (2) dissolving a nitrogen source in deionized water to obtain a nitrogen source solution; (3) adding the activated carbon to the nitrogen source solution and slurrying to obtain a nitrogen-containing activated carbon slurry; (4) filtering and drying the nitrogen-containing activated carbon slurry, and then calcining it under nitrogen conditions to obtain nitrogen-doped activated carbon; (5) Under stirring, the nitrogen-doped activated carbon, reducing agent solution and precipitant solution are mixed, and then the noble metal precursor solution is added dropwise, followed by constant temperature, filtering and drying to obtain the catalyst.

4. The method for preparing a nitrogen-doped activated carbon-supported noble metal catalyst according to claim 3, characterized in that: In step (1): The acidic solution is a nitric acid solution or a hydrochloric acid solution; preferably, the concentration of the acidic solution is 15-25wt%; and / or, The feed ratio of the acid solution to the activated carbon is 5 to 15 mL / g, preferably 8 to 12 mL / g; and / or, The soaking and boiling time is 1 to 4 hours; and / or, The hot water temperature is 60-90°C; and / or, The drying temperature is 110-150°C.

5. The method for preparing a nitrogen-doped activated carbon-supported noble metal catalyst according to claim 3, characterized in that: In step (2): The nitrogen source is acrylamide or benzamide; and / or, The concentration of the nitrogen source after being dissolved in deionized water is 5 to 15 wt %; and / or, The temperature of the deionized water is 25-90°C.

6. The method for preparing a nitrogen-doped activated carbon-supported noble metal catalyst according to claim 3, characterized in that: In step (3): The mass ratio of the nitrogen source to the activated carbon is (0.1-10):1, preferably (1-3):1; and / or, The beating temperature is 25-90° C., and / or the beating time is 1 to 24 hours.

7. The method for preparing a nitrogen-doped activated carbon-supported noble metal catalyst according to claim 3, characterized in that: In step (4): The drying temperature is 110-150° C.; and / or, The calcination temperature is 500-800° C., preferably 550-750° C., and / or the calcination time is 2-8 hours, preferably 3-5 hours.

8. The method for preparing a nitrogen-doped activated carbon-supported noble metal catalyst according to claim 3, characterized in that: In step (5): The stirring speed is 10-500 rpm, and / or the stirring temperature is 50-95° C.; and / or, The reducing agent is formaldehyde or ethylene glycol; and / or, The precipitant is at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide; and / or, The concentration of the reducing agent solution is 0.5-5wt%; and / or, The concentration of the precipitant solution is 10-40 wt %; and / or, The noble metal precursor solution is a soluble acid salt solution of a noble metal active component, preferably a chlorate solution or a nitrate solution of a noble metal active component, more preferably at least one of a chloroplatinic acid solution, a palladium nitrate solution, and a palladium chloride solution; and / or, The concentration of the noble metal precursor solution is 0.1-10wt%; and / or, The mass ratio of the reducing agent, the precipitating agent and the precious metal active component is (0.5-6): (2-10): 1, preferably (1-3): (3-8): 1; and / or, The dropping time of the chloroplatinic acid solution is 0.1-2 hours; and / or, The constant temperature is 50-95° C., and / or the constant temperature time is 0.5-3 hours; and / or, The drying temperature is 110-150°C.

9. Use of the catalyst according to claim 1 or the catalyst prepared by the method according to any one of claims 2 to 8 in the reaction of catalytic hydrogenation of nitrobenzene to synthesize p-aminophenol.

10. Use of the catalyst according to claim 9 in the reaction of catalytic hydrogenation of nitrobenzene to synthesize p-aminophenol, characterized in that: The reaction conditions for synthesizing p-aminophenol by catalytic hydrogenation of nitrobenzene are: The catalyst, nitrobenzene, dilute sulfuric acid and surfactant are reacted at a temperature of 70 to 110°C and a hydrogen pressure of 0.1 to 1 MPa for 1 to 6 hours, and then separated and post-processed to obtain the product p-aminophenol; Preferably, the hydrogen pressure is 0.2-6.0 MPa.

Images