Acid-resistant non-noble metal catalyst, preparation method and application thereof
The acid-resistant non-precious metal catalyst prepared by modifying the support and activation steps solves the problems of poor catalyst activity and short lifespan under strong acid conditions, and achieves efficient synthesis of p-aminophenol.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HEFEI UNIV OF TECH
- Filing Date
- 2026-01-27
- Publication Date
- 2026-06-02
AI Technical Summary
Existing catalysts exhibit poor catalytic activity and short lifespan under extreme conditions such as strong acids, making it difficult to meet the needs of industrial applications.
An acid-resistant non-precious metal catalyst is formed by modifying the support and activating the catalyst, including calcination of melamine, sulfuric acid treatment, impregnation of cobalt and nickel salts, and calcination activation.
The prepared catalyst exhibits high activity and stability under strong acid conditions, which improves the selectivity and production efficiency of p-aminophenol and reduces production costs.
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Figure CN122124818A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of acid-resistant metal catalysis, in particular to an acid-resistant non-noble metal catalyst and a preparation method and application thereof. BACKGROUND
[0002] P-aminophenol (PAP) is an important intermediate, widely used in medicine (such as paracetamol and acetaminophen), corrosion inhibitor and dye manufacturing. Due to the low economy and high product quality, it is considered as the best route to directly hydrogenate nitrobenzene (NB) to PAP. The reaction involves partial hydrogenation of NB to generate phenylhydroxylamine (PHA), and then in-situ Bamberger rearrangement to generate PAP in an acidic environment. Carbon-supported noble metal catalyst, especially Pt / C, is considered as the best catalyst for this reaction, but its high price and loss of noble metal due to corrosion limit its further application. Therefore, it is necessary to develop a non-noble metal catalyst with acid resistance and realize efficient and high-selectivity synthesis of p-aminophenol.
[0003] In 2016, in view of the above problems, the prior art developed a Ni-based catalyst 6Ni-Si / AC6 supported by activated carbon (AC) treated with sulfuric acid, which showed excellent acid resistance and high activity and selectivity in the reaction of selective synthesis of p-aminophenol from nitrobenzene. However, the preparation process of the catalyst is complex, and it is difficult to synthesize it on a large scale in industry. In addition, a sulfur-modified Pt / C catalyst was prepared by using thiourea as a precursor and using an impregnation method, which was used for selective hydrogenation of nitrobenzene (NB) to prepare p-aminophenol (PAP). Under the optimal conditions, 99.5% conversion and 72.5% selectivity were achieved. However, this sulfur-doping method by introducing toxic sites reduces the adsorption and dissociation capacity of hydrogen on the catalyst. In the same year, Wang Qingtao et al. designed and prepared a bimetallic Pt-Ni catalyst, which effectively improved the product selectivity and catalyst performance stability for the hydrogenation rearrangement of nitrobenzene to prepare p-aminophenol. Although the introduction of the second metal Ni significantly improved the stability of the catalyst, Pt noble metal was still used, and Ni doping led to a decrease in Pt active sites, resulting in a decrease in the amount of dissociated hydrogen.
[0004] Chinese patent application CN110828834A discloses a method for capturing and chelating metal atoms by using the heptazine structure of g-C3N4 to form Fe-Nx and Ni-Nx double active sites, so that the catalyst has both oxygen reduction and oxygen desorption functions. The method is simple and efficient. Iron source and nickel source are mixed with g-C3N4 in one pot, then iron and nickel are tightly chelated in the vacancies of g-C3N4 through hydrothermal reaction, and finally the active sites of iron and nickel are formed through high-temperature carbonization, thereby obtaining a non-noble metal catalyst with both oxygen reduction and oxygen desorption functions. The catalyst has excellent performance under alkaline conditions and good stability. However, the patent does not mention the improvement of the stability of the catalyst under extreme conditions such as strong acid, so further improvement is needed. SUMMARY
[0005] The technical problem to be solved by the present application is how to solve the problems of poor catalytic activity and short service life of existing catalysts under extreme conditions such as strong acid.
[0006] The present application solves the above technical problems by the following technical means:
[0007] The present application provides a preparation method of an acid-resistant non-noble metal catalyst, comprising the following steps: (1) Modification of the carrier: calcine melamine, grind it into powder, add concentrated sulfuric acid, deionized water and ethanol in sequence and stir, filter and wash, and dry to obtain the modified carrier; (2) Activation of the catalyst: dissolve cobalt salt and nickel salt in deionized water to obtain a metal impregnation solution, add the modified carrier obtained in step (1) and mix, calcine and activate to obtain a solid catalyst, add H2SO4 solution and stir to obtain the catalyst.
[0008] Preferably, in step (1), the calcination is carried out at 400-500°C in air atmosphere for 3-4h.
[0009] Preferably, in step (1), the amounts of powder, concentrated sulfuric acid, deionized water and ethanol are in the ratio of 1-3g:5-20mL:5-20mL:15-60mL.
[0010] Preferably, in step (1), the concentration of concentrated sulfuric acid is 98%.
[0011] Grind melamine into solid powder in a magnetic boat, then add concentrated sulfuric acid and stir for 0.1-1h, slowly add deionized water, and when the mixture changes from sticky mud to white transparent solution, add ethanol and stir for 12-18h.
[0012] The chemical stripping of the calcined melamine using sulfuric acid is a key step. The catalyst carrier can be obtained by chemical stripping, and the catalyst for the synthesis of p-aminophenol from nitrobenzene can be obtained after loading metal.
[0013] Preferably, in step (1), the filtering and washing is filtering and washing with deionized water until neutral.
[0014] Preferably, in step (1), the drying conditions are 120-130℃ for 8-24 h.
[0015] Preferably, in step (2), the cobalt salt includes but is not limited to one or more of cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt acetate, cobalt perchlorate, cobalt bromide, cobalt oxalate, cobalt fluoride, cobalt carbonate, cobalt phosphate, cobalt sulfite, hexamine cobalt trichloride, and cobalt hydroxide.
[0016] Preferably, in step (2), the nickel salt includes but is not limited to one or more of nickel chloride, nickel sulfate, nickel nitrate, nickel acetate, nickel perchlorate, nickel bromide, nickel oxalate, nickel fluoride, nickel carbonate, nickel phosphate, nickel sulfite, hexamine nickel trichloride, and hexamine nickel sulfate.
[0017] Preferably, in step (2), the ratio of the amount of cobalt salt, nickel salt, and deionized water is 0.1-2 g:1-2 g:50 mL.
[0018] Preferably, in step (2), the mixing time is 12-36 h.
[0019] Preferably, in step (2), the calcination and activation conditions are: calcination and activation at 400-600℃ for 2-5 h under a hydrogen and argon atmosphere. Specifically, the sample is placed in a tube furnace, and activated at 1-10℃ / min from room temperature to 400-600℃ under a 5% H2 and Ar atmosphere for 2-5 h.
[0020] Preferably, in step (2), the ratio of the amount of solid catalyst to H2SO4 solution is 1-10 g:50-100 mL.
[0021] Preferably, in step (2), the concentration of the H2SO4 solution is 10-25wt%.
[0022] Preferably, in step (2), the stirring time is 12-24 h.
[0023] The application also provides an acid-resistant non-noble metal catalyst prepared by the above preparation method.
[0024] The application provides the use of the acid-resistant non-noble metal catalyst prepared by the above preparation method in the synthesis of p-aminophenol from nitrobenzene.
[0025] Preferably, the application method is: Using the aforementioned acid-resistant non-precious metal catalyst as the catalyst, nitrobenzene, hexadecyltrimethylammonium bromide, and hydrogen as the reactants, and dilute sulfuric acid as the reaction solvent, the reaction was carried out to obtain the target product, p-aminophenol.
[0026] A further preferred application method is as follows: Weigh 0.01-0.04 g of the above-mentioned acid-resistant non-precious metal catalyst, 0.2-1 g of nitrobenzene, 1-10 mg of hexadecyltrimethylammonium bromide, and 5-15 mL of H2SO4 solution into a reaction vessel, and purge with 0.1-5 MPa of hydrogen gas. React at 30-180 °C and 100-1000 r / min for 1-36 h to obtain the target product p-aminophenol.
[0027] Preferably, the H2SO4 solution concentration is 5-25 wt%.
[0028] The beneficial effects of this invention are as follows: 1. The catalyst prepared by this invention has excellent acid resistance and stability. In the selective hydrogenation of nitrobenzene to prepare p-aminophenol, it can exhibit high activity and high selectivity for p-aminophenol under relatively mild reaction conditions, thereby improving production conditions, reducing production costs, and improving product quality.
[0029] 2. This invention provides a method for preparing an acid-resistant non-precious metal catalyst. The catalyst prepared by this method has good activity and long life under extreme conditions such as strong acid, and has high selectivity for p-aminophenol in the hydrogenation of nitrobenzene to p-aminophenol.
[0030] Of course, implementing any product or method of the present invention does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description
[0031] Figure 1 This is a SEM image of the carrier after modification in Example 1 of the present invention; Figure 2 This is a TEM image of the acid-resistant non-precious metal catalyst prepared in Example 1 of the present invention; Figure 3 This is a graph showing the results of recycling the catalyst prepared in Example 1 of the present invention. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical terms used below have the same meaning as understood by those skilled in the art.
[0033] Unless otherwise specified, the test materials and reagents used in the following examples are commercially available or prepared by known methods.
[0034] Unless otherwise specified, all techniques or conditions described in the embodiments can be performed in accordance with the techniques or conditions described in the literature in this field or in the product manual. Unless otherwise specified, the quantitative experiments in the following embodiments are all repeated three times or more, and the results are averaged.
[0035] Example 1: This embodiment provides a method for preparing an acid-resistant non-precious metal catalyst, including the following steps: (1) Preparation of the carrier: 10 g of melamine was placed in a magnetic boat and calcined at 500 °C in air for 4 h. After cooling to room temperature, it was ground into a solid powder. (2) Modification of the carrier: 2 g of solid powder obtained in step (1) was placed in a container, 10 mL of concentrated sulfuric acid (98%) was added, and the mixture was stirred for 1 h. Then, 10 mL of deionized water was slowly added. When the mixture changed from a viscous mud-like consistency to a white transparent solution, 33.3 mL of ethanol was added and stirred for 12 h. The mixture was filtered and washed with deionized water until neutral. The solution was then dried in an oven at 120 ℃ for 20 h to obtain the modified carrier. (The SEM image of the modified carrier is shown in Figure 1.) Figure 1 As shown in the figure, the modified catalyst support exhibits a distinct layered porous structure. This structure has a higher specific surface area, which can anchor more metal atoms and increase the metal loading rate. (3) Preparation of impregnation solution: Weigh 0.2 g of cobalt chloride and 2 g of nickel chloride into a container, dissolve them in 50 mL of deionized water to obtain a metal impregnation solution; (4) Preparation of unactivated catalyst: The modified support from step (2) was added to the metal impregnation solution prepared in step (3), and after thorough mixing, it was stirred for 12 h and dried to obtain the unactivated catalyst. (5) Activation of the catalyst: The unactivated catalyst obtained in step (4) was placed in a tube furnace and activated at 1℃ / min from room temperature to 400℃ for 5 h under H2 / Ar atmosphere to obtain a solid catalyst.
[0036] (6) Catalyst functionalization: Add 5g of the solid catalyst obtained in step (5) to 50mL of 10wt% H2SO4 aqueous solution and stir for 12h to obtain the final acid-resistant non-precious metal catalyst. (The TEM image is shown below.) Figure 2 As shown in the figure, the obtained solid acid catalyst has uniform and evenly distributed active metal particles of uniform size. Example 2: The difference between this embodiment and Embodiment 1 is that: In step (3), 0.1 g of cobalt chloride and 1 g of nickel chloride are weighed into a container and dissolved in 50 mL of deionized water to obtain a metal impregnation solution. The remaining steps are the same.
[0037] Example 3: The difference between this embodiment and Embodiment 1 is that: In step (2), the ratio of solid powder, concentrated sulfuric acid, deionized water and ethanol is 3 g: 20 mL: 20 mL: 60 mL.
[0038] Example 4: The difference between this embodiment and Embodiment 1 is that: In step (2), the ratio of solid powder, concentrated sulfuric acid, deionized water and ethanol is 1 g: 5 mL: 5 mL: 15 mL.
[0039] Example 5: The difference between this embodiment and Embodiment 1 is that: In step (3), weigh 2 g of cobalt chloride and 2 g of nickel chloride into a container, dissolve them in 50 mL of deionized water to obtain a metal impregnation solution. The remaining steps are the same.
[0040] Example 6: The difference between this embodiment and Embodiment 1 is that: In step (3), 1g of cobalt nitrate and 1.5g of nickel nitrate are weighed into a container and dissolved in 50 mL of deionized water to obtain a metal impregnation solution. The remaining steps are the same.
[0041] Application Example 1: 15 mL of 25 wt% H2SO4 aqueous solution, 0.2 g nitrobenzene, 3 mg hexadecyltrimethylammonium chloride, and 0.01 g of the acid-resistant non-precious metal catalyst prepared in Example 1 were added to a high-temperature and high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 60 °C, the hydrogen pressure was 0.5 MPa, the stirring rate was 1000 r / min, and the reaction time was 12 h. After the reaction was stopped, the temperature was allowed to drop to room temperature, the reaction solution was taken out, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 99.7%, and the selectivity for p-aminophenol was 85.4% (the selectivity for p-aminophenol was obtained by dividing the aminophenol yield by the nitrobenzene conversion rate).
[0042] Application Example 2: 15 mL of 25 wt% H2SO4 aqueous solution, 0.2 g nitrobenzene, 3 mg hexadecyltrimethylammonium chloride, and 0.01 g of the acid-resistant non-precious metal catalyst prepared in Example 2 were added to a high-temperature and high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 60 °C, the hydrogen pressure was 0.5 MPa, the stirring rate was 1000 r / min, and the reaction time was 12 h. After the reaction was stopped, the temperature was allowed to drop to room temperature, the reaction solution was taken out, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 99.6%, and the selectivity for p-aminophenol was 50.1%.
[0043] Application Example 3: 15 mL of 25 wt% H2SO4 aqueous solution, 0.2 g nitrobenzene, 3 mg hexadecyltrimethylammonium chloride, and 0.01 g of the acid-resistant non-precious metal catalyst prepared in Example 1 were added to a high-temperature and high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 80 °C, the hydrogen pressure was 0.5 MPa, the stirring rate was 1000 r / min, and the reaction time was 12 h. After the reaction was stopped, the temperature was allowed to drop to room temperature, the reaction solution was taken out, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 98.7%, and the selectivity for p-aminophenol was 75.4%.
[0044] Application Example 4: 15 mL of 25 wt% H2SO4 aqueous solution, 0.2 g nitrobenzene, 3 mg hexadecyltrimethylammonium chloride, and 0.01 g of the acid-resistant non-precious metal catalyst prepared in Example 1 were added to a high-temperature and high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 100 °C, the hydrogen pressure was 0.5 MPa, the stirring rate was 1000 r / min, and the reaction time was 12 h. After the reaction was stopped, the temperature was allowed to drop to room temperature, the reaction solution was taken out, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 99.4%, and the selectivity for p-aminophenol was 70.1%.
[0045] Application Example 5: 15 mL of 25 wt% H2SO4 aqueous solution, 0.2 g nitrobenzene, 3 mg hexadecyltrimethylammonium chloride, and 0.01 g of the acid-resistant non-precious metal catalyst prepared in Example 1 were added to a high-temperature and high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 60 °C, the hydrogen pressure was 1 MPa, the stirring rate was 1000 r / min, and the reaction time was 12 h. After the reaction was stopped, the temperature was allowed to drop to room temperature, the reaction solution was taken out, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 99.3%, and the selectivity for p-aminophenol was 65.3%.
[0046] Application Example 6: 15 mL of 25 wt% H2SO4 aqueous solution, 0.2 g nitrobenzene, 3 mg hexadecyltrimethylammonium chloride, and 0.01 g of the acid-resistant non-precious metal catalyst prepared in Example 1 were added to a high-temperature and high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 60 °C, the hydrogen pressure was 1.5 MPa, the stirring rate was 1000 r / min, and the reaction time was 12 h. After the reaction was stopped, the temperature was allowed to drop to room temperature, the reaction solution was taken out, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 99.9%, and the selectivity for aminophenol was 48.2%.
[0047] Application Example 7: 15 mL of 15 wt% H2SO4 aqueous solution, 0.2 g nitrobenzene, 3 mg hexadecyltrimethylammonium chloride, and 0.01 g of the acid-resistant non-precious metal catalyst prepared in Example 1 were added to a high-temperature and high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 60 °C, the hydrogen pressure was 0.5 MPa, the stirring rate was 1000 r / min, and the reaction time was 12 h. After the reaction was stopped, the temperature was allowed to drop to room temperature, the reaction solution was taken out, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 99.4%, and the selectivity for p-aminophenol was 65.3%.
[0048] Application Example 8: 15 mL of 5wt% H2SO4 aqueous solution, 0.2 g of nitrobenzene, 3 mg of hexadecyltrimethylammonium chloride, and 0.01 g of the acid-resistant non-precious metal catalyst prepared in Example 1 were added to a high-temperature and high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 60 °C, the hydrogen pressure was 0.5 MPa, the stirring rate was 1000 r / min, and the reaction time was 12 h. After the reaction was stopped, the temperature was allowed to drop to room temperature, the reaction solution was taken out, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 99.8%, and the selectivity for aminophenol was 48.6%.
[0049] Comparative Example 1: The difference between this comparative example and Example 1 is as follows: Cobalt chloride was not added in step (3). The remaining steps are the same.
[0050] This comparative example was applied to the selective hydrogenation reaction of nitrobenzene, and the application steps were the same as in Application Example 1. The catalyst was recovered by filtration, and the filtrate was analyzed by high performance liquid chromatography. The conversion rate of nitrobenzene was 98.8%, and the selectivity for p-aminophenol was 20.5%.
[0051] Comparative Example 2: The difference between this comparative example and Example 1 is as follows: Nickel chloride was not added in step (3). The remaining steps are the same.
[0052] This comparative example was applied to the selective hydrogenation reaction of nitrobenzene, and the application steps were the same as in Application Example 1. The catalyst was recovered by filtration, and the filtrate was analyzed by high performance liquid chromatography. The conversion rate of nitrobenzene was 99.7%, and the selectivity for p-aminophenol was 38.2%.
[0053] Comparative Example 3: The difference between this comparative example and Example 1 is as follows: Steps (1) and (2) are replaced by: placing 5 g of commercial titanium dioxide (P25) powder in a muffle furnace and calcining it at 400°C in air for 4 hours, then cooling and grinding it. The resulting solid is used directly as a carrier. The remaining steps are the same.
[0054] This comparative example was applied to the selective hydrogenation reaction of nitrobenzene, and the application steps were the same as in Application Example 1. The catalyst was recovered by filtration, and the filtrate was analyzed by high performance liquid chromatography. The conversion rate of nitrobenzene was 85.7%, and the selectivity for p-aminophenol was 8.9%.
[0055] Comparative Example 4: The difference between this comparative example and Example 1 is as follows: Steps (1) and (2) are replaced by: placing 5 g of commercial silica (SBA-15) powder in a muffle furnace and calcining it at 400 °C in air for 4 hours, then cooling and grinding it. The resulting solid is used directly as a carrier. The remaining steps are the same.
[0056] This comparative example was applied to the selective hydrogenation reaction of nitrobenzene, with the same application steps as in Application Example 1. The catalyst was recovered by filtration, and the filtrate was analyzed by high performance liquid chromatography. The conversion rate of nitrobenzene was 64.2%, and the selectivity for p-aminophenol was 21.2%.
[0057] Comparative Example 5: The difference between this comparative example and Example 1 is as follows: Steps (1) and (2) are replaced by grinding 5 g of commercial coconut shell-based activated carbon powder and using it directly as a carrier. The remaining steps are the same.
[0058] This comparative example was applied to the selective hydrogenation reaction of nitrobenzene, with the same application steps as in Application Example 1. The catalyst was recovered by filtration, and the filtrate was analyzed by high performance liquid chromatography. The conversion rate of nitrobenzene was 50.1%, and the selectivity for p-aminophenol was 27.2%.
[0059] Comparative Example 6: The difference between this comparative example and Example 1 is as follows: Steps (1) and (2) are replaced by: placing 5 g of commercial γ-alumina powder in a muffle furnace and calcining it at 400 °C in air for 4 hours, then cooling and grinding it. The resulting solid is used directly as a carrier. The remaining steps are the same.
[0060] This comparative example was applied to the selective hydrogenation reaction of nitrobenzene, and the application steps were the same as in Application Example 1. The catalyst was recovered by filtration, and the filtrate was analyzed by high performance liquid chromatography. The conversion rate of nitrobenzene was 21.0%, and the selectivity for p-aminophenol was 12.1%.
[0061] Comparative Example 7: The difference between this comparative example and Example 1 is as follows: Step (2) was not performed; the powder obtained in step (1) was used directly as a carrier. The remaining steps were the same.
[0062] This comparative example was applied to the selective hydrogenation reaction of nitrobenzene, and the application steps were the same as in Application Example 1. The catalyst was recovered by filtration, and the filtrate was analyzed by high performance liquid chromatography. The conversion rate of nitrobenzene was 99.3%, and the selectivity of p-aminophenol was 33.4%.
[0063] Comparative Example 8: The difference between this comparative example and Example 1 is as follows: In step (3), 0.01 g of cobalt chloride and 0.1 g of nickel chloride are weighed into a container and dissolved in 50 mL of deionized water to obtain a metal impregnation solution. The remaining steps are the same.
[0064] Comparative Example 9: 15 mL of 25 wt% H2SO4 aqueous solution, 0.2 g nitrobenzene, 3 mg hexadecyltrimethylammonium chloride, and 0.01 g of the acid-resistant non-precious metal catalyst prepared in Comparative Example 8 were added to a high-temperature and high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 60 °C, the hydrogen pressure was 0.5 MPa, the stirring rate was 1000 r / min, and the reaction time was 12 h. After the reaction was stopped, the temperature was allowed to drop to room temperature, the reaction solution was taken out, the catalyst was recovered by filtration, and the filtrate was analyzed by high-performance liquid chromatography. The conversion rate of nitrobenzene was 99.1%, and the selectivity for p-aminophenol was 23.1%.
[0065] Comparative Example 10: 15 mL of 25 wt% H2SO4 aqueous solution, 0.2 g nitrobenzene, 3 mg hexadecyltrimethylammonium chloride, and 0.01 g of commercially available 5% Pd / C catalyst were added to a high-temperature and high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 60 °C, the hydrogen pressure was 0.5 MPa, the stirring rate was 1000 r / min, and the reaction time was 12 h. After the reaction was stopped, the temperature was allowed to drop 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 99.3%, and the selectivity for p-aminophenol was 18.4%.
[0066] Catalyst cycle stability test The acid-resistant non-precious metal catalyst prepared in Example 1 was used in the selective hydrogenation reaction of nitrobenzene to investigate its recycling performance. 15 mL of 25 wt% H₂SO₄ aqueous solution, 0.2 g of nitrobenzene, 3 mg of hexadecyltrimethylammonium chloride, and 0.01 g of the acid-resistant non-precious metal catalyst prepared in Example 1 were added to a high-temperature, high-pressure reactor. The air in the reactor was replaced three times with hydrogen. The temperature was raised to 60 °C, the hydrogen pressure to 0.5 MPa, the stirring rate to 1000 r / min, and the reaction time to 12 h. After the reaction was stopped, the temperature was allowed to drop to room temperature, the reaction solution was removed, and the catalyst was recovered by filtration. The recovered catalyst was washed three times with deionized water and three times with ethanol, and then dried in an oven at 80 °C for 12 h. The recovered catalyst was directly used in the next cycle reaction under the same conditions, and the reactor was recycled five times. The reaction solution was analyzed by high-performance liquid chromatography (HPLC) to calculate the nitrobenzene conversion and the selectivity for p-aminophenol. The results are as follows: Figure 3 As shown, the prepared acid-resistant non-precious metal catalyst exhibits excellent stability in strong acid and high temperature environments, and its catalytic activity remains basically unchanged within 5 cycles, while the selectivity of p-aminophenol remains basically stable.
[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing an acid-resistant non-precious metal catalyst, characterized in that, Includes the following steps: (1) Modification of the carrier: Melamine was calcined and cooled; ground into powder; concentrated sulfuric acid, deionized water and ethanol were added in sequence and stirred; filtered, washed and dried to obtain the modified carrier; (2) Activation of catalyst: Weigh cobalt salt and nickel salt, dissolve them to obtain metal impregnation solution; add the modified support obtained in step (1) and mix; The solid catalyst was obtained by calcination and activation; H2SO4 solution was added and stirred to obtain the final product.
2. The preparation method according to claim 1, characterized in that, In step (1), the calcination method is to calcine in an air atmosphere at 400-500 ℃ for 3-4 h; the ratio of powder, concentrated sulfuric acid, deionized water and ethanol is 1-3 g: 5-20 mL: 5-20 mL: 15-60 mL.
3. The preparation method according to claim 1, characterized in that, In step (1), the filtration and washing method is to filter and wash with deionized water until neutral; the drying conditions are to dry at 120-130℃ for 8-24 h.
4. The preparation method according to claim 1, characterized in that, In step (2), the cobalt salt is one of cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt acetate, cobalt perchlorate, cobalt bromide, cobalt oxalate, cobalt fluoride, cobalt carbonate, cobalt phosphate, cobalt sulfite, hexaamminecobalt trichloride, and cobalt hydroxide; the nickel salt is one of nickel chloride, nickel sulfate, nickel nitrate, nickel acetate, nickel perchlorate, nickel bromide, nickel oxalate, nickel fluoride, nickel carbonate, nickel phosphate, nickel sulfite, hexaamminecobalt trichloride, and hexaamminecobalt sulfate; the solvent used for dissolution is deionized water, wherein the ratio of cobalt salt, nickel salt, and deionized water is 0.01-2 g: 0.1-2 g: 50 mL; the mixing time is 12-36 h.
5. The preparation method according to claim 1, characterized in that, In step (2), the calcination activation conditions are: calcination activation at 400-600℃ for 2-5 h in a hydrogen and argon atmosphere.
6. The preparation method according to claim 1, characterized in that, In step (2), the ratio of solid catalyst to H2SO4 solution is 1-10 g: 50-100 mL; the concentration of H2SO4 solution is 10-25 wt%; and the stirring time is 12-24 h.
7. An acid-resistant non-precious metal catalyst prepared by the preparation method according to any one of claims 1-6.
8. The application of the acid-resistant non-precious metal catalyst according to claim 7 in the synthesis of p-aminophenol from nitrobenzene.
9. The application according to claim 8, characterized in that, The application method is as follows: Weigh the acid-resistant non-precious metal catalyst described in claim 7, use nitrobenzene, hexadecyltrimethylammonium bromide and hydrogen as reaction raw materials, and dilute sulfuric acid as reaction solvent to carry out the reaction to obtain the target product p-aminophenol.
10. The application according to claim 9, characterized in that, The specific application method is as follows: Weigh 0.01-0.04 g of acid-resistant non-precious metal catalyst, 0.2-1 g of nitrobenzene, 1-10 mg of hexadecyltrimethylammonium bromide, and 5-15 mL of H2SO4 solution into a reaction vessel, and purge with 0.1-5 MPa of hydrogen gas. React at 30-180 ℃ and 100-1000 r / min for 1-36 h to obtain the target product p-aminophenol; the concentration of dilute sulfuric acid is 5-25 wt%.