Method for preparing p-aminophenol through nitrobenzene hydrogenation

Abstract

The invention discloses a method for preparing p-aminophenol through nitrobenzene hydrogenation, which comprises the following steps: adding a few-layer graphene coated Ni catalyst, an acid, nitrobenzene and a solvent into a polytetrafluoroethylene lining, ultrasonically mixing uniformly, then putting into a reaction kettle, sealing, replacing air in the reaction kettle with hydrogen, and reacting for 2-4 hours; and raising the temperature to a reaction temperature for reaction to obtain aminophenol. The few-layer graphene coated Ni catalyst is used for catalyzing nitrobenzene hydrogenation to prepare p-aminophenol, the synthesis route of the catalyst is simple, raw materials are cheap and easy to obtain, and compared with a traditional reduction method (such as iron powder reduction), the catalytic hydrogenation route is more environmentally friendly, high in atom utilization rate, easy and convenient to operate and high in economic benefit. The obtained few-layer graphene coated Ni catalyst has the advantages of mild reaction conditions, high product selectivity, easiness in separation and recovery, good cycling stability and the like in catalyzing nitrobenzene hydrogenation to prepare p-aminophenol.

Description

Technical Field

[0001] The invention relates to the field of organic synthesis, and in particular to a method for preparing p-aminophenol by hydrogenating nitrobenzene. Background Art

[0002] Para-aminophenol (PAP) is an important fine chemical intermediate, widely used in the pharmaceutical industry (such as the preparation of paracetamol, paracetamol, vitamin B, etc.), dye industry (such as the preparation of acid dyes, sulfur dyes, fur dyes, etc.), rubber industry (such as the preparation of paraphenylenediamine antioxidants), fertilizer industry, etc. The main production processes of para-aminophenol include nitrobenzene hydrogenation, 4-nitrophenol reduction, 4-chloronitrobenzene nucleophilic substitution, 4-hydroxyacetophenone oxime Beckmann rearrangement, etc. Among them, the nitrobenzene hydrogenation process is simple, low cost, and less polluting, so it has attracted widespread attention from researchers.

[0003] The existing schemes for preparing p-aminophenol by hydrogenation of nitrobenzene mainly include metal chemical reduction, catalytic hydrogenation and electrolytic reduction. Among them, the preparation of p-aminophenol by catalytic hydrogenation of nitrobenzene has attracted widespread interest from researchers due to its short process flow, low energy consumption, small negative environmental impact and great industrial production prospects. The current technology of catalytic hydrogenation of nitrobenzene to synthesize p-aminophenol generally produces intermediates in the nitrobenzene hydrogenation process (such as nitrosobenzene, phenylhydroxylamine, azoxybenzene, azobenzene, 1,2-diphenylhydrazine), and may also produce by-products such as aniline, o-aminophenol, 4,4′-diaminodiphenyl ether, and p-hydroxydiphenylamine. Therefore, the development of highly selective catalysts is the core, and the key to the catalyst is to construct efficient active components. Commonly used active components are precious and base metal-based catalysts or their coupled catalysts. In order to further improve the selectivity of the reaction process or promote the stability of the process under acidic conditions, a frequently used technical solution is to modify the precious and base metal active components, such as surface modification of active components, core-shell structure coating of active components, sacrificial agent coupling of active components, etc., to inhibit a series of side reactions such as transitional hydrogenation of nitrobenzene and condensation of target products into ethers and diphenylamine.

[0004] CN103357407A discloses a preparation method and application of a catalyst for preparing p-aminophenol from nitrobenzene in one step, and reduces the poisoning effect of sulfide on the active component platinum by adding metal alum. CN 103570563 A discloses a process for directly synthesizing p-aminophenol from nitrobenzene by hydrogenation, and uses a nitrogen-doped carbon-protected acid-resistant hydrogenation catalyst to achieve high activity and high stability operation of the process. CN111514941 A discloses a catalyst and method for catalyzing the one-step synthesis of p-aminophenol by hydrogenation of nitrobenzene, and uses a polystyrene group modified NiSi / activated carbon catalyst with sulfonic acid functionalization to avoid acid corrosion of the hydrogenation catalyst and improve the selectivity of the target product. CN117599851A discloses a new catalyst for catalytic hydrogenation of nitrobenzene to synthesize p-aminophenol, and its preparation method and application, and develops a metal cluster catalyst composed of a metal core and peripheral ligands, and improves the acid resistance of the catalyst and the yield of the target product through a clear atomic stacking form and coordination environment. CN 117181003 A discloses a method for preparing a Co@CM multi-channel ceramic catalytic membrane for hydrogenation of p-nitrophenol. The method uses a carbon-nitrogen-wrapped Co nanoparticle and loads it on a multi-channel ceramic membrane, thereby inhibiting the loss of Co particles during the reaction process and increasing the acid resistance, cycle stability and selectivity of the catalyst for p-aminophenol. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing p-aminophenol by hydrogenating nitrobenzene in view of the defects of the prior art.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a method for preparing p-aminophenol by hydrogenating nitrobenzene, comprising the following steps: adding a Ni catalyst wrapped in a few-layer graphene, an acid, nitrobenzene and a solvent into a polytetrafluoroethylene liner, ultrasonically mixing them uniformly and then putting them into a reactor and sealing them, replacing the air in the reactor with hydrogen, heating them to a reaction temperature for reaction to obtain aminophenol.

[0007] Furthermore, the few-layer graphene-wrapped Ni catalyst is Ni particles wrapped inside the few-layer graphene, wherein the Ni particle size is 1 to 50 nanometers, the mass content is 5% to 90%, and the number of the few-layer graphene layers is 1 to 3 layers.

[0008] Furthermore, a few-layer graphene-wrapped Ni catalyst is prepared by using metal salt, organic amine and carbon source as raw materials through hydrothermal treatment to obtain a precursor, which is then calcined in a N2 atmosphere and then treated with a sulfuric acid solution.

[0009] Furthermore, the metal salt is one or a mixture of two or more of nickel acetate, nickel nitrate, nickel sulfate, and nickel chloride; the organic amine is one or a mixture of two or more of ethanolamine, urea, dicyandiamide, and hexamethylenetetramine; and the carbon source is one or a mixture of two or more of furfural, furfuryl alcohol, glycerol, glucose, fructose, and lactose.

[0010] Furthermore, the molar ratio of the metal salt, the organic amine, and the carbon source is 1:(0.5-2.0):(2.5-5.5).

[0011] Furthermore, the reaction conditions of the hydrothermal treatment are 100~180℃ for 2.0~24.0h; the calcination conditions are heating to 400~800℃ at 3.0~5.0℃ / min and maintaining for 2.0~8.0h; the concentration of the sulfuric acid solution is 0.1~2.0M, the temperature is 25~80℃, and the treatment time is 2.0~24.0h.

[0012] Furthermore, the dosage ratio of the oligolayer graphene-wrapped Ni catalyst: acid: nitrobenzene: solvent is: 5 mg: (0.1-1.0 mmol): (0.5 mmol): (5.0 mL).

[0013] Furthermore, the acid is hydrochloric acid, sulfuric acid or acetic acid.

[0014] Furthermore, the solvent is one of water, methanol, and ethanol, or a mixture of two or more thereof.

[0015] Furthermore, the hydrogen pressure is 0.1~1.0 MPa, the reaction temperature is 25~60°C, and the reaction time is 0.5~2.0 h.

[0016] The present invention adopts a few-layer graphene-wrapped Ni catalyst to catalyze nitrobenzene hydrogenation to prepare p-aminophenol. The catalyst has a simple synthesis route, and the raw materials are cheap and easily available. The catalytic hydrogenation route is more environmentally friendly than the traditional reduction method (such as iron powder reduction), has a high atomic utilization rate, is easy to operate, and has high economic benefits. The obtained few-layer graphene-wrapped Ni catalyst has the advantages of mild reaction conditions, high product selectivity, easy separation and recovery, good cycle stability, etc. in catalyzing nitrobenzene hydrogenation to prepare p-aminophenol. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 XRD spectra of the few-layer graphene-wrapped Ni catalysts obtained in Examples 1 to 3 of the present invention.

[0018] Figure 2 Transmission electron microscope photographs of the few-layer graphene-wrapped Ni catalysts prepared in Examples 1 to 3 of the present invention.

[0019] Figure 3These are high-resolution transmission electron microscopy photographs of the few-layer graphene-wrapped Ni catalysts obtained in Examples 1 to 3 of the present invention.

[0020] Figure 4 This is a photograph of a Ni catalyst wrapped in a few-layer graphene obtained by using a magnet to separate the specific embodiment 3 of the present invention.

[0021] Figure 5 Schematic diagram of the process of hydrogenating nitrobenzene to prepare p-aminophenol. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0023] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatuses.

[0024] Example 1

[0025] This embodiment is a method for preparing a few-layer graphene-wrapped Ni catalyst for catalyzing the hydrogenation of nitrobenzene to prepare p-aminophenol, which specifically includes the following steps.

[0026] (1) Take 0.5 mmol nickel chloride, 0.5 mmol nickel nitrate, 1.0 mmol ethylenediamine, 2.0 mmol glycerol and 2.0 mmol glucose in 60 mL deionized water and stir to dissolve.

[0027] (2) The obtained solution was placed in a polytetrafluoroethylene hydrothermal autoclave, sealed, and placed in a 100 °C oven for hydrothermal treatment for 24.0 h. After the hydrothermal reaction was completed, the obtained solid product was separated by centrifugation and placed in an 80 °C oven for drying for 12.0 h.

[0028] (3) The dried solid product obtained in (2) was placed in an Ar atmosphere, heated to 400 °C at 3.0 °C / min, and maintained for 6.0 h.

[0029] (4) The calcined sample was treated with 0.1 M hydrochloric acid at 25 °C for 24.0 h, and finally washed with deionized water and anhydrous ethanol and dried at 80 °C to obtain the Ni@FLG-1 catalyst.

[0030] Example 2

[0031] This embodiment is a method for preparing a few-layer graphene-wrapped Ni catalyst for catalyzing the hydrogenation of nitrobenzene to prepare p-aminophenol, which specifically includes the following steps.

[0032] (1) Take 1.0 mmol nickel acetate hexahydrate, 1.0 mmol urea, 1.0 mmol dicyandiamide, 4.0 mmol glucose and 4.0 mmol lactose in 60 mL deionized water and stir to dissolve.

[0033] (2) The obtained solution was placed in a polytetrafluoroethylene hydrothermal autoclave, sealed, and placed in a 150°C oven for hydrothermal treatment for 18 h. After the hydrothermal reaction was completed, the obtained solid product was separated by centrifugation and placed in an 80°C oven for drying for 12 h.

[0034] (3) The dried solid product obtained in (1) was placed in an Ar atmosphere, heated to 600 °C at 3.0 °C / min, and maintained for 4.0 h.

[0035] (4) The calcined sample was treated with 1.0 M hydrochloric acid at 50 °C for 10.0 h, washed with deionized water and anhydrous ethanol, and dried at 80 °C to obtain the Ni@FLG-2 catalyst.

[0036] Example 3

[0037] This embodiment is a method for preparing a few-layer graphene-wrapped Ni catalyst for catalyzing the hydrogenation of nitrobenzene to prepare p-aminophenol, which specifically includes the following steps.

[0038] (1) Weigh 1.0 mmol nickel sulfate, 1.0 mmol dicyandiamide, 2.0 mmol EDTA, 8.0 mmol fructose and 4.0 mmol lactose respectively into 60 mL deionized water and stir to dissolve.

[0039] (2) The obtained solution was placed in a polytetrafluoroethylene hydrothermal autoclave, sealed, and placed in a 180°C oven for hydrothermal treatment for 5.0 h. After the hydrothermal reaction was completed, the obtained solid product was separated by centrifugation and placed in an 80°C oven for drying for 12 h.

[0040] (3) The dried solid product obtained in (1) was placed in an Ar atmosphere, heated to 700 °C at 3.0 °C / min, and maintained for 2.0 h.

[0041] (4) The calcined sample was treated with 2.0 M hydrochloric acid at 80 °C for 2.0 h and finally washed with deionized water and anhydrous ethanol and dried at 80 °C to obtain the Ni@FLG-3 catalyst.

[0042] Figure 1 XRD spectra of the catalysts Ni@FLG-1, Ni@FLG-2, and Ni@FLG-3 prepared in Examples 1 to 3. It can be seen from the figure that the four catalysts all have a broad peak at about 26°, indicating that the catalysts have a graphite carbon structure. The diffraction peaks of 44.5°, 51.9°, and 76.8° indicate that the catalysts still have Ni retained after strong acid washing, and Ni is in a metallic state.

[0043] Figure 2 Transmission electron microscope photos of the catalysts Ni@FLG-1, Ni@FLG-2, and Ni@FLG-3 prepared in Examples 1 to 3. It can be seen from the figure that the four catalysts all present a flower cluster structure, and the Ni particles are evenly distributed therein.

[0044] Figure 3 High-resolution transmission electron microscopy photos of the catalysts Ni@FLG-1, Ni@FLG-2, and Ni@FLG-3 prepared in Examples 1 to 3. It can be seen from the figure that Ni in the four catalysts is wrapped by few-layer graphene.

[0045] Figure 4 This is a photograph of a few-layer graphene-wrapped Ni catalyst prepared in Specific Example 3 of the present invention being separated using a magnet. As can be seen from the figure, the few-layer graphene-wrapped Ni catalyst involved in the present invention is magnetic and can be quickly separated by a magnet.

[0046] Example 5

[0047] This example is to use a few-layer graphene wrapped Ni catalyst to catalyze the hydrogenation of nitrobenzene to prepare p-aminophenol ( Figure 5 ), specifically including the following steps.

[0048] The few-layer graphene-wrapped Ni catalyst (Ni@FLG-1, Ni@FLG-2, Ni@FLG-3, 5.0 mg), acid (one of hydrochloric acid, sulfuric acid, acetic acid, 0.1-1.0 mmol), nitrobenzene (0.5 mmol), solvent (one of water, methanol, ethanol or a mixture of two or more, 5.0 mL) were added to a 50 mL polytetrafluoroethylene liner, ultrasonically mixed and then placed in a reactor and sealed. After replacing the air in the reactor with hydrogen (0.1-1.0 MPa), the temperature was raised to the reaction temperature (25-60 °C) and the reaction was carried out for 0.5-2.0 h. After the reaction was completed, the catalyst was separated by a magnet and the product was analyzed by high performance liquid chromatography. Table 1 is the few-layer graphene-wrapped Ni catalyst for hydrogenation of nitrobenzene to p-aminophenol.

[0049] Figure 1

[0050]

[0051] As shown in Table 1, using 5.0 mg Ni@FLG-3 as catalyst, 1.0 mmol sulfuric acid, 0.5 mmol nitrobenzene, and water as solvent, the reaction was carried out at 60 °C and 1.0 MPa hydrogen pressure for 2.0 h, and nitrobenzene can be completely converted into p-aminophenol.

[0052] Example 5

[0053] This embodiment is a cyclic stability test of hydrogenating nitrobenzene to p-aminophenol using a few-layer graphene-wrapped Ni catalyst (Ni@FLG-3), which specifically includes the following steps.

[0054] 5.0 mg of Ni catalyst (Ni@FLG-3) wrapped with few-layer graphene, 1.0 mmol of sulfuric acid, nitrobenzene (0.5 mmol), and 5 mL of water were added to a 50 mL polytetrafluoroethylene liner, ultrasonically mixed and then sealed in a reactor. After replacing the air in the reactor with hydrogen (1.0 MPa), the temperature was raised to the reaction temperature (60 °C) and the reaction was continued for 2.0 h. After the reaction, the catalyst was separated by a magnet, washed with water three times, and then directly used for the cycle test. The product was analyzed by high performance liquid chromatography. Table 2 shows the cycle stability of nitrobenzene hydrogenation to oxyazobenzene catalyzed by Ni catalyst (Ni@FLG-3) wrapped with few-layer graphene.

[0055] Table 2

[0056]

[0057] As shown in Table 2, Ni@FLG-3 exhibits excellent catalytic activity and cyclic stability in the catalytic hydrogenation of nitrobenzene to p-aminophenol, and no deactivation occurs after ten cycles.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing p-aminophenol by hydrogenating nitrobenzene, characterized in that The following steps are involved: The Ni catalyst wrapped in a few-layer graphene, acid, nitrobenzene and solvent are added into a polytetrafluoroethylene liner, and after being uniformly mixed by ultrasonication, they are placed into a reactor and sealed. After the air in the reactor is replaced by hydrogen, the temperature is raised to the reaction temperature for reaction to obtain aminophenol.

2. The method for preparing p-aminophenol by hydrogenating nitrobenzene according to claim 1, characterized in that: The few-layer graphene-wrapped Ni catalyst is Ni particles wrapped inside the few-layer graphene, wherein the Ni particle size is 1 to 50 nanometers, the mass content is 5% to 90%, and the few-layer graphene has 1 to 3 layers.

3. The method for preparing p-aminophenol by hydrogenation of nitrobenzene according to claim 2, characterized in that: The few-layer graphene-wrapped Ni catalyst is prepared by using metal salt, organic amine and carbon source as raw materials and hydrothermally treating the precursor, and then calcining the precursor in a N2 atmosphere and treating the catalyst with a sulfuric acid solution.

4. The method for preparing p-aminophenol by hydrogenating nitrobenzene according to claim 3, characterized in that: The metal salt is one of nickel acetate, nickel nitrate, nickel sulfate, and nickel chloride, or a mixture of two or more thereof; the organic amine is one of ethanolamine, urea, dicyandiamide, and hexamethylenetetramine, or a mixture of two or more thereof; and the carbon source is one of furfural, furfuryl alcohol, glycerol, glucose, fructose, and lactose, or a mixture of two or more thereof.

5. The method for preparing p-aminophenol by hydrogenating nitrobenzene according to claim 3, characterized in that: The molar ratio of the metal salt, the organic amine and the carbon source is 1:(0.5-2.0):(2.5-5.5).

6. The method for preparing p-aminophenol by hydrogenating nitrobenzene according to claim 3, characterized in that: The reaction conditions of the hydrothermal treatment are 100-180°C for 2.0-24.0h; the calcination conditions are heating to 400-800°C at 3.0-5.0°C / min and maintaining for 2.0-8.0h; the concentration of the sulfuric acid solution is 0.1-2.0M, the temperature is 25-80°C, and the treatment time is 2.0-24.0h.

7. The method for preparing p-aminophenol by hydrogenating nitrobenzene according to claim 1, characterized in that: The dosage ratio of the few-layer graphene-wrapped Ni catalyst: acid: nitrobenzene: solvent is: 5 mg: (0.1-1.0 mmol): (0.5 mmol): (5.0 mL).

8. The method for preparing p-aminophenol by hydrogenating nitrobenzene according to claim 1, characterized in that: The acid is hydrochloric acid, sulfuric acid or acetic acid.

9. The method for preparing p-aminophenol by hydrogenating nitrobenzene according to claim 1, characterized in that: The solvent is one of water, methanol and ethanol or a mixture of two or more thereof.

10. The method for preparing p-aminophenol by hydrogenating nitrobenzene according to claim 1, characterized in that: The hydrogen pressure is 0.1-1.0 MPa, the reaction temperature is 25-60°C, and the reaction time is 0.5-2.0 h.

Images