Single-layer graphene coated Ni catalyst as well as preparation method and application thereof
By catalyzing the nitrobenzene hydrogenation reaction with oligolayer graphene-encapsulated Ni catalyst, the problems of high cost and difficulty in separation of by-products in the prior art are solved, and catalytic effects with high selectivity and cycle stability are achieved.
Patent Information
- Application Number
- CN202411943997.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-03-25
AI Technical Summary
In the prior art, when catalyzing the hydrogenation of nitrobenzene to prepare phenylhydroxylamine or aniline, there are problems such as high cost and easy generation of by-products to increase subsequent separation energy consumption, and it is difficult to effectively regulate the reaction path to obtain high value-added products.
The Ni catalyst is prepared by hydrothermal treatment and sulfuric acid solution treatment, combined with ultrasonic mixing and magnet separation technology, and is used to catalyze the hydrogenation reaction of nitrobenzene.
The mildness of catalytic reaction conditions, high selectivity to the product, easy separation and recovery and cycle stability are achieved, which reduces production costs and increases the added value of the product.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] The invention relates to the field of organic synthesis, and in particular to a method for preparing a few-layer graphene-wrapped Ni catalyst machine and application thereof in catalyzing nitrobenzene hydrogenation to prepare phenylhydroxylamine or aniline. Background Art
[0002] Aniline is an important basic raw material for the chemical industry, and hydroxyaniline is a high value-added intermediate in the modern dye industry and fine chemical industry. Both can be used to produce dyes, drugs, rubber additives, pesticides and other chemicals, and their demand is on the rise. At present, the main commercial route for the production of the two chemicals is to use stoichiometric reducing agents (such as Zn, Fe, etc.) to non-catalytically reduce nitroaromatics, but this method consumes a large amount of metal reducing agents, the product distribution is almost unadjustable and poses a potential threat to the environment. With the research and development and industrial application of heterogeneous catalytic nitrobenzene hydrogenation technology using precious and base metal nanomaterials, the production of aniline has made certain breakthroughs. However, the current nitrobenzene hydrogenation process involves a variety of high value-added intermediates, such as nitrosobenzene, phenylhydroxylamine, azoxybenzene, azobenzene, 1,2-diphenylhydrazine, etc. How to selectively regulate the nitrobenzene hydrogenation reaction path according to the target product to obtain aniline and other high-value chemicals is an urgent problem to be solved in the current nitrobenzene hydrogenation industry.
[0003] In order to control the hydrogenation process of nitrobenzene to selectively obtain phenylhydroxylamine or aniline, the core is the development of highly selective catalysts and catalytic systems. Currently, researchers have tried to use catalysts with different structures and metal particles such as amine-modified Pt nanowires, Ru / Al2O3, and Raney nickel, combined with hydrogen sources such as H2 and hydrazine hydrate to partially achieve effective control of the hydrogenation process of nitrobenzene, but the current synthesis schemes have the characteristics of high cost and easy production of by-products, resulting in increased energy consumption for subsequent separation. The physical barriers and rich microporous structures of coated catalysts can accurately adjust the reaction path of the nitrobenzene hydrogenation process to achieve the preparation of high value-added products such as phenylhydroxylamine and aniline. Summary of the invention
[0004] The purpose of the present invention is to provide a few-layer graphene-wrapped Ni catalyst and a preparation method thereof and to use the catalyst in catalyzing the selective hydrogenation of nitrobenzene to produce phenylhydroxylamine or aniline.
[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a few-layer graphene wrapped Ni catalyst, wherein the 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 few-layer graphene layers is 1 to 3.
[0006] Furthermore, the catalyst is prepared by using metal salt, organic amine and carbon source as raw materials through hydrothermal treatment to obtain a precursor, and the precursor is calcined in a N2 atmosphere and then treated with a sulfuric acid solution.
[0007] Furthermore, the metal salt is one or a mixture of two or more of nickel acetate, nickel nitrate, nickel sulfate and nickel chloride.
[0008] Furthermore, the organic amine is one or a mixture of two or more of ethanolamine, urea, dicyandiamide, and hexamethylenetetramine.
[0009] Furthermore, 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] A method for preparing a few-layer graphene-wrapped Ni catalyst comprises the following steps:
[0012] (1) Weigh metal salt, organic amine and carbon source separately in deionized water and stir to dissolve;
[0013] (2) placing the obtained solution in a polytetrafluoroethylene hydrothermal autoclave, sealing it and placing it in an oven for hydrothermal treatment. After the hydrothermal reaction is completed, centrifugally separating the obtained solid product and placing it in an oven for drying;
[0014] (3) calcining the dried solid product in a N2 atmosphere;
[0015] (4) The calcined sample was treated with a sulfuric acid solution, washed with deionized water and anhydrous ethanol, and then dried to obtain a few-layer graphene-wrapped Ni catalyst.
[0016] Furthermore, the reaction conditions of the hydrothermal treatment in step (2) are 100-180°C for 2.0-24.0 h; and the calcination conditions in step (2) are heating at 3.0-5.0°C / min to 400-800°C and maintaining for 2.0-8.0 h.
[0017] Furthermore, in step (3), the concentration of the sulfuric acid solution is 0.1-2.0 M, the temperature is 25-80 °C, and the treatment time is 2.0-24.0 h.
[0018] A few-layer graphene-wrapped Ni catalyst is used in catalyzing the hydrogenation of nitrobenzene to produce phenylhydroxylamine or aniline.
[0019] The specific steps for catalyzing the hydrogenation of nitrobenzene to prepare phenylhydroxylamine are as follows: adding a few-layer graphene-wrapped Ni catalyst, nitrobenzene, and a solvent (one or a mixture of two or more of water, methanol, ethanol, isopropanol, and tetrahydrofuran) to a polytetrafluoroethylene liner in a mass ratio of (0.1-0.3): (1-5): (10-20), ultrasonically mixing evenly, and then placing in a reactor and sealing. After replacing the air in the reactor with hydrogen (0.1-6.0 MPa), the temperature is raised to the reaction temperature (25-150 ° C) and the reaction is carried out for 0.5-10.0 h.
[0020] The specific steps for catalyzing the hydrogenation of nitrobenzene to produce aniline are as follows: add the Ni catalyst wrapped with few-layer graphene, nitrobenzene, and solvent (1.0 mL water and 4.0 mL ethanol) in a mass ratio of (0.1-0.3): (1-5): (10-20) to the polytetrafluoroethylene liner, mix evenly with ultrasound, and then put into a reactor and seal it. After replacing the air in the reactor with hydrogen (0.1-6.0 MPa), heat it to the reaction temperature (25-150 °C) and react for 0.5-10.0 h.
[0021] The few-layer graphene-wrapped Ni catalyst of the present invention has a simple synthesis route and cheap and readily available raw materials. 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 phenylhydroxylamine and aniline. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 XRD spectra of the few-layer graphene-wrapped Ni catalysts obtained in Examples 1 to 4 of the present invention.
[0023] Figure 2 Transmission electron microscope photographs of the few-layer graphene-wrapped Ni catalysts prepared in Examples 1 to 4 of the present invention.
[0024] Figure 3 These are high-resolution transmission electron microscopy photographs of the few-layer graphene-wrapped Ni catalysts obtained in Examples 1 to 4 of the present invention.
[0025] Figure 4 This is a photograph of a Ni catalyst wrapped in a few-layer graphene obtained by using a magnet to separate the catalyst in Specific Example 2 of the present invention.
[0026] Figure 5 The figure is a schematic diagram of the process of hydrogenating nitrobenzene to produce phenylhydroxylamine or aniline. DETAILED DESCRIPTION
[0027] 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.
[0028] 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.
[0029] Example 1
[0030] This embodiment is a method for preparing a few-layer graphene-wrapped Ni catalyst, which specifically includes the following steps.
[0031] (1) Take 0.5 mmol nickel acetate, 0.5 mmol nickel nitrate, 0.5 mmol ethanolamine, 1.0 mmol furfural and 1.5 mmol furfuryl alcohol in 60 mL deionized water and stir to dissolve.
[0032] (2) The obtained solution was placed in a polytetrafluoroethylene hydrothermal autoclave, sealed, and placed in a 180°C oven for hydrothermal treatment for 18.0 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.
[0033] (3) The dried solid product obtained in (2) was placed in a N2 atmosphere, heated to 400°C at 3.0°C / min, and maintained for 8.0 h.
[0034] (4) The calcined sample was treated with 0.1 M sulfuric 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-2.5 catalyst.
[0035] Example 2
[0036] This embodiment is a method for preparing a few-layer graphene-wrapped Ni catalyst, which specifically includes the following steps.
[0037] (1) Take 1.0 mmol nickel sulfate, 1.0 mmol urea, 2.0 mmol glycerol and 1.5 mmol glucose in 60 mL deionized water and stir to dissolve.
[0038] (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.
[0039] (3) The dried solid product obtained in (1) was placed in a N2 atmosphere, heated to 500°C at 4.0°C / min, and maintained for 6.0 h.
[0040] (4) The calcined sample was treated with 0.5 M sulfuric acid at 50 °C for 18.0 h, and finally washed with deionized water and anhydrous ethanol and dried at 80 °C to obtain the Ni@FLG-3.5 catalyst.
[0041] Example 3
[0042] This embodiment is a method for preparing a few-layer graphene-wrapped Ni catalyst, which specifically includes the following steps.
[0043] (1) Weigh 1.0 mmol nickel acetate, 1.5 mmol urea, 2.0 mmol dicyandiamide, and 2.5 mmol fructose respectively into 60 mL deionized water and stir to dissolve.
[0044] (2) The obtained solution was placed in a polytetrafluoroethylene hydrothermal autoclave, sealed, and placed in a 170 °C oven for hydrothermal treatment for 10.0 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.
[0045] (3) The dried solid product obtained in (1) was placed in a N2 atmosphere, heated to 600°C at 5.0°C / min, and maintained for 4.0 h.
[0046] (4) The calcined sample was treated with 1.5 M sulfuric acid at 60 °C for 10.0 h, and finally washed with deionized water and anhydrous ethanol and dried at 80 °C to obtain the Ni@FLG-4.5 catalyst.
[0047] Example 4
[0048] This embodiment is a method for preparing a few-layer graphene-wrapped Ni catalyst, which specifically includes the following steps.
[0049] (1) Weigh 0.5 mmol nickel chloride, 0.5 mmol nickel nitrate, 2.0 mmol hexamethylenetetramine and 5.5 mmol lactose respectively into 60 mL deionized water and stir to dissolve.
[0050] (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 12.0 h.
[0051] (3) The dried solid product obtained in (1) was placed in a N2 atmosphere, heated to 800°C at 5.0°C / min, and maintained for 2.0 h.
[0052] (4) The calcined sample was treated with 2.0 M sulfuric 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-5.5 catalyst.
[0053] Figure 1 XRD patterns of the catalysts Ni@FLG-2.5, Ni@FLG-3.5, Ni@FLG-4.5 and Ni@FLG-5.5 prepared in Examples 1 to 4. It can be seen from the figure that the four catalysts all have a broad peak at about 26°, indicating that there is a graphite carbon structure in the catalyst. The diffraction peaks of 44.5°, 51.9° and 76.8° indicate that the catalyst still has Ni after strong acid washing, and Ni is in a metallic state.
[0054] Figure 2 Transmission electron microscope photos of the catalysts Ni@FLG-2.5, Ni@FLG-3.5, Ni@FLG-4.5, and Ni@FLG-5.5 prepared in Examples 1 to 4. 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.
[0055] Figure 3 High-resolution transmission electron microscopy photos of the catalysts Ni@FLG-2.5, Ni@FLG-3.5, Ni@FLG-4.5, and Ni@FLG-5.5 prepared in Examples 1 to 4. From the photos, it can be seen that the Ni in the four catalysts is in the state of nanoparticles, with a size ranging from 1 to 50 nanometers, and is wrapped by few-layer graphene, and the number of layers of the few-layer graphene is 1 to 3.
[0056] Figure 4 This is a photograph of a few-layer graphene-wrapped Ni catalyst prepared in Specific Example 2 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.
[0057] Example 5
[0058] This example is to use a few-layer graphene wrapped Ni catalyst to catalyze the hydrogenation of nitrobenzene to produce phenylhydroxylamine ( Figure 5 ), specifically including the following steps.
[0059] The few-layer graphene-wrapped Ni catalyst (Ni@FLG-2.5, Ni@FLG-3.5, Ni@FLG-4.5, Ni@FLG-5.5, 10 mg), nitrobenzene (1.0 mmol), and solvent (water, methanol, ethanol, isopropanol, tetrahydrofuran, one or a mixture of two or more, the amount is 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 MPa), the temperature was raised to the reaction temperature (25 ℃) 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 shows the catalytic activity of the few-layer graphene-wrapped Ni catalyst and the effect of different solvents on the reaction.
[0060] Table 1
[0061]
[0062] As shown in Table 1, using 10 mg Ni@FLG-3.5 as the catalyst, 1.0 mmol of nitrobenzene, 1.0 mL of water and 4.0 mL of ethanol as the solvent, and reacting for 2.0 h at 25 °C and 0.1 MPa hydrogen pressure, the nitrobenzene conversion rate can reach 100%, and the selectivity for phenylhydroxylamine can reach 99.5%.
[0063] Example 6
[0064] This embodiment is a cyclic stability test of catalyzing nitrobenzene hydrogenation to phenylhydroxylamine using a few-layer graphene-wrapped Ni catalyst (Ni@FLG-3.5), which specifically includes the following steps.
[0065] 10 mg of Ni catalyst (Ni@FLG-3.5) wrapped with few-layer graphene, nitrobenzene (1.0 mmol), 1.0 mL of water and 4.0 mL of ethanol were added to 50 mL of polytetrafluoroethylene liner, ultrasonically mixed and sealed in a reactor. After replacing the air in the reactor with hydrogen (0.1 MPa), the temperature was raised to the reaction temperature (25 °C) and the reaction was continued for 2.0 h. After the reaction, the catalyst was separated by a magnet and washed three times with ethanol before being 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 phenylhydroxylamine catalyzed by Ni catalyst (Ni@FLG-3.5) wrapped with few-layer graphene.
[0066] Table 2
[0067]
[0068] As shown in Table 2, Ni@FLG-3.5 exhibits excellent catalytic activity and cyclic stability in the catalytic hydrogenation of nitrobenzene to produce phenylhydroxylamine. It has not been deactivated after ten cycles, and the selectivity for phenylhydroxylamine is maintained at >99.3%.
[0069] Example 7
[0070] This example is to use a few-layer graphene wrapped Ni catalyst to catalyze the hydrogenation of nitrobenzene to produce aniline ( Figure 5 ), specifically including the following steps.
[0071] 10 mg of Ni catalyst (Ni@FLG-3.5) wrapped with few-layer graphene, nitrobenzene (1.0 mmol), and solvent (1.0 mL of water and 4.0 mL of ethanol) were added to 50 mL of polytetrafluoroethylene liner, mixed evenly by ultrasonication, and then placed in a reactor and sealed. After replacing the air in the reactor with hydrogen (0.1~2.0 MPa), the temperature was raised to the reaction temperature (25~50 ℃) and the reaction was carried out for 2.0~3.0 h. After the reaction, the catalyst was separated by a magnet, and the product was analyzed by high performance liquid chromatography. Table 3 shows the hydrogenation of nitrobenzene to aniline catalyzed by Ni catalyst (Ni@FLG-3.5) wrapped with few-layer graphene and the effects of different hydrogen pressures, reaction temperatures and reaction times on the reaction.
[0072] Table 3
[0073]
[0074] As shown in Table 3, using 10 mg Ni@FLG-3.5 as the catalyst, 1.0 mmol nitrobenzene, 1.0 mL water and 4.0 mL ethanol as the solvent, and reacting for 3.0 h at 50 °C and 2.0 MPa hydrogen pressure, the nitrobenzene conversion rate can reach 100% and the selectivity of aniline can reach 100%.
[0075] Example 8
[0076] This embodiment is a cyclic stability test of catalyzing nitrobenzene hydrogenation to aniline using a few-layer graphene-wrapped Ni catalyst (Ni@FLG-3.5), which specifically includes the following steps.
[0077] 10 mg of Ni catalyst (Ni@FLG-3.5) wrapped with few-layer graphene, nitrobenzene (0.5 mmol), 1.0 mL of water and 4.0 mL of ethanol were added to 50 mL of polytetrafluoroethylene liner, ultrasonically mixed and sealed in a reactor. After replacing the air in the reactor with hydrogen (2.0 MPa), the temperature was raised to the reaction temperature (50 ℃) and the reaction was continued for 3.0 h. After the reaction, the catalyst was separated by a magnet, washed with ethanol three times and then directly used for the cycle test. The product was analyzed by high performance liquid chromatography. Table 4 shows the cycle stability of nitrobenzene hydrogenation to aniline catalyzed by Ni catalyst (Ni@FLG-3.5) wrapped with few-layer graphene.
[0078] Table 4
[0079]
[0080] As shown in Table 4, Ni@FLG-3.5 also exhibits excellent catalytic activity and cyclic stability in the catalytic hydrogenation of nitrobenzene to aniline, and no deactivation occurs after ten cycles.
[0081] 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 few-layer graphene-wrapped Ni catalyst, characterized in that: The 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 layers of the few-layer graphene is 1 to 3 layers.
2. The few-layer graphene-wrapped Ni catalyst according to claim 1, characterized in that: The catalyst is prepared by using metal salt, organic amine and carbon source as raw materials, and then hydrothermally treating the precursor to obtain the precursor, calcining the precursor in a N2 atmosphere and then treating the precursor with a sulfuric acid solution.
3. The few-layer graphene-wrapped Ni catalyst according to claim 2, 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.
4. The few-layer graphene-wrapped Ni catalyst according to claim 2, characterized in that: The organic amine is one or a mixture of two or more of ethanolamine, urea, dicyandiamide and hexamethylenetetramine.
5. The few-layer graphene-wrapped Ni catalyst according to claim 2, characterized in that: The carbon source is one or a mixture of two or more of furfural, furfuryl alcohol, glycerol, glucose, fructose and lactose.
6. The few-layer graphene-wrapped Ni catalyst according to claim 2, 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).
7. A method for preparing a few-layer graphene-wrapped Ni catalyst according to any one of claims 1 to 6, characterized in that The following steps are involved: (1) Weigh metal salt, organic amine and carbon source separately in deionized water and stir to dissolve; (2) placing the obtained solution in a polytetrafluoroethylene hydrothermal autoclave, sealing it and placing it in an oven for hydrothermal treatment. After the hydrothermal reaction is completed, centrifugally separating the obtained solid product and placing it in an oven for drying; (3) calcining the dried solid product in a N2 atmosphere; (4) The calcined sample was treated with a sulfuric acid solution, washed with deionized water and anhydrous ethanol, and then dried to obtain a few-layer graphene-wrapped Ni catalyst.
8. The preparation method according to claim 7, characterized in that: The reaction conditions of the hydrothermal treatment in step (2) are 100-180°C for 2.0-24.0 h; the calcination conditions in step (2) are heating at 3.0-5.0°C / min to 400-800°C and maintaining for 2.0-8.0 h.
9. The preparation method according to claim 7, characterized in that: In step (3), the concentration of the sulfuric acid solution is 0.1-2.0 M, the temperature is 25-80 °C, and the treatment time is 2.0-24.0 h.
10. Use of the few-layer graphene-wrapped Ni catalyst according to any one of claims 1 to 6 in catalyzing the hydrogenation of nitrobenzene to produce phenylhydroxylamine or aniline.