Preparation method and application of nitro compound hydrogenation catalyst
By preparing a nickel-cobalt bimetallic catalyst for the hydrogenation reaction of nitrobenzene, the problems of insufficient catalytic activity and selectivity in the existing technology were solved, and efficient conversion of nitrobenzene and aniline yield were achieved, which is suitable for industrial application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QUZHOU RES INST OF ZHEJIANG UNIV
- Filing Date
- 2025-01-27
- Publication Date
- 2026-07-03
AI Technical Summary
Existing supported single-metal catalysts exhibit low catalytic activity and poor selectivity when used for the hydrogenation of nitro compounds, resulting in low yields of aniline compounds and making them unsuitable for large-scale industrial production.
A nickel-cobalt bimetallic catalyst was prepared and supported on an oxide support for the hydrogenation reaction of nitrobenzene. Combined with a reaction process under specific conditions, the catalytic activity and selectivity were improved.
The conversion rate of nitrobenzene and the yield of aniline were improved at lower reaction temperatures and pressures, making it suitable for industrial production, and the catalyst can be reused.
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Figure CN119972077B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst technology, specifically to a method for preparing and applying a hydrogenation catalyst for nitro compounds. Background Technology
[0002] Aniline compounds are fine chemicals widely used in pharmaceutical synthesis, pesticides, dyes, and electronic materials. Currently, most chemical companies both domestically and internationally use the catalytic hydrogenation reduction method of nitro compounds to prepare aromatic amines. Improving and developing the hydrogenation catalyst itself to obtain catalysts with high activity, good stability, long service life, and suitable particle size is also a core technology of catalytic hydrogenation. The production of aniline both domestically and internationally generally uses Co-SiO2 catalysts. This catalyst can selectively reduce the nitro group on the benzene ring to an amino group without affecting the benzene ring, but the required reaction temperature and pressure are relatively high.
[0003] Supported catalysts are metal catalysts supported on suitable supports, such as diatomaceous earth, silica gel, activated alumina, zeolite molecular sieves, titanium dioxide, and activated carbon. On the one hand, the catalytic active sites of the catalyst can be controlled by adjusting the size, morphology, composition, and coordination environment of the metal through the support; on the other hand, changing the support can also affect the adsorption of reactants. Due to their low cost and high activity, they are widely used in various hydrogenation reactions, such as the hydrogenation of natural oils and fats, and the hydrogenation of nitrobenzene to aniline. Patent CN114452980A discloses a platinum-supported Ni / Mg / Fe layered double hydroxide catalyst for the catalytic hydrogenation of nitro compounds to aniline. Patent CN115301261A discloses a nickel-supported boron-doped silicon carbide catalyst for the hydrogenation of nitrobenzene. Patent CN103288651B discloses a nickel-supported bentonite catalyst for the catalytic hydrogenation of nitrobenzene to aniline.
[0004] Current inventions utilize supported monometallic catalysts to achieve catalytic hydrogenation to aniline. However, the yield of aniline is low, and the selectivity of catalytic hydrogenation is poor, which is not conducive to large-scale industrial production. Therefore, designing and developing low-cost, highly active, and stable supported bimetallic catalysts is a crucial step in the development of hydrogenation catalysts for nitro compounds and is essential for realizing large-scale industrial production of aromatic amines. Summary of the Invention
[0005] The technical problem to be solved by this invention is to provide a method for preparing and applying a catalyst for the hydrogenation of nitro compounds. This invention first prepares a catalyst composed of nickel salt, cobalt salt, and a support, and uses it in the hydrogenation reaction of nitrobenzene. Through nickel-cobalt bimetallic catalysis, the cost of the selective hydrogenation catalyst for nitrobenzene is reduced while ensuring catalytic activity.
[0006] This invention provides a method for preparing the above-mentioned supported catalyst, the method comprising the following steps:
[0007] 1) Mix the aqueous solutions of nickel nitrate hexahydrate and cobalt nitrate with the aqueous solution of oxide support in a three-necked flask; then add alkaline solution dropwise and stir continuously to adjust the pH of the mixture to 10-11, and continue stirring at 50°C for 2 hours; filter to obtain the impregnated support and vacuum dry at 50°C for 10 hours to remove water.
[0008] 2) The impregnated support is placed in a muffle furnace and calcined at 400-600℃ for 2 hours. It is then transferred to a tube furnace and reduced at 300-500℃ for 3 hours under a 10% H2 / 90% Ar atmosphere. Finally, it is cooled to room temperature under a nitrogen atmosphere to obtain the finished supported nickel-cobalt catalyst.
[0009] The nickel content is 20% to 35% of the oxide support weight, and the cobalt content is 1% to 7% of the oxide support weight, preferably 25% nickel and 5% cobalt.
[0010] The support includes one of SiO2, TiO2, γ-Al2O3, CeO2, MgO, MnO2, and Fe2O3, preferably γ-Al2O3.
[0011] The alkaline solution is specifically prepared by dissolving NaOH in deionized water, and the concentration of the alkaline solution is 10 wt%.
[0012] This invention also provides the application of the above-mentioned supported nickel-cobalt catalyst in the hydrogenation reaction of nitro compounds, including:
[0013] The activated catalyst, along with the raw material nitrobenzene and the solvent methanol, were added to a high-pressure reactor. The mass ratio of the activated supported catalyst to the raw material nitrobenzene was 5 wt%. The interior of the high-pressure reactor was purged with hydrogen gas, and then the reaction was carried out at a reaction temperature of 110°C and a reaction pressure of 1.0 MPa for 2 hours. After the reaction was completed, the high-pressure reactor was opened, the catalyst was removed by filtration, and the filtrate was collected to obtain the product anilinebenzene.
[0014] The present invention has the following advantages over the prior art:
[0015] (1) Thanks to the synergistic effect of nickel-cobalt bimetals, the reaction of preparing aromatic amine compounds from nitro compounds described in this invention does not require high reaction temperature and reaction pressure, is environmentally friendly, has high raw material conversion rate, and high product yield.
[0016] (2) The present invention prepares a supported catalyst, which is applied to the reaction of nitro compounds to prepare aromatic amine compounds. The reaction conditions are mild and easy to industrialize.
[0017] (3) The supported catalyst of the present invention has the characteristics of simple preparation method and reusability. Attached Figure Description
[0018] Figure 1 .Ni 25 XRD pattern of Co5 / Al2O3 catalyst. Detailed Implementation
[0019] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.
[0020] Example 1: The synthesis reaction method of aniline and the preparation of its catalyst, which are carried out in sequence as follows:
[0021] 1) Catalyst preparation:
[0022] ① Dissolve 9.86g of nickel nitrate hexahydrate and 0.493g of cobalt nitrate hexahydrate in deionized water to prepare a solution. Add 10g of γ-Al2O3 deionized water solution and mix. Add 10% NaOH solution dropwise and stir continuously to adjust the pH of the mixture to 10-11. Continue stirring at 50℃ for 2 hours. Filter to obtain the impregnated carrier and vacuum dry at 50℃ for 10 hours to remove water.
[0023] ② After grinding the dried precursor, place it in a muffle furnace and calcine it at 400℃ for 2 hours at a heating rate of 5℃ / min. Sift the 80-100 mesh particles for later use. Place the prepared supported catalyst in a tube furnace and continuously pass a 10% H2 / 90% Ar mixture through it at a flow rate of 200 mL / min. Heat the mixture to 400℃ at a heating rate of 5℃ / min and maintain the temperature for 5 hours. Then, cool it to room temperature under a nitrogen atmosphere to obtain the finished supported nickel-cobalt catalyst, which is stored in a reagent bag for later use.
[0024] In this supported catalyst, nickel accounts for 20% of the total weight of the supported catalyst, and cobalt accounts for 1% of the total weight of the supported catalyst.
[0025] 2) Feeding and discharging:
[0026] ① Weigh 10g of raw material nitrobenzene, 100mL of solvent methanol and 500mg of activated catalyst (catalyst to raw material mass ratio is 5%) and pour them into a 500mL reaction vessel, then combine the vessels.
[0027] ② The inner cavity of the autoclave is replaced with hydrogen multiple times, and then the reaction is carried out at a reaction temperature of 110℃ and a hydrogen pressure of 1.0 MPa for 2 hours.
[0028] ③ After the reaction is complete, open the autoclave.
[0029] The reaction solution is filtered. The filtrate is collected to obtain the product.
[0030] ④ The conversion rate of nitrobenzene and the selectivity of aniline were calculated to be 90% and 87%, respectively.
[0031] Example 2
[0032] In this embodiment, except for the addition of 12.33 g of nickel nitrate hexahydrate, everything else was the same as in Example 1. The resulting material was a supported nickel-cobalt catalyst, with nickel accounting for 25% of the total weight of the supported catalyst and cobalt accounting for 1% of the total weight of the supported catalyst. The catalytic performance test was the same as in Example 1, with a conversion rate and selectivity of 93% and 88% for the selective hydrogenation reaction of nitrobenzene, respectively.
[0033] Example 3
[0034] In this embodiment, except that the amount of nickel nitrate hexahydrate added was 14.80 g, everything else was the same as in Example 1. The resulting material was a supported nickel-cobalt catalyst, with nickel accounting for 30% of the total weight of the supported catalyst and cobalt accounting for 1% of the total weight of the supported catalyst. The catalytic performance test was the same as in Example 1, with a conversion rate and selectivity of 88% and 81% for the selective hydrogenation reaction of nitrobenzene, respectively.
[0035] Example 4
[0036] In this embodiment, except for the addition of 17.26 g of nickel nitrate hexahydrate, everything else was the same as in Example 1. The resulting material was a supported nickel-cobalt catalyst, with nickel accounting for 35% of the total weight of the supported catalyst and cobalt accounting for 1% of the total weight of the supported catalyst. The catalytic performance test was the same as in Example 1, with a conversion rate and selectivity of 82% and 76% for the selective hydrogenation reaction of nitrobenzene, respectively.
[0037] Example 5
[0038] In this embodiment, except for the addition of 1.48 g of cobalt nitrate hexahydrate, everything else is the same as in Example 2. The resulting material is a supported nickel-cobalt catalyst, with nickel accounting for 25% of the total weight of the supported catalyst and cobalt accounting for 3% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, with a conversion rate and selectivity of 90% and 89% for the selective hydrogenation reaction of nitrobenzene, respectively.
[0039] Example 6
[0040] In this embodiment, except for the addition of 2.47 g of cobalt nitrate hexahydrate, everything else is the same as in Example 2. The obtained material is a supported nickel-cobalt catalyst, with nickel accounting for 25% of the total weight of the supported catalyst and cobalt accounting for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, with the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene being 99% and 99%, respectively.
[0041] Example 7
[0042] In this embodiment, except that the amount of cobalt nitrate hexahydrate added was 3.45 g, everything else was the same as in Example 2. The resulting material was a supported nickel-cobalt catalyst, with nickel accounting for 25% of the total weight of the supported catalyst and cobalt accounting for 7% of the total weight of the supported catalyst. The catalytic performance test was the same as in Example 1, with a conversion rate and selectivity of 93% and 89% for the selective hydrogenation reaction of nitrobenzene, respectively.
[0043] The process parameters and reaction results are shown in Table 1.
[0044] Table 1 Data from Examples 1 to 7
[0045] Example Nickel-cobalt bimetallic catalyst Nitrobenzene conversion rate (%) Aniline selectivity (%) 1 <![CDATA[Ni 20 Co1 / Al2O3]]> 90 87 2 <![CDATA[Ni 25 Co1 / Al2O3]]> 93 88 3 <![CDATA[Ni 30 What 1 / Al2O3]]> 88 81 4 <![CDATA[Ni 35 Co1 / Al2O3]]> 82 76 5 <![CDATA[Ni 25 Co3 / Al2O3]]> 90 89 6 <![CDATA[Ni 25 Co5 / Al2O3]]> 99 99 7 <![CDATA[Ni 25 What 7 / Al2O3]]> 93 89
[0046] Example 8
[0047] In this embodiment, except for the addition of 10g CeO2 to replace γ-Al2O3, everything else is the same as in Example 6. The resulting material is a supported nickel-cobalt catalyst, with nickel accounting for 25% of the total weight of the supported catalyst and cobalt accounting for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, with a conversion rate and selectivity of 98% and 83% for the selective hydrogenation reaction of nitrobenzene, respectively.
[0048] Example 9
[0049] In this embodiment, except for the addition of 10g MgO to replace γ-Al2O3, everything else is the same as in Example 6. The resulting material is a supported nickel-cobalt catalyst, with nickel accounting for 25% of the total weight of the supported catalyst and cobalt accounting for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, with a conversion rate and selectivity of 95% and 73% for the selective hydrogenation reaction of nitrobenzene, respectively.
[0050] Example 10
[0051] In this embodiment, except for the addition of 10g MnO2 to replace γ-Al2O3, everything else is the same as in Example 6. The resulting material is a supported nickel-cobalt catalyst, with nickel accounting for 25% of the total weight of the supported catalyst and cobalt accounting for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, with the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene being 90% and 84%, respectively.
[0052] Example 11
[0053] In this embodiment, except for the addition of 10g Fe2O3 to replace γ-Al2O3, everything else is the same as in Example 6. The resulting material is a supported nickel-cobalt catalyst, with nickel accounting for 25% of the total weight of the supported catalyst and cobalt accounting for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, with a conversion rate and selectivity of 84% and 72% for the selective hydrogenation reaction of nitrobenzene, respectively.
[0054] Example 12
[0055] In this embodiment, except for the addition of 10g TiO2 to replace γ-Al2O3, everything else is the same as in Example 6. The resulting material is a supported nickel-cobalt catalyst, with nickel accounting for 25% of the total weight of the supported catalyst and cobalt accounting for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, with a conversion rate and selectivity of 85% and 72% for the selective hydrogenation reaction of nitrobenzene, respectively.
[0056] Example 13
[0057] In this embodiment, except for the addition of 10g SiO2 to replace γ-Al2O3, everything else is the same as in Example 6. The resulting material is a supported nickel-cobalt catalyst, with nickel accounting for 25% of the total weight of the supported catalyst and cobalt accounting for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, with the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene being 93% and 85%, respectively.
[0058] Table 2 Data from Examples 8 to 13
[0059] Example Catalyst support types Nitrobenzene conversion rate (%) Aniline selectivity (%) 8 <![CDATA[CeO2]]> 98 83 9 MgO 95 73 10 <![CDATA[MnO2]]> 90 84 11 <![CDATA[Fe2O3]]> 84 72 12 <![CDATA[TiO2]]> 85 72 13 <![CDATA[SiO2]]> 93 85
[0060] Finally, it should be noted that the above examples are merely some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.
Claims
1. Use of a nitro compound hydrogenation catalyst for a nitrobenzene hydrogenation reaction, characterized in that: The preparation method of the nitro compound hydrogenation catalyst includes the following steps: 1) Mix the aqueous solutions of nickel nitrate hexahydrate and cobalt nitrate with the aqueous solution of the oxide support; then add an alkaline solution dropwise, stir and mix, adjust the pH of the mixture to 10-11, and continue stirring at 50°C for 2 hours; filter and dry to obtain the impregnated support; 2) The impregnated support is placed in a muffle furnace and calcined at 400-600℃ for 2 hours, then reduced at 300-500℃ for 3 hours under a 10%H2 / 90%Ar atmosphere, and then cooled to room temperature under a nitrogen atmosphere to obtain the finished supported nickel-cobalt catalyst. In step 2), the weight of nickel is 25% of the weight of the oxide support; the weight of cobalt is 5% of the weight of the oxide support; and the oxide support is γ-Al2O3.
2. Use according to claim 1, characterized in that, Specifically, the following steps are included: 1) Mix the aqueous solutions of nickel nitrate hexahydrate and cobalt nitrate with the aqueous solution of the oxide support in a three-necked flask; then add an alkaline solution dropwise and stir continuously to adjust the pH of the mixture to 10-11, and continue stirring at 50°C for 2 hours; filter to obtain the impregnated support and vacuum dry at 50°C for 10 hours to remove water; 2) The impregnated support is placed in a muffle furnace and calcined at 400-600℃ for 2 hours. It is then transferred to a tube furnace and reduced at 300-500℃ for 3 hours under a 10%H2 / 90%Ar atmosphere. Finally, it is cooled to room temperature under a nitrogen atmosphere to obtain the finished supported nickel-cobalt catalyst.
3. Use according to claim 1 or 2, characterized in that: Step 1) The alkaline solution is prepared by dissolving NaOH in deionized water, and the concentration of the alkaline solution is 10 wt%.
4. Use according to claim 1, characterized in that: The application method is as follows: the activated catalyst for hydrogenation of nitro compounds, the raw material nitrobenzene, and the solvent methanol are added to a high-pressure reactor. The inner cavity of the high-pressure reactor is replaced with hydrogen. Then, the reaction is carried out at a reaction temperature of 110°C and a reaction pressure of 1.0 MPa for 2 hours. After the reaction is completed, the high-pressure reactor is opened, the catalyst is removed by filtration, and the filtrate is collected to obtain the product aniline.
5. Use according to claim 4, characterized in that: The activated catalyst for hydrogenating nitro compounds has a mass ratio of 5 wt% to the raw material nitrobenzene.