Preparation method and application of nitro compound hydrogenation catalyst

Abstract

The invention relates to the technical field of catalysts, in particular to a preparation method and application of a nitro compound hydrogenation catalyst. According to the invention, the catalyst prepared from the nickel salt, the cobalt salt and the carrier is firstly prepared and is used in the hydrogenation reaction of nitrobenzene, and the cost of the nitrobenzene selective hydrogenation catalyst is reduced while the catalytic activity is ensured in a nickel-cobalt bimetallic catalysis mode. The reaction for preparing the arylamine compound from the nitro compound does not need higher reaction temperature and reaction pressure, and is environment-friendly, high in raw material conversion rate and high in product yield. The prepared supported catalyst is applied to a reaction for preparing an arylamine compound from a nitro compound, the reaction condition is mild, and industrial production is easy; the supported catalyst provided by the invention has the characteristics of simple preparation method, reusability and the like.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a preparation method and application of a nitro compound hydrogenation catalyst. Background Art

[0002] Aniline compounds are fine chemicals widely used in drug synthesis, pesticides, fungicides, dyes and electronic materials. At present, most chemical companies at home and abroad most often use nitro compound catalytic hydrogenation reduction method to prepare aromatic amines. The improvement and development of hydrogenation catalysts themselves to obtain catalysts with high activity, good stability, long service life and suitable particle size is also the core technology of catalytic hydrogenation. The production of aniline at home and abroad generally uses Co-SiO2 catalyst, which can selectively reduce the nitro group on the benzene ring to an amine group without affecting the benzene ring, but the required reaction temperature and pressure are relatively high.

[0003] Supported catalysts are metal catalysts loaded on appropriate carriers, such as diatomaceous earth, silica gel, activated alumina, zeolite molecular sieves, titanium dioxide and activated carbon. On the one hand, the size, morphology, composition, coordination environment and other catalytic active sites of the catalyst can be regulated by the carrier. On the other hand, changing the carrier will also affect the adsorption of the reactants. Due to its low price and high activity, it is widely used in a variety of hydrogenation reactions, such as natural oil hydrogenation, nitrobenzene hydrogenation synthesis of aniline, etc. Patent CN114452980A discloses a platinum-loaded Ni / Mg / Fe hydrotalcite catalyst to achieve catalytic hydrogenation of nitro compounds to produce aniline. Patent CN115301261A discloses a catalyst of boron-doped silicon carbide loaded with nickel, which can be used for nitrobenzene hydrogenation. Patent CN103288651B discloses a reaction of catalytic hydrogenation of nitrobenzene to produce aniline using a catalyst of nickel-loaded bentonite.

[0004] The current invention is to use a supported monometallic catalyst to achieve catalytic hydrogenation to generate aniline, but the yield of aniline is low and the selectivity of catalytic hydrogenation is poor, which is not conducive to large-scale industrial production. Therefore, the design and development of low-cost, highly active, and stable supported bimetallic catalysts is a key step in the development of nitro compound hydrogenation catalysts and is crucial to the realization of large-scale industrial production of aromatic amines. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a preparation method and application of a catalyst for hydrogenation of nitro compounds. The present invention first prepares a catalyst prepared from a nickel salt, a cobalt salt and a carrier, and uses it in the hydrogenation reaction of nitrobenzene. By using a nickel-cobalt bimetallic catalysis method, the cost of the nitrobenzene selective hydrogenation catalyst is reduced while ensuring the catalytic activity.

[0006] The present 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 the oxide carrier in a three-necked flask; then dropwise add the alkaline solution, and continuously stir to adjust the pH of the mixed solution to 10-11, and continue stirring at 50°C for 2h; filter the impregnated carrier and vacuum dry it at 50°C for 10h to remove water.

[0008] 2) The impregnated carrier was placed in a muffle furnace and calcined at 400-600°C for 2h, transferred to a tubular furnace, reduced at 300-500°C for 3h in a 10% H2 / 90% Ar atmosphere, and cooled to room temperature in a nitrogen atmosphere to obtain a finished supported nickel-cobalt catalyst.

[0009] The weight of nickel is 20% to 35% of the weight of the oxide support; the weight of cobalt is 1% to 7% of the weight of the oxide support, preferably 25% by weight of nickel and 5% by weight of cobalt.

[0010] The carrier 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] The present invention also provides an application of the above-mentioned supported nickel-cobalt catalyst for hydrogenation reaction of nitro compounds, including:

[0013] The activated catalyst, raw material nitrobenzene and solvent methanol are added into an autoclave, wherein the mass ratio of the activated supported catalyst to the raw material nitrobenzene is 5wt%. The inner cavity of the autoclave is replaced with hydrogen, and 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 autoclave is opened, the catalyst is filtered out, and the filtrate is collected to obtain the product aniline benzene.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] (1) Benefiting from the nickel-cobalt bimetallic synergistic effect, the reaction of preparing aromatic amine compounds from nitro compounds according to the present 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 supported catalyst prepared by the present invention is applied to the reaction of preparing aromatic amine compounds from nitro compounds, and 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 .Ni 25 XRD spectrum of Co5 / Al2O3 catalyst. DETAILED DESCRIPTION

[0019] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or several specific embodiments of the present invention, and does not strictly limit the scope of protection of the specific claims of the present invention.

[0020] Embodiment 1, the synthetic reaction method of aniline and the preparation of catalyst thereof, carry out the following steps in sequence:

[0021] 1) Preparation of catalyst:

[0022] ①. Dissolve 9.86g nickel nitrate hexahydrate and 0.493g cobalt nitrate hexahydrate in deionized water to prepare a solution, add 10g of γ-Al2O3 in deionized water and mix, dropwise add 10% NaOH solution by mass, and stir continuously to adjust the pH of the mixture to 10-11, and continue stirring at 50°C for 2h; filter the impregnated carrier and vacuum dry it at 50°C for 10h to remove water.

[0023] ②. Grind the dried precursor and place it in a muffle furnace and heat it to 400℃ at a rate of 5℃ / min for 2h, and sieve out 80-100 mesh particles for later use. Place the supported catalyst prepared above in a tubular furnace, and continuously introduce a 10% H2 / 90% Ar mixed gas at a flow rate of 200mL / min, heat it to 400℃ at a rate of 5℃ / min and maintain it for 5h, and cool it to room temperature in a nitrogen atmosphere to obtain the finished supported nickel-cobalt catalyst, which is stored in a reagent bag for later use.

[0024] In the 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 10 g of raw material nitrobenzene, 100 mL of solvent methanol and 500 mg of activated catalyst (the mass ratio of catalyst to raw material is 5%) and pour them into a 500 mL reaction kettle, and close the kettle.

[0027] ②. Use hydrogen to replace the gas in the autoclave multiple times, and then react for 2 hours at a reaction temperature of 110°C and a hydrogen pressure of 1.0 MPa.

[0028] ③. After the reaction is completed, open the autoclave.

[0029] The reaction solution is filtered and 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 that the amount of nickel nitrate hexahydrate added is 12.33 g, the rest is the same as in Example 1, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 25% of the total weight of the supported catalyst and cobalt accounts for 1% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 93% and 88% respectively.

[0033] Example 3

[0034] In this embodiment, except that the amount of nickel nitrate hexahydrate added is 14.80g, the rest is the same as in Example 1, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 30% of the total weight of the supported catalyst and cobalt accounts for 1% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 88% and 81% respectively.

[0035] Example 4

[0036] In this embodiment, except that the amount of nickel nitrate hexahydrate added is 17.26g, the rest is the same as in Example 1, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 35% of the total weight of the supported catalyst and cobalt accounts for 1% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 82% and 76% respectively.

[0037] Example 5

[0038] In this embodiment, except that the amount of cobalt nitrate hexahydrate added is 1.48g, the rest is the same as in Example 2, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 25% of the total weight of the supported catalyst and cobalt accounts for 3% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 90% and 89% respectively.

[0039] Example 6

[0040] In this embodiment, except that the amount of cobalt nitrate hexahydrate added is 2.47g, the rest is the same as in Example 2, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 25% of the total weight of the supported catalyst and cobalt accounts for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 99% and 99% respectively.

[0041] Example 7

[0042] In this embodiment, except that the amount of cobalt nitrate hexahydrate added is 3.45g, the rest is the same as in Example 2, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 25% of the total weight of the supported catalyst and cobalt accounts for 7% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 93% and 89% respectively.

[0043] The process parameters and reaction results are shown in Table 1.

[0044] Table 1 Data of 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 <h2 style=";text-align:left;direction:ltr"><![CDATA[Ni <h2 style=";text-align:left;direction:ltr"> 25 <h2 style=";text-align:left;direction:ltr"> Co3 / Al2O3<h2 style=";text-align:left;direction:ltr"> 90 89 6 <h2 style=";text-align:left;direction:ltr"><![CDATA[Ni <h2 style=";text-align:left;direction:ltr"> 25 <h2 style=";text-align:left;direction:ltr"> Co5 / Al2O3<h2 style=";text-align:left;direction:ltr"> 99 99 7 <![CDATA[Ni 25 What 7 / Al2O3]]> 93 89

[0046] Example 8

[0047] In this embodiment, except for adding 10g CeO2 to replace γ-Al2O3, the rest is the same as that of Example 6, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 25% of the total weight of the supported catalyst and cobalt accounts for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as that of Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 98% and 83% respectively.

[0048] Example 9

[0049] In this embodiment, except for adding 10g MgO to replace γ-Al2O3, the rest is the same as that of Example 6, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 25% of the total weight of the supported catalyst and cobalt accounts for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as that of Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 95% and 73% respectively.

[0050] Example 10

[0051] In this embodiment, except for adding 10g MnO2 to replace γ-Al2O3, the rest is the same as in Example 6, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 25% of the total weight of the supported catalyst and cobalt accounts for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 90% and 84% respectively.

[0052] Embodiment 11

[0053] In this embodiment, except for adding 10g of Fe2O3 to replace γ-Al2O3, the rest is the same as that of Example 6, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 25% of the total weight of the supported catalyst and cobalt accounts for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as that of Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 84% and 72% respectively.

[0054] Example 12

[0055] In this embodiment, except for adding 10g TiO2 to replace γ-Al2O3, the rest is the same as in Example 6, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 25% of the total weight of the supported catalyst and cobalt accounts for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 85% and 72% respectively.

[0056] Embodiment 13

[0057] In this embodiment, except for adding 10g SiO2 to replace γ-Al2O3, the rest is the same as in Example 6, and the obtained material is a supported nickel-cobalt catalyst, in which nickel accounts for 25% of the total weight of the supported catalyst and cobalt accounts for 5% of the total weight of the supported catalyst. The catalytic performance test is the same as in Example 1, and the conversion rate and selectivity of the selective hydrogenation reaction of nitrobenzene are 93% and 85%, respectively.

[0058] Table 2 Data of Examples 8 to 13

[0059] Example Catalyst carrier type 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 only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A method for preparing a nitro compound hydrogenation catalyst, comprising the following steps: 1) Mixing an aqueous solution of nickel nitrate hexahydrate and cobalt nitrate with an aqueous solution of an oxide support; then dropwise adding an alkaline solution, stirring and mixing, adjusting the pH of the mixture to 10-11, and continuing stirring at 50° C. for 2 hours; filtering and drying to obtain an impregnated support; 2) The impregnated carrier was placed in a muffle furnace and calcined at 400-600° C. for 2 h, then reduced at 300-500° C. for 3 h in a 10% H2 / 90% Ar atmosphere, and cooled to room temperature in a nitrogen atmosphere to obtain a finished supported nickel-cobalt catalyst.

2. The preparation method according to claim 1, characterized in that: The specific steps include: 1) Mixing an aqueous solution of nickel nitrate hexahydrate and cobalt nitrate with an aqueous solution of an oxide support in a three-necked flask; then dropping an alkaline solution, stirring continuously to adjust the pH of the mixed solution to 10-11, and continuing stirring at 50° C. for 2 h; filtering the impregnated support and vacuum drying it at 50° C. for 10 h to remove water; 2) The impregnated carrier was placed in a muffle furnace and calcined at 400-600°C for 2h, transferred to a tubular furnace, reduced at 300-500°C for 3h in a 10% H2 / 90% Ar atmosphere, and cooled to room temperature in a nitrogen atmosphere to obtain a finished supported nickel-cobalt catalyst.

3. The preparation method according to claim 1 or 2, characterized in that: Step 1) The oxide carrier is one of SiO2, TiO2, γ-Al2O3, CeO2, MgO, MnO2, and Fe2O3.

4. The preparation method 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%.

5. The preparation method according to claim 1 or 2, characterized in that: In step 2), in the supported nickel-cobalt catalyst, the weight of nickel is 20% to 35% of the weight of the oxide support; the weight of cobalt is 1% to 7% of the weight of the oxide support.

6. The preparation method according to claim 1 or 2, characterized in that: 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; the oxide support is γ-Al2O3.

7. A catalyst for hydrogenation of nitro compounds, characterized in that: The supported nickel-cobalt catalyst prepared by the preparation method according to claim 1 or 2, wherein the weight of nickel is 20% to 35% of the weight of the oxide support; and the weight of cobalt is 1% to 7% of the weight of the oxide support.

8. Use of the nitro compound hydrogenation catalyst according to claim 7 in the hydrogenation reaction of nitrobenzene.

9. The use according to claim 8, characterized in that: The application method is as follows: adding the activated catalyst for hydrogenation of nitro compounds, raw material nitrobenzene and solvent methanol into an autoclave, replacing the gas in the inner cavity of the autoclave with hydrogen, and then reacting for 2 hours at a reaction temperature of 110°C and a reaction pressure of 1.0MPa. After the reaction is completed, opening the autoclave, filtering to remove the catalyst, and collecting the filtrate to obtain the product aniline benzene.

10. The use according to claim 9, characterized in that: The mass ratio of the activated supported catalyst to the raw material nitrobenzene is 5wt%.

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