Carbon-based catalysts, methods of making and using the same

Abstract

The present application relates to the field of catalyst preparation, and discloses a carbon-based catalyst, a preparation method and application thereof, and a selective hydrogenation method of aryl nitro compounds.The carbon-based catalyst comprises an activated carbon carrier and an active component loaded on the activated carbon carrier; the activated carbon carrier is an activated carbon carrier containing S and P; the active component contains one or more of Fe, Co, Ni and Cu; in the carbon-based catalyst, the content of the active component is 0.05-5 wt.%, the content of S is 0.005-1 wt.%, and the content of P is 0.01-3 wt.%, relative to the total weight of the carbon-based catalyst.The carbon-based catalyst of the present application exhibits excellent catalytic activity, selectivity and stability in the selective hydrogenation reaction of halogenated aryl nitro compounds, and has high practical application and promotion value due to low catalyst cost.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation, specifically to a carbon-based catalyst, its preparation method and application, and a selective hydrogenation method for aromatic nitro compounds. Background Technology

[0002] Halogenated aromatic amines are important industrial raw materials, including p-chloroaniline, neochloroaniline, m-chloroaniline, p-fluoroaniline, p-bromoaniline, and p-iodoaniline, and are important intermediates in pharmaceuticals, pesticides, fragrances, and dyes. Current production methods mainly involve the reduction of the corresponding halogenated aromatic nitro compounds, specifically including iron powder reduction, sulfite reduction, sodium sulfide reduction, and catalytic hydrogenation reduction. The iron powder reduction, sulfite reduction, and sodium sulfide reduction methods result in severe waste pollution and poor product quality. Due to their better environmental friendliness and atom economy, selective catalytic hydrogenation is a feasible and effective method for preparing halogenated aromatic amines.

[0003] Currently, catalysts for the hydrogenation preparation of haloaromatic amines mostly employ catalysts containing noble metals, such as supported catalysts of Pd, Pt, and Au, which are prepared by supporting the noble metals on supports such as activated carbon. Among them, Pd / C catalysts are the most widely studied and applied. Generally, Pd is supported on commercial activated carbon or activated carbon that has undergone further treatment with acids and alkalis, followed by calcination, reduction, and other processes. However, due to the high price of noble metal catalysts and the difficulty in recovering the noble metals, the cost of using catalysts is high. When using activated carbon as a support to prepare catalysts, the activated carbon often accounts for a certain cost, and further treatment of the activated carbon or the carbon-based catalyst after support is often required to achieve better catalytic performance. For example, CN107970967B uses hydrochloric acid and nitric acid to treat activated carbon, and then uses inorganic ammonium compounds to coordinate the Pd and Pt noble metals supported on the activated carbon, achieving better catalytic performance in the hydrogenation of chloronitrobenzene to chloroaniline. However, the pretreatment of activated carbon and the further coordination treatment of catalyst active sites increase the complexity of the preparation process, and the inorganic ammonium coordinated with noble metals is also relatively easy to be lost when the catalyst is used.

[0004] On the other hand, the hydrogenation of haloaromatic nitro compounds using catalysts such as Pd / C suffers from numerous side reactions, including dehalogenation, leading to catalyst poisoning and deactivation, as well as equipment corrosion. Current solutions involve adding dehalogenation inhibitors to suppress these side reactions, but this affects product quality and increases the need for separation between the inhibitor and the product, thus raising production costs.

[0005] Therefore, in actual production processes, highly active, highly selective, highly stable, and inexpensive selective hydrogenation catalysts for halogenated aromatic nitro compounds are still needed. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned technical problems existing in the prior art, and to provide a carbon-based catalyst, its preparation method and application, as well as a selective hydrogenation method for aromatic nitro compounds. This carbon-based catalyst exhibits excellent catalytic activity, selectivity and stability in the selective hydrogenation reaction of haloaromatic nitro compounds. At the same time, the catalyst is inexpensive and has high practical application and promotion value.

[0007] To achieve the above objectives, the present invention provides a carbon-based catalyst, the carbon-based catalyst comprising an activated carbon support and an active component supported on the activated carbon support;

[0008] The activated carbon carrier is an activated carbon carrier containing S and P;

[0009] The active component contains one or more of Fe, Co, Ni, and Cu;

[0010] In the carbon-based catalyst, the content of the active component is 0.05-5 wt.%, the content of S is 0.005-1 wt.%, and the content of P is 0.01-3 wt.%, relative to the total weight of the carbon-based catalyst.

[0011] Preferably, the catalyst has a specific surface area of ​​200-1000 m². 2 / g.

[0012] Preferably, the active component contains Co and / or Ni.

[0013] Preferably, the content of the active component is 0.1-3 wt.% relative to the total weight of the carbon-based catalyst.

[0014] Preferably, the carbon-based catalyst has an S content of 0.01-0.8 wt.% and a P content of 0.03-2 wt.%.

[0015] Preferably, the carbon-based catalyst is obtained by carbonizing a mixture of biomass carbon source, precursor of active component and pore-forming agent. The biomass carbon source is one or more of the following: fruit kernel, coconut shell, durian shell, bamboo, peanut, peanut meal, soybean, soybean meal, rice straw, rice husk, rice bran, cassava stalk and mushroom residue. Preferably, it is one or more of the following: coconut shell, peanut, peanut meal, soybean and soybean meal.

[0016] Preferably, the particle size of the mixture is Dv(90)≤500μm, and more preferably Dv(90)≤200μm.

[0017] The second aspect of the present invention provides a method for preparing a carbon-based catalyst, the method comprising: mixing a biomass carbon source, a precursor of an active component and a pore-forming agent in the presence of water, and then sequentially performing drying, carbonization treatment and acid washing.

[0018] The biomass carbon source is one or more of the following: fruit kernels, coconut shells, durian shells, bamboo, peanuts, peanut meal, soybeans, soybean meal, rice straw, rice husks, rice bran, cassava stalks, and mushroom residue.

[0019] The precursor of the active component contains one or more of Fe, Co, Ni, and Cu.

[0020] Preferably, the mass ratio of biomass carbon source, precursor of active component and pore-forming agent is 1:(0.005-1):(0.1-50), more preferably 1:(0.01-0.5):(0.5-20).

[0021] Preferably, the biomass carbon source is one or more of coconut shell, peanut, peanut meal, soybean, and soybean meal.

[0022] Preferably, the precursor of the active component is a soluble salt containing one or more of Fe, Co, Ni, and Cu, and is preferably one or more of cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt acetate, nickel chloride, nickel sulfate, nickel nitrate, nickel acetate, ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, copper chloride, copper sulfate, copper nitrate, copper acetate, and their hydrates.

[0023] Preferably, the pore-forming agent is one or more of potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium nitrate, potassium sulfate, magnesium chloride, magnesium nitrate, magnesium sulfate, calcium chloride, calcium nitrate, and their hydrates.

[0024] Preferably, the method further includes: homogenizing the mixture of biomass carbon source, precursor of active component and pore-forming agent, or homogenizing biomass carbon source and then mixing it with precursor of active component and pore-forming agent.

[0025] Preferably, the homogenization process is carried out by colloid milling or wet ball milling.

[0026] Preferably, the homogenization treatment results in a particle size Dv(90)≤500μm of the slurry, and more preferably Dv(90)≤200μm.

[0027] Preferably, the carbonization conditions include: calcining at a constant temperature of 600-1200℃ for 0.5-10 hours under an inert atmosphere; preferably, calcining at a constant temperature of 700-1000℃ for 1-5 hours.

[0028] Preferably, the acid washing results in a total K, Mg and / or Ca content in the obtained catalyst of ≤5 wt.%, more preferably ≤1 wt.%.

[0029] The third aspect of the present invention provides the application of the carbon-based catalyst of the present invention described above, or the carbon-based catalyst obtained by the preparation method of the carbon-based catalyst of the present invention described above, in the selective hydrogenation of aromatic nitro compounds, preferably in the selective hydrogenation of haloaromatic nitro compounds.

[0030] A fourth aspect of the present invention provides a method for selective hydrogenation of an aromatic nitro compound, the method comprising: reacting the aromatic nitro compound with hydrogen gas in the presence of a catalyst; wherein the catalyst is the carbon-based catalyst of the present invention described above, or a carbon-based catalyst obtained by the preparation method of the carbon-based catalyst of the present invention described above.

[0031] Preferably, the aromatic nitro compound is a halogenated aromatic nitro compound; more preferably, it is one or more of halogenated nitrobenzene, halogenated dinitrobenzene, and halogenated nitrotoluene; more preferably, it is one or more of p-chloronitrobenzene, o-chloronitrobenzene, m-chloronitrobenzene, 2,4-dichloronitrobenzene, 2,6-dinitrochlorobenzene, 1-chloro-2,4-dinitrobenzene, p-fluoronitrobenzene, o-fluoronitrobenzene, m-fluoronitrobenzene, 2,4-difluoronitrobenzene, 2,6-dinitrofluorobenzene, 1-fluoro-2,4-dinitrobenzene, p-bromonitrobenzene, o-bromonitrobenzene, m-bromonitrobenzene, 2,4-dibromonitrobenzene, 1-bromo-2,4-dinitrobenzene, p-iodonitrobenzene, o-iodonitrobenzene, m-iodonitrobenzene, and 1-iodo-2,4-dinitrobenzene.

[0032] Preferably, the conditions for selective hydrogenation include a temperature of 70-200°C and a pressure of 0.5-5 MPa; more preferably, a temperature of 80-150°C and a pressure of 0.7-3 MPa.

[0033] Through the above technical solution, the present invention has the following beneficial effects:

[0034] 1. This invention uses inexpensive renewable biomass raw materials as carbon sources and inexpensive transition metal compounds as precursors. The raw materials for the catalyst are inexpensive and readily available. The catalyst preparation method is simple, has a short process, low energy consumption, and low overall production cost.

[0035] 2. Compared with conventional activated carbon supported catalysts, this invention fully mixes the inexpensive transition metal precursor with a biomass carbon source containing P and S and then carbonizes them together. It also takes advantage of the high dispersion of P and S sites in the biomass carbon source, which is conducive to the contact and coordination of metal atoms with P and S on the activated carbon support, thereby innovatively forming highly dispersed catalyst active centers.

[0036] 3. The catalyst prepared by this invention uses an acid washing process after carbonization, which can effectively remove pore-forming agents and excess metal particles, expose more active sites, and the catalyst has a high specific surface area, rich pore structure, high pore volume, and high activity and selectivity. Attached Figure Description

[0037] Figure 1 The conversion and selectivity results of 10 cycles of performance testing of the catalyst in Example 1 for the selective hydrogenation of p-chloronitrobenzene to p-chloroaniline are shown.

[0038] Figure 2 The conversion and selectivity results of 10 cycles of performance testing of the catalyst in Example 2 for the selective hydrogenation of p-chloronitrobenzene to p-chloroaniline are shown. Detailed Implementation

[0039] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0040] The first aspect of the present invention provides a carbon-based catalyst, the carbon-based catalyst comprising an activated carbon support and an active component supported on the activated carbon support;

[0041] The activated carbon support is an activated carbon support containing S and P; the active component contains one or more of Fe, Co, Ni and Cu.

[0042] In the carbon-based catalyst, the content of the active component is 0.05-5 wt.%, the content of S is 0.005-1 wt.%, and the content of P is 0.01-3 wt.%, relative to the total weight of the carbon-based catalyst.

[0043] According to the present invention, preferably, the catalyst has a specific surface area of ​​200-1000 m². 2 / g, preferably 300-800m 2 / g.

[0044] According to the present invention, preferably, the catalyst has a pore volume of 0.2-1.0 cm³. 3 / g, preferably 0.3-0.8cm 3 / g.

[0045] According to the present invention, preferably, the active component contains Co and / or Ni, and particularly preferably contains Co.

[0046] According to the present invention, the content of the active component relative to the total weight of the carbon-based catalyst is 0.05-5 wt.%, preferably 0.1-3 wt.%, more preferably 0.5-2 wt.%, and even more preferably 0.8-1.5 wt.%. The content of the active component can be, for example, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 4 wt.%, 4.5 wt.%, or 5 wt.%.

[0047] According to the present invention, preferably, the S content in the carbon-based catalyst is 0.01-0.8 wt.%, more preferably 0.03-0.5 wt.%, and the P content is 0.03-2 wt.%, more preferably 0.1-1 wt.%.

[0048] The sulfur (S) content in a carbon-based catalyst can be 0.01 wt.%, 0.02 wt.%, 0.03 wt.%, 0.04 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, or 0.8 wt.%, etc. The phosphorus (P) content in a carbon-based catalyst can be 0.03 wt.%, 0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, 1.5 wt.%, or 2 wt.%, etc.

[0049] According to the present invention, preferably, the carbon-based catalyst is composed of an activated carbon support and an active component supported on the activated carbon support.

[0050] As the activated carbon carrier containing S and P in this invention, the activated carbon carrier prepared by carbonization of carbon sources containing S and P can be used, or the activated carbon carrier modified with S and P can be used.

[0051] From the perspective of obtaining a carbon-based catalyst with superior performance in catalyzing the hydrogenation of aromatic nitro compounds, preferably, the carbon-based catalyst is obtained by carbonizing a mixture of a biomass carbon source, a precursor of the active component, and a pore-forming agent. The biomass carbon source can be, for example, one or more of the following: fruit kernels, coconut shells, durian shells, bamboo, peanuts, peanut meal, soybeans, soybean meal, rice straw, rice husks, rice bran, cassava stalks, and mushroom residue, preferably one or more of the following: coconut shells, peanuts, peanut meal, soybeans, and soybean meal. Specifically, peanut meal and soybean meal refer to the residue obtained after pressing peanuts and soybeans, respectively, and can be defatted peanut meal and defatted soybean meal.

[0052] By using the above-mentioned biomass carbon source, the activated carbon support containing S and P required by this invention can be obtained. Using the above preparation method, the conversion rate and selectivity of catalytic hydrogenation of aromatic nitro compounds can be further improved.

[0053] As a precursor to the active component, any active component of the carbon-based catalyst of the present invention can be obtained, without particular limitation; for example, it can be a soluble salt containing one or more of Fe, Co, Ni, and Cu, preferably one or more of cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt acetate, nickel chloride, nickel sulfate, nickel nitrate, nickel acetate, ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, copper chloride, copper sulfate, copper nitrate, copper acetate and their hydrates.

[0054] As a pore-forming agent, it can be one or more of potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium nitrate, potassium sulfate, magnesium chloride, magnesium nitrate, magnesium sulfate, calcium chloride, calcium nitrate, and their hydrates. By using a pore-forming agent, the specific surface area and pore volume of the catalyst can be further increased, thereby improving the conversion rate and selectivity of the catalytic hydrogenation of aromatic nitro compounds.

[0055] To further improve the performance of carbon-based catalysts, it is preferable that the particle size Dv(90) of the mixture of biomass carbon source, active component precursor, and pore-forming agent is ≤500 μm, and more preferably Dv(90) ≤200 μm. By preparing carbon-based catalysts using a mixture with the above particle size, the conversion and selectivity of catalytic hydrogenation of aromatic nitro compounds can be further improved.

[0056] The second aspect of the present invention provides a method for preparing a carbon-based catalyst, the method comprising: mixing a biomass carbon source, a precursor of an active component and a pore-forming agent in the presence of water, and then sequentially performing drying, carbonization treatment and acid washing.

[0057] The biomass carbon source is one or more of the following: fruit kernels, coconut shells, durian shells, bamboo, peanuts, peanut meal, soybeans, soybean meal, rice straw, rice husks, rice bran, cassava stalks, and mushroom residue.

[0058] The precursor of the active component contains one or more of Fe, Co, Ni, and Cu.

[0059] The method for preparing the carbon-based catalyst of the second aspect of the present invention can be used to prepare the carbon-based catalyst of the first aspect.

[0060] The biomass carbon source used to form the activated carbon carrier can be one or more of the following: fruit kernels, coconut shells, durian shells, bamboo, peanuts, peanut meal, soybeans, soybean meal, rice straw, rice husks, rice bran, cassava stalks, and mushroom residue. Preferably, it can be one or more of coconut shells, peanuts, peanut meal, soybeans, and soybean meal. These biomass carbon sources are readily available and inexpensive, which can significantly reduce the cost of carbon-based catalysts while ensuring their conversion rate and selectivity.

[0061] As a precursor to the active component, any precursor that yields the active component of the carbon-based catalyst of this invention is acceptable, without particular limitation. For example, it can be a soluble salt containing one or more of Fe, Co, Ni, and Cu, preferably one or more of cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt acetate, nickel chloride, nickel sulfate, nickel nitrate, nickel acetate, ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, copper chloride, copper sulfate, copper nitrate, copper acetate, and their hydrates. Among these, soluble salts containing Co and / or Ni are preferred.

[0062] As a pore-forming agent, it can be one or more of potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium nitrate, potassium sulfate, magnesium chloride, magnesium nitrate, magnesium sulfate, calcium chloride, calcium nitrate, and their hydrates. By using a pore-forming agent, the specific surface area of ​​the catalyst can be further increased, thereby improving the conversion rate and selectivity of the catalytic hydrogenation of aromatic nitro compounds.

[0063] According to the present invention, the mass ratio of biomass carbon source, active component precursor, and pore-forming agent can be 1:(0.005-1):(0.1-50), preferably 1:(0.01-0.5):(0.5-20), and more preferably 1:(0.01-0.5):(2-10). Preferably, by adjusting the mass ratio of biomass carbon source, active component precursor, and pore-forming agent, and combining it with an acid washing step, the content of active component in the obtained carbon-based catalyst is 0.05-5 wt.%, preferably 0.1-3 wt.%. Furthermore, the content of activated carbon support can be 95-99.95 wt.%, preferably 97-99.9 wt.%.

[0064] To further improve the performance of carbon-based catalysts, it is preferable to control the particle size of the mixture of biomass carbon source, active component precursor, and pore-forming agent, for example, to make the particle size Dv(90) ≤ 500 μm, preferably Dv(90) ≤ 200 μm. By preparing carbon-based catalysts using a mixture with the above particle size, the conversion and selectivity of catalytic hydrogenation of aromatic nitro compounds can be further improved.

[0065] Specifically, the particle size Dv(90) of the mixture can be controlled by homogenization as follows: homogenizing the mixture of biomass carbon source, active component precursor, and pore-forming agent, or homogenizing the biomass carbon source before mixing it with the active component precursor and pore-forming agent. Preferably, the homogenization process results in a particle size Dv(90) ≤ 500 μm, more preferably Dv(90) ≤ 200 μm. The homogenization process can be performed using a colloid mill or wet ball milling.

[0066] According to the present invention, the mixture of the above-mentioned biomass carbon source, the precursor of the active component, and the pore-forming agent is dried and then subjected to carbonization treatment. The drying conditions can be those commonly used for drying carbonaceous materials, for example: a temperature of 80-250°C, preferably 100-200°C, and a time of 5-48 h, preferably 10-24 h. In preparing the powdered carbon-based catalyst, the dried material can be ground into powder before carbonization.

[0067] According to the present invention, the carbonization conditions may include: calcining at a constant temperature of 600-1200°C for 0.5-10 hours under an inert atmosphere; preferably, calcining at a constant temperature of 700-1000°C for 1-5 hours. The inert atmosphere may be a nitrogen atmosphere or an inert gas atmosphere (e.g., an argon atmosphere). The carbonization heating rate may be 1-20°C / min, preferably 3-10°C / min. Specific calcination temperatures may be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, or 1200°C, etc.

[0068] According to the present invention, acid washing results in a total content of K, Mg and / or Ca in the obtained catalyst of ≤5 wt.%, preferably ≤1 wt.%, more preferably ≤0.5 wt.%. In the present invention, the total content of K, Mg and / or Ca refers to the total content of the three elements in the presence of K, Mg and Ca, or the content of one or two of K, Mg and Ca in the presence of K, Mg and Ca, or the total content of the two.

[0069] Acid washing is used to remove the pore-forming agent, and after washing with water and drying, the carbon-based catalyst of the present invention can be obtained. Acid washing can be carried out, for example, with 0.1-2 mol / L hydrochloric acid, nitric acid, etc.

[0070] In this invention, depending on the desired morphology of the catalyst, the material mixture can be appropriately shaped or treated with binders before carbonization to obtain a catalyst of the desired size and particle size.

[0071] (i) In the case of preparing the molding catalyst, the preferred biomass carbon source is one or more of the following: fruit kernels, coconut shells, durian shells, bamboo, rice bran, rice straw, rice husks, cassava stalks, and mushroom residue. Furthermore, it is preferable to mix a binder into the mixture of the biomass carbon source, the precursor of the active component, and the pore-forming agent to assist in molding; suitable binders include silica sol and alumina sol. If necessary, a pH adjuster such as nitric acid can also be mixed into the above mixture. By adjusting the pH value of the overall material using a pH adjuster, the material is placed under acidic conditions, under which silica sol and alumina sol can exert their maximum binding effect. In addition, acid can dissolve some components in the biomass; for example, acid can cause hydrolysis of cellulose, promoting the homogenization of the biomass raw material.

[0072] (ii) In the case of preparing powders or small particles, the preferred biomass carbon source is one or more of peanuts and peanut meal.

[0073] The third aspect of the present invention provides the application of the above-described carbon-based catalyst, or the carbon-based catalyst obtained by the above preparation method, in the selective hydrogenation of aromatic nitro compounds, preferably in the selective hydrogenation of haloaromatic nitro compounds.

[0074] A fourth aspect of the present invention provides a method for selective hydrogenation of an aromatic nitro compound, the method comprising: reacting the aromatic nitro compound with hydrogen gas in the presence of a catalyst; wherein the catalyst is the carbon-based catalyst described above, or a carbon-based catalyst obtained by the method for preparing the carbon-based catalyst described above.

[0075] In this invention, there is no particular limitation on the aromatic nitro compound, but it is preferably a haloaromatic nitro compound, such as halonitrobenzene, halodinitrobenzene, halonitrotoluene, etc.

[0076] Specifically, the haloaryl nitro compound can be one or more of the following: p-chloronitrobenzene, o-chloronitrobenzene, m-chloronitrobenzene, 2,4-dichloronitrobenzene, 2,6-dinitrochlorobenzene, 1-chloro-2,4-dinitrobenzene, p-fluoronitrobenzene, o-fluoronitrobenzene, m-fluoronitrobenzene, 2,4-difluoronitrobenzene, 2,6-dinitrofluorobenzene, 1-fluoro-2,4-dinitrobenzene, p-bromonitrobenzene, o-bromonitrobenzene, m-bromonitrobenzene, 2,4-dibromonitrobenzene, 1-bromo-2,4-dinitrobenzene, p-iodonitrobenzene, o-iodonitrobenzene, m-iodonitrobenzene, and 1-iodo-2,4-dinitrobenzene. Preferably, it is p-chloronitrobenzene, o-chloronitrobenzene, m-chloronitrobenzene, 2,4-dichloronitrobenzene, or 2,6-dinitrochlorobenzene.

[0077] Conditions for selective hydrogenation may include, for example, a temperature of 70-200°C and a pressure of 0.5-5 MPa; preferably, a temperature of 80-150°C and a pressure of 0.7-3 MPa.

[0078] The present invention will be described in detail below through examples. In the following examples, the specific surface area was determined using a nitrogen physical adsorption-desorption method.

[0079] In the following examples, the particle size Dv(90) value refers to the particle size corresponding to the cumulative particle size distribution of the sample reaching 90%, which is determined by laser particle size analysis (Malvin laser particle size analyzer Mastersizer 3000).

[0080] In the following examples, the Co, Ni, and P contents were measured by inductively coupled plasma atomic emission spectrometry (USA, PE Avio 200), and the S content was measured by an organic elemental analyzer (Germany, Elemantar: Vario EL cube).

[0081] Example 1

[0082] Take 10g of dried bamboo and crush it into powder to obtain bamboo powder. Take 1g of Co(NO3)2·6H2O and completely dissolve it in 300ml of deionized water. Add the bamboo powder to the Co(NO3)2 aqueous solution and stir until a uniform slurry is formed. Then add 60g of Mg(NO3)2·6H2O to the slurry and stir evenly. Ball mill the above slurry to control the Dv(90) of the slurry to 50μm. Dry the ball-milled slurry and then grind it into powder.

[0083] The powder was placed in a tube furnace and heated to 800℃ at a rate of 5℃ / min under nitrogen purging, and calcined at this temperature for 3 hours. Afterwards, the calcined material was cooled to room temperature under nitrogen purging, and the carbonized material was removed. The material was then acid-washed with 1L of 1mol / L hydrochloric acid solution at a constant temperature of 95℃, followed by filtration and washing with deionized water. Finally, the filtered material was dried in an 80℃ drying oven for 10 hours to obtain the final catalyst sample. During the acid washing step, the Mg content in the sample was controlled to be ≤0.5wt.%.

[0084] The elemental composition of the catalyst was analyzed, revealing a Co content of 1.01 wt.%, a S content of 0.03 wt.%, and a P content of 0.11 wt.%. N₂ adsorption characterization of the catalyst showed a specific surface area of ​​624 m². 2 / g.

[0085] Example 2

[0086] In Example 1, the dried bamboo was replaced with dried soybean meal as the raw material, while the rest of the preparation process remained the same. The final catalyst contained 0.87 wt.% Co, 0.21 wt.% S, and 0.84 wt.% P, with a specific surface area of ​​633 m². 2 / g.

[0087] Example 3

[0088] In Example 1, the dried bamboo was replaced with dried soybeans as the raw material, while the rest of the preparation process remained the same. The final catalyst contained 0.95% Co, 0.17 wt.% S, and 0.53 wt.% P, with a specific surface area of ​​651 m². 2 / g.

[0089] Example 4

[0090] The pore-forming agent in Example 2 was replaced with KOH, and the K content in the sample was controlled to be ≤0.5 wt.% during the acid washing step, while the rest of the preparation process remained the same. The final catalyst contained 0.83 wt.% Co, 0.20 wt.% S, and 0.85 wt.% P, with a specific surface area of ​​976 m². 2 / g.

[0091] Example 5

[0092] In Example 1, the dried bamboo was replaced with dried coconut shells as the raw material, while the rest of the preparation process remained the same. The final catalyst contained 1.12 wt.% Co, 0.11 wt.% S, and 0.21 wt.% P, with a specific surface area of ​​683 m². 2 / g.

[0093] Example 6

[0094] In Example 2, Co(NO3)2·6H2O was replaced with NiCl2·6H2O, while the rest of the preparation process remained the same. The final catalyst contained 1.51 wt.% Ni, 0.19 wt.% S, and 0.83 wt.% P, with a specific surface area of ​​609 m². 2 / g.

[0095] Example 7

[0096] In Example 1, the amount of Mg(NO3)2·6H2O was changed from 60g to 10g, while the rest of the preparation process remained unchanged. The final catalyst contained 0.79 wt.% Co, 0.04 wt.% S, and 0.12 wt.% P, with a specific surface area of ​​267 m². 2 / g.

[0097] Example 8

[0098] In the ball milling process of Example 1, the Dv(90) of the slurry was controlled to be 200 μm, while the rest of the preparation process remained unchanged. The final catalyst contained 0.93 wt.% Co, 0.03 wt.% S, and 0.12 wt.% P, with a specific surface area of ​​573 m². 2 / g.

[0099] Example 9

[0100] In the ball milling process of Example 1, the Dv(90) of the slurry was controlled to be 100 μm, while the rest of the preparation process remained unchanged. The final catalyst contained 0.86 wt.% Co, 0.03 wt.% S, and 0.12 wt.% P, with a specific surface area of ​​595 m². 2 / g.

[0101] Example 10

[0102] The carbonization isothermal calcination temperature in Example 1 was changed from 800℃ to 750℃, while the rest of the preparation process remained unchanged. The final catalyst contained 0.93 wt.% Co, 0.04 wt.% S, and 0.13 wt.% P, with a specific surface area of ​​710 m². 2 / g.

[0103] Example 11

[0104] The carbonization isothermal calcination temperature in Example 1 was changed from 800℃ to 850℃, while the rest of the preparation process remained unchanged. The final catalyst contained 0.96 wt.% Co, 0.02 wt.% S, and 0.12 wt.% P, with a specific surface area of ​​601 m². 2 / g.

[0105] Example 12

[0106] The carbonization isothermal calcination temperature in Example 1 was changed from 800℃ to 1000℃, while the rest of the preparation process remained unchanged. The final catalyst contained 0.97 wt.% Co, 0.01 wt.% S, and 0.1 wt.% P, with a specific surface area of ​​489 m². 2 / g.

[0107] Test Example 1: The catalyst prepared in Example 1 was used to catalyze the hydrogenation of p-chloronitrobenzene to p-chloroaniline.

[0108] 500 mg of p-chloronitrobenzene, 100 mg of the catalyst from Example 1, 50 mL of ethanol, and 50 mL of water were added to a 200 mL stainless steel autoclave. The autoclave was first purged with nitrogen three times, then purged with hydrogen three times, and finally purged with hydrogen to 1 MPa and sealed. The autoclave was heated to 100°C, and the reaction mixture was magnetically stirred. After reacting for 3 hours, the autoclave was cooled. The catalyst was separated from the reaction mixture by centrifugation, and the reaction mixture was analyzed by liquid chromatography. The catalyst obtained by centrifugation was then subjected to another round of catalytic performance testing, for a total of 10 cycles. The p-chloronitrobenzene conversion and p-chloroaniline selectivity after 10 cycles are shown in the figure below. Figure 1 As shown.

[0109] from Figure 1 It can be seen that the conversion rate of chloronitrobenzene in the first experiment was 99.9%, and the selectivity for chloroaniline was 99.9%. After 10 cycles of experiments, the conversion rate of chloronitrobenzene remained above 99%, and the selectivity for chloroaniline remained above 99%, indicating that the catalyst exhibited good catalytic activity, selectivity, and stability.

[0110] Test Example 2: The catalyst prepared in Example 2 was used to catalyze the hydrogenation of p-chloronitrobenzene to p-chloroaniline.

[0111] The catalyst prepared in Example 2 was used to catalyze the hydrogenation of p-chloronitrobenzene to p-chloroaniline. The experimental procedure and conditions were consistent with those in Test Example 1, and the performance test was conducted for a total of 10 cycles. The p-chloronitrobenzene conversion and p-chloroaniline selectivity after 10 cycles are as follows: Figure 2 As shown.

[0112] from Figure 2It can be seen that the conversion rate of chloronitrobenzene in the first experiment was 99.9%, and the selectivity for chloroaniline was 99.9%. After 10 cycles of experiments, the conversion rate of chloronitrobenzene remained above 99%, and the selectivity for chloroaniline remained above 99%, indicating that the catalyst exhibited good catalytic activity, selectivity, and stability.

[0113] Test Example 3-20

[0114] In Test Examples 3-20, the catalysts prepared in Examples 1-12 were used to catalyze the hydrogenation reaction of various haloaromatic nitro compounds to prepare the corresponding haloaromatic amines. The types of reactants used in each test example are listed in Table 1. The experimental procedures and conditions were consistent with those in Test Example 1. The conversion rates of the reactants and the selectivity of the corresponding haloaromatic amines in the first test are listed in Table 1.

[0115] Table 1. Conversion and selectivity of halogenated aromatic amines catalyzed by different catalysts

[0116]

[0117] The results in Table 1 show that by setting the Co content to 0.8-1.5 wt.%, the S content to 0.03-0.5 wt.%, and the P content to 0.1-1 wt.%, the conversion rate and selectivity of the halogenated aromatic hydrocarbons of the catalyst can be improved.

[0118] The comparison between Test Example 1 and Test Example 6 shows that the catalyst containing Co has higher conversion rate and selectivity than the catalyst containing Ni.

[0119] A comparison between Test Example 1 and Test Example 7 shows that by making the mass ratio of biomass carbon source to pore-forming agent 1:2-10, the conversion rate and selectivity of the catalyst can be further improved.

[0120] A comparison of Test Example 1 with Test Examples 8-9 shows that by making the Dv(90) of the slurry less than 100 μm, preferably less than 50 μm, the conversion rate and selectivity of the catalyst can be further improved.

[0121] A comparison of Test Example 1 with Test Examples 10-12 shows that by setting the carbonization isothermal calcination temperature to 750-850℃, the conversion rate and selectivity of the catalyst can be further improved.

[0122] Comparative Example 1

[0123] A 1 wt.% Co / C catalyst was prepared by impregnation and used in the hydrogenation of p-chloronitrobenzene to aniline. The carbon support used had a specific surface area of ​​800 m². 2 / g of commercial activated carbon (Tianjin Guangfu Technology Development Co., Ltd., activated carbon (powder), analytical grade). The activated carbon powder was first dried at 120℃ for 12h. 10g of the dried activated carbon powder and 0.41g of cobalt chloride hexahydrate were weighed, and the cobalt chloride hexahydrate solution was prepared and impregnated onto the activated carbon support. After drying and calcination at 800℃ under an inert atmosphere for 2h, a 1wt.% Co / C catalyst was obtained after cooling.

[0124] The method of Test Example 1 was used to hydrogenate chloronitrobenzene, and the conversion rate of p-chloronitrobenzene was detected to be 35.3%, and the selectivity of p-chloroaniline was 83.4%.

[0125] Comparative Example 2

[0126] The dried bamboo in Example 1 was replaced with bovine serum albumin (BSA), while the rest of the preparation process remained unchanged. The final catalyst contained 1.23 wt.% Co, 0.31 wt.% S, and less than 0.002 wt.% P, with a specific surface area of ​​657 m². 2 / g.

[0127] The method of Test Example 1 was used to hydrogenate chloronitrobenzene, and the conversion rate of p-chloronitrobenzene was detected to be 87.9%, and the selectivity of p-chloroaniline was 93.1%.

[0128] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. The application of a carbon-based catalyst in the selective hydrogenation of aromatic nitro compounds to prepare haloaromatic amines, wherein, The aromatic nitro compound is a haloaromatic nitro compound. The carbon-based catalyst includes an activated carbon support and an active component supported on the activated carbon support; The activated carbon carrier is an activated carbon carrier containing S and P; The active component is Co and / or Ni; In the carbon-based catalyst, the content of the active component is 0.8-1.5 wt.%, the content of S is 0.03-0.5 wt.%, and the content of P is 0.1-1 wt.%, relative to the total weight of the carbon-based catalyst.

2. The application according to claim 1, wherein, The carbon-based catalyst is obtained by carbonizing a mixture of biomass carbon source, precursor of active component, and pore-forming agent. The biomass carbon source is one or more of coconut shell, peanut, peanut meal, soybean, and soybean meal; The particle size of the mixture, Dv(90), is ≤50μm.

3. A method for selectively hydrogenating aromatic nitro compounds to prepare haloaromatic amines, characterized in that, The method includes: reacting an aromatic nitro compound with hydrogen gas in the presence of a carbon-based catalyst; The aromatic nitro compound is a haloaromatic nitro compound. The carbon-based catalyst includes an activated carbon support and an active component supported on the activated carbon support; The activated carbon carrier is an activated carbon carrier containing S and P; The active component is Co and / or Ni; In the carbon-based catalyst, the content of the active component is 0.8-1.5 wt.%, the content of S is 0.03-0.5 wt.%, and the content of P is 0.1-1 wt.%, relative to the total weight of the carbon-based catalyst.

4. The method according to claim 3, wherein, The carbon-based catalyst is obtained by carbonizing a mixture of biomass carbon source, precursor of active component, and pore-forming agent. The biomass carbon source is one or more of coconut shell, peanut, peanut meal, soybean, and soybean meal; The particle size of the mixture, Dv(90), is ≤50μm.

5. The method according to claim 3, wherein, The aromatic nitro compound is one or more of halonitrobenzene, halodinitrobenzene, and halonitrotoluene.

6. The method according to claim 3, wherein, The aromatic nitro compound is one or more of the following: p-chloronitrobenzene, o-chloronitrobenzene, m-chloronitrobenzene, 2,4-dichloronitrobenzene, 2,6-dinitrochlorobenzene, 1-chloro-2,4-dinitrobenzene, p-fluoronitrobenzene, o-fluoronitrobenzene, m-fluoronitrobenzene, 2,4-difluoronitrobenzene, 2,6-dinitrofluorobenzene, 1-fluoro-2,4-dinitrobenzene, p-bromonitrobenzene, o-bromonitrobenzene, m-bromonitrobenzene, 2,4-dibromonitrobenzene, 1-bromo-2,4-dinitrobenzene, p-iodonitrobenzene, o-iodonitrobenzene, m-iodonitrobenzene, and 1-iodo-2,4-dinitrobenzene.

7. The method according to claim 3, wherein, The conditions for selective hydrogenation include a temperature of 70-200℃ and a pressure of 0.5-5MPa.

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