Shaped catalysts and methods for their preparation, catalytic hydrogenation of chloroaromatic nitro compounds

Abstract

This invention relates to the field of catalyst technology, and discloses a shaped catalyst and its preparation method, as well as a method for the catalytic hydrogenation of chloroaromatic nitro compounds. The preparation method includes: mixing a catalyst matrix, coal tar, and a first solvent, followed by shaping and calcination; the calcination temperature is not higher than 500°C; wherein the catalyst matrix comprises transition metal particles and a graphitized carbon layer shell coating the surface of the transition metal particles. The shaped carbon-coated metal catalyst prepared by this method can achieve a maximum conversion rate of 100% for chloroaromatic nitro compounds.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a shaped catalyst and its preparation method, and a catalytic hydrogenation method for chlorinated aromatic nitro compounds. Background Technology

[0002] In recent years, a class of core-shell carbon-coated metal nanocomposites, with a single-layer to multi-layer graphene-like outer shell and a metal nanoparticle core, have attracted widespread attention. Carbon-coated metal nanocomposites are a class of composite materials with metal (or oxide, carbide, phosphide, nitride, sulfide, etc.) nanoparticles as the core and carbon materials (graphene-like, carbon nanotubes, amorphous carbon, etc.) as the outer shell.

[0003] Carbon-coated metal composites can serve as intrinsically safe catalysts for the selective hydrogenation of chloroaromatic nitro compounds. For example, Tang et al. (RSC Advances, 2017, 7(3): 1531-1539.) prepared a carbon-coated nickel catalyst using metal-organic frameworks (MOFs) as precursors and applied it to the selective hydrogenation of chloronitrobenzenes. When the conversion of p-nitrochlorobenzene was >99.9%, the selectivity of the target product to chloroaniline was 94.3%. Pan et al. (Molecular Catalysis, 2020, 485: 110838.) also prepared a nitrogen-doped carbon-coated nickel catalyst using MOFs as precursors. When the conversion of p-nitrochlorobenzene was 94.0%, the selectivity of the target product to chloroaniline was 92.1%.

[0004] It can be seen that while existing carbon-coated metal composite materials can achieve high conversion rates when applied to chlorinated aromatic nitro compounds, the selectivity of the target product is low. Furthermore, existing methods for preparing carbon-coated metal composite materials suffer from drawbacks such as cumbersome steps, the need for large amounts of organic solvents, the high cost of some ligands, and the lack of effective molding methods, hindering large-scale application. Therefore, achieving a green, simple, and low-cost method for preparing and molding carbon-coated metal composite materials is a significant challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low mechanical strength and poor selectivity of carbon-coated metal composite materials in the prior art when applied to chlorinated aromatic nitro compounds. This invention provides a molded catalyst and its preparation method, as well as a catalytic hydrogenation method for chlorinated aromatic nitro compounds. The molded catalyst prepared by this method has high side-pressure crushing strength and good catalytic hydrogenation performance with high selectivity for the target product.

[0006] To achieve the above objectives, the present invention provides a method for preparing a shaped catalyst, the method comprising: mixing a catalyst matrix, coal tar and a first solvent, and then performing shaping and calcination; wherein the calcination temperature is not higher than 500°C;

[0007] The catalyst matrix comprises transition metal particles and a graphitized carbon layer shell covering the surface of the transition metal particles.

[0008] Preferably, the mass ratio of coal tar to catalyst matrix is ​​(0.1-0.5):1, more preferably (0.3-0.5):1.

[0009] A second aspect of the present invention provides a molding catalyst prepared by the above-described preparation method.

[0010] Preferably, the pore volume of the molded catalyst is 0.05-0.15 cm³. 3 / g.

[0011] Preferably, the specific surface area of ​​the shaped catalyst is 15-40 m². 2 / g.

[0012] Preferably, the side crushing strength of the shaped catalyst is 60-120 N / cm.

[0013] A third aspect of the present invention provides a method for the catalytic hydrogenation of a chlorinated aromatic nitro compound, the method comprising: contacting the chlorinated aromatic nitro compound with a catalyst under hydrogenation reaction conditions;

[0014] The catalyst is the molding catalyst described in the second aspect.

[0015] The method for preparing a molded catalyst provided by this invention involves mixing and molding a carbon-coated metal catalyst matrix with coal tar, followed by calcination. The calcination temperature is no higher than 500℃, significantly lower than the conventional catalyst carbonization preparation temperature. Through the synergistic effect of coal tar and the catalyst matrix, the resulting molded catalyst exhibits high catalytic hydrogenation activity while maintaining high lateral crushing strength, meeting the needs of industrial applications. Under mild reaction conditions, the prepared carbon-coated metal catalyst can achieve 100% conversion of chlorinated aromatic nitro compounds with high selectivity for the target product. The preparation method provided by this invention uses coal tar as a raw material, mixing and molding it with a carbon-coated metal catalyst matrix. It is green, simple, and low-cost, making it suitable for large-scale industrial production. Attached Figure Description

[0016] Figure 1 The BET specific surface area curve of the shaped catalyst prepared in Example 1;

[0017] Figure 2 This is the combined pore volume and pore size distribution curve of the shaped catalyst prepared in Example 1;

[0018] Figure 3 This is the BET specific surface area curve of the shaped catalyst prepared in Example 4. Detailed Implementation

[0019] 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.

[0020] The first aspect of the present invention provides a method for preparing a shaped catalyst, the method comprising: mixing a catalyst matrix, coal tar and a first solvent, and then shaping and calcining the shaped catalyst;

[0021] The catalyst matrix comprises transition metal particles and a graphitized carbon layer shell covering the surface of the transition metal particles.

[0022] According to the present invention, the shaped catalyst prepared by the above preparation method has high catalytic hydrogenation activity under the synergistic effect of coal tar and catalyst matrix, and can also ensure that the prepared shaped catalyst has high lateral crushing strength, which can meet the needs of industrial applications.

[0023] Traditional molding methods that involve adding alumina binders may result in the catalyst matrix being completely encapsulated, making it difficult to exert catalytic activity in the catalytic hydrogenation reaction of chlorinated aromatic nitro compounds.

[0024] In this invention, "coal tar" has the conventional definition in the art, referring to a liquid product obtained during coal carbonization. This invention has a wide range of coal tar options; coal tar obtained from any coal carbonization process can be used, for example, any one of low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar. This invention does not particularly limit the source of the coal tar; it can be commercially available. The coal tar used in the examples was purchased from Thermo Fisher Scientific, brand number 42488-Q08F005.

[0025] According to some preferred embodiments of the present invention, the mass ratio of coal tar to catalyst matrix is ​​(0.1-0.5):1, for example, it can be a specific but not limiting mass ratio or any range between two such ratios, such as 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, etc. Preferably, the mass ratio of coal tar to catalyst matrix is ​​(0.3-0.5):1. Controlling the amount of coal tar within the above preferred range is beneficial for the obtained shaped catalyst to have suitable lateral crushing strength.

[0026] According to some preferred embodiments of the present invention, the mass ratio of the first solvent to the catalyst matrix is ​​(0.01-0.1):1, for example, it can be a specific but not limiting mass ratio or any range between two such ratios, such as 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, etc. Preferably, the mass ratio of the first solvent to the catalyst matrix is ​​(0.01-0.05):1.

[0027] Preferably, the first solvent is water.

[0028] The present invention does not impose any particular limitations on the mixing method and conditions of the catalyst matrix, coal tar and the first solvent, as long as the components can be mixed evenly. The mixing can be carried out by mechanical stirring, such as by using a kneading machine.

[0029] The present invention does not particularly limit the molding method, and any conventional method in the art can be used for molding, such as extrusion molding, ball rolling molding, sheet forming, etc. Those skilled in the art can choose according to actual application needs.

[0030] According to some preferred embodiments of the present invention, the molding method is extrusion molding. Molded catalysts prepared by extrusion molding are suitable for fixed-bed reactors and are beneficial for large-scale production.

[0031] According to the present invention, an optional drying step may be performed after the molding step. The present invention does not have any particular limitations on this step, and it can be carried out in a conventional manner and under conventional conditions.

[0032] In this invention, the calcination temperature is no higher than 500°C. This temperature is significantly lower than the preparation temperature of conventional catalyst carbonization. This invention utilizes mixed coal tar to heat-treat the carbon-coated metal catalyst at a relatively low temperature to form it; excessively high temperatures may lead to catalyst deactivation. Preferably, the calcination temperature is 200-500°C, more preferably 280-390°C, and the time is 0.5-5 hours, more preferably 1-3 hours. By adopting the above-mentioned preferred embodiments, it is possible to ensure that the prepared shaped catalyst has a suitable number and structure of pores, thereby possessing suitable catalytic activity, and also exhibiting high lateral crushing strength, which can meet the needs of industrial applications.

[0033] Preferably, the molding and calcination are carried out under a protective atmosphere, which may be provided by an inert gas that does not participate in the reaction, such as nitrogen and / or argon.

[0034] The present invention does not particularly limit the source of the catalyst matrix, and it can be prepared by any method known in the art. The transition metal in the catalyst matrix exists in elemental form.

[0035] According to some preferred embodiments of the present invention, the method for preparing the catalyst matrix includes:

[0036] (1) A homogeneous solution is obtained by mixing a transition metal source, a polycarboxylic acid, and a second solvent;

[0037] (2) Remove the second solvent from the homogeneous solution to obtain the precursor;

[0038] (3) The precursor is heat-treated in an inert atmosphere and / or a reducing atmosphere.

[0039] The present invention has a wide range of choices for the transition metal source, such as at least one of the hydroxides, oxides, carbonates and acetates of the transition metal.

[0040] The present invention allows for a wide range of selection for the transition metal. Preferably, the transition metal is selected from at least one of nickel, cobalt, and manganese; more preferably, the transition metal is nickel. Under these preferred conditions, it is advantageous to further improve the catalytic activity and selectivity of the prepared shaped catalyst.

[0041] According to the present invention, the polycarboxylic acid contains at least two carboxyl groups, and preferably, the polycarboxylic acid is selected from at least one of ethylenediaminetetraacetic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, 1,3-propanediaminetetraacetic acid, citric acid, maleic acid, trimesic acid, terephthalic acid and malic acid.

[0042] According to some preferred embodiments of the present invention, the molar ratio of the transition metal source (based on metal element) to the polycarboxylic acid (based on carboxyl group) is 1:(2-12), preferably 1:(4-9). Controlling the molar ratio of the transition metal source to the polycarboxylic acid within the above-mentioned preferred range is beneficial for forming a complete carbon-coated structure.

[0043] The present invention does not have any particular limitation on the method of forming the homogeneous solution in step (1). For example, it can be formed by heating, stirring, etc. The present invention also does not have any particular limitation on the specific conditions of heating or stirring, as long as the homogeneous solution can be formed.

[0044] The present invention does not particularly limit the type of the second solvent, as long as it can form a homogeneous solution. For example, the solvent can be water, ethanol, etc., preferably water. The amount of the second solvent is also not particularly limited, again as long as it can form a homogeneous solution. The solvent in the homogeneous solution can be removed by direct evaporation. The evaporation temperature and process can employ existing techniques known to those skilled in the art. For example, the solvent in the homogeneous solution can be removed by thorough drying in an oven.

[0045] According to some preferred embodiments of the present invention, the conditions for the heat treatment in step (3) include: a temperature of 280-600℃, preferably 450-600℃, a time of 60-180min, preferably 60-120min; and a heating rate of 0.2-10℃ / min, preferably 1-10℃ / min.

[0046] In some embodiments of the present invention, preferably, the inert atmosphere is provided by at least one of nitrogen, argon, neon, and helium, and more preferably by a nitrogen atmosphere and / or an argon atmosphere. The reducing atmosphere may be, for example, hydrogen.

[0047] According to a particularly preferred embodiment of the present invention, the method for preparing the molding catalyst includes:

[0048] (1) A homogeneous solution is obtained by mixing a transition metal source, a polycarboxylic acid, and a second solvent;

[0049] (2) Remove the second solvent from the homogeneous solution to obtain the precursor;

[0050] (3) The precursor is heat-treated in an inert atmosphere and / or a reducing atmosphere to obtain a catalyst matrix;

[0051] (4) The catalyst matrix, coal tar and water are mixed, and then shaped and calcined.

[0052] The molding and calcining temperature is 200-500℃, preferably 280-390℃, and the time is 0.5-5h, preferably 1-3h.

[0053] A second aspect of the present invention provides a molding catalyst prepared by the above-described preparation method.

[0054] Preferably, the pore volume of the molded catalyst is 0.05-0.15 cm³. 3 / g, preferably 0.05-0.15cm 3 / g.

[0055] Preferably, the specific surface area of ​​the shaped catalyst is 15-40 m². 2 / g, preferably 25-40m 2 / g.

[0056] Preferably, the side crushing strength of the shaped catalyst is 60-120 N / cm, and more preferably 70-120 N / cm.

[0057] In this invention, the pore volume and specific surface area of ​​the shaped catalyst are measured in accordance with GB / T19587-2004 "Determination of Specific Surface Area of ​​Solid Substances by Gas Adsorption BET Method".

[0058] The side crushing strength of the formed carbon-coated metal catalyst was measured using the ZQJ-Ⅱ intelligent particle strength tester produced by Dalian Intelligent Testing Machine Factory, in accordance with the industry standard HG / T2782-1996. The extruded catalyst strip was cut into 5mm strips, and 10 strips were randomly selected for measurement and the average value was calculated.

[0059] A third aspect of the present invention provides a catalytic hydrogenation method for a chlorinated aromatic nitro compound, the method comprising: contacting the chlorinated aromatic nitro compound with a catalyst under hydrogenation reaction conditions; wherein the catalyst is the molding catalyst described in the second aspect.

[0060] The present invention has a wide range of choices for the chlorinated aromatic nitro compounds, such as at least one of o-nitrochlorobenzene, m-nitrochlorobenzene, p-nitrochlorobenzene and dichloronitrobenzene.

[0061] According to some preferred embodiments of the present invention, the hydrogenation reaction conditions include: a reaction temperature of 40-200°C, preferably 60-120°C; a hydrogen pressure of 0.5-5 MPa, preferably 1-2 MPa; and a mass ratio of catalyst to chlorinated aromatic nitro compound of 1:(1-500), preferably 1:(10-500).

[0062] Preferably, the contact is carried out in the presence of a third solvent, which is preferably at least one selected from methanol, ethanol, water, isopropanol, and tetrahydrofuran. The present invention does not impose a particular limitation on the amount of the third solvent, and those skilled in the art can select it according to actual needs.

[0063] According to some preferred embodiments of the present invention, the third solvent comprises isopropanol and water, preferably, the volume ratio of isopropanol to water is (5-20):1.

[0064] The present invention will be described in detail below through embodiments.

[0065] The coal tar used in the following examples was purchased from Thermo Fisher Scientific, grade 42488-Q08F005.

[0066] In the following examples, the side-pressure crushing strength of the molded catalyst was tested using the ZQJ-Ⅱ intelligent particle strength testing machine manufactured by Dalian Intelligent Testing Machine Factory.

[0067] The BET specific surface area and pore volume of the molded catalyst were tested using a dual-station specific surface area and pore size analyzer.

[0068] Example 1

[0069] (1) Preparation of carbon-coated metal catalyst: Weigh 21.01g of citric acid monohydrate and 14.55g of basic nickel carbonate and add them to 150mL of deionized water. Stir at 100℃ to obtain a homogeneous solution and continue to heat to dry. Grind the solid to obtain the precursor.

[0070] (2) The precursor was placed in a ceramic boat, and then the ceramic boat was placed in the constant temperature zone of a tube furnace. Nitrogen gas was introduced at a flow rate of 100 mL / min, and the temperature was increased to 600 °C at a rate of 10 °C / min. After holding the temperature for 120 min, the heating was stopped, and the temperature was cooled to room temperature under a nitrogen atmosphere to obtain a carbon-coated metal catalyst.

[0071] (3) 10g of carbon-coated metal catalyst, 5g of coal tar, and 1mL of deionized water were mixed and kneaded to obtain an extruded strip. The obtained extruded strip was extruded into a cylindrical wet strip with a diameter of 1.2mm through a stainless steel cylindrical perforated plate in a twin-screw extruder. The wet strip was dried and then shaped into short strips.

[0072] (4) Take 1.5g of the obtained shaped short strip and place it in a ceramic boat. Then place the ceramic boat in the constant temperature zone of a tube furnace, introduce nitrogen gas at a flow rate of 100mL / min, and heat it to 300℃ at a rate of 10℃ / min. After holding the temperature for 120min, stop heating and cool it to room temperature under a nitrogen atmosphere to obtain the shaped carbon-coated metal catalyst A1.

[0073] The BET surface area diagram of the shaped catalyst A1 is shown below. Figure 1 As shown in the BET specific surface area diagram, the multi-point BET specific surface area of ​​the formed carbon-coated metal catalyst is 36.94 m². 2 / g.

[0074] Figure 2 The figure shows the combined pore volume and pore size distribution curve of the formed catalyst A1. It can be seen from the figure that the total pore volume of the formed carbon-coated metal catalyst is 0.113 cm³. 3 / g.

[0075] The compressive crushing strength of the shaped catalyst, as tested by an intelligent particle strength testing machine, was 80.2 N / cm.

[0076] Example 2

[0077] (1) Preparation of carbon-coated metal catalyst: Weigh 21.01g of citric acid monohydrate and 13g of basic nickel carbonate and add them to 150mL of deionized water. Stir at 100℃ to obtain a homogeneous solution and continue to heat to dry. Grind the solid to obtain the precursor.

[0078] (2) The precursor was placed in a ceramic boat, and then the ceramic boat was placed in the constant temperature zone of a tube furnace. Nitrogen gas was introduced at a flow rate of 100 mL / min, and the temperature was increased to 550 °C at a rate of 10 °C / min. After holding the temperature for 120 min, the heating was stopped, and the temperature was cooled to room temperature under a nitrogen atmosphere to obtain a carbon-coated metal catalyst.

[0079] (3) 10g of carbon-coated metal catalyst, 4g of coal tar, and 0.5mL of deionized water were mixed and kneaded to obtain an extruded strip. The obtained extruded strip was extruded into a cylindrical wet strip with a diameter of 1.2mm through a stainless steel cylindrical perforated plate in a twin-screw extruder. The wet strip was dried and then shaped into short strips.

[0080] (4) Take 1.5g of the obtained shaped short strip and place it in a ceramic boat. Then place the ceramic boat in the constant temperature zone of the tube furnace, introduce nitrogen gas at a flow rate of 100mL / min, and heat it to 300℃ at a rate of 10℃ / min. After holding the temperature for 120min, stop heating and cool it to room temperature under a nitrogen atmosphere to obtain the shaped carbon-coated metal catalyst A2.

[0081] The compressive crushing strength of the molded catalyst A2, as tested by an intelligent particle strength testing machine, was 68.7 N / cm.

[0082] Example 3

[0083] The method is the same as in Example 1, except that in step (3), the amount of coal tar used is 2.5g. The resulting shaped catalyst is designated as A3.

[0084] The BET specific surface area of ​​the molded catalyst A3 was determined to be 32.26 m² using a dual-station specific surface area and pore size analyzer. 2 / g, with a total adsorption pore volume of 0.106 cm³. 3 / g.

[0085] The compressive crushing strength of the shaped catalyst, tested using an intelligent particle strength testing machine, was 62.1 N / cm.

[0086] Example 4

[0087] The method is the same as in Example 1, except that in step (4), the calcination temperature is 400°C. The resulting shaped catalyst is denoted as A4.

[0088] The BET surface area diagram of the shaped catalyst A4 is shown below. Figure 3 As shown in the BET specific surface area diagram, the multi-point BET specific surface area of ​​the formed carbon-coated metal catalyst is 16.15 m². 2 / g.

[0089] The total adsorption pore volume of the molded catalyst A4, as determined by a dual-station surface area and pore size analyzer, is 0.054 cm³. 3 / g.

[0090] The compressive crushing strength of the shaped catalyst, tested using an intelligent particle strength testing machine, was 76.2 N / cm.

[0091] Example 5

[0092] The method is the same as in Example 1, except that in step (3), the amount of coal tar used is 10g. The resulting shaped catalyst is designated as A5.

[0093] The compressive crushing strength of the shaped catalyst, tested using an intelligent particle strength testing machine, was 30.5 N / cm.

[0094] Comparative Example 1

[0095] The method is the same as in Example 1, except that in step (4), the molding and calcination temperature is 600°C. The resulting molded catalyst is denoted as DA1.

[0096] The compressive crushing strength of the molded catalyst DA1, tested using an intelligent particle strength testing machine, was 74.5 N / cm.

[0097] Comparative Example 2

[0098] (1) Preparation of carbon-coated metal catalyst: Weigh 21.01g of citric acid monohydrate and 14.55g of basic nickel carbonate and add them to 150mL of deionized water. Stir at 100℃ to obtain a homogeneous solution and continue to heat to dry. Grind the solid to obtain the precursor.

[0099] (2) The precursor was placed in a ceramic boat, and then the ceramic boat was placed in the constant temperature zone of a tube furnace. Nitrogen gas was introduced at a flow rate of 100 mL / min, and the temperature was increased to 600 °C at a rate of 10 °C / min. After holding the temperature for 120 min, the heating was stopped, and the temperature was cooled to room temperature under a nitrogen atmosphere to obtain a carbon-coated metal catalyst.

[0100] (3) 10g of carbon-coated metal catalyst, 5g of pseudoboehmite powder, 1g of guar gum powder, and 10mL of deionized water were mixed and kneaded to obtain an extruded strip. The obtained extruded strip was extruded into a cylindrical wet strip with a diameter of 1.2mm through a stainless steel cylindrical perforated plate in a twin-screw extruder. The wet strip was dried and then shaped into short strips.

[0101] (4) Take 1.5g of the obtained shaped short strip and place it in a ceramic boat. Then place the ceramic boat in the constant temperature zone of the tube furnace, introduce nitrogen gas at a flow rate of 100mL / min, and heat it to 300℃ at a rate of 10℃ / min. After holding the temperature for 120min, stop heating and cool it to room temperature under a nitrogen atmosphere. The resulting shaped catalyst is denoted as DA2.

[0102] The compressive crushing strength of the shaped catalyst, tested using an intelligent particle strength testing machine, was 90.4 N / cm.

[0103] Application Example 1

[0104] 100 mg of shaped carbon-coated metal catalyst A1, 316 mg of p-nitrochlorobenzene, 27 mL of isopropanol, and 3 mL of water were added to a reactor. After purging the reactor three times with H2, the mixture was stirred and heated under low pressure to the predetermined reaction temperature of 80 °C. H2 was then introduced again to bring the pressure inside the reactor to 1 MPa. The reaction was continued for 90 minutes, after which heating was stopped, the reactor was cooled to room temperature, and the pressure was released. The product was then removed from the reactor and subjected to chromatographic analysis. The conversion rate of the reactants and the selectivity of the target product were calculated using the following formulas:

[0105] Conversion rate (%) = (mass of reactants already reacted / amount of reactants added) × 100%;

[0106] Selectivity (%) = Mass of target product / Mass of reaction product × 100%;

[0107] Analysis revealed that the conversion rate of p-nitrochlorobenzene was 100%, and the selectivity of p-chloroaniline was greater than 99%.

[0108] Application Example 2

[0109] 100 mg of shaped carbon-coated metal catalyst A2, 158 mg of p-nitrochlorobenzene, 27 mL of isopropanol, and 3 mL of water were added to a reaction vessel. After purging the reaction vessel with H2 three times, the vessel was stirred and heated under low pressure until the predetermined reaction temperature of 60 °C was reached. H2 was then introduced again to bring the pressure inside the reaction vessel to 1 MPa. The reaction was continued for 120 minutes, after which heating was stopped, the vessel was cooled to room temperature, the pressure was released, and the product was taken out of the reaction vessel for chromatographic analysis.

[0110] Analysis revealed that the conversion rate of p-nitrochlorobenzene was 100%, and the selectivity of p-chloroaniline was greater than 99%.

[0111] Application Example 3

[0112] 100 mg of carbon-coated metal catalyst A3, 316 mg of p-nitrochlorobenzene, 27 mL of isopropanol, and 3 mL of water were added to a reaction vessel. After purging the reaction vessel with H2 three times, the mixture was stirred and heated under low pressure until the predetermined reaction temperature of 80 °C was reached. H2 was then introduced again to bring the pressure inside the reaction vessel to 1 MPa. The reaction was continued for 120 minutes, after which heating was stopped. The mixture was cooled to room temperature and the pressure was released. The product was then opened and subjected to chromatographic analysis.

[0113] Analysis revealed that the conversion rate of p-nitrochlorobenzene was 100%, and the selectivity of p-chloroaniline was greater than 99%.

[0114] Application Example 4

[0115] 80 mg of carbon-coated metal catalyst A4, 316 mg of p-nitrochlorobenzene, 27 mL of isopropanol, and 3 mL of water were added to a reaction vessel. After purging the reaction vessel with H2 three times, the mixture was stirred and heated under low pressure until the predetermined reaction temperature of 80 °C was reached. H2 was then introduced again to bring the pressure inside the reaction vessel to 1 MPa. The reaction was continued for 120 minutes, after which heating was stopped. The mixture was cooled to room temperature and the pressure was released. The product was then opened and subjected to chromatographic analysis.

[0116] Analysis revealed that the conversion rate of p-nitrochlorobenzene was 79%.

[0117] Application Example 5

[0118] Following the method of Application Example 1, except that an equal mass of carbon-coated metal catalyst A5 was used instead of A1. After the reaction was continued for 90 minutes, heating was stopped, the mixture was cooled to room temperature, the pressure was released, and the product was taken out of the reactor for chromatographic analysis.

[0119] Analysis revealed a 100% conversion rate for p-nitrochlorobenzene and a 99% selectivity for p-chloroaniline. However, the catalyst reverted to powder form after the experiment and could not be reused.

[0120] Comparative Application Example 1

[0121] Following the method of Application Example 1, except that an equal mass of the molding catalyst DA1 was used to replace A1. After the reaction was continued for 120 minutes, heating was stopped, the mixture was cooled to room temperature, the pressure was released, and the product was taken out of the reactor for chromatographic analysis.

[0122] Analysis revealed that the conversion rate of p-nitrochlorobenzene was 0%.

[0123] Comparative Application Example 2

[0124] Following the method of Application Example 1, except that an equal mass of the molding catalyst DA2 was used instead of A1. After reacting for 90 minutes, heating was stopped, the mixture was allowed to cool to room temperature, the pressure was released, and the product was removed from the reactor for chromatographic analysis.

[0125] Analysis revealed that the conversion rate of p-nitrochlorobenzene was 0%.

[0126] The comparison of the above examples and comparative examples shows that the present invention utilizes coal tar heat treatment to shape a carbon-coated metal catalyst, which is then applied to the selective hydrogenation of chloroaromatic nitro compounds to prepare chloroaromatic amines. Under mild reaction conditions, the conversion rate of chloroaromatic nitro compounds can reach 100%, and the selectivity of chloroaromatic amines can reach over 99%. Furthermore, it exhibits good compressive strength, suitable specific surface area, and pore size. The shaped catalysts prepared in Comparative Examples 1 and 2 are difficult to exert catalytic activity, with a conversion rate of essentially 0 for nitrochlorobenzene. This may be because the calcination temperature of Comparative Example 1 is too high, leading to catalyst deactivation, and the use of alumina as a binder in Comparative Example 2 may result in the catalyst matrix being completely encapsulated, making it difficult to exert catalytic activity in the catalytic hydrogenation reaction of chloroaromatic nitro compounds.

[0127] 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 combinations of 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. A method for preparing a shaped catalyst, the method comprising: The catalyst matrix, coal tar and first solvent are mixed, and then shaped and calcined. The temperature of the molding and baking process shall not exceed 500℃; The catalyst matrix comprises transition metal particles and a graphitized carbon layer shell covering the surface of the transition metal particles.

2. The preparation method according to claim 1, wherein, The mass ratio of coal tar to catalyst matrix is ​​(0.1-0.5):1, preferably (0.3-0.5):1; Preferably, the mass ratio of the first solvent to the catalyst matrix is ​​(0.01-0.1):1, more preferably (0.01-0.05):1; Preferably, the first solvent is water.

3. The preparation method according to claim 1 or 2, wherein, No additional binder is introduced into the mixture.

4. The preparation method according to any one of claims 1-3, wherein, The forming method is extrusion molding; Preferably, the molding and calcining temperature is 200-500℃, more preferably 280-390℃, and the time is 0.5-5h, more preferably 1-3h; Preferably, the molding and calcination are carried out under a protective atmosphere, which is preferably provided by nitrogen and / or argon.

5. The preparation method according to any one of claims 1-4, wherein, The method for preparing the catalyst matrix includes: (1) A homogeneous solution is obtained by mixing a transition metal source, a polycarboxylic acid, and a second solvent; (2) Remove the second solvent from the homogeneous solution to obtain the precursor; (3) The precursor is heat-treated in an inert atmosphere and / or a reducing atmosphere.

6. The preparation method according to claim 5, wherein, The transition metal source is selected from at least one of the hydroxides, oxides, carbonates and acetates of transition metals; Preferably, the transition metal is nickel; Preferably, the polycarboxylic acid is selected from at least one of ethylenediaminetetraacetic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, 1,3-propanediaminetetraacetic acid, citric acid, maleic acid, trimesic acid, terephthalic acid, and malic acid.

7. The preparation method according to claim 5 or 6, wherein, The molar ratio of the transition metal source (calculated as metal element) to the polycarboxylic acid (calculated as carboxyl group) is 1:(2-12), preferably 1:(4-9); Preferably, the heat treatment conditions include: a temperature of 280-600℃, a time of 60-180 min, and a heating rate of 0.2-10℃ / min.

8. The shaped catalyst prepared by the method according to any one of claims 1-7; Preferably, the pore volume of the molded catalyst is 0.05-0.15 cm³. 3 / g; Preferably, the specific surface area of ​​the shaped catalyst is 15-40 m². 2 / g; Preferably, the side crushing strength of the shaped catalyst is 60-120 N / cm.

9. A method for the catalytic hydrogenation of a chlorinated aromatic nitro compound, the method comprising: Under hydrogenation reaction conditions, chlorinated aromatic nitro compounds are contacted with a catalyst; The catalyst is characterized in that it is the molding catalyst as described in claim 8.

10. The method according to claim 9, wherein, The hydrogenation reaction conditions include: a reaction temperature of 40-200℃, a hydrogen pressure of 0.5-5MPa, and a mass ratio of catalyst to chlorinated aromatic nitro compound of 1:(1-500). Preferably, the contact is carried out in the presence of a third solvent, which is preferably at least one of methanol, ethanol, water, isopropanol, and tetrahydrofuran.

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