Preparation method and application of Pt-cAn / C@C hydrogenation catalyst with good sulfur resistance

Abstract

The present invention discloses a preparation method and application of a Pt‑cAn / C@C hydrogenation catalyst with good sulfur resistance. The preparation method of the Pt‑cAn / C@C hydrogenation catalyst is implemented according to the following steps: (1) activated carbon pretreatment; (2) mixing: Pt precursor, excess aniline and activated carbon are completely mixed, then purified with nitrogen for 10‑60 min, and the mixture is stirred for 12‑48 h until the formation of the pt‑aniline complex is completed; (3) filtering to obtain a Pt‑An / C sample; (4) calcining to obtain a Pt‑cAn / C product; (5) carbon coating to obtain a Pt‑cAn / C@C catalyst. The present invention provides an application of the prepared Pt‑cAn / C@C catalyst in the preparation of halogenated aniline by catalytic hydrogenation of halogenated nitrobenzene, which can significantly improve the hydrogenation performance and the sulfur poisoning resistance of the catalyst.

Description

Technical Field

[0001] The present invention relates to the field of catalyst technology, and in particular to a preparation method and application of a Pt-cAn / C@C hydrogenation catalyst with good sulfur resistance. Background Art

[0002] Precious metal catalysts are used in catalytic reactions involving sulfur-containing compounds, which are naturally occurring in hydrocarbons and are therefore found in industrial raw materials. Thioproducts, such as mercaptans, sulfides, polysulfides, sulfur species, sulfuric acid, and thioesters, are increasingly used in the industrial production of pharmaceuticals, pesticides, cosmetics, and petrochemicals. Precious metal catalysts readily adsorb sulfur, forming compounds that can reduce or even deactivate their catalytic activity. Developing catalysts that allow precious metal catalysts to participate in reactions involving sulfur-containing compounds without experiencing a decrease in activity or deactivation is of great research interest.

[0003] In industrial production, sulfur impurities mainly exist in the form of organic sulfur and inorganic sulfur. In liquid-phase hydrogenation, sulfur impurities are often mainly in the form of organic sulfur. Among them, low-valent sulfides such as disulfides, thiols and their derivatives have the strongest poisoning effect on precious metal catalysts. Concentrations at the ppm level can lead to reduced activity or even inactivation of precious metal catalysts.

[0004] Currently, in production applications, low or even complete catalyst deactivation caused by sulfur impurities, as well as the difficulty in recovering catalytic activity, are serious obstacles to the industrialization of many catalytic processes. Sulfur-containing molecules have the potential for strong chemical adsorption, and can chemically adsorb onto active metals, covering active centers (or undergo dissociative adsorption on the metal, with the reduced sulfur forming a strong bond with the precious metal), leading to catalyst deactivation. Under harsh conditions, sulfur atoms can even gradually enter the active metal phase, forming crystalline phases such as sulfide salts. The formation of these sulfide crystals can, to some extent, further reduce the activity of the catalyst.

[0005] To avoid this, precious metal hydrogenation catalysts must effectively inhibit the process of sulfur components occupying precious metal active sites while maintaining hydrogenation activity. This requires targeted research on the structure of precious metal hydrogenation catalysts to weaken the interaction between precious metal active components and sulfur components, focusing on reducing the ability of sulfur-containing components to adsorb on precious metals, thereby protecting the precious metal active sites and maintaining their activity towards hydrogenation groups, making them more resistant to sulfur and thus extending their service life. Such precious metal hydrogenation catalysts with excellent sulfur resistance have extremely broad market prospects in the fields of energy and chemical engineering, fine chemicals, and environmental protection. Summary of the Invention

[0006] The purpose of the present invention is to overcome and supplement the deficiencies in the prior art, provide a method for preparing a noble metal liquid-phase hydrogenation catalyst with good sulfur resistance and its application in the catalytic hydrogenation of halonitrobenzenes to prepare halogenated anilines, thereby improving the hydrogenation performance and the sulfur poisoning resistance of the catalyst.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a Pt-cAn / C@C hydrogenation catalyst, which is implemented according to the following steps:

[0009] (1) Activated carbon pretreatment: Activated carbon and a 3% to 20% nitric acid aqueous solution are placed in a container, stirred, and heated at 50-100°C for 6-24 hours. The surface-treated activated carbon is washed with deionized water several times until it becomes neutral, and then placed in a forced air drying oven heated to 80-130°C for dehydration for 6-12 hours.

[0010] (2) Mixing: Pt precursor (H2PtCl6〃6H2O), excess aniline and activated carbon are thoroughly mixed, then purged with nitrogen for 10-60 minutes, and the mixture is stirred for 12-48 hours until the formation of the Pt-aniline complex is complete;

[0011] (3) Filtration: Centrifuging the reaction mixture obtained in step (2), and filtering to obtain a Pt-An / C sample;

[0012] (4) Calcination: The Pt-An / C sample obtained in step (3) is then placed in a forced air drying oven heated to 80-130°C for dehydration for 6-12 hours. The dried sample is then calcined in a nitrogen atmosphere in a tube furnace at a calcination temperature of 400-800°C for a holding time of 2-6 hours to complete the carbonization of the Pt-aniline complex. The Pt-An / C product is collected after cooling.

[0013] (5) Carbon coating: Deionized water and a carbon source are added to a stainless steel autoclave lined with polytetrafluoroethylene, and the mixture is stirred at room temperature for 10-60 minutes to fully disperse the carbon source in the deionized water; the prepared Pt-cAn / C product is put into the stainless steel autoclave, and the autoclave is then sealed and placed in an oil bath, heated to 120-240°C with stirring and maintained for 12-48 hours to fully mix; the mixture is then filtered, and the filtered solid is placed in a forced air drying oven heated to 80-130°C and dehydrated for 6-12 hours; the dried product is placed in a tubular furnace in a nitrogen atmosphere and calcined at a calcination temperature of 300°C-600°C for 2-6 hours, and then reduced with hydrogen at 300°C-600°C for 2-6 hours in a hydrogen atmosphere, and cooled to obtain a Pt-cAn / C@C catalyst.

[0014] Preferably, in step (1), the activated carbon is a type of coal-based activated carbon, the activated carbon is powdered microporous activated carbon, and the activated carbon parameters are: specific surface area 800-1400m 2 / g, pore volume 0.6-1.0cm3 / g, average pore diameter 1.9-2.3nm.

[0015] Preferably, in step (1), the mass fraction of nitric acid in the nitric acid aqueous solution is 5%.

[0016] In step (2), the precious metal precursor is fed according to the mass fraction of the precious metal in the catalyst, and the mass fraction of the precious metal in the catalyst is calculated according to the following formula: mass fraction of precious metal in the catalyst = mass of precious metal in precious metal precursor / (mass of precious metal in precious metal precursor + mass of activated carbon) * 100%. Preferably, the mass fraction of precious metal Pt in the catalyst is 1-5%.

[0017] Preferably, in step (2), the feed ratio of Pt precursor (H2PtCl6〃6H2O) to aniline is 1g:50-300mL.

[0018] Preferably, in step (5), the carbon source is at least one of glucose, sucrose, graphite powder, corn starch, and chitosan. The amount of carbon source added in step (5) is related to the carbon coating ratio. The specific amount of carbon source added is calculated according to the following formula: ①, carbon coating ratio = mass of required C / (amount of Pt-cAn / C catalyst + mass of required C); ②, mass of required C / mass of required carbon source = relative atomic mass of required C in the carbon source / relative atomic mass of the carbon source. Preferably, the carbon coating ratio is 5%-50%.

[0019] Preferably, in step (1) or (4) or (5), the temperature in the blast drying oven is set to 110° C., and the heating time is 10 h.

[0020] Preferably, in step (1), the stirring temperature is 80° C. and the heating is performed for 12 h.

[0021] Preferably, in step (2), nitrogen purification is performed for 30 minutes; and the mixture is stirred for 24 hours.

[0022] Preferably, in step (4), the calcination temperature is 600° C. and the holding time is 4 hours.

[0023] Preferably, in step (4), the heating rate of the calcination process is 2-10°C / min.

[0024] Preferably, in step (5), stirring is performed at room temperature for 30 minutes; the autoclave is sealed and placed in an oil bath, and heated to 180°C for 24 hours under stirring; the dried catalyst is calcined at 450°C in a nitrogen atmosphere in a tubular furnace for 4 hours, and then reduced with hydrogen at 450°C for 2 hours under a hydrogen atmosphere.

[0025] In a second aspect, the present invention provides use of the Pt-cAn / C@C catalyst prepared as described above in the catalytic hydrogenation of halogenated nitrobenzenes to prepare halogenated anilines.

[0026] In particular, the halogenated nitrobenzene catalytic hydrogenation reaction system contains sulfur impurities. In a specific embodiment of the present invention, the halogenated nitrobenzene is o-chloronitrobenzene.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The Pt-cAn / C@xC catalyst synthesized in this invention has a unique structure, consisting of platinum nanoparticles coated with carbonized aniline, which is then coated with a layer of carbon. This unique structure reduces the strong adsorption of sulfur, and the carbon layer successfully prevents the growth of platinum nanoparticles through aggregation and Ostwald ripening, thereby improving durability. Compared to traditional Pt / C catalysts, this catalyst exhibits superior activity and stability in terms of resistance to sulfur impurities. DETAILED DESCRIPTION

[0029] The present invention is described below with reference to specific examples. It should be noted that the examples are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention.

[0030] The activated carbon used in the present invention is powdered microporous activated carbon, and the activated carbon parameters are: specific surface area 854m2 / g, pore volume 0.609cm3 / g, average pore diameter 1.92nm. The glucose used is glucose monohydrate. The molecular formula of corn starch is (C6H 10 O5) n .

[0031] Example 1

[0032] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% aqueous nitric acid solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven at 110°C for 10 h.

[0033] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 3.7274 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0034] (3) Filtration: The mixture was then centrifuged using a centrifuge and filtered through filter paper (cellulose paper).

[0035] (4) Calcination: The filtered sample (1 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then calcined in a tube furnace in a nitrogen atmosphere, starting at 30°C and increasing the temperature to 600°C at a rate of 3°C / min for 4 hours to complete carbonization of the Pt-aniline complex. The product (1 wt% Pt-An / C) was collected after cooling.

[0036] (5) Carbon coating: 150 ml of deionized water was added to a 250 ml polytetrafluoroethylene-lined stainless steel autoclave. 0.3085 g of glucose was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse the mixture in the deionized water. 1 g of the prepared 1 wt% Pt-cAn / C catalyst was placed in a stainless steel reactor. The autoclave was then sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to fully mix the mixture. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere at an initial temperature of 30°C and a rate of 3°C / min to 450°C, maintained for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (1 wt% Pt-cAn / C@10%C) was collected after cooling.

[0037] Example 2

[0038] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% nitric acid aqueous solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven heated to 110°C for 10 h.

[0039] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 1.2174 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0040] (3) Filtration: The mixture was then centrifuged and filtered through filter paper (cellulose paper).

[0041] (4) Calcination: The filtered sample (3 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then centrifugally calcined in a nitrogen atmosphere in a tube furnace starting at 30°C at a rate of 3°C / min to 600°C, where it was held for 4 hours to complete carbonization of the Pt-aniline complex. The product (3 wt% Pt-cAn / C) was collected after cooling.

[0042] (5) Carbon coating: 150 ml of deionized water was added to a 250 ml polytetrafluoroethylene-lined stainless steel autoclave. 0.3085 g of glucose was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse it in the deionized water. 1 g of the prepared 3 wt% Pt-cAn / C catalyst was placed in a stainless steel reactor. The autoclave was then sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to fully mix the mixture. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere at an initial temperature of 30°C and a rate of 3°C / min to 450°C, maintained for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (3 wt% Pt-cAn / C@10%C) was collected after cooling.

[0043] Example 3

[0044] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% nitric acid aqueous solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven heated to 110°C for 10 h.

[0045] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 0.9036 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0046] (3) Filtration: The mixture was then centrifuged and filtered through filter paper (cellulose paper).

[0047] (4) Calcination: The filtered sample (4 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then centrifugally calcined in a nitrogen atmosphere in a tube furnace starting at 30°C at a rate of 3°C / min to 600°C, where it was held for 4 hours to complete carbonization of the Pt-aniline complex. The product (4 wt% Pt-cAn / C) was collected after cooling.

[0048] (5) Carbon coating: 150 ml of deionized water was added to a 250 ml polytetrafluoroethylene-lined stainless steel autoclave. 0.3085 g of glucose was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse the mixture in the deionized water. 1 g of the prepared 4 wt% Pt-cAn / C catalyst was placed in a stainless steel reactor. The autoclave was then sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to fully mix the mixture. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere at an initial temperature of 30°C and a rate of 3°C / min to 450°C, maintained for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (4 wt% Pt-cAn / C@10%C) was collected after cooling.

[0049] Example 4

[0050] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% nitric acid aqueous solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven heated to 110°C for 10 h.

[0051] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 0.7154 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0052] (3) Filtration: The mixture was then centrifuged and filtered through filter paper (cellulose paper).

[0053] (4) Calcination: The filtered sample (5 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then centrifugally calcined in a nitrogen atmosphere in a tube furnace starting at 30°C at a rate of 3°C / min to 600°C, where it was held for 4 hours to complete carbonization of the Pt-aniline complex. The product (5 wt% Pt-cAn / C) was collected after cooling.

[0054] (5) Carbon coating: 150 ml of deionized water was added to a 250 ml polytetrafluoroethylene-lined stainless steel autoclave. 0.3085 g of glucose was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse it in the deionized water. 1 g of the prepared 5 wt% Pt-cAn / C catalyst was placed in a stainless steel reactor. The autoclave was then sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to fully mix the mixture. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere at an initial temperature of 30°C and a rate of 3°C / min to 450°C, maintained for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (5 wt% Pt-cAn / C@10%C) was collected after cooling.

[0055] Example 5

[0056] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% nitric acid aqueous solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven heated to 110°C for 10 h.

[0057] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 1.2174 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0058] (3) Filtration: The mixture was then centrifuged and filtered through filter paper (cellulose paper).

[0059] (4) Calcination: The filtered sample (3 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then centrifugally calcined in a nitrogen atmosphere in a tube furnace starting at 30°C at a rate of 3°C / min to 600°C, where it was held for 4 hours to complete carbonization of the Pt-aniline complex. The product (3 wt% Pt-cAn / C) was collected after cooling.

[0060] (5) Carbon coating: 150 ml of deionized water was added to a 250 ml polytetrafluoroethylene-lined stainless steel autoclave. 1.1797 g of glucose was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse it in the deionized water. 1 g of the prepared 3 wt% Pt-cAn / C catalyst was placed in a stainless steel reactor. The autoclave was then sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to fully mix the mixture. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere at an initial temperature of 30°C and a rate of 3°C / min to 450°C, maintained for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (3 wt% Pt-cAn / C@30%C) was collected after cooling.

[0061] Example 6

[0062] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% nitric acid aqueous solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven heated to 110°C for 10 h.

[0063] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 1.2174 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0064] (3) Filtration: The mixture was then centrifuged and filtered through filter paper (cellulose paper).

[0065] (4) Calcination: The filtered sample (3 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then centrifugally calcined in a nitrogen atmosphere in a tube furnace starting at 30°C at a rate of 3°C / min to 600°C, where it was held for 4 hours to complete carbonization of the Pt-aniline complex. The product (3 wt% Pt-cAn / C) was collected after cooling.

[0066] (5) Carbon coating: 150 ml of deionized water was added to a 250 ml polytetrafluoroethylene-lined stainless steel autoclave. 2.7524 g of glucose was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse it in the deionized water. 1 g of the prepared 3 wt% Pt-cAn / C catalyst was placed in a stainless steel reactor. The autoclave was then sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to fully mix the mixture. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere at an initial temperature of 30°C and a rate of 3°C / min to 450°C, maintained for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (3 wt% Pt-cAn / C@50%C) was collected after cooling.

[0067] Example 7

[0068] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% nitric acid aqueous solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven heated to 110°C for 10 h.

[0069] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 1.2174 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0070] (3) Filtration: The mixture was then centrifuged and filtered through filter paper (cellulose paper).

[0071] (4) Calcination: The filtered sample (3 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then centrifugally calcined in a nitrogen atmosphere in a tube furnace starting at 30°C at a rate of 3°C / min to 600°C, where it was held for 4 hours to complete carbonization of the Pt-aniline complex. The product (3 wt% Pt-cAn / C) was collected after cooling.

[0072] (5) Carbon coating: 150 ml of deionized water was added to a 250 ml polytetrafluoroethylene-lined stainless steel autoclave. 0.1449 g of glucose was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse it in the deionized water. 1 g of the prepared 3 wt% Pt-cAn / C catalyst was placed in a stainless steel reactor. The autoclave was then sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to fully mix the mixture. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere at an initial temperature of 30°C and a rate of 3°C / min to 450°C, maintained for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (3 wt% Pt-cAn / C@5%C) was collected after cooling.

[0073] Example 8

[0074] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% nitric acid aqueous solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven heated to 110°C for 10 h.

[0075] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 1.2174 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0076] (3) Filtration: The mixture was then centrifuged and filtered through filter paper (cellulose paper).

[0077] (4) Calcination: The filtered sample (3 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then centrifugally calcined in a nitrogen atmosphere in a tube furnace starting at 30°C at a rate of 3°C / min to 600°C, where it was held for 4 hours to complete carbonization of the Pt-aniline complex. The product (3 wt% Pt-cAn / C) was collected after cooling.

[0078] (5) Carbon coating: 150 ml of deionized water was added to a 250 ml polytetrafluoroethylene-lined stainless steel autoclave. 0.2636 g of sucrose was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse it in the deionized water. 1 g of the prepared 3 wt% Pt-cAn / C catalyst was placed in a stainless steel reactor. The autoclave was then sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to fully mix the mixture. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere at an initial temperature of 30°C and a rate of 3°C / min to 450°C, maintained for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (3 wt% Pt-cAn / C@10%C) was collected after cooling.

[0079] Example 9

[0080] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% nitric acid aqueous solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven heated to 110°C for 10 h.

[0081] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 1.2174 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0082] (3) Filtration: The mixture was then centrifuged and filtered through filter paper (cellulose paper).

[0083] (4) Calcination: The filtered sample (3 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then centrifugally calcined in a nitrogen atmosphere in a tube furnace starting at 30°C at a rate of 3°C / min to 600°C, where it was held for 4 hours to complete carbonization of the Pt-aniline complex. The product (3 wt% Pt-cAn / C) was collected after cooling.

[0084] (5) Carbon coating: 150 ml of deionized water was added to a 250 ml polytetrafluoroethylene-lined stainless steel autoclave. 0.2487 g of chitosan was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse it in the deionized water. 1 g of the prepared 3 wt% Pt-cAn / C catalyst was placed in a stainless steel reactor. The autoclave was then sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to fully mix the mixture. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere at an initial temperature of 30°C and a rate of 3°C / min to 450°C, maintained for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (3 wt% Pt-cAn / C@10%C) was collected after cooling.

[0085] Example 10

[0086] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% nitric acid aqueous solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven heated to 110°C for 10 h.

[0087] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 1.2174 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0088] (3) Filtration: The mixture was then centrifuged and filtered through filter paper (cellulose paper).

[0089] (4) Calcination: The filtered sample (3 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then centrifugally calcined in a nitrogen atmosphere in a tube furnace starting at 30°C at a rate of 3°C / min to 600°C, where it was held for 4 hours to complete carbonization of the Pt-aniline complex. The product (3 wt% Pt-cAn / C) was collected after cooling.

[0090] (5) Carbon coating: 150 ml of deionized water was added to a 250 ml polytetrafluoroethylene-lined stainless steel autoclave. 0.2500 g of corn starch was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse the mixture in the deionized water. 1 g of the prepared 3 wt% Pt-cAn / C catalyst was placed in a stainless steel reactor. The autoclave was then sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to fully mix the mixture. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere at an initial temperature of 30°C and a rate of 3°C / min to 450°C, maintained for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (3 wt% Pt-cAn / C@10%C) was collected after cooling.

[0091] The catalyst activity and selectivity of the prepared catalyst were evaluated according to the following method:

[0092] Reaction conditions: To a 250ml batch reactor, add 10.5ml of o-chloronitrobenzene, 0.25g of the above-prepared catalyst, 140ml of anhydrous ethanol as solvent, and 600μl of n-dodecanethiol. Control the reaction temperature at 75°C, the hydrogen pressure at 0.8-1.2MPa, and the rotation speed at 1000pm to produce o-chloroaniline.

[0093] The evaluation results of the catalyst are shown in Table 1 below.

[0094] Table 1 Evaluation results of o-chloronitrobenzene catalytic hydrogenation reaction over Pt-cAn / C@xC catalyst

[0095]

[0096] Comparative Example 1

[0097] Commercial 3 wt% Pt / C (Degong Chemical Co., Ltd.) without any treatment.

[0098] Comparative Example 2

[0099] (1) Activated carbon pretreatment: 2 g of coal-based activated carbon was added to 50 mL of a 5 wt% nitric acid aqueous solution and heated to 80°C for 12 h. The surface-treated activated carbon was washed several times with deionized water until it became neutral (pH 7.0) and then dehydrated in a forced air drying oven heated to 110°C for 10 h.

[0100] (2) Mixing: 0.1 g of Pt precursor (HPtCl6"6H2O), 10 ml of aniline, and 1.2174 g of activated carbon (after pretreatment) were thoroughly mixed and then purged with nitrogen for 30 min. The mixture was stirred for 24 h until the formation of the Pt-aniline complex was complete.

[0101] (3) Filtration: The mixture was then centrifuged and filtered through filter paper (cellulose paper).

[0102] (4) Calcination: The filtered sample (3 wt% Pt-An / C) was then dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was then centrifugally calcined in a nitrogen atmosphere in a tube furnace starting at 30°C at a rate of 3°C / min to 600°C, where it was held for 4 hours to complete carbonization of the Pt-aniline complex. The product (3 wt% Pt-cAn / C) was collected after cooling.

[0103] Comparative Example 3

[0104] Commercial 3 wt% Pt / C coated carbon: 150 ml of deionized water was added to a 250 ml Teflon-lined stainless steel autoclave. 0.3058 g of glucose was weighed and added to the deionized water. The mixture was stirred at room temperature for 30 min to fully disperse the glucose in the deionized water. 1 g of commercial 3 wt% Pt / C catalyst was placed in a stainless steel reactor. The autoclave was sealed and placed in an oil bath. The mixture was heated to 180°C with stirring for 24 h to allow for thorough mixing. The mixture was then filtered using a solvent filter. The catalyst was dehydrated in a forced-air drying oven at 110°C for 10 h. The dried catalyst was heated in a tube furnace in a nitrogen atmosphere from an initial temperature of 30°C at a rate of 3°C / min to 450°C, held for 4 h, and then reduced in a hydrogen atmosphere at 450°C for 2 h. The product (3 wt% Pt / C @ 10% C) was collected after cooling.

[0105] The evaluation methods for catalyst activity and selectivity are the same as above. The evaluation results of different catalysts are shown in Table 2 below.

[0106] Table 2 Reaction evaluation results of different types of catalysts

[0107]

[0108] The catalyst activity and selectivity evaluation method is the same as above. Different catalysts are applied, and 5% of the catalyst mass of the first reaction catalyst is added each time. The evaluation results are shown in Table 3 below.

[0109] Table 3 Reaction evaluation results of different types of catalysts

[0110]

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a Pt-cAn / C@C hydrogenation catalyst, characterized in that: The preparation method is implemented according to the following steps: (1) Activated carbon pretreatment: Activated carbon and a 3%-20% nitric acid aqueous solution are placed in a container, stirred and heated at 50-100°C for 6-24 hours. The surface-treated activated carbon is washed with deionized water for multiple times until it becomes neutral, and then placed in a forced air drying oven heated to 80-130°C for dehydration for 6-12 hours. (2) Mixing: Pt precursor, aniline and activated carbon are mixed thoroughly, with the feed ratio of Pt precursor to aniline being 1 g:50-300 mL, and then purged with nitrogen for 10-60 min, and the mixture is stirred for 12-48 h until the formation of the Pt-aniline complex is complete; (3) Filtration: centrifuging the reaction mixture obtained in step (2), and filtering to obtain a Pt-An / C sample; (4) Calcination: The Pt-An / C sample obtained in step (3) is then placed in a forced air drying oven heated to 80-130° C. for dehydration for 6-12 hours, and then the dried sample is calcined in a nitrogen atmosphere in a tubular furnace at a calcination temperature of 400° C.-800° C. for a holding time of 2-6 hours to complete the carbonization of the Pt-aniline complex, and the Pt-cAn / C product is collected after cooling; (5) Carbon coating: deionized water and a carbon source are added to a stainless steel autoclave with a polytetrafluoroethylene liner, and the mixture is stirred at room temperature for 10-60 minutes to fully disperse the carbon source in the deionized water; the prepared Pt-cAn / C product is put into the stainless steel autoclave, and the autoclave is then sealed and placed in an oil bath, heated to 120-240°C with stirring and maintained for 12-48 hours to fully mix the product; the product is then filtered, and the solid obtained by filtration is placed in a forced air drying oven heated to 80-130°C and dehydrated for 6-12 hours; the dried product is placed in a tubular furnace in a nitrogen atmosphere and calcined at a calcination temperature of 300°C-600°C for 2-6 hours, and then reduced with hydrogen at 300°C-600°C for 2-6 hours in a hydrogen atmosphere, and the Pt-cAn / C@C catalyst is obtained after cooling.

2. The preparation method according to claim 1, characterized in that: In the step (1), the activated carbon is powdered microporous activated carbon, and the activated carbon parameters are: specific surface area 800-1400 m 2 / g, pore volume 0.6-1.0 cm 3 / g, average pore size 1.9-2.3 nm.

3. The preparation method according to claim 1, characterized in that: In the step (1), the mass fraction of nitric acid in the nitric acid aqueous solution is 5%.

4. The preparation method according to claim 1, characterized in that: In the step (2), the precious metal precursor is fed according to the mass fraction of the precious metal in the catalyst, and the mass fraction of the precious metal in the catalyst is calculated according to the following formula: mass fraction of the precious metal in the catalyst = mass of the precious metal in the precious metal precursor / (mass of the precious metal in the precious metal precursor + mass of activated carbon)*100%; the mass fraction of the precious metal Pt in the catalyst is 1-5%.

5. The preparation method according to claim 1, characterized in that: In the step (2), the Pt precursor is (H2PtCl6·6H2O), and the feed ratio of the Pt precursor to aniline is 1g:50-300mL.

6. The preparation method according to claim 1, characterized in that: In the step (5), the carbon source is at least one of glucose, sucrose, graphite powder, corn starch and chitosan.

7. The preparation method according to claim 1 or 6, characterized in that: In step (5), the amount of carbon source added is calculated according to the following formula: ①, carbon encapsulation ratio = mass of required C / (amount of Pt-cAn / C product + mass of required C); ②, mass of required C / mass of required carbon source = relative atomic mass of required C in carbon source / relative atomic mass of carbon source; the carbon encapsulation ratio is 5%-50%.

8. Use of the Pt-cAn / C@C catalyst prepared according to the preparation method of claim 1 in the catalytic hydrogenation of halogenated nitrobenzene to prepare halogenated aniline.

9. The use according to claim 8, characterized in that: The halogenated nitrobenzene catalytic hydrogenation reaction system contains sulfur impurities.

10. The use according to claim 8 or 9, characterized in that: The halogenated nitrobenzene is o-chloronitrobenzene.

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