Multifunctional copper-based composite catalyst and preparation method and application thereof

Abstract

The invention discloses a multifunctional copper-based composite catalytic material and a preparation method and application thereof, urea, boric acid and barbituric acid are respectively used as a nitrogen source, a boron source and a carbon source, phthalocyanine is used as a complexing agent, Cu (NO3) 2.6 H2O is used as a metal source, and the multifunctional copper-based composite material with an interspersed two-dimensional nanosheet structure is obtained through heating, stirring, drying, grinding, calcining and the like. The preparation method is simple in synthesis process, high-dispersion Cu metal is modified and loaded on the carbon carrier by constructing a strong covalent coordination effect between a central metal single atom and surrounding coordination atoms and utilizing a Cu-N chemical bond bonding effect, and regulation and optimization of an electronic structure and steric hindrance of the catalyst are realized. The obtained catalytic material can efficiently show high catalytic activity in H2S high-valued reaction catalysis, is not prone to inactivation due to sulfur poisoning, can be recycled, is wide in substrate applicability and large in industrial application prospect, and has important significance.

Description

Technical Field

[0001] The present invention belongs to the technical field of material preparation and environmental catalysis, and particularly relates to a multifunctional copper-based composite catalyst, a preparation method thereof and an application thereof. Background Art

[0002] H2S is a typical inorganic sulfur gas with a colorless and pungent "rotten egg" odor, and has extremely strong toxicity, corrosiveness, flammability and explosiveness. A large amount of H2S gas is emitted in industrial processes such as crude oil hydrogenation, coal and biomass gasification, natural gas processing, sewage treatment and landfill. H2S existing in gaseous or liquid form will not only corrode pipelines and equipment, but also cause harm to the health of humans, animals and plants. In addition, H2S present in the atmosphere will be oxidized into SO2, which will further cause acid rain and haze pollution. The Claus process is a mature process for recovering sulfur by oxidizing H2S. The reaction process is restricted by thermodynamics, so there is still 3%-5% of H2S remaining in the tail gas. On the other hand, this process can only catalytically convert H2S into elemental sulfur with relatively low added value, and the hydrogen-containing element is converted into H2O and discharged as wastewater, which not only pollutes the environment, but also wastes a large amount of valuable hydrogen resources. Therefore, there is an urgent need to develop a green new technology for atomically economical utilization of H2S and realize its clean and highly valuable utilization. If H2S is used as a raw material for both hydrogen and sulfur at the same time, a new chemical reaction system and a suitable new type of high-efficiency catalyst are constructed to efficiently utilize each atom in H2S to synthesize high-added-value chemicals, and simultaneously realize the efficient removal of H2S and the highly valuable utilization of H2S. The key to implementing this idea lies in constructing a new and effective chemical reaction system and designing and synthesizing a stable and high-efficiency catalyst.

[0003] Thioamides and their derivatives are widely used in the fields of organic and pharmaceutical chemistry. Such compounds mainly exist in heterocyclic compounds, natural products and bioactive compounds. In addition, it is also an important industrial raw material and pharmaceutical intermediate with high application value. At present, several schemes for obtaining thioamide compounds have been reported, including the Willgerodt-Kindler (WK) reaction, the reaction between amides and phosphorus pentasulfide or Lawesson's reagent, the reaction between alcohols and sulfur sources, and the three-component reaction system composed of carboxylic acids, sulfur and amines, but the reaction yields are low. Using H2S as a "sulfur donor" and a "hydrogen donor", and through a chemical conversion reaction with aryl nitrile groups, a new process route for atomically economical utilization of H2S to synthesize thioamide chemicals with high chemical value, and efficiently removing H2S from the source and highly valuable utilization of H2S has potential application value. And how to construct a catalyst system with new structures and high performance has become the key to the atomic economical utilization and highly valuable utilization of H2S.

[0004] Numerous metal oxides and carbon materials have been applied as catalysts for H2S catalytic conversion. However, the strong oxidizing property of conventional metal oxide materials easily promotes the formation of sulfates in the reaction system, leading to the deactivation of the catalyst due to salt deposition on the catalyst surface. Non-metal catalysts represented by carbon-based catalysts have low intrinsic activity in the H2S catalytic reaction, which is not conducive to the resource utilization of H2S. It is worth mentioning that B and N can form strong covalent bonds with C, thus generating boron-doped carbon nitride materials with light mass and thermodynamic stability. There are four chemical bonds, namely C-N, B-N, B-B, and B-C, in the BCN framework, which is conducive to electron transfer. In addition, the unique properties of BCN can serve as a good support material. The introduction of N is likely to cause lattice distortion and increase active sites, which is beneficial to the adsorption and activation of reaction molecules. More importantly, N can serve as an anchoring point for metals to form strongly coupled M-Nx centers. As a transition metal element, Cu has a unique electronic structure with multiple valence states such as 0, +1, and +2. Copper in different valence states plays different roles in different catalytic reactions, providing more possibilities for the design and regulation of catalysts. Therefore, how to optimize the preparation process of the BCN-supported metal catalyst, make the supported metal disperse evenly, and form metal-N or metal-B coordination bonds to anchor the metal, so as to obtain a Cu / BCN composite material with unique structural and electronic properties, making it have excellent physical and chemical properties such as nucleophilicity, Lewis / Bronsted basicity, adsorption and activation of various small molecules, etc., is an urgent problem to be solved. Summary of the Invention

[0005] Aiming at the deficiencies of traditional desulfurization methods, the present invention provides a synthesis method and application of an atomically dispersed Cu metal catalytic material supported on BCN, which can realize the high-value utilization of H2S.

[0006] To achieve the above object, the present invention adopts the following technical solutions: An atomically dispersed Cu metal catalytic material supported on BCN, using urea as the nitrogen source, boric acid as the boron source, barbituric acid and urea as the carbon source, and a copper complex as the metal source. After heating, stirring, drying, grinding, calcining and other treatments, a mutually interpenetrating two-dimensional nanosheet structure is obtained, wherein the Cu loading is 0.5 wt%-2.0 wt%.

[0007] The preparation method of the atomically dispersed Cu metal catalytic material supported on BCN includes the following steps: a. Take a copper salt and a complexing agent phthalocyanine and dissolve them in distilled water. Heat, stir and evaporate to dryness, and obtain a metal copper complex powder after drying and grinding. b. Take the nitrogen source, boron source, carbon source and the copper complex powder obtained in step a, dissolve them in distilled water, heat and stir until evaporated to dryness, and grind to a powder after drying. c. Transfer the powder sample obtained in step b to a tubular furnace. After calcination and washing, a flaky carbon-doped boron nitride material, i.e., a multifunctional copper-based composite catalyst, is obtained.

[0008] Further, in step a, the heating temperature is 60 °C, the stirring speed is 600 r·min -1 , and the stirring time is 12 h; the copper salt is copper nitrate hexahydrate, and the molar ratio of the copper salt to phthalocyanine is 1:2.

[0009] Further, in step b, the molar ratio of the nitrogen source, boron source, carbon source, and copper complex is 10:0.9:0.1:0.5. The nitrogen source is any one of urea, dicyandiamide, and melamine. The boron source is boric acid, the carbon source is barbituric acid, the heating and stirring temperature is 80 °C, and the stirring speed is 600 r·min -1 .

[0010] Further, in steps a and b, the drying temperature is 70 °C and the time is 24 h.

[0011] Further, in step c, the calcination is carried out in high-purity nitrogen with a heating rate of 2 °C / min and calcined at a calcination temperature of 700 °C to 900 °C for 2 h.

[0012] The above-obtained BCN-supported atomically dispersed Cu metal catalytic material can be used to catalyze the preparation of thiobenzamide by the nucleophilic addition of H2S to aryl nitrile compounds after being alternately washed with 5% hydrochloric acid and deionized water.

[0013] The specific conditions for the nucleophilic addition of H2S to benzonitrile to prepare thiobenzamide are as follows: reaction substrate: 102 μL of benzonitrile; catalyst dosage is 40 mg, and the co-agent is 0.2 mL of isopropylamine; the raw gas components and contents are in turn: 5% H2S, with N2 as the balance gas; the raw gas flow rate is 30 mL / min; the reaction temperature is 50 °C to 80 °C, preferably 70 °C.

[0014] The preparation of aniline by the reduction of nitrobenzene with H2S: reaction substrate: 102 μL of nitrobenzene; catalyst dosage is 40 mg, and the co-agent is 0.2 mL of isopropylamine; the raw gas components and contents are in turn: 5% H2S, with N2 as the balance gas; the raw gas flow rate is 30 mL / min; the reaction temperature is 80 °C to 110 °C, preferably 100 °C.

[0015] The present invention has the following advantages and beneficial effects: 1. The BCN-supported atomically dispersed Cu metal catalytic material prepared by the present invention is a material with an interpenetrating two-dimensional nanosheet structure prepared by regulating the ratio of B, C, and N reasonably and designing the calcination temperature program of the material. It has a large specific surface area, can expose more active sites, and is beneficial to improving the mass transfer and heat transfer effects.

[0016] 2. In the process of preparing the BCN-supported atomically dispersed Cu metal catalytic material of the present invention, through high-temperature pyrolysis, copper element atoms are uniformly dispersed in the BCN material at the atomic level, thereby improving the dispersibility and stability of metal active sites, and making it have the characteristics of high activity and selectivity. Its raw materials are cheap, the preparation process is simple, the metal dispersion of the obtained catalyst is good, it is not easy to agglomerate, it is easy to realize industrial production, and it has a wide application prospect.

[0017] 3. The BCN-supported atomically dispersed Cu metal obtained by the present invention has an appropriate adsorption and activation ability for H2S, can prevent the active sites from being poisoned, and thus can improve the reaction efficiency of nucleophilic addition of H2S to benzonitrile to prepare thiobenzamide and reduction of nitrobenzene by H2S to prepare aniline.

[0018] 4. By introducing Cu metal elements, the present invention innovatively synthesizes a Cu / BCN catalyst. Compared with a single M-N coordination structure, the Cu / BCN catalyst forms a co-coordination structure of Cu and N. It not only retains the high stability of the BCN material, but also has more excellent catalytic performance, which makes it not only show high catalytic activity and product selectivity in the reaction of catalytic reduction of aryl nitrile compounds by H2S to thiobenzamide, but also has stronger anti-sulfur poisoning ability.

[0019] 5. The Cu-based catalyst prepared by the present invention can realize the high-value utilization of H2S in waste gas. Compared with Cu / BCN catalysts with different calcination temperatures and different N sources, it has better catalytic performance, is not easy to deactivate due to sulfur poisoning, has a wide substrate applicability, and has a great industrial application prospect. Description of the Drawings

[0020] Figure 1 X-ray powder diffraction spectra of Cu / BCN prepared in Examples 1-5.

[0021] Figure 2 Fourier transform infrared spectra of Cu / BCN prepared in Examples 1-5.

[0022] Figure 3 Catalytic activity comparison diagrams of Cu / BCN prepared in Examples 1-3 and Comparative Examples 1-2 in the catalytic reduction of nitrobenzene by H2S to prepare aniline.

[0023] Figure 4Catalytic activity comparison diagram of Cu / BCN prepared in Example 2, Example 4, Example 5 and Comparative Examples 1-2 for the nucleophilic addition of H2S to benzonitrile to produce thiobenzamide.

[0024] Figure 5 Catalytic activity comparison diagram of atomically dispersed Cu metal catalytic materials supported on BCN with different raw material ratios prepared in Examples 6-9 for the nucleophilic addition of H2S to benzonitrile to produce thiobenzamide at 70 °C. Figure 6 SEM images of Cu / BCN prepared in Example 2 (a) and Example 7 (b).

[0025] Figure 7 N2-sorption curve diagrams of Cu / BCN prepared in Examples 1-7.

[0026] Figure 8 Pore size distribution diagrams of Cu / BCN prepared in Examples 1-7.

[0027] Figure 9 XPS diagrams of Cu / BCN prepared in Example 2; where (a) Cu 2p; (b) B 1s; (c) C 1s; (d) N 1s.

[0028] Figure 10 Synchrotron radiation XAS spectrum diagram of atomically dispersed Cu metal catalytic material supported on BCN prepared in Example 2. Detailed implementation manners

[0029] In order to make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific implementation manners, but the present invention is not limited thereto.

[0030] Example 1 An atomically dispersed Cu metal catalytic material supported on BCN, the preparation of which includes the following steps: a. Under the conditions of water bath heating at 60 °C and magnetic stirring at 600 r·min - 1 In 60 mL of deionized water, phthalocyanine and Cu(NO3)2·6H2O are added, and the molar ratio of Cu(NO3)2·6H2O to phthalocyanine is 1:2. After observing stirring and evaporation to dryness, the obtained solid is collected and dried in an oven at 80 °C for 12 h and then ground to obtain copper complex C 32 H 16 CuN8; b. Add urea, boric acid, barbituric acid and copper complex into 120 mL of deionized water. The molar ratio of urea, boric acid, barbituric acid and copper complex is 10:0.9:0.1:0.5. The amount of copper complex added is 0.302 g. Under the conditions of heating and stirring in a water bath at 70 °C and 600 r·min - 1 After complete dissolution and evaporation to dryness, collect the obtained solid and dry it at 70 °C, and then grind it thoroughly to a powder; c. Transfer the powder dried in step b into a tubular furnace. In high-purity nitrogen, heat it to 700 °C at a rate of 2 °C / min and calcine for 2 h. Then alternately centrifuge and wash with 5% hydrochloric acid solution and deionized water until the supernatant is colorless, clear and transparent to remove the surface copper ions. Then dry it in an oven at 80 °C for 12 h. According to ICP test, the copper loading in the catalyst is 0.96%.

[0031] Example 2 A BCN-supported atomically dispersed Cu metal catalytic material, and its preparation includes the following steps: a. Under the condition of heating in a water bath at 60 °C and magnetic stirring at 600 r·min - 1 Add phthalocyanine and Cu(NO3)2·6H2O into 60 mL of deionized water. The molar ratio of Cu(NO3)2·6H2O to phthalocyanine is 1:2. Observe the stirring and evaporation to dryness. Collect the obtained solid and dry it in an oven at 70 °C for 12 h, and then grind it finely to obtain copper complex C 32 H 16 CuN8; b. Add urea, boric acid, barbituric acid and copper complex into 120 mL of deionized water. The molar ratio of urea, boric acid, barbituric acid and copper complex is 10:0.9:0.1:0.5. The amount of copper complex added is 0.302 g. Under the conditions of heating and stirring in a water bath at 70 °C and 600 r·min - 1 After complete dissolution and evaporation to dryness, collect the obtained solid and dry it at 70 °C, and then grind it thoroughly to a powder; c. Transfer the powder dried in step b into a tubular furnace. In high-purity nitrogen, heat it to 800 °C at a rate of 2 °C / min and calcine for 2 h. Then alternately centrifuge and wash with 5% hydrochloric acid solution and deionized water until the supernatant is colorless, clear and transparent to remove the surface copper ions. Then dry it in an oven at 80 °C for 12 h. According to ICP test, the copper loading in the catalyst is 0.72% Example 3 A BCN-supported atomically dispersed Cu metal catalytic material, and its preparation includes the following steps: a. Under the condition of heating in a water bath at 60 °C and 600 r·min- 1 Under the condition of magnetic stirring, phthalocyanine and Cu(NO3)2·6H2O were added to 60 mL of deionized water, where the molar ratio of Cu(NO3)2·6H2O to phthalocyanine was 1:2. It was observed that the mixture was stirred and evaporated to dryness. The obtained solid was collected and dried in an oven at 70 °C for 12 h, and then ground to obtain copper complex C 32 H 16 CuN8; b. Urea, boric acid, barbituric acid and copper complex were added to 120 mL of deionized water. The molar ratio of urea, boric acid, barbituric acid and copper complex was 10:0.9:0.1:0.5, and the amount of copper complex added was 0.302 g. Under the conditions of heating and stirring in a water bath at 70 °C and 600 r·min - 1 After heating and stirring, after it was completely dissolved and evaporated to dryness, the obtained solid was collected and dried at 70 °C, and then thoroughly ground into a powder after drying; c. The powder dried in step b was transferred into a tubular furnace. In high-purity nitrogen, it was heated to 900 °C at a rate of 2 °C / min and calcined for 2 h. Then, it was alternately centrifuged and washed with 5% hydrochloric acid solution and deionized water until the supernatant was colorless, clear and transparent to remove the surface copper ions. Then, it was dried in an oven at 80 °C for 12 h. According to the ICP test, the copper loading in the catalyst was 0.86%.

[0032] Example 4 A BCN-supported atomically dispersed Cu metal catalytic material, and its preparation includes the following steps: a. Under the condition of heating and stirring in a water bath at 60 °C and 600 r·min - 1 Under the condition of magnetic stirring, phthalocyanine and Cu(NO3)2·6H2O were added to 60 mL of deionized water, where the molar ratio of Cu(NO3)2·6H2O to phthalocyanine was 1:2. It was observed that the mixture was stirred and evaporated to dryness. The obtained solid was collected and dried in an oven at 70 °C for 12 h, and then ground to obtain copper complex C 32 H 16 CuN8; b. Dicyandiamide, boric acid, barbituric acid and copper complex were added to 120 mL of deionized water. The molar ratio of dicyandiamide, boric acid, barbituric acid and copper complex was 10:0.9:0.1:0.5, and the amount of copper complex added was 0.302 g. Under the conditions of heating and stirring in a water bath at 70 °C and 600 r·min -1 After heating and stirring, after it was completely dissolved and evaporated to dryness, the obtained solid was collected and dried at 70 °C, and then thoroughly ground into a powder after drying; c. Transfer the powder dried in step b into a tubular furnace. Under high-purity nitrogen, heat it to 800 °C at a rate of 2 °C / min and calcine for 2 h. Then, alternately centrifuge and wash it with 5% hydrochloric acid solution and deionized water until the supernatant is colorless, clear, and transparent to remove the surface copper ions. After that, dry it in an oven at 80 °C for 12 h. According to ICP test, the copper loading in the catalyst is 1.24%.

[0033] Example 5 A BCN-supported atomically dispersed Cu metal catalytic material, and its preparation includes the following steps: a. Under the conditions of 60 °C water bath heating and magnetic stirring at 600 r·min -1 add phthalocyanine and Cu(NO3)2·6H2O into 60 mL of deionized water. The molar ratio of Cu(NO3)2·6H2O to phthalocyanine is 1:2. Observe the stirring and evaporation to dryness, collect the obtained solid, dry it in an oven at 70 °C for 12 h, and then grind it finely to obtain copper complex C 32 H 16 CuN8; b. Add melamine, boric acid, barbituric acid, and copper complex into 120 mL of deionized water. The molar ratio of melamine, boric acid, barbituric acid, and copper complex is 10:0.9:0.1:0.5, and the addition amount of the copper complex is 0.302 g. Under the conditions of 70 °C water bath heating and heating and stirring at 600 r·min - 1 after it is completely dissolved and evaporated to dryness, collect the obtained solid and dry it at 70 °C, and then grind it sufficiently to a powder; c. Transfer the powder dried in step b into a tubular furnace. Under high-purity nitrogen, heat it to 800 °C at a rate of 2 °C / min and calcine for 2 h. Then, alternately centrifuge and wash it with 5% hydrochloric acid solution and deionized water until the supernatant is colorless, clear, and transparent to remove the surface copper ions. After that, dry it in an oven at 80 °C for 12 h. According to ICP test, the copper loading in the catalyst is 1.5%.

[0034] Example 6 A BCN-supported atomically dispersed Cu metal catalytic material, and its preparation includes the following steps: a. Under the conditions of 60 °C water bath heating and magnetic stirring at 600 r·min - 1 add phthalocyanine and Cu(NO3)2·6H2O into 60 mL of deionized water. The molar ratio of Cu(NO3)2·6H2O to phthalocyanine is 1:2. Observe the stirring and evaporation to dryness, collect the obtained solid, dry it in an oven at 70 °C for 12 h, and then grind it finely to obtain copper complex C 32 H 16 CuN8; b. Add urea, boric acid, barbituric acid and copper complex into 120 mL of deionized water. The molar ratio of urea, boric acid and barbituric acid is 10:0.9:0.15, and the addition amount of the copper complex is 0.302 g. Under the conditions of heating and stirring in a water bath at 70 °C and 600 r·min - 1 After it is completely dissolved and evaporated to dryness, collect the obtained solid and dry it at 70 °C, and then grind it thoroughly to a powder state after drying; c. Transfer the powder after drying in step b into a tubular furnace. In high-purity nitrogen, heat it to 800 °C at a rate of 2 °C / min and calcine for 2 h. Then, alternately centrifuge and wash it with 5% hydrochloric acid solution and deionized water until the supernatant is colorless, clear and transparent to remove the surface copper ions. Then dry it in an oven at 80 °C for 12 h. According to ICP test, the copper loading in the catalyst is 1.68%.

[0035] Example 7 A BCN-supported atomically dispersed Cu metal catalytic material, and its preparation includes the following steps: a. Under the magnetic stirring conditions of heating in a water bath at 60 °C and 600 r·min - 1 Add phthalocyanine and Cu(NO3)2·6H2O into 60 mL of deionized water. The molar ratio of Cu(NO3)2·6H2O to phthalocyanine is 1:2. Observe that it is stirred and evaporated to dryness. Collect the obtained solid and dry it in an oven at 80 °C for 12 h, and then grind it finely to obtain copper complex C 32 H 16 CuN8; b. Add urea, boric acid, barbituric acid and copper complex into 120 mL of deionized water. The molar ratio of urea, boric acid, barbituric acid and copper complex is 10:0.9:0.2:0.5, and the addition amount of the copper complex is 0.302 g. Under the conditions of heating and stirring in a water bath at 70 °C and 600 r·min - 1 After it is completely dissolved and evaporated to dryness, collect the obtained solid and dry it at 70 °C, and then grind it thoroughly to a powder state after drying.

[0036] c. Transfer the powder after drying in step b into a tubular furnace. In high-purity nitrogen, heat it to 800 °C at a rate of 2 °C / min and calcine for 2 h. Then, alternately centrifuge and wash it with 5% hydrochloric acid solution and deionized water until the supernatant is colorless, clear and transparent to remove the surface copper ions. Then dry it in an oven at 80 °C for 12 h. According to ICP test, the copper loading in the catalyst is 1.58%.

[0037] Example 8 A BCN-supported atomically dispersed Cu metal catalytic material, and its preparation includes the following steps: a. Under the conditions of heating in a water bath at 60 °C and magnetic stirring at 600 r·min - 1 In 60 mL of deionized water, phthalocyanine and Cu(NO3)2·6H2O were added under magnetic stirring. The molar ratio of Cu(NO3)2·6H2O to phthalocyanine was 1:2. After observing that the mixture was stirred and evaporated to dryness, the obtained solid was collected and dried in an oven at 70 °C for 12 h, and then ground to obtain copper complex C 32 H 16 CuN8: b. Urea, boric acid, barbituric acid and copper complex were added to 120 mL of deionized water. The molar ratio of urea, boric acid, barbituric acid to copper complex was 10:0.9:0.25:0.5, and the amount of copper complex added was 0.302 g. Under the conditions of heating and stirring in a water bath at 70 °C and 600 r·min - 1 After complete dissolution and evaporation to dryness, the obtained solid was collected and dried at 70 °C, and then thoroughly ground to a powder after drying.

[0038] c. The powder dried in step b was transferred into a tube furnace. In high-purity nitrogen, it was heated to 800 °C at a rate of 2 °C / min and calcined for 2 h. Then it was alternately centrifuged and washed with 5% hydrochloric acid solution and deionized water until the supernatant was colorless, clear and transparent to remove surface copper ions. After that, it was dried in an oven at 80 °C for 12 h. According to ICP test, the copper loading in the catalyst was 1.67%.

[0039] Example 9 A BCN-supported atomically dispersed Cu metal catalytic material, the preparation of which includes the following steps: a. Under the conditions of heating in a water bath at 60 °C and magnetic stirring at 600 r·min - 1 In 60 mL of deionized water, phthalocyanine and Cu(NO3)2·6H2O were added under magnetic stirring. The molar ratio of Cu(NO3)2·6H2O to phthalocyanine was 1:2. After observing that the mixture was stirred and evaporated to dryness, the obtained solid was collected and dried in an oven at 70 °C for 12 h, and then ground to obtain copper complex C 32 H 16 CuN8: b. Urea, boric acid, barbituric acid and copper complex were added to 120 mL of deionized water. The molar ratio of urea, boric acid, barbituric acid to copper complex was 10:0.9:0.3:0.5, and the amount of copper complex added was 0.302 g. Under the conditions of heating and stirring in a water bath at 70 °C and 600 r·min - 1 After complete dissolution and evaporation to dryness, the obtained solid was collected and dried at 70 °C, and then thoroughly ground to a powder after drying.

[0040] c. Transfer the powder dried in step b into a tubular furnace. In high-purity nitrogen, heat it at a rate of 2 °C / min to 800 °C, calcine for 2 h, and then alternately centrifuge and wash with 5% hydrochloric acid solution and deionized water until the supernatant is colorless, clear and transparent to remove the surface copper ions. Then dry it in an oven at 80 °C for 12 h. According to ICP test, the copper loading in the catalyst is 1.50%.

[0041] Comparative Example 1 A BCN catalytic material, the preparation of which includes the following steps: a. Add urea, boric acid, and barbituric acid to 120 mL of deionized water. The molar ratio of urea, boric acid, and barbituric acid is 10:0.9:0.1. Under the conditions of heating and stirring in a 70 °C water bath and 600 r·min - 1 heat stirring, wait for it to completely dissolve and evaporate to dryness, then collect the obtained solid and dry it at 70 °C, and fully grind it into powder after drying; b. Transfer the powder dried in step a into a tubular furnace. In high-purity nitrogen, heat it at a rate of 2 °C / min to 800 °C, calcine for 2 h until the supernatant is colorless, clear and transparent.

[0042] Comparative Example 2 The catalyst used in Comparative Example 2 is commercial nano-copper oxide.

[0043] The examples and comparative examples were measured by an X-ray powder diffractometer and a field emission scanning electron microscope.

[0044] X-ray powder diffractometer (XRD): The XRD test instrument for the sample is the X'Pert PRO type X-ray powder diffractometer of Panalytical Company in the Netherlands. The X-ray powder diffractometer selects Cu target K α light source, the operating voltage is 45 kV, and the current is 40 mA.

[0045] Field emission scanning electron microscope (SEM): The SEM image of the sample was observed on an S-4800 type scanning electron microscope. The test current and voltage are 7 μA and 5 kV respectively.

[0046] Figure 1 XRD patterns of the BCN-supported atomically dispersed Cu metal catalytic materials prepared for Examples 1-5. As Figure 1 shown, characteristic diffraction peaks belonging to the (002) and (004) planes of graphite carbon appeared at 26° and 43°, indicating that the Cu doping did not affect the basic structure of BCN. In addition, no diffraction peaks belonging to Cu metal and its related oxides were detected, indicating that there was no agglomeration of metals and their oxides.

[0047] Figure 2 FT-IR spectra of the BCN-supported atomically dispersed Cu metal catalysts prepared in Examples 1-5. As can be seen from the figure, at 3223 cm -1 , 1628 cm -1 , 1372 cm -1 , 1055 cm -1 and 788 cm -1 appear O-H bond, sp 2 C=N stretching vibration, B-N in-plane stretching vibration, B-C vibration and B-N-B out-of-plane bending vibration respectively, indicating the formation of an amorphous BCN structure.

[0048] Reaction test for the production of aniline by the reduction of nitrobenzene with H2S: After the BCN-supported atomically dispersed Cu metal catalysts prepared in Examples 1-3 were simply ground, they were used to evaluate the reaction activity for the production of aniline. The test conditions were as follows: 102 μL of nitrobenzene, the catalyst loading was 0.04 g, the feed gas consisted of 5% H2S and balance gas nitrogen, the promoter was 0.2 mL of isopropylamine, the feed gas flow rate was 30 mL / min, and the reaction temperature was 80 - 110 °C. The reaction products were quantitatively analyzed by gas chromatography. The initial concentration of nitrobenzene was represented by C 0(硝基苯) , and the concentration of nitrobenzene after the reaction measured by gas chromatography was represented by C 1(硝基苯) . The calculation formula for the conversion rate of nitrobenzene (Conversion) was as follows: ; The concentration of aniline after the reaction measured by gas chromatography was represented by C 1(苯胺) . The calculation formula for selectivity (Selectivity) was as follows: .

[0049] Figure 3 Graph showing the comparison of the catalytic activities of the BCN-supported atomically dispersed Cu metal catalysts prepared in Examples 1-3 and Comparative Examples 1-2 for the reduction of nitrobenzene with H2S to produce aniline at 100 °C. As can be seen from the figure and Table 1, the conversion rate and selectivity of the catalytic material of Example 2 reached 94% and 98% respectively at 100 °C, which were significantly better than those of other examples, indicating its good catalytic activity and selectivity.

[0050] Table 1 Activity statistics of the materials prepared in Examples and Comparative Examples for the reduction of nitrobenzene with H2S to produce aniline Reaction test for the production of thiobenzamide by the nucleophilic addition of H2S to benzonitrile: After simple grinding, the BCN-supported atomically dispersed Cu metal catalysts prepared in Example 2, Example 4, and Example 5 were used for the evaluation of the reaction activity for preparing thiobenzamide. The test conditions were as follows: 102 μ of benzonitrile, the catalyst loading was 0.04 g, the raw material gas consisted of 5% H2S and the balance nitrogen gas, the promoter was 0.2 mL of isopropylamine, the raw material gas flow rate was 30 mL / min, and the reaction temperature was 50 - 80 °C. The reaction products were quantitatively analyzed by gas chromatography. The initial concentration of benzonitrile was represented by C 0(苯甲腈) and the concentration of benzonitrile after the reaction measured by gas chromatography was represented by C 1(苯甲腈) . The calculation formula for the conversion of benzonitrile was as follows: ; The concentration of thiobenzamide after the reaction measured by gas chromatography was represented by C 1(硫代苯甲酰胺) . The calculation formula for selectivity was as follows: .

[0051] The calculation methods for the conversion and selectivity of benzonitrile with different substituents to prepare thiobenzamides with different substituents were similar to the above.

[0052] Figure 4 Figure for the comparison of the catalytic activities of the BCN-supported atomically dispersed Cu metal catalysts prepared in Examples 2, 4, and 5 for the nucleophilic addition of H2S to benzonitrile to prepare thiobenzamide at 70 °C. As can be seen from the figure and Table 2, the conversion and selectivity of the catalyst in Example 2 reached 93.7% and 99.8% respectively at 70 °C, which were significantly better than those of other examples, indicating its good catalytic activity and selectivity.

[0053] Table 2 Statistical table of the activities of the materials prepared in Examples and Comparative Examples for the nucleophilic addition of H2S to benzonitrile to prepare thiobenzamide Figure 5 Figure for the comparison of the catalytic activities of the BCN-supported atomically dispersed Cu metal catalysts with different raw material ratios prepared in Examples 2, 6 - 9 for the nucleophilic addition of H2S to benzonitrile to prepare thiobenzamide at 70 °C. As can be seen from the figure and Table 3, the conversion and selectivity of the catalyst in Example 2 reached 93.7% and 99.8% respectively at 70 °C, which were significantly better than those of other examples, indicating its good catalytic activity and selectivity.

[0054] Table 3 Statistical table of the activities of the materials prepared in Examples with different raw material ratios for the nucleophilic addition of H2S to benzonitrile to prepare thiobenzamide Figure 6 SEM images of the BCN-supported atomically dispersed Cu metal catalytic materials prepared for Example 2 (6a) and Example 7 (6b). As Figure 6 shown in (a), an interpenetrating two-dimensional carbon nanosheet structure is presented, while the interpenetrating two-dimensional carbon nanosheet structure cannot be obtained at the ratio of Example 7. Therefore, its conversion rate of benzonitrile and selectivity of thiobenzamide are lower than those of Example 2, but still better than those of the comparative example.

[0055] Figure 7 N2-sorption curves of the BCN-supported atomically dispersed Cu metal catalytic materials prepared for Examples 1-7. The results show that the samples are type isotherm curves and have an H3-type hysteresis loop, proving that Cu / BCN-800 has a mesoporous structure with a specific surface area of 724.0 m 2 ·g -1 .

[0056] Figure 8 Pore size distribution diagrams of the BCN-supported atomic Cu metal catalytic materials prepared for Examples 1-7. As Figure 8 shown, the BJH pore size distribution of Example 2 is in the range of 3.5 - 6.6 nm.

[0057] Figure 9 XPS spectra of the BCN-supported atomically dispersed Cu metal catalytic materials prepared for Example 2. According to ICP tests, the copper content of the catalyst prepared in Example 2 is 0.7%. As Figure 9 shown in (a), the Cu 2p spectrum shows two peaks at 932.4 eV and 952.2 eV, corresponding to Cu 0 , and at 934.8 eV and 954.7 eV corresponding to Cu + , which is also confirmed by the satellite peak at 943.7 eV. The B 1s spectrum in (b) shows two peaks at 190.7 eV and 191.8 eV, which are characteristic of B−N−C and B−O bonds. The peak at 284.8 eV in the C 1s spectrum of (c) is related to sp 2 C-C and C-O bonds, while the peaks at 285.9 eV and 288.4 eV are related to C-N and C-O bonds. The N 1s spectrum in (d) fits two peaks at 398.5 eV and 399.8 eV, which are attributed to C-N and Cu-N respectively. Combining the above, it shows that the Cu element is mainly anchored on the BCN material in the form of coordination with N, which is consistent with the design goal.

[0058] Figure 10XAS spectrum of the BCN-supported atomically dispersed Cu metal catalyst prepared in Example 2. It can be found from the XANES spectrum in Figure a that the Cu absorption edge of Example 2 is close to that of Cu2O, indicating that the valence state of Cu mainly exists in the form of +1. It can be found from the EXAFS spectrum in Figure b that there is no signal peak attributed to the Cu-Cu bond at 2.2 Å and 4.1 Å in Example 2, while there is an obvious signal peak attributed to the Cu-N bond at 1.5 Å, indicating that Cu exists in the form of Cu-N coordination and there is no phenomenon of Cu atom aggregation.

[0059] In summary, the BCN-supported atomically dispersed Cu metal catalysts prepared at different calcination temperatures have different catalytic performances in the catalytic reaction of the nucleophilic addition of H2S to benzonitrile to produce thiobenzamide. Among them, Cu / BCN-800 has the highest catalytic activity. It has an interpenetrating nanosheet morphology, a large specific surface area, and contains a small amount of metallic Cu, which can effectively catalyze the reaction of the nucleophilic addition of H2S to benzonitrile to produce thiobenzamide, and has great application potential.

[0060] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A preparation method of a multifunctional copper-based composite catalyst, characterized in that: It includes the following steps: a. Dissolve copper salt and the complexing agent phthalocyanine in distilled water, heat and stir until evaporated to dryness, and obtain metal copper complex powder after drying and grinding; b. Take the nitrogen source, boron source, carbon source and the copper complex powder obtained in step a, dissolve them in distilled water, heat and stir until evaporated to dryness, and grind to powder after drying; c. Transfer the powder sample obtained in step b to a tubular furnace, and obtain a flaky carbon-doped boron nitride material, namely a multifunctional copper-based composite catalyst, after calcination and washing.

2. The preparation method of the multifunctional copper-based composite catalytic material according to claim 1, wherein: The temperature of heating in step a is 60 °C, the rotation speed of stirring is 600 r·min -1 , the stirring time is 12 h; the copper salt is copper nitrate hexahydrate, and the molar ratio of the copper salt to phthalocyanine is 1:

2.

3. The preparation method of the multifunctional copper-based composite catalytic material according to claim 1, characterized in that: In step b, the molar ratio of the nitrogen source, boron source, carbon source and copper complex is 10:0.9:0.1:0.

5. The nitrogen source is any one of urea, dicyandiamide, and melamine. The boron source is boric acid. The carbon source is barbituric acid. The temperature for heating and stirring is 70 °C.

4. The preparation method of the multifunctional copper-based composite catalytic material according to claim 1, characterized in that: In steps a and b, the drying temperature is 70 °C and the time is 24 h.

5. The preparation method of the multifunctional copper-based composite catalytic material according to claim 1, characterized in that: In step c, the calcination is carried out in high-purity nitrogen, heating at a rate of 2 °C / min to 700 °C - 900 °C, and the calcination time is 2 h.

6. The preparation method of the multifunctional copper-based composite catalytic material according to claim 1, wherein: The obtained multifunctional copper-based composite catalytic material has an interpenetrating two-dimensional nanosheet structure.

7. A multifunctional copper-based composite catalytic material prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The Cu loading is 0.5 wt% - 2.0 wt%.

8. Application of the multifunctional copper-based composite catalytic material as described in claim 7 in catalyzing the nucleophilic addition of H2S to aryl nitrile compounds to prepare thiobenzamide and reducing nitroarenes to prepare aminoarenes.

9. The application according to claim 8, wherein: The conditions are normal pressure reaction for 2 h. The reaction temperature for preparing aminoarenes from nitroarenes is 100 °C, and the reaction temperature for preparing thiobenzamide from aryl nitrile compounds is 70 °C.

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