A Cu-M two-component single-atom catalyst and its preparation method and application

Abstract

The present invention discloses a Cu-M two-component single-atom catalyst and its preparation method and application. The preparation method of the Cu-M two-component single-atom catalyst comprises: 1) dissolving zinc salt, copper salt, non-precious metal M salt and imidazole compound in solvent A respectively; 2) obtaining ZIF-8 powder; 3) mixing copper salt solution, non-precious metal M salt solution and ZIF-8 powder, placing in a supergravity reactor for stirring reaction, and obtaining Cu-M@ZIF-8; 4) the Cu-M@ZIF-8 sample is treated with acid to obtain Cu-M@ZIF-8 containing defects; 5) the Cu-M@ZIF-8 sample containing defects is calcined in an inert atmosphere using a Joule heater to obtain a Cu-M two-component single-atom catalyst. The present invention provides the application of the catalyst in the selective hydrogenation of acetylene to ethylene reaction, with the advantages of high acetylene conversion, high ethylene selectivity and good stability.

Description

Technical Field

[0001] The invention relates to a Cu-M two-component single-atom catalyst and a preparation method thereof and application thereof in acetylene selective hydrogenation reaction. Background Art

[0002] Selective hydrogenation of hydrocarbons is a fundamental reaction in the petrochemical industry, with a key example being the selective conversion of trace acetylene impurities in ethylene streams to ethylene while preventing over-hydrogenation of ethylene to unwanted ethane. Despite great progress in Pd-based catalysts, it remains challenging to optimize these parameters simultaneously, especially in the presence of excess H2 and C2H4 in the front-end process. In addition, Pd-based catalysts suffer from poor selectivity and high cost. In search of environmentally friendly and cost-effective solutions, various strategies have been explored, including reducing the amount of precious metals through a "site isolation" approach and developing non-precious metal / metal oxide catalysts. In response, there is a strong desire to use affordable, non-toxic, and abundant transition metals (such as Co or Ni) to make catalysts that can achieve catalytic performance matching that of Pd-based catalysts. A large number of studies have focused on non-precious metal oxides (including CeO2) to develop low-cost, high-performance catalysts for the hydrogenation of alkynes. However, these oxide catalysts generally require relatively high operating temperatures due to their limited H2 activation ability. Notably, researchers have explored non-precious metals that are abundant on Earth, especially copper-based catalysts. Compared with other non-noble metals, Cu has great potential for the selective hydrogenation of acetylene.

[0003] In the previous paper [Yuxue Yue, etc. Tailoring Cu-Zn Dual-Atom Sites with Reordering d-Orbital Splitting Manner for Highly Efficient Acetylene Semihydrogenation. ACS Catal. 2024, 14, 3900-3911], our research group disclosed a catalyst with Cu-Zn diatomic sites and used it in the selective hydrogenation of acetylene to ethylene. The results show that nitrogen-doped Cu-Zn diatomic cooperative sites (denoted as Cu-Zn diatomic sites) were identified as the main active centers, and these sites have good catalytic activity and selectivity for the selective hydrogenation of acetylene. A gas mixture containing 0.33% acetylene, 0.66% H2 and 33% ethylene was heated at 35 mL·min -1 The flow rate is fed into the reactor, and the corresponding space velocity is 6000 mL·h -1 ·g -1At 180℃, among the CuZn / NC1, CuZn / NC2 and CuZn / NC3 catalysts with Cu / Zn molar ratios of 0.47, 0.77 and 1.64 respectively, the CuZn / NC2 catalyst with the largest number of Cu-Zn diatomic sites has an acetylene conversion of 97% and an ethylene selectivity of 97.5%, while the conversions of CuZn / NC1 and CuZn / NC3 are 92.9 and 96.7% and the selectivities are 94.8 and 90.2% respectively. However, when the reaction temperature is reduced, the acetylene conversion of the three catalysts decreases significantly.

[0004] Based on the above background, it is necessary to develop improved catalytic materials and design a catalyst with high acetylene conversion rate and high ethylene selectivity at a lower reaction temperature, so as to facilitate the industrial production of ethylene. Summary of the invention

[0005] The object of the present invention is to provide a two-component single-atom catalyst (Cu-M two-component single-atom catalyst) and a preparation method thereof and application in the selective hydrogenation reaction of acetylene. The catalyst prepared by the present invention has the advantages of high acetylene conversion rate, high ethylene selectivity and good catalyst stability in the selective hydrogenation reaction of acetylene at a relatively low reaction temperature.

[0006] The technical solution adopted by the present invention is described in detail below.

[0007] In a first aspect, the present invention provides a method for preparing a Cu-M two-component single-atom catalyst, wherein the M non-precious metal is selected from at least one of zinc, nickel, and chromium, and the preparation method comprises the following steps:

[0008] 1) Dissolve zinc salt, copper salt, non-noble metal M salt and imidazole compound in solvent A respectively according to a certain proportion;

[0009] 2) slowly adding the imidazole compound solution obtained in step 1) into the Zn salt solution, placing the mixed solution in a supergravity reactor for reaction, wherein the imidazole and the non-precious metal M salt self-assemble into a ZIF-8 structure in the solvent A, filtering, washing, drying, and grinding to obtain a ZIF-8 powder with uniform particle size;

[0010] 3) Mixing the copper salt solution and the non-precious metal M salt solution obtained in step 1) with the ZIF-8 powder obtained in step 2), and placing them in a supergravity reactor again for stirring reaction, wherein the Cu salt and the non-precious metal M salt and imidazole are assembled on the surface of ZIF-8 and cover ZIF-8, and then separated, washed and dried to obtain Cu-M@ZIF-8; the feeding ratio of the copper salt solution and the non-precious metal M salt solution is based on the element molar ratio of copper:M=1:1-1:2, and the feeding ratio of the copper salt solution to the ZIF-8 powder is 1mmol:3-5g in terms of the ratio of the molar number of the copper element to the mass of the ZIF-8 powder;

[0011] 4) The Cu-M@ZIF-8 sample obtained in step 3) is treated with acid, washed to neutrality, and dried to obtain Cu-M@ZIF-8 containing defects;

[0012] 5) The defective Cu-M@ZIF-8 sample obtained in step 4) is calcined in an inert atmosphere using a Joule heater to obtain a Cu-M two-component single-atom catalyst.

[0013] Furthermore, the non-precious metal M salt described in step 1) is selected from one or more of acetate, nitrate and chloride.

[0014] Furthermore, the imidazole compound in step 1) is selected from one or more of 4-methylimidazole, 3-methylimidazole, and 2-methylimidazole.

[0015] Furthermore, the solvent A in step 1) is selected from deionized water, methanol, ethanol or acetone.

[0016] Furthermore, the reaction conditions in the high gravity reactor in step 2) are: temperature of 25-70° C., rotation speed of 100-600 rpm, and time of 6 to 24 h.

[0017] Furthermore, the washing solvent in step 2) is selected from at least one of deionized water, methanol, ethanol, and acetonitrile, and the washing is performed 2 to 3 times.

[0018] Furthermore, the drying conditions in step 2) are vacuum drying at a temperature of 40-80° C. for 6 to 12 hours.

[0019] Furthermore, the grinding in step 2) is performed by ball milling, the ball milling speed is 100-300 rpm, and the time is 0.5-3 h.

[0020] Furthermore, the reaction conditions of the high gravity reactor described in step 3) are: temperature of 25-70°C, rotation speed of 100-600rpm, and time of 6 to 24h.

[0021] Furthermore, the separation in step 3) is performed by centrifugation, with a centrifugal speed of 10000-15000 rpm and a time of more than 5 minutes.

[0022] Furthermore, the detergent in step 3) is one or two of DMF, ethanol, deionized water, acetonitrile and methanol, and the washing is performed 2 to 4 times.

[0023] Furthermore, the drying conditions in step 3) are vacuum drying at a temperature of 60° C. for a time of 6 to 12 hours.

[0024] Furthermore, the acid in step 4) is selected from one of sulfuric acid, hydrochloric acid and nitric acid, the acid concentration is 0.3-0.5M, and the pickling is performed by standing for 5-10 minutes.

[0025] Furthermore, the solvent used for washing to neutrality in step 4) is one or both of methanol and ethanol, and the washing is performed 2 to 4 times.

[0026] Furthermore, in step 4), the drying is performed by vacuum drying at a temperature of 60° C. for a period of 6-12 hours.

[0027] Furthermore, in step 5), the inert atmosphere is selected from nitrogen, helium or argon; the calcination temperature is 600-1200° C., the heating rate is 300-600° C. / s, and the calcination time is 0.5-5 h.

[0028] In a second aspect, the present invention provides a Cu-M two-component single-atom catalyst prepared according to the preparation method described in the first aspect.

[0029] The Cu-M two-component single-atom catalyst has a three-dimensional pore structure, a high specific surface area, rich atomic pairs on the material surface, and a diverse microstructure. The microstructure of the prepared catalyst is different depending on the selection of different precursors, non-precious metals, imidazoles and solvents.

[0030] In a third aspect, the present invention provides an application of the Cu-M two-component single-atom catalyst described in the second aspect in the reaction of selective hydrogenation of acetylene to produce ethylene.

[0031] Furthermore, the reaction of selective hydrogenation of acetylene to produce ethylene is carried out as follows: in a fixed bed reactor, the Cu-M two-component single-atom catalyst is loaded, a raw gas containing acetylene and hydrogen is introduced, and ethylene is generated under the conditions of a reaction temperature of 170 to 220° C. and a reaction pressure of 0.1 to 0.5 MPa.

[0032] Furthermore, the ratio of the amounts of substances in the raw gas is n(H2) / n(C2H2)=2~2.2 / 1.

[0033] Furthermore, the raw gas also contains ethylene and a carrier gas, and the carrier gas is preferably nitrogen.

[0034] Furthermore, the acetylene gas space velocity is 6000~20000h -1 .

[0035] The Cu-M dual-component single-atom catalyst prepared by the present invention has good reaction activity in the above-mentioned acetylene selective hydrogenation reaction, and the acetylene conversion rate can reach up to 97%, and the ethylene selectivity can reach up to 97.5%.

[0036] Compared with the prior art, the present invention has the following innovations and technical advantages:

[0037] (1) The present invention uses ZIF-8 material as a carrier, which has a three-dimensional pore structure. This structure enables ZIF-8 to have a large specific surface area and pore volume, and can adsorb and store gases, liquids and other molecular substances.

[0038] (2) The present invention adopts ball milling to assist in controlling the catalyst particle size, and the particle size distribution is very uniform.

[0039] (3) The present invention adopts ultra-gravity assisted crystallization and ultra-gravity assisted coating methods to prepare the copper salt and the non-precious metal M salt on the surface of the ZIF-8 material according to a specific self-assembly sequence. After coating, it is first pickled to produce defects, and then calcined by Joule heating technology, which has high heating efficiency and low energy consumption, so that the active components are more evenly distributed on the carrier, thereby obtaining a Cu-M two-component single-atom catalyst.

[0040] (4) The Cu-M two-component single-atom catalyst prepared by the present invention is applied to the selective hydrogenation reaction of acetylene. At a relatively low reaction temperature, the acetylene conversion rate is high, the ethylene selectivity is good, and the stability is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a TEM image of the catalyst prepared in Example 4, which shows that the metal atoms on the catalyst surface are in a single-atom dispersion state.

[0042] Figure 2 This is a synchrotron radiation R-space data diagram of the catalyst prepared in Example 4. The synchrotron radiation R-space data show that both Cu and Ni in the catalyst are coordinated with nitrogen atoms and there are no metallic bonds, which further proves the single-atom dispersion state of the metal components in the catalyst. DETAILED DESCRIPTION

[0043] The present invention is described below with specific examples. It is necessary to point out that the examples are only used to further illustrate the present invention, but cannot be understood as limiting the scope of protection of the present invention, and the present invention is not limited thereto in any way. Those skilled in the art in this field can make some non-essential improvements and adjustments based on the content of the above invention.

[0044] If no specific conditions are specified in the examples of the present invention, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be obtained by conventional technical means or purchased commercially.

[0045] Example 1

[0046] 1) Weigh 4.39 g of zinc acetate dihydrate and 6.21 g of 2-methylimidazole and dissolve them in 160 mL of ethanol to obtain zinc acetate solution 1 and 2-methylimidazole solution, respectively; weigh 0.20 g of copper acetate monohydrate and 0.22 g of zinc acetate dihydrate and dissolve them in 40 mL of ethanol to obtain copper acetate solution and zinc acetate solution 2, respectively;

[0047] 2) adding the 2-methylimidazole solution in step 1) to the ethanol solution 1 of zinc acetate, mixing rapidly in a supergravity reactor, and reacting at 200 rpm and 30° C. for 6 h to generate a ZIF-8 suspension;

[0048] 3) filtering the ZIF-8 solution obtained in step 1), washing with ethanol three times, and drying in a vacuum drying oven at 60° C. for 12 h to obtain ZIF-8 powder;

[0049] 4) milling the powder obtained in step 3) in a ball mill for 30 min at a rotation speed of 200 rpm to obtain ZIF-8 powder with uniform particle size;

[0050] 5) 40 mL of the ethanol solution of copper acetate and 40 mL of the ethanol solution of zinc acetate 2 in step 1) were rapidly mixed with 5 g of ZIF-8 powder in a supergravity reactor, and reacted at 200 rpm and 30° C. for 6 h to generate a Cu-Zn@ZIF-8 suspension;

[0051] 6) The above solution was centrifuged at 15000 rpm for 5 min, the light blue product was collected, and washed twice with DMF and methanol respectively;

[0052] 7) The material obtained by the above centrifugal washing treatment was vacuum dried at 60° C. for 6 h to obtain Cu-Zn@ZIF-8;

[0053] 8) The Cu-Zn@ZIF-8 sample obtained by the above vacuum drying treatment was treated with 0.50M sulfuric acid for 10 minutes, washed twice with methanol, and then vacuum dried at 60°C for 12 hours to obtain the product Cu-Zn@ZIF-8;

[0054] 9) placing the vacuum dried powder in a Joule heater and heating it in a nitrogen atmosphere at a heating rate of 300°C / s, with a calcination temperature of 600°C and a calcination time of 3h to obtain a Cu-Zn / NC two-component single atom catalyst;

[0055] 10) Evaluation of acetylene selective hydrogenation reaction in fixed bed reactor: Acetylene selective hydrogenation reaction at 170°C, acetylene space velocity 6000h -1 , a mixed gas containing 0.33% acetylene, 0.66% H2 and 33% ethylene (nitrogen as carrier gas) was used at a flow rate of 30 mL / min; the reaction conversion rate was 97% and the ethylene selectivity was 97.5%.

[0056] Example 2

[0057] 1) Weigh 4.39 g of zinc acetate dihydrate and 9.31 g of 4-methylimidazole and dissolve them in 160 mL of ethanol to obtain a zinc acetate solution and a 2-methylimidazole solution, and weigh 0.25 g of copper nitrate trihydrate and 0.50 g of manganese nitrate tetrahydrate and dissolve them in 40 mL of ethanol to obtain a copper nitrate solution and a manganese nitrate solution;

[0058] 2) slowly adding the 2-methylimidazole solution in step 1) to the ethanol solution of zinc acetate, rapidly mixing in a high gravity reactor, and reacting at 200 rpm and 30° C. for 6 h to generate a ZIF-8 suspension;

[0059] 3) filtering the ZIF-8 solution obtained in step 1), washing with methanol for 3 times, and drying in a vacuum drying oven at 80° C. for 12 h to obtain ZIF-8 powder;

[0060] 4) milling the powder obtained in step 3) in a ball mill for 30 min at a rotation speed of 200 rpm to obtain ZIF-8 powder with uniform particle size;

[0061] 5) adding 40 mL of the ethanol solution of copper nitrate and 40 mL of the ethanol solution of manganese nitrate in step 1) to 5 g of ZIF-8 powder, rapidly mixing in a supergravity reactor at 200 rpm and 60° C. for 6 h to generate a Cu-Mn@ZIF-8 suspension;

[0062] 6) The above solution was centrifuged at 15000 rpm for 5 min, the light blue product was collected, and washed twice with DMF and methanol respectively to obtain Cu-Mn@ZIF-8;

[0063] 7) The material obtained by the above centrifugal washing treatment was vacuum dried at 60° C. for 8 h to obtain Cu-Mn@ZIF-8 powder;

[0064] 8) The Cu-Mn@ZIF-8 sample obtained by the above vacuum drying treatment was treated with 0.5M sulfuric acid for 8 minutes, washed twice with methanol, and then vacuum dried at 60°C for 10 hours to obtain the product Cu-Mn@ZIF-8;

[0065] 9) placing the vacuum dried powder in a Joule heater and heating it in a helium atmosphere at a heating rate of 300°C / s, with a calcination temperature of 1100°C and a calcination time of 3.5h to obtain a Cu-Mn / NC two-component single atom catalyst;

[0066] 10) Evaluation of acetylene selective hydrogenation reaction in fixed bed reactor: Acetylene selective hydrogenation reaction at 170°C, acetylene space velocity 6000h -1 , a mixed gas containing 0.33% acetylene, 0.66% H2 and 33% ethylene (nitrogen as carrier gas) was used at a flow rate of 30 mL / min; the reaction conversion rate was 48% and the ethylene selectivity was 95.7%.

[0067] Example 3

[0068] 1) Weigh 4.39 g of zinc acetate dihydrate and 6.21 g of 2-methylimidazole and dissolve them in 160 mL of ethanol to obtain a zinc acetate solution and a 2-methylimidazole solution, respectively; weigh 0.20 g of copper acetate monohydrate and 0.25 g of cobalt acetate tetrahydrate and dissolve them in 40 mL of ethanol to obtain a copper acetate solution and a cobalt acetate solution, respectively;

[0069] 2) slowly adding the 2-methylimidazole solution in step 1) to the ethanol solution of zinc acetate, rapidly mixing in a supergravity reactor, and reacting at 200 rpm and 40° C. for 12 h to generate a ZIF-8 suspension;

[0070] 3) filtering the ZIF-8 solution obtained in step 1), washing with deionized water for 3 times, and drying in a vacuum drying oven at 60° C. for 12 h to obtain ZIF-8 powder;

[0071] 4) The powder obtained in step 3) was ball-milled in a ball mill for 1 h at a rotation speed of 200 rpm to obtain ZIF-8 powder with uniform particle size;

[0072] 5) adding 40 mL of the ethanol solution of copper acetate and 40 mL of the ethanol solution of cobalt acetate in step 1) to 5 g of ZIF-8 powder, rapidly mixing in a supergravity reactor at 200 rpm and 70° C. for 24 h to generate a Cu-Co@ZIF-8 suspension;

[0073] 6) The above solution was centrifuged at 10000 rpm for 10 min, the light blue product was collected, and washed twice with DMF and methanol respectively;

[0074] 7) The material obtained by the above centrifugal washing treatment was vacuum dried at 60° C. for 12 h to obtain Cu-Co@ZIF-8 powder;

[0075] 8) The Cu-Co@ZIF-8 sample obtained by the above vacuum drying treatment was treated with 0.5M nitric acid for 5 minutes, washed twice with ethanol, and then vacuum dried at 60°C for 12 hours to obtain the pure product Cu-Co@ZIF-8;

[0076] 9) placing the vacuum dried powder in a Joule heater and heating it in a nitrogen atmosphere at a heating rate of 300°C / s, with a calcination temperature of 1000°C and a calcination time of 4h to obtain a Cu-Co / NC two-component single atom catalyst;

[0077] 10) Evaluation of acetylene selective hydrogenation reaction in fixed bed reactor: Acetylene selective hydrogenation reaction at 170°C, acetylene space velocity 6000h -1 , a mixed gas containing 0.33% acetylene, 0.66% H2 and 33% ethylene (nitrogen as carrier gas) was used at a flow rate of 30 mL / min; the reaction conversion rate was 68% and the ethylene selectivity was 96.5%.

[0078] Example 4

[0079] 1) Weigh 4.39 g of zinc acetate dihydrate and 6.21 g of 2-methylimidazole and dissolve them in 160 mL of deionized water to obtain a zinc acetate aqueous solution and a 2-methylimidazole aqueous solution, and weigh 0.20 g of copper acetate monohydrate and 0.25 g of nickel acetate tetrahydrate and dissolve them in 40 mL of deionized water to obtain a copper acetate solution and a nickel acetate solution;

[0080] 2) slowly adding the 2-methylimidazole aqueous solution in step 1) to the zinc acetate aqueous solution, rapidly mixing in a supergravity reactor, and reacting at 200 rpm and 30° C. for 12 h to generate a ZIF-8 suspension;

[0081] 3) filtering the ZIF-8 solution obtained in step 1), washing with ethanol three times, and drying in a vacuum drying oven at 50° C. for 12 h to obtain ZIF-8 powder;

[0082] 4) milling the powder obtained in step 3) in a ball mill for 30 min at a rotation speed of 200 rpm to obtain ZIF-8 powder with uniform particle size;

[0083] 5) adding 40 mL of the aqueous solution of copper acetate and 40 mL of the aqueous solution of nickel acetate in step 1) to 5 g of ZIF-8 powder, rapidly mixing in a supergravity reactor at 200 rpm and 30° C. for 12 h to generate a Cu-Ni@ZIF-8 suspension;

[0084] 6) The above solution was centrifuged at 15000 rpm for 5 min, the light blue product was collected, and washed twice with DMF and methanol respectively;

[0085] 7) The material obtained by the above centrifugal washing treatment was vacuum dried at 60° C. for 10 h to obtain Cu-Ni@ZIF-8;

[0086] 8) The Cu-Ni@ZIF-8 sample obtained by the above vacuum drying treatment was treated with 0.5M nitric acid for 7 minutes, washed twice with methanol, and then vacuum dried at 60°C for 10 hours to obtain the product Cu-Ni@ZIF-8-defect;

[0087] 9) placing the vacuum dried powder in a Joule heater and heating it in a nitrogen atmosphere at a heating rate of 300°C / s, with a calcination temperature of 1000°C and a calcination time of 3.5h to obtain a Cu-Ni / NC two-component single atom catalyst;

[0088] 10) Evaluation of acetylene selective hydrogenation reaction in fixed bed reactor: Acetylene selective hydrogenation reaction at 170°C, acetylene space velocity 6000h -1 , a mixed gas containing 0.33% acetylene, 0.66% H2 and 33% ethylene (nitrogen as carrier gas) was used at a flow rate of 30 mL / min; the reaction conversion rate was 96.7% and the ethylene selectivity was 97.9%.

[0089] Example 5

[0090] 1) Weigh 5.41 g of zinc nitrate dihydrate and 7.24 g of 3-methylimidazole and dissolve them in 160 mL of ethanol to obtain an ethanol solution of zinc acetate and an ethanol solution of 3-methylimidazole, weigh 0.24 g of copper nitrate trihydrate and 0.40 g of ferric nitrate nonahydrate and dissolve them in 40 mL of ethanol to obtain an ethanol solution of copper nitrate and an ethanol solution of ferric nitrate;

[0091] 2) slowly adding the ethanol solution of 3-methylimidazole in step 1) to the ethanol solution of zinc nitrate, rapidly mixing in a supergravity reactor, and reacting at 200 rpm and 30° C. for 15 h to generate a ZIF-8 suspension;

[0092] 3) filtering the ZIF-8 solution obtained in step 1), washing with acetonitrile for 3 times, and drying in a vacuum drying oven at 60° C. for 12 h to obtain ZIF-8 powder;

[0093] 4) The powder obtained in step 3) was ball-milled in a ball mill for 1 h at a rotation speed of 200 rpm to obtain ZIF-8 powder with uniform particle size;

[0094] 5) adding 40 mL of the ethanol solution of copper nitrate and 40 mL of the ethanol solution of iron nitrate in step 1) to 5 g of ZIF-8 powder, rapidly mixing in a supergravity reactor at 200 rpm and 50° C. for 24 h to generate a Cu-Fe@ZIF-8 suspension;

[0095] 6) Centrifuge the above solution at 15000 rpm for 15 min, collect the obtained light blue product, and wash it twice with DMF and methanol respectively;

[0096] 7) The material obtained by the above centrifugal washing treatment was vacuum dried at 60° C. for 6 h to obtain Cu-Fe@ZIF-8 powder;

[0097] 8) The Cu-Fe@ZIF-8 sample obtained by the above vacuum drying treatment was treated with 0.5M nitric acid for 8 minutes, washed twice with ethanol, and then vacuum dried at 60°C for 6 hours to obtain the pure product Cu-Fe@ZIF-8;

[0098] 9) placing the vacuum dried powder in a Joule heating apparatus and heating it in a nitrogen atmosphere at a heating rate of 300°C / s, with a calcination temperature of 1000°C and a calcination time of 4h to obtain a Cu-Fe / NC two-component single atom catalyst;

[0099] 10) Evaluation of acetylene selective hydrogenation reaction in fixed bed reactor: Acetylene selective hydrogenation reaction at 170°C, acetylene space velocity 6000h -1 , a mixed gas containing 0.33% acetylene, 0.66% H2 and 33% ethylene (nitrogen as carrier gas) was used at a flow rate of 30 mL / min; the reaction conversion rate was 60% and the ethylene selectivity was 80%.

[0100] Example 6

[0101] 1) Weigh 2.75 g of anhydrous zinc chloride and 7.24 g of 2-methylimidazole and dissolve them in 160 mL of acetone to obtain an acetone solution of zinc chloride and an acetone solution of 2-methylimidazole, and weigh 0.15 g of anhydrous cupric chloride and 0.23 g of anhydrous zirconium chloride and dissolve them in 50 mL of acetone to obtain an acetone solution of cupric chloride and an acetone solution of zirconium chloride;

[0102] 2) slowly adding the acetone solution of 2-methylimidazole in step 1) to the acetone solution of zinc chloride, rapidly mixing in a supergravity reactor, and reacting at 200 rpm and 40° C. for 24 h to generate a ZIF-8 suspension;

[0103] 3) filtering the ZIF-8 solution obtained in step 1), washing with ethanol three times, and drying in a vacuum drying oven at 60° C. for 12 h to obtain ZIF-8 powder;

[0104] 4) The powder obtained in step 3) was ball milled in a ball mill for 1 h at a speed of 200 rpm to obtain ZIF-8 powder with uniform particle size.

[0105] 5) adding 50 mL of the acetone solution of copper chloride and 50 mL of the acetone solution of zirconium chloride in step 1) to 5 g of ZIF-8 powder, mixing rapidly in a supergravity reactor at 200 rpm and 35° C. for 12 h to generate a Cu-Zr@ZIF-8 suspension;

[0106] 6) The above solution was centrifuged at 10000 rpm for 12 min, the light blue product was collected, and washed twice with DMF and methanol respectively;

[0107] 7) The material obtained by the above centrifugal washing treatment was vacuum dried at 60° C. for 8 h to obtain Cu-Zr@ZIF-8 powder;

[0108] 8) The Cu-Zr@ZIF-8 sample obtained by the above vacuum drying treatment was treated with 0.5M hydrochloric acid for 6 minutes, washed twice with methanol, and then vacuum dried at 60°C for 8 hours to obtain the product Cu-Zr@ZIF-8-defect;

[0109] 9) placing the vacuum dried powder in a Joule heater and heating it in an argon atmosphere at a heating rate of 300°C / s, with a calcination temperature of 900°C and a calcination time of 5h to obtain a Cu-Zr / NC two-component single atom catalyst;

[0110] 10) Evaluation of acetylene selective hydrogenation reaction in fixed bed reactor: Acetylene selective hydrogenation reaction at 170°C, acetylene space velocity 6000h -1 , a mixed gas containing 0.33% acetylene, 0.66% H2 and 33% ethylene (nitrogen as carrier gas) was used at a flow rate of 30 mL / min; the reaction conversion rate was 63% and the ethylene selectivity was 86%.

[0111] Example 7

[0112] 1) Weigh 2.75 g of anhydrous zinc chloride and 7.24 g of 2-methylimidazole and dissolve them in 160 mL of acetone to obtain an acetone solution of zinc chloride and an acetone solution of 2-methylimidazole, weigh 0.15 g of anhydrous cupric chloride and 0.16 g of anhydrous chromium chloride and dissolve them in 60 mL of acetone to obtain an acetone solution of cupric chloride and an acetone solution of chromium chloride;

[0113] 2) slowly adding the acetone solution of 2-methylimidazole in step 1) to the acetone solution of zinc chloride, rapidly mixing in a supergravity reactor, and reacting at 200 rpm and 45° C. for 12 h to generate a ZIF-8 suspension;

[0114] 3) filtering the ZIF-8 solution obtained in step 1), washing with acetonitrile for 3 times, and drying in a vacuum drying oven at 60° C. for 12 h to obtain ZIF-8 powder;

[0115] 4) The powder obtained in step 3) was ball-milled in a ball mill for 1 h at a rotation speed of 200 rpm to obtain ZIF-8 powder with uniform particle size;

[0116] 5) adding 60 mL of the acetone solution of copper chloride and 60 mL of the acetone solution of chromium chloride in step 1) to 5 g of ZIF-8 powder, rapidly mixing in a supergravity reactor at 300 rpm and 60° C. for 12 h to generate a Cu-Cr@ZIF-8 suspension;

[0117] 6) The above solution was centrifuged at 10000 rpm for 10 min, the light blue product was collected, and washed twice with DMF and methanol respectively;

[0118] 7) The material obtained by the above centrifugal washing treatment was vacuum dried at 60° C. for 12 h to obtain Cu-Cr@ZIF-8 powder;

[0119] 8) The Cu-Cr@ZIF-8 sample obtained by the above vacuum drying treatment was treated with 0.5M hydrochloric acid for 5 minutes, washed twice with methanol, and then vacuum dried at 60°C for 12 hours to obtain the product Cu-Cr@ZIF-8-defect;

[0120] 9) placing the vacuum dried powder in a Joule heater and heating it in an argon atmosphere at a heating rate of 300°C / s, with a calcination temperature of 900°C and a calcination time of 5h to obtain a Cu-Cr / NC two-component single atom catalyst;

[0121] 10) Evaluation of acetylene selective hydrogenation reaction in fixed bed reactor: Acetylene selective hydrogenation reaction at 170°C, acetylene space velocity 6000h -1 , a mixed gas containing 0.33% acetylene, 0.66% H2 and 33% ethylene (nitrogen as carrier gas) was used at a flow rate of 30 mL / min; the reaction conversion rate was 95.8% and the ethylene selectivity was 96.1%.

[0122] Comparative Example 1

[0123] Comparison of Comparative Example 1 with Example 1 shows that the copper and zinc elements in the catalyst exist in the form of an alloy, and the acetylene conversion rate can reach 98%, but the ethylene selectivity is relatively low.

[0124] 1) Preparation of copper-zinc alloy catalyst CuZn NPs / AC: 5.4 mg CuCl2, 5.4 mg ZnCl2, 5 mL HCl and 6.6 mg PEG1000 were mixed in a 50 mL flask, and then the mixture was heated to 160°C in an oil bath and maintained for 5 h to obtain a copper-zinc alloy. The prepared Cu-Zn alloy was made into an impregnation solution with 10 mL deionized water, and 5 g of commercially purchased carbon support (Chengde Slepu Activated Carbon Manufacturing Co., Ltd., amorphous particles, mesh size 6, product type: native carbon) was poured into the impregnation solution and impregnated at room temperature for 12 h, and then calcined at 300°C for 4 h in a nitrogen environment, and then reduced at 400°C for 2 h in 5% H2 / Ar to obtain a copper-zinc alloy catalyst CuZn NPs / AC.

[0125] 2) Evaluation of acetylene selective hydrogenation reaction in fixed bed reactor: Acetylene selective hydrogenation reaction at 80-240°C, acetylene space velocity 6000h -1 , a mixed gas containing 0.33% acetylene, 0.66% H2 and 33% ethylene (nitrogen as carrier gas) was used at a flow rate of 30 mL / min; when the temperature was 170°C, the reaction conversion rate was 98% and the ethylene selectivity was 75%.

[0126] Comparative Example 2

[0127] Comparison of Comparative Example 2 with Example 1 shows that the copper and zinc atoms in the catalyst of Comparative Example 2 exist in the form of diatomic coordinated sites, and the acetylene conversion rate in the reaction at 170° C. is relatively low.

[0128] 1) Prepare Cu-Zn / NC2 diatomic catalyst according to the document "ACS Catal.2024,14,6,3900-3911".

[0129] 2) Evaluation of acetylene selective hydrogenation reaction in a fixed bed reactor: Acetylene selective hydrogenation reaction at 80-240°C, acetylene space velocity 6000h -1 , a mixed gas containing 0.33% acetylene, 0.66% H2 and 33% ethylene (nitrogen as carrier gas) was used at a flow rate of 30 mL / min; when the temperature was 170°C, the reaction conversion rate was 83% and the ethylene selectivity was 97%.

[0130] Table 1. Catalytic performance of acetylene hydrogenation over different non-precious metal catalysts

[0131]

[0132]

Claims

1. A method for preparing a Cu-M two-component single-atom catalyst, characterized in that: The M non-precious metal is selected from at least one of zinc, nickel and chromium, and the preparation method comprises the following steps: 1) Dissolve zinc salt, copper salt, non-noble metal M salt and imidazole compound in solvent A respectively according to a certain proportion; 2) slowly adding the imidazole compound solution obtained in step 1) into the Zn salt solution, placing the mixed solution in a high gravity reactor for reaction, and allowing the imidazole and zinc salt to self-assemble into a ZIF-8 structure in solvent A, and filtering, washing, drying, and grinding to obtain ZIF-8 powder with uniform particle size; 3) Mixing the copper salt solution and the non-precious metal M salt solution obtained in step 1) with the ZIF-8 powder obtained in step 2), and placing them in a supergravity reactor again for stirring reaction, wherein the Cu salt and the non-precious metal M salt and imidazole are assembled on the surface of ZIF-8 and cover ZIF-8, and then separated, washed and dried to obtain Cu-M@ZIF-8; the feeding ratio of the copper salt solution and the non-precious metal M salt solution is based on the element molar ratio of copper:M=1:1-1:2, and the feeding ratio of the copper salt solution to the ZIF-8 powder is 1mmol:3-5g in terms of the ratio of the molar number of the copper element to the mass of the ZIF-8 powder; 4) The Cu-M@ZIF-8 sample obtained in step 3) is treated with acid, washed to neutrality, and dried to obtain Cu-M@ZIF-8 containing defects; 5) The defective Cu-M@ZIF-8 sample obtained in step 4) is calcined in an inert atmosphere using a Joule heater to obtain a Cu-M two-component single-atom catalyst.

2. The preparation method according to claim 1, characterized in that: The non-precious metal M salt described in step 1) is selected from one or more of acetate, nitrate and chloride.

3. The preparation method according to claim 1, characterized in that: The imidazole compound described in step 1) is selected from one or more of 4-methylimidazole, 3-methylimidazole, and 2-methylimidazole.

4. The preparation method according to claim 1, characterized in that: The solvent A in step 1) is selected from deionized water, methanol, ethanol or acetone.

5. The preparation method according to claim 1, characterized in that: Step 2) The reaction conditions in the ultra-gravity reactor are: temperature of 25-70°C, rotation speed of 100-600 rpm, and time of 6 to 24 hours.

6. The preparation method according to claim 1, characterized in that: The reaction conditions of the high gravity reactor in step 3) are: temperature of 25-70°C, rotation speed of 100-600 rpm, and time of 6 to 24 hours.

7. The preparation method according to claim 1, characterized in that: The acid in step 4) is selected from one of sulfuric acid, hydrochloric acid and nitric acid, the acid concentration is 0.3-0.5M, and the pickling is performed by standing for 5-10 minutes.

8. The preparation method according to claim 1, characterized in that: In step 5), the inert atmosphere is selected from nitrogen, helium or argon; the calcination temperature is 600-1200° C., the heating rate is 300-600° C. / s, and the calcination time is 0.5-5 h.

9. The Cu-M two-component single-atom catalyst prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the Cu-M two-component single-atom catalyst as claimed in claim 9 in the reaction of selective hydrogenation of acetylene to produce ethylene.

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