Method for preparing or regenerating supported noble metal monatomic catalyst by using olefin

Abstract

The invention belongs to the technical field of chemical engineering, and relates to a method for preparing and regenerating a supported monatomic catalyst by using olefin. The preparation method comprises the following steps: (1) loading noble metal on a carrier through an impregnation method, a coprecipitation method or an in-situ synthesis method; (2) treating the catalyst in an H2 atmosphere; and (3) treating the catalyst in an olefin atmosphere or an olefin solution to obtain the supported monatomic catalyst. The regeneration method comprises the following steps: (1) roasting an inactivated catalyst to remove carbon deposition formed in a catalysis process, and reducing in an H2 atmosphere; and (2) treating the catalyst in an olefin atmosphere or an olefin solution to obtain the regenerated supported monatomic catalyst. According to the present invention, the noble metal particles with the average particle size of less than 2 nm are dispersed by using the olefin to obtain the sub-nano-scale dispersed or even monatomic-scale dispersed supported noble metal catalyst, and the catalyst can be regenerated by using the method, such that the large-scale application in the industrial production can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts and relates to a method for preparing and regenerating a supported single-atom catalyst by utilizing olefins. Background Art

[0002] Since the concept of single-atom catalysts was proposed by the research group of Academician Zhang Tao in 2011 (Nat. Chem., 2011, 3: 634), single-atom catalysts have attracted close attention due to their high catalytic activity and unique selectivity, and this field has also developed rapidly. Currently, the more mature methods for preparing single-atom catalysts include atomic layer deposition, impregnation, co-precipitation, deposition precipitation, strong electrostatic adsorption, and selective dissolution of nanoparticles (J. Am. Chem. Soc., 2013, 135: 15314; Science, 2014, 346: 1498; Science, 2014, 344: 616; J. Am. Chem. Soc., 2015, 137: 10484). Among them, based on the widespread dispersion phenomenon of precious metals such as Pd, Pt, and Rh in CO and NO atmospheres (ACS. Catal., 2023, 13: 1197; J. Phys. Chem., 2014, 118: 9588; J. Am. Chem. Soc., 2013, 135: 1760), our group proposed a new universal method for preparing highly dispersed precious metal catalysts, that is, using CO, NO and other gas atmospheres to induce metal particles to disperse on the carrier as single-atom catalysts (CN111215053A). This method is simple in process and the utilization rate of metal atoms is as high as 100%, which is conducive to large-scale application in industrial production.

[0003] As an important raw material for industrial processes, olefins can be converted into a variety of downstream products through cracking, hydrogenation, oxidation and other means. For example, the hydroformylation reaction of olefins can be converted into compounds such as carboxylic acids, esters, and alcohols under the action of single-atom catalysts. Our group has found through research in this field that high-concentration olefin conditions can stabilize single-atom catalysts, making them less likely to aggregate and lose, thereby achieving the purpose of long service life (CN114163318B). As early as 2008, Bruce C. Gates' research group found that Rh or Ir metal complexes aggregate into clusters with an average coordination number of about 2 in a high-concentration hydrogen atmosphere during the study of ethylene hydrogenation / dimerization reactions, and that clusters disperse into highly dispersed monomers in a high-concentration ethylene atmosphere (J. Am. Chem. Soc., 2009, 131: 15887; J. Phys. Chem. C., 2008, 112: 18039). However, the research on this phenomenon did not propose a specific dispersion mechanism, and only stayed at the ethylene reaction stage, and did not expand its application. Summary of the invention

[0004] The present invention discloses a new method for preparing a supported single-atom catalyst by using olefin-dispersed metal particles, which is universally applicable to precious metals such as Rh, Ru, Pd, Pt and Ir.

[0005] Another object of the present invention is to provide a new regeneration and activation method for precious metals such as Rh, Ru, Pd, Pt, and Ir, which uses olefin treatment to achieve dispersed regeneration of particles with a particle size of less than 2 nm into supported single-atom catalysts.

[0006] To achieve the above-mentioned purpose, the scheme provided by the present invention is that the catalyst consists of a carrier and an active metal, the metal is one or more of Rh, Ru, Pd, Pt, Ir, the carrier is one or more of CeO2, Al2O3, TiO2, MgO, SiO2, MFI type molecular sieve, Fe2O3, mesoporous carbon material CMK-3, activated carbon, triphenylphosphine resin, the total metal loading concentration is 10-0.01wt%, and a highly dispersed supported single-atom catalyst is obtained after treatment with olefins.

[0007] A method for preparing and regenerating supported single-atom catalysts using olefins:

[0008] The preparation method comprises the following steps: (1) loading the precious metal onto the carrier by impregnation, coprecipitation or in-situ synthesis; (2) placing the catalyst in a H2 atmosphere for treatment; (3) treating the catalyst in an olefin atmosphere or an olefin solution to obtain a loaded single-atom catalyst.

[0009] The regeneration method comprises the following steps: (1) calcining the deactivated catalyst to remove the carbon deposits formed during the catalytic process, and reducing the catalyst in a H2 atmosphere; and (2) treating the catalyst in an olefin atmosphere or an olefin solution to obtain a regenerated supported single-atom catalyst.

[0010] The catalyst preparation process is as follows:

[0011] (1) Taking the chloride, nitrate, or organic complex of noble metals such as Rh, Ru, Pd, Pt, or Ir as precursors, a certain amount of one or more of the precursors is dissolved in water or a common organic solution, and then an appropriate amount of inorganic or organic reagent is added to obtain a noble metal precursor solution. Common organic solutions include: a mixture of any ratio of one or more of DMF, DMSO, acetonitrile, toluene, methanol, ethanol, acetone, dichloromethane, tetrahydrofuran, cyclohexane, isopropanol, and 1,4-dioxane.

[0012] Common inorganic reagents are: ammonium phosphite, ammonium phosphate, ammonium sulfite, ammonium sulfate, ammonium chloride, ammonium nitrate, and ammonia water, one or more of which are mixed in any ratio.

[0013] Common organic reagents include: one or more of ethylenediamine, diethylamine, aniline, acetamide, ethanolamine, EDTA, triphenylphosphine, triethyl phosphate, cystine, and cysteine ​​in any ratio.

[0014] (2) The noble metal precursor solution in step (1) is loaded on one or more supports selected from CeO2, Al2O3, TiO2, MgO, SiO2, MFI molecular sieve, Fe2O3, mesoporous carbon material CMK-3, activated carbon, triphenylphosphine resin by impregnation, coprecipitation or in-situ synthesis to obtain a loaded noble metal catalyst precursor. The total loading of the noble metal is 10-0.01wt% (preferably 5-0.01wt%, more preferably 2-0.01wt%).

[0015] (3) The supported noble metal catalyst precursor obtained in step (2) is passed through a hydrogen atmosphere with a volume fraction of 10-100 vol% (preferably 15-100 vol%, more preferably 20-100 vol%), wherein the hydrogen atmosphere contains balance gas other than hydrogen, and the balance gas is one or more of N2, Ar, and He, and is treated at 20-300°C (preferably 50-200°C, more preferably 80-150°C) for 1-120 min (preferably 2-90 min, more preferably 2-60 min), to obtain noble metal clusters or particles with greater than or equal to 2 atoms and a diameter of less than or equal to 2.5 nm (preferably less than or equal to 2.3 nm, more preferably less than or equal to 2 nm) in the treated supported catalyst.

[0016] (4) the supported catalyst obtained in step (3) is subjected to a gas roasting treatment at a temperature of 20-300° C. (preferably 20-250° C., more preferably 20-200° C.) for 10-180 min (preferably 10-150 min, more preferably 10-120 min) at a mass concentration of 20-100 wt% (preferably 15-100 vol%, more preferably 20-100 vol%) of olefin atmosphere, wherein the olefin atmosphere contains a balance gas other than olefin, and the balance gas is one or more of N2, Ar, He, H2, and CH4; or Preferably 30-100wt%, more preferably 50-100wt%) of olefin solution, the rest of the olefin solution except olefin is a balance liquid, the balance liquid is one or more of cyclohexane, toluene, benzene, N,N-dimethylformamide, 1,4-dioxane, straight-chain alkane, tetrahydrofuran, dichloromethane, methanol, ethanol, acetone, acetonitrile, isopropanol, the solution is stirred at a temperature of 20-200°C (preferably 20-180°C, more preferably 20-150°C) for 10-180min (preferably 10-150min, more preferably 10-120min) to obtain a newly prepared supported single-atom catalyst. The olefin atmosphere is one or more of ethylene, propylene, butene, butadiene. The olefin liquid is C4-C 10 One or more of mono-olefins and di-olefins.

[0017] The catalyst regeneration process is as follows:

[0018] (1) The deactivated supported noble metal catalyst is calcined at 100-600° C. (preferably 150-550° C., more preferably 200-550° C.) in an atmosphere of air and / or 10-90 vol% (preferably 15-85 vol%, more preferably 20-80 vol%) O2 / inert gas for 30-240 min (preferably 30-210 min, more preferably 30-180 min) to remove carbon deposits formed during the catalytic process, wherein the inert gas is one or more of N2, He, and Ar, and the catalyst is heated to 100 vol% (preferably 150-550 vol%) by a heating process. 1%, more preferably 20-100vol%), in which the rest of the hydrogen atmosphere is a balance gas except hydrogen, and the balance gas is one or more of N2, Ar, and He, and treated at 20-300°C (preferably 50-200°C, more preferably 80-150°C) for 1-120min (preferably 2-90min, more preferably 2-60min) to obtain a hydrogen-treated supported catalyst, wherein the catalyst contains noble metal clusters or particles with greater than or equal to 2 atoms and a diameter of less than or equal to 2.5nm (preferably less than or equal to 2.3nm, more preferably less than or equal to 2nm).

[0019] (2) the supported catalyst obtained in step (1) is subjected to a gas roasting treatment at a temperature of 20-300° C. (preferably 20-250° C., more preferably 20-200° C.) for 10-180 min (preferably 10-150 min, more preferably 10-120 min) at a mass concentration of 20-100 wt% (preferably 15-100 vol%, more preferably 20-100 vol%) of olefin atmosphere, wherein the olefin atmosphere contains a balance gas other than olefin, and the balance gas is one or more of N2, Ar, He, H2, and CH4; or The invention relates to a method for preparing a catalyst comprising the steps of: preparing a catalyst comprising: preparing an olefin solution having an olefin content of 100 wt % and a weight percentage of olefins, wherein the olefin solution contains an olefin in an amount of 30-100 wt %, more preferably 50-100 wt %), wherein the olefin solution contains an olefin in an amount of the rest being a balance liquid, wherein the balance liquid is one or more of cyclohexane, toluene, benzene, N,N-dimethylformamide, 1,4-dioxane, a straight-chain alkane, tetrahydrofuran, dichloromethane, methanol, ethanol, acetone, acetonitrile and isopropanol, and stirring the solution at a temperature of 20-200° C. (preferably 20-180° C., more preferably 20-150° C.) for 10-180 min (preferably 10-150 min, more preferably 10-120 min) to obtain a newly prepared supported single-atom catalyst.

[0020] The olefin atmosphere is one or more of ethylene, propylene, butene and butadiene.

[0021] Olefin liquid is C4-C 10 Monoolefins, C4-C 10 One or more of the dienes.

[0022] The present invention utilizes precious metal clusters or particles with an olefin dispersion diameter of less than or equal to 2.5 nm (preferably less than or equal to 2.3 nm, more preferably less than or equal to 2 nm) to obtain a single-atom-level dispersed supported precious metal catalyst, and the method can also be used to regenerate the catalyst, which can be used on a large scale in industrial production.

[0023] This discovery has the following effects:

[0024] Through this method, a highly dispersed precious metal catalyst with a metal atom utilization rate of up to 100% can be obtained. All metal atoms are exposed as active sites. It is a universal preparation and regeneration method and can be used on a large scale in industrial production, opening up a new preparation and regeneration path for the industrial application of single-atom catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the spherical aberration corrected HAADF-STEM image of the Pt1 / SiO2 catalyst in Example 1;

[0026] Figure 2This is the spherical aberration corrected HAADF-STEM image of the Ru1 / Al2O3 catalyst in Example 4;

[0027] Figure 3 This is the spherical aberration corrected HAADF-STEM image of the Ru1 / Al2O3 catalyst after regeneration in Example 7;

[0028] Figure 4 It is the HAADF-STEM image of the Pt / SiO2 catalyst in Comparative Example 1;

[0029] Figure 5 It is the HAADF-STEM image of the Ru / Al2O3 catalyst in Comparative Example 2; DETAILED DESCRIPTION

[0030] The following specific implementation modes are provided to further illustrate the present invention, but the present invention is not limited thereto.

[0031] Example 1: The noble metal is loaded by the impregnation method. 0.01g of platinum acetylacetonate is dissolved in 10g of ethanol, and 1g of silicon oxide powder is added. The powder is sieved through 100 mesh and has a diameter of less than 0.15mm. The powder is stirred for 6h, filtered and washed, and placed in an oven at 80°C for 12h to dry. A Pt / SiO2 catalyst precursor with a Pt loading of 0.5wt% of the whole is obtained. The precursor is then placed in a quartz tube and treated at 150°C for 15min in an 80vol% hydrogen / Ar balanced atmosphere to obtain a loaded Pt / SiO2 catalyst with an average particle size of 1.0nm and a particle size distribution range of less than or equal to 1.5nm. The catalyst is then treated at 120°C for 30min in an 80vol% ethylene / He balanced atmosphere to obtain a Pt1 / SiO2 catalyst in which the noble metal Pt is dispersed as a single atom. (As Figure 1 The Pt shown is loaded on the carrier SiO2 in the form of single atoms)

[0032] Example 2: The noble metal is loaded by the impregnation method. 0.017g palladium chloride is dissolved in 10g methanol, 2g triethyl phosphate organic reagent is added, and 1g mesoporous carbon material CMK-3 is added after stirring for 2h. The mixture is stirred for 8h, filtered and washed, and placed in an oven at 80°C for 12h to obtain a Pd / CMK-3 catalyst precursor with a Pd loading of 1wt% of the whole. The precursor is then placed in a quartz tube and treated at 200°C for 10min in a 50vol% hydrogen / N2 balanced atmosphere to obtain a noble metal particle with an average particle size of 1.8n m, a supported Pd / CMK-3 catalyst with a particle size distribution range of less than or equal to 4.2 nm, of which single-atom dispersion accounts for 12% (calculated based on the infrared CO adsorption peak fitting results), and then treated with 80wt% 1-pentene / cyclohexane equilibrium solution at 60°C for 45min to obtain a Pd1 / CMK-3 catalyst with a single-atom dispersion of 89% (calculated based on the infrared CO adsorption peak fitting results), wherein the remaining precious metal Pd particles have a particle size greater than 2.5nm and less than or equal to 4.2nm.

[0033] Example 3: The precious metal is loaded by the impregnation method. 0.01g of rhodium acetylacetonate is dissolved in 10g of 1,4-dioxane, and 1g of triphenylphosphine resin beads PPh3SP are added. The beads are sieved through 40 mesh and have a diameter of less than 0.45mm. They are stirred at 80°C for 8h, filtered and washed, and placed in an oven at 80°C for drying for 12h to obtain a Rh / PPh3SP catalyst precursor with a Rh loading of 0.5wt% of the whole. The precursor is then placed in a quartz tube and treated at 80°C for 5min in a 60vol% hydrogen / Ar balanced atmosphere to obtain a loaded Rh / PPh3SP catalyst with an average particle size of 0.8nm and a particle size distribution range of less than or equal to 1.2nm. The catalyst is then treated at 100°C for 30min in a propylene / Ar balanced atmosphere with a volume concentration of 80vol% to obtain a Rh1 / PPh3SP catalyst in which the precious metal Rh is dispersed as a single atom.

[0034] Example 4: The noble metal is loaded by the impregnation method. 0.018g of ruthenium chloride is dissolved in 10g of acetone, 1g of ammonium phosphate inorganic reagent is added, and 1g of Al2O3 powder is added after stirring for 2h. The powder is sieved through 100 mesh and the diameter is less than 0.15mm. Stir for 8h, filter and wash, and place in an oven at 80°C to dry for 12h to obtain a Ru / Al2O3 catalyst precursor with a Ru loading of 0.9wt% of the whole. The precursor is then placed in a quartz tube and treated at 200°C for 10min in a 100vol% hydrogen atmosphere to obtain a loaded Ru / Al2O3 catalyst with an average particle size of 0.9nm and a particle size distribution range of less than or equal to 1.6nm. Then, a 60vol% butene / He balanced atmosphere is used to treat at 150°C for 120min to obtain a Ru1 / Al2O3 catalyst in which the noble metal Ru is dispersed as a single atom. (As Figure 2 As shown, Ru is loaded on the carrier Al2O3 in the form of single atoms)

[0035] Example 5: Precious metals are loaded by the coprecipitation method. 0.027 g of chloroplatinic acid is dissolved in 10 g of water, 3 g of ferric nitrate is added, and the mixture is stirred evenly. The mixture is dripped into 60 mL of a solution containing 5.4 g of anhydrous sodium carbonate in a 50°C water bath, stirred for 3 h, allowed to stand for 3 h, washed and dried, and treated at 300°C in a 50 vol% hydrogen / N2 balanced atmosphere for 60 min to obtain precious metal particles with an average particle size of 1.1 nm, a particle size distribution range of less than or equal to 1.8 nm, and a Pt loading of 1 wt% of the total Pt / Fe2O3 catalyst. The catalyst is then treated at 150°C in a 50 vol% propylene / CH4 balanced atmosphere for 60 min to obtain a Pt1 / Fe2O3 catalyst in which the precious metal Pt is dispersed as a single atom.

[0036] Example 6: Using the in-situ synthesis method to load precious metals, 0.035g of iridium chloride was dissolved in 15g of water, 0.2g of ethylenediamine was added, stirred evenly, and 13g of 25wt% TPAOH solution and 8.4g tetraethyl orthosilicate solution were mixed and stirred for 6h. Then, the mixture was crystallized at 170°C for 3 days in a 100mL hydrothermal autoclave, centrifuged and washed, and then air-roasted at 550°C for 6h. The mixture was treated at 100°C for 10min in a 60vol% hydrogen / Ar equilibrium atmosphere to obtain a loaded Ir@S-1 catalyst with an average particle size of 1.8nm and a particle size distribution range of less than or equal to 3.2nm, and an Ir loading of 0.5wt% of the whole, of which the single-atom dispersion accounted for 16% (calculated based on the infrared CO adsorption peak fitting results). Then, the catalyst was treated at 150°C for 120min with 80wt% 1-hexene / cyclohexane equilibrium solution to obtain an Ir1@S-1 catalyst with a single-atom dispersion of 86% (calculated based on the infrared CO adsorption peak fitting results), and the particle size of the remaining precious metal Ir particles was greater than 2.8nm and less than or equal to 3.2nm.

[0037] Example 7: Ru / Al2O3 regeneration treatment. The catalyst in Example 4 was used for the selective hydrogenation reaction of nitrobenzene to obtain a used Ru / Al2O3 catalyst, wherein the Ru loading was 0.9wt%, and the Ru metal was partially agglomerated to form particles with an average particle size of 0.8nm and a particle size distribution of less than or equal to 1.3nm. The particles were calcined at 300°C in a 50vol% O2 / He balanced atmosphere for 30min to remove carbon deposits, and then treated at 50vol% hydrogen / He balanced atmosphere at 150°C for 10min to obtain a catalyst Ru / Al2O3 with an average particle size of 1.2nm and a particle size distribution range of less than or equal to 1.9nm. The catalyst was then treated at 150°C for 120min in a 60vol% butene / He balanced atmosphere to obtain a Ru1 / Al2O3 catalyst in which the precious metal Ru was dispersed as single atoms. (As shown in Figure 7: Ru / Al2O3 regeneration treatment. Figure 3 As shown, most of the Ru is loaded on the carrier Al2O3 in the form of single atoms. Although individual atoms are close to each other, all active sites are still exposed, and the atomic utilization rate is 100%, which can be identified as a single atom catalyst.

[0038] Example 8: Ir@S-1 regeneration treatment. The catalyst in Example 6 was used for propane dehydrogenation reaction to obtain the used Ir@S-1 catalyst, wherein the Ir loading was 0.5wt%, and the Ir metal was partially agglomerated to form particles with an average particle size of 1.5nm and a particle size distribution of less than or equal to 3.3nm. The catalyst was calcined at 300°C in a 30vol% O2 / Ar balanced atmosphere for 30min to remove carbon deposits, and then treated at 50vol% hydrogen / Ar balanced atmosphere at 80°C for 10min to obtain the precious metal The average particle size of the particles is 1.8nm, and the particle size distribution range is less than or equal to 3.7nm, of which single atomic dispersion accounts for 13% (calculated based on the infrared CO adsorption peak fitting results). Then, 80wt% 1-hexene / cyclohexane equilibrium solution is refluxed at 150°C for 120min to obtain Ir1@S-1 catalyst with single atomic dispersion accounting for 82% (calculated based on the infrared CO adsorption peak fitting results), wherein the particle size of the remaining precious metal Ir particles is greater than 2.5nm and less than or equal to 3.7nm.

[0039] Comparative Example 1: The noble metal is loaded by the impregnation method. 0.01g of platinum acetylacetonate is dissolved in 10g of ethanol, and 1g of silicon oxide powder is added. The powder is sieved through 100 mesh and has a diameter of less than 0.15mm. The powder is stirred for 6h, filtered and washed, and placed in an oven at 80°C for 12h to dry. A Pt / SiO2 catalyst precursor with a Pt loading of 0.5wt% of the whole is obtained. The precursor is then placed in a quartz tube and treated at 400°C for 20min in an 80vol% hydrogen / Ar equilibrium atmosphere to obtain a loaded Pt / SiO2 catalyst with an average particle size of 2.6nm and a particle size distribution range of less than or equal to 4.2nm, wherein the single-atom dispersion accounts for 6% (calculated based on the infrared CO adsorption peak split fitting results). Then, an 80vol% ethylene / He equilibrium atmosphere is used at 120°C for 30min to obtain a Pt / SiO2 catalyst with a single-atom dispersion of only 19% (calculated based on the infrared CO adsorption peak split fitting results). (As Figure 4 Most of the Pt shown is in the form of particles, the average particle size of the precious metal particles is 3.2nm, the particle size distribution is greater than 2.5nm and less than or equal to 4.1nm, and the single atomic dispersion accounts for only 19%)

[0040] Comparative Example 2: Ru / Al2O3 regeneration treatment. The catalyst in Example 4 was used for the selective hydrogenation reaction of nitrobenzene to obtain a used Ru / Al2O3 catalyst, wherein the Ru loading was 0.9wt%, and the Ru metal was partially agglomerated to form particles with an average particle size of 0.8nm and a particle size distribution of less than or equal to 1.3nm. The particles were calcined at 400°C in a 30vol% O2 / He balanced atmosphere for 120min to remove carbon deposits, and then treated at 400°C in a 50vol% hydrogen / He balanced atmosphere for 60min to obtain a catalyst Ru / Al2O3 with an average particle size of 3.4nm and a particle size distribution range of less than or equal to 6.2nm, wherein the single-atom dispersion accounted for less than 1% (calculated based on the infrared CO adsorption peak split fitting results). The catalyst was then treated at 150°C in a 60vol% butene / He balanced atmosphere for 120min to obtain a Ru / Al2O3 catalyst with a single-atom dispersion of only 2% (calculated based on the infrared CO adsorption peak split fitting results). (As Figure 5 As shown, most of the Ru exists in the form of particles. The average particle size of the precious metal particles is 3.6nm, and the particle size distribution is greater than 2.6nm and less than or equal to 6.4nm. There is an obvious agglomeration trend, and the single atomic dispersion accounts for only 2%)

[0041] Results Analysis

[0042] Figure 1 , 2 shows that this method can be used to prepare highly dispersed single-atom catalysts, and the precious metals exist in the form of single atoms.

[0043] Figure 3 It is shown that this method can be used to regenerate a used catalyst into a single-atom catalyst. Although the individual atoms are close to each other, all active sites are still exposed, and the atomic utilization rate is still 100%, so it can be identified as a single-atom catalyst.

[0044] Figure 4 It shows that when the average particle size of the particles before olefin dispersion treatment is greater than 2.5 nm, it is impossible to prepare a single-atom catalyst in which most of the precious metals are dispersed in the form of single atoms by this method, the atomic utilization rate cannot reach 100%, and the precious metals mostly exist in the form of agglomerates.

[0045] Figure 5 It shows that when the average particle size of the particles before olefin regeneration treatment is greater than 2.5nm, it is impossible to regenerate a single-atom catalyst in which most of the precious metals are dispersed in the form of single atoms through this method, and the atomic utilization rate cannot reach 100%. Most of the precious metals exist in the form of agglomerates, and even obvious aggregation occurs.

Claims

1. A method for preparing or regenerating a supported noble metal single-atom catalyst using olefins, characterized in that: The active component noble metal in the catalyst is one or more of Rh, Ru, Pd, Pt, and Ir, and the carrier is one or more of CeO2, Al2O3, TiO2, MgO, SiO2, MFI molecular sieve, Fe2O3, mesoporous carbon material CMK-3, activated carbon, and triphenylphosphine resin; Olefins are used to disperse or regenerate precious metal clusters or particles with a diameter of 2 or more atoms and 2.5 nm or less (preferably 2.3 nm or less, more preferably 2 nm or less) loaded in the catalyst, so that they are dispersed or regenerated into precious metal single atoms to obtain supported precious metal single atoms.

2. The method according to claim 1, characterized in that The catalyst is a newly prepared catalyst or a regenerated catalyst, and the total loading amount of the noble metal in the catalyst is 10-0.01 wt% (preferably 5-0.01 wt%, more preferably 2-0.01 wt%).

3. The method according to claim 1 or 2, characterized in that In the process of preparing supported single-atom catalysts from olefins, firstly, noble metals are loaded on a carrier by impregnation, coprecipitation or in-situ synthesis; the catalyst after noble metal loading is passed through a hydrogen atmosphere with a volume fraction of 10-100 vol% (preferably 15-100 vol%, more preferably 20-100 vol%), in which the rest of the hydrogen atmosphere is a balance gas except hydrogen, and the balance gas is one or more of N2, Ar, and He, and is treated at 20-300°C (preferably 50-200°C, more preferably 80-150°C) for 1-120 min (preferably 2-90 min, more preferably 2-60 min) to obtain a supported catalyst after hydrogen treatment, in which noble metal clusters or particles with a diameter of greater than or equal to 2 atoms and less than or equal to 2.5 nm (preferably less than or equal to 2.3 nm, more preferably less than or equal to 2 nm) are present in the catalyst, and then the noble metal clusters or particles in the catalyst are dispersed using olefins.

4. The method according to claim 1 or 2, characterized in that: In the process of olefin regeneration supported single-atom catalyst, the deactivated supported noble metal catalyst is first calcined at 100-600°C (preferably 150-550°C, more preferably 200-550°C) in an atmosphere of air and / or 10-90vol% (preferably 15-85vol%, more preferably 20-80vol%) O2 / inert gas for 30-240min (preferably 40-210min, more preferably 60-180min) to remove carbon deposits formed during the catalytic process, wherein the inert gas is one or more of N2, He, and Ar, and then heated to 100vol% (preferably 150-550vol%) by a calcination reaction. , more preferably 20-100vol%), in which the rest of the hydrogen atmosphere is a balance gas except hydrogen, and the balance gas is one or more of N2, Ar, and He, and treated at 20-300°C (preferably 50-200°C, more preferably 80-150°C) for 1-120min (preferably 2-90min, more preferably 2-60min) to obtain a supported catalyst after hydrogen treatment, in which there are noble metal clusters or particles with a diameter of greater than or equal to 2 atoms to less than or equal to 2.5nm (preferably less than or equal to 2.3nm, more preferably less than or equal to 2nm), and finally the noble metal clusters or particles in the olefin dispersed catalyst are used.

5. The method according to any one of claims 3-4, characterized in that: The process of using noble metal clusters or particles in olefin dispersed catalysts in the method for preparing or regenerating supported single atom catalysts is as follows: The supported catalyst after hydrogen treatment is passed through an olefin atmosphere with a volume fraction of 10-100 vol% (preferably 15-100 vol%, more preferably 20-100 vol%), in which the rest of the olefin atmosphere is a balance gas except for the olefin, and the balance gas is one or more of N2, Ar, He, H2, and CH4; the gas is calcined at a temperature of 20-300° C. (preferably 20-250° C., more preferably 20-200° C.) for 10-180 min (preferably 10-150 min, more preferably 10-120 min) to obtain a supported catalyst; the olefin in the olefin atmosphere is one or more of ethylene, propylene, butene, and butadiene; Alternatively, the supported catalyst after hydrogen treatment is passed through an olefin solution with a mass concentration of 20-100wt% (preferably 30-100wt%, more preferably 50-100wt%), in which the rest of the olefin solution except the olefin is a balance liquid, and the balance liquid is one or more of cyclohexane, toluene, benzene, N,N-dimethylformamide, 1,4-dioxane, straight-chain alkane, tetrahydrofuran, dichloromethane, methanol, ethanol, acetone, acetonitrile, and isopropanol, and the solution is stirred at a temperature of 20-200° C. (preferably 20-180° C., more preferably 20-150° C.) for 10-180 min (preferably 10-150 min, more preferably 10-120 min) to obtain a supported catalyst; the olefin in the olefin liquid is C4-C 10 Monoolefins, C4-C 10 One or more of the dienes.

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