Method for preparing aluminum-based carrier and bimetal with reduction function using carbon-containing gas

Abstract

To provide a method for producing a bimetallic monoatomic catalyst which can be controlled by a simple, mild and efficient method so that a bimetal is uniformly and stably dispersed on the surface of a carrier in an atomic form.SOLUTION: To provide a method for producing a bimetallic monoatomic catalyst having the following steps. (1) heat-treating an aluminum-based material with a carbon-containing gas to form a reducing active material on the surface of an aluminum-based carrier; (2) An aluminum-based support having a reducing function is uniformly mixed with a bimetal precursor solution by an impregnation method, and the bimetal is controlled to be uniformly and stably dispersed on the surface of the support in an atomic form by a surface reducing substance. The surface of the aluminum-based carrier is modified with a carbon-containing gas to form a reducing substance on the surface, and in the impregnation process, the reducing substance acts on two kinds of metal ions at the same time, and then the substance is detached from the surface of the carrier to form pores, and the formed pores fix the pair of metals to form an atomic pair.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a method for preparing aluminum-based supports and bimetallic single-atom catalysts with reducing function using carbon-containing gases. [Background technology]

[0002] Single-atom catalyst Catalysts are widely used in industries such as chemical transformation, petroleum, energy, pharmaceuticals, and the environment, and play an important role in the domestic economy, the global environment, and human welfare. Heterogeneous catalysts, among others, have attracted widespread attention due to their advantages, such as easy functionalization, easy recovery, reusability, and simple preparation. However, heterogeneous catalysts used in industrial production are typically nanometal catalysts, and only a few metal nanoparticles with appropriate sizes or specific exposed crystal faces are recognized as catalytically active sites in reactions, resulting in low metal atom utilization and wasted resources. Single-atom catalysts further reduce the size of metal nanoparticles to the atomic level, forming uniform active sites and maximizing the utilization of catalytic active sites, thereby improving catalytic reactivity and metal atom utilization. However, single-metal catalysts have relatively simple structures and lack interatomic cooperation, making it difficult to simultaneously achieve high activity for different catalytic reactions simply by controlling the type of central metal atom, the atomic coordination structure, and the support structure. Due to the high surface energy of single-atom catalysts, aggregation of single atoms often occurs during activation or reaction, limiting their ability to exert greater catalytic activity.

[0003] Bimetallic single-atom catalysts overcome the structural monotony of single-atom catalysts. The diversity of adsorption and active sites on the catalyst leads to different electron transfer pathways, providing more possibilities for catalytic reactions and improving overall catalytic performance. Therefore, the construction of bimetallic single-atom catalysts with high synergistic effects has become a hot research topic in the field of catalysis. Chinese Patent CN114522682B describes the preparation of bimetallic nanoparticles supported on carbon supports by impregnating a carbon support with equal volumes of precursor solutions containing bimetals N and M, followed by inert gas sintering and high-temperature hydrogen reduction. The bimetallic single-atom catalysts were then prepared by reacting carbon monoxide and halogen-containing compounds with the bimetals and performing an in situ atomic-level dispersed heat treatment reaction. Chinese Patent CN112023934B describes the synthesis of bimetallic precursor powder Cu / In@ZIF-8 using a one-pot method, followed by high-temperature pyrolysis under inert gas protection to obtain copper-indium bimetallic single-atom catalysts. Hu Wenbin et al. reported a study on dual Pt-Ni atom dispersion on N-doped carbon nanostructures with novel (NiPt)-NC configurations for synergistic electrocatalytic hydrogen evolution reaction [J]. Science China Materials, 2023, 66(4):1389-1397. They prepared Ni-NC as a nitrogen-doped carbon substrate by high-temperature pyrolysis, then deposited Pt on the NC and Ni-NC samples using atomic layer deposition (ALD) to obtain Pt / Ni-NC bimetallic single-atom catalysts. These methods all involve high-temperature heat treatments, which tend to cause metal atom aggregation. It is difficult to precisely control the uniform and stable dispersion of the bimetal on the support at atomic size. Furthermore, these methods are complex and expensive, limiting the catalytic activity and further applications of bimetallic single-atom catalysts.

[0004] To solve the problems inherent in the above-mentioned preparation methods for bimetallic single-atom catalysts, existing manufacturing techniques need to be improved. The support material is one of the most important factors affecting the performance of supported metal catalysts, and is crucial for adjusting particle size and shape, chemical composition, exposure of active sites, and the formation of synergistic interactions at the metal-support interface. Widely used aluminum-based supports, such as alumina in various crystalline phases, alumina doped with other oxides, molecular sieves, and aluminum-containing hydrotalcites, have special advantages, such as easily controllable surface properties, tunable microstructures, abundant reserves, low cost, and simple industrial preparation processes. However, metal loading on aluminum-based supports typically involves sintering at high temperatures or reducing metal precursors under the action of reducing agents. However, these methods tend to result in the active components agglomerating to form particles, resulting in insufficient catalytic activity. Therefore, it is necessary to modify the surface of aluminum-based supports, design aluminum-based supports with surface reduction functions, and control the uniform and stable dispersion of bimetals on the support surface in atomic form in a simple, mild, and efficient manner. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing a highly dispersed bimetallic single atom catalyst by heat treating an aluminum-based material with a carbon-containing gas to prepare an aluminum-based support having a reducing function and then using the aluminum-based support to support a bimetal.

[0006] The method for preparing an aluminum-based support having a reducing function using a carbon-containing gas provided by the present invention is characterized in that it involves treating an aluminum-based material with a carbon-containing gas to form a reducing substance on its surface, and then impregnating the aluminum-based material with a bimetal by impregnation, whereby the reducing substance can simultaneously react with two types of metal ions, and then the reducing substance desorbs from the support surface to form vacancies, which then fix the pair of metals to form atomic pairs, allowing the bimetal to be uniformly and stably dispersed on the support surface in atomic form. The specific steps are as follows:

[0007] Step A: The aluminum-based material is placed in a tubular furnace and sealed. The balance gas is introduced into the furnace through a deoxidizer, and the furnace is checked for airtightness. The reaction gas is then introduced into the furnace through a deoxidizer containing 20-80g of manganese-based deoxidizer. After 10-30 minutes of reaction gas introduction, the reactor is heated using a programmed temperature ramp. After the reaction is complete, the reactor is cooled to room temperature. The resulting reduced aluminum-based support is quickly removed and stored in a sealed vacuum bag.

[0008] The aluminum-based material is one of pseudo-boehmite, lanthanum-doped pseudo-boehmite, silicon-doped pseudo-boehmite, phosphorus-doped pseudo-boehmite, aluminum hydroxide, ZSM5-molecular sieve, and MgAl-LDHs, and preferably pseudo-boehmite and aluminum hydroxide.

[0009] The reaction gas is a uniform mixture of a carbon-containing gas and a balance gas at a predetermined volume ratio. The carbon-containing gas is at least one selected from CH4, C2H6, C2H4, C2H2, CO, CH3Cl, CH2Cl2, CHCl3, and CCl4, and preferably, the carbon-containing gas is one or more of CH4, C2H6, C2H4, C2H2, and CO. The volume content of the carbon-containing gas in the reaction gas is 1%-80%, and the remainder is a balance gas, and preferably, the volume content of the carbon-containing gas is 1%-60%. The balance gas is nitrogen gas.

[0010] The deoxidizer is a drying tube containing a manganese-based deoxidizer, which is a manganese-based metal oxide and is used to remove oxygen and purify nitrogen gas and carbon-containing gas.

[0011] The conditions for heating the reactor by the programmed temperature increase are a gas flow rate of 1 mL / min-100 mL / min, preferably 20 mL / min-80 mL / min, a temperature increase rate of 1-100°C / min, preferably 5-10°C / min, a reaction temperature of 200-1000°C, preferably 400-800°C, and a reaction time of 0.5-10 hours, preferably 2-6 hours.

[0012] Step B: Dissolve the soluble metal M salt and soluble metal Pd salt in deionized water and sonicate for 5-10 minutes to fully dissolve them, obtaining a bimetallic precursor solution containing M and Pd. The aluminum support obtained in Step A is used as the support, and the bimetallic precursor solution containing M and Pd is added as the immersion solution. The immersion solution is heated to 40-90°C in a water bath, and a magnetic stirrer is added, stirring at 300-1000 rpm. After the water in the solution evaporates, the evaporated, solidified sample is placed in an oven at 40-90°C and dried for 4-24 hours to obtain the bimetallic single-atom catalyst.

[0013] The soluble metal M salt is one of HAuCl4, NaAuCl4, RuCl3, RuCl3·3H2O, HPtCl4, HPtCl6, K2PtCl4, K2PtCl6, Pt(NO3)2, [Pt(NH3)4]Cl2, Rh(CH3COO)3, Rh(NO3)3, H2IrCl6, and Na2IrCl6, preferably one of HAuCl4, RuCl3, and HPtCl6. The soluble metal Pd salt is one of Na2PdCl4, Pd(NH3)2Cl2, Pd(NO3)2, and Pd(CH3COO)2, preferably Na2PdCl4.

[0014] The mass content of metal M and metal Pd supported on the bimetallic single-atom catalyst is 0.01%-20%, preferably 0.01%-10%, and the mass ratio of metal M to metal Pd supported on the bimetallic single-atom catalyst is 0.1-20%, preferably 0.1-10.

[0015] The bimetallic single-atom catalyst is expressed as xMyPd / ZT, where M and Pd represent active components, M is any one of Au, Ru, Rh, Pt, and Ir, preferably any one of Au, Ru, and Pt, x and y represent the mass content of each component in the prepared bimetallic single-atom catalyst, and ZT represents the aluminum-based support.

[0016] The resulting aluminum-based support and bimetallic single atom catalyst were characterized as follows:

[0017] 1(a) and (b) are the XRD patterns of the alumina supports prepared in Examples 1 and 2, respectively, which demonstrate that γ-alumina was prepared by this method.

[0018] Figure 2(1), (2), and (3) show the low-temperature nitrogen gas adsorption / desorption curves (a) and pore size distributions (b) of the alumina supports prepared in Examples 1, 2, and 3, respectively. As can be seen from Figure 2(a), the adsorption isotherms of the samples prepared by this method are type IV, indicating that the catalysts have a good mesoporous structure. The hysteresis patterns are type H3, indicating that the alumina supports prepared in Examples 1, 2, and 3 all have a mesoporous structure and the pores are "wedge-shaped pores" formed by the deposition of flaky particles. As can be seen from Figure 2(b), the pore sizes of the alumina supports prepared by this method range from 2 to 72 nm, with mode diameters of approximately 3.8 nm and 9.3 nm, respectively.

[0019] Figures 3(1) and 3(2) show the low-temperature nitrogen gas adsorption / desorption curves (a) and pore size distributions (b) of the ZSM5-molecular sieve and MgAl-LDOs supports prepared in Examples 4 and 5, respectively. As can be seen from Figure 3(a), the adsorption isotherms of the samples prepared by this method are type IV, indicating that the catalysts have a good mesoporous structure. The hysteresis patterns are type H2, indicating that both the ZSM5-molecular sieve and MgAl-LDOs supports prepared in Examples 4 and 5 have an "ink bottle" mesoporous structure. As can be seen from Figure 3(b), the pore sizes of the ZSM5-molecular sieve and MgAl-LDOs supports prepared in Examples 4 and 5 are both 2-57 nm, with a mode diameter of approximately 7.5 nm.

[0020] Figure 4 shows a TEM image and EDS-mapping diagram of the 0.5%Pt1.0%Pd / Al2O3 prepared in Example 2. This figure shows that the two metals, Pd and Pt, are uniformly and highly dispersed on the support, since no agglomerated metal particles are observed on the support surface.

[0021] Figure 5 (a), (b), (c), and (d) are TEM images of the bimetallic single-atom catalysts prepared in Examples 2, 3, 4, and 5, respectively. No particles are observed in any of the images, indicating that the supported bimetals are all highly dispersed in the form of single atoms after treatment with carbon-containing gases in aluminum-based materials such as aluminum hydroxide, pseudoboehmite, ZSM-5 molecular sieve, and aluminum-containing hydrotalcite MgAl-LDH.

[0022] Figure 6 shows the HAADF-STEM image of the 1.0%Ru0.5%Pd / ZSM5-molecular sieve prepared in Example 4. This image shows that the two metals, Pd and Ru, are distributed in the ZSM5-molecular sieve support in the form of diatomic pairs.

[0023] Figure 7 shows the XRD patterns of the 0.5%Au0.5%Pd / Al2O3 prepared in Example 1, the 0.5%Au / Al2O3 prepared in Comparative Example 1, and the 0.5%Pd / Al2O3 prepared in Comparative Example 2. As can be seen from this figure, γ-alumina was successfully prepared by all of these methods, and no diffraction peaks characteristic of metal particles were observed in any of the three types of catalysts, indicating that the metal particles supported on these catalysts were uniformly dispersed.

[0024] Figure 8 shows XPS charts (a) and (b) for Au 4f in the 0.5%Au0.5%Pd / Al2O3 catalyst prepared in Example 1 and Comparative Example 1, respectively, and Pd 3d in the 0.5%Au0.5%Pd / Al2O3 catalyst prepared in Example 1 and Comparative Example 2, respectively. Based on the bond energy positions, it is estimated that the valence of Au in the 0.5%Au0.5%Pd / Al2O3 catalyst is slightly lower than that in the 0.5%Au / Al2O3 catalyst, while the valence of Pd in ​​the 0.5%Au0.5%Pd / Al2O3 catalyst is slightly higher than that in the 0.5%Pd / Al2O3 catalyst. This indicates that there is an interaction between the Au and Pd atoms in such bimetallic catalysts, and that the bimetal exists in the form of atomic pairs. The beneficial effects of the present invention are as follows:

[0025] In the present invention, a special reducing substance is present on the surface of an aluminum-based support obtained by heat-treating an aluminum-based material with a carbon-containing gas. By supporting a bimetal on such an aluminum-based support with a reducing substance on its surface, two metal ions can be directly reduced in situ during the impregnation process, achieving simultaneous metal ion loading and reduction, with the two metals ultimately dispersed in the support in the form of atomic pairs. Compared with the conventional impregnation method using high-temperature hydrogen reduction, the method of the present invention is simpler and operates under milder conditions, thereby avoiding the deactivation of metal catalytic active components caused by the aggregation of metal atoms during high-temperature reduction in the conventional impregnation method. [Brief explanation of the drawings]

[0026] [Figure 1] 1(a) and (b) are the XRD patterns of the alumina supports prepared in Examples 1 and 2, respectively. [Figure 2] Figure 2 (1), (2), and (3) show (a) the low-temperature nitrogen gas adsorption / desorption curves and (b) the pore size distribution diagrams of the alumina supports prepared in Examples 1, 2, and 3, respectively. [Figure 3] 3(1) and (2) are the low-temperature nitrogen gas adsorption / desorption curves (a) and pore size distribution diagrams (b) of the ZSM5-molecular sieve carrier and the MgAl-LDOs carrier prepared in Examples 4 and 5, respectively. [Figure 4] TEM and EDS-mapping diagrams of 0.5%Pt1.0%Pd / Al2O3 prepared in Example 2. [Figure 5] Figure 5 (a), (b), (c), and (d) are TEM images of the bimetallic single-atom catalysts prepared in Examples 2, 3, 4, and 5, respectively. [Figure 6] FIG. 1 is a HAADF-STEM image of the 1.0%Ru0.5%Pd / ZSM5 molecular sieve prepared in Example 4. [Figure 7] 1 shows XRD patterns of 0.5%Au0.5%Pd / Al2O3 prepared in Example 1, 0.5%Au / Al2O3 prepared in Comparative Example 1, and 0.5%Pd / Al2O3 prepared in Comparative Example 2. [Figure 8] 1A is an XPS chart of Au 4f in 0.5%Au0.5%Pd / Al2O3 prepared in Example 1 and 0.5%Au / Al2O3 prepared in Comparative Example 1, and FIG. 1B is an XPS chart of Pd 3d in 0.5%Au0.5%Pd / Al2O3 prepared in Example 1 and 0.5%Pd / Al2O3 prepared in Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0027] In the following examples, the gas content is a volume content.

[0028] Example 1 Step A: 4,0000 g of pseudoboehmite was weighed and placed in a porcelain boat, which was then sealed in a tubular furnace. Nitrogen gas was introduced into the tubular furnace through a deoxidizer containing 30 g of manganese-based deoxidizer, and the furnace was airtight. The reaction gas was then passed through the deoxidizer and introduced into the tubular furnace over 15 min. A 20% CH4 / 80% N2 (balance gas) mixture was selected as the reaction gas, and the reaction was heat-treated at 500 °C. The heating rate was 5 °C / min, the gas flow rate was 80 mL / min, and the reaction time was 6 h. After the reaction, the sample was cooled to room temperature in the reaction atmosphere and removed to obtain a reducing alumina support, which was then sealed and stored in a vacuum-sealed bag. Step B: 0.0173 g of NaAuCl4 and 0.0276 g of Na2PdCl4 were dissolved in 15 mL of deionized water and sonicated for 6 min to fully dissolve the solution, preparing a NaAuCl4-Na2PdCl4 bimetallic precursor solution. 2.0000 g of the alumina support obtained in Step A was placed in a 100 mL beaker, and the bimetallic precursor solution was added. The mixture was heated in an 80 °C water bath with a stirring speed of 500 rpm. After the water in the solution evaporated, the evaporated, solidified sample was placed in an oven at 80 °C and dried. The mass percentages of Au and Pd in ​​the resulting catalyst were both 0.5%, expressed as 0.5%Au0.5%Pd / Al2O3.

[0029] Example 2 Step A: 4,0000 g of aluminum hydroxide was weighed and placed in a porcelain boat, which was then sealed in a tubular furnace. Nitrogen gas was introduced into the tubular furnace through a deoxidizer containing 30 g of manganese-based deoxidizer, and the furnace was sealed to ensure airtightness. The reaction gas was then passed through the deoxidizer and introduced into the tubular furnace over 15 min. The reaction gas was a mixture of 5% CH, 5% CH, and 90% N (balance gas), and the reaction was performed at 600 °C. The heating rate was 10 °C / min, the gas flow rate was 80 mL / min, and the reaction time was 6 h. After the reaction, the sample was cooled to room temperature in the reaction atmosphere and removed to obtain a reducing alumina support, which was then sealed and stored in a vacuum-sealed bag. Step B: 0.0210 g of HPtCl6 and 0.0552 g of NaPdCl4 were dissolved in 15 mL of deionized water and sonicated for 6 min to fully dissolve the mixture, preparing a HPtCl6-NaPdCl4 bimetallic precursor solution. 2.0000 g of the alumina support obtained in Step A was placed in a 100 mL beaker, and the bimetallic precursor solution was added. The mixture was heated in a water bath at 70 °C with a stirring speed of 500 rpm. After the water in the solution evaporated, the evaporated, solidified sample was placed in an oven at 70 °C and dried. The mass percentages of Pt and Pd in ​​the resulting catalyst were both 0.5%, expressed as 0.5% Pt / 1.0% Pd / Al2O3.

[0030] Example 3 Step A: 4,0000 g of pseudoboehmite was weighed and placed in a porcelain boat, which was then sealed in a tubular furnace. The boat was passed through a deoxidizer containing 30 g of manganese-based deoxidizer and introduced into the tubular furnace. The airtightness of the furnace was confirmed. The reaction gas was then passed through the deoxidizer and nitrogen gas was introduced into the tubular furnace for 15 min. A 40% CO / 60% N2 (balance gas) mixture was selected as the reaction gas, and the sample was heat-treated at 500 °C. The heating rate was 5 °C / min, the gas flow rate was 60 mL / min, and the reaction time was 4 h. After the reaction, the sample was cooled to room temperature in the reaction atmosphere and removed to obtain a reducing alumina support, which was then sealed and stored in a vacuum-sealed bag. Step B: 0.0205 g of RuCl3 and 0.0276 g of Na2PdCl4 were dissolved in 15 mL of deionized water and sonicated for 6 min to fully dissolve the mixture, preparing a RuCl3-Na2PdCl4 bimetallic precursor solution. 2.0000 g of the alumina support obtained in Step A was placed in a 100 mL beaker, and the bimetallic precursor solution was added. The mixture was heated in a water bath at 70 °C with a stirring speed of 500 rpm. After the water in the solution evaporated, the evaporated, solidified sample was placed in an oven at 70 °C and dried. The mass percentages of Ru and Pd in ​​the resulting catalyst were both 0.5%, expressed as 0.5%Ru0.5%Pd / Al2O3.

[0031] Example 4 Step A: 4,0000 g of ZSM-5 molecular sieve was weighed and placed in a porcelain boat, which was then sealed in a tubular furnace. The boat was passed through a deoxidizer containing 30 g of manganese-based deoxidizer and introduced into the tubular furnace. The airtightness of the furnace was confirmed. The reaction gas was then passed through the deoxidizer and introduced into the tubular furnace for 15 min. A 20% CH4 / 80% N2 (balance gas) mixture was selected as the reaction gas and heat-treated at 800 °C. The heating rate was 10 °C / min, the gas flow rate was 50 mL / min, and the reaction time was 4 h. After the reaction, the sample was cooled to room temperature in the reaction atmosphere and removed to obtain a reducing ZSM-5 molecular sieve support, which was then sealed and stored in a vacuum-sealed bag. Step B: 0.0410 g of RuCl3 and 0.0276 g of Na2PdCl4 were dissolved in 15 mL of deionized water and sonicated for 6 min to fully dissolve the mixture, preparing a RuCl3-Na2PdCl4 bimetallic precursor solution. 2.0000 g of the ZSM-5 molecular sieve support obtained in Step A was placed in a 100 mL beaker, and the bimetallic precursor solution was added. The mixture was heated in a water bath at 70 °C with a stirring speed of 500 rpm. After the water in the solution evaporated, the evaporated, solidified sample was placed in an oven at 70 °C and dried. The mass percentages of Ru and Pd in ​​the resulting catalyst were both 0.5%, expressed as 1.0% Ru 0.5% Pd / ZSM5-molecular sieve.

[0032] Example 5 Step A: MgAl-LDHs support was prepared by coprecipitation. 11.8631 g of Mg(NO3)2 and 8.5202 g of Al(NO3) were dissolved in 100 mL of deionized water to obtain solution A, and 0.6000 g of NaOH and 3.1800 g of Na2CO3 were dissolved in 100 mL of deionized water to obtain solution B. Solutions A and B were added dropwise to a reactor containing 100 mL of deionized water, and the pH of the system was controlled at 9.6 ± 0.05. The reactor was then heated to 70 °C and maintained for 8 h. After completion, the reactor was centrifuged, washed until the pH of the supernatant reached 7.0, and then dried to obtain MgAl-LDHs. 4.000 g of MgAl-LDHs was weighed and placed in a porcelain boat, which was then sealed in a tube furnace. Nitrogen gas was introduced into the tubular furnace through a deoxidizer containing 30 g of manganese-based deoxidizer, and the airtightness of the furnace was confirmed. The reaction gas was then passed through the deoxidizer and introduced into the tubular furnace over 15 min. A 25% CH / 75% N mixture (balance gas) was selected as the reaction gas, and the sample was heat-treated at 800 °C. The heating rate was 5 °C / min, the gas flow rate was 60 mL / min, and the reaction time was 4 h. After the reaction, the sample was cooled to room temperature in the reaction atmosphere and removed. The resulting MgAl-LDOs support was obtained and stored in a sealed vacuum bag. Step B: 0.0173 g of NaAuCl4 and 0.0276 g of Na2PdCl4 were dissolved in 15 mL of deionized water and sonicated for 6 min to prepare a NaAuCl4-Na2PdCl4 bimetallic precursor solution. 2.0000 g of the MgAl-LDOs support obtained in Step A was placed in a 100 mL beaker, and the prepared NaAuCl4-Na2PdCl4 bimetallic precursor solution was added. The mixture was heated in a water bath at 80 °C with a stirring speed of 500 rpm. After the water in the solution evaporated, the evaporated sample was placed in an oven at 80 °C and dried. The mass percentages of Au and Pd in ​​the resulting catalyst were both 0.5%, expressed as 0.5% Au 0.5% Pd / MgAl-LDOs.

[0033] Comparative Example 1 An alumina support of 0.5% Au / Al2O3 was prepared in the same manner as in Example 1. Step A: 4,0000 g of pseudoboehmite was weighed and placed in a porcelain boat, which was then sealed in a tubular furnace. Nitrogen gas was introduced into the tubular furnace through a deoxidizer containing 30 g of manganese-based deoxidizer, and the furnace was airtight. The reaction gas was then passed through the deoxidizer and introduced into the tubular furnace over 15 min. A 20% CH4 / 80% N2 (balance gas) mixture was used as the reaction gas, and the reaction was heat-treated at 500 °C. The heating rate was 5 °C / min, the gas flow rate was 80 mL / min, and the reaction time was 6 h. After the reaction, the sample was cooled to room temperature in the reaction atmosphere and removed to obtain a reducing alumina support, which was then sealed and stored in a vacuum-sealed bag. Step B: 0.0173 g of NaAuCl4 was dissolved in 15 mL of deionized water and sonicated for 6 minutes to fully dissolve the solution, preparing a NaAuCl4 metal precursor solution. 2.0000 g of the alumina support obtained in Step A was placed in a 100 mL beaker, and the prepared NaAuCl4 metal precursor solution was added. The mixture was heated in an 80 °C water bath with a stirring speed of 500 rpm. After the water in the solution evaporated, the evaporated and solidified sample was placed in an oven at 80 °C and dried. The mass % of Au in the resulting catalyst was 0.5%, expressed as 0.5%Au / Al2O3.

[0034] Comparative Example 2 An alumina support of 0.5% Pd / Al2O3 was prepared in the same manner as in Example 1. Step A: 4,0000 g of pseudoboehmite was weighed and placed in a porcelain boat, which was then sealed in a tubular furnace. Nitrogen gas was introduced into the tubular furnace through a deoxidizer containing 30 g of manganese-based deoxidizer, and the furnace was airtight. The reaction gas was then passed through the deoxidizer and introduced into the tubular furnace over 15 min. A 20% CH4 / 80% N2 (balance gas) mixture was used as the reaction gas, and the reaction was heat-treated at 500 °C. The heating rate was 5 °C / min, the gas flow rate was 80 mL / min, and the reaction time was 6 h. After the reaction, the sample was cooled to room temperature in the reaction atmosphere and removed to obtain a reducing alumina support, which was then sealed and stored in a vacuum-sealed bag. Step B: 0.0276 g of Na2PdCl4 was dissolved in 15 mL of deionized water and sonicated for 6 minutes to fully dissolve the solution, preparing a Na2PdCl4 metal precursor solution. 2.0000 g of the alumina support obtained in Step A was placed in a 100 mL beaker, and the prepared Na2PdCl4 metal precursor solution was added. The mixture was heated in an 80 °C water bath with a stirring speed of 500 rpm. After the water in the solution evaporated, the evaporated and dried sample was placed in an oven at 80 °C and dried. The mass% of Pd in ​​the resulting catalyst was 0.5%, expressed as 0.5%Pd / Al2O3.

Claims

1. A method for preparing an aluminum-based support and a bimetallic single-atom catalyst having a reducing function using a carbon-containing gas, comprising the steps of: The method includes the following steps A and B: Step A: The aluminum-based material is placed in a tubular furnace and sealed. A balance gas is introduced into the tubular furnace through a deoxidizer. The airtightness of the furnace is confirmed. Then, a reaction gas is introduced into the tubular furnace through a deoxidizer. 10-30 minutes after the reaction gas is introduced, the reactor is heated by a programmed temperature increase. After the reaction is completed, the reactor is cooled to room temperature. The reduced aluminum-based support obtained after the treatment is quickly removed and stored in a sealed vacuum packaging bag. the aluminum-based material is one of pseudoboehmite, lanthanum-doped pseudoboehmite, silicon-doped pseudoboehmite, phosphorus-doped pseudoboehmite, aluminum hydroxide, ZSM5-molecular sieve, and MgAl-LDHs; The reaction gas is a uniform mixture of a carbon-containing gas and a balance gas, and the carbon-containing gas is CH ４ , C ２ H ６ , C ２ H ４ , C ２ H ２ , CO, CH ３ Cl, CH ２ Cl ２ , CHCl ３ , CCl ４ At least one selected from The volume content of the carbon-containing gas in the reaction gas is 1%-80%, and the remainder is a balance gas, the balance gas being nitrogen gas; The conditions for heating the reactor by the programmed temperature rise are a gas flow rate of 1 mL / min to 100 mL / min, a temperature rise rate of 1 to 100°C / min, a reaction temperature of 200 to 1000°C, and a reaction time of 0.5 to 10 hours. Step B: Dissolve the soluble metal M salt and soluble metal Pd salt in deionized water, and thoroughly dissolve them by ultrasonic treatment for 5-10 minutes to obtain a bimetallic precursor solution containing M and Pd. The aluminum support obtained in step A is used as the support, and the bimetallic precursor solution containing M and Pd is added as an immersion solution. Under water bath conditions at 40-90°C, the immersion solution is added, and a magnetic stirrer is added and stirred at a rotation speed of 300-1000 rpm. After the water in the solution evaporates, the evaporated and solidified sample is placed in an oven at 40-90°C and dried for 4-24 hours to obtain a bimetallic single-atom catalyst. In step B, the soluble metal M salt is HAuCl ４ , NaAuCl ４ , RuCl ３ , RuCl ３ ・3H ２ O, H ２ PtCl ４ , H ２ PtCl ６ , K. ２ PtCl ４ , K. ２ PtCl ６ , Pt(NO ３ ) ２ [Pt(NH ３ ) ４ ]Cl ２ , Rh(CH ３ COO) ３ , Rh(NO ３ ) ３ , H ２ IrCl ６ and Na ２ IrCl ６ and the soluble metal Pd salt is one of Na ２ PdCl ４ , Pd(NH ３ ) ２ Cl ２ , Pd(NO ３ ) ２ , Pd(CH ３ COO) ２ It is one of the The metal M and metal Pd supported on the obtained bimetallic single-atom catalyst each have a mass content of 0.01%-20% in the catalyst, and the mass ratio of the metal M to the metal Pd supported on the bimetallic single-atom catalyst in the catalyst is 0.1-20.

2. 2. The method of claim 1, wherein in step A, the deoxidizer is a drying tube doped with a 401 manganese-based deoxidizer.

3. The method of claim 1, characterized in that the prepared bimetallic single-atom catalyst is represented by xMyPd / ZT, where M and Pd represent active components, M is any one of Au, Ru, Rh, Pt, and Ir, x and y represent the mass contents of metal M and metal Pd in ​​the catalyst, respectively, where x and y are both 0.01%-20%, and ZT represents the aluminum-based support obtained by treating with a carbon-containing gas.

4. The carbon-containing gas is CH ４ , C ２ H ６ , C ２ H ４ , C ２ H ２ 2. The method of claim 1, wherein the carbon monoxide is any one or more of:

5. 2. The method according to claim 1, wherein the apparatus used in the method comprises two or three gas cylinders, one for balance gas and one or two for carbon-containing gas, the volume content of the carbon-containing gas in the reaction gas entering the tubular furnace being 1%-60%, and the rest being nitrogen gas.

6. 2. The method according to claim 1, wherein the apparatus used in the method comprises a carbon-containing gas cylinder, a balance gas cylinder, a deoxygenation device, a reactor, and an exhaust gas collecting bottle, wherein the carbon-containing gas cylinder and the balance gas cylinder are respectively connected to the deoxygenation device via mass flow meters, the deoxygenation device is connected to the reactor via an air passage, pressure gauges are provided at the inlet and outlet of the reactor, and an exhaust gas collecting bottle is provided after the reactor.

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