A platinum-ruthenium bimetallic catalyst, its preparation method and use

Abstract

The application discloses a platinum-ruthenium bimetallic catalyst and a preparation method thereof, and application of the platinum-ruthenium bimetallic catalyst in catalyzing CO2 hydrogenation to synthesize multi-carbon compounds. The platinum-ruthenium bimetallic catalyst of the application is basically composed of platinum nanoparticles loaded on a carrier, and the surface of the platinum nanoparticles is embedded with ruthenium atoms and / or ruthenium clusters. The ratio of platinum / ruthenium atoms in the catalyst is 1:2-100:1, and the particle size of the platinum nanoparticles, whose surface is embedded with ruthenium atoms and / or ruthenium clusters, is 1-5 nanometers. The application further discloses a synthesis method of the above catalyst, and the method is characterized in that Pt nanoparticle-assisted dispersion of Ru atoms in Ru nanoparticles into a single metal atom complex is an important feature. The novel platinum-ruthenium bimetallic catalyst of the application exhibits outstanding C 2+ selectivity in catalyzing CO2 hydrogenation to synthesize multi-carbon hydrocarbons and multi-carbon alcohols.

Description

Technical Field

[0001] This invention relates to a platinum nanoparticle catalyst with ruthenium atoms and / or ruthenium clusters embedded on its surface, a method for synthesizing the catalyst, and its application in catalyzing the hydrogenation of carbon dioxide to synthesize multicarbon compounds. Background Technology

[0002] Platinum-ruthenium (PtRu) bimetallic catalysts exhibit superior performance to monometallic catalysts in many catalytic reactions due to their different atomic arrangement and electronic structure compared to corresponding monometallic catalysts. As anode catalysts in fuel cells or hydrogenation reactions, the use of bimetallic catalysts can effectively reduce the poisoning effect of CO in the feed gas or improve the selectivity of the target product. The properties of PtRu bimetallic catalysts depend on their atomic arrangement and their role on the support. Previous supported PtRu bimetallic catalysts have solid solution alloy structures or core-shell structures (XXYuan et al., J. Electrochem. Soc., 2017, 164, F1641-F1647; V.Birss et al., ACS Appl.Energ. Mater., 2020, 3, 8423-8436). PtRu bimetallic solid solution nanocatalysts can be prepared by co-reduction of two metal salts or complexes followed by alloying. Core-shell structured PtRu metal catalysts are typically formed by reducing one metal salt on the surface of one metal nanoparticle and generating it on its surface. Since the thermodynamically stable structure of the Pt-Ru bimetallic system is a solid solution alloy structure, it will usually form a solid solution alloy structure at high preparation temperatures.

[0003] On the other hand, excessive CO2 emissions have led to severe greenhouse effects and other problems, significantly limiting the sustainable development of human society. Meanwhile, enormous energy demands are increasing dependence on finite fossil fuels. Converting CO2 into high-value-added products (fuels or chemical feedstocks) through catalytic hydrogenation can not only reduce dependence on fossil resources such as oil but also effectively reduce CO2 emissions, mitigating environmental problems such as the greenhouse effect and ocean acidification. Among various CO2 conversion pathways, catalytic conversion of CO2 into high-value-added products at low temperatures or ambient temperatures (<150℃) will bring greater environmental and economic benefits. The development of technologies such as solar power generation and electrolytic hydrogen production has made large-scale hydrogen production possible in an environmentally friendly manner, and the catalytic hydrogenation of CO2 into high-value-added products at low temperatures shows broad development prospects.

[0004] Catalytic conversion of CO2 to organic compounds, especially multi-carbon compounds, using previously reported catalysts typically requires high temperatures. Li et al. prepared a Cu-Zn-Fe composite catalyst using a co-precipitation method and modified it with K (K / Cu-Zn-Fe). The resulting catalyst could catalyze the hydrogenation of CO2 to organic compounds at 573 K, with a mass selectivity of 36.67% for multi-carbon alcohols in the product (SGLi et al., Catal. Lett., 2013, 143, 345-355). Han et al. prepared Co3O4-supported Pt nanoparticles that could catalyze the hydrogenation of CO2 to organic compounds under mild conditions of 413 K, with C2-C4 multi-carbon alcohols accounting for 35.2% of the alcohols (C1-C4) (BXHan et al., Angew. Chem. Int. Ed., 2016, 55, 737-741). Sun et al. reported that the Na-Fe3O4 / HZSM-5 catalyst can catalyze the hydrogenation of CO2 to organic compounds at 593 K, with the product containing C5-C64. 11 The selectivity for hydrocarbon compounds reached 78%. The bifunctional catalyst In₂O₃ / HZSM-5 prepared by Zhong et al. can catalyze the conversion of CO₂ to organic compounds. At a reaction temperature of 613 K, the CO₂ conversion rate was 13.1%, and the selectivity for multi-carbon hydrocarbons in the gasoline component of the product reached 78.6% (J.Sun et al., Nat. Commun., 2017, 8, 15174.; P.Gao et al., Nat. Chem., 2017, 9, 1019-1024.). The bifunctional catalyst composed of ZnO-ZrO₂ solid solution and SAPO-34 molecular sieve reported by Li et al. can effectively catalyze the reaction of CO₂ and H₂ to organic compounds under reaction conditions of 653 K and 2 MPa, in which low-carbon olefins (C₂-C₄) account for up to 80% of the hydrocarbons (C.Li et al. ACS Catal., 2017, 7, 8544-8548.).

[0005] Regarding high selectivity at low temperatures (C 2+ Selectivity >80% catalytically catalyzes the hydrogenation of CO2 to synthesize multi-carbon compounds (C2-C4). 22 Examples of high-temperature CO2 catalytic conversion are rarely reported. High-temperature CO2 catalytic conversion reactions lead to problems such as high energy consumption and excessive CO2 emissions during the conversion process. Therefore, developing new catalytic systems for low-temperature (≤423K) CO2 to high-value-added products is of great significance. The purpose of this invention is to create a new PtRu catalyst to improve the catalytic selectivity of CO2 hydrogenation to synthesize multi-carbon compounds at low temperatures, while providing a new foundation for the development of high-quality catalysts. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a platinum-ruthenium bimetallic catalyst, which is essentially composed of platinum nanoparticles supported on a support with ruthenium atoms and / or ruthenium clusters embedded in their surface. The invention also includes a method for preparing such catalysts and their application in the catalytic hydrogenation of CO2 to synthesize multi-carbon compounds. The catalyst preparation method provided by this invention, for the first time, achieves the dispersion of Ru atoms in Ru nanoparticles supported on a support into compounds containing single metal atoms in a mixed atmosphere of hydrogen and carbon dioxide, assisted by Pt nanoparticles. This compound is then hydrogenated on the surface of the Pt nanoparticles to form a platinum nanoparticle catalyst supported on a support with ruthenium atoms and / or ruthenium clusters embedded in its surface. This preparation method is carried out at a low temperature, avoiding the formation of a solid solution alloy between the two metals. The catalyst with the structure prepared by this invention exhibits excellent C-reduction properties in the hydrogenation of CO2 to produce multi-carbon hydrocarbons and multi-carbon alcohols. 2+ Selectivity. The above results cannot be deduced from existing knowledge and are of significant inventiveness. In terms of atomic and electronic structure, the catalyst prepared in this invention differs from previously reported PtRu solid solutions or core-shell bimetallic catalysts, which is a key reason for its superior catalytic performance.

[0007] The catalyst provided by the present invention is characterized in that it is basically composed of platinum nanoparticles with ruthenium atoms and / or ruthenium clusters embedded on the surface and supported on a carrier, wherein the platinum / ruthenium atom ratio is 1:2 to 100:1 and the particle size of the platinum nanoparticles with ruthenium atoms and / or ruthenium clusters embedded on the surface is 1 to 5 nanometers.

[0008] In the catalyst described above, the ruthenium cluster is composed of chemically bonded ruthenium atoms.

[0009] The catalyst support is selected from at least one of carbon materials, metal oxides, metal carbonates, molecular sieves, and organic polymer supports.

[0010] In the catalyst support described above, the carbon material can be activated carbon, carbon nanotubes, graphene, etc., the metal oxide can be silicon oxide, titanium oxide, aluminum oxide, iron oxide, manganese oxide, etc., the metal carbonate can be ferrous carbonate, cobalt carbonate, etc., and the organic polymer can be polystyrene, surface sulfonated polystyrene, surface aminated polystyrene, etc.

[0011] The catalysts mentioned above may also contain compounds containing a single ruthenium atom dispersed on the surface of the support.

[0012] The catalysts mentioned above may also contain bipyridine and / or hydrogenated bipyridine.

[0013] The present invention also provides three methods for preparing the catalyst, the main feature of which is that, with the assistance of Pt nanoparticles, Ru atoms in Ru nanoparticles supported on a support are dispersed in a mixed atmosphere of hydrogen and carbon dioxide to form a compound containing a single Ru atom, and then the compound is hydrogenated on the surface of the Pt nanoparticles to form a platinum nanoparticle catalyst with ruthenium atoms and / or ruthenium clusters embedded on the surface of the support.

[0014] The catalyst preparation method of the present invention can be carried out in the following three ways.

[0015] Preparation method one mainly includes the following steps:

[0016] 1.1) Preparation of Pt and Ru metal colloids: Dissolve soluble salts or acids of Pt and Ru in alcohol or alcohol-water mixtures to prepare solutions with metal concentrations of 0.1-50 g / L. Mix the resulting solutions with alcohol or aqueous solutions or alcohol-water mixtures of alkali metal hydroxides. Heat the resulting mixtures at 343-533 K to prepare platinum and ruthenium nanoparticle colloidal solutions, respectively.

[0017] 1.2) Disperse at least one of carbon material, metal oxide, metal carbonate, and organic polymer carrier in an alcohol solution, aqueous solution, or alcohol-water mixture to obtain mixture A. Mix the Ru nanoparticle colloidal solution or Pt nanoparticle colloidal solution prepared in step 1.1) with mixture A to obtain mixture B or C.

[0018] 1.3) Place mixture B or C in a high-pressure autoclave and purge with hydrogen gas. Heat the autoclave at a temperature range of 298 K to 473 K to obtain carrier-supported Ru or Pt nanoparticle materials.

[0019] 1.4) Disperse the Ru or Pt nanoparticle material supported on the support prepared in step 1.3) in water, alcohol or alcohol-water mixture, add the Pt or Ru nanoparticle colloidal solution prepared in step 1.1) to the resulting mixture, and fill the reactor with hydrogen and carbon dioxide gas. Heat the system in the temperature range of 363K to 433K. The resulting solid product is separated, washed and dried to obtain the catalyst.

[0020] In the above preparation method, preferably, the hydrogen pressure in step 1.3) is 0.1-15 kPa, the initial partial pressure ratio of CO2 to hydrogen in step 1.4) is 1:3 to 3:1, and the total pressure is 0.1 to 15 MPa, preferably 5 MPa. The alcohol is selected from at least one of monohydric alcohols and dihydric alcohols having 1-6 carbon atoms, such as ethylene glycol, ethanol, isopropanol, and n-butanol.

[0021] Preparation method two mainly includes the following steps:

[0022] 2.1) Add bipyridine to the ruthenium nanoparticle colloidal solution prepared in step 1.1) of preparation method one above to prepare Ru nanocluster aggregate solids formed by bipyridine coordination bonding. Separate and disperse the solids in ketone and / or alcohol solvents, and add the platinum nanoparticle colloidal solution prepared in step 1.1) of preparation method one to obtain a core-shell aggregate with Pt nanoparticles as the outer layer and ruthenium nanoclusters as the inner layer.

[0023] 2.2) The shell-core aggregate is dispersed in water and / or an alkane solvent and the resulting mixture is placed in an autoclave. Hydrogen and carbon dioxide gases are introduced into the autoclave, and the system is heated in the temperature range of 363K to 433K. The resulting solid product is separated, washed, and dried to obtain the catalyst.

[0024] In the second preparation method described above, the molar ratio of bipyridine to Ru in step 2.1) is 0.1 to 2; the initial partial pressure ratio of CO2 to hydrogen in step 2.2) is 1:3 to 3:1, and the total pressure is 0.1 to 15 MPa. Hydrogenated bipyridine is generated by catalytic hydrogenation of bipyridine during catalyst preparation. The solvent in step 2.1 can be an organic solvent such as an alcohol or ketone, and the alkane solvent in step 2.2 can be cyclohexane or a chain alkane.

[0025] Preparation method three mainly includes the following steps:

[0026] 3.1) The carrier-loaded Ru nanoparticle material was prepared according to steps 1.1) to 1.3) of preparation method one;

[0027] 3.2) Disperse the Ru nanoparticle material supported by the carrier prepared in step 3.1) in an organic solvent, add the Pt nanoparticle colloidal solution prepared in step 1.1) of the preparation method to the mixed system, stir, and prepare the material supported by Ru and Pt nanoparticles. The organic solvent is selected from at least one of alcohols, ketones and aldehydes with 1-6 carbon atoms.

[0028] 3.3) The material with Ru and Pt nanoparticles supported on the support prepared in step 3.2) is dispersed in water and / or alkane solvent, and the resulting mixture is placed in an autoclave. Hydrogen and carbon dioxide gas are introduced into the autoclave, and the system is heated in the temperature range of 363K to 433K. The resulting solid product is separated, washed, and dried to obtain the catalyst.

[0029] In the above preparation method three, the initial partial pressure ratio of CO2 to hydrogen in step 3.3) is 1:3 to 3:1, and the total pressure is 0.1 to 15 MPa. The alkane solvent can be cyclohexane or chain alkanes.

[0030] The method of treating Pt and Ru nanoparticles loaded on a support in water and / or alkanes with a mixed atmosphere of hydrogen and carbon dioxide in the temperature range of 363K to 433K, thereby dispersing Ru atoms in the Ru nanoparticles loaded on the support to form compounds containing individual Ru atoms with the assistance of Pt nanoparticles, is also within the scope of protection of this invention.

[0031] Catalysts prepared by the preparation method of the present invention are also within the scope of protection of the present invention.

[0032] The application of the catalyst provided by this invention in the catalytic hydrogenation of carbon dioxide to prepare multicarbon hydrocarbons and multicarbon alcohols is also within the scope of protection of this invention.

[0033] The above-mentioned preparation of multicarbon hydrocarbons and multicarbon alcohols by carbon dioxide hydrogenation can be carried out in water or a mixture of water and alkanes.

[0034] In summary, the catalyst, its preparation method, and its application of the present invention are based on the following novel discovery: with the assistance of Pt nanoparticles, Ru atoms in Ru nanoparticles supported on a support are dispersed in a mixed atmosphere of hydrogen and carbon dioxide to form compounds containing individual Ru atoms. These compounds are then hydrogenated on the surface of the Pt nanoparticles to form a platinum nanoparticle catalyst with ruthenium atoms and / or ruthenium clusters embedded on the surface, supported on a support. This type of catalyst catalyzes the hydrogenation of carbon dioxide at low temperatures (≤423 K) to prepare multi-carbon hydrocarbons (C2-C4). 22 ) and polyols (C2-C 16 C showed a high level in the response. 2+ Selectivity. For example, in Example 1, C in the catalytic reaction product... 2+ The selectivity is greater than 90%, the highest value reported to date. These results cannot be deduced from existing knowledge and represent significant inventiveness. The catalyst prepared in this invention exhibits a different atomic and electronic structure from previously reported PtRu solid solutions or core-shell bimetallic catalysts, which is a key reason for its superior catalytic properties. Attached Figure Description

[0035] Figure 1 Transmission electron microscopy (TEM) image (A) and elemental distribution image (BD) of Ru-co-Pt / C prepared in Example 1.

[0036] Figure 2 Transmission electron microscopy (TEM) image of Ru single-atom compounds in the Ru-co-Pt / C sample prepared in Example 1.

[0037] Figure 3Transmission electron microscopy (TEM) images (A) and (B) of Ru-bi-Pt / C prepared for Example 1, and the metal particle size distributions (C) and (D) of Ru-bi-Pt / C.

[0038] Figure 4 X-ray photoelectron spectra (A, B) of Pt and Ru in Ru-co-Pt / C prepared in Example 1, and extended X-ray absorption fine spectra (C, D) of Pt L3 edge and Ru K edge.

[0039] Figure 5 X-ray photoelectron spectra of N in Ru-bi-Pt / C and Ru-co-Pt / C prepared in Example 1.

[0040] Figure 6 The distribution diagram shows the products generated by the Ru-co-Pt / C catalytic CO2 hydrogenation reaction prepared in Example 1.

[0041] Figure 7 The mass spectrum (AC) of the multicarbon hydrocarbons generated by the Ru-co-Pt / C catalytic CO2 hydrogenation reaction in Example 1 is shown.

[0042] Figure 8 The images shown are transmission electron microscope (TEM) images of Ru-co-Pt / TiO2 and selected area elemental distribution images from Example 6.

[0043] Figure 9 The images show transmission electron microscopy (TEM) images and selected area elemental distribution (AC) maps of Ru-bi-Ru / C prepared in Comparative Example 1, and TEM images and selected area elemental distribution (DF) maps of Ru-bi-Ru / C samples treated with CO2 and H2.

[0044] Figure 10 The images shown are transmission electron microscopy (TEM) images and selected area elemental distribution (AC) maps of Pt-bi-Pt / C prepared in Comparative Example 2, and TEM images and elemental distribution (DF) maps of Pt-bi-Pt / C samples treated with CO2 and H2. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments. Unless otherwise specified, the methods described are conventional methods. Unless otherwise specified, the raw materials are all available from publicly available commercial sources.

[0046] Example 1

[0047] A 0.26M NaOH ethylene glycol solution and a 1g / 50mL H₂PtCl₆·nH₂O ethylene glycol solution were mixed with stirring. The resulting mixture was then microwaved at 160℃ under a nitrogen atmosphere for 5 minutes to obtain a Pt colloidal solution. A Ru colloidal solution was prepared using a similar method. (The last sentence appears to be incomplete and possibly refers to a specific concentration of 5.9 × 10⁻⁶.) -3 4,4'-bipyridine was dissolved in 20 mL of acetone, and then 1 mL of Ru colloidal solution was added. The mixture was stirred for 5 h. Centrifugation yielded 4,4'-bipyridine-linked Ru nanoparticles (Ru-bi-Ru). This precipitate was dispersed in 20 mL of acetone, and 2 mL of Pt colloidal solution was added to the system. After stirring for 24 h, 4,4'-bipyridine-linked Ru and Pt nanoparticles (Ru-bi-Pt) were obtained. 55 mg of activated carbon was added to the above system, and stirring for 24 h yielded activated carbon-supported 4,4'-bipyridine-linked Ru and Pt nanoparticle assemblies (Ru-bi-Pt / C). Ru-bi-Pt / C was placed in a high-pressure reactor, and 5 mL of H2O and 5 mL of cyclohexane solvent were added. A mixed gas of CO2 and H2 at 5 MPa was introduced (P CO2 / P H2 =1 / 3), Ru-bi-Pt / C was treated at 130℃.

[0048] See Figures 1 to 7 Electron microscopy and extended X-ray absorption fine spectroscopy characterization results showed that Ru nanoclusters in the treated sample (Ru-co-Pt / C) were dispersed, forming Ru single-atom compounds or small Ru clusters grown on Pt nanoparticles, with an average metal particle size of 2.1 nm. ICP tests indicated that the Pt and Ru loadings in Ru-co-Pt / C were 14.3% and 6.7%, respectively. X-ray photoelectron spectroscopy showed that both Ru and Pt existed in metallic form in Ru-co-Pt / C, and the sample contained N element. Based on extended X-ray absorption fine spectroscopy fitting of the Pt L3 edge and Ru K edge of Ru-bi-Pt / C and Ru-co-Pt / C, the Ru-Ru coordination numbers in Ru-bi-Pt / C and Ru-co-Pt / C were 4.77 and 1.80, respectively, indicating that Ru atoms in the Ru nanoparticles were dispersed during the Ru-bi-Pt / C treatment. In Ru-co-Pt / C, the Pt / Ru atomic ratio is close to 1:1. The coordination number of Pt-Ru is 2.51, while that of Ru-Pt is 5.86, indicating that Ru is mainly distributed on the particle surface in the bimetallic particles. The coordination number of Pt-Pt is 6.59, indicating that the central part of the bimetallic particles is mainly composed of Pt atoms. Catalytic performance experiments show that small-sized Ru clusters grown on the surface of Pt nanoparticles can catalyze the hydrogenation of CO2 to multi-carbon compounds (C2-C) with high selectivity at 130℃.22 (The C2+ product selectivity is as high as 90%).

[0049] Example 2

[0050] In Example 1, the pressure of the CO2 and H2 mixed gas was changed to 10 MPa, and the mixed gas ratio was changed to P. CO2 / P H2 =3 / 1, with other preparation and treatment conditions remaining unchanged. Electron microscopy characterization results showed that the Ru nanoclusters in the treated samples were dispersed, forming Ru single-atom compounds or small-sized Ru clusters grown on Pt nanoparticles.

[0051] Example 3

[0052] In Example 1, the support was changed to MnCO3, while other preparation and treatment conditions remained unchanged. Electron microscopy characterization showed that the Ru nanoclusters in the treated sample dispersed, forming Ru single-atom compounds or small Ru clusters grown on Pt nanoparticles. Catalytic performance experiments indicated that the treated sample could selectively catalyze the hydrogenation of CO2 into multi-carbon compounds (C2-C4). 22 The C2+ product selectivity was 30%.

[0053] Example 4

[0054] The carrier in Example 1 was changed to MoO x Other preparation and processing conditions remained unchanged. Electron microscopy characterization results showed that the Ru nanoclusters in the treated samples were dispersed, forming Ru single-atom compounds or small Ru clusters grown on Pt nanoparticles.

[0055] Example 5

[0056] 0.35 g of SiO2, 1 mL of Ru colloid, and 30 mL of H2O were placed in a reaction vessel, and hydrogen gas at 2 MPa was introduced. The reaction vessel was heated to 150 °C to obtain a Ru / SiO2 sample. Ru / SiO2 was dispersed in ethanol, and 2 mL of Pt colloid was added, followed by stirring to obtain a Ru-Pt / SiO2 sample. Ru-Pt / SiO2 was then tested at 120 °C using a mixed solvent of water and cyclohexane with CO2 and H2 (P2O2). CO2 / P H2 =1 / 3,P 总 After treatment with a mixed gas of 6 MPa, the results of aberration electron microscopy showed that Ru nanoclusters in the treated samples were dispersed, forming Ru single-atom compounds or small Ru clusters grown on Pt nanoparticles.

[0057] Example 6

[0058] In Example 2, the support was replaced with TiO2, while other preparation and treatment conditions remained unchanged. Electron microscopy characterization showed that the Ru nanoclusters in the treated sample (Ru-co-Pt / TiO2) were dispersed, forming Ru single-atom compounds or small-sized Ru clusters grown on Pt nanoparticles. Figure 8 ).

[0059] Example 7

[0060] Ru and Pt nanoparticle assemblies (Ru-bi-Pt / ZSM-5) supported on ZSM-5 molecular sieves were prepared using the method described in Example 2. The Ru-bi-Pt / ZSM-5 was then treated using the method described in Example 1. Electron microscopy characterization showed that the Ru nanoclusters in the treated samples were dispersed, forming Ru single-atom compounds or small Ru clusters grown on Pt nanoparticles.

[0061] Example 8

[0062] Ru and Pt colloidal solutions, a carbon support, and water were placed in a reaction vessel, and hydrogen gas at 5 MPa was introduced. The reaction vessel was heated to 130 °C to obtain the Ru-Pt / C sample. Ru-Pt / C was then tested at 130 °C using a mixed solvent of water and cyclohexane with CO2 and H2 (P2O3). CO2 / P H2 =2 / 1,P 总 After treatment with a mixed gas of 10 MPa, electron microscopy characterization showed that Ru nanoclusters in the treated samples were dispersed, forming Ru single-atom compounds or small Ru clusters grown on Pt nanoparticles.

[0063] Example 9. A Ru / C sample was prepared by dispersing a Ru colloidal solution and a carbon support in ethanol and stirring. The Ru / C sample, Pt colloidal solution, and water were placed in a reaction vessel, and hydrogen gas at 0.5 MPa was introduced. The reaction vessel was heated to 150°C to obtain a Ru-Pt / C sample. The Ru-Pt / C sample was then dispersed in a mixed solvent of water and cyclohexane, and CO2 and H2 (P2O3) were introduced into the vessel. CO2 / P H2 =3 / 1,P 总 =3MPa), the reaction vessel was heated at 120℃, and the solid product was washed and dried to obtain the catalyst sample. Electron microscopy characterization results showed that Ru atoms in the Ru nanoclusters of the prepared sample were dispersed, forming Ru single-atom compounds or small Ru clusters grown on Pt nanoclusters.

[0064] Compare with Example 1

[0065] Ru-bi-Ru was prepared using the method described in Example 1, and then loaded onto a C support to obtain a Ru-bi-Ru / C sample. The Ru-bi-Ru / C sample was tested at 130°C using a mixed solvent of water and cyclohexane with CO2 and H2 (P). CO2 / P H2 =1 / 3,P 总 After treatment with a mixed gas at 6 MPa, aberration-corrected electron microscopy characterization showed that Ru nanoclusters did not disperse in the treated sample. Figure 9 ).

[0066] Compare with Example 2

[0067] By replacing the Ru colloid in Comparative Example 1 with Pt colloid while keeping other conditions unchanged, a Pt-bi-Pt / C sample was prepared. The Pt-bi-Pt / C sample was tested at 130°C using a mixed solvent of water and cyclohexane with CO2 and H2 (P... CO2 / P H2 =1 / 3,P 总 Treatment with a mixed gas at 6 MPa and spherical aberration electron microscopy characterization showed that the Pt nanoclusters in the treated sample did not disperse. Figure 10 ).

Claims

1. A platinum-ruthenium bimetallic catalyst, characterized in that, The catalyst is essentially composed of platinum nanoparticles with ruthenium atoms and / or ruthenium clusters embedded on the surface, supported on a carrier. The atomic ratio of platinum to ruthenium is 1:2 to 100:

1. The particle size of the platinum nanoparticles with ruthenium atoms and / or ruthenium clusters embedded on the surface is 1 to 5 nanometers, wherein the ruthenium clusters are composed of chemically bonded ruthenium atoms. The preparation method of the platinum-ruthenium bimetallic catalyst includes the following steps: treating Pt and Ru nanoparticles supported on the carrier in water and / or alkanes in a mixed atmosphere of hydrogen and carbon dioxide at a temperature range of 363 K to 433 K. With the assistance of Pt nanoparticles, Ru atoms in Ru nanoparticles supported on the carrier are dispersed to form platinum nanoparticles with ruthenium atoms and / or ruthenium clusters embedded on the surface, supported on the carrier.

2. The platinum-ruthenium bimetallic catalyst according to claim 1, characterized in that, The carrier is selected from at least one of carbon materials, metal oxides, metal carbonates, molecular sieves, and organic polymer carriers.

3. The platinum-ruthenium bimetallic catalyst according to claim 2, characterized in that, The carbon material is selected from one or more of activated carbon, carbon nanotubes, and graphene; the metal oxide is selected from one or more of titanium oxide, aluminum oxide, iron oxide, and manganese oxide; the metal carbonate is selected from ferrous carbonate and / or cobalt carbonate; and the organic polymer is selected from one or more of polystyrene, surface-sulfonated polystyrene, and surface-aminated polystyrene.

4. The platinum-ruthenium bimetallic catalyst according to claim 1, characterized in that, The catalyst contains bipyridine and / or hydrogenated bipyridine.

5. The method for preparing the platinum-ruthenium bimetallic catalyst according to any one of claims 1-4, characterized in that, The preparation method of the platinum-ruthenium bimetallic catalyst includes the following steps: treating Pt and Ru nanoparticles loaded on a support in water and / or alkanes with a mixed atmosphere of hydrogen and carbon dioxide in the temperature range of 363K to 433K; with the assistance of Pt nanoparticles, dispersing Ru atoms in Ru nanoparticles loaded on the support to form platinum nanoparticles loaded on the support with ruthenium atoms and / or ruthenium clusters embedded on the surface.

6. The preparation method according to claim 5, characterized in that, The initial partial pressure ratio of CO2 to hydrogen in the hydrogen and carbon dioxide mixed atmosphere is 1:3 to 3:1, and the total pressure is 0.1 to 15 MPa.

7. The preparation method according to claim 5 or 6, characterized in that, Includes the following steps: 1.1) Preparation of Pt and Ru metal colloids: Soluble salts or acids of Pt and Ru are dissolved in alcohol or alcohol-water mixtures to prepare solutions with metal concentrations of 0.1-50 g / L. The resulting solutions are mixed with alcohol solutions or aqueous solutions or alcohol-water mixtures of alkali metal hydroxides. The resulting mixtures are heated at 343-533 K to prepare platinum and ruthenium nanoparticle colloidal solutions, respectively. 1.2) Disperse at least one of carbon material, metal oxide, metal carbonate, and organic polymer carrier in an alcohol solution, aqueous solution, or alcohol-water mixture to obtain mixture A. Mix the Ru nanoparticle colloidal solution or Pt nanoparticle colloidal solution prepared in step 1.1) with mixture A to obtain mixture B or C. 1.3) Place mixture B or C in a high-pressure autoclave and purge with hydrogen gas. Heat the autoclave at a temperature range of 298 K to 473 K to obtain carrier-supported Ru or Pt nanoparticle materials. 1.4) Disperse the Ru or Pt nanoparticle material supported on the support prepared in step 1.3) in water, alcohol or alcohol-water mixture, add the Pt or Ru nanoparticle colloidal solution prepared in step 1.1) to the resulting mixture, and fill the reactor with hydrogen and carbon dioxide gas. Heat the system in the temperature range of 363K to 433K. The resulting solid product is separated, washed and dried to obtain the catalyst.

8. The preparation method according to claim 7, characterized in that, The alcohol is selected from at least one of monohydric alcohols and dihydric alcohols having 1-6 carbon atoms.

9. The preparation method according to claim 5 or 6, characterized in that, Includes the following steps: 2.1) Prepare a ruthenium nanoparticle colloidal solution according to step 1.1) of claim 7, add bipyridine to it to prepare a Ru nanocluster aggregate solid formed by coordination bonding of bipyridine, separate and disperse the solid in a ketone and / or alcohol solvent, add a platinum nanoparticle colloidal solution prepared according to step 1.1) of claim 7 to it to obtain a core-shell aggregate with Pt nanoparticles as the outer layer and ruthenium nanoclusters as the inner layer; 2.2) The core-shell aggregates supported on the support are dispersed in water and / or alkane solvents, and the resulting mixture is placed in an autoclave. Hydrogen and carbon dioxide gases are introduced into the autoclave, and the system is heated in the temperature range of 363K to 433K. The resulting solid product is separated, washed, and dried to obtain the catalyst.

10. The preparation method according to claim 9, characterized in that, In step 2.1), the molar ratio of bipyridine to Ru is 0.1 to 2.

11. The preparation method according to claim 5 or 6, characterized in that, Includes the following steps: 3.1) The carrier-loaded Ru nanoparticle material is prepared according to steps 1.1) to 1.3) of claim 7; 3.2) Disperse the Ru nanoparticle material supported on the carrier in an organic solvent, add the Pt nanoparticle colloidal solution prepared according to step 1.1) of claim 7 to the mixed system, stir, and prepare the material supported on the carrier and Pt nanoparticles; 3.3) The material with Ru and Pt nanoparticles supported on the support prepared in step 3.2) is dispersed in water and / or alkane solvent, and the resulting mixture is placed in an autoclave. Hydrogen and carbon dioxide gas are introduced into the autoclave, and the system is heated in the temperature range of 363K to 433K. The resulting solid product is separated, washed, and dried to obtain the catalyst.

12. The application of the platinum-ruthenium bimetallic catalyst according to any one of claims 1-4 in the catalytic hydrogenation of carbon dioxide to prepare multicarbon hydrocarbons and multicarbon alcohols.

13. The application according to claim 12, characterized in that, The catalytic hydrogenation of carbon dioxide is carried out in water or a mixture of water and alkanes.

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