A method for constructing a metal-support strong interaction in a supported metal catalyst by using a molten salt

Abstract

This invention discloses a method for constructing a supported metal catalyst with strong metal-support interactions induced by molten salt, belonging to the field of heterogeneous catalyst preparation technology. The method comprises the following steps: thoroughly covering the supported metal catalyst with metal salt powder, heating it to above the melting point of the metal salt under an inert atmosphere to melt the metal salt powder, and holding at this temperature for 0.1–2 hours; after cooling to room temperature, washing, centrifuging, and drying are performed sequentially to obtain the supported metal catalyst with strong metal-support interactions induced by molten salt. This invention achieves wide-temperature-range construction of SMSI in oxide-supported metal-based catalyst systems in a low-cost, simple, and efficient manner, and can also expand the application scenarios of SMSI in non-reducing supported catalyst systems.

Description

Technical Field

[0001] This invention relates to the field of heterogeneous catalyst preparation technology, and in particular to a method for constructing a supported metal catalyst with strong metal-support interaction in a molten salt-induced manner. Background Technology

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Supported metal catalysts are catalytic materials in which metal sites are anchored on the surface of a support, and they are widely used in synthetic chemistry, energy conversion, and pollution treatment. In these materials, the ubiquitous interaction between the support and the metal significantly influences the geometry and electronic structure of the active metal phase, thus providing a new dimension for the performance regulation of metal catalysts and greatly expanding the possibilities for optimizing catalyst selectivity, activity, and stability. Therefore, understanding and utilizing the interaction between metal and support is an important research topic in the field of heterogeneous catalysis.

[0004] Strong Metal-Support Interaction (SMSI) is a special interaction that mainly exists between metals and reducible oxide supports. Specifically, it manifests as: (1) the active metal phase is covered by an amorphous oxide coating layer; (2) the adsorption capacity of the active metal centers for small gas molecules (CO, H2, etc.) disappears; and (3) the active metal phase is dispersed or reconstructed on the support surface. The fundamental reason for this is that the active metal atoms bond with the metal ions in the support. SMSI can not only significantly stabilize the structure of the active metal phase and improve the stability of the catalyst under harsh reaction environments such as high temperature, but also regulate the activity and selectivity of the catalyst through interfacial bonding or electronic interactions. Therefore, it has extremely important applications in industrial reactions such as selective hydrogenation, water-gas conversion, and methanol steam reforming.

[0005] In practical applications, the common method for constructing SMSI is high-temperature heat treatment (>500℃) in a gas-phase environment. However, the high surface energy of the metal active phase often leads to sintering at such high temperatures, severely limiting the application of SMSI in the field of catalyst structure and performance control. Furthermore, traditional high-temperature gas-phase heat treatment methods are difficult to induce the construction of SMSI on metal catalysts supported on non-reducible supports. This may be because non-reducible supports are difficult to activate in a gas-phase environment, inhibiting the migration of support atoms and subsequent bonding with the metal active phase. This significantly impacts both the theoretical research and practical application of SMSI.

[0006] Patent CN 116532127 A (publication date: August 4, 2023) discloses a method for inducing strong metal-support interactions in metal catalysts using molten metal as an inducer, such as Li, Na, K, Mg, Ca, Zn, Cd, Al, Ga, In, Sn, Pb, Sb, and Bi, which can effectively improve the stability of metal catalysts in high-temperature environments. However, elemental metal powders are relatively hazardous and easily oxidized, requiring stringent environmental conditions. Furthermore, the variety of elemental metals is limited, and their melting points are generally high, thus restricting the temperature applicability of this method. Additionally, this method requires a large amount of metal powder, which needs to be dissolved in concentrated hydrochloric acid after calcination. The dissolution process generates hydrogen gas, posing a significant risk if scaled up for production.

[0007] Therefore, it is evident that providing a method for inducing strong metal-support interactions in supported metal catalysts that has wide temperature applicability, high safety in the preparation process, and low cost is an urgent problem to be solved. Summary of the Invention

[0008] In view of this, the present invention provides a method for the molten salt-induced construction of strong metal-support interactions in supported metal catalysts. Utilizing the strong polarization capability of molten salts, the method achieves the induced construction of SMSI at relatively low temperatures (<350℃). Simultaneously, the high atomic density at the molten salt-support solid-liquid interface effectively hinders the sintering of the metal active phase. Furthermore, the wide variety of selectable molten salts allows for the induced construction of SMSI within a broad temperature range (150-1000℃). Moreover, the process is safer and more environmentally friendly.

[0009] In a first aspect, the present invention provides a method for constructing a supported metal catalyst with strong metal-support interactions induced by molten salt, comprising the following steps:

[0010] Supported metal catalysts are synthesized by a wet chemical method, wherein the supported metal catalysts include oxide supports and metal nanoparticles, clusters or single atoms;

[0011] After fully covering the supported metal catalyst with metal salt powder, the temperature is raised to above the melting point of the metal salt under an inert atmosphere to melt the metal salt powder, and the temperature is maintained for 0.1 to 2 hours. After cooling to room temperature, the catalyst is washed, centrifuged and dried in sequence to obtain the supported metal catalyst with strong metal-support interaction induced by molten salt.

[0012] Preferably, the mass percentage of metal nanoparticles, clusters, or single atoms in the supported metal catalyst is 0.01–60 wt%.

[0013] Preferably, the oxide carrier includes one or more of titanium dioxide, cerium dioxide, tin dioxide, aluminum oxide, silicon dioxide, niobium pentoxide, vanadium trioxide, manganese dioxide, iron oxide, tantalum pentoxide, magnesium oxide, or zinc oxide.

[0014] Preferably, the metal in the metal nanoparticles, clusters or single atoms includes one or more of platinum, iridium, gold, palladium, ruthenium, rhodium, osmium, copper, zinc, silver, iron, cobalt or nickel.

[0015] Preferably, the metal salt includes one or more of the following: nitrates, chlorides, thiocyanates, tetrachloroaluminates, sulfates, carbonates, fluorides, bromides, iodides, or cyanates of lithium, sodium, potassium, magnesium, calcium, barium, strontium, iron, zinc, rubidium, chromium, cobalt, nickel, molybdenum, tungsten, or tin.

[0016] Preferably, the mass ratio of the supported metal catalyst to the metal salt powder is 3-10 mg: 1 g.

[0017] Preferably, the inert atmosphere is argon or nitrogen; the heating rate is 4–10 °C / min.

[0018] Preferably, the washing process involves washing with water and ethanol 2 to 4 times in sequence; the drying temperature is 40 to 100°C, and the drying time is 2 to 20 hours.

[0019] Secondly, the present invention provides a supported metal catalyst prepared by the above method after molten salt-induced construction of a metal-support with strong interaction.

[0020] Thirdly, the present invention provides the application of the above-mentioned supported metal catalyst with strong metal-support interaction induced by molten salt, the application including using the supported metal catalyst with strong metal-support interaction induced by molten salt as a catalyst for hydrogen evolution reaction, oxygen evolution reaction, hydrogen oxidation reaction, oxygen reduction reaction, carbon dioxide reduction reaction, methane oxidation or formic acid oxidation.

[0021] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0022] (1) This invention achieves the construction of SMSI in oxide-supported metal-based catalyst systems in a low-cost, simple, and efficient manner. There are many types of molten salts, and the application range is wide. The construction of SMSI at a lower temperature can be achieved by selecting molten salts with low melting points. In addition, the high atomic density at the molten salt-support interface can effectively prevent the sintering and agglomeration of metal active centers, effectively avoid the failure of catalyst structure under high temperature environment, and enhance the application potential of SMSI in high temperature environment. Therefore, the method provided by this invention can realize the construction of supported metal catalyst SMSI in a wide temperature range of 150-1000℃; and realizes the wide temperature range controllable construction of SMSI on metal catalysts.

[0023] (2) This invention uses molten salt and utilizes the high polarity of molten salt ions to effectively activate non-reducing metal supports, improve the migration ability of support ions and the bonding ratio of metal-support interface, successfully construct SMSI, expand the application scenarios of SMSI in non-reducing support catalyst systems; and can extend SMSI to complex and multi-component reaction systems and material systems. Attached Figure Description

[0024] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0025] Figure 1 The TEM images are of the titanium dioxide-supported iridium nanoclusters catalyst before and after the molten sodium nitrate-induced construction of SMSI in Example 1 of this invention.

[0026] Figure 2 The CO-DRIFTS spectra of the titanium dioxide-supported iridium nanoclusters catalyst before and after the molten sodium nitrate-induced construction of SMSI in Example 1 of this invention are shown.

[0027] Figure 3 The EXAFS wavelet transform spectrum of the titanium dioxide-supported iridium nanocluster catalyst after molten sodium nitrate-induced construction of SMSI in Example 1 of this invention;

[0028] Figure 4 The CO-DRIFTS spectrum of the titanium dioxide-supported iridium nanocluster catalyst induced by high-temperature hydrogen-argon mixed gas to construct SMSI in Comparative Example 1 of this invention.

[0029] Figure 5 The TEM images are of the titanium dioxide-supported platinum nanoparticle catalyst before and after the molten sodium nitrate-induced construction of SMSI in Example 2 of this invention.

[0030] Figure 6 The TEM image shows the titanium dioxide-supported platinum nanoparticle catalyst induced by high-temperature hydrogen-argon mixture in Comparative Example 2 of this invention.

[0031] Figure 7 This is a TEM image of the titanium dioxide-supported platinum nanoparticle catalyst induced by molten sodium tetrachloroaluminate to construct SMSI in Example 3 of the present invention.

[0032] Figure 8 The CO-DRIFTS spectra of the iridium nanoclusters supported on cerium dioxide before and after the molten sodium nitrate-induced construction of SMSI in Example 4 of this invention are shown.

[0033] Figure 9 The EXAFS wavelet transform spectra of the iridium nanocluster catalyst supported on cerium dioxide before and after the molten sodium nitrate-induced construction of SMSI in Example 4 of this invention;

[0034] Figure 10 The CO-DRIFTS spectra of the tin dioxide-supported iridium nanoparticle catalyst before and after the molten sodium nitrate-induced construction of SMSI in Example 5 of this invention are shown.

[0035] Figure 11 The EXAFS wavelet transform spectra of the tin dioxide-supported iridium nanoparticle catalyst before and after the molten sodium nitrate-induced construction of SMSI in Example 5 of this invention are shown. Detailed Implementation

[0036] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] This invention provides a method for constructing a supported metal catalyst with strong metal-support interactions induced by molten salt, comprising the following steps:

[0038] Supported metal catalysts are synthesized by a wet chemical method, wherein the supported metal catalysts include oxide supports and metal nanoparticles, clusters or single atoms;

[0039] After fully covering the supported metal catalyst with metal salt powder, the temperature is raised to above the melting point of the metal salt under an inert atmosphere to melt the metal salt powder, and the temperature is maintained for 0.1 to 2 hours. After cooling to room temperature, the catalyst is washed, centrifuged and dried in sequence to obtain the supported metal catalyst with strong metal-support interaction induced by molten salt.

[0040] In existing technologies, the construction of strong metal-support interactions often involves high-temperature heat treatment (>500℃) in a gas-phase environment. However, the high surface energy of the active metal phase often leads to sintering at such high temperatures, severely limiting the practical application of SMSI in the field of catalyst structure and performance regulation. Furthermore, traditional high-temperature gas-phase heat treatment methods are difficult to induce SMSI construction of metal catalysts supported on non-reducible supports. This may be because non-reducible supports are difficult to activate in a gas-phase environment, inhibiting the migration of support atoms and subsequent bonding with the active metal phase. This significantly impacts both the theoretical research and practical application of SMSI.

[0041] The inventors discovered that when using molten salt-induced construction of SMSI, the high atomic density at the molten salt-support interface effectively hinders the sintering and agglomeration of metal active centers, effectively preventing catalyst structure failure under high-temperature conditions and enhancing the application potential of SMSI in high-temperature environments. Simultaneously, the high polarity of molten salt ions effectively activates non-reducible metal supports, improving the migration ability of support ions and the bonding ratio at the metal-support interface, successfully constructing SMSI and expanding its application scenarios in non-reducible supported catalyst systems. Furthermore, the variety of molten salts and their large differences in melting points enable the construction of SMSI within a temperature range of 150–1000℃.

[0042] This invention does not impose any particular limitation on the steps for synthesizing supported metal catalysts via wet chemical methods; methods commonly used in the art can be employed. Preferably, this invention involves mixing the metal precursor and oxide support in a solvent, evaporating the solvent, and then calcining the mixture under a reducing or protective gas to obtain the catalyst.

[0043] This invention does not impose any special restrictions on the loading amount of metal nanoparticles, clusters, or single atoms in the supported metal catalyst, and the mass percentage is 0.01 to 60 wt%.

[0044] In this invention, the oxide support comprises one or more of titanium dioxide, cerium dioxide, tin dioxide, aluminum oxide, silicon dioxide, niobium pentoxide, vanadium trioxide, manganese dioxide, iron oxide, tantalum pentoxide, magnesium oxide, or zinc oxide. Among these, silicon dioxide and aluminum oxide are non-reducing oxide supports.

[0045] The present invention does not impose any special restrictions on the metal in the metal nanoparticles, clusters or single atoms, and may select one or more of platinum, iridium, gold, palladium, ruthenium, rhodium, osmium, copper, zinc, silver, iron, cobalt or nickel.

[0046] In this invention, the metal salt includes one or more of the following: nitrates, chlorides, thiocyanates, tetrachloroaluminates, sulfates, carbonates, fluorides, bromides, iodides, or cyanates of lithium, sodium, potassium, magnesium, calcium, barium, strontium, iron, zinc, rubidium, chromium, cobalt, nickel, molybdenum, tungsten, or tin. The metal salts selected in this invention have a wide range and a large melting point span. For example, potassium thiocyanate has a melting point of 173°C, allowing for the construction of SMSI at temperatures above 173°C; magnesium chloride has a melting point of 714°C, allowing for the construction of SMSI at temperatures above 714°C, such as 800–1000°C.

[0047] In this invention, the mass ratio of the supported metal catalyst to the metal salt powder is 3–10 mg: 1 g. The metal salt powder needs to fully coat the supported metal catalyst to maximize the effect of the molten salt.

[0048] In this invention, the inert atmosphere is argon or nitrogen. The inert gas effectively protects the reaction process and prevents impurity gases from affecting the SMSI construction process. In this invention, the heating rate is 4–10 °C / min.

[0049] In this invention, the specific washing steps involve washing with water and ethanol 2 to 4 times sequentially. Washing is to remove water-soluble metal salts to obtain a pure supported metal catalyst with strong metal-support interactions induced by molten salt. The drying temperature in this invention is 40–100°C, and the drying time is 2–20 hours.

[0050] The present invention also provides a supported metal catalyst prepared by the above method after molten salt-induced construction of a metal-support with strong interaction.

[0051] This invention also provides applications for the supported metal catalysts constructed with strong metal-support interactions induced by molten salt, including using these catalysts as catalysts for hydrogen evolution reaction, oxygen evolution reaction, hydrogen oxidation reaction, oxygen reduction reaction, carbon dioxide reduction reaction, methane oxidation, or formic acid oxidation reaction. Because SMSI is successfully constructed on supported metal catalysts, the interfacial bonding between the oxide support and the metal can generate unique electronic and structural effects, effectively improving the catalytic performance, stability, and selectivity of the catalyst.

[0052] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0053] Example 1

[0054] A method for constructing SMSI on titanium dioxide-supported iridium nanoclusters induced by molten sodium nitrate, the specific steps of which are as follows:

[0055] (1) Preparation method of titanium dioxide support:

[0056] First, 1 mL of titanium trichloride solution was dissolved in a mixture of 30 mL of ethylene glycol and 1 mL of deionized water. After stirring appropriately with a glass rod, the solution was transferred to a 50 mL Teflon-lined stainless steel autoclave. The autoclave was then heated at 150°C for 4 hours in a forced-air drying oven. The resulting sample was washed three times with deionized water and three times with ethanol, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain the titanium dioxide support.

[0057] (2) Preparation method of titanium dioxide supported iridium nanocluster catalyst:

[0058] First, 40 mg of acetylacetone iridium precursor was mixed with 100 mg of pre-prepared titanium dioxide support in a mortar, and an appropriate amount of ethanol was added before thorough grinding. The mixed powder was placed in a tube furnace saturated with a 10% hydrogen-argon mixture and heated to 300 °C at a rate of 5 °C / min, and held at that temperature for 60 min to obtain titanium dioxide-supported iridium nanoclusters catalyst.

[0059] (3) Method for inducing the construction of SMSI using molten sodium nitrate:

[0060] The 20 mg titanium dioxide-supported iridium nanoclusters catalyst obtained in step (1) was thoroughly covered with 3 g sodium nitrate powder (melting point 306.8 °C). The mixture was then heated to 350 °C at a rate of 5 °C / min and held for 30 min in a tube furnace under argon atmosphere. After cooling to room temperature, the resulting calcined mixed solid was washed three times each with deionized water and ethanol. Finally, the sample was dried overnight in a vacuum oven at 60 °C to obtain the sample with molten sodium nitrate-induced SMSI construction.

[0061] (4) In this embodiment, the titanium dioxide supported iridium nanoclusters catalyst obtained by molten sodium nitrate-induced construction of SMSI were characterized by transmission electron microscopy (TEM), CO-DRIFTS, energy scattering X-ray spectroscopy (EDS), and extended X-ray absorption fine structure spectroscopy (EXAFS).

[0062] like Figure 1 As shown, the iridium nanoclusters supported on titanium dioxide exhibit significant disorder, with an average size of approximately 1.5 nm.

[0063] like Figure 2 As shown, the sample treated with molten sodium nitrate did not exhibit the characteristic peak of iridium adsorption for CO, indicating that the catalyst lost its ability to adsorb CO and strong metal-support interaction occurred.

[0064] Figure 3The EXAFS wavelet transform results showed obvious iridium-titanium coordination, indicating the occurrence of strong metal-carrier interaction.

[0065] In an environment of 350 °C, molten sodium nitrate successfully induced the formation of SMSI in a titanium dioxide-supported iridium cluster catalyst. The formation of iridium-titanium bonds led to a decrease in the d-band center of metallic iridium, resulting in a weakened adsorption capacity for hydrogen species by metallic iridium. Compared to the titanium dioxide-supported iridium cluster catalyst without SMSI formation, the hydrogen evolution reaction in a 0.5 M H₂SO₄ environment showed a faster reaction rate of 10 mA / cm². 2 The overpotential decreased from 156mV to 26mV, and the Tafel slope decreased from 68mV / dec to 31mV / dec.

[0066] Comparative Example 1

[0067] SMSI was constructed on titanium dioxide-supported iridium nanoclusters using hydrogen reduction at 350, 425 °C and 500 °C.

[0068] like Figure 4 As shown in the diffuse reflectance infrared spectrum of CO adsorption after high-temperature hydrogen reduction treatment, the CO adsorption peak of metallic iridium still exists.

[0069] Example 2

[0070] A method for constructing SMSI on a titanium dioxide-supported platinum nanoparticle catalyst induced by molten sodium nitrate: This embodiment is basically the same as the method in Example 1, except that the supported catalyst is titanium dioxide-supported platinum nanoparticles.

[0071] (1) The titanium dioxide carrier in this embodiment is commercial rutile titanium dioxide nanoparticles.

[0072] (2) Preparation method of titanium dioxide supported platinum nanoparticle catalyst:

[0073] First, 40 mg of titanium dioxide was dispersed in 20 mL of deionized water and sonicated to ensure uniform dispersion. Then, under magnetic stirring, 40 μL of a 0.1 mol / L tetraammonium nitrate platinum aqueous solution was gradually added dropwise, followed by drying the solution in a 60°C water bath. The resulting powder was thoroughly ground and placed in a muffle furnace, heated to 200°C at a rate of 10°C / min, and calcined in air for 5 hours. After cooling to room temperature, it was then calcined at 700°C for 1 hour in an argon-atmosphere tube furnace. The titanium dioxide-supported platinum nanoparticle catalyst was obtained upon cooling to room temperature.

[0074] (3) The method of constructing SMSI by inducing with molten metal sodium nitrate in this embodiment is the same as that in Example 1.

[0075] (4) In this embodiment, the titanium dioxide-supported platinum nanoparticle catalyst obtained by molten sodium nitrate-induced construction of SMSI was characterized by transmission electron microscopy (TEM).

[0076] like Figure 5 As shown, an amorphous coating layer is clearly visible on the surface of the platinum nanoparticles supported by titanium dioxide, and the average size of the platinum nanoparticles is about 10 nm.

[0077] Comparative Example 2

[0078] SMSI was constructed on a titanium dioxide-supported platinum nanoparticle catalyst by high-temperature reduction with a hydrogen-argon mixture at 350℃, 500℃, and 700℃.

[0079] like Figure 6 As shown, no amorphous coating layer appeared on the titanium dioxide platinum nanoparticles after high-temperature hydrogen and argon reduction at 350℃. However, thinner amorphous coating layers appeared after high-temperature hydrogen and argon treatment at 500℃ and 700℃. This indicates that the traditional gas-phase reduction method cannot induce the construction of SMSI of titanium dioxide-supported platinum nanoparticle catalysts at lower temperatures.

[0080] Example 3

[0081] A method for constructing SMSI on titanium dioxide-supported platinum nanoparticle catalysts induced by molten sodium tetrachloroaluminate:

[0082] (1) The preparation method of the titanium dioxide-supported platinum nanoparticle catalyst in this embodiment is the same as that in Example 2.

[0083] (2) Method for inducing the construction of SMSI by molten sodium tetrachloroaluminate:

[0084] The 20 mg titanium dioxide-supported platinum nanoparticle catalyst obtained in step (1) was thoroughly covered with 3 g sodium tetrachloroaluminate powder (melting point: 185 °C). The mixture was then heated to 200 °C or 350 °C at a rate of 5 °C / min and held for 30 min in a tube furnace under argon atmosphere. After cooling to room temperature, the calcined mixed solid was washed three times each with deionized water and ethanol. Finally, the sample was dried overnight in a vacuum oven at 60 °C to obtain the sample with molten sodium tetrachloroaluminate-induced SMSI construction.

[0085] like Figure 7 As shown, an amorphous coating layer is clearly visible on the surface of the platinum nanoparticles supported by titanium dioxide.

[0086] Example 4

[0087] A method for constructing SMSI on cerium dioxide-supported iridium nanoclusters induced by molten sodium nitrate:

[0088] (1) Preparation method of cerium dioxide support:

[0089] First, 2.5 mmol of cerium acetate was dissolved in 35 mL of deionized water, and 7.7 g of sodium hydroxide was added. The mixture was stirred at room temperature for 30 min and then transferred to a 50 mL Teflon-lined stainless steel autoclave. The autoclave was then incubated at 130 °C for 5 hours in a forced-air drying oven. The resulting sample was washed three times with deionized water and three times with ethanol, and then dried in a vacuum drying oven at 60 °C for 12 hours to obtain the cerium dioxide support.

[0090] (2) Preparation method of iridium nanocluster catalyst supported on cerium dioxide:

[0091] First, 40 mg of acetylacetone iridium precursor was mixed with 100 mg of pre-prepared cerium dioxide support in a mortar, and an appropriate amount of ethanol was added before thorough grinding. The mixed powder was placed in a tube furnace saturated with a 10% hydrogen-argon mixture and heated to 300 °C at a rate of 5 °C / min, and held at that temperature for 60 min to obtain cerium dioxide-supported iridium nanoclusters catalyst.

[0092] (3) The method for inducing the construction of SMSI with molten sodium nitrate is the same as in Example 1.

[0093] like Figure 8 As shown, the sample treated with molten sodium nitrate did not exhibit the characteristic peak of iridium adsorption for CO, indicating that the catalyst lost its ability to adsorb CO and strong metal-support interaction occurred.

[0094] Figure 9 The EXAFS wavelet transform results showed obvious iridium-cerium coordination, indicating the occurrence of strong metal-carrier interaction.

[0095] Example 5

[0096] A method for constructing SMSI on tin dioxide-supported iridium nanoclusters induced by molten sodium nitrate:

[0097] (1) Preparation method of tin dioxide support:

[0098] First, 0.677 g of tin dichloride dihydrate, 0.57 g of sodium hydroxide, and 3.5 g of polyvinylpyrrolidone were dissolved in 30 mL of deionized water. The mixture was stirred at room temperature for 30 min and then transferred to a 50 mL Teflon-lined stainless steel autoclave. The autoclave was then heated to 160 °C for 1.5 h in a forced-air drying oven. The resulting sample was washed three times with deionized water and three times with ethanol, and then dried in a vacuum drying oven at 60 °C for 12 h to obtain the tin dioxide support.

[0099] (2) Preparation method of iridium nanocluster catalyst supported on tin dioxide:

[0100] First, 40 mg of iridium acetylacetone precursor was mixed with 100 mg of pre-prepared tin dioxide support in a mortar, and an appropriate amount of ethanol was added before thorough grinding. The mixed powder was placed in a tube furnace saturated with a 10% hydrogen-argon mixture and heated to 300 °C at a rate of 5 °C / min, and held at that temperature for 60 min to obtain tin dioxide-supported iridium nanoclusters catalyst.

[0101] (3) The method for inducing the construction of SMSI with molten sodium nitrate is the same as in Example 1.

[0102] like Figure 10 As shown, the sample treated with molten sodium nitrate did not exhibit the characteristic peak of iridium adsorption for CO, indicating that the catalyst lost its ability to adsorb CO and strong metal-support interaction occurred.

[0103] Figure 11 The EXAFS wavelet transform results show obvious iridium-tin coordination, indicating the occurrence of strong metal-carrier interaction.

[0104] Example 6

[0105] A method for constructing SMSI on an alumina-supported gold cluster catalyst induced by molten potassium nitrate:

[0106] (1) Preparation method of alumina-supported gold cluster catalyst:

[0107] First, 40 mg of alumina was dispersed in 20 mL of deionized water and ultrasonically treated to ensure uniform dispersion. Then, under magnetic stirring, 5 μL of a 0.1 mol / L chloroauric acid aqueous solution was gradually added dropwise, followed by drying the solution in a 60 °C water bath. The resulting powder was thoroughly ground and placed in a muffle furnace, calcined at 300 °C at a heating rate of 10 °C / min in a hydrogen-argon mixture with a hydrogen integral of 10% for 60 min. After cooling to room temperature, the alumina-supported gold cluster catalyst was obtained.

[0108] (2) Method for constructing SMSI by induction with molten potassium nitrate:

[0109] A gold cluster catalyst supported on 20 mg of alumina was thoroughly covered with 3 g of potassium nitrate and calcined in a tube furnace at a heating rate of 5 °C / min to 500 °C for 30 min under argon atmosphere. After cooling to room temperature, the resulting mixed solid was washed three times each with deionized water and ethanol. Finally, the sample was dried overnight in a vacuum oven at 60 °C to obtain the sample with molten potassium nitrate-induced SMSI construction.

[0110] An amorphous coating layer was clearly observed on the surface of gold nanoclusters supported on alumina constructed with molten potassium nitrate at 500℃, indicating that molten potassium nitrate can successfully induce strong metal-support interactions in non-reducing support systems.

[0111] Example 7

[0112] A method for constructing SMSI on silica-supported palladium nanoparticle catalysts induced by molten potassium thiocyanate:

[0113] (1) Preparation method of palladium nanoparticle catalyst supported on silica:

[0114] First, 40 mg of silica was dispersed in 20 mL of deionized water and sonicated to ensure uniform dispersion. Then, under magnetic stirring, 60 μL of a 0.1 mol / L potassium chloropalladate aqueous solution was gradually added dropwise, followed by drying the solution in a 60 °C water bath. The resulting powder was thoroughly ground and placed in a muffle furnace, calcined at 300 °C at a heating rate of 10 °C / min in a hydrogen-argon mixture with a hydrogen integral of 10% for 1 h. After cooling to room temperature, the silica-supported palladium nanoparticle catalyst was obtained.

[0115] (2) Method for constructing SMSI by induction with molten potassium thiocyanate:

[0116] 20 mg of silica-supported gold nanoparticle catalyst was thoroughly covered with 5 g of potassium thiocyanate and calcined in a tube furnace at a heating rate of 10 °C / min to 200 °C for 1 h under argon atmosphere. After cooling to room temperature, the resulting mixed solid was washed three times each with large amounts of deionized water and ethanol. Finally, the sample was dried overnight in a vacuum oven at 60 °C to obtain the sample with molten potassium thiocyanate-induced SMSI construction.

[0117] At 200℃, palladium nanoparticles supported on silica constructed from molten potassium thiocyanate showed a significant loss of CO adsorption capacity and an obvious amorphous coating layer appeared on the surface. This surface, at a relatively low temperature of 200℃, showed that molten potassium thiocyanate could successfully induce strong metal-support interactions in the non-reducing support system.

[0118] Example 8

[0119] A method for constructing SMSI on a niobium pentoxide-supported ruthenium single-atom catalyst induced by molten magnesium chloride:

[0120] (1) Preparation method of ruthenium single-atom catalyst supported on niobium pentoxide:

[0121] First, 40 mg of niobium pentoxide was dispersed in 20 mL of deionized water and sonicated to ensure uniform dispersion. Then, under magnetic stirring, 2 μL of a 0.1 mol / L ruthenium chloride aqueous solution was gradually added dropwise, followed by drying the solution in a 60 °C water bath. The resulting powder was thoroughly ground and placed in a muffle furnace, calcined at 300 °C for 1 h in a hydrogen-argon mixture with a hydrogen integral of 10%. After cooling to room temperature, a niobium pentoxide-supported ruthenium single-atom catalyst was obtained.

[0122] (2) Method for inducing the construction of SMSI by molten magnesium chloride:

[0123] A 20 mg niobium pentoxide-supported ruthenium single-atom catalyst was thoroughly covered with 5 g magnesium chloride powder and calcined in a tube furnace under argon atmosphere at a heating rate of 5 °C / min to different temperatures (800-1000 °C) for 30 min. After cooling to room temperature, the resulting mixed solid was washed three times each with deionized water and ethanol. Finally, the sample was dried overnight in a vacuum oven at 60 °C to obtain the sample with molten magnesium chloride-induced SMSI.

[0124] In a high-temperature environment of 800-1000℃, the catalyst constructed from molten magnesium chloride completely lost its ability to adsorb small CO molecules and showed obvious ruthenium-magnesium bonds, without any obvious single-atom sintering phenomenon.

[0125] Example 9

[0126] A method for constructing MSI on zinc oxide-supported copper nanoparticle catalysts induced by molten sodium tetrachloroaluminate:

[0127] (1) First, 40 mg of zinc oxide was dispersed in 20 mL of deionized water and ultrasonically treated to ensure uniform dispersion. Then, under magnetic stirring, 60 μL of 0.2 mol / L copper nitrate aqueous solution was gradually added dropwise, followed by stirring the solution to dryness in a 60 °C water bath. The resulting powder was thoroughly ground and placed in a muffle furnace, heated to 400 °C at a heating rate of 10 °C / min, and calcined in a hydrogen-argon mixture with a hydrogen gas fraction of 10% for 3 h. After cooling to room temperature, the zinc oxide-supported copper nanoparticle catalyst was obtained.

[0128] (2) The 20 mg zinc oxide-supported copper nanoparticle catalyst obtained in step (1) was fully covered with 3 g sodium tetrachloroaluminate powder (melting point: 185 °C). The mixture was then heated to 500 °C at a rate of 5 °C / min and held for 30 min in a tube furnace under argon atmosphere. After cooling to room temperature, the calcined mixed solid was washed three times each with deionized water and ethanol. Finally, the sample was dried overnight in a vacuum oven at 60 °C to obtain the sample after molten sodium tetrachloroaluminate-induced SMSI construction.

[0129] In a high-temperature environment of 500℃, molten sodium tetrachloroaluminate successfully induced the formation of SMSI (Superimposed Simulated Silicity) on zinc oxide-supported copper nanoparticle catalysts. An amorphous zinc oxide coating appeared on the surface of the copper nanoparticles, which stabilized the copper nanoparticles and prevented their migration during carbon dioxide reduction. Therefore, in the electrocatalytic carbon dioxide reduction reaction, the amorphous coating on the surface of the copper nanoparticles can effectively increase the catalyst's stability. Compared with the catalyst without SMSI formation using molten sodium tetrachloroaluminate, the deactivation rate of active sites after 50 hours of catalytic carbon dioxide reduction decreased from 70% to 5.6%.

[0130] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for constructing a supported metal catalyst using molten salt-induced strong metal-support interactions, characterized in that, Includes the following steps: Supported metal catalysts are synthesized by a wet chemical method, wherein the supported metal catalysts include oxide supports and metal nanoparticles, clusters or single atoms; After the supported metal catalyst is fully covered with metal salt powder, it is heated to above the melting point of the metal salt under an inert atmosphere to melt the metal salt powder, and the temperature is maintained for 0.1~2 h. After cooling to room temperature, it is washed, centrifuged and dried in sequence to obtain the supported metal catalyst with strong metal-support interaction induced by molten salt. The mass ratio of the supported metal catalyst to the metal salt powder is 3~10 mg: 1 g; The oxide support includes one or more of titanium dioxide, cerium dioxide, tin dioxide, aluminum oxide, silicon dioxide, niobium pentoxide, or zinc oxide; The metal in the metal nanoparticles, clusters, or single atoms includes one or more of platinum, iridium, gold, palladium, ruthenium, rhodium, osmium, copper, silver, iron, cobalt, or nickel; The metal salt includes one or more of the following: lithium, sodium, potassium nitrates, tetrachloroaluminates, or chlorides.

2. The method as described in claim 1, characterized in that, The supported metal catalyst contains 0.01 to 60 wt% metal nanoparticles, clusters, or single atoms.

3. The method as described in claim 1, characterized in that, The inert atmosphere is argon or nitrogen; the heating rate is 4~10℃ / min.

4. The method as described in claim 1, characterized in that, The specific washing steps are as follows: wash with water and ethanol 2 to 4 times in sequence; the drying temperature is 40 to 100°C and the drying time is 2 to 20 hours.

5. The supported metal catalyst prepared by the method according to any one of claims 1 to 4 after molten salt-induced construction of strong metal-support interaction.

6. The application of the supported metal catalyst with strong metal-support interaction induced by molten salt as described in claim 5, characterized in that, The applications include using the supported metal catalysts formed by the molten salt-induced strong metal-support interaction as catalysts for hydrogen evolution reaction, oxygen evolution reaction, hydrogen oxidation reaction, oxygen reduction reaction, carbon dioxide reduction reaction, methane oxidation or formic acid oxidation reaction.

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