High-entropy perovskite catalytic material and preparation method and application thereof

Abstract

The invention discloses a high-entropy perovskite catalytic material and a preparation method and application thereof, and belongs to the technical field of catalysts.The preparation method comprises the steps that soluble La < 3 + > salt, soluble Co < 2 + > salt, soluble Cu < 2 + > salt, soluble Fe < 3 + > salt, soluble Mn < 2 + > salt and a soluble X ion source (X is Ga, Zn or Zr) serve as raw materials, a complexing agent and water are added to form a mixed solution, a head product is obtained through a solution combustion method, and the high-entropy perovskite catalytic material is obtained through calcination. The chemical formula of the high-entropy perovskite catalytic material is La (CoaCubFecMndXe) O3. The high-entropy perovskite catalytic material provided by the invention has excellent thermal stability, and can still keep good catalytic activity and excellent catalytic stability at high temperature. When the high-entropy perovskite catalytic material prepared by the method is used as a catalyst for CO2 hydrogenation to prepare ethanol, the high-entropy perovskite catalytic material has excellent ethanol selectivity.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a high-entropy perovskite catalytic material, its preparation method, and its application. Background Technology

[0002] The excessive consumption of fossil fuels has led to the massive release of greenhouse carbon dioxide, causing increasingly serious environmental problems such as ocean acidification and global climate change. Among various strategies for reducing carbon dioxide emissions, the catalytic conversion of carbon dioxide into useful chemicals, such as light olefins, alcohols, and oxygenated compounds, is highly attractive. Compared to methanol, ethanol shows broader industrial applications as a fuel additive and an indispensable high-energy-density engine fuel. Catalysts for the hydrogenation of carbon dioxide to ethanol play a crucial role in this process. The performance of the catalyst directly affects the conversion rate and selectivity of the reaction; therefore, developing efficient and stable catalysts is key to achieving industrial-scale production.

[0003] CO2 is an inert molecule, and its hydrogenation products are typically CO and methane, while alcohols are not thermodynamically favorable products. Furthermore, compared to methanol, the reaction pathway for ethanol formation is more complex, involving C / C bond coupling and prone to side reactions such as over-hydrogenation to methane, making it difficult to achieve high selectivity for ethanol. Current catalytic systems used for the catalytic hydrogenation of CO2 to ethanol mainly include noble metal catalysts, such as Ru and Pd-based catalysts, and Fischer-Tropsch synthesis catalysts, such as Fe-based catalysts. While these catalysts can achieve CO2 hydrogenation to some extent, they all have significant drawbacks: noble metal catalysts are expensive and difficult to apply on a large scale; Fischer-Tropsch synthesis Fe-based catalysts have complex compositions, often forming multiple phases such as Fe5C2, Fe2C, Fe3C, Fe3O4, and elemental Fe after reaction induction, resulting in a wide product distribution, with ethanol selectivity typically below 20%, and poor catalyst thermal stability, making them prone to deactivation during the reaction. Summary of the Invention

[0004] This invention provides a high-entropy perovskite catalytic material, its preparation method, and its application, aiming to solve the technical problems of existing catalysts used for catalytic CO2 hydrogenation to ethanol production, such as high cost, low ethanol selectivity, poor thermal stability, and easy deactivation. This invention obtains a high-entropy perovskite catalytic material with the chemical formula La(Co) via solution combustion. a Cu b Fe c Mn d X eThe present invention provides a high-entropy perovskite catalyst material of O3, wherein X is Ga, Zn or Zr; the synthesis method provided by the present invention is simple and the catalyst structure is stable. By changing the type of X and the content of different metal components, the efficient conversion of CO2 and the selective production of products can be achieved, providing a catalyst that can efficiently activate CO2, highly selectively promote the coupling of C-C bonds to generate ethanol, and has good stability.

[0005] The first objective of this invention is to provide a high-entropy perovskite catalytic material, wherein the chemical formula of the high-entropy perovskite catalytic material is La(Co) a Cu b Fe c Mn d X e O3, where X is Ga, Zn or Zr; a, b, c, d, e are the number of moles of atoms.

[0006] The high-entropy perovskite catalyst material is based on soluble La 3+ Salt, soluble Co 2+ Salt, soluble Cu 2+ Salt, soluble Fe 3+ Salt, soluble Mn 2+ Salt and soluble X ion source are used as raw materials. A complexing agent and water are added to form a mixture. The primary product is obtained by solution combustion and then calcined.

[0007] The soluble La 3+ Salt, soluble Co 2+ Salt, soluble Cu 2+ Salt, soluble Fe 3+ Salt, soluble Mn 2+ The molar ratio of salt to soluble X ion source is 1:0.1~0.5:0.1~0.5:0.1~0.5:0.1~0.5:0.1~0.5.

[0008] As a preferred embodiment, the soluble La 3+ The molar ratio of salt to complexing agent is 1:0.01 to 0.5.

[0009] In a preferred embodiment, a fuel agent is also added to the mixture, wherein the soluble La 3+ The molar ratio of salt to fuel agent is 1:1 to 3.

[0010] In a preferred embodiment, fuel, specifically glycine, is also added. This invention uses glycine as a fuel agent. During the combustion reaction, the fuel agent decomposes and releases a large amount of heat energy, causing the metal salt to decompose into metal oxides. The oxidation-reduction process between the metal salt and glycine at high temperatures during combustion decomposes the metal salt into the target metal oxide. The gases (CO2, H2O, N2) released instantaneously during combustion cause the product to form a fluffy black powder, thereby exposing more active sites and improving the catalytic performance of CO2 hydrogenation to ethanol.

[0011] In a preferred embodiment, the complexing agent is citric acid. The complexing agent citric acid can react with metal ions (such as La2+). 3+ Co 2+ Cu 2+ (etc.) Forming stable complexes enhances the solubility of metal salts in solution, ensuring uniform mixing of components and avoiding local precipitation. By complexing metal ions, the complexing agent can regulate the chemical environment of the precursor solution, affecting the rate and temperature of the combustion reaction, making the reaction process more controllable, and avoiding uneven product structure caused by excessively fast or slow reactions.

[0012] A second objective of this invention is to provide a method for preparing the high-entropy perovskite catalytic material described above, comprising the following steps: With soluble La 3+ Salt, soluble Co 2+ Salt, soluble Cu 2+ Salt, soluble Fe 3+ Salt, soluble Mn 2+ Salt and soluble X ion source are used as raw materials. A complexing agent and water are added to obtain a mixture. The water is removed to obtain a gel-like substance.

[0013] The gel-like substance is heated to 250℃~350℃, causing a combustion reaction that converts the metal compounds in the gel-like substance into metal oxides. At the same time, gas is released to form active sites, yielding the primary product.

[0014] The primary product is heated and calcined to crystallize it, thereby obtaining a high-entropy perovskite catalytic material.

[0015] In the above preparation process, a fuel agent is also added. The metal salt, complexing agent, and fuel agent are mixed in solution, and a uniform precursor gel is formed through complexation to avoid metal ion precipitation. During the combustion reaction, the fuel agent decomposes and releases a large amount of heat energy, causing the metal salt to decompose into metal oxides. The combustion reaction is a redox process that occurs between the metal salt and the fuel agent at high temperature, decomposing the metal salt into the target metal oxide. The gases (CO2, H2O, N2) released instantaneously during combustion cause the product to form a fluffy black powder, thereby exposing more active sites and improving the catalytic performance of CO2 hydrogenation to ethanol. The initial product obtained after the combustion reaction is calcined and further crystallized to form a stable perovskite-type high-entropy metal oxide, i.e., a high-entropy perovskite catalytic material. During the calcination process, residual organic fuel agents or incompletely reacted intermediate products are decomposed, thereby improving the purity of the material and enhancing the activity and stability of the catalyst.

[0016] The general formula for the reaction of the fuel agent glycine (C2H5NO2) with metal nitrates under heating conditions is as follows: ; Where M is a metallic element, namely La, Co, Cu, Fe, Mn, Ga, Zn, and Zr; v The valence of a metal cation; φ The molar ratio of fuel to oxygen is preferably 1 to 1.1:1.

[0017] In a preferred embodiment, the heating and calcination is carried out by heating to 800℃~1000℃ at a rate of 2℃ / min and calcining for 8 hours.

[0018] As a preferred embodiment, the soluble La 3+ The ratio of salt to water is 1 mol: 250 mL.

[0019] As a preferred embodiment, the soluble La 3+ The salt is La(NO3)3·6H2O, and the soluble Co... 2+ The salt is Co(NO3)2·6H2O, and the soluble Cu is... 2+ The salt is Cu(NO3)2·3H2O, and the soluble Fe is... 3+ The salt is Fe(NO3)3·9H2O, and the soluble Mn is... 2+ The salt is Mn(NO3)2·4H2O, and the soluble X ion source is selected from Ga(NO3)3·9H2O, Zn(NO3)2·6H2O or Zr(NO3)4·5H2O.

[0020] The third objective of this invention is to provide an application of the high-entropy perovskite catalyst described in any one of the above claims as a catalyst in the hydrogenation of CO2 to ethanol. The application includes the following steps: granulating the high-entropy perovskite catalyst to obtain a catalyst; performing a reduction pretreatment on the catalyst at 300°C in an H2 atmosphere; cooling the catalyst to 280°C; introducing a mixed reaction gas of H2:CO2 and N2 with a volume ratio of 72:24:4; and carrying out the CO2 hydrogenation to ethanol reaction at a pressure of 3 MPa.

[0021] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a high-entropy perovskite catalytic material, using soluble La 3+ Salt, soluble Co 2+ Salt, soluble Cu 2+ Salt, soluble Fe 3+ Salt, soluble Mn 2+ Using salt and a soluble X ion source (X being Ga, Zn, or Zr) as raw materials, a complexing agent and water are added to form a mixture. The initial product is obtained through solution combustion, followed by calcination to obtain the product with the chemical formula La(Co). a Cu b Fe c Mn d X e High-entropy perovskite catalytic materials of O3.

[0022] This invention achieves efficient CO2 conversion and selective product yield by altering the type of metal ion X and the content of different metal components. The ionic radius of metal ion X (Ga) 3+ Zn 2+ Zr 4+ ) and other metal ions at the B-site of high-entropy perovskite catalysts (Co) 2+ Cu 2+ Fe 3+ Mn 2+ Differences in the concentration of X metal ions introduce lattice distortion, which enhances the stability of the crystal structure through a high-entropy effect. Furthermore, due to the high electronegativity of the X metal ion, it can lower the d-band center, thereby reducing excessive CO2 hydrogenation and promoting C / C coupling, resulting in better ethanol selectivity. The X metal element is uniformly distributed in the perovskite, forming synergistic active sites with other B-site ions, promoting CH4 coupling during CO2 hydrogenation. x The intermediate is coupled to form ethanol, rather than undergoing excessive hydrogenation to form CH4. Therefore, the high-entropy perovskite catalyst provided by this invention exhibits excellent thermal stability and maintains good catalytic activity at high temperatures. Using the high-entropy perovskite catalyst prepared by this invention as a catalyst for the CO2 hydrogenation to ethanol reaction demonstrates excellent ethanol selectivity.

[0023] The high-entropy perovskite catalytic material provided by this invention has a stable structure, a simple synthesis method, and is suitable for industrial production. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 The XRD patterns of the high-entropy perovskite catalytic materials prepared in Examples 1 and 2 of this invention are shown.

[0026] Figure 2 The XRD patterns are those of the catalysts prepared in Comparative Examples 1 to 3 of this invention.

[0027] Figure 3 The XRD patterns of the high-entropy perovskite catalyst prepared in Example 1 of this invention before and after 12 hours of CO2 hydrogenation to ethanol reaction are compared.

[0028] Figure 4 The images shown are SEM images and surface scan energy dispersive spectroscopy (SSD) spectra of the high-entropy perovskite catalytic material prepared in Example 1 of this invention. In the images shown, (a) is an SEM image, (b) shows the elemental content, (c) shows the La elemental distribution, (d) shows the Co elemental distribution, (e) shows the Cu elemental distribution, (f) shows the Fe elemental distribution, (g) shows the Mn elemental distribution, and (h) shows the Ga elemental distribution.

[0029] Figure 5 These are TEM images of the high-entropy perovskite catalytic material prepared in Example 1 of this invention, wherein (a) is a LaGaO3 lattice stripe in one region, (b) is a LaGaO3 lattice stripe in another region, (c) is a LaCoO3 lattice stripe, (d) is a LaCu2O4 lattice stripe, and (e) is a La... 0.88 MnO 2.92 Lattice fringes, (f) are LaFeO3 lattice fringes. Detailed Implementation

[0030] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0031] Existing catalysts for the hydrogenation of carbon dioxide to ethanol suffer from several drawbacks. First, noble metal catalysts, such as Ru and Pd-based catalysts, are expensive and difficult to apply on a large scale. Second, Fischer-Tropsch synthesis catalysts, such as Fe-based catalysts, have complex compositions. After reaction induction, these catalysts typically form multiple phases, including Fe5C2, Fe2C, Fe3C, Fe3O4, and elemental Fe, resulting in a wide product distribution, ethanol selectivity usually below 20%, and poor thermal stability, making them prone to deactivation during the reaction. Based on these technical problems, this invention provides a high-entropy perovskite catalytic material, its preparation method, and its applications.

[0032] In recent years, high-entropy oxides have been considered as potential candidates for novel functional materials. High-entropy oxides typically consist of five or more metal oxides, forming a single-phase solid solution with randomly occupied sites. Due to the high-entropy effect, premixes of multi-component oxides primarily transform into single-phase crystal structures such as perovskite, spinel, or rock salt, rather than forming multi-component intermetallic phases. Benefiting from an ideal maximum doping model, high-entropy oxides exhibit better structural stability than single-metal oxides and multiple intermetallic oxides, and their unique properties hold great promise for solving problems present in ordinary composite metal oxides. Among the many high-entropy oxides, those with a stable perovskite (ABO3) structure have attracted significant attention.

[0033] However, the difficulty in preparing high-entropy metal oxide catalysts suitable for the hydrogenation of carbon dioxide to ethanol lies mainly in the following aspects: the complexity of material design, as high-entropy metal oxide catalysts typically contain multiple metal elements, and the proportion, distribution, and interactions between these elements significantly affect the catalyst's performance. Designing such catalysts requires precise control of composition and structure to achieve optimal catalytic activity and stability; the challenge of synthesis methods, as the synthesis of high-entropy metal oxide catalysts requires special high-temperature, high-pressure, or atmospheric conditions, which are difficult to control and affect the catalyst's microstructure and surface properties. Furthermore, the uniformity and purity during the synthesis process are also challenges; and the optimization of catalytic performance, even if a high-entropy metal oxide catalyst is successfully synthesized, ensuring its high activity, high selectivity, and high stability is a complex engineering process. This requires precise control over the catalyst's surface chemistry, acidic centers, and electronic structure. Therefore, developing a novel catalyst that can efficiently activate CO2, highly selectively promote C-C bond coupling to ethanol, and possess good stability is key to overcoming the current bottlenecks in CO2 hydrogenation to ethanol technology.

[0034] The technical solution of the present invention will be described below.

[0035] This invention provides a high-entropy perovskite catalytic material, wherein the chemical formula of the high-entropy perovskite catalytic material is La(Co).a Cu b Fe c Mn d X e O3, where X is Ga, Zn or Zr; a, b, c, d, e are the number of moles of atoms.

[0036] The high-entropy perovskite catalyst material is based on soluble La 3+ Salt, soluble Co 2+ Salt, soluble Cu 2+ Salt, soluble Fe 3+ Salt, soluble Mn 2+ Salt and soluble X ion source are used as raw materials. A complexing agent and water are added to form a mixture. The primary product is obtained by solution combustion and then calcined.

[0037] The soluble La 3+ Salt, soluble Co 2+ Salt, soluble Cu 2+ Salt, soluble Fe 3+ Salt, soluble Mn 2+ The molar ratio of salt to soluble X ion source is 1:0.1~0.5:0.1~0.5:0.1~0.5:0.1~0.5:0.1~0.5.

[0038] The high-entropy perovskite catalytic material provided above, due to the ionic radius of the X metal ion (Ga 3+ Zn 2+ Zr 4+ ) and other metal ions at the B-site of high-entropy perovskite catalysts (Co) 2+ Cu 2+ Fe 3+ Mn 2+ Differences in the concentration of carbon dioxide (C₂, C₂, and C₃) introduce lattice distortion, which enhances the stability of the crystal structure through a high-entropy effect. Because the X metal ion has high electronegativity, it can lower the d-band center, thereby reducing excessive CO₂ hydrogenation and promoting C₂C₃ coupling, resulting in better ethanol selectivity. The X metal element is uniformly distributed in the perovskite, forming synergistic active sites with other B-site ions, promoting CH₄ coupling during CO₂ hydrogenation. x The intermediate is coupled to form ethanol, rather than undergoing excessive hydrogenation to form CH4. Therefore, the high-entropy perovskite catalyst provided by this invention exhibits excellent thermal stability and maintains good catalytic activity at high temperatures. Using the high-entropy perovskite catalyst prepared by this invention as a catalyst for the CO2 hydrogenation to ethanol reaction demonstrates excellent ethanol selectivity.

[0039] The technical effects of the present invention will be described below through specific embodiments and comparative examples.

[0040] Example 1 A high-entropy perovskite catalyst with the chemical formula LaCo 0.2 Cu 0.2 Fe 0.2 Mn 0.2 Ga 0.2 O3.

[0041] The preparation method of the above-mentioned high-entropy perovskite catalytic material includes the following steps: S1. Dissolve 1 mol of La(NO3)3·6H2O, 0.2 mol of Co(NO3)2·6H2O, 0.2 mol of Cu(NO3)2·3H2O, 0.2 mol of Fe(NO3)3·9H2O, 0.2 mol of Mn(NO3)2·4H2O, 0.2 mol of Ga(NO3)3·9H2O, 0.1 mol of citric acid, and 2 mol of glycine in 250 mL of deionized water and stir evenly at 40 °C to prepare a homogeneous mixture.

[0042] S2, the mixture is heated in an 85°C water bath with continuous stirring to evaporate excess water until the mixture transforms into a gel-like substance. The gel-like substance is transferred to a combustion vessel, and the temperature is raised to 300°C to induce a combustion reaction, yielding a black, fluffy blocky product.

[0043] S3, the bulk product is ground into powder and calcined in a muffle furnace at a rate of 2℃ / min to 900℃ for 8 hours to obtain a high-entropy perovskite catalyst material. This material is used as a catalyst for the CO2 hydrogenation to ethanol reaction.

[0044] Example 2 A high-entropy perovskite catalyst with the chemical formula LaCo 0.2 Cu 0.2 Fe 0.2 Mn 0.2 Ga 0.2 O3.

[0045] The preparation method of the above-mentioned high-entropy perovskite catalytic material includes the following steps: S1. Dissolve 1 mol of La(NO3)3·6H2O, 0.2 mol of Co(NO3)2·6H2O, 0.2 mol of Cu(NO3)2·3H2O, 0.2 mol of Fe(NO3)3·9H2O, 0.2 mol of Mn(NO3)2·4H2O, 0.2 mol of Ga(NO3)3·9H2O and 0.1 mol of citric acid in 250 mL of deionized water and stir evenly at 40 °C to prepare a homogeneous mixture.

[0046] S2, the mixture is heated in an 85°C water bath with continuous stirring to evaporate excess water until the mixture transforms into a gel-like substance. The gel-like substance is then transferred to a combustion vessel, and the temperature is raised to 300°C to induce a combustion reaction, yielding a black, fluffy blocky product.

[0047] S3. The bulk product is ground into powder and calcined in a muffle furnace at a rate of 2℃ / min to 900℃ for 8 hours to obtain a high-entropy perovskite catalyst material for use as a catalyst in the CO2 hydrogenation to ethanol reaction.

[0048] Example 3 A high-entropy perovskite catalyst with the chemical formula LaCo 0.2 Cu 0.2 Fe 0.2 Mn 0.2 Zn 0.2 O3.

[0049] The preparation method of the above-mentioned high-entropy perovskite catalytic material includes the following steps: S1. Dissolve 1 mol of La(NO3)3·6H2O, 0.2 mol of Co(NO3)2·6H2O, 0.2 mol of Cu(NO3)2·3H2O, 0.2 mol of Fe(NO3)3·9H2O, 0.2 mol of Mn(NO3)2·4H2O, 0.2 mol of Zn(NO3)2·6H2O, 0.1 mol of citric acid, and 2 mol of glycine in 250 mL of deionized water and stir evenly at 40 °C to prepare a homogeneous mixture.

[0050] S2, the mixture is heated in an 85°C water bath with continuous stirring to evaporate excess water until the mixture transforms into a gel-like substance. The gel-like substance is transferred to a combustion vessel, and the temperature is raised to 300°C to induce a combustion reaction, yielding a black, fluffy blocky product.

[0051] S3, the bulk product is ground into powder and calcined in a muffle furnace at a rate of 2℃ / min to 900℃ for 8 hours to obtain a high-entropy perovskite catalyst material. This material is used as a catalyst for the CO2 hydrogenation to ethanol reaction.

[0052] Example 4 A high-entropy perovskite catalyst with the chemical formula LaCo 0.2 Cu 0.2 Fe 0.2 Mn 0.2 Zr 0.2 O3.

[0053] The preparation method of the above-mentioned high-entropy perovskite catalytic material includes the following steps: S1. Dissolve 1 mol of La(NO3)3·6H2O, 0.2 mol of Co(NO3)2·6H2O, 0.2 mol of Cu(NO3)2·3H2O, 0.2 mol of Fe(NO3)3·9H2O, 0.2 mol of Mn(NO3)2·4H2O, 0.2 mol of Zr(NO3)4·5H2O, 0.1 mol of citric acid, and 2 mol of glycine in 250 mL of deionized water and stir evenly at 40 °C to prepare a homogeneous mixture.

[0054] S2, the mixture is heated in an 85°C water bath with continuous stirring to evaporate excess water until the mixture transforms into a gel-like substance. The gel-like substance is transferred to a combustion vessel, and the temperature is raised to 300°C to induce a combustion reaction, yielding a black, fluffy blocky product.

[0055] S3, the bulk product is ground into powder and calcined in a muffle furnace at a rate of 2℃ / min to 900℃ for 8 hours to obtain a high-entropy perovskite catalyst material. This material is used as a catalyst for the CO2 hydrogenation to ethanol reaction.

[0056] To further illustrate the technical effects of the present invention, a comparative example is also provided, as follows.

[0057] Comparative Example 1 Compared to Example 1, Ga(NO3)3·9H2O was not added.

[0058] A high-entropy perovskite catalyst with the chemical formula LaCo 0.25 Cu 0.25 Fe 0.25 Mn 0.25 O3.

[0059] The preparation method of the above-mentioned high-entropy perovskite catalytic material specifically includes the following steps: S1. Dissolve 1 mol of La(NO3)3·6H2O, 0.25 mol of Co(NO3)2·6H2O, 0.25 mol of Cu(NO3)2·3H2O, 0.25 mol of Fe(NO3)3·9H2O, 0.25 mol of Mn(NO3)2·4H2O, 0.1 mol of citric acid, and 2 mol of glycine in 250 mL of deionized water and stir evenly at 40 °C to prepare a homogeneous mixture.

[0060] S2, the mixture is heated in an 85°C water bath with continuous stirring to evaporate excess water until the mixture transforms into a gel-like substance. The gel-like substance is transferred to a combustion vessel, and the temperature is raised to 300°C to induce a combustion reaction, yielding a black, fluffy blocky product.

[0061] S3. The bulk product is ground into powder and calcined in a muffle furnace at a rate of 2℃ / min to 900℃ for 8 hours to obtain a high-entropy perovskite catalyst. This catalyst is used for the CO2 hydrogenation to ethanol reaction.

[0062] Comparative Example 2 Compared to Example 1, Mn(NO3)2·4H2O and Ga(NO3)3·9H2O were not added.

[0063] A perovskite catalyst with the chemical formula LaCo 0.2 Cu 0.2 Fe 0.2 O3.

[0064] The preparation method of the above perovskite catalytic material includes the following steps: S1. Dissolve 1 mol of La(NO3)3·6H2O, 0.2 mol of Co(NO3)2·6H2O, 0.2 mol of Cu(NO3)2·3H2O, 0.2 mol of Fe(NO3)3·9H2O, 0.1 mol of citric acid, and 2 mol of glycine in 250 mL of deionized water and stir evenly at 40 °C to prepare a homogeneous mixture.

[0065] S2, the mixture is heated in an 85°C water bath with continuous stirring to evaporate excess water until the mixture transforms into a gel-like substance. The gel-like substance is transferred to a combustion vessel, and the temperature is raised to 300°C to induce a combustion reaction, yielding a black, fluffy blocky product.

[0066] S3, the bulk product is ground into powder and calcined in a muffle furnace at a rate of 2℃ / min to 900℃ for 8 hours to obtain a perovskite catalyst material. This material is used as a catalyst for the CO2 hydrogenation to ethanol reaction.

[0067] Comparative Example 3 Compared to Example 1, Fe(NO3)3·9H2O and Ga(NO3)3·9H2O were not added.

[0068] A perovskite catalyst with the chemical formula LaCo 0.2 Cu 0.2 Mn 0.2 O3.

[0069] The preparation method of the above-mentioned perovskite catalytic material includes the following steps: S1. Dissolve 1 mol of La(NO3)3·6H2O, 0.2 mol of Co(NO3)2·6H2O, 0.2 mol of Cu(NO3)2·3H2O, 0.2 mol of Mn(NO3)2·4H2O, 0.1 mol of citric acid, and 2 mol of glycine in 250 mL of deionized water and stir evenly at 40 °C to prepare a homogeneous mixture.

[0070] S2, the mixture is heated in an 85°C water bath with continuous stirring to evaporate excess water until the mixture transforms into a gel-like substance. The gel-like substance is transferred to a combustion vessel, and the temperature is raised to 300°C to induce a combustion reaction, yielding a black, fluffy blocky product.

[0071] S3, the bulk product is ground into powder and calcined in a muffle furnace at a rate of 2℃ / min to 900℃ for 8 hours to obtain a perovskite catalyst material. This material is used as a catalyst for the CO2 hydrogenation to ethanol reaction.

[0072] The high-entropy perovskite catalysts prepared in the above examples and Comparative Example 1, as well as the perovskite catalysts prepared in Comparative Examples 2 and 3, were used as catalysts in the CO2 hydrogenation to ethanol reaction, as detailed below.

[0073] Experiments were conducted using a fixed-bed reactor under specific conditions of temperature, pressure, space velocity, and CO2 / H2 feed ratio to catalyze the hydrogenation of CO2 to ethanol using a high-entropy perovskite catalyst. The product distribution was analyzed using gas chromatography. The specific procedures are as follows: S1, the perovskite catalysts prepared in each example and comparative example are pressed into tablets at 10 MPa and then granulated to 20-40 mesh to obtain each catalyst.

[0074] S2, 0.5 g of catalyst was packed into a quartz tube, which was then placed into a fixed-bed reactor. The reactor was heated to 300 °C, and reduction pretreatment was carried out in an H2 atmosphere with an H2 space velocity of 2400 mL·g. cat -1 ·h -1 Restoration takes 6 hours.

[0075] S3, the reactor is cooled to 280℃, and a mixed reaction gas of H2, CO2 and N2 with a volume ratio of 72:24:4 is introduced, with a gas space velocity of 12000 mL·g. cat -1 ·h -1 The reaction pressure was increased to 3 MPa, and after the reaction proceeded for 12 hours, the reaction products were analyzed online using a gas chromatograph to calculate the CO2 conversion rate and product selectivity.

[0076] The results of the CO2 conversion rate and product selectivity are shown in Table 1.

[0077] Table 1. Performance of perovskite catalysts in the CO2 hydrogenation to ethanol production of the embodiments and comparative examples of the present invention. Table 1 shows that, comparing Example 1 and Example 2, although the addition of glycine slightly reduced the catalyst activity, it promoted ethanol production. Comparison of Example 1 with glycine and Example 2 without glycine: Ethanol selectivity: Example 1 (38.5%) > Example 2 (33.0%); Total alcohol selectivity: Example 1 (52.3%) > Example 2 (49.2%). Therefore, the addition of glycine further improves both total alcohol selectivity and ethanol selectivity. This indicates that glycine, by improving the pore structure of the high-entropy perovskite catalyst, is more conducive to the coupling of CC to produce ethanol, rather than side reactions (such as excessive hydrogenation to produce CH4). Comparing Example 1 with Comparative Examples 1-3 shows that the addition of metallic Ga is crucial for the catalytic hydrogenation of CO2 to ethanol, while the addition of Mn helps to suppress CH4 production.

[0078] Due to Ga 3+ (Example 1) High electronegativity can lower the d-band center, reduce excessive CO2 hydrogenation, and promote CC coupling, thus demonstrating the ethanol selectivity of 38.5% in Example 1; according to Ga... 3+ (Example 1) SEM surface scanning energy dispersive spectroscopy showed that Ga elements were uniformly distributed in the perovskite, forming synergistic active sites with other B-site ions, promoting CH in the CO2 hydrogenation process. x The intermediate is coupled to generate ethanol, rather than being over-hydrogenated to generate CH4. Therefore, the CH4 selectivity of Example 1 is 36.3%, which is much lower than that of Comparative Example 2 (67.6%). When the X ion is missing (Comparative Example 1), the product distribution is broad (ethanol selectivity is only 3.3%). Therefore, it is proven that the introduction of the X metal element in this invention is the key to controlling the selectivity.

[0079] The morphology, structure, and properties of the high-entropy perovskite catalytic materials prepared in the above embodiments and comparative examples were characterized, and the results are as follows.

[0080] Figure 1 The images show the XRD patterns of the high-entropy perovskite catalytic materials prepared in Examples 1 and 2 of this invention. Figure 1It can be seen that strong diffraction peaks are observed at 22.6°, 32.2°, 39.7°, 46.2°, 52.0°, 57.4°, 67.4°, 72.1°, and 76.7°, which are consistent with the diffraction peaks of LaFeO3 perovskite (PDF#75-0541) in the range of 20° to 80° in the standard PDF card. These peaks correspond to the reflections of the (100), (110), (111), (200), (210), (211), (220), (221), and (310) crystal planes, respectively, and belong to the perovskite crystal structure of the R-3c space group. This indicates that the material prepared by the present invention has a perovskite structure.

[0081] Figure 2 The images show the XRD patterns of the catalysts prepared in Comparative Examples 1 to 3 of this invention. Figure 2 It can be seen that the perovskite LaCo sample in Comparative Example 1 of this invention and the standard PDF card... 0.4 Fe 0.6 The consistent diffraction peaks of O3 (PDF#40-0224) within the 20° to 80° range indicate a perovskite crystal structure belonging to the R-3c space group, demonstrating that the material in Comparative Example 1 possesses a perovskite structure. While samples in Comparative Examples 2 and 3 exhibit diffraction peaks belonging to perovskite, they contain numerous impurity phases. Therefore, the addition of Fe and Mn is crucial for the formation of a stable perovskite structure.

[0082] like Figure 1 and Figure 2 As shown in the XRD pattern, the diffraction peaks of Example 1 (containing Ga) completely match the standard perovskite structure (LaFeO3, PDF#75-0541), while the comparative examples 2 to 3 (lacking X or Mn / Fe) show impurity peaks, proving that the X element helps to maintain a single perovskite phase.

[0083] Figure 3 The XRD patterns of the high-entropy perovskite catalyst prepared in Example 1 of this invention before and after 12 hours of CO2 hydrogenation to ethanol reaction are compared. Figure 3 It can be seen that the high-entropy perovskite catalyst material after the CO2 hydrogenation to ethanol reaction still maintains the LaFeO3 perovskite crystal structure, proving that the high-entropy perovskite catalyst material prepared in Example 1 has excellent catalytic stability.

[0084] Figure 4 These are SEM images and surface scan energy dispersive spectroscopy (SSD) spectra of the high-entropy perovskite catalytic material prepared in Example 1 of this invention. Figure 4It can be seen that the high-entropy perovskite catalytic material sample prepared in Example 1 contains various elements such as La, Co, Cu, Fe, Mn, and Ga, and these elements are evenly distributed in the sample. Combined with the perovskite structure confirmed by the XRD pattern, it indicates that the prepared sample is a high-entropy perovskite oxide LaCo. 0.2 Cu 0.2 Fe 0.2 Mn 0.2 Ga 0.2 O3.

[0085] Figure 5 These are TEM images and surface scan spectroscopy spectra of the high-entropy perovskite catalytic material prepared in Example 1 of this invention. Figure 5 As can be seen, the high-entropy perovskite catalyst prepared in Example 1 has clear particle boundaries, uniform size, and interconnected structure. By analyzing the lattice spacing, it was found that Co, Cu, Fe, Mn, and Ga in the prepared high-entropy perovskite catalyst form perovskite structures with La, namely LaCoO3, LaCuO3, LaFeO3, LaMnO3, and LaGaO3, respectively, which is completely consistent with the XRD characterization results.

[0086] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the inventive concept of the present invention, can make other changes and modifications to these embodiments, all of which fall within the scope of the present invention.

[0087] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention also intends to include these modifications and variations.

Claims

1. A high-entropy perovskite catalytic material, characterized in that, The chemical formula of the high-entropy perovskite catalyst is La(Co) a Cu b Fe c Mn d X e O3, where X is Ga, Zn, or Zr; a, b, c, d, and e are the number of moles of atoms; The high-entropy perovskite catalyst material is based on soluble La 3+ Salt, soluble Co 2+ Salt, soluble Cu 2+ Salt, soluble Fe 3+ Salt, soluble Mn 2+ Salt and soluble X ion source are used as raw materials. A complexing agent and water are added to form a mixture. The primary product is obtained by solution combustion and then calcined. The soluble La 3+ Salt, soluble Co 2+ Salt, soluble Cu 2+ Salt, soluble Fe 3+ Salt, soluble Mn 2+ The molar ratio of salt to soluble x-ion source is 1:0.1~0.5:0.1~0.5:0.1~0.5:0.1~0.5:0.1~0.

5.

2. The high-entropy perovskite catalytic material according to claim 1, characterized in that, The soluble La 3+ The molar ratio of salt to complexing agent is 1:0.01 to 0.

5.

3. The high-entropy perovskite catalytic material according to claim 1, characterized in that, The mixture also contains a fuel agent, namely soluble La. 3+ The molar ratio of salt to fuel agent is 1:1 to 3.

4. The high-entropy perovskite catalytic material according to claim 3, characterized in that, The fuel agent is glycine.

5. The high-entropy perovskite catalytic material according to claim 1, characterized in that, The complexing agent is citric acid.

6. A method for preparing the high-entropy perovskite catalytic material according to claim 1, characterized in that, Includes the following steps: With soluble La 3+ Salt, soluble Co 2+ Salt, soluble Cu 2+ Salt, soluble Fe 3+ Salt, soluble Mn 2+ Salt and soluble X ion source are used as raw materials. A complexing agent and water are added to obtain a mixture. The water is removed to obtain a gel-like substance. The gel-like substance is heated to 250℃~350℃, and a combustion reaction occurs, which converts the metal compounds in the gel-like substance into metal oxides. At the same time, gas is released to form active sites, and the initial product is obtained. The primary product is heated and calcined to crystallize it, thereby obtaining a high-entropy perovskite catalytic material.

7. The method for preparing the high-entropy perovskite catalytic material according to claim 6, characterized in that, The heating and calcination process involves raising the temperature to 800℃~1000℃ at a rate of 2℃ / min and calcining for 8 hours.

8. The method for preparing the high-entropy perovskite catalytic material according to claim 6, characterized in that, The soluble La 3 + The ratio of salt to water is 1 mol: 250 mL.

9. The method for preparing the high-entropy perovskite catalytic material according to claim 6, characterized in that, The soluble La 3 + The salt is La(NO3)3·6H2O, and the soluble Co... 2+ The salt is Co(NO3)2·6H2O, and the soluble Cu is... 2+ The salt is Cu(NO3)2·3H2O, and the soluble Fe is... 3+ The salt is Fe(NO3)3·9H2O, and the soluble Mn is... 2+ The salt is Mn(NO3)2·4H2O, and the soluble X ion source is selected from Ga(NO3)3·9H2O, Zn(NO3)2·6H2O or Zr(NO3)4·5H2O.

10. The application of the high-entropy perovskite catalyst according to any one of claims 1 to 5 as a catalyst in the hydrogenation of CO2 to ethanol, characterized in that, The application includes the following steps: granulating high-entropy perovskite catalyst to obtain a catalyst, subjecting the catalyst to reduction pretreatment at 300°C in an H2 atmosphere, cooling to 280°C, introducing a mixed reaction gas of H2:CO2 and N2 with a volume ratio of 72:24:4, and carrying out a CO2 hydrogenation to ethanol reaction at a pressure of 3MPa.

Images