Methane carbon dioxide reforming catalyst, method for preparing the same, and method for methane carbon dioxide reforming reaction

Abstract

The application relates to the technical field of catalysts, and discloses a methane-dioxide carbon reforming catalyst, a preparation method thereof and a methane-dioxide carbon reforming reaction method, the preparation method comprising the following steps: (1) mixing a soluble compound of Ce, a porous carbon material and a first complexing agent in the presence of a first solvent to obtain a first mixture; the specific surface area of the porous carbon material is 50-400 m 2 / g; (2) reacting the first mixture to form a gel, and then performing first calcination to obtain a CeO2 carrier; (3) contacting a La-Ni perovskite precursor with the CeO2 carrier, and then performing second calcination. The method adopts a template method to synthesize a porous CeO2 carrier, and then generates La-Ni perovskite oxide on the surface of the CeO2, so that the prepared catalyst can be used in methane-dioxide carbon reforming reaction, and the catalytic activity and the carbon deposition resistance of the catalyst can be remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a methane-carbon dioxide reforming catalyst and its preparation method, as well as a method for methane-carbon dioxide reforming reaction. Background Technology

[0002] In recent years, with the continuous development of industry, CO2 emissions in the atmosphere have been increasing, leading to global warming. Effectively utilizing CO2 as a resource can not only reduce CO2 emissions, but also provide a new resource for social development.

[0003] Methane reforming to syngas is an effective way to utilize CO2 while using relatively inexpensive natural gas to produce syngas (CO + H2), which can be further converted into other high-value-added downstream hydrocarbon products. However, the biggest problem with this reaction process is that the catalysts used in methane reforming to syngas are mainly nickel-based catalysts, which are prone to carbon deposition. If the carbon deposition problem cannot be effectively solved, it will severely limit the stability of the catalyst and the industrialization process.

[0004] Perovskites have become a focus of attention in many fields due to their excellent electrical conductivity, magnetism, thermoelectricity, piezoelectricity, and other properties, as well as their low preparation cost and thermodynamic and mechanical stability at high temperatures. Perovskite composite oxide materials are excellent conductors of oxygen ions and electrons under high-temperature conditions, and can release oxygen even under inert conditions, and can replenish oxygen through the Redox process. Therefore, using perovskite oxides as catalysts for methane-carbon dioxide reforming can effectively eliminate carbon deposits on the catalyst surface, thereby helping to improve the catalyst's resistance to carbon deposition. However, the catalyst activity and resistance to carbon deposition are still not entirely ideal. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of insufficient activity, poor stability, and poor anti-coking performance of existing methane-carbon dioxide reforming catalysts, and to provide a methane-carbon dioxide reforming catalyst and its preparation method, as well as a method for methane-carbon dioxide reforming reaction. The catalyst prepared by this method has good anti-coking ability and good catalytic activity.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a methane-carbon dioxide reforming catalyst, the method comprising:

[0007] (1) In the presence of a first solvent, a soluble compound of Ce, a porous carbon material, and a first complexing agent are mixed to obtain a first mixture; the porous carbon material has a specific surface area of ​​50-400 m². 2 / g;

[0008] (2) The first mixture is reacted to form a gel, and then subjected to a first calcination to obtain a CeO2 support;

[0009] (3) The La-Ni perovskite precursor is brought into contact with the CeO2 support and then subjected to a second calcination.

[0010] Preferably, based on the total amount of CeO2 support and La-Ni perovskite precursor calculated as LaNiO3, the content of CeO2 support is 20-60 wt%, preferably 30-50 wt%; and the content of La-Ni perovskite precursor calculated as LaNiO3 is 40-80 wt%, preferably 50-70 wt%.

[0011] Preferably, the method for preparing the La-Ni perovskite precursor includes: mixing a La source, a Ni source, and a solvent under stirring conditions in the presence of a second complexing agent, wherein the mixing temperature is 30-80°C and the mixing time is 6-13 h.

[0012] A second aspect of the present invention provides a methane-carbon dioxide reforming catalyst prepared by the above-described preparation method.

[0013] A third aspect of the present invention provides a method for a methane-carbon dioxide reforming reaction, comprising: contacting methane and carbon dioxide with a catalyst under reforming reaction conditions, wherein the catalyst is the aforementioned methane-carbon dioxide reforming catalyst.

[0014] The preparation method provided by this invention first synthesizes a porous CeO2 support using a template method, and then contacts the CeO2 support with a La-Ni perovskite precursor. The inventors discovered that by contacting the La-Ni perovskite precursor with porous CeO2, La-Ni perovskite oxide is generated on the CeO2 surface. The resulting catalyst, used in the methane-carbon dioxide reforming reaction, significantly enhances the catalyst's catalytic activity and resistance to carbon deposition. This is likely because CeO2 with a certain number and structure of pores can form a strong interaction with the particles in the La-Ni perovskite precursor. This interaction improves the dispersibility of the La-Ni perovskite oxide and effectively controls its crystal structure. Simultaneously, it fully utilizes the abundant oxygen vacancies within cerium dioxide and the specific semiconductor properties of perovskite oxides, achieving a synergistic effect between these two properties and significantly improving the electron transfer capability of the active centers in the perovskite oxide. Attached Figure Description

[0015] Figure 1 This is the XRD pattern of the catalyst prepared in Example 1;

[0016] Figure 2 These are stability evaluation curves for the catalysts prepared in Examples 1, 2 and Comparative Example 1. Detailed Implementation

[0017] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] The first aspect of this invention provides a method for preparing a methane-carbon dioxide reforming catalyst, the method comprising:

[0019] (1) In the presence of a first solvent, a soluble compound of Ce, a porous carbon material, and a first complexing agent are mixed to obtain a first mixture; the porous carbon material has a specific surface area of ​​50-400 m². 2 / g;

[0020] (2) The first mixture is reacted to form a gel, and then subjected to a first calcination to obtain a CeO2 support;

[0021] (3) The La-Ni perovskite precursor is brought into contact with the CeO2 support and then subjected to a second calcination.

[0022] According to this invention, a porous carbon material is first used as a CeO2 support, and the pore structure of the CeO2 support is adjusted by utilizing the porous carbon material with an appropriate number of pores. Then, a La-Ni perovskite precursor is contacted with the CeO2 support to generate La-Ni perovskite oxide on the CeO2 surface. This catalyst, used in the methane-carbon dioxide reforming reaction, can significantly improve the catalyst's catalytic activity and resistance to carbon deposition. The reason for this is likely that the CeO2 with a certain number and structure of pores can form a strong interaction with the particles in the La-Ni perovskite precursor, which can both improve the dispersibility of the La-Ni perovskite oxide and significantly enhance the electron transfer capability of the active centers of the perovskite oxide.

[0023] In this invention, a specific surface area of ​​50-400 m² is used. 2 Using porous carbon material with a certain number of pores as a template, CeO2 support is prepared. After the porous carbon material is removed by the first calcination, CeO2 support with an appropriate pore structure is formed. CeO2 with a certain number of pores and pore structure can form a strong interaction with the particles in the La-Ni perovskite precursor, which can not only improve the dispersibility of La-Ni perovskite oxide, but also significantly improve the electron transfer ability of the active center of perovskite oxide, thereby improving the catalytic activity and anti-carbon deposition performance of the catalyst.

[0024] In this invention, the specific surface area of ​​the porous carbon material can be 50-400 m². 2 Any value between / g, for example, 50m 2 / g、60m 2 / g, 70m 2 / g、80m 2 / g、90m 2 / g, 100m 2 / g、110m 2 / g、120m 2 / g、130m 2 / g, 140m 2 / g, 150m 2 / g、160m 2 / g、170m 2 / g、180m 2 / g、190m 2 / g、200m 2 / g、210m 2 / g、220m 2 / g、230m 2 / g、250m 2 / g、280m 2 / g、300m 2 / g, 350m 2 / g、400m 2 The specific surface area is typically defined as a value such as / g or a range between the two, preferably 100-250m². 2 / g. Using porous carbon materials with the above-mentioned preferred specific surface area, the prepared CeO2 has a suitable pore structure, thereby improving the dispersion ability of perovskite oxide on the CeO2 surface and the synergistic ability between the two, which is beneficial to further improve the catalytic activity and anti-carbon deposition performance of the catalyst.

[0025] In some preferred embodiments, the porous carbon material has a relatively regular pore structure. Preferably, the average pore size of the porous carbon material is 5-20 nm, and more preferably 8-15 nm. In the above preferred embodiments, it is beneficial to regulate the pore structure of CeO2, thereby regulating the crystal structure and grain size of perovskite oxide.

[0026] In this invention, the specific surface area and average pore size of the porous carbon material are measured by a nitrogen adsorption characterization method.

[0027] This invention allows for a wide range of specific types of porous carbon materials. Any porous carbon material possessing the aforementioned number and structure of pores, and capable of being removed by subsequent calcination, can be used in this invention. Furthermore, this invention does not impose any particular limitation on the source of the porous carbon material; it can be commercially available or prepared using any method known in the art. This invention also does not impose any special requirements on the shape or other characteristics of the porous carbon material, as long as it meets the aforementioned pore structure requirements. Preferably, the porous carbon material is selected from at least one of activated carbon, carbon nanotubes, and carbon fibers. The carbon nanotubes can be single-walled carbon nanotubes and / or multi-walled carbon nanotubes.

[0028] Preferably, the activated carbon has a particle diameter of 50-100 μm.

[0029] Preferably, the carbon nanotubes have a diameter of 5-20 nm and a length of 100-300 nm.

[0030] Preferably, the carbon fiber has a fiber diameter of 10-60 μm and a fiber length of 0.5-2 mm.

[0031] In this invention, by controlling the amount of porous carbon material and Ce soluble compounds, the pore structure of the CeO2 support can be further optimized, which is beneficial to further improve the interaction between CeO2 and La-Ni perovskite in the prepared catalyst and improve the anti-carbon deposition performance. Preferably, the mass ratio of the porous carbon material to the Ce-soluble compound calculated as CeO2 is (0.05-2):1, for example, it can be a typical but not limiting mass or a range between the two such as 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, etc. Preferably, the mass ratio of the porous carbon material to the Ce-soluble compound calculated as CeO2 is (0.2-1):1.

[0032] In this invention, the introduction of a first complexing agent facilitates the full fusion between the cerium precursor and the carbon material, and forms a good binding force during the reaction process, thereby giving full play to the role of the carbon material pore template agent.

[0033] According to the present invention, preferably, the molar ratio of the Ce-soluble compound to the first complexing agent, calculated as Ce element, is (0.5-3):1, more preferably (1-2):1.

[0034] Preferably, the first complexing agent is selected from citric acid and / or ethylenediaminetetraacetic acid.

[0035] In this invention, there are no particular limitations on the mixing conditions in step (1), as long as the components are thoroughly and evenly mixed. Preferably, the mixing temperature in step (1) is 30-80℃, more preferably 30-70℃, and the mixing time is 1-6h, more preferably 3-5h.

[0036] In this invention, there are no particular requirements for the mixing order in step (1). The Ce-soluble compound, porous carbon material, and first complexing agent can be added together to the first solvent for mixing. Alternatively, the first complexing agent and porous carbon material can be added to the first solvent for one-step mixing, and then the Ce-soluble compound can be added for two-step mixing. Preferably, the first complexing agent and porous carbon material are added to the first solvent for one-step mixing for 1-2 hours, and then the Ce-soluble compound is added for two-step mixing for 2-4 hours. The temperatures for the one-step mixing and the two-step mixing can be the same or different, both satisfying the above mixing conditions.

[0037] According to the present invention, the reaction conditions in step (2) are such that a gel can be formed. Preferably, the reaction conditions in step (2) include: a temperature of 60-90°C, more preferably 70-90°C; and a time of 8-20h, more preferably 8-12h.

[0038] Preferably, the method further includes drying the gel before performing the first calcination. The present invention does not particularly limit the drying conditions, as long as the gel can be dried. Preferably, the drying temperature is 100-120°C.

[0039] Preferably, the conditions for the first roasting in step (2) include: a temperature of 500-800℃, preferably 500-600℃, and a time of 6-20h, preferably 6-12h.

[0040] The present invention allows for a wide range of choices for the first solvent in step (1). Preferably, the first solvent is water. The present invention also does not impose any particular limitation on the amount of solvent used, as long as the components are sufficiently dispersed and mixed.

[0041] In this invention, the range of soluble compounds for Ce is relatively wide, as long as Ce element can be provided. They can be selected from soluble organic salts and / or inorganic salts of Ce. Preferably, the soluble compounds for Ce are selected from at least one of cerium nitrate, cerium acetate, and cerium oxalate.

[0042] The soluble compounds of Ce may also contain water of crystallization, as is well known to those skilled in the art.

[0043] In this invention, the La-Ni perovskite has a perovskite-type crystal structure, and its general molecular formula can be represented as LaNiO3. The La-Ni perovskite precursor refers to a mixture of La-Ni perovskite that can be obtained through gelation and calcination, and can be a solution or a sol. Preferably, the La-Ni perovskite precursor is in a sol state. Using the above-mentioned preferred embodiments is beneficial for further improving the dispersibility of La-Ni perovskite on the CeO2 support surface, and further improving the catalyst activity and anti-carbon deposition performance.

[0044] In a further preferred embodiment, the method for preparing the La-Ni perovskite precursor includes: mixing a La source, a Ni source, and a solvent under stirring conditions in the presence of a second complexing agent, wherein the mixing temperature is 30-80°C and the mixing time is 1-8 hours. The La-Ni perovskite precursor prepared by the above preferred method, when in contact with the CeO2 support, facilitates full fusion between the perovskite and CeO2, thereby enhancing the synergistic effect between the two.

[0045] Preferably, the mixing temperature is 30-50℃ and the mixing time is 3-6 hours.

[0046] In this invention, the mixing method may involve first dissolving the second complexing agent in a solvent, and then mixing it with the La source and Ni source. Preferably, the stirring rate is 100-200 rpm.

[0047] Preferably, the second complexing agent is selected from citric acid and / or ethylenediaminetetraacetic acid.

[0048] According to some preferred embodiments of the present invention, the molar ratio of the Ni source to the La source, based on metal elements, is (0.5-2):1, preferably (0.5-1.5):1.

[0049] Preferably, the total molar amount of the La source and Ni source, calculated as metal elements, is in a molar ratio of 0.5-3:1 to the second complexing agent, more preferably 0.6-2:1.

[0050] Preferably, the amount of solvent used is such that the total concentration of the La source and Ni source, calculated as metal elements, is 0.3-2 mol / L, more preferably 1-2 mol / L.

[0051] In this invention, the selection range for the specific types of La and Ni sources is relatively wide. Soluble organic or inorganic salts of metals can be used in this invention, for example, at least one selected from metal nitrates, acetates, and oxalates. The La and Ni sources may also contain water of crystallization, as is well known to those skilled in the art.

[0052] Preferably, the contact temperature in step (3) is 60-90℃, and more preferably 60-80℃.

[0053] According to the present invention, in step (3), the method of contacting the La-Ni perovskite precursor with the CeO2 support includes: mixing the La-Ni perovskite precursor with the CeO2 support under stirring conditions. The present invention does not have special requirements for the mixing conditions, as long as the La-Ni perovskite precursor and the CeO2 support are mixed evenly.

[0054] The present invention has a wide range of solvents that can be selected, and can be the same as the range of solvents selected for the first solvent.

[0055] According to the present invention, preferably, the catalyst prepared comprises a CeO2 support and a La-Ni perovskite, wherein the general molecular formula of the La-Ni perovskite can be represented as LaNiO3.

[0056] According to some preferred embodiments of the present invention, the CeO2 support content is 20-60 wt%, preferably 30-50 wt%, based on the total amount of the CeO2 support and the La-Ni perovskite precursor calculated as LaNiO3; for example, it can be a typical but not limiting content value such as 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, or a range between the two; the La-Ni perovskite precursor content is 40-80 wt%, preferably 50-70 wt%, for example, it can be a typical but not limiting content value such as 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, or a range between the two.

[0057] Preferably, the second calcination temperature is 500-800℃, more preferably 500-600℃, and the time is 6-20h, more preferably 8-12h.

[0058] According to a preferred embodiment of the present invention, the preparation method includes:

[0059] S1. In the presence of a first solvent, a soluble compound of Ce, a porous carbon material, and a first complexing agent are mixed to obtain a first mixture; the porous carbon material has a specific surface area of ​​100-250 m². 2 / g;

[0060] S2. React the first mixture to form a gel, and then perform a first calcination to obtain a CeO2 support;

[0061] S3. Under stirring conditions and in the presence of a second complexing agent, La source, Ni source and solvent are mixed to obtain La-Ni perovskite precursor; the mixing temperature is 30-50℃ and the time is 3-6h.

[0062] S4. The La-Ni perovskite precursor is brought into contact with the CeO2 support, and then a second calcination is performed.

[0063] The preferred embodiment described above is beneficial for further enhancing the interaction between the La-Ni perovskite and the support in the catalyst, thereby improving its resistance to carbon deposition. The reason for this is likely that CeO2 with a certain number and structure of pores can form a strong interaction with the particles in the La-Ni perovskite precursor. This interaction improves the dispersibility of the La-Ni perovskite oxide and effectively controls its crystal structure. Simultaneously, it fully utilizes the abundant oxygen vacancies within cerium dioxide and the specific semiconductor properties of perovskite oxides, achieving a synergistic effect between these two characteristics. This significantly improves the electron transfer capability of the active centers of the perovskite oxide. This effectively prevents methane cracking and carbon deposition during the reaction. Furthermore, even if a small amount of carbon deposits form on the catalyst surface, the catalyst's unique electronic properties allow the carbon deposits to react rapidly with the carbon generated during the reaction, thus eliminating the carbon deposits.

[0064] A second aspect of the present invention provides a methane-carbon dioxide reforming catalyst prepared by the above-described preparation method.

[0065] According to the present invention, the catalyst comprises a CeO2 support and La-Ni perovskite supported on the CeO2 support. Preferably, based on the total amount of the catalyst, the content of the CeO2 support is 20-60 wt%, preferably 30-50 wt%, for example, typical and non-limiting content values ​​such as 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, or a range between the two; the content of the La-Ni perovskite is 40-80 wt%, preferably 50-70 wt%, for example, typical and non-limiting content values ​​such as 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, or a range between the two. It is understood that when the catalyst consists only of the CeO2 support and the La-Ni perovskite supported on the CeO2 support, the sum of their contents satisfies the 100% principle.

[0066] The catalyst may also contain a very small amount of NiO, but the content of NiO is negligible in this invention.

[0067] In this invention, the content of each component in the catalyst is obtained by X-ray fluorescence spectroscopy (XRF) characterization method.

[0068] The presence of a La-Ni perovskite structure in the catalyst was confirmed by X-ray diffraction (XRD).

[0069] Preferably, the catalyst has a specific surface area of ​​50-250 m². 2 / g, preferably 100-180m 2 / g.

[0070] A third aspect of the present invention provides a method for a methane-carbon dioxide reforming reaction, comprising: contacting methane and carbon dioxide with a catalyst under reforming reaction conditions, wherein the catalyst is the methane-carbon dioxide reforming catalyst provided in the second aspect.

[0071] Preferably, the reforming reaction conditions include: a molar ratio of methane to carbon dioxide of 1:1-1.5, preferably 1:1.2-1.5; a reaction temperature of 700-950℃, preferably 750-900℃; a pressure of 0.1-0.5 MPa, preferably 0.1-0.3 MPa; and a carbon hourly space velocity (CHSV) of 1000-6000 h⁻¹ for the feed gas. -1 Preferably 2000-5000h -1 .

[0072] According to some preferred embodiments of the present invention, the method further includes: reducing the catalyst in a hydrogen atmosphere prior to the contact.

[0073] Preferably, the reduction conditions include: a temperature of 400-600℃, more preferably 450-550℃; a time of 2-20h, more preferably 5-12h; and a pressure of 0.1-0.5MPa, more preferably 0.1-0.3MPa.

[0074] Preferably, the hydrogen atmosphere can be provided by hydrogen or a mixture of hydrogen and an inert gas, wherein the inert gas can be selected from nitrogen and / or argon. Preferably, the volume content of hydrogen in the mixture of hydrogen and inert gas is 5-20%.

[0075] The present invention will be described in detail below through embodiments.

[0076] Unless otherwise specified, all raw materials used are commercially sourced.

[0077] Example 1

[0078] (1) Dissolve 50g of citric acid in water to form a solution, and then add 50g of multi-walled carbon nanotubes (purchased from Aladdin Company, with a diameter of 10-15nm, a length of 100-150nm, and a specific surface area of ​​200m²). 2A solution containing 126 g of cerium nitrate hexahydrate (with an average pore size of 10 nm) was poured into citric acid solution and stirred at 30 °C for 1 h. 126 g of cerium nitrate hexahydrate was dissolved in distilled water and added dropwise to the above solution, and stirred thoroughly at 30 °C for 3 h. The temperature was then raised to 80 °C and stirred for 10 h to evaporate the water, yielding a gel. The resulting gel was dried at 100 °C. The dried product was placed in a muffle furnace and calcined at 600 °C for 6 h in air to obtain porous CeO2.

[0079] (2) Dissolve 100g of citric acid in water to obtain a complexing agent solution. Dissolve 88g of lanthanum nitrate hexahydrate and 59g of nickel nitrate hexahydrate in water to obtain lanthanum nitrate solution and nickel nitrate solution, respectively. Then, add the above aqueous solutions dropwise to the complexing agent solution, with the amount of water used such that the total concentration of the La source and Ni source in the resulting mixed solution, calculated as metal elements, is 1mol / L. Stir at 40℃ for 6h to form a sol.

[0080] (3) Under stirring conditions, 40g of porous CeO2 was mixed with the above sol at a contact temperature of 80℃ to evaporate the water and obtain a gel. The obtained gel was dried at 120℃. The dried product was placed in a muffle furnace and calcined at 600℃ for 8h to obtain the catalyst, named CAT-1. The composition and structural parameters of the catalyst are shown in Table 1.

[0081] The obtained catalyst was characterized by XRD, such as Figure 1 As shown, the catalyst includes CeO2 and LaNiO3 with a perovskite structure. Furthermore, characteristic peaks of NiO are present in the 2θ range of 35-45°; these peaks are relatively sharp and narrow, indicating that the NiO content is low and negligible.

[0082] Example 2

[0083] (1) Dissolve 50g of citric acid in water to form a solution, and add 20g of activated carbon (purchased from Aladdin Company, with a particle diameter of 50-100μm and a specific surface area of ​​200m²). 2 The solution (containing 126 g of cerium nitrate hexahydrate with an average pore size of 8 nm) was poured into a citric acid solution and stirred at 30 °C for 1 h. 126 g of cerium nitrate hexahydrate was dissolved in distilled water and added dropwise to the above solution, and stirred thoroughly at 30 °C for 3 h. The temperature was then raised to 90 °C and stirred for 8 h to evaporate the water, yielding a gel. The resulting gel was dried at 110 °C. The dried product was placed in a muffle furnace and calcined at 600 °C for 6 h in air to obtain porous CeO2.

[0084] (2) Dissolve 100g of citric acid in water to obtain a complexing agent solution. Dissolve 60g of lanthanum nitrate hexahydrate and 40g of nickel nitrate hexahydrate in water to obtain lanthanum nitrate solution and nickel nitrate solution, respectively. Then, add the above solutions dropwise to the complexing agent solution, with the amount of water used such that the total concentration of the La source and Ni source in the resulting mixed solution, calculated as metal elements, is 1mol / L. Stir at 50℃ for 3h to obtain a sol.

[0085] (3) Under stirring conditions, 40g of porous CeO2 was contacted with the above La-Ni perovskite precursor at a contact temperature of 80℃ to evaporate moisture and obtain a gel. The obtained gel was dried at 120℃. The dried product was placed in a muffle furnace and calcined at 600℃ for 8h to obtain the catalyst, named CAT-2. Its XRD pattern is similar to... Figure 1 Similarly, the composition and structural parameters of the catalyst are shown in Table 1.

[0086] Example 3

[0087] (1) Dissolve 80g of citric acid in water to form a solution. Add 20g of carbon fiber (purchased from Aladdin Company, fiber diameter 10-60μm, fiber length 0.5-2mm, specific surface area 120m²). 2 A solution containing 200g of cerium nitrate hexahydrate (with an average pore size of 10nm) was poured into a citric acid solution and stirred at 30°C for 1 hour. 200g of cerium nitrate hexahydrate was dissolved in distilled water and added dropwise to the solution, and stirred thoroughly at 30°C for 3 hours. The temperature was then raised to 90°C and stirred for 8 hours to evaporate the water, yielding a gel. The resulting gel was dried at 120°C. The dried product was placed in a muffle furnace and calcined at 600°C for 12 hours in air to obtain porous CeO2.

[0088] (2) Dissolve 100g of citric acid in water to obtain a complexing agent solution. Dissolve 80g of lanthanum nitrate hexahydrate and 40g of nickel nitrate hexahydrate in 200mL of water to obtain lanthanum nitrate solution and nickel nitrate solution, respectively. Then, add the above solutions dropwise to the complexing agent solution, using water in such a way that the total concentration of the La source and Ni source in the resulting mixed solution, calculated as metal elements, is 1mol / L. Stir at 30℃ for 6h to form a sol.

[0089] (3) Under stirring conditions, 40g of porous CeO2 was poured into the above sol at 80℃ to evaporate the water and obtain a gel. The obtained gel was dried at 120℃. The dried product was placed in a muffle furnace and calcined at 600℃ for 8h to obtain a catalyst, named CAT-3, whose XRD pattern is similar to... Figure 1 Similarly, the composition and structural parameters of the catalyst are shown in Table 1.

[0090] Example 4

[0091] The method is the same as in Example 1, except that the mass of the multi-walled carbon nanotubes used is 5g.

[0092] The obtained catalyst is designated CAT-4. The composition and structural parameters of the catalyst are shown in Table 1.

[0093] Example 5

[0094] The method is the same as in Example 1, except that the specific surface area of ​​the multi-walled carbon nanotubes used is 60 m². 2 / g, with an average pore size of 30nm (tube diameter of 20-35nm, length of 100-300nm, purchased from Aladdin).

[0095] The obtained catalyst is designated CAT-5. The composition and structural parameters of the catalyst are shown in Table 1.

[0096] Example 6

[0097] Following the method of Example 1, except that steps (2) and (3) are omitted, 100g of citric acid is dissolved in water to obtain a complexing agent solution. 88g of lanthanum nitrate hexahydrate, 59g of nickel nitrate hexahydrate, and 40g of porous CeO2 obtained in step (1) are added to the above solution, stirred at 40°C for 6h, then heated to 80°C and stirred for 8h to evaporate the water, obtaining a gel. The obtained gel is dried at 120°C. The dried product is placed in a muffle furnace and calcined at 600°C for 8h to obtain a catalyst, named CAT-6. The composition and structural parameters of the catalyst are shown in Table 1.

[0098] Comparative Example 1

[0099] 100g of citric acid was dissolved in water to obtain a complexing agent solution. 88g of lanthanum nitrate hexahydrate and 59g of nickel nitrate hexahydrate were dissolved in water to obtain lanthanum nitrate solution and nickel nitrate solution, respectively. These aqueous solutions were then added dropwise to the complexing agent solution, with the amount of water used ensuring that the total concentration of the La and Ni sources (based on metal elements) in the resulting mixed solution was 1 mol / L. The mixture was stirred at 40℃ for 6 h to form a sol. The temperature was then raised to 80℃ and stirred for 9 h to evaporate the water, yielding a gel. The resulting gel was dried at 120℃. The dried product was placed in a muffle furnace and calcined at 600℃ for 8 h to obtain the LaNiO3 catalyst, named DCAT-1. The composition and structural parameters of the catalyst are shown in Table 1.

[0100] Comparative Example 2

[0101] (1) Dissolve 100g of citric acid in water to form a solution, add 20g of multi-walled carbon nanotubes to the solution, and stir at 30℃ for 1h. Dissolve 126g of cerium nitrate hexahydrate in distilled water and add it dropwise to the above solution, and stir thoroughly at 30℃ for 3h. Then raise the temperature to 80℃ and stir for 9h to evaporate the water, obtaining a gel. Dry the obtained gel at 100℃. Place the dried product in a muffle furnace and calcine at 600℃ for 6h in air atmosphere to obtain porous CeO2.

[0102] (2) Dissolve 100g of citric acid in a certain amount of water to obtain a complexing agent solution. Dissolve 59g of nickel nitrate hexahydrate in water and add it to the complexing agent solution. The amount of water used is such that the concentration of Ni element in the resulting mixed solution is 1mol / L. Stir at 40℃ for 6h. Add 40g of porous CeO2 obtained in step (1) to the above solution. Then raise the temperature to 80℃ and evaporate the water under stirring to obtain a gel. Dry the obtained gel at 120℃. Place the dried product in a muffle furnace and calcine at 600℃ for 8h to obtain a NiO catalyst supported on porous CeO2. Named DCAT-2. The composition and structural parameters of the catalyst are shown in Table 1.

[0103] Comparative Example 3

[0104] (1) Dissolve 50g of citric acid in water to form a solution. Dissolve 126g of cerium nitrate hexahydrate in distilled water and add it dropwise to the above solution. Stir thoroughly at 30℃ for 3h. Then raise the temperature to 80℃ and stir for 10h to evaporate the water, obtaining a gel. Dry the obtained gel at 100℃. Place the dried product in a muffle furnace and calcine at 600℃ for 6h in air atmosphere to obtain CeO2.

[0105] (2) Dissolve 100g of citric acid in water to obtain a complexing agent solution. Dissolve 88g of lanthanum nitrate hexahydrate and 59g of nickel nitrate hexahydrate in water to obtain lanthanum nitrate solution and nickel nitrate solution, respectively. Then, add the above aqueous solutions dropwise to the complexing agent solution, with the amount of water used such that the total concentration of the La source and Ni source in the resulting mixed solution, calculated as metal elements, is 1mol / L. Stir at 40℃ for 6h to form a sol.

[0106] (3) Under stirring conditions, 40g of CeO2 was mixed with the above sol at 80℃ to evaporate the water and obtain a gel. The obtained gel was dried at 120℃. The dried product was placed in a muffle furnace and calcined at 600℃ for 8h to obtain the catalyst, named DCAT-3. The composition and structural parameters of the catalyst are shown in Table 1.

[0107] Table 1

[0108] serial number <![CDATA[Content of CeO2 carrier, wt%]]> La-Ni perovskite content (wt%) <![CDATA[Specific surface area m 2 / g]]> CAT-1 34 66 150.1 CAT-2 43 57 169.3 CAT-3 36 64 160.2 CAT-4 34 66 80.6 CAT-5 34 66 50.3 CAT-6 34 66 45.6 DCAT-1 0 100 10.5 DCAT-2 73 0 (the rest is NiO) 169.1 DCAT-3 34 66 40.2

[0109] Catalyst evaluation:

[0110] Catalyst performance was evaluated in an atmospheric pressure fixed-bed reactor.

[0111] 300 mg of the catalyst (40-60 mesh) prepared above was mixed evenly with 1.5 g of quartz sand (40-60 mesh) and placed into a steel tube. The steel tube reactor was then fixed in a heating furnace and reduced by programmed temperature rise for 10 h in a mixed atmosphere of N2 (20 mL / min) and H2 (20 mL / min). The reduction temperature was 450 °C and the pressure was 0.1 MPa.

[0112] After reduction, the feed gas was switched to a methane to carbon dioxide molar ratio of 1:1.2, the reaction temperature was 750℃, and the carbon hourly space velocity was 20000 h⁻¹. -1 The pressure is normal.

[0113] After 20 hours of reaction, the product was collected, and its composition was analyzed by gas chromatography. The CO2 and CH4 conversion rates were calculated, and the amount of carbon deposited in the catalyst was tested using thermogravimetric analysis in air. The results are shown in Table 2. The stability evaluation curves of the catalysts prepared in Examples 1, 2, and Comparative Example 1 are shown below. Figure 2 As shown.

[0114]

[0115]

[0116] Table 2

[0117] serial number <![CDATA[CH4 conversion rate (%)]]> <![CDATA[CO2 conversion rate (%)]]> Carbon deposits (mg / gcat) CAT-1 89.3 83.6 0.21 CAT-2 85.1 81.2 0.43 CAT-3 86.3 80.5 0.54 CAT-4 84.2 81.2 0.36 CAT-5 83.5 82.1 0.65 CAT-6 82.1 79.6 0.96 CAT-7 79.6 78.6 1.02 DCAT-1 61.2 30.5 8.03 DCAT-2 40.2 10.5 15.96 DCAT-3 45.2 23.8 10.36

[0118] As can be seen from the results in Table 2, the present invention uses La-Ni perovskite precursor to contact porous CeO2 to generate La-Ni perovskite oxide on the CeO2 surface. The resulting catalyst can be used in the methane-carbon dioxide reforming reaction, which can significantly improve the catalyst's catalytic activity and anti-carbon deposition ability, resulting in high conversion rates of methane and carbon dioxide and low carbon deposition.

[0119] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a methane-carbon dioxide reforming catalyst, characterized in that, The preparation method includes: (1) In the presence of a first solvent, a soluble compound of Ce, a porous carbon material and a first complexing agent are mixed to obtain a first mixture; The porous carbon material has a specific surface area of ​​100-250 m². 2 / g; The average pore size of the porous carbon material is 8-15 nm. (2) The first mixture is reacted to form a gel, and then subjected to a first calcination to obtain a CeO2 support; (3) The La-Ni perovskite precursor is brought into contact with the CeO2 support, and then a second calcination is performed; The La-Ni perovskite precursor is in a sol state; The method for preparing the La-Ni perovskite precursor includes: mixing a La source, a Ni source, and a solvent under stirring conditions in the presence of a second complexing agent, wherein the mixing temperature is 30-80℃ and the mixing time is 1-8h; The molar ratio of the Ni source to the La source, calculated by metallic elements, is (0.5-2):1; Based on the total amount of CeO2 support and La-Ni perovskite precursor (calculated as LaNiO3), the content of CeO2 support is 30-50 wt%; the content of La-Ni perovskite precursor (calculated as LaNiO3) is 50-70 wt%.

2. The preparation method according to claim 1, wherein, The porous carbon material is selected from at least one of activated carbon, carbon nanotubes, and carbon fibers.

3. The preparation method according to claim 1, wherein, The mass ratio of the porous carbon material to the soluble compound of Ce (calculated as CeO2) is (0.05-2):

1.

4. The preparation method according to claim 3, wherein, The mass ratio of the porous carbon material to the soluble compound of Ce, calculated as CeO2, is (0.2-1):

1.

5. The preparation method according to claim 1, wherein, The molar ratio of the soluble Ce compound to the first complexing agent, calculated as Ce element, is (0.5-3):

1.

6. The preparation method according to claim 5, wherein, The molar ratio of the soluble compound of Ce, calculated as elemental Ce, to the first complexing agent is (1-2):

1.

7. The preparation method according to claim 1, wherein, The first complexing agent is selected from citric acid and / or ethylenediaminetetraacetic acid.

8. The preparation method according to claim 1, wherein, The mixing temperature in step (1) is 30-80℃, and the time is 1-6h.

9. The preparation method according to claim 1, wherein, The reaction conditions described in step (2) include: a temperature of 60-90℃ and a time of 8-20h.

10. The preparation method according to claim 1, wherein, The conditions for the first roasting in step (2) include: a temperature of 500-800℃ and a time of 6-20h.

11. The preparation method according to claim 10, wherein, The conditions for the first roasting in step (2) include: a temperature of 500-600℃ and a time of 6-12h.

12. The preparation method according to claim 1, wherein, The second complexing agent is selected from citric acid and / or ethylenediaminetetraacetic acid.

13. The preparation method according to claim 1, wherein, The molar ratio of the Ni source to the La source, calculated by metallic elements, is (0.5-1.5):

1.

14. The preparation method according to claim 1, wherein, The total molar amount of the La source and Ni source, calculated as metal elements, is in a molar ratio of 0.5-3:1 to the second complexing agent.

15. The preparation method according to claim 1, wherein, The amount of solvent used is such that the total concentration of the La source and Ni source, calculated as metal elements, is 0.3-2 mol / L.

16. The preparation method according to claim 10, wherein, The contact temperature in step (3) is 60-90℃.

17. The preparation method according to any one of claims 1-15, wherein, The second roasting temperature is 500-800℃, and the time is 6-20h.

18. The preparation method according to claim 17, wherein, The second roasting temperature is 500-600℃, and the time is 8-12h.

19. A methane-carbon dioxide reforming catalyst prepared by any one of claims 1-18.

20. A method for a methane-carbon dioxide reforming reaction, characterized in that, include: Under reforming reaction conditions, methane and carbon dioxide are contacted with a catalyst, wherein the catalyst is the methane-carbon dioxide reforming catalyst as described in claim 19.

21. The method according to claim 20, wherein, The reforming reaction conditions include: a molar ratio of methane to carbon dioxide of 1:(1-1.5), a reaction temperature of 750-950℃, a pressure of 0.1-0.5 MPa, and a carbon hourly space velocity (CHSV) of 1000-6000 h⁻¹ for the feed gas. -1 .

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