Multi-component composite metal oxide catalyst, preparation method and application
By preparing a multi-component composite metal oxide catalyst, the problem of deactivation of nickel-based catalysts at high temperatures was solved, achieving efficient conversion of CO2 and CH4 and long-term stable operation, which is suitable for the field of energy and environmental catalysis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TAIYUAN UNIVERSITY OF SCIENCE AND TECHNOLOGY
- Filing Date
- 2026-03-27
- Publication Date
- 2026-05-19
AI Technical Summary
Traditional nickel-based catalysts are prone to rapid deactivation in high-temperature dry reforming reactions due to surface carbonization and sintering, resulting in insufficient catalyst activity and stability.
The catalyst is a multi-component composite metal oxide catalyst, prepared from nickel-magnesium-aluminum hydrotalcite doped with active metals. Through in-situ doping, a solid solution is formed, which enhances the basic sites and oxygen vacancies, regulates the dynamic balance of carbon deposition and carbon elimination, and promotes the efficient conversion of CO2 and CH4.
At 700-800 ℃, the conversion rates of CO2 and CH4 both reached over 80%, and the catalyst operated stably for over 200 h, significantly improving the activity and stability of the catalyst and demonstrating its potential for industrial application.
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Figure CN122057516A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of energy and environmental catalysis, specifically relating to a multi-component composite metal oxide catalyst, its preparation method, and its application. Background Technology
[0002] Carbon dioxide (CO2) and methane (CH4), as major greenhouse gases, cause global climate change due to their large-scale emissions, posing a serious challenge to the world today. The CO2-CH4 dry reforming reaction (DRM: CO2 + CH4 → 2CO + 2H2) can simultaneously convert both greenhouse gases into syngas (CO and H2), which can then be used to produce high-value-added chemicals. This process can mitigate the greenhouse effect caused by CO2 and CH4 emissions and also realize the resource utilization of CO2 and CH4, which is of great significance to achieving my country's "dual carbon" goals.
[0003] CO2 and CH4 molecules have stable structures, with C=O bond energies of 750 kJ / mol and CH bond energies of 439 kJ / mol. Therefore, highly active catalysts are needed to achieve efficient conversion and utilization of CO2 and CH4. Recent studies have shown that nickel-based catalysts exhibit high activity for the DRM reaction and are inexpensive and abundant compared to precious metals, making them considered the most promising catalysts for industrial applications. However, maintaining the high temperatures (typically >700 °C) required for the DRM reaction can lead to rapid deactivation due to surface carbon accumulation and sintering, which damages active sites and the catalyst structure. Therefore, improving the activity and stability of nickel-based catalysts is a key technology for achieving high-value utilization of CO2 and CH4, and is of great significance for green chemical engineering and sustainable energy development.
[0004] In view of this, the present invention is hereby proposed. Summary of the Invention
[0005] The purpose of this invention is to provide a multi-component composite metal oxide catalyst that solves the technical defect of traditional nickel-based catalysts being prone to rapid deactivation due to surface carbonization and sintering in high-temperature dry reforming reactions.
[0006] The technical solution adopted by this invention to solve its technical problem is:
[0007] A multi-component composite metal oxide catalyst is disclosed, wherein the catalyst is prepared by calcining a precursor having a hydrotalcite structure, the precursor being a nickel-magnesium-aluminum hydrotalcite doped with an active metal; wherein, based on the total mass of the multi-component composite metal oxide catalyst, the mass fraction of nickel is 6%-12%; and the active metal is two selected from cobalt, copper, zinc, iron, gallium, and cerium, with the total mass fraction of the active metal being 2%-10% based on the total mass of the multi-component composite metal oxide catalyst.
[0008] The active metal is in situ doped into the nickel-magnesium-aluminum hydrotalcite and uniformly dispersed in the multi-component composite metal oxide catalyst in the form of a solid solution.
[0009] After the formation of the multi-component composite metal oxide catalyst, the enhanced basicity sites and abundant oxygen vacancies significantly improve the adsorption and activation of CO2 molecules on its surface, promoting the CH4 adsorption on the catalyst surface. x The consumption of species (carbon depletion process) effectively avoids the dynamic balance of carbon deposition and carbon depletion processes by regulating the interactions between multiple complex metals. x The accumulation of species on the catalyst surface enables the catalyst to maintain high activity and stability in the dry reforming reaction of methane.
[0010] Preferably, the active metal is a combination of two metals, selected from a combination of cobalt and iron, a combination of copper and cerium, a combination of cobalt and gallium, or a combination of cobalt and zinc.
[0011] More preferably, the combination of active metals and their corresponding total mass fraction are selected from any one of the following: a combination of cobalt and iron with a mass fraction of 6%; a combination of copper and cerium with a mass fraction of 8%; a combination of cobalt and gallium with a mass fraction of 8%; or a combination of cobalt and zinc with a mass fraction of 6%.
[0012] A method for preparing a multi-component composite metal oxide catalyst according to the present invention includes the following steps: S1, dissolving a nickel source, a magnesium source, an aluminum source, and the metal salt corresponding to the active metal in water and mixing them evenly to obtain a metal salt mixed solution; S2, adding the metal salt mixed solution dropwise to a 0.3-0.8 mol / L sodium carbonate solution while simultaneously adding an alkaline solution to maintain the pH value of the reaction system at a constant 9-10, and stirring the reaction at a temperature of 60-75°C to obtain a coprecipitated product; S3, collecting the coprecipitated product after the reaction by filtration, washing it with deionized water until neutral, and then drying it to obtain the precursor with a hydrotalcite structure; S4, calcining the precursor in an air atmosphere to obtain the multi-component composite metal oxide catalyst.
[0013] Preferably, in step S1, the molar ratio of divalent metal to trivalent metal in the metal salt mixed solution is 2-3.5:1; more preferably, the molar ratio of divalent metal to trivalent metal is 3:1. In this invention, divalent metals include cobalt, copper, and zinc, and trivalent metals include iron, gallium, and cerium.
[0014] Preferably, the metal salt solution includes nickel nitrate, magnesium nitrate, aluminum nitrate, and two of cobalt nitrate, copper nitrate, zinc nitrate, iron nitrate, gallium nitrate, and cerium nitrate.
[0015] Preferably, in step S1, the nickel source, magnesium source, aluminum source, and the metal salt corresponding to the active metal are all nitrates; in step S2, the alkaline solution is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 0.5-2 mol / L. Preferably, the pH value of the reaction system is constantly controlled at 10, and the stirring reaction time is 24 hours.
[0016] Preferably, in step S2, the concentration of the sodium carbonate solution is 0.3-0.8 mol / L.
[0017] Preferably, in step S3, the drying temperature is 80℃ and the drying time is 12h; in step S4, the calcination temperature is 750-900℃ and the calcination time is 3-6h, with a heating rate of 2℃ / min. Preferably, the calcination temperature is 800℃ and the calcination time is 5h.
[0018] In this invention, a metal solution, a sodium carbonate solution, and an alkaline solution are used to form a precursor for a hydrotalcite structure at an appropriate temperature. This method allows active metals to be in situ doped into nickel-magnesium-aluminum hydrotalcite, which is then uniformly dispersed in the form of a solid solution and subsequently calcined to form a multi-component composite metal oxide.
[0019] The precursor of the multi-component composite metal oxide catalyst is a hydrotalcite structure. The active metal is incorporated during the formation of the hydrotalcite precursor, and then the multi-component composite metal oxide is obtained by calcination. During this process, the active metal does not agglomerate. Therefore, this method can make the active metal uniformly dispersed and realize the in-situ doping of the active metal.
[0020] Application of the multi-component composite metal oxide catalyst described in this invention in the dry reforming reaction of carbon dioxide and methane.
[0021] Preferably, the application specifically includes the following steps: The multi-component composite metal oxide catalyst is loaded into a fixed-bed reactor and reduced under a hydrogen atmosphere (balanced by an inert gas, such as nitrogen) with a volume fraction of 5%-30%, and the reduction temperature is controlled at 650-750℃; after the reduction is completed, carbon dioxide and methane gases are introduced at a reaction temperature of 600-800℃ to carry out a dry reforming reaction, and the reaction space velocity is controlled at 5000 h⁻¹. -1 Up to 100,000 h -1 .
[0022] Preferably, the volume ratio of carbon dioxide gas to methane gas is 1:1; and the reduction treatment time is 1 hour.
[0023] The multi-component composite metal oxide catalyst provided by this invention uses nickel-magnesium-aluminum layered double hydroxide (TLD) as a precursor. The active metal is in-situ doped into the precursor during preparation, ultimately existing as a solid solution and well dispersed on the catalyst. By constructing this multi-component composite metal oxide catalyst, the dynamic balance between carbon deposition and carbon removal is effectively controlled. At 700-800 °C, both CO2 and CH4 conversion rates exceed 80%, while maintaining stable operation for over 200 h. This invention is the first to prepare a multi-component composite metal oxide catalyst and apply it to the field of methane dry reforming, achieving improved carbon dioxide and methane conversion rates while maintaining high stability, demonstrating potential for industrial application. Attached Figure Description
[0024] Figure 1 The graph shows the long-term stability test curve of the multi-component composite metal oxide catalyst prepared in Example 3 of the present invention in the dry reforming reaction of methane; wherein, the left vertical axis represents the conversion rate of carbon dioxide and methane (%), the right vertical axis represents the molar ratio of hydrogen to carbon monoxide in the product (H2 / CO), and the horizontal axis represents the reaction time (h). Figure 2 The image shows a transmission electron microscope (TEM) image of the multi-component composite metal oxide catalyst prepared in Example 3 of this invention at 100 nm. Figure 3 This is a locally magnified transmission electron microscope (TEM) image of the multi-component composite metal oxide catalyst prepared in Example 3 of the present invention at 50 nm. Detailed Implementation
[0025] The technical solution of the present invention will be further described in detail below through specific embodiments. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.
[0026] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.
[0027] Unless otherwise specified, the reagents used in the following examples can be purchased from a regular biochemical reagent store.
[0028] Example 1
[0029] A multi-component composite metal oxide catalyst is prepared by the following method:
[0030] 0.933 g of nickel nitrate hexahydrate, 6.470 g of magnesium nitrate hexahydrate, 3.520 g of aluminum nitrate nonahydrate, 0.404 g of cobalt nitrate hexahydrate, and 0.226 g of ferric nitrate nonahydrate were added to an aqueous solution and stirred until homogeneous. The molar ratio of divalent metals (nickel, magnesium, cobalt) to trivalent metals (iron, aluminum) was 3:1. Subsequently, the solution was added dropwise to a 0.5 mol / L sodium carbonate solution, while simultaneously adding sodium hydroxide solution at a concentration of 1 mol / L to maintain the pH at 10. After stirring for 24 h, the sample was collected by filtration, washed with deionized water until neutral, and then dried in a forced-air drying oven at 80 ℃ for 12 h. Finally, it was calcined at 800 ℃ for 5 h in air at a heating rate of 2 ℃ / min to obtain a multi-element composite metal oxide catalyst, wherein the mass fraction of nickel was 10% and the mass fraction of the doped active metals (cobalt, iron) was 6%.
[0031] The catalyst was loaded into a fixed-bed reactor and reduced for 1 h under a 20% hydrogen atmosphere at a reduction temperature of 750 °C. The reaction temperature was controlled at 700 °C. CO2 and CH4 gases were introduced at chamber pressure with a gas volume ratio of 1:1, and the reaction space velocity was controlled at 35,000 h⁻¹. -1 The steady-state CO2 conversion rate is 83%, the CH4 conversion rate is 80%, and it operates stably for over 200 hours.
[0032] Example 2
[0033] A multi-component composite metal oxide catalyst is prepared by the following method:
[0034] 0.958 g of nickel nitrate hexahydrate, 6.470 g of magnesium nitrate hexahydrate, 3.520 g of aluminum nitrate nonahydrate, 0.300 g of copper nitrate trihydrate, and 0.235 g of cerium nitrate hexahydrate were added to an aqueous solution and stirred until homogeneous. The molar ratio of divalent metals (nickel, magnesium, and copper) to trivalent metals (cerium and aluminum) was 3:1. Subsequently, the solution was added dropwise to a 0.5 mol / L sodium carbonate solution, while simultaneously adding sodium hydroxide solution at a concentration of 1 mol / L to maintain the pH at 10. After stirring for 24 h, the sample was collected by filtration, washed with deionized water until neutral, and then dried in a forced-air drying oven at 80 ℃ for 12 h. Finally, it was calcined at 800 ℃ for 5 h in air at a heating rate of 2 ℃ / min to obtain a multi-element composite metal oxide catalyst, wherein the mass fraction of nickel was 10% and the mass fraction of the doped active metals (copper and cerium) was 8%.
[0035] The catalyst was loaded into a fixed-bed reactor and reduced for 1 h under a 20% hydrogen atmosphere at a reduction temperature of 750 °C. The reaction temperature was controlled at 700 °C. CO2 and CH4 gases were introduced at chamber pressure with a gas volume ratio of 1:1, and the reaction space velocity was controlled at 35,000 h⁻¹. -1 The steady-state CO2 conversion rate is 83%, the CH4 conversion rate is 80%, and it operates stably for over 200 hours.
[0036] Example 3
[0037] A multi-component composite metal oxide catalyst is prepared by the following method:
[0038] 0.963 g of nickel nitrate hexahydrate, 6.470 g of magnesium nitrate hexahydrate, 3.520 g of aluminum nitrate nonahydrate, 0.518 g of cobalt nitrate hexahydrate, and 0.186 g of gallium nitrate were added to an aqueous solution and stirred until homogeneous. The molar ratio of divalent metals (nickel, magnesium, cobalt) to trivalent metals (gallium, aluminum) was 3:1. Subsequently, the solution was added dropwise to a 0.5 mol / L sodium carbonate solution, while simultaneously adding sodium hydroxide solution at a concentration of 1 mol / L to maintain the pH at 10. After stirring for 24 h, the sample was collected by filtration, washed with deionized water until neutral, and then dried in a forced-air drying oven at 80 ℃ for 12 h. Finally, it was calcined at 800 ℃ for 5 h in air at a heating rate of 2 ℃ / min to obtain a multi-element composite metal oxide catalyst, wherein the mass fraction of nickel was 10% and the mass fraction of the doped active metals (cobalt, gallium) was 8%.
[0039] The catalyst was loaded into a fixed-bed reactor and reduced for 1 h under a 20% hydrogen atmosphere at a reduction temperature of 750 °C. The reaction temperature was controlled at 700 °C. CO2 and CH4 gases were introduced at chamber pressure with a gas volume ratio of 1:1, and the reaction space velocity was controlled at 35,000 h⁻¹. -1 The steady-state CO2 conversion rate is 83%, the CH4 conversion rate is 80%, and it operates stably for over 200 hours.
[0040] To further characterize the microstructure and dispersion state of the active metal in the catalyst of this invention, the multi-component composite metal oxide catalyst prepared in Example 3 was subjected to transmission electron microscopy (TEM) testing. The results are as follows: Figure 2 and Figure 3 As shown.
[0041] Microscopic images clearly show that dark-colored active metal nanoparticles are densely and uniformly dispersed on a light-colored hydrotalcite-derived carrier matrix. These metal nanoparticles are extremely small in size and highly uniformly distributed, with no obvious aggregation of large metal particles observed throughout the field of view.
[0042] This result confirms that, through a specific co-precipitation in-situ doping method and optimized calcination process, the introduced cobalt and gallium dual-active metals (along with nickel in the matrix) were successfully uniformly dispersed in the composite metal oxide. This highly dispersed microstructure not only maximizes the exposure of catalytic active sites, significantly improving the adsorption and activation efficiency of CO2 and CH4, but also, the strong interaction between the fine metal particles and the matrix greatly inhibits the sintering growth of metal particles and the surface carbonization behavior of the catalyst during high-temperature dry reforming reactions above 700℃. This, from the perspective of microscopic physical structure, provides... Figure 1 The catalyst exhibits exceptionally long stability and excellent conversion rate, providing strong evidence for this.
[0043] Example 4
[0044] A multi-component composite metal oxide catalyst is prepared by the following method:
[0045] 0.883 g of nickel nitrate hexahydrate, 6.030 g of magnesium nitrate hexahydrate, 3.520 g of aluminum nitrate nonahydrate, 0.250 g of cobalt nitrate hexahydrate, and 0.256 g of zinc nitrate hexahydrate were added to an aqueous solution and stirred until homogeneous. The molar ratio of divalent metals (nickel, magnesium, cobalt, and zinc) to trivalent metal (aluminum) was 3:1. Subsequently, the solution was added dropwise to a 0.5 mol / L sodium carbonate solution, while simultaneously adding sodium hydroxide solution at a concentration of 1 mol / L to maintain the pH at 10. After stirring for 24 h, the sample was collected by filtration, washed with deionized water until neutral, and then dried in a forced-air drying oven at 80 ℃ for 12 h. Finally, it was calcined at 800 ℃ for 5 h in air at a heating rate of 2 ℃ / min to obtain a multi-element composite metal oxide catalyst, wherein the mass fraction of nickel was 10% and the mass fraction of doped active metals (cobalt and zinc) was 6%.
[0046] The catalyst was loaded into a fixed-bed reactor and reduced for 1 h under a 20% hydrogen atmosphere at a reduction temperature of 750 °C. The reaction temperature was controlled at 700 °C. CO2 and CH4 gases were introduced at chamber pressure with a gas volume ratio of 1:1, and the reaction space velocity was controlled at 35,000 h⁻¹. -1 The steady-state CO2 conversion rate is 83%, the CH4 conversion rate is 80%, and it operates stably for over 200 hours.
[0047] Comparative Example 1
[0048] A nickel-based hydrotalcite catalyst, the preparation method of which is as follows:
[0049] 0.915 g of nickel nitrate hexahydrate, 6.970 g of magnesium nitrate hexahydrate, and 3.793 g of aluminum nitrate nonahydrate were added to an aqueous solution and stirred until homogeneous. The molar ratio of divalent metals (nickel and magnesium) to trivalent metals (aluminum) was 3:1. The solution was then added dropwise to a sodium carbonate solution while simultaneously adding sodium hydroxide solution dropwise to maintain the pH at 10. The sodium hydroxide solution concentration was 1 mol / L. After stirring for 24 h, the sample was collected by filtration, washed with deionized water until neutral, and then dried in a forced-air drying oven at 80 ℃ for 12 h. Finally, it was calcined at 800 ℃ for 5 h in air at a heating rate of 2 ℃ / min to obtain the nickel-based hydrotalcite catalyst.
[0050] The catalyst was loaded into a fixed-bed reactor and reduced for 1 h under a 20% hydrogen atmosphere at a reduction temperature of 750 °C. The reaction temperature was controlled at 700 °C. CO2 and CH4 gases were introduced at chamber pressure with a gas volume ratio of 1:1, and the reaction space velocity was controlled at 35,000 h⁻¹. -1 At steady state, the CO2 conversion rate was 81% and the CH4 conversion rate was 75%. After 100 hours of operation, the CO2 conversion rate decreased by 6% and the methane conversion rate decreased by 5%.
[0051] Comparative Example 2
[0052] A composite metal oxide catalyst is prepared by the following method:
[0053] 0.931 g of nickel nitrate hexahydrate, 6.956 g of magnesium nitrate hexahydrate, 3.520 g of aluminum nitrate nonahydrate, and 0.186 g of gallium nitrate were added to an aqueous solution and stirred until homogeneous. The molar ratio of divalent metals (nickel and magnesium) to trivalent metals (gallium and aluminum) was 3:1. The solution was then added dropwise to a sodium carbonate solution while simultaneously adding sodium hydroxide solution dropwise to maintain the pH at 10. The sodium hydroxide solution concentration was 1 mol / L. After stirring for 24 h, the sample was collected by filtration, washed with deionized water until neutral, and then dried in a forced-air drying oven at 80 ℃ for 12 h. Finally, the sample was calcined at 800 ℃ for 5 h in air at a heating rate of 2 ℃ / min to obtain the composite metal oxide catalyst.
[0054] The catalyst was loaded into a fixed-bed reactor and reduced for 1 h under a 20% hydrogen atmosphere at a reduction temperature of 750 °C. The reaction temperature was controlled at 700 °C. CO2 and CH4 gases were introduced at chamber pressure with a gas volume ratio of 1:1, and the reaction space velocity was controlled at 35,000 h⁻¹. -1 At steady state, the CO2 conversion rate was 81% and the CH4 conversion rate was 77%. After 100 hours of operation, the CO2 conversion rate decreased by 3% and the methane conversion rate decreased by 4%.
[0055] Comparative Example 3
[0056] A composite metal oxide catalyst is prepared by the following method:
[0057] 0.947 g of nickel nitrate hexahydrate, 6.485 g of magnesium nitrate hexahydrate, 0.518 g of cobalt nitrate hexahydrate, and 3.793 g of aluminum nitrate nonahydrate were added to an aqueous solution and stirred until homogeneous. The molar ratio of divalent metals (nickel, magnesium, and cobalt) to trivalent metals (aluminum) was 3:1. The solution was then added dropwise to a sodium carbonate solution while simultaneously adding sodium hydroxide solution dropwise to maintain the pH at 10. The sodium hydroxide solution concentration was 1 mol / L. After stirring for 24 h, the sample was collected by filtration, washed with deionized water until neutral, and then dried in a forced-air drying oven at 80 °C for 12 h. Finally, the sample was calcined at 800 °C for 5 h in air at a heating rate of 2 °C / min to obtain the composite metal oxide catalyst.
[0058] The catalyst was loaded into a fixed-bed reactor and reduced for 1 h under a 20% hydrogen atmosphere at a reduction temperature of 750 °C. The reaction temperature was controlled at 700 °C. CO2 and CH4 gases were introduced at chamber pressure with a gas volume ratio of 1:1, and the reaction space velocity was controlled at 35,000 h⁻¹. -1 At steady state, the CO2 conversion rate was 83% and the CH4 conversion rate was 76%. After 100 h of operation, the CO2 conversion rate decreased by 2% and the methane conversion rate decreased by 2%.
[0059] Results Analysis
[0060] Comparing Example 3 and Comparative Example 1, it is evident that, under identical conditions, this invention significantly enhances the reaction activity and lifetime of the catalyst by introducing cobalt and gallium into the Ni-Mg-Al system to form a multi-component composite metal oxide, compared to the undoped nickel-based layered double hydroxide catalyst. Data from Comparative Example 1 shows that the basic nickel-based catalyst exhibits steady-state CO2 and CH4 conversion rates of 81% and 75%, respectively, and shows significant deactivation after 100 hours (conversion rates decreased by 6% and 5%, respectively), indicating insufficient resistance to carbon deposition and sintering. In contrast, the multi-component composite metal oxide catalyst prepared in Example 3 not only increased the steady-state CO2 and CH4 conversion rates to 84% and 80%, respectively, but also achieved stable operation for over 200 hours without significant activity decay. This demonstrates that the introduction of cobalt and gallium effectively modulates the surface electronic structure or active site distribution of the catalyst, overcoming the technical deficiency of traditional nickel-based catalysts' susceptibility to deactivation in high-temperature dry reforming reactions, and significantly enhancing the catalyst's industrial application potential.
[0061] Comparing Example 3 with Comparative Example 2 (single-gallium doping) and Comparative Example 3 (single-cobalt doping), it can be seen that the cobalt-gallium bimetallic synergistic doping strategy adopted in this invention produced unexpected technical effects, with performance significantly superior to single-metal doping. Although Comparative Example 2 and Comparative Example 3 improved catalyst performance to some extent, their highest methane conversion rate was only 77% (Comparative Example 2), and after 100 h of operation, there was still a 2% to 4% decrease in activity, indicating that it is difficult to simultaneously achieve high activity and ultra-long-term stability by introducing a single active component. In contrast, Example 3, after simultaneously introducing cobalt and gallium, significantly increased the CH4 conversion rate to 80%, and extended the stable operating time to over 200 h, far exceeding the single-doped system. This confirms that cobalt and gallium in the catalytic system are not simply functionally superimposed, but rather, through the interaction between the two components, a synergistic enhancement mechanism may be formed in promoting methane CH bond activation and inhibiting carbon deposition, thereby enabling the obtained multi-component composite catalyst to exhibit the best catalytic reforming performance.
[0062] To further verify the deactivation resistance of the catalyst of this invention, a long-term stability test was conducted using the multi-component composite metal oxide catalyst prepared in Example 3 (cobalt and gallium dual doping) as an example. The test results are as follows: Figure 1 As shown.
[0063] Combination Figure 1 It can be seen that during the continuous reaction test lasting more than 140 hours, the catalytic activity of the catalyst did not show any obvious signs of decline. Specifically, the CO2 conversion rate remained stable between 83% and 84%, the CH4 conversion rate remained around 80%, and the H2 / CO ratio in the product syngas remained stably above 0.9.
[0064] The above curve results fully demonstrate that this invention, by in-situ introducing specific bimetallic compounds (such as cobalt-gallium, cobalt-iron, etc.) into the nickel-magnesium-aluminum layered double hydroxide precursor for synergistic doping, successfully constructs abundant oxygen vacancies and enhanced basicity sites on the surface of multi-component composite metal oxides. This unique microstructure effectively regulates the dynamic balance between carbon deposition and carbon removal processes, avoiding CH4 formation. x The accumulation of species on the catalyst surface overcomes the technical defect of traditional nickel-based catalysts that are prone to rapid deactivation due to surface carbonization and sintering in high-temperature dry reforming reactions, thus achieving stable operation over an ultra-long period and having broad prospects for industrial application.
Claims
1. A multi-component composite metal oxide catalyst, characterized in that, The catalyst is prepared by calcining a precursor with a hydrotalcite structure, wherein the precursor is nickel-magnesium-aluminum hydrotalcite doped with an active metal; wherein, based on the total mass of the multi-component composite metal oxide catalyst, the mass fraction of nickel is 6%-12%; the active metal is two of cobalt, copper, zinc, iron, gallium, and cerium, and the total mass fraction of the active metal is 2%-10% based on the total mass of the multi-component composite metal oxide catalyst. The active metal is in situ doped into the nickel-magnesium-aluminum hydrotalcite and uniformly dispersed in the multi-component composite metal oxide catalyst in the form of a solid solution.
2. The multi-component composite metal oxide catalyst according to claim 1, characterized in that, The active metal is a combination of two metals, selected from a combination of cobalt and iron, a combination of copper and cerium, a combination of cobalt and gallium, or a combination of cobalt and zinc.
3. A method for preparing a multi-component composite metal oxide catalyst as described in claim 1 or 2, characterized in that, The method includes the following steps: S1, dissolving a nickel source, a magnesium source, an aluminum source, and the metal salt corresponding to the active metal in water and mixing them evenly to obtain a metal salt mixed solution; S2, adding the metal salt mixed solution dropwise to a sodium carbonate solution while simultaneously adding an alkaline solution to maintain the pH of the reaction system at a constant 9-10, and stirring the reaction at a temperature of 60-75°C to obtain a coprecipitated product; S3, collecting the coprecipitated product after the reaction by filtration, washing it with deionized water until neutral, and then drying it to obtain the precursor with a hydrotalcite structure; S4, calcining the precursor in an air atmosphere to obtain the multi-component composite metal oxide catalyst.
4. The preparation method according to claim 3, characterized in that, In step S1, the molar ratio of divalent metal to trivalent metal in the metal salt mixed solution is 2-3.5:
1.
5. The preparation method according to claim 3, characterized in that, In step S1, the nickel source, magnesium source, aluminum source and the metal salt corresponding to the active metal are all nitrates; in step S2, the alkaline solution is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 0.5-2 mol / L.
6. The preparation method according to claim 3, characterized in that, In step S2, the concentration of the sodium carbonate solution is 0.3-0.8 mol / L.
7. The preparation method according to claim 3, characterized in that, In step S3, the drying temperature is 80℃ and the drying time is 12h; in step S4, the calcination temperature is 750-900℃ and the calcination time is 3-6h, with a heating rate of 2℃ / min.
8. The application of a multi-component composite metal oxide catalyst as described in claim 1 or 2 in the dry reforming reaction of carbon dioxide and methane.
9. The application according to claim 8, characterized in that, Includes the following steps: The multi-component composite metal oxide catalyst was loaded into a fixed-bed reactor and reduced under a hydrogen atmosphere with a volume fraction of 5%-30%, with the reduction temperature controlled at 650-750℃. After reduction, a dry reforming reaction is carried out by introducing carbon dioxide and methane gases at a reaction temperature of 600-800℃, with the reaction space velocity controlled at 5000 h⁻¹. -1 Up to 100,000 h -1 .
10. The application according to claim 9, characterized in that, The volume ratio of carbon dioxide gas to methane gas is 1:1; the reduction treatment time is 1 hour.