LDO catalyst for efficient CO2 methanation reaction and preparation method of LDO catalyst

Abstract

The invention discloses an LDO catalyst for an efficient CO2 methanation reaction and a preparation method thereof.The preparation method comprises the following steps that NiAlLDH of a hydrotalcite structure serves as a precursor, in-situ topological transformation is conducted in the hydrogen reducing atmosphere, and the LDO catalyst for the efficient CO2 methanation reaction is obtained. Meanwhile, full-spectrum response and a good photothermal effect are achieved.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation and photothermal carbon dioxide conversion, and relates to an LDO catalyst for efficient CO2 methanation reaction and its preparation method. Background Technology

[0002] With the increasing severity of resource shortages and global climate change, carbon dioxide (CO2) capture, utilization, and storage technologies have attracted widespread attention. Among these, CO2 methanation can convert greenhouse gases into high-value fuel methane (CH4), thereby achieving carbon resource recycling and possessing significant environmental and economic value. In particular, utilizing clean solar energy and coupling the synergistic effect of light and heat energy can significantly reduce the reaction activation energy under medium-low temperature conditions (150–350 °C), achieving highly efficient CO2 conversion and utilization. Furthermore, by controlling photogenerated carriers to optimize the reaction pathway, photothermal catalytic CO2 methanation shows broad application prospects.

[0003] However, in existing research, the performance of widely used supported nickel-based materials is limited by problems such as poor high-temperature stability, low methane selectivity, and insufficient dispersion of active sites. The weak metal-support interaction of traditional Ni / Al₂O₃ catalysts often fails to effectively anchor metal particles, and the agglomeration and sintering of Ni nanoparticles during high-temperature reactions can lead to rapid deactivation of active sites. Furthermore, catalysts prepared by impregnation or co-precipitation methods also suffer from uneven metal particle distribution and a wide range of particle sizes; excessively large Ni particles cannot effectively participate in the reaction, resulting in low utilization of active sites. To improve these shortcomings, researchers have attempted to enhance performance through noble metal modification (such as Pt, Ru) or complex structural designs (such as core-shell confinement and mesoporous encapsulation). However, the use of noble metals significantly increases the technological cost, and overly complex catalyst preparation processes are difficult to meet industrial-scale requirements. Therefore, based on photothermal catalysis, improving the stability, selectivity, and active site utilization of Ni-based catalysts is an ideal strategy for achieving efficient and large-scale CO₂ conversion and utilization.

[0004] In recent years, layered bimetallic hydroxides (LDHs) have shown great potential in the field of catalysis due to their tunable layered structure and highly uniform dispersion of active sites. In-situ topological transformations induced by calcination can convert LDHs into complex metal oxides (LDOs). Their unique confinement effect and high-density oxygen vacancies can anchor ultrafine metal active centers (1-3 nm), while their tunable surface acidity / basicity sites can optimize the adsorption and activation pathways of reactant molecules. LDHs have demonstrated excellent performance as supported catalyst precursors in various hydrogenation and oxidation reactions. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an LDO catalyst for efficient CO2 methanation reaction and its preparation method. The LDO catalyst prepared by this method has stability and selectivity, as well as full-spectrum response and good photothermal effect.

[0006] To achieve the above objectives, this invention discloses a method for preparing an LDO catalyst for a highly efficient CO2 methanation reaction, comprising the following steps: using NiAlLDH with a hydrotalcite structure as a precursor, the LDO catalyst for the highly efficient CO2 methanation reaction is obtained by in-situ topological transformation under a hydrogen reducing atmosphere.

[0007] Furthermore, the specific steps include: 1) Obtaining NiAlLDH catalyst precursor; 2) The NiAlLDH catalyst precursor is reduced in situ in a fixed-bed reactor and then cooled to room temperature in an inert N2 atmosphere to obtain LDO-T, an LDO catalyst for efficient CO2 methanation reaction, where T represents the reduction temperature in the in situ reduction process.

[0008] Furthermore, in step 2), the heating rate during the in-situ reduction process is 10 °C / min, the reducing atmosphere is 100 mL / min H2, and the in-situ reduction time is 1 h.

[0009] Furthermore, in step 2), the reduction temperature is 100-800 °C.

[0010] Further, the specific process of step 1) is as follows: nickel nitrate hexahydrate, aluminum nitrate nonahydrate, polyvinylpyrrolidone and urea are dissolved in ultrapure water and stirred at room temperature to obtain a mixture. The mixture is then subjected to a hydrothermal reaction. Finally, after centrifugation, washing and drying, the NiAlLDH catalyst precursor is obtained.

[0011] Furthermore, the stirring time at room temperature is 30 minutes; The hydrothermal reaction was carried out at a temperature of 100℃ for 10 hours.

[0012] Furthermore, the ratio of ultrapure water, nickel nitrate hexahydrate, aluminum nitrate nonahydrate, polyvinylpyrrolidone, and urea is 150 mL: 2.71 g: 1.72 g: 0.5 g: 2 g.

[0013] Furthermore, by promoting defect repair through hydrothermal reaction conditions, layered NiAlLDH nanosheets with high crystallinity and tunable structure are formed. At the same time, polyvinylpyrrolidone is added as a stabilizer and morphology control agent, and the steric hindrance effect of PVP molecules is used to inhibit particle aggregation.

[0014] Furthermore, by adjusting the reduction temperature, Ni with different degrees of reduction was obtained. 0 / NiO interface structure, regulating the reaction activity of catalyst.

[0015] This invention discloses an LDO catalyst for a highly efficient CO2 methanation reaction, which is prepared based on the method for preparing the LDO catalyst for a highly efficient CO2 methanation reaction.

[0016] The present invention has the following beneficial effects: The LDO catalyst for efficient CO2 methanation reaction and its preparation method described in this invention involve preparing layered metal hydroxides via a hydrothermal method, and embedding N2 in the LDH layers. 2+ This invention utilizes the dispersed morphology of layered nanosheets, the reducing power of metal ions, and the anchoring effect of oxygen vacancies on metals to achieve the construction of highly dispersed small-sized Ni nanoclusters. Simultaneously, by adjusting the reduction temperature to control the Ni / NiO interface anchored on the Al2O3 support, excellent catalytic performance with 99.5% methane selectivity and high methane yield is achieved in the photothermal catalytic CO2 reaction. Furthermore, this invention uses inexpensive metal salts such as nickel nitrate and aluminum nitrate as raw materials to prepare high-purity, uniformly morphological, and large-specific-surface-area hydrotalcite nanosheets via a modified hydrothermal method. Further in-situ reduction yields uniformly sized and highly dispersed Ni nanoclusters. The entire synthesis process is easy to operate and can be scaled up, making it a low-cost catalyst preparation process that can be extended to the preparation of other similar metal catalysts. Testing showed that the LDO catalyst obtained by this invention has a particle size of 170.4 μm. 2 The LDO catalyst obtained in this invention exhibits excellent reactivity in the photothermal CO2 methanation reaction, with a high specific surface area of ​​ / g and small, highly dispersed Ni nanoclusters of 2.12 nm as active sites. -1 ·g cat -1 The CH4 selectivity is 95%, and the catalytic activity shows no significant change after a long reaction time of 20 h, indicating good stability. Furthermore, with the same feedstock amounts, the CH4 yield of the LDO catalyst obtained in this invention in the photothermal CO2 methanation reaction is approximately 1.55 to 1.94 times that of the Ni / Al2O3 comparative catalyst. Finally, the LDO catalyst described in this invention has a relatively simple preparation process and low preparation cost, and coupled with photothermal catalysis, it can achieve a relatively high level of catalytic activity for CO2 methanation currently in the field. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 The XRD patterns of the catalysts obtained in Example 1, Example 2 and Comparative Example 1 are shown below. Figure 2 TEM images of the catalysts obtained in Example 1, Example 2, and Comparative Example 1; Figure 3 The BET diagrams are for the catalysts obtained in Example 1, Example 2, and Comparative Example 1. Figure 4 The graph shows the CO2 methanation performance of the catalysts obtained in Examples 1, 2 and Comparative Example 1 under photothermal reaction conditions. In the graph, A is the CO2 conversion rate; B is the CH4 selectivity; C is the CH4 yield; D is the catalyst stability after 20 h. The reaction temperature is 330 °C, the feed gas CO2:H2:N2 = 1:4:3, and the total flow rate is 80 mL / min. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0020] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0021] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0022] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0023] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0024] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0027] Example 1 The preparation method of the LDO catalyst for efficient CO2 methanation reaction according to the present invention includes the following steps: 1) Dissolve 2.71 g of nickel nitrate hexahydrate, 1.72 g of aluminum nitrate nonahydrate, 0.5 g of polyvinylpyrrolidone, and 2 g of urea in 150 mL of ultrapure water and stir at room temperature for 30 min. Then transfer the mixture to a stainless steel hydrothermal reactor and hydrothermally react at 100 °C for 10 h. Finally, after centrifugation, washing, and drying, the solid obtained is the NiAlLDH catalyst (NiAlLDH catalyst precursor).

[0028] 2) The NiAlLDH catalyst was heated to 800 °C in a fixed-bed reactor at a rate of 10 °C / min and reduced in situ for 1 h. The reduction atmosphere was hydrogen gas at a rate of 100 mL / min. After the reduction was completed, the catalyst was cooled to room temperature in a nitrogen inert gas atmosphere to obtain the LDO-500 catalyst.

[0029] The LDO-500 catalyst obtained in step 2) was used for photothermal catalytic CO2 methanation reaction. The product components were detected by gas chromatography, and the CO2 conversion, CH4 yield and CH4 selectivity were calculated.

[0030] Figure 1 The marked curves are XRD patterns of NiAlLDH and LDO-500 catalysts. Figure 2 -A is a TEM image of the NiAlLDH catalyst. Figure 2 -B is a TEM image of the LDO-500 catalyst. Figure 3 The marked curves are BET plots of NiAlLDH and LDO-500 catalysts. Figure 4 The labeled curve represents the photothermal CO2 methanation activity test results of the LDO-500 catalyst.

[0031] Depend on Figure 1 The XRD patterns show that the NiAlLDH precursor was successfully prepared, and the prepared hydrotalcite has high purity with no impurity diffraction peaks. The LDO-500 catalyst was also successfully prepared, exhibiting diffraction peaks for Ni, NiO, and Al2O3 simultaneously at 500 °C. Figure 2 The TEM image of -A shows that the layered NiAlLDH nanosheet catalyst was successfully prepared, and the nanosheets are relatively uniform and well dispersed. (See attached image.) Figure 2 TEM images of layered LDO-500 nanosheet catalyst (-B) show that the catalyst was successfully prepared, with relatively uniform nanosheets and good dispersion. Obvious Ni nanoclusters precipitated at 500 °C, and the nanoclusters exhibited relatively consistent particle size and high uniform dispersion. Figure 3 The BET curve and calculation results show that the specific surface area of ​​the NiAlLDH precursor is 93.4 m². 2 / g, pore size 5.27 nm. The specific surface area of ​​the LDO-500 catalyst is 170.4 m². 2 With a surface area of ​​ / g and a pore size of 2.12 nm, this is the catalyst sample with the largest specific surface area and smallest pore size among the examples and comparative examples. Figure 4 The photothermal CO2 methanation activity test results show that at 330 °C, the LDO-500 catalyst exhibits a CO2 conversion rate of 84.5%, a CH4 selectivity of 99.5%, and a CH4 yield of 654.2 mmol·h⁻¹. -1 ·g cat -1 The catalyst exhibits good stability, with methane yield and selectivity remaining stable within 20 hours.

[0032] Example 2 The preparation method of the LDO catalyst for efficient CO2 methanation reaction according to the present invention includes the following steps: 1) Dissolve 2.71 g of nickel nitrate hexahydrate, 1.72 g of aluminum nitrate nonahydrate, 0.5 g of polyvinylpyrrolidone, and 2 g of urea in 150 mL of ultrapure water and stir at room temperature for 30 min. Then transfer the liquid to a stainless steel hydrothermal reactor and hydrothermally react at 100 °C for 10 h. Finally, after centrifugation, washing, and drying, the solid obtained is the NiAlLDH catalyst (NiAlLDH catalyst precursor).

[0033] 2) The NiAlLDH catalyst was heated to 800 °C in a fixed-bed reactor at a rate of 10 °C / min and reduced in situ for 1 h. The reduction atmosphere was hydrogen gas at a rate of 100 mL / min. After the reduction was completed, the catalyst was cooled to room temperature in a nitrogen inert gas atmosphere to obtain the LDO-800 catalyst.

[0034] The LDO-800 catalyst obtained in step 2) was used for photothermal catalytic CO2 methanation reaction. The product components were detected by gas chromatography, and the CO2 conversion, CH4 yield and CH4 selectivity were calculated.

[0035] Figure 1 The marked curve is the XRD pattern of the LDO-800 catalyst. Figure 2 -C is a TEM image of the LDO-800 catalyst. Figure 3 The marked curve is the BET plot of the LDO-800 catalyst. Figure 4 The labeled curve represents the photothermal CO2 methanation activity test results of the LDO-800 catalyst.

[0036] Depend on Figure 1The XRD curves show that the LDO-800 catalyst was successfully prepared. At 800 °C, diffraction peaks for Ni, NiO, and Al2O3 were simultaneously present, with more pronounced in-situ reduction and precipitation of Ni. (See attached image.) Figure 2 TEM images at -C show that the layered LDO-800 nanosheet catalyst was successfully prepared, but the nanosheets are not very dispersed and have some stacking. More obvious Ni nanoclusters precipitate at 800 °C, but the dispersion is not uniform, and there is aggregation of large Ni clusters. Figure 3 The BET curve and calculation results show that the specific surface area of ​​the LDO-800 catalyst is 97.9 m². 2 / g, pore size 2.4 nm. (From) Figure 4 The photothermal CO2 methanation activity test results show that at 330 °C, the LDO-800 catalyst exhibits a CO2 conversion rate of 73.7%, a CH4 selectivity of 98%, and a CH4 yield of 556.5 mmol·h⁻¹. -1 ·g cat -1 The catalyst exhibits good stability, with methane yield and selectivity remaining stable within 20 hours.

[0037] Comparative Example 1 This comparative example includes the following steps: 1) Dissolve 2.71 g of nickel nitrate hexahydrate, 1.72 g of aluminum nitrate nonahydrate, and aluminum nitrate in 200 mL of ultrapure water. Adjust the pH of the solution to 8-10 with ammonia and stir at room temperature for 3 h to achieve co-precipitation. Finally, after centrifugation, washing, and drying, the solid obtained is Ni-Al₂O. 3- CP catalyst precursor.

[0038] 2) The above-mentioned Ni-Al2O3-CP catalyst precursor was heated to 500 °C in a muffle furnace at a rate of 5 °C / min and kept calcined for 2 h. Then, it was heated to 500 °C in a fixed bed reactor at a rate of 10 °C / min and reduced in situ for 1 h. The reducing atmosphere was hydrogen gas at a rate of 100 mL / min. After the reduction was completed, it was cooled to room temperature in a nitrogen inert gas atmosphere to obtain the Ni-Al2O3-CP catalyst.

[0039] The Ni-Al2O3-CP catalyst obtained in step 2) was used for photothermal catalytic CO2 methanation reaction. The product components were detected by gas chromatography, and the CO2 conversion, CH4 yield and CH4 selectivity were calculated.

[0040] Figure 1 The labeled curve in the figure is the XRD pattern of the Ni-Al2O3-CP catalyst. Figure 2 -D is a TEM image of the Ni-Al2O3-CP catalyst. Figure 3The marked curve is the BET plot of the Ni-Al2O3-CP catalyst. Figure 4 The labeled curves represent the results of the photothermal CO2 methanation activity test of the Ni-Al2O3-CP catalyst.

[0041] Depend on Figure 1 The XRD curves show that the Ni-Al2O3-CP catalyst was successfully prepared. Figure 2 TEM images of -D show that the Ni-Al2O3-CP catalyst was successfully prepared. However, the Al2O3-supported Ni catalyst prepared by the co-precipitation method exhibits severe agglomeration and stacking. The reduced Ni clusters have varying particle sizes and are extremely unevenly distributed on the support, which affects the adsorption and activation of reactant molecules. Figure 3 The BET curve and calculation results show that the specific surface area of ​​the Ni-Al2O3-CP catalyst is 6.2 m². 2 With a surface area of ​​ / g and a pore size of 10.62 nm, it is evident that co-precipitation preparation of high-load Ni catalysts often suffers from defects such as small specific surface area and insufficient uniform dispersion. Figure 4 The photothermal CO2 methanation activity test results showed that although the initial reaction performance was moderate, the stability of the control catalyst was very poor, and the methane yield and selectivity decreased almost linearly with the extension of reaction time. After 20 h of operation, the CO2 conversion rate of the Ni-Al2O3-CP catalyst dropped sharply from 73.5% to 65.2%, the CH4 selectivity dropped sharply from 94.2% to 87.5%, and the CH4 yield dropped sharply from 421.5 mmol·h⁻¹. -1 ·g cat -1 It dropped sharply to 337.6 mmol·h -1 ·g cat -1 .

[0042] Example 3 The preparation method of the LDO catalyst for efficient CO2 methanation reaction according to the present invention includes the following steps: 1) Obtaining NiAlLDH catalyst precursor; 2) The NiAlLDH catalyst precursor is reduced in situ in a fixed-bed reactor and then cooled to room temperature in an inert N2 atmosphere to obtain LDO-T, an LDO catalyst for efficient CO2 methanation reaction, where T represents the reduction temperature in the in situ reduction process.

[0043] Furthermore, in step 2), the heating rate during the in-situ reduction process is 10 °C / min, the reducing atmosphere is 100 mL / min H2, and the in-situ reduction time is 1 h.

[0044] Furthermore, in step 2), the reduction temperature is 100 °C.

[0045] Further, the specific process of step 1) is as follows: nickel nitrate hexahydrate, aluminum nitrate nonahydrate, polyvinylpyrrolidone and urea are dissolved in ultrapure water and stirred at room temperature to obtain a mixture. The mixture is then subjected to a hydrothermal reaction. Finally, after centrifugation, washing and drying, the NiAlLDH catalyst precursor is obtained.

[0046] Furthermore, the stirring time at room temperature is 30 minutes; The hydrothermal reaction was carried out at a temperature of 100℃ for 10 hours.

[0047] Furthermore, the ratio of ultrapure water, nickel nitrate hexahydrate, aluminum nitrate nonahydrate, polyvinylpyrrolidone, and urea is 150 mL: 2.71 g: 1.72 g: 0.5 g: 2 g.

[0048] This invention proposes a modified hydrothermal method for preparing layered metal hydroxide (NiAlLDH) precursors. Precise construction of active sites is achieved through one-step controllable calcination, resulting in an LDO catalyst that exhibits synergistic optimization of both stability and selectivity. Furthermore, the interface-controlled design strategy enables the catalyst to possess a full-spectrum response and excellent photothermal effect, further advancing its practical application in photothermal catalytic CO2 methanation.

[0049] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0050] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0051] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing an LDO catalyst for a highly efficient CO2 methanation reaction, characterized in that, Includes the following steps: Using NiAlLDH with a hydrotalcite structure as a precursor, the LDO catalyst for efficient CO2 methanation reaction was obtained by in-situ topological transformation under a hydrogen reducing atmosphere.

2. The method for preparing the LDO catalyst for efficient CO2 methanation reaction according to claim 1, characterized in that, Specifically, the following steps are included: 1) Obtaining NiAlLDH catalyst precursor; 2) The NiAlLDH catalyst precursor is reduced in situ in a fixed-bed reactor and then cooled to room temperature in an inert N2 atmosphere to obtain LDO-T, an LDO catalyst for efficient CO2 methanation reaction, where T represents the reduction temperature in the in situ reduction process.

3. The method for preparing the LDO catalyst for efficient CO2 methanation reaction according to claim 2, characterized in that, In step 2), the heating rate during the in-situ reduction process is 10 °C / min, the reducing atmosphere is 100 mL / min H2, and the in-situ reduction time is 1 h.

4. The method for preparing the LDO catalyst for efficient CO2 methanation reaction according to claim 2, characterized in that, In step 2), the reduction temperature is 100-800 °C.

5. The method for preparing the LDO catalyst for efficient CO2 methanation reaction according to claim 2, characterized in that, The specific process of step 1) is as follows: nickel nitrate hexahydrate, aluminum nitrate nonahydrate, polyvinylpyrrolidone and urea are dissolved in ultrapure water and stirred at room temperature to obtain a mixture. The mixture is then subjected to a hydrothermal reaction. Finally, after centrifugation, washing and drying, the NiAlLDH catalyst precursor is obtained.

6. The method for preparing the LDO catalyst for efficient CO2 methanation reaction according to claim 5, characterized in that, Stirring at room temperature for 30 minutes; The hydrothermal reaction was carried out at a temperature of 100℃ for 10 hours.

7. The method for preparing the LDO catalyst for efficient CO2 methanation reaction according to claim 5, characterized in that, The ratio of ultrapure water, nickel nitrate hexahydrate, aluminum nitrate nonahydrate, polyvinylpyrrolidone, and urea is 150 mL: 2.71 g: 1.72 g: 0.5 g: 2 g.

8. The method for preparing the LDO catalyst for efficient CO2 methanation reaction according to claim 2, characterized in that, Defect repair is promoted through hydrothermal reaction conditions to form layered NiAlLDH nanosheets with high crystallinity and tunable structure. At the same time, polyvinylpyrrolidone (PVP) is added as a stabilizer and morphology control agent to inhibit particle agglomeration by utilizing the steric hindrance effect of PVP molecules.

9. The method for preparing the LDO catalyst for efficient CO2 methanation reaction according to claim 2, characterized in that, By adjusting the reduction temperature, Ni with different degrees of reduction was obtained. 0 / NiO interface structure, regulating the reaction activity of catalyst.

10. An LDO catalyst for efficient CO2 methanation reaction, characterized in that, It was prepared according to the method for preparing the LDO catalyst for efficient CO2 methanation reaction as described in any one of claims 1-9.

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