An adsorption-enhanced nickel-based catalyst, its preparation method, and its application in low-temperature CO2 methanation.

Abstract

This invention discloses an adsorption-enhanced nickel-based catalyst, its preparation method, and its application in low-temperature CO2 methanation, belonging to the field of low-temperature CO2 methanation catalyst preparation technology. The adsorption-enhanced nickel-based catalyst of this invention uses mesoporous yttrium oxide as a support and metallic nickel salt as the active component. The mass content of mesoporous yttrium oxide is 80.0–95.0 wt%, and the mass content of metallic nickel salt is 5.0–20.0 wt%. This invention also discloses the preparation method and application of the above-mentioned adsorption-enhanced nickel-based catalyst. By constructing a mesoporous yttrium oxide-confined nickel nanoparticle structure, this invention enhances the adsorption capacity of reactant CO2 and key intermediate CO, significantly improving the low-temperature CO2 methanation performance of the nickel-based catalyst. At a low temperature of 240℃, the CO2 conversion rate reaches 65%, and the CH4 selectivity is 100%, while also exhibiting excellent stability.

Description

Technical Field

[0001] This invention belongs to the field of low-temperature CO2 methanation catalyst preparation technology, specifically relating to an adsorption-enhanced nickel-based catalyst, its preparation method, and its application in low-temperature CO2 methanation. Background Technology

[0002] CO2 methanation is a crucial route for CO2 capture, utilization, and storage. The resulting methane can be easily separated and integrated into existing natural gas pipelines for transportation and use. Given the highly volatile nature of green hydrogen production and the significant challenges in hydrogen storage and transportation, converting hydrogen into methane for storage and transport is a promising technology. CO2 methanation can simultaneously achieve large-scale CO2 emission reduction and H2 storage, and the produced methane can also reduce dependence on imported natural gas to some extent, alleviating my country's natural gas resource shortage. CO2 methanation is a strongly exothermic reaction, while the side reaction—the reverse water-gas shift reaction—is endothermic. Therefore, low temperatures are beneficial for highly active and selective methane production. Furthermore, nickel salts are prone to sintering at high temperatures, leading to poor catalyst stability.

[0003] To improve the low-temperature performance and stability of catalysts, it is necessary to rationally design the active metal and support in the catalyst. For the CO2 methanation reaction, the size of the active metal nickel salt directly affects the adsorption strength of the intermediate CO, and the CO adsorption strength is the key to evaluating catalytic activity. Although small-sized nickel has more reaction sites, CO adsorption is weaker, and the product is mainly CO. As the size of nickel increases, CO adsorption gradually increases, and the product becomes mainly methane. Therefore, medium-sized nickel salts with both more reaction sites and stronger CO adsorption are key to achieving efficient CO2 to methane production. In addition, the support effect and strong metal-support interaction also play an important role in the CO2 hydrogenation process. The support can not only promote the dispersion of active metals and provide sufficient active sites, but also regulate the adsorption strength of CO2 on the catalyst surface, thereby controlling the CO2 activation ability.

[0004] In view of this, in order to overcome the shortcomings of the prior art, it is necessary to provide a low-temperature nickel-based CO2 methanation catalyst, in order to simultaneously improve the adsorption strength of reactant CO2 and intermediate CO on the catalyst surface, thereby improving the low-temperature CO2 methanation performance. Summary of the Invention

[0005] One of the objectives of this invention is to provide an adsorption-enhanced nickel-based catalyst.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: an adsorption-enhanced nickel-based catalyst, wherein the adsorption-enhanced nickel-based catalyst uses mesoporous yttrium oxide as a support and metallic nickel salt as the active component, wherein the mass content of the mesoporous yttrium oxide is 80.0–95.0 wt%, and the mass content of the metallic nickel salt is 5.0–20.0 wt%.

[0007] The principle of the adsorption-enhanced nickel-based catalyst of the present invention is as follows:

[0008] The content of nickel salt and mesoporous yttrium oxide affects the activity of nickel-based catalysts and the nanoscale size of the nickel salt. Insufficient nickel salt content results in fewer active sites and weak adsorption performance, leading to low catalytic activity. Conversely, excessive nickel salt content tends to aggregate on the surface of mesoporous yttrium oxide, forming excessively large particles that reduce reaction sites and further decrease activity. Extensive experiments have demonstrated that the adsorption-enhanced nickel-based catalyst obtained when the mesoporous yttrium oxide and nickel salt are at the aforementioned mass ratios exhibits the best technical performance, demonstrating excellent low-temperature CO2 methanation performance. At 240℃, the CO2 conversion rate reaches 65%, and the CH4 selectivity is 100%, while also possessing excellent stability.

[0009] The beneficial effects of the adsorption-enhanced nickel-based catalyst of the present invention are:

[0010] 1. This invention uses mesoporous yttrium oxide as a support. By adjusting the amount of metallic nickel salt and mesoporous yttrium oxide, and by using the confinement effect of mesoporous yttrium oxide, the particle size of metallic nickel salt can be controlled, thereby achieving a high CO2 conversion rate of the adsorption-enhanced nickel-based catalyst at low temperatures.

[0011] 2. The adsorption-enhanced nickel-based catalyst of the present invention has excellent low-temperature CO2 methanation performance, achieving a CO2 conversion rate of 65% and a CH4 selectivity of 100% at a low temperature of 240℃, while also exhibiting excellent stability.

[0012] Based on the above technical solution, the present invention can be further improved as follows.

[0013] Furthermore, the mesoporous yttrium oxide has an average pore size of 8.2 nm and a pore volume of 0.54 cm³. 3 / g, specific surface area is 184m² 2 / g; the particle size of the nickel salt is 8.0-9.0nm.

[0014] The further beneficial effects of the above-mentioned method are: mesoporous yttrium oxide, with its confined nickel nanoparticle structure, enhances the adsorption capacity of reactant CO2 and key intermediate CO, significantly improving the low-temperature CO2 methanation performance of nickel-based catalysts. Mesoporous yttrium oxide has a large specific surface area and a porous structure, which promotes uniform nickel dispersion. The porous confinement effect restricts the size of nickel metal nanoparticles, allowing for better control of nickel metal size.

[0015] Furthermore, the particle size of the adsorption-enhanced nickel-based catalyst is 10-200 mesh.

[0016] The second objective of this invention is to provide a method for preparing the above-mentioned adsorption-enhanced nickel-based catalyst.

[0017] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: the preparation method of the above-mentioned adsorption-enhanced nickel-based catalyst includes the following steps:

[0018] S1: Preparation of mesoporous yttrium oxide support

[0019] S11: Weigh yttrium salt, dissolve it in ethanol, and stir thoroughly at room temperature to obtain a first homogeneous solution; add mesoporous silica to the first homogeneous solution, stir at room temperature for 0.5-1 h, then stir in a water bath at 30-40°C to completely evaporate the ethanol, and then calcine in air at 500-600°C for 5-7 h to obtain a white solid;

[0020] S12: The obtained white solid was transferred to sodium hydroxide solution and stirred continuously in a water bath for 12-24 hours. It was then centrifuged and washed with deionized water, and repeated 3-5 times. The precipitate obtained by centrifugation was dried at 100-120℃ for 12-24 hours to obtain mesoporous yttrium oxide support.

[0021] S2: Preparation of precursors

[0022] Weigh out a nickel salt, dissolve it in deionized water, and stir thoroughly at room temperature to obtain a second homogeneous solution; slowly add the mesoporous yttrium oxide support obtained in step S1 to the second homogeneous solution, stir to mix it evenly, allow it to age at room temperature, dry it at 100-120°C for 12-24 hours, and calcine it in air atmosphere for 3-5 hours to obtain the precursor;

[0023] S3: Precursor Restoration

[0024] The precursor obtained from S2 was reduced at atmospheric pressure under a hydrogen atmosphere at 300–600 °C for 4–10 h to obtain an adsorption-enhanced nickel-based catalyst.

[0025] The principle of the preparation method of the adsorption-enhanced nickel-based catalyst of the present invention is as follows:

[0026] In step S1 of the present invention, ethanol is selected as the solvent, which can effectively diffuse yttrium salt on the surface of mesoporous silica, thereby forming a porous yttrium oxide structure, and is also beneficial for water bath stirring and evaporation.

[0027] In step S2 of the present invention, static aging is beneficial for the deposition and dispersion of metallic nickel salt on porous yttrium oxide, and the reduced metallic nickel salt is more uniformly dispersed with more reaction sites.

[0028] The stability test results of the adsorption-enhanced nickel-based catalyst obtained in step S3 of this invention are as follows: stable operation for 125 hours, CO2 conversion rate maintained at around 80%, methane selectivity 100%, reaction temperature 300℃, and pressure 0.1 MPa. This indicates that the adsorption-enhanced nickel-based catalyst obtained in this invention maintains good stability even at a high temperature of 300℃ and achieves a high conversion rate at low temperatures. In contrast, most current catalysts require temperatures of 300℃ or higher to achieve high CO2 methanation activity.

[0029] In summary, the present invention, through the above preparation method, can achieve a CO2 methanation process with high conversion rate, high selectivity, and high stability under mild conditions, and the obtained adsorption-enhanced nickel-based catalyst has high stability.

[0030] The beneficial effects of the preparation method of the adsorption-enhanced nickel-based catalyst of the present invention are:

[0031] This invention enables a CO2 methanation process with high conversion rate, high selectivity, and high stability under mild conditions. The resulting adsorption-enhanced nickel-based catalyst exhibits high stability, is simple to operate, low in cost, and has broad market prospects, making it suitable for large-scale application.

[0032] Based on the above technical solution, the present invention can be further improved as follows.

[0033] Furthermore, in step S11, the yttrium salt is yttrium nitrate; the molar ratio of the yttrium salt to the mesoporous silica is 0.1 to 1.0; and the volume of the ethanol is 10 to 30 mL.

[0034] Furthermore, in step S12, the concentration of the sodium hydroxide solution is 1.0–3.0 mol / L; and the temperature of the water bath is 40–60°C.

[0035] The further beneficial effect of adopting the above is that by controlling the appropriate concentration and water bath temperature to regulate the etching rate of mesoporous silicon oxide, it is beneficial to form mesoporous yttrium oxide with a regular structure.

[0036] Furthermore, in step S2, the nickel salt is nickel nitrate; the static aging time is 20-28 hours; and the calcination temperature is 450-600°C.

[0037] The further beneficial effects of adopting the above-mentioned static aging time are: the above-mentioned static aging time is conducive to the good deposition and dispersion of metallic nickel salt on porous yttrium oxide, and the reduced metallic nickel salt is more uniformly dispersed with more reaction sites.

[0038] Too low a calcination temperature is detrimental to the formation of nickel oxide and strong metal-support interactions, while too high a calcination temperature will damage the mesoporous structure. The present invention employs the aforementioned calcination temperature, resulting in a precursor with better technical performance.

[0039] Furthermore, in step S3, the hydrogen concentration of the hydrogen atmosphere is 5-100%, and the total flow rate is 5-50 mL / min.

[0040] All raw materials used in this invention are commercially available.

[0041] A third objective of this invention is to provide the application of the above-mentioned adsorption-enhanced nickel-based catalyst in low-temperature CO2 methanation reactions.

[0042] The beneficial effects of applying this invention are:

[0043] The reaction temperature of the above-mentioned adsorption-enhanced nickel-based catalyst has reached the temperature of CO2-containing tail gas from heavy-emission industries such as thermal power plants and steel plants, and it is expected to directly utilize industrial tail gas for low-temperature CO2 methanation reaction, which has great application prospects.

[0044] Based on the above technical solution, the present invention can be further improved as follows.

[0045] Furthermore, the specific method of the application is as follows:

[0046] The above-mentioned adsorption-enhanced nickel-based catalyst was placed in a fixed-bed reactor, and a mixture of carbon dioxide and hydrogen in a molar ratio of 1:4 was introduced, with a mass hourly space velocity (WHSV) of 6000–30000 mL / g. -1 h -1 The reaction pressure is 0.1–1.0 MPa, and the reaction temperature is 200–420 °C. Attached Figure Description

[0047] Figure 1 To assess the catalytic performance of nickel-based catalysts with different metal loadings and adsorption enhancement.

[0048] Figure 2 To assess the catalytic performance of adsorption-enhanced nickel-based catalysts at different mass space velocities.

[0049] Figure 3 The catalytic performance of an adsorption-enhanced nickel-based catalyst in the CO2 methanation reaction over 125 hours was studied.

[0050] Figure 4To assess the catalytic performance of nickel-based catalysts with different supports.

[0051] Figure 5 The attached diagram shows CO dehydrogenation using nickel-based catalysts with different supports.

[0052] Figure 6 This is a TEM image of mesoporous yttrium oxide.

[0053] Figure 7 This is a TEM image of the adsorption-enhanced nickel-based catalyst prepared in Example 3. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention patent clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this invention. Furthermore, the technical features involved in the various embodiments of this invention patent described below can be combined with each other as long as they do not conflict with each other.

[0055] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following description is merely illustrative and is not intended to limit the invention.

[0056] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover a non-exclusive inclusion. A composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0057] The phrase "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for conventional impurities associated with them. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0058] When a dosage, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4,” “1 to 3,” “1 to 2,” “1 to 2 and 4 to 5,” “1 to 3 and 5,” etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0059] In some instances, approximate terms may correspond to the instrument precision of the measured values. In this specification and claims, scope definitions may be combined and / or interchanged. Unless otherwise stated, these scopes include all subscopes contained therein.

[0060] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the number of elements or components (i.e., the number of times they appear). Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0061] The terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., used in this invention refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms are not necessarily directed at the same embodiment or example. Furthermore, the technical features involved in the various embodiments of the invention can be combined with each other as long as they do not conflict with each other.

[0062] Unless otherwise specified, the raw materials and equipment used in this invention can be purchased from the market or are commonly used in the field. Unless otherwise specified, the methods in the embodiments are conventional methods in the field.

[0063] In some embodiments, the present invention provides an adsorption-enhanced nickel-based catalyst, wherein the adsorption-enhanced nickel-based catalyst uses mesoporous yttrium oxide as a support and a nickel salt as an active component, wherein the mass content of the mesoporous yttrium oxide is 80.0–95.0 wt%, and the mass content of the nickel salt is 5.0–20.0 wt%. Preferably, the mass content of the mesoporous yttrium oxide can be 80.0 wt%, 85.0 wt%, 90.0 wt%, or 95.0 wt%, and correspondingly, the mass content of the nickel salt can be 20.0 wt%, 15.0 wt%, 10.0 wt%, or 5.0 wt%.

[0064] In some embodiments, the mesoporous yttrium oxide has an average pore size of 8.2 nm and a pore volume of 0.54 cm³. 3 / g, specific surface area is 184m² 2 / g; the particle size of the nickel salt is 8.0-9.0nm.

[0065] In some embodiments, the particle size of the adsorption-enhanced nickel-based catalyst is 10-200 mesh. Further, it can be 10 mesh, 20 mesh, 30 mesh, 40 mesh, 50 mesh, 60 mesh, 70 mesh, 80 mesh, 90 mesh, 100 mesh, 110 mesh, 120 mesh, 130 mesh, 140 mesh, 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh, or 200 mesh.

[0066] In one embodiment, a method for preparing an adsorption-enhanced nickel-based catalyst is provided, comprising the following steps:

[0067] S1: Preparation of mesoporous yttrium oxide support

[0068] S11: Weigh yttrium salt, dissolve it in ethanol, and stir thoroughly at room temperature to obtain a first homogeneous solution; add mesoporous silica to the first homogeneous solution, stir at room temperature for 0.5-1 h, then stir in a water bath at 30-40°C to completely evaporate the ethanol, and then calcine in air at 500-600°C for 5-7 h to obtain a white solid;

[0069] S12: The obtained white solid was transferred to sodium hydroxide solution and stirred continuously in a water bath for 12-24 hours. It was then centrifuged and washed with deionized water, and repeated 3-5 times. The precipitate obtained by centrifugation was dried at 100-120℃ for 12-24 hours to obtain mesoporous yttrium oxide support.

[0070] S2: Preparation of precursors

[0071] Weigh out a nickel salt, dissolve it in deionized water, and stir thoroughly at room temperature to obtain a second homogeneous solution; slowly add the mesoporous yttrium oxide support obtained in step S1 to the second homogeneous solution, stir to mix it evenly, allow it to age at room temperature, dry it at 100-120°C for 12-24 hours, and calcine it in air atmosphere for 3-5 hours to obtain the precursor;

[0072] S3: Precursor Restoration

[0073] The precursor obtained from S2 was reduced at atmospheric pressure under a hydrogen atmosphere at 300–600 °C for 4–10 h to obtain an adsorption-enhanced nickel-based catalyst.

[0074] In some embodiments, in step S11 above, the molar ratio of the yttrium salt to the mesoporous silica is 0.1 to 1.0, and may further be 0.1, 0.2, 0.4, 0.6, 0.8 or 1.0; the volume of the ethanol is 10 to 30 mL, and may further be 10 mL, 15 mL, 20 mL, 25 mL or 30 mL.

[0075] In some embodiments, in step S12 above, the concentration of the sodium hydroxide solution is 1.0–3.0 mol / L; and the temperature of the water bath is 40–60°C.

[0076] In some embodiments, in step S2 above, the nickel salt is nickel nitrate; the aging time is 20-28 hours; and the calcination temperature is 450-600°C, or more specifically, 450°C, 500°C, 550°C, or 600°C.

[0077] In some embodiments, in step S3 above, the hydrogen concentration of the hydrogen atmosphere is 5% to 100%, and more specifically, it can be 5%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%; the total flow rate is 5% to 50 mL / min, and more specifically, it can be 5 mL / min, 10 mL / min, or 15 mL / min.

[0078] 20mL / min, 25mL / min, 30mL / min, 35mL / min, 40mL / min, 45mL / min or 50mL / min.

[0079] In some embodiments, the present invention also provides the application of the above-described adsorption-enhanced nickel-based catalyst in a low-temperature CO2 methanation reaction. The specific method of application is as follows: the adsorption-enhanced nickel-based catalyst is placed in a fixed-bed reactor, and a mixed reaction gas of carbon dioxide and hydrogen with a molar ratio of 1:4 is introduced, with a mass hourly space velocity (WHSV) of 6000–30000 mL / g. -1 h -1 The reaction pressure is 0.1–1.0 MPa, and the reaction temperature is 200–420 °C.

[0080] The following description, in conjunction with specific embodiments, provides further details.

[0081] Example 1

[0082] S1: Preparation of mesoporous yttrium oxide support

[0083] S11: Weigh 2.55g of yttrium nitrate hexahydrate, dissolve it in 20mL of ethanol, and stir thoroughly at room temperature for 1h to obtain a first homogeneous solution; add 1.0g of mesoporous silica to the first homogeneous solution, at which point the molar ratio of yttrium nitrate hexahydrate to mesoporous silica is 0.4, and stir at room temperature for 1h; then, under a water bath at 35℃, continue stirring until the ethanol is completely evaporated, and then calcine at 550℃ in air atmosphere for 6h to obtain a white solid product;

[0084] S12: The obtained solid product was transferred to a 2.0 mol / L sodium hydroxide aqueous solution and stirred continuously in a 50°C water bath for 20 h. It was then centrifuged and washed with deionized water, repeated 3 times. After the last wash was performed until the washing solution was neutral, the precipitate obtained by centrifugation was dried at 110°C for 12 h to obtain a mesoporous yttrium oxide support.

[0085] S2: Preparation of precursors

[0086] Weigh 0.25 g of nickel nitrate hexahydrate, dissolve it in 2 mL of deionized water, and stir thoroughly at room temperature to obtain a second homogeneous solution (i.e., an aqueous solution of nickel nitrate hexahydrate); slowly add 1.0 g of the mesoporous yttrium oxide support obtained in step S1 to the second homogeneous solution, stir to mix it evenly, and let it stand and age at room temperature for 24 h to obtain a light green solid, dry it at 110 °C for 12 h, and calcine it at 500 °C in air atmosphere for 4 h to obtain the precursor.

[0087] S3: Precursor Restoration

[0088] The precursor obtained from S2 was reduced at 500℃ under a hydrogen atmosphere and atmospheric pressure for 5 hours to obtain an adsorption-enhanced nickel-based catalyst, named Ni@Y2O3-1.

[0089] The Ni@Y2O3-1 was granulated to a particle size of 40-80 mesh and placed in a fixed-bed reactor for CO2 methanation. A mixture of carbon dioxide and hydrogen in a molar ratio of 1:4 was introduced at a mass hourly space velocity (WHSV) of 15000 mL / g. -1 h -1 The reaction pressure is 0.1 MPa, and the reaction temperature is 200–420 °C.

[0090] Example 2

[0091] Unlike Example 1, in step S2, the amount of nickel nitrate hexahydrate is 0.50 g. Everything else is the same.

[0092] The adsorption-enhanced nickel-based catalyst obtained in this embodiment is named Ni@Y2O3-2.

[0093] Example 3

[0094] Unlike Example 1, in step S2, the amount of nickel nitrate hexahydrate is 0.74 g. Everything else is the same.

[0095] The adsorption-enhanced nickel-based catalyst obtained in this embodiment is named Ni@Y2O3-3.

[0096] Example 4

[0097] Unlike Example 1, in step S2, the amount of nickel nitrate hexahydrate was 1.0 g. All other steps were the same. The adsorption-enhanced nickel-based catalyst obtained in this example is named Ni@Y2O3-4.

[0098] Comparative Example 1

[0099] The support used in this comparative example is mesoporous silica from existing technology, instead of the mesoporous yttrium oxide support prepared in step S1 of Example 3; that is, step S1 of Example 3 is omitted. The specific method is as follows:

[0100] Weigh 0.74 g of nickel nitrate hexahydrate and dissolve it in 8 mL of deionized water. Stir thoroughly at room temperature to obtain an aqueous solution of nickel nitrate hexahydrate. Slowly add 1.0 g of mesoporous silica support to the aqueous solution of nickel nitrate hexahydrate and stir to mix evenly. Let it stand at room temperature for 24 h to age, and obtain a light green solid. Dry it at 110 °C for 12 h and calcine it at 500 °C in air atmosphere for 4 h to obtain the precursor. The reduction and application of the remaining precursors are the same as in Example 3.

[0101] The nickel-based catalyst obtained in this comparative example is named Ni@mesoporous silica.

[0102] Comparative Example 2

[0103] The support used in this comparative example is a commercially available yttrium oxide support from the prior art, instead of the mesoporous yttrium oxide support prepared in step S1 of Example 3; that is, step S1 of Example 3 is omitted. The specific method is as follows:

[0104] Weigh 0.74 g of nickel nitrate hexahydrate and dissolve it in 2 mL of deionized water. Stir thoroughly at room temperature to obtain an aqueous solution of nickel nitrate hexahydrate. Slowly add 1.0 g of commercial yttrium oxide support to the aqueous solution of nickel nitrate hexahydrate and stir to mix evenly. Allow to stand and age at room temperature for 24 h to obtain a light green solid. Dry at 110 °C for 12 h and calcine at 500 °C in air atmosphere for 4 h to obtain the precursor. The reduction and application of the remaining precursors are the same as in Example 3.

[0105] The nickel-based catalyst obtained in this comparative example is named Ni / Y2O3.

[0106] The CO2 conversion and CH4 selectivity of the catalysts prepared in Examples 1-4 and Comparative Examples 1-2 for low-temperature CO2 methanation reactions are shown in Table 1.

[0107] Table 1. CO2 conversion and CH4 selectivity of each catalyst for low-temperature CO2 methanation reaction.

[0108]

[0109] Table 1 shows the CO2 conversion and CH4 selectivity of each catalyst in the low-temperature CO2 methanation reaction. Comparing the examples and comparative examples, it was found that the Ni@Y2O3-3 catalyst in Example 3 had the best low-temperature CO2 methanation activity, achieving a CO2 conversion of 65% and a methane selectivity of 99.8% at 240°C.

[0110] Experimental Results 2

[0111] The adsorption-enhanced nickel-based catalyst (Ni@Y2O3-3) prepared in Example 3 is compared with the low-temperature CO2 methanation performance of similar catalysts reported in the prior art, as shown in Table 2.

[0112] Table 2 Comparison of low-temperature CO2 methanation performance between adsorption-enhanced nickel-based catalysts and similar reported catalysts.

[0113]

[0114] As shown in Table 2, the adsorption-enhanced nickel-based catalyst (Ni@Y2O3-3) prepared in Example 3 can achieve a CO2 conversion rate of 65% at a low temperature of 240℃, while other similar catalysts generally only achieve a CO2 conversion rate of about 30% at similar reaction temperatures, and the temperature required to achieve a similar CO2 conversion rate exceeds 300℃. This demonstrates the excellent low-temperature CO2 methanation activity of the adsorption-enhanced nickel-based catalyst.

[0115] Experimental Results 3

[0116] The CO2 adsorption performance of the catalysts in Example 3 and the comparative example is shown in Table 3.

[0117] Table 3 CO2 adsorption performance of the adsorption-enhanced nickel-based catalyst and the comparative catalyst.

[0118]

[0119] As shown in Table 3, the adsorption-enhanced nickel-based catalyst Ni@Y2O3-3 prepared in Example 3 has a CO2 adsorption capacity as high as 1519 μmol·g. -1 The yield is significantly higher than that of Ni@mesoporous silica prepared in Comparative Example 1 (797.5 μmol·g). -1 Ni / Y₂O₃ (910.1 μmol·g) prepared in Comparative Example 2 and in Comparative Example 2 -1The CO2 adsorption capacity of the adsorption-enhanced nickel-based catalyst Ni@Y2O3-3 prepared in Example 3 was also observed, particularly for weak and moderately strong CO2 adsorption within the reaction temperature range. -1 The two samples are Ni@mesoporous silica (491.9 μmol·g) prepared in Comparative Example 1. -1 The Ni / Y2O3 (464.0 μmol·g) prepared in Comparative Example 2 and Comparative Example 2 -1 The adsorption capacity of the nickel-based catalyst Ni@Y2O3-3 prepared in Example 3 is 2.6 times and 2.8 times that of yttrium oxide. This indicates that the adsorption-enhanced nickel-based catalyst Ni@Y2O3-3 prepared in Example 3 has extremely strong CO2 adsorption capacity, which is mainly due to the strong alkalinity of yttrium oxide itself and the large specific surface area and abundant pore structure of the catalyst.

[0120] Experimental Results 4

[0121] The parameter characterization data of the catalysts in each embodiment are shown in Table 4. The mesoporous yttrium oxide is the mesoporous yttrium oxide support obtained in step S12 of Example 1. The specific surface area and various parameters of Examples 1-4 and Comparative Examples 1-2 are parameter data of the catalysts after loading with active nickel.

[0122] Table 4. Catalyst parameter characterization data for examples and comparative examples.

[0123]

[0124] As shown in Table 4, the pore volume and average pore size decreased after loading active nickel metal onto mesoporous yttrium oxide in Examples 1-4, indicating that some active metal was filled or loaded in the mesopores, and the particle size of the active nickel salt was controlled at 8-8.5 nm. Compared with the data of Comparative Example 2, it was found that using mesoporous yttrium oxide as a support can effectively control the particle size of the active nickel salt, thereby improving the catalytic activity of the catalyst.

[0125] Figure 1 The results of the adsorption-enhanced nickel-based catalysts with different metal loadings in Examples 1-4 are compared in the range of 200-420℃. It can be seen that the Ni@Y2O3 catalyst can catalyze the CO2 methanation reaction at 200℃. As the metal loading increases, the low-temperature activity of the catalyst gradually increases, and the activity reaches its highest when the nickel content reaches more than 15%.

[0126] Figure 2 The optimal catalyst in Example 3 was given at 240°C and 15,000–30,000 mL g. -1 h -1 The low-temperature CO2 methanation performance within the space velocity range shows that the Ni@Y2O3 catalyst can still maintain a high CO2 conversion rate and nearly 100% CH4 selectivity at high space velocities.

[0127] Figure 3 The optimal catalyst in Example 3 is given at 300°C, 0.1 MPa, and 15000 mL g. -1 h -1 The long-term operational stability under reaction conditions shows that even at a high temperature of 300℃, the catalyst performance remains stable, with a CO2 conversion rate of 80% and a CH4 selectivity of 100%.

[0128] Figure 4 The catalytic performance of the catalysts in Example 3 and Comparative Examples 1-2 is presented. It can be seen that regardless of whether mesoporous silica or commercial Y2O3 is used as the support, the overall CO2 methanation performance of the catalysts, especially the low-temperature performance, is far inferior to that of the catalyst in Example 3. At 240°C, the CO2 conversion rates of the catalysts in Comparative Examples 1 and 2 are only 2.2% and 1.8%, respectively. To achieve a CO2 conversion rate of over 60%, the catalysts in Comparative Examples 1 and 2 require high temperatures of 280°C and 340°C, respectively, which demonstrates the superiority of the catalyst in Example 3 in the low-temperature CO2 methanation reaction.

[0129] Figure 5 The CO desorption results of the catalysts in Example 3 and Comparative Example 1 are presented. It can be seen that after purging the catalyst in Example 3 for 3 hours, the relative intensity of CO species adsorbed on the surface hardly changed, while the relative intensity of CO species adsorbed on the surface of the catalyst in Comparative Example 1 decreased by more than 60% after purging for 3 hours. This indicates that the catalyst in Example 3 also has extremely strong CO adsorption capacity.

[0130] Figure 6 The image shows a TEM image of the mesoporous yttrium oxide support. As can be seen from the image, the mesoporous yttrium oxide support obtained by the method of the present invention has an ordered mesoporous structure with a regular structure.

[0131] Figure 7 The image shows a TEM image of the adsorption-enhanced nickel-based catalyst prepared in Example 3. As can be seen from the image, the mesoporous yttrium oxide loaded with active metal maintains its original structural morphology, and the particle size distribution of the active nickel metal is very concentrated, indicating that the particle size is uniform. The mesoporous yttrium oxide effectively controls the particle size of the active metal nickel salt.

[0132] In summary, the adsorption-enhanced nickel-based catalyst of the present invention has both extremely strong adsorption capacity for the reactant CO2 and the intermediate CO, which is beneficial for the conversion of CO2 to CH4 via CO, and therefore has excellent low-temperature CO2 methanation activity.

[0133] References:

[0134] 1.Y.Li,Y.Men,S.Liu,J.Wang,K.Wang,Y.Tang,W.An,X.Pan,L.Li,Remarkablyefficient and stable Ni / Y2O3 catalysts for CO2 methanation:Effect of citricacid addition,Appl.Catal.B-Environ.293(2021)120206.

[0135] 2.Q.Liu,S.Wang,S.Lv,F.Han,J.Ouyang,High Stability of the Ni-YCe / Diatomite catalyst for CO2 methanation:The synergistic coupling of citricacid and Y2O3,ACS Sustainable Chem.Eng.11(2023)12946-12958.

[0136] 3.C.Italiano,J.Llorca,L.Pino,M.Ferraro,V.Antonucci,A.Vita,CO and CO2methanation over Ni catalysts supported on CeO2,Al2O3 and Y2O3 oxides,Appl.Catal.B-Environ.264(2020)118494.

[0137] 4.Y.Yan,Y.Dai,Y.Yang,A.A.Lapkin,Improved stability of Y2O3 supportedNi catalysts for CO2 methanation by precursor-determined metal-supportinteraction,Appl.Catal.B-Environ.,237(2018)504-512.

[0138] 5.RAEl-Salamony,SAEl-Sharaky,SAAl-Temtamy,AMAl-Sabagh,HMKilla,CO2 valorization into synthetic natural gas (SNG) using a Co–Nibimetallic Y2O3 based catalysts.Int.J.Chem.React.Eng.19(2021)571-583.

[0139] 6.X.Fang, L.Xia, S.Li, Z.Hong, M.Yang,

[0140] The embodiments herein cover any points not exhaustively within the scope of the technical claims of this invention, as well as new technical solutions formed by equivalent substitutions of one or more technical features in the embodiments. These are all within the scope of the claims of this invention. Unless otherwise specified, there is no irreplaceable unique combination among all parameters involved in the solutions of this invention.

[0141] It will be readily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An adsorption-enhanced nickel-based catalyst, characterized in that, The adsorption-enhanced nickel-based catalyst uses mesoporous yttrium oxide as a support and nickel salt as the active ingredient, wherein the mass content of the mesoporous yttrium oxide is 80.0–95.0 wt% and the mass content of the nickel salt is 5.0–20.0 wt%.

2. The adsorption-enhanced nickel-based catalyst according to claim 1, characterized in that, The mesoporous yttrium oxide has an average pore size of 8.2 nm and a pore volume of 0.54 cm³. 3 / g, specific surface area is 184m² 2 / g; the particle size of the nickel salt is 8.0-9.0nm.

3. The adsorption-enhanced nickel-based catalyst according to claim 1, characterized in that, The particle size of the adsorption-enhanced nickel-based catalyst is 10-200 mesh.

4. A method for preparing the adsorption-enhanced nickel-based catalyst according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Preparation of mesoporous yttrium oxide support S11: Weigh yttrium salt, dissolve it in ethanol, and stir thoroughly at room temperature to obtain a first homogeneous solution; add mesoporous silica to the first homogeneous solution, stir at room temperature for 0.5-1 h, then stir in a water bath at 30-40°C to completely evaporate the ethanol, and then calcine in air at 500-600°C for 5-7 h to obtain a white solid; S12: The obtained white solid was transferred to sodium hydroxide solution and stirred continuously in a water bath for 12-24 hours. It was then centrifuged and washed with deionized water, and repeated 3-5 times. The precipitate obtained by centrifugation was dried at 100-120℃ for 12-24 hours to obtain mesoporous yttrium oxide support. S2: Preparation of precursors Weigh out a nickel salt, dissolve it in deionized water, and stir thoroughly at room temperature to obtain a second homogeneous solution; slowly add the mesoporous yttrium oxide support obtained in step S1 to the second homogeneous solution, stir to mix it evenly, allow it to age at room temperature, dry it at 100-120°C for 12-24 hours, and calcine it in air atmosphere for 3-5 hours to obtain the precursor; S3: Precursor Restoration The precursor obtained from S2 was reduced at atmospheric pressure under a hydrogen atmosphere at 300–600 °C for 4–10 h to obtain an adsorption-enhanced nickel-based catalyst.

5. The method for preparing the adsorption-enhanced nickel-based catalyst according to claim 4, characterized in that, In step S11, the yttrium salt is yttrium nitrate; the molar ratio of the yttrium salt to the mesoporous silica is 0.1 to 1.0; and the volume of the ethanol is 10 to 30 mL.

6. The method for preparing the adsorption-enhanced nickel-based catalyst according to claim 4 or 5, characterized in that, In step S12, the concentration of the sodium hydroxide solution is 1.0–3.0 mol / L; the temperature of the water bath is 40–60 °C.

7. The method for preparing the adsorption-enhanced nickel-based catalyst according to claim 4 or 5, characterized in that, In step S2, the nickel salt is nickel nitrate; the aging time is 20-28 hours; and the calcination temperature is 450-600°C.

8. The method for preparing the adsorption-enhanced nickel-based catalyst according to claim 4 or 5, characterized in that, In step S3, the hydrogen concentration of the hydrogen atmosphere is 5-100%, and the total flow rate is 5-50 mL / min.

9. The application of the adsorption-enhanced nickel-based catalyst according to any one of claims 1-3 or the adsorption-enhanced nickel-based catalyst prepared by any one of claims 4-8 in the low-temperature CO2 methanation reaction.

10. The application according to claim 9, characterized in that, The specific method of application is as follows: The adsorption-enhanced nickel-based catalyst according to any one of claims 1-3 or the adsorption-enhanced nickel-based catalyst prepared by any one of claims 4-8 is placed in a fixed-bed reactor, and a mixed reaction gas of carbon dioxide and hydrogen with a molar ratio of 1:4 is introduced, with a mass hourly space velocity of 6000–30000 mL / g. -1 h -1 The reaction pressure is 0.1–1.0 MPa, and the reaction temperature is 200–420 °C.

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