High-strength, fine-particle diameter methanation catalyst and method for preparing same

Abstract

The application provides a high-strength micro-particle diameter methanation catalyst and a preparation method, which comprises the following steps: S1: dispersing a catalyst carrier, an acid colloidal solvent and a nitrate mixture in water to obtain a colloidal mixed solution; S2: performing aging treatment on the colloidal mixed solution to obtain a precursor colloid; S3: performing kneading extrusion and autoclaved forming maintenance on the precursor colloid to obtain precursor particles; S4: performing first calcination treatment on the precursor particles to obtain a metal oxide carrier; S5: performing impregnation treatment on the metal oxide carrier in an active ion solution to obtain a catalyst precursor; and S6: performing second calcination treatment on the catalyst precursor to obtain the high-strength micro-particle diameter methanation catalyst. The catalyst obtained by the method is particularly suitable for a reactor design that needs frequent start-stop, and the catalyst has high strength and catalytic activity and has good catalytic stability in an environment that needs frequent start-stop.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of methanation catalysts, in particular to a high-strength microparticle methanation catalyst and a preparation scheme thereof. BACKGROUND

[0002] Methanation refers to the process of generating CH4 from CO / CO2 and H2 under certain temperature, pressure and catalyst. In recent years, with the rapid development of coal-based substitute natural gas industry in China, methanation, as one of the core technologies, has attracted more and more attention. As the key of methanation technology, the performance of methanation catalyst directly determines the production efficiency and quality of methane. At present, the most widely used methanation catalyst in the market is Ni-based catalyst, which generally uses Ni as the active component, alumina as the carrier, and different additives are added to obtain the methanation catalyst by impregnation or coprecipitation.

[0003] At present, the deactivation of methanation catalyst is mainly caused by the following reasons: first, the methanation reaction is a strong exothermic reaction, and high-concentration methanation reaction will generate reaction heat, which will rapidly increase the temperature of the catalyst bed, cause the agglomeration of active metal nickel, reduce the active sites, and cause the sintering and deactivation of the catalyst; second, the methanation catalyst will be shut down in various situations during use, and a large amount of inert gas will pass through the catalyst bed during the start-up and shutdown process, which will easily cause the pulverization and deactivation of the methanation catalyst.

[0004] In order to overcome the above problems and improve the catalytic activity and stability of the methanation catalyst, researchers have tried to replace the catalyst carrier and adjust the molding process in recent years to optimize the structure and strength of the catalyst and reduce the risk of catalyst deactivation.

[0005] For example, patent CN114425320B discloses a preparation method of a methanation catalyst, which comprises the following steps: mixing pseudoboehmite and a crystalline compound of a rare earth metal complex, then adding one or more of a peptizing agent, a pore-forming agent and a extrusion aid, and then performing kneading molding, drying and calcination. The patent discloses a catalyst carrier with suitable structure and surface properties, which significantly improves the catalyst activity and sintering resistance.

[0006] However, the problem of the above-mentioned patent is that the strength of the methanation catalyst green body prepared by kneading molding is low, and the final strength is also low, which is easy to deform during transportation and drying, and is still easy to pulverize and deactivate during start-up and shutdown. The performance of the final product is difficult to meet the production requirements.

[0007] Therefore, it is necessary to provide a methanation catalyst with high strength and high catalytic stability. SUMMARY

[0008] The application provides a high-strength micro-particle diameter methanation catalyst and a preparation method thereof.

[0009] In a first aspect, the application provides a high-strength micro-particle diameter methanation catalyst, comprising the following steps:

[0010] S1: dispersing a catalyst carrier, an acid peptizing agent and a nitrate mixture in water to obtain a colloidal mixed solution; wherein the catalyst carrier comprises pseudo-boehmite, the nitrate mixture comprises at least two of potassium nitrate, sodium nitrate and lithium nitrate, and the mass proportion of each component in the nitrate mixture is not less than 30%;

[0011] S2: performing aging treatment on the colloidal mixed solution to cross-link aluminum hydroxyl in the pseudo-boehmite under the action of the acid peptizing agent and the nitrate mixture to form a network structure, thereby obtaining a precursor colloid;

[0012] S3: performing kneading extrusion, steam pressure molding and curing on the precursor colloid to cause the precursor to dissolve and recrystallize under the action of the nitrate mixture and steam pressure, thereby forming a crystal network structure, thereby obtaining a precursor particle;

[0013] S4: performing first calcination treatment on the precursor particle to cause the precursor to dehydrate and oxidize, thereby obtaining a metal oxide carrier;

[0014] S5: immersing the metal oxide carrier in an active ion solution to cause the metal oxide carrier to load active ions, thereby obtaining a catalyst precursor; the active ion solution comprises a nickel salt;

[0015] S6: performing second calcination treatment on the catalyst precursor to cause the active ions on the metal oxide carrier to activate and form active sites, thereby obtaining a high-strength micro-particle diameter methanation catalyst.

[0016] According to the present application, the high-strength microparticle-size methanation catalyst uses pseudo-boehmite as the main material of the catalyst carrier, is treated by adding an acidic peptizing agent, and is introduced into a nitrate mixture for synergistic aging, so that the precursor colloid forms a multiple cross-linking network structure, which can improve the cohesion of the colloid and the stability of the molding, and provide a stable skeleton support for the subsequent autoclaving crystallization process; after kneading and extrusion molding, the precursor is subjected to autoclaving treatment to promote the dissolution-recrystallization of the internal crystals of the precursor, and the nitrate mixture can provide a dissolution-recrystallization environment to promote the recrystallization process. The multiple synergistic effects of the acidic peptizing agent, the nitrate mixture, and the autoclaving process can promote the in-situ formation of a monolithic continuous crystal ceramic structure with a pore structure in the aging skeleton, so that the mechanical strength (compression resistance and wear resistance) and thermal stability of the catalyst are significantly higher than those of a traditional extruded catalyst, which can reduce wear and powdering during use and prolong the service life of the catalyst.

[0017] Specifically, in step S1, the catalyst carrier, the acidic peptizing agent, and the nitrate mixture are uniformly dispersed in water. The acidic peptizing agent ionizes in water to generate H + , which can make the surface of the carrier particles positively charged. The charged particles can inhibit the agglomeration and sedimentation of the particles caused by van der Waals force through electrostatic repulsion. This stable and uniform sol system can provide a good initial dispersion state and reaction interface for subsequent aging and nitrate mixture synergistic autoclaving molding.

[0018] In step S2, the colloid mixed solution is subjected to aging treatment. During the aging process, the acidic peptizing agent activates the aluminum hydroxyl group on the surface of the pseudo-boehmite, which can form stable complexation or hydrogen bonding with the nitrate ions in the solution, facilitating further cross-linking. The multiple cations provided by the nitrate mixture can form electrostatic adsorption or complexation with the carrier surface-Al-OH with different strengths, so that the colloid can form a multi-level network with strong and weak bonds during the aging process, enhancing the internal strength and toughness of the colloid. At the same time, the mixed system of the nitrate mixture can reduce the solubility of the local solution, slow down the sedimentation speed of the colloid, and promote the formation of a uniform three-dimensional network structure. The three-dimensional network structure formed by the synergistic action of the two can improve the cohesion of the colloid, reduce shrinkage and cracking during subsequent molding, and thus provide a stable structural basis for subsequent molding and calcination.

[0019] In step S3, the precursor colloid is subjected to kneading, extrusion, autoclaving, and curing. Kneading can further homogenize the precursor colloid, and extrusion molding can give the kneaded colloid a specific size structure.

[0020] Under the hydrothermal conditions, the nitrate mixture system can provide a high concentration of ion environment, promote the uniform progress of local dissolution-recrystallization process, and at the same time, different cations can be beneficial to form crystals with uniform size through steric hindrance and doping in the lattice rearrangement process during the hydrothermal process, so as to maintain the pore structure, and through the synergy of multiple cations, the precursor gel can be converted into a stable γ-Al2O3 crystal network. Thus, in the hydrothermal molding process, the nitrate mixture can optimize the crystal structure in the gel through synergy, and improve the load activity and mechanical strength of the catalyst carrier.

[0021] In step S4, the precursor particles are subjected to a first calcination treatment to remove physically adsorbed water and bound water in the structure, and a metal oxide carrier with high specific surface area can be formed. This process helps to expose more pores and sites, providing stable support for subsequent loading of active components.

[0022] In step S5, the metal oxide carrier is immersed in an active ion solution to obtain a catalyst precursor, and active metals are loaded in the form of ions on the surface and in the pores of the catalyst carrier.

[0023] In step S6, the catalyst precursor is subjected to a second calcination treatment to reduce the active ions on the catalyst carrier to metal state active sites, forming a high-density active site with stable structure and uniform distribution. Through the second calcination treatment, not only the binding firmness of the active metal is improved, but also the sintering resistance and mechanical strength of the catalyst are enhanced.

[0024] Therefore, the methanation catalyst prepared by the above method has high mechanical strength, high CO2 conversion rate and excellent cycle stability, and is particularly suitable for long-term operation under frequent start-stop or high heat load conditions, which can effectively reduce the risk of pulverization and inactivation and improve the safety and economy of industrial methanation devices.

[0025] In some embodiments, the nitrate mixture in step S1 includes NaNO3 and KNO3. As an example, the mass ratio of NaNO3 and KNO3 in an embodiment of the present application is 60:40.

[0026] In some embodiments, the catalyst carrier further includes α-Al2O3, and the mass ratio of the pseudoboehmite and α-Al2O3 is (3-10):1.

[0027] In the above-mentioned embodiments, by using the pseudo-boehmite and the α-Al2O3 in the above-mentioned mass ratio, the thermal stability and the mechanical strength of the catalyst carrier can be improved by introducing the α-Al2O3, and the risk of shrinkage and structure collapse of the carrier during high-temperature calcination can be reduced; meanwhile, the presence of the α-Al2O3 can optimize the pore structure distribution of the carrier, and more stable sites can be provided for the dispersion of active metal ions, thereby improving the sintering resistance and service life of the catalyst.

[0028] In some embodiments, the average particle size of the pseudo-boehmite is 50-150 nm, and the average particle size of the α-Al2O3 is 1-5 μm. For example, in an embodiment of the present application, the pseudo-boehmite with an average particle size of 100 nm is used, and the α-Al2O3 with an average particle size of 2 μm is used.

[0029] In some embodiments, the acidic peptizing agent comprises an aluminum salt, an organic carboxylic acid polymer and a nitrogen-containing heterocyclic carboxylic acid, and the mass ratio of the aluminum salt, the organic carboxylic acid polymer and the nitrogen-containing heterocyclic carboxylic acid is 1:0.1-0.5:0.01-0.05.

[0030] In the above-mentioned embodiments, when the above-mentioned acidic peptizing agent is used, the aluminum salt ionizes Al 3+ and H + , which can form a coordination structure with the hydroxyl groups on the surface of the carrier, enhance the local stability and skeleton support of the precursor colloid, and at the same time, can maintain a suitable acidic environment, reduce excessive agglomeration of the colloidal particles, and promote mutual crosslinking and crystal nucleus formation between the particles. The multiple carboxyl groups (-COOH) on the molecular skeleton of the organic carboxylic acid polymer form hydrogen bonds or coordination bonds with the aluminum hydroxyl groups on the carrier, and promote the formation of an organic flexible network. Further, the nitrogen-containing heterocyclic carboxylic acid has dual coordination ability of carboxyl groups and nitrogen heterocyclic rings, and can form N, O dual coordination structures with metal ions, and can form hydrogen bonds or bridge combination through metal ions with the carboxyl groups of the organic carboxylic acid polymer, further strengthening the flexible network. The synergistic effect of the three can promote the formation of a dense and uniform three-dimensional crosslinked network, improve the cohesion and forming stability of the precursor colloid, and thereby improve the mechanical strength and thermal stability of the catalyst.

[0031] In some embodiments, the organic carboxylic acid polymer comprises at least one of polyacrylic acid, polymethacrylic acid and acrylic acid-maleic anhydride copolymer, and the weight average molecular weight of the organic carboxylic acid polymer is 80000-150000 Da. For example, in an embodiment of the present application, polyacrylic acid with a weight average molecular weight of 100000 Da is used.

[0032] In some embodiments, the aluminum salt comprises at least one of aluminum nitrate, aluminum chloride and aluminum sulfate. For example, in an embodiment of the present application, the aluminum salt used is aluminum nitrate.

[0033] In some embodiments, the nitrogen-containing heterocyclic carboxylic acid comprises at least one of picolinic acid, nicotinic acid, and isonicotinic acid. As an example, the nitrogen-containing heterocyclic carboxylic acid used in an embodiment of the present application is picolinic acid.

[0034] In some embodiments, in the step S1, 80-100 parts by mass of the catalyst carrier, 5-15 parts by mass of the acidic peptizing agent, and 0.5-3 parts by mass of the nitrate mixture are dispersed in 80-100 parts by mass of water to obtain a colloidal mixed solution.

[0035] In some embodiments described above, the colloidal mixed solution prepared according to the mass ratio described above, the nitrate mixture provides mixed cation effects, which can coordinate or bridge with the aluminum salt, the organic carboxylic acid polymer, and the nitrogen-containing heterocyclic carboxylic acid in the acidic peptizing agent, thereby promoting the preliminary formation of the multi-level cross-linked network. This synergistic effect can promote the formation of a dense and stable precursor during the subsequent aging and autoclaving of the colloidal mixed solution, laying a foundation for a catalyst carrier with high strength and high thermal stability.

[0036] In some embodiments, in the step S2, the aging treatment is performed at 300-800 W of microwave heating to 60-90°C for 2-4 h.

[0037] In some embodiments described above, the microwave action can accelerate the rearrangement of the pseudo-boehmite crystal phase structure and the migration of water molecules in the colloidal system, promote the stable combination and uniform dispersion of active ions, thereby shortening the aging time and improving the density and stability of the carrier structure.

[0038] In some embodiments, the kneading and extrusion are performed to obtain a cylindrical rubber strip with a diameter of 1-3 mm. Based on the embodiments described above, the internal density and the uniformity of the pore structure of the strip-shaped material can be increased, and the smaller size of the catalyst can reduce the temperature difference between the inside and outside of the catalyst during the temperature rising and falling processes, thereby reducing the risk of pulverization. As an example, the kneading and extrusion in an embodiment of the present application are performed to obtain a cylindrical rubber strip with an average diameter of 2 mm.

[0039] In some embodiments, the autoclaving and curing are performed under a water vapor atmosphere at 0.8-1.5 MPa and 180-200°C for 12-24 h, and then the product is cured at 20-40°C for 40-48 h.

[0040] In some embodiments described above, the autoclaving is performed under a water vapor atmosphere at a steam pressure of 0.8-1.5 MPa and a temperature of 180-200°C for 12-24 h. Under this condition, the dissolved Al 3+ The nitrate mixture can provide a high ion concentration environment under the autoclaving condition, and the NO3 -The transient coordination complex can be formed with the carrier surface-Al-OH, and the Al 3+ The activation energy can accelerate the recrystallization process; the organic carboxylic acid polymer promotes the formation of a flexible carboxyl network in the above environment, which can limit the abnormal growth of the crystal grains and enhance the stability of the colloid; the nitrogen-containing heterocyclic carboxylic acid can coordinate with metal cations in the presence of water vapor, thereby regulating the local metal ion concentration and promoting uniform deposition; the organic carboxylic acid polymer provides a stable flexible network, while the nitrogen-containing heterocyclic carboxylic acid can bridge the organic network and the inorganic crystal, and the two synergistically promote the uniform distribution of the crystal and the stable crystal network of γ-Al2O3; then, the product after the steaming is cured at 20-40°C for 40-48h to further stabilize the crystal structure and release internal stress. The process helps to improve the mechanical strength and catalytic activity stability of the catalyst.

[0041] In some embodiments, the conditions of the impregnation treatment include: first segment impregnation treatment, pre-calcination treatment, and second segment impregnation treatment;

[0042] The conditions of the first segment impregnation treatment include: impregnation in the first impregnation solution at 60-80°C for 2-4h; the first impregnation solution includes Ni 2+ , Y 3+ , and Zr 4+ , wherein the concentration of Ni 2+ is 1.2-1.8mol / L, the concentration of Y 3+ is 0.05-0.1mol / L, and the concentration of Zr 4+ is 0.02-0.05mol / L.

[0043] The conditions of the pre-calcination treatment include: calcination in an oxygen atmosphere at 300-350°C for 0.5-1h.

[0044] The conditions of the second segment impregnation treatment include: impregnation in the second impregnation solution at 20-40°C for 12h; the second impregnation solution includes Ni 2+ , rare earth metal ions, Mo 6+ , and Pt 4+ , wherein the concentration of Ni 2+ is 0.5-1.0mol / L, the concentration of the rare earth metal ions is 0.2-0.4mol / L, the rare earth metal ions include Ce 3+ , the concentration of Mo 6+ is 0.01-0.03mol / L, and the concentration of Pt 4+ is 0.001-0.005mol / L.

[0045] In the above embodiments, the catalyst structure with high stability core and functionalized high activity shell is formed by stepwise impregnation. It can be understood that, in the first impregnation, Y 3+ In the subsequent pre-calcination process, Y 3+ can partially enter the Al2O3 lattice to form doping, further slowing down the growth of Al2O3 grains, thereby reducing sintering; low concentration of Zr 4+ In the calcination process, ZrO2 microcrystals are generated on the surface of the carrier, which can act as physical barriers when Ni particles migrate at high temperatures; in the second impregnation, Ce 3+ is introduced, which forms CeO2 after calcination, which can adjust the redox environment on the surface of the carrier, provide oxygen vacancies, and promote the dispersion of Ni particles; Mo 6+ can form a small amount of Mo-O-Ni interface to adjust the electronic state of Ni and improve the adsorption and activation ability of the catalyst for CO2; Pt 4+ In the reduction stage, through active H2, the reduction activation energy barrier of NiO is reduced, thereby promoting the reduction of NiO to metal Ni, promoting the refinement of Ni particles, and making the active sites more uniformly distributed. The synergistic effect of the stable core formed by the first impregnation calcination and the high activity shell functionalized in the second impregnation not only improves the high temperature stability of the core of the catalyst, but also improves the dispersion of the active sites, thereby improving the catalytic activity and stability of the catalyst.

[0046] In some embodiments, the conditions of the first calcination treatment include: calcination treatment at 350-450°C for 2-4h in an oxygen-containing atmosphere.

[0047] In the above embodiments, calcination under the above conditions can be understood as follows: the first calcination treatment can remove organic residues, promote the decomposition of inorganic salts in the precursor, and initially form a stable oxide structure to provide a good carrier surface for subsequent impregnation and activation treatment.

[0048] In some embodiments, in step S6, the conditions of the second calcination treatment include: calcination treatment at 350-450°C for 0.5-1h in a hydrogen-containing and nitrogen-containing atmosphere, and then heating to 500-550°C for constant temperature calcination for 2-3h.

[0049] In the above embodiments, the second calcination treatment is first calcined at 350-450°C for 0.5-1h to realize the reduction and activation of part of the active metal; then heated to 500-550°C and constant temperature calcination for 2-3h to promote the combination of active metal species and the carrier, form high dispersion of active sites, and improve the thermal stability and mechanical strength of the catalyst. Through the above segmented atmosphere calcination, the uniformity of metal particle size can be improved, sintering can be reduced, and the low temperature activity and long life performance of the catalyst in the methanation reaction can be improved.

[0050] In a second aspect, the application provides a high-strength micro-particle-size methanation catalyst prepared by the method according to any one of the first aspect.

[0051] According to the application, the catalyst prepared by the method according to any one of the first aspect has high mechanical strength, high catalytic activity and high catalytic stability.

[0052] In a third aspect, the application provides a use of the catalyst according to any one of the second aspect for preparing methane from a carbon source and a hydrogen source.

[0053] According to the application, the catalyst provided by the second aspect has good catalytic activity and catalytic stability for preparing methane from a carbon source and a hydrogen source.

[0054] In a fourth aspect, the application provides a method for preparing methane, which comprises catalyzing a carbon source and a hydrogen source by the catalyst according to any one of the second aspect to obtain methane.

[0055] According to the application, the catalyst provided by the second aspect has good catalytic activity and catalytic stability.

[0056] Compared with the prior art, the application has at least the following beneficial effects:

[0057] The methanation catalyst prepared by the method provided by the application has a pseudo-boehmite carrier, and the mechanical strength of the catalyst is improved by adding an acid peptizing agent and a nitrate mixture for aging and steam pressure molding. At the same time, the step-by-step impregnation is used to control the formation of a certain core-shell distribution structure of the catalyst, so as to reduce the risk of catalyst pulverization caused by too fast temperature rise and internal and external temperature difference. The method ensures the catalytic activity of the catalyst while giving the catalyst certain high-temperature resistance. The catalyst provided by the application has high mechanical strength, high catalytic activity and thermal stability, and can maintain stable operation under long-period, high-temperature and high-air-speed methanation reaction conditions. BRIEF DESCRIPTION OF DRAWINGS

[0058] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the application and, together with the description, serve to explain the principles of the application.

[0059] Figure 1 The actual appearance of the methanation catalyst obtained in an embodiment of the application is shown in the figure. DETAILED DESCRIPTION

[0060] The embodiments or implementation schemes in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments.

[0061] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples with appropriate solutions.

[0062] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood to indicate or imply relative importance or implicitly indicate the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0063] In the description of the present specification, "parts" means "mass parts" unless otherwise specified.

[0064] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only for the purpose of explaining the present application and cannot be understood as a limitation of the present application. The specific technology or conditions not noted in the embodiments are performed according to the technology or conditions described in the literature in the art or according to the product manual. The reagents or instruments not noted by the manufacturer are all conventional products that can be obtained by purchase in the market.

[0065] Pseudo-boehmite type PB-ZK, Al2O3 content ≥ 75%, average particle size 100 nm;

[0066] α-Al2O3 type D3-A08, Al2O3 purity ≥ 99.99%, average particle size 2 μm;

[0067] Polyacrylic acid, weight average molecular weight 100000 Da;

[0068] Picolinic acid is 2-picolinic acid, CAS number: 98-98-6.

[0069] Preparation of NaNO3-KNO3 nitrate mixture:

[0070] 60 parts by mass of NaNO3 and 40 parts by mass of KNO3 were weighed, stirred at 100 rpm for 30 min, and a NaNO3-KNO3 nitrate mixture was obtained.

[0071] Example 1

[0072] Preparation of high-strength micro-particle diameter methanation catalyst

[0073] S1: 90 parts by mass of pseudo-boehmite, 10 parts by mass of α-Al2O3 were dispersed in 100 parts by mass of water, and then 5 parts by mass of aluminum nitrate, 1 part by mass of polyacrylic acid, 0.1 part by mass of 2-picolinic acid, and 1 part by mass of a NaNO3-KNO3 nitrate mixture were added to obtain a colloidal mixed solution;

[0074] S2: The above colloidal mixed solution was subjected to high-speed shearing stirring at 1500 rpm for 1 h to form a uniform colloid, and then was heated to 80℃ by microwave with a power of 500 W, and was aged for 3 h to obtain a precursor colloid;

[0075] S3: The precursor colloid was kneaded and then was extruded into a strip forming device, and the extruded particle diameter was controlled to be 2 mm; the formed particles were placed in a steam autoclave and were treated at 200℃ and 1 MPa for 12 h, and then were naturally cooled to 20℃ and were cured for 48 h;

[0076] S4: The cured colloid was calcined at 400℃ in an oxygen atmosphere for 3 h to obtain a metal oxide carrier;

[0077] S5: The above metal oxide carrier was first soaked in a mixed solution of nickel nitrate, yttrium nitrate and zirconium nitrate at 60℃ for 3 h, and the solid-liquid ratio was 1 g:5 mL; the molar concentration of nickel element in the mixed solution of nickel nitrate, yttrium nitrate and zirconium nitrate was 1.5 mol / L, the molar concentration of yttrium element was 0.08 mol / L, and the molar concentration of zirconium element was 0.03 mol / L; after the soaking was completed, the carrier was calcined at 300℃ in an oxygen atmosphere for 1 h, and then was soaked in a mixed solution of nickel nitrate, cerium nitrate, ammonium heptamolybdate and tetraammine platinum nitrate at 20℃ for 12 h, and the solid-liquid ratio was 1 g:5 mL; after the soaking was completed, the carrier was dried by microwave with a power of 800 W for 5 min to obtain a multifunctional Ni / Ce-Al2O3 precursor; the molar concentration of nickel element in the mixed solution of nickel nitrate, cerium nitrate, ammonium heptamolybdate and tetraammine platinum nitrate was 0.8 mol / L, the molar concentration of cerium element was 0.3 mol / L, the molar concentration of molybdenum element was 0.02 mol / L, and the molar concentration of platinum element was 0.002 mol / L;

[0078] S6: The multifunctional Ni / Ce-Al2O3 precursor was calcined at 350℃ in a hydrogen and nitrogen atmosphere for 1 h, and then was calcined at 500℃ for 3 h, and the calcination temperature increasing rate was controlled to be 2℃ / min, and the volume ratio of hydrogen to nitrogen was 1:4, to obtain a final high-strength micro-particle diameter methanation catalyst.

[0079] Example 2

[0080] Preparation of high-strength micro-particle diameter methanation catalyst

[0081] The preparation of high-strength micro-particle size methanation catalyst is substantially the same as that of Example 1, except that step S1 is different, specifically, 90 parts by mass of pseudo-boehmite and 10 parts by mass of α-Al2O3 are dispersed in 100 parts by mass of water, then 6 parts by mass of polyacrylic acid, 0.1 part by mass of 2-picolinic acid, and 1 part by mass of a NaNO3-KNO3 nitrate salt mixture are added to obtain a colloidal mixed solution.

[0082] Example 3

[0083] The preparation of high-strength micro-particle size methanation catalyst is substantially the same as that of Example 1, except that step S1 is different, specifically, 90 parts by mass of pseudo-boehmite and 10 parts by mass of α-Al2O3 are dispersed in 100 parts by mass of water, then 6 parts by mass of polyacrylic acid, 0.1 part by mass of 2-picolinic acid, and 1 part by mass of a NaNO3-KNO3 nitrate salt mixture are added to obtain a colloidal mixed solution.

[0084] The preparation of high-strength micro-particle size methanation catalyst is substantially the same as that of Example 1, except that step S1 is different, specifically, 90 parts by mass of pseudo-boehmite and 10 parts by mass of α-Al2O3 are dispersed in 100 parts by mass of water, then 6 parts by mass of polyacrylic acid, 0.1 part by mass of 2-picolinic acid, and 1 part by mass of a NaNO3-KNO3 nitrate salt mixture are added to obtain a colloidal mixed solution.

[0085] Example 4

[0086] The preparation of high-strength micro-particle size methanation catalyst is substantially the same as that of Example 1, except that step S1 is different, specifically, 90 parts by mass of pseudo-boehmite and 10 parts by mass of α-Al2O3 are dispersed in 100 parts by mass of water, then 6 parts by mass of polyacrylic acid, 0.1 part by mass of 2-picolinic acid, and 1 part by mass of a NaNO3-KNO3 nitrate salt mixture are added to obtain a colloidal mixed solution.

[0087] Example 5

[0088] The preparation of high-strength micro-particle size methanation catalyst is substantially the same as that of Example 1, except that step S1 is different, specifically, 90 parts by mass of pseudo-boehmite and 10 parts by mass of α-Al2O3 are dispersed in 100 parts by mass of water, then 6 parts by mass of polyacrylic acid, 0.1 part by mass of 2-picolinic acid, and 1 part by mass of a NaNO3-KNO3 nitrate salt mixture are added to obtain a colloidal mixed solution.

[0089] The preparation of high-strength micro-particle size methanation catalyst is substantially the same as that of Example 1, except that step S1 is different, specifically, 90 parts by mass of pseudo-boehmite and 10 parts by mass of α-Al2O3 are dispersed in 100 parts by mass of water, then 6 parts by mass of polyacrylic acid, 0.1 part by mass of 2-picolinic acid, and 1 part by mass of a NaNO3-KNO3 nitrate salt mixture are added to obtain a colloidal mixed solution.

[0090] Example 6

[0091] The preparation of high-strength micro-particle size methanation catalyst is substantially the same as that of Example 1, except that step S1 is different, specifically, 90 parts by mass of pseudo-boehmite and 10 parts by mass of α-Al2O3 are dispersed in 100 parts by mass of water, then 6 parts by mass of polyacrylic acid, 0.1 part by mass of 2-picolinic acid, and 1 part by mass of a NaNO3-KNO3 nitrate salt mixture are added to obtain a colloidal mixed solution.

[0092] The preparation of high-strength micro-particle size methanation catalyst is substantially the same as that of Example 1, except that step S1 is different, specifically, 90 parts by mass of pseudo-boehmite and 10 parts by mass of α-Al2O3 are dispersed in 100 parts by mass of water, then 6 parts by mass of polyacrylic acid, 0.1 part by mass of 2-picolinic acid, and 1 part by mass of a NaNO3-KNO3 nitrate salt mixture are added to obtain a colloidal mixed solution.

[0093] Example 7

[0094] Preparation of high-strength micro-particle size methanation catalyst:

[0095] The same as example 1, the difference is only that step S2 is different, specifically: the above colloidal mixed solution is stirred at high speed for 1 h to form a uniform colloid, and is naturally aged at 80°C for 4 h to obtain a precursor colloid.

[0096] Example 8

[0097] Preparation of high-strength micro-particle size methanation catalyst:

[0098] The same as example 1, the difference is only that step S5 is different, specifically: the above metal oxide carrier is first soaked in a mixed solution of nickel nitrate and zirconium nitrate at 60°C for 3 h, the solid-liquid ratio is 1 g:5 mL, the molar concentration of nickel element in the mixed solution of nickel nitrate and zirconium nitrate is 1.5 mol / L, and the molar concentration of zirconium element is 0.03 mol / L, after soaking, calcination is carried out under oxygen atmosphere at 300°C for 1 h, then soaking is carried out in a mixed solution of nickel nitrate, cerium nitrate, ammonium heptamolybdate and tetraammine platinum nitrate at 20°C for 12 h, the solid-liquid ratio is 1 g:5 mL, after soaking is completed, microwave drying is carried out at 800W for 5 min, to obtain a multifunctional Ni / Ce-Al2O3 precursor, wherein the molar concentration of nickel element in the mixed solution of nickel nitrate, cerium nitrate, ammonium heptamolybdate and tetraammine platinum nitrate is 0.8 mol / L, the molar concentration of cerium element is 0.3 mol / L, the molar concentration of molybdenum element is 0.02 mol / L, and the molar concentration of platinum element is 0.002 mol / L;

[0099] Example 9

[0100] Preparation of high-strength micro-particle size methanation catalyst:

[0101] The same as example 1, the difference is only that step S5 is different, specifically: the above metal oxide carrier is first soaked in a mixed solution of nickel nitrate and zirconium nitrate at 60°C for 3 h, the solid-liquid ratio is 1 g:5 mL, the molar concentration of nickel element in the mixed solution of nickel nitrate and zirconium nitrate is 1.5 mol / L, and the molar concentration of zirconium element is 0.03 mol / L, after soaking, calcination is carried out under oxygen atmosphere at 300°C for 1 h, then soaking is carried out in a mixed solution of nickel nitrate, cerium nitrate, ammonium heptamolybdate and tetraammine platinum nitrate at 20°C for 12 h, the solid-liquid ratio is 1 g:5 mL, after soaking is completed, microwave drying is carried out at 800W for 5 min, to obtain a multifunctional Ni / Ce-Al2O3 precursor, wherein the molar concentration of nickel element in the mixed solution of nickel nitrate, cerium nitrate, ammonium heptamolybdate and tetraammine platinum nitrate is 0.8 mol / L, the molar concentration of cerium element is 0.3 mol / L, the molar concentration of molybdenum element is 0.02 mol / L, and the molar concentration of platinum element is 0.002 mol / L;

[0102] Example 10

[0103] Preparation of high-strength micro-particle size methanation catalyst:

[0104] The same as example 1, the difference is only that step S5 is different, specifically: the above metal oxide carrier is first soaked in a mixed solution of nickel nitrate, yttrium nitrate and zirconium nitrate at 60°C for 3h, the solid-liquid ratio is: 1g:5mL, among which the molar concentration of nickel element in the mixed solution of nickel nitrate, yttrium nitrate and zirconium nitrate is 1.5mol / L, the molar concentration of yttrium element is 0.08mol / L, and the molar concentration of zirconium element is 0.03mol / L, after soaking, calcine under oxygen atmosphere at 300°C for 1h, then soak in a mixed solution of nickel nitrate, cerium nitrate and tetraammine platinum nitrate at 20°C for 12h, the solid-liquid ratio is: 1g:5mL, after soaking, dry for 5min under 800W microwave, get multifunctional Ni / Ce-Al2O3 precursor, among which the molar concentration of nickel element in the mixed solution of nickel nitrate, cerium nitrate and tetraammine platinum nitrate is 0.8mol / L, the molar concentration of cerium element is 0.3mol / L, and the molar concentration of platinum element is 0.002mol / L;

[0105] Example 11

[0106] Preparation of high-strength micro-particle size methanation catalyst:

[0107] The same as example 1, the difference is only that step S5 is different, specifically: the above metal oxide carrier is first soaked in a mixed solution of nickel nitrate, yttrium nitrate and zirconium nitrate at 60°C for 3h, the solid-liquid ratio is: 1g:5mL, among which the molar concentration of nickel element in the mixed solution of nickel nitrate, yttrium nitrate and zirconium nitrate is 1.5mol / L, the molar concentration of yttrium element is 0.08mol / L, and the molar concentration of zirconium element is 0.03mol / L, after soaking, calcine under oxygen atmosphere at 300°C for 1h, then soak in a mixed solution of nickel nitrate, cerium nitrate and tetraammine platinum nitrate at 20°C for 12h, the solid-liquid ratio is: 1g:5mL, after soaking, dry for 5min under 800W microwave, get multifunctional Ni / Ce-Al2O3 precursor, among which the molar concentration of nickel element in the mixed solution of nickel nitrate, cerium nitrate and tetraammine platinum nitrate is 0.8mol / L, the molar concentration of cerium element is 0.3mol / L, and the molar concentration of platinum element is 0.002mol / L;

[0108] Example 12

[0109] Preparation of high-strength micro-particle size methanation catalyst:

[0110] The preparation method of the high-strength micro-particle diameter methanation catalyst is substantially the same as that of Example 1, except that step S5 is different, specifically, the above metal oxide carrier is first soaked in a mixed solution of nickel nitrate, yttrium nitrate and zirconium nitrate at 60 DEG C for 3h, the solid-liquid ratio is 1g:5mL, the molar concentration of nickel element in the mixed solution of nickel nitrate, yttrium nitrate and zirconium nitrate is 1.5mol / L, the molar concentration of yttrium element is 0.08mol / L, and the molar concentration of zirconium element is 0.03mol / L, then the mixed solution of nickel nitrate, cerium nitrate, ammonium heptamolybdate and tetraammine platinum nitrate is soaked at 20 DEG C for 12h, the solid-liquid ratio is 1g:5mL, after the soaking is completed, the microwave drying is carried out at 800W for 5min, the multifunctional Ni / Ce-Al2O3 precursor is obtained, the molar concentration of nickel element in the mixed solution of nickel nitrate, cerium nitrate, ammonium heptamolybdate and tetraammine platinum nitrate is 0.8mol / L, the molar concentration of cerium element is 0.3mol / L, the molar concentration of molybdenum element is 0.02mol / L, and the molar concentration of platinum element is 0.002mol / L;

[0111] Comparative Example 1

[0112] Preparation of high-strength micro-particle diameter methanation catalyst

[0113] The preparation method of the high-strength micro-particle diameter methanation catalyst is substantially the same as that of Example 1, except that step S3 is different, and the steam pressure process is not carried out, specifically, the precursor colloid is kneaded and then put into an extrusion molding device for extrusion, the extrusion particle diameter is controlled to be 2mm, and the curing is carried out at 20 DEG C for 48h.

[0114] Comparative Example 2

[0115] Preparation of high-strength micro-particle diameter methanation catalyst

[0116] The preparation method of the high-strength micro-particle diameter methanation catalyst is substantially the same as that of Example 1, except that step S1 is different, and the pseudoboehmite is not added, specifically, 100 parts by mass of alpha-Al2O3 is dispersed in 100 parts by mass of water, then 5 parts by mass of aluminum nitrate, 1 part by mass of polyacrylic acid and 0.1 part by mass of 2-picolinic acid are added, and a colloid mixed solution is obtained.

[0117] Comparative Example 3

[0118] Preparation of high-strength micro-particle diameter methanation catalyst

[0119] The preparation method of the high-strength micro-particle diameter methanation catalyst is substantially the same as that of Example 1, except that step S1 is different, and the nitrate salt mixture is not added, specifically, 90 parts by mass of pseudoboehmite and 10 parts by mass of alpha-Al2O3 are dispersed in 100 parts by mass of water, then 5 parts by mass of aluminum nitrate, 0.1 part by mass of 2-picolinic acid and 1 part by mass of polyacrylic acid are added, and a colloid mixed solution is obtained.

[0120] Test Part

[0121] Take 500 mg of catalyst grinding to 40~60 mesh particle size, loaded into a stainless steel fixed bed reactor with a tube diameter of 10 mm, inert filler SiC is placed in the reactor to ensure uniform gas flow channel, keep the catalyst layer close but not compressed deformation.

[0122] Before the reaction, high-purity nitrogen is introduced at a flow rate of 300 mL / min, and the temperature is raised to 400℃ and kept for 30 min. After the bed temperature is stabilized, the nitrogen is switched to the raw gas for methanation reaction. The catalyst is stable under the reaction conditions for 30 min before sampling. The reaction outlet gas is analyzed by gas chromatography, and the inlet and outlet flow rates of the raw gas and the volume fraction of each component are recorded. Each catalyst is tested for five times of cycle.

[0123] The methanation reaction is set as follows:

[0124] Reaction temperature: 400℃

[0125] Reaction pressure: 0.1 MPa

[0126] Space velocity: 5,000 h -1

[0127] Feed gas (by volume fraction): CO2:H2:Ar=1:4:15

[0128] The gas chromatograph is set as follows:

[0129] Model: Agilent 7890

[0130] Detector: thermal conductivity detector

[0131] Chromatographic column: Porapak Q packed column (2 m x 4 mm, 80~100 mesh)

[0132]

[0133] Catalyst average mechanical strength test:

[0134] In the present application, the average mechanical strength test refers to taking 50 catalyst particles with complete appearance, no defects, cylindrical shape, average diameter of 2 mm to test the compressive strength, and calculating the average value. The compressive strength is measured by a strength tester.

[0135] Instrument: Multifunctional compressive strength tester HD-A513-C Haida instrument

[0136] Test conditions: 1 mm / min

[0137] Table 1

[0138]

[0139] According to Table 1, the average mechanical strength, CO2 first conversion rate and five-cycle CO2 conversion rate of the catalysts obtained in each of the examples are higher than those of each of the comparative examples, indicating that the methanation catalysts provided in the present patent have good average mechanical strength, catalytic activity and catalytic activity stability. The reason may be that in Comparative Example 1, the colloids are not subjected to autoclaving molding treatment, and the addition of the acid colloidal solvent and the nitrate salt mixture without autoclaving makes it difficult to form a dense and uniform crystal framework network, resulting in possible pore collapse during drying, which affects the mechanical properties, catalytic activity and catalytic activity stability. In Comparative Example 2, α-Al2O3 is used as the catalyst carrier, which usually has a lower specific surface area than pseudoboehmite and has a weaker ability to form a crosslinked network under the action of the acid colloidal solvent and the nitrate salt mixture. At the same time, the surface hydroxyl density of α-Al2O3 is low, and the interaction with the active components is weak, so the catalyst is prone to aggregation during loading, and the catalytic effect is weakened. Although the average mechanical strength is improved, the catalytic activity and catalytic stability are weaker. In Comparative Example 3, the nitrate salt mixture is lacking, and although a certain crosslinked network and uniform pore structure can be formed under the synergistic action of the acid colloidal solvent and autoclaving molding, the internal high ionic environment and mixed multi-cation system provided by the nitrate salt mixture are lacking, and the crystal growth is not well regulated, so the mechanical strength, catalytic activity and catalytic activity stability are all lower than those of the examples.

[0140] According to Examples 1 and 2, the composition of the catalyst carrier has a certain degree of influence on the mechanical strength, catalytic activity and catalytic activity stability of the catalyst. When a certain mass ratio of pseudoboehmite and α-Al2O3 is used, the catalytic activity and catalytic activity stability of the catalyst are better.

[0141] According to Examples 1, 3-6, the composition of the acid colloidal solvent has a certain degree of influence on the mechanical strength and catalytic activity of the catalyst. In Example 3, polyacrylic acid is lacking, the flexible network portion of the aging network is reduced, the toughness of the colloids is poor, and finally the carrier pores may be affected, reducing the mechanical strength. In Example 4, aluminum nitrate is lacking, which may cause the initial stability of the colloids to deteriorate, the particles to agglomerate, and thus the strength of the catalyst to be affected. In Example 5, 2-picolinic acid is lacking, the bridging effect between the organic network and the inorganic crystal is weakened, and the autoclaving recrystallization is affected. In Example 6, citric acid is used instead of nitrogen-containing heterocyclic carboxylic acid, and the system only has carboxylic acid complexation, lacking nitrogen-containing heterocyclic coordination ability. Therefore, when a certain proportion of aluminum salt, organic carboxylic acid polymer and nitrogen-containing heterocyclic carboxylic acid is used as the acid colloidal solvent, the mechanical strength, catalytic activity and catalytic activity stability of the catalyst are the best.

[0142] According to the embodiments 1, 7, it can be found that adjusting the aging process has certain influence on the catalytic activity and catalytic activity stability of the catalyst. The reason may be that in the embodiment 7, the natural heating aging is relied on, and in the absence of microwave-assisted heating, the internal temperature may be non-uniform, resulting in weak internal particle size uniformity. Therefore, the catalyst prepared by microwave-assisted heating to 80℃ aging has the best catalytic activity and catalytic activity stability.

[0143] According to the embodiments 1, 8-11, it can be found that adjusting the components of the impregnation solution has certain influence on the catalytic activity and catalytic activity stability of the catalyst. The reason may be that in the embodiment 8, Y 3+ ions are missing, which weakens the doping stability of the Al2O3 lattice, resulting in weakened sintering resistance of the catalyst core and decreased catalytic activity stability; in the embodiment 9, Zr 4+ ions are missing, and the system lacks physical blocking sites, so the resistance of Ni particles to migration and agglomeration at high temperature is small; in the embodiment 10, Mo 6 + is missing, which weakens the adsorption and activation ability of CO2, resulting in decreased catalytic ability; in the embodiment 11, Pt 4+ is missing, and the particle size of Ni particles may increase during reduction, and the particle size distribution is wider, which affects the distribution and stability of active sites. Therefore, when a suitable impregnation solution is used, the catalytic activity and catalytic activity stability of the catalyst are the best.

[0144] According to the embodiments 1, 12, it can be found that the absence of precalcination has certain influence on the catalytic activity and catalytic activity stability of the catalyst. The reason may be that after the absence of precalcination, the core-shell structure of the catalyst is missing, and the metal ions in the first impregnation and the second impregnation will diffuse and mix with each other, resulting in weakened stability of Y 3+ and Zr 4+ to the core in the first impregnation, and the inward migration of the second active component. Therefore, when precalcination is used to make the catalyst have a certain core-shell structure distribution, the catalytic activity and catalytic activity stability of the catalyst are the best

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for the preparation of a high strength, fine particle size methanation catalyst, characterized by, The method comprises the following steps: S1: dispersing a catalyst carrier, an acid colloidal solvent and a nitrate mixture in water to obtain a colloidal mixed solution; wherein the catalyst carrier comprises pseudo-boehmite, the nitrate mixture comprises at least two of potassium nitrate, sodium nitrate and lithium nitrate, the mass percentage of each component in the nitrate mixture is not less than 30%, and the acid colloidal solvent comprises an aluminum salt, an organic carboxylic acid polymer and a nitrogen-containing heterocyclic carboxylic acid, wherein the mass ratio of the aluminum salt, the organic carboxylic acid polymer and the nitrogen-containing heterocyclic carboxylic acid is 1:0.1-0.5:0.01-0.05; S2: performing aging treatment on the colloidal mixed solution to cross-link aluminum hydroxyl in the pseudo-boehmite under the action of the acid colloidal solvent and the nitrate mixture to form a network structure, thereby obtaining a precursor colloid, and the aging treatment conditions comprise: microwave heating at 300-800 W to 60-90°C, and then aging for 2-4 h; S3: performing kneading extrusion, autoclave molding and curing on the precursor colloid to cause the precursor to dissolve and recrystallize under the action of the nitrate mixture and autoclaving to form a crystal network structure, thereby obtaining precursor particles, and the autoclave molding and curing conditions comprise: treating at 0.8-1.5 MPa and 180-200°C for 12-24 h in a water vapor atmosphere, and then curing at 20-40°C for 40-48 h; S4: performing first calcination treatment on the precursor particles to cause the precursor to dehydrate and oxidize, thereby obtaining a metal oxide carrier; S5: immersing the metal oxide carrier in an active ion solution to load active ions on the metal oxide carrier, thereby obtaining a catalyst precursor; the active ion solution comprises a nickel salt, and the immersion treatment conditions comprise: first performing first-stage immersion treatment, then performing pre-calcination treatment, and then performing second-stage immersion treatment; S6: performing second calcination treatment on the catalyst precursor to activate the active ions on the metal oxide carrier to form active sites, thereby obtaining a high-strength micro-particle-size methanation catalyst.

2. The method of claim 1, wherein, The catalyst carrier further comprises α-Al2O3, and the mass ratio of the pseudo-boehmite to the α-Al2O3 is (3-10):

1.

3. The method of claim 1, wherein, The step S1 comprises: dispersing 80-100 parts by mass of the catalyst carrier, 5-15 parts by mass of the acid colloidal solvent and 0.5-3 parts by mass of the nitrate mixture in 80-100 parts by mass of water to obtain the colloidal mixed solution.

4. The method of claim 1, wherein, In the step S3, the kneading extrusion conditions comprise: kneading extrusion to obtain a cylindrical colloidal strip with a diameter of 1-3 mm.

5. The method of claim 1, wherein, The conditions of the first section of the immersion treatment in the step S5 include: immersion in the first immersion liquid at 60-80℃ for 2-4h; the first immersion liquid includes Ni 2+ , Y 3+ and Zr 4+ , wherein the concentration of Ni 2+ is 1.2-1.8mol / L, the concentration of Y 3+ is 0.05-0.1mol / L, and the concentration of Zr 4+ is 0.02-0.05mol / L; The pre-calcination treatment conditions comprise: calcination at 300-350°C for 0.5-1 h in an oxygen atmosphere; The second segment of the impregnation treatment includes: impregnating in a second impregnation solution at 20-40℃ for 12h, wherein the second impregnation solution includes Ni 2+ , rare earth metal ions, Mo 6+ , and Pt 4+ , wherein the concentration of Ni 2+ is 0.5-1.0mol / L, the concentration of the rare earth metal ions is 0.2-0.4mol / L, the rare earth metal ions include Ce 3+ , the concentration of Mo 6+ is 0.01-0.03mol / L, and the concentration of Pt 4+ is 0.001-0.005mol / L.

6. The method according to any one of claims 1 to 5, characterized in that, The method satisfies at least one of the following conditions: 1) the first calcination treatment conditions comprise: calcination treatment at 350-450°C for 2-4 h in an oxygen-containing atmosphere; 2) the second calcination treatment conditions comprise: calcination treatment at 350-450°C for 0.5-1 h in a hydrogen-containing and nitrogen-containing atmosphere, and then calcination treatment at 500-550°C for 2-3 h after temperature rising.

7. A high-strength, fine-particle diameter methanation catalyst characterized by, The method is prepared according to any one of claims 1-6.

8. A method of producing methane, characterized by, The method comprises: The carbon source and hydrogen are catalyzed by the high-strength micro-particle diameter methanation catalyst prepared by the method according to any one of claims 1-6 to obtain methane.

Images