Sulfur-tolerant methanation catalyst and preparation method thereof

Abstract

The invention discloses a sulfur-tolerant methanation catalyst which comprises the following components in percentage by mass: a carrier modifier, an active component, an auxiliary agent and a carrier, the invention also discloses a preparation method of the sulfur-tolerant methanation catalyst, which comprises the following steps: firstly, carrying out nitrogen doping treatment on the carbon nanotubes CNTs; secondly, mixing nitrate with Al2O3 and the nitrogen-doped carbon nanotube powder, carrying out precipitation reaction and roasting, dipping the obtained composite modified carrier in an ammonium thiomolybdate solution, and roasting to obtain a catalyst precursor; and finally, dipping in a mixed solution, roasting and passivating to obtain the sulfur-tolerant methanation catalyst. According to the invention, the composite carrier is adopted, so that the composite carrier has better dispersing performance and can promote the dispersion of the active components, and the adopted active auxiliary agent is also beneficial to dispersing and stabilizing the active components. The activity of the catalyst can be improved in sulfur-tolerant methanation reaction, the catalyst also has the characteristics of excellent heat-conducting property, electron transfer property and the like, and meanwhile, the low-temperature activity and high-temperature resistance of the catalyst are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and in particular relates to a sulfur-resistant methanation catalyst, and also relates to a preparation method of the sulfur-resistant methanation catalyst. Background Art

[0002] Methanation is the core technology of coal-to-gas substitution. The methanation catalyst is a nickel-based metal catalyst, which is sensitive to sulfides. In order to meet the H / C modulus requirements of the catalyst and methanation reaction, the traditional route must first partially transform the gasified syngas to obtain a syngas with a suitable H / C modulus, and then pass it through a purification device, usually a low-temperature methanol washing technology to remove the sulfides and carbon dioxide in the syngas. The process is cumbersome and the investment is increased. At the same time, the syngas undergoes a high temperature (transformation)-low temperature (low-temperature methanol washing)-high temperature (methanation) process, resulting in unreasonable energy distribution, commonly known as the "cold and hot disease" problem. In addition, the methanation reaction is a highly exothermic reaction. The reactors used in the methanation technology of existing industrial devices are all adiabatic fixed bed reactors. In order to quickly remove the reaction heat and ensure that the reaction temperature rise is not too high, part of the product gas is circulated to achieve the purpose of controlling the reaction temperature. Typical methanation technologies include David methanation technology and Topsoe methanation technology. Since the entire natural gas production process needs to go through coal gasification, dust removal and oil removal, sulfur-resistant conversion, desulfurization and decarbonization before the methane synthesis stage, it has to go through a process of high temperature, low temperature, and high temperature again, and the energy utilization efficiency is poor, resulting in complex processes, large investments, and high energy consumption.

[0003] In recent years, sulfur-resistant methane synthesis technology has become a hot topic of research. Since the raw gas used in this process does not need to be desulfurized, the catalyst usually has the dual functions of methanation and conversion, which reduces the process's requirements for the hydrogen-carbon ratio of the raw gas, thereby greatly simplifying the process flow and achieving the goal of energy saving and consumption reduction. The catalyst used in sulfur-resistant methane synthesis technology is mainly a molybdenum-based catalyst, which is a multifunctional catalyst with Mo as the active component. Co, Ni, K, La, W, etc. are usually added as co-catalysts. The sulfur-resistant methanation process uses a sulfur-resistant catalyst. The biggest advantage is that the raw gas does not need to be desulfurized, and the two reactions of methanation and CO conversion are carried out simultaneously on the same catalyst. There is no need to add water vapor to adjust the H2 / CO ratio, thereby simplifying the process flow and reducing energy consumption. Its heat consumption is reduced by nearly 40% compared with traditional processes.

[0004] Sulfur-resistant methanation uses a sulfur-resistant Mo-based catalyst, which has both water gas shift and methanation functions. Therefore, water gas shift and methanation can be carried out in the same reactor. The synthesis gas from coal gasification directly enters the methanation reactor and undergoes a direct methanation reaction. Compared with the traditional non-sulfur-resistant methanation process, the sulfur-resistant methanation process has the following characteristics: (1) The acid gas purification process is after the methanation process. Since the methanation reaction is a molecular reduction reaction, the gas processing volume is significantly reduced, reducing the process load such as low-temperature methanol washing; (2) Avoid energy waste caused by cooling the raw gas first and then heating it before and after the acid gas removal step; (3) 20mg / m 3 H2S exists, so the purification process does not need to absorb H2S to less than 0.1×10 -6 , process requirements and corresponding operating costs are reduced; (4) the water vapor conversion process is eliminated, reducing equipment investment and operating costs.

[0005] Sulfur-tolerant methanation catalysts mainly need to solve the problems of high activity and high selectivity under low temperature conditions, as well as the stability of the catalyst. Therefore, providing a sulfur-tolerant methanation catalyst with high activity, good stability, long service life, simple preparation method, and a wide temperature range (300-650°C) with both high activity and stability has become an urgent problem to be solved by those skilled in the art. Summary of the invention

[0006] The object of the present invention is to provide a sulfur-resistant methanation catalyst having high low-temperature activity and good stability.

[0007] Another object of the present invention is to provide a method for preparing a sulfur-resistant methanation catalyst.

[0008] The technical solution adopted by the present invention is that the sulfur-resistant methanation catalyst includes 3-10% carrier modifier, 10-30% active component, 0.5-3% auxiliary agent, and the balance is carrier, and the mass percentage of the above components is 100%. The carrier includes Al2O3, ZrO2 and nitrogen-doped carbon nanotubes; the content of Al2O3-ZrO2 is 55-85% of the total mass of the catalyst, and the mass ratio of Al2O3 to ZrO2 is 5-15:1; the content of nitrogen-doped carbon nanotubes is 5-30% of the total mass of the catalyst. The carrier modifier is Ce and Mn, the active component is MoS2, and the auxiliary agent is Fe3P.

[0009] Another technical solution adopted by the present invention is a method for preparing a sulfur-resistant methanation catalyst, which is specifically implemented according to the following steps: Step 1, performing nitrogen doping treatment on carbon nanotubes CNTs to obtain nitrogen-doped carbon nanotubes; Step 2, mixing aluminum nitrate solution, zirconium nitrate solution, cerium nitrate solution, manganese nitrate solution with Al2O3 and nitrogen-doped carbon nanotube powder, stirring evenly, dropping sodium carbonate solution into the mixture for precipitation reaction, washing, filtering, drying and calcining to obtain a composite modified carrier powder; Step 3, grinding and sieving the composite modified carrier powder, then mixing it with water, pressing it into a shape, and drying it to obtain a composite modified carrier; Step 4, immersing the composite modified support in an ammonium thiomolybdate solution, drying, and calcining to obtain a catalyst precursor A; Step 5, immersing the catalyst precursor A in the mixed solution, adjusting the solution pH to 3-6, drying, calcining under a nitrogen atmosphere, then cooling under a nitrogen atmosphere, and then passing an oxygen-nitrogen mixed gas for passivation treatment, washing the obtained thermal decomposition product with ammonia water, and then washing with deionized water to neutrality, and drying to obtain a sulfur-resistant methanation catalyst.

[0010] The present invention is also characterized in that: In step 1, specifically: placing carbon nanotubes CNTs in a tubular furnace and introducing an ammonia-nitrogen mixed gas for heat treatment, wherein the volume fraction of ammonia in the mixed gas is 50%-90%, to obtain nitrogen-doped carbon nanotubes; the heat treatment temperature is 500-800°C, and the heat treatment time is 3-10h.

[0011] In step 2, the precipitation reaction temperature is 50-90° C., and the time is 30-200 min; the calcination temperature is 300-600° C., and the time is 4-12 h.

[0012] In step 4, the impregnation time is 10-20 hours, the mixture is dried at 110°C for 10 hours, and the mixture is calcined at a temperature of 500-600°C for 3-5 hours. In step 5, the mixed solution is prepared by mixing Fe3P, ferric hypophosphite solution and ammonium hypophosphite solution; the molar ratio of ferric hypophosphite to ammonium hypophosphite is 1:0.5-3; and the content of Fe3P is 1-2% of the mass of the mixed solution.

[0013] In step 5, the impregnation time is 10-20 hours, the calcination temperature is 300-600° C., the calcination time is 3-10 hours, and the passivation treatment time is 12 hours.

[0014] The beneficial effects of the present invention are as follows: the sulfur-resistant methanation catalyst of the present invention uses ZrO2-Al2O3 and nitrogen-doped carbon nanotubes as composite carriers, the addition of ZrO2 improves the electron transfer ability and acidity of the Al2O3 carrier, the surface of the nitrogen-doped carbon nanotubes can adsorb a large amount of hydrogen, which is transferred to the active sites on the catalyst surface to increase the rate of the hydrogenation reaction, and the Ce and Mn modifications are beneficial to improving the adsorption performance of CO. Furthermore, the composite carrier used in the present invention has good dispersibility, which can promote the dispersion of the active component MoS2, and the active additive Fe3P used is also helpful to disperse and stabilize the active component. It is beneficial to improve the activity of the catalyst in the sulfur-resistant methanation reaction, and also has the characteristics of excellent thermal conductivity and electron transfer performance, while improving the low-temperature activity and high-temperature resistance of the catalyst; the hydrophobicity of the nitrogen-doped carbon nanotubes is beneficial to desorbing the water produced after the methanation of carbon dioxide, thereby promoting the forward reaction, the reaction activation temperature is low, and it has good low-temperature reaction activity, which is particularly suitable for methanation heat transfer reactors, and can effectively reduce the reactor equipment investment and operating costs. At the same time, after nitrogen-doped carbon nanotubes were introduced into the catalyst, active carbon sites were formed on the catalyst surface. The mesoporous channels of the nanotubes were conducive to heat and mass transfer, and nitrogen doping promoted the electron mobility on the surface. The formed carbon sites inhibited the generation and further expansion of carbon deposits, thereby improving the catalyst's anti-carbon deposition performance. DETAILED DESCRIPTION

[0015] The present invention is described in detail below in conjunction with specific implementation modes.

[0016] The sulfur-resistant methanation catalyst of the present invention comprises, based on the total mass percentage of the catalyst, 3-10% of a carrier modifier, 10-30% of an active component, 0.5-3% of an additive, and the remainder is a carrier, and the mass percentage of the above components is 100%; The carrier includes Al2O3, ZrO2 and nitrogen-doped carbon nanotubes; the content of Al2O3-ZrO2 is 55-85% of the total mass of the catalyst, and the mass ratio of Al2O3 to ZrO2 is 5-15:1; the content of nitrogen-doped carbon nanotubes is 5-30% of the total mass of the catalyst; The carrier modifiers are Ce and Mn, wherein the mass ratio of CeO2 to MnO2 is 1-3:1; The active component is MoS2 and the auxiliary agent is Fe3P; Carbon nanotubes (CNTs) are one-dimensional nanomaterials with a graphite-like wall structure. 2-C can adsorb a large amount of hydrogen and transfer it to the active sites on the catalyst surface, thereby increasing the rate of the hydrogenation reaction. Carbon nanotubes have a developed mesoporous structure, which is beneficial to the molecular diffusion of reactants and products, and is also beneficial to the transfer of reaction heat. Nitrogen doped in carbon nanotubes is more conducive to promoting electron transfer and improving the reduction ability of the catalyst. Nitrogen doping is beneficial to the loading and dispersion of active components.

[0017] The present invention uses Ce and Mn modified alumina-zirconia-nitrogen doped carbon nanotubes as a composite carrier, loads MoS2 and Fe3P, and forms a sulfur-resistant methanation catalyst. The catalyst has a large specific surface area, high strength, excellent low-temperature activity, and good high-temperature stability. Compared with traditional sulfur-resistant methanation catalysts, it has high CO conversion rate and CH4 selectivity, and the preparation method is simple, which has industrial application prospects.

[0018] The method for preparing the sulfur-resistant methanation catalyst of the present invention is specifically implemented according to the following steps: Step 1, using ammonia to perform nitrogen doping treatment on carbon nanotubes CNTs to obtain nitrogen-doped carbon nanotubes; Specifically, carbon nanotubes (CNTs) are placed in a tube furnace and introduced into an ammonia-nitrogen mixed gas for heat treatment, wherein the volume fraction of ammonia in the mixed gas is 50%-90%, to obtain nitrogen-doped carbon nanotubes; The heat treatment temperature is 500-800°C and the heat treatment time is 3-10h; Step 2, mixing aluminum nitrate solution, zirconium nitrate solution, cerium nitrate solution, manganese nitrate solution with Al2O3 and nitrogen-doped carbon nanotube powder, stirring evenly, dropping sodium carbonate solution into precipitation reaction, controlling the endpoint pH of the precipitation reaction mixed solution to be 7.0-8.5, washing, filtering, drying and calcining after the reaction is completed to obtain a composite modified carrier powder; The particle size of Al2O3 and nitrogen-doped CNTs powders ranged from 100 to 400 mesh; The precipitation reaction temperature is 50-90°C and the time is 30-200 minutes; The calcination temperature is 300-600°C and the time is 4-12h; Step 3, grinding and sieving the composite modified carrier powder to obtain a fine powder mixture, and then mixing it with water, pressing and molding, and drying to obtain a composite modified carrier; Step 4, immersing the composite modified support in an ammonium thiomolybdate solution for 10-20 hours, drying at 110° C. for 10 hours, and calcining at a temperature of 500-600° C. for 3-5 hours to obtain a catalyst precursor A; The mass fraction of ammonium thiomolybdate solution is 22% to 23%; Step 5, immersing the catalyst precursor A in the mixed solution, and adjusting the solution pH to 3-6 with hypophosphorous acid or ammonia water, the immersion time is 10-20 hours, drying, calcining in a nitrogen atmosphere, the calcination temperature is 300-600°C, the calcination time is 3-10 hours, then cooling to 20°C in a nitrogen atmosphere, and then passing an oxygen-nitrogen mixed gas for passivation treatment for 12 hours, washing the obtained thermal decomposition product with 0.5%-10% ammonia water by mass, and then washing with deionized water until neutral, and drying to obtain a sulfur-resistant methanation catalyst.

[0019] The mixed solution is formed by mixing Fe3P, ferric hypophosphite solution and ammonium hypophosphite solution; The molar ratio of ferric hypophosphite to ammonium hypophosphite is 1:0.5-3; The content of Fe3P is 1-2% of the mixed liquid mass.

[0020] A sulfur-resistant methanation method, wherein a methanation reaction is carried out in a synthesis gas raw material containing hydrogen sulfide, and a sulfur-resistant methanation catalyst is used, wherein the reaction temperature is 300-600°C, the reaction pressure is 1.0-5.0 MPa, and the reaction space velocity is 5000-10000 h -1 The hydrogen sulfide content in the raw gas is 0.1%-2.0%, and the hydrogen-carbon ratio is 1-3:1.

[0021] Example 1 Take 20g CNTs powder, pass nitrogen containing 5% ammonia for high temperature heat treatment, the space velocity is 10000, the heat treatment temperature is 600℃, and the treatment time is 3h; 43.27 g of aluminum nitrate nonahydrate, 17.44 g of zirconium nitrate pentahydrate, 8.66 g of manganese nitrate tetrahydrate and 2.52 g of cerium nitrate hexahydrate were weighed and dissolved in 1000 mL of deionized water, and heated to 50°C in a constant temperature reactor. 49.12 g of Al2O3 and 12 g of CNTs powder were added, stirred and 0.05 g / mL of sodium carbonate solution was slowly added dropwise for precipitation reaction. The end point pH value was controlled to be 7.0. After aging for 2 h, the precipitate was washed, filtered, and dried at 110°C for 8 h, and then calcined at 500°C in nitrogen for 4 h to obtain a composite modified carrier powder.

[0022] 76g of the composite modified carrier powder was taken, and 100g of ammonium molybdate solution containing 22% of MoS2 by mass was added for impregnation, dried at 110°C for 10h, and calcined at 550°C for 3h to obtain catalyst precursor A. 98g of catalyst precursor A was impregnated with 100g of an acidic aqueous solution of ferric hypophosphite and ammonium hypophosphite containing 2% of Fe3P by mass, wherein the molar ratio of ferric hypophosphite to ammonium hypophosphite was 1:0.8, and the pH value of the solution was 4 (adjusted with hypophosphorous acid or ammonia water). After impregnation, catalyst precursor B was obtained, and B was heated to 350°C and calcined for 8h in a nitrogen atmosphere, then cooled to 20°C in a nitrogen atmosphere, and then nitrogen containing 1% of oxygen by volume was introduced for passivation treatment for 12h. The thermal decomposition product was washed with ammonia water (3%), and then washed with deionized water until neutral, and dried at 110°C to obtain the catalyst. Example 2 Take 20g CNTs powder, introduce nitrogen containing 5% ammonia for high-temperature heat treatment, the space velocity is 10000, the heat treatment temperature is 600℃, and the treatment time is 3h.

[0023] 43.27 g of aluminum nitrate nonahydrate, 17.44 g of zirconium nitrate pentahydrate, 8.66 g of manganese nitrate tetrahydrate and 2.52 g of cerium nitrate hexahydrate were weighed and dissolved in 1000 mL of deionized water, and heated to 60°C in a constant temperature reactor. 51.12 g of Al2O3 and 10 g of CNTs powder were added, and 0.05 g / mL of sodium carbonate solution was slowly added dropwise while stirring for precipitation reaction. The end point pH value was controlled to be 8.0. After aging for 2 h, the precipitate was washed, filtered, and dried at 110°C for 8 h, and then calcined at 500°C in a nitrogen atmosphere for 4 h to obtain a composite modified carrier powder.

[0024] 76g of the composite modified carrier powder was taken, and 100g of ammonium molybdate solution containing 22% of MoS2 by mass was added for impregnation, dried at 110°C for 10h, and calcined at 550°C for 3h to obtain catalyst precursor A. 98g of catalyst precursor A was impregnated with 100g of an acidic aqueous solution of ferric hypophosphite and ammonium hypophosphite containing 2% of Fe3P by mass, wherein the molar ratio of ferric hypophosphite to ammonium hypophosphite was 1:0.8, and the pH value of the solution was 4 (adjusted with hypophosphorous acid or ammonia water). After impregnation, catalyst precursor B was obtained, and B was heated to 350°C and calcined for 8h in a nitrogen atmosphere, then cooled to 20°C in a nitrogen atmosphere, and then nitrogen containing 1% of oxygen by volume was introduced for passivation treatment for 12h. The thermal decomposition product was washed with ammonia water (3%), and then washed with deionized water until neutral, and dried at 110°C to obtain the catalyst.

[0025] Example 3 Take 20g CNTs powder, introduce nitrogen containing 5% ammonia for high-temperature heat treatment, the space velocity is 10000, the heat treatment temperature is 600℃, and the treatment time is 3h.

[0026] 43.27 g of aluminum nitrate nonahydrate, 17.44 g of zirconium nitrate pentahydrate, 8.66 g of manganese nitrate tetrahydrate and 2.52 g of cerium nitrate hexahydrate were weighed and dissolved in 1000 mL of deionized water, and heated to 70°C in a constant temperature reactor. 49.12 g of Al2O3 and 12 g of CNTs powder were added, and 0.05 g / mL of sodium carbonate solution was slowly added dropwise while stirring for precipitation reaction. The end point pH value was controlled to be 8.5. After aging for 2 h, the precipitate was washed, filtered, and dried at 110°C for 8 h, and then calcined at 500°C in a nitrogen atmosphere for 4 h to obtain a composite modified carrier powder.

[0027] 76g of the composite modified carrier powder was taken, and 100g of ammonium molybdate solution containing 23% of MoS2 by mass was added for impregnation, dried at 110°C for 10h, and calcined at 550°C for 3h to obtain catalyst precursor A. 98g of catalyst precursor A was impregnated with 100g of an acidic aqueous solution of ferric hypophosphite and ammonium hypophosphite containing 1% of Fe3P by mass, wherein the molar ratio of ferric hypophosphite to ammonium hypophosphite was 1:0.8, and the pH value of the solution was 4 (adjusted with hypophosphorous acid or ammonia water). After impregnation, catalyst precursor B was obtained, and B was heated to 350°C and calcined for 8h in a nitrogen atmosphere, then cooled to 20°C in a nitrogen atmosphere, and then nitrogen containing 1% of oxygen by volume was introduced for passivation treatment for 12h. The thermal decomposition product was washed with ammonia water (3%), and then washed with deionized water until neutral, and dried at 110°C to obtain the catalyst.

[0028] Example 4 Take 20g CNTs powder, introduce nitrogen containing 5% ammonia for high-temperature heat treatment, the space velocity is 10000, the heat treatment temperature is 600℃, and the treatment time is 3h.

[0029] 43.27 g of aluminum nitrate nonahydrate, 24.4 g of zirconium nitrate pentahydrate, 8.66 g of manganese nitrate tetrahydrate and 2.52 g of cerium nitrate hexahydrate were weighed and dissolved in 1000 mL of deionized water, and heated to 70°C in a constant temperature reactor. 49.12 g of Al2O3 and 10 g of CNTs powder were added, and 0.05 g / mL of sodium carbonate solution was slowly added dropwise while stirring for precipitation reaction. The end point pH value was controlled to be 7.0. After aging for 2 h, the precipitate was washed, filtered, and dried at 110°C for 8 h, and then calcined at 500°C in a nitrogen atmosphere for 4 h to obtain a composite modified carrier powder.

[0030] 76g of the composite modified carrier powder was taken, and 100g of ammonium molybdate solution containing 22% of MoS2 by mass was added for impregnation, dried at 110°C for 10h, and calcined at 550°C for 3h to obtain catalyst precursor A. 98g of catalyst precursor A was impregnated with 100g of an acidic aqueous solution of ferric hypophosphite and ammonium hypophosphite containing 2% of Fe3P by mass, wherein the molar ratio of ferric hypophosphite to ammonium hypophosphite was 1:0.8, and the pH value of the solution was 4 (adjusted with hypophosphorous acid or ammonia water). After impregnation, catalyst precursor B was obtained, and B was heated to 350°C and calcined for 8h in a nitrogen atmosphere, then cooled to 20°C in a nitrogen atmosphere, and then nitrogen containing 1% of oxygen by volume was introduced for passivation treatment for 12h. The thermal decomposition product was washed with ammonia water (3%), and then washed with deionized water until neutral, and dried at 110°C to obtain the catalyst.

[0031] Comparative Example 1 Compared with Example 1, no auxiliary nitrogen-doped carbon nanotubes are added to the carrier in this example.

[0032] Comparative Example 2 Compared with Example 1, the catalyst carrier in this example does not contain zirconium oxide.

[0033] Comparative Example 3 Compared with Example 1, no Fe3P is added to the catalyst promoter in this example.

[0034] Catalyst Evaluation: The catalyst was tested in a pressurized adiabatic fixed bed reactor with a catalyst loading of 20 ml; The catalyst needs to be pre-sulfurized before activity evaluation. The pre-treatment conditions are: sulfurization treatment at 450°C for 5 hours in a hydrogen atmosphere containing 1% hydrogen sulfide. The catalyst activity test results are shown in Table 1. Evaluation conditions: reaction space velocity 8000h -1 ; Reaction pressure 3MPa, inlet temperature 400-600℃; Raw gas composition (volume percentage): H2 / CO is 1:1, H2 and CO content is 40%, 1% H2S, and the rest is nitrogen.

[0035] Table 1 Catalyst activity test results

[0036] As can be seen from Table 1, compared with the comparative examples, the catalysts in Examples 1 to 4 have better sulfur-resistant methanation activity. From the evaluation results of Example 1 and Comparative Examples 1-3, the addition of nitrogen-doped carbon nanotubes, zirconium oxide, and Fe3P has a certain effect on improving the activity of the catalyst, especially the use of nitrogen-doped carbon nanotubes and zirconium oxide modification can significantly improve the activity of the catalyst.

[0037] In addition, the catalysts prepared in Examples 1 to 4 did not break or shed powder when unloaded after the reaction, indicating that the catalysts had good strength.

Claims

1. A sulfur-resistant methanation catalyst, characterized in that: Calculated by the total mass percentage of the catalyst, it includes 3-10% of a carrier modifier, 10-30% of an active component, 0.5-3% of an auxiliary agent, and the remainder is a carrier. The mass percentage of the above components is 100%.

2. The sulfur-resistant methanation catalyst according to claim 1, characterized in that The carrier comprises Al2O3, ZrO2 and nitrogen-doped carbon nanotubes; the content of Al2O3-ZrO2 is 55-85% of the total mass of the catalyst, the mass ratio of Al2O3 to ZrO2 is 5-15:1; the content of nitrogen-doped carbon nanotubes is 5-30% of the total mass of the catalyst.

3. The sulfur-resistant methanation catalyst according to claim 1, characterized in that The carrier modifiers are Ce and Mn, the active component is MoS2, and the auxiliary agent is Fe3P.

4. A method for preparing a sulfur-resistant methanation catalyst, characterized in that: Follow the steps below to implement it: Step 1, performing nitrogen doping treatment on carbon nanotubes CNTs to obtain nitrogen-doped carbon nanotubes; Step 2, mixing aluminum nitrate solution, zirconium nitrate solution, cerium nitrate solution, manganese nitrate solution with Al2O3 and nitrogen-doped carbon nanotube powder, stirring evenly, dropping sodium carbonate solution into the mixture for precipitation reaction, washing, filtering, drying and calcining to obtain a composite modified carrier powder; Step 3, grinding and sieving the composite modified carrier powder, then mixing it with water, pressing it into a shape, and drying it to obtain a composite modified carrier; Step 4, immersing the composite modified support in an ammonium thiomolybdate solution, drying, and calcining to obtain a catalyst precursor A; Step 5, immersing the catalyst precursor A in the mixed solution, adjusting the solution pH to 3-6, drying, calcining under a nitrogen atmosphere, then cooling under a nitrogen atmosphere, and then passing an oxygen-nitrogen mixed gas for passivation treatment, washing the obtained thermal decomposition product with ammonia water, and then washing with deionized water to neutrality, and drying to obtain a sulfur-resistant methanation catalyst.

5. The method for preparing the sulfur-resistant methanation catalyst according to claim 4, characterized in that: In the step 1, specifically: placing carbon nanotubes CNTs in a tubular furnace and introducing an ammonia-nitrogen mixed gas for heat treatment, wherein the volume fraction of ammonia in the mixed gas is 50%-90%, to obtain nitrogen-doped carbon nanotubes; the heat treatment temperature is 500-800°C, and the heat treatment time is 3-10h.

6. The method for preparing the sulfur-resistant methanation catalyst according to claim 4, characterized in that: In the step 2, the precipitation reaction temperature is 50-90° C., and the time is 30-200 min; the roasting temperature is 300-600° C., and the time is 4-12 h.

7. The method for preparing the sulfur-resistant methanation catalyst according to claim 4, characterized in that: In the step 4, the impregnation time is 10-20 hours, the drying is carried out at 110° C. for 10 hours, and the calcination is carried out at a temperature of 500-600° C. for 3-5 hours.

8. The method for preparing the sulfur-resistant methanation catalyst according to claim 4, characterized in that: In step 5, the mixed solution is formed by mixing Fe3P, ferric hypophosphite solution and ammonium hypophosphite solution; the molar ratio of ferric hypophosphite to ammonium hypophosphite is 1:0.5-3; and the content of Fe3P is 1-2% of the mass of the mixed solution.

9. The method for preparing the sulfur-resistant methanation catalyst according to claim 4, characterized in that: In the step 5, the impregnation time is 10-20 hours, the calcination temperature is 300-600° C., the calcination time is 3-10 hours, and the passivation treatment time is 12 hours.

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