Methanation catalyst, its preparation method and use

Abstract

The application relates to the technical field of high polymer materials, and provides a methanation catalyst as well as a preparation method and application thereof.The methanation catalyst comprises a zeolite molecular sieve as a carrier, NiO as an active component, CeO2 as a first additive and Co3O4 as a second additive.The methanation catalyst provided by the application has the advantages of simple preparation process, no waste liquid discharge in the preparation process, green environmental protection, easy operation, replacement of expensive noble metals by low-cost transition metals, reduced catalyst production cost, preparation and reduction process of the catalyst meeting the requirements of energy saving and consumption reduction, market economic competitive advantages, and facilitation of industrialized production.Meanwhile, the methanation catalyst provided by the application has the advantages of high CO conversion rate, high CH4 selectivity and yield, good low-temperature reaction activity and stability, and is suitable for industrialized production.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a methanation catalyst, its preparation method, and its application. Background Technology

[0002] Coal-to-natural gas technology is a way to achieve high thermal efficiency in the clean conversion and utilization of coal. Compared with other coal chemical technologies, it has the advantages of simple process, low investment cost, high conversion rate and less pollutants generated. It can directly convert coal into natural gas that is easy to transport locally, effectively saving the transportation cost of natural gas.

[0003] The core of coal-to-natural-gas processes is methanation technology. Methanation is a strongly exothermic reaction, which easily leads to catalyst sintering and deactivation, reducing catalyst activity. Therefore, developing catalysts with high activity, high selectivity, and high stability is a key research focus in CO methanation technology.

[0004] CO methanation catalysts are mainly supported catalysts, with commonly used active components being transition metals Ni, Fe, and Co, and noble metals Ru and Rh. Common oxide supports include Al₂O₃, SiO₂, TiO₂, ZrO₂, MgO, and CeO₂. Ru-based catalysts exhibit high catalytic activity and selectivity in low-temperature methanation reactions, but their high cost limits their industrial applications. Among transition metals, Ni-based catalysts have become the mainstream methanation catalyst due to their wide availability, low cost, and high catalytic activity.

[0005] CN104549291B discloses a nickel-aluminum methanation catalyst, using Al2O3 as a support and Ni as the active component. A stepwise calcination method is employed to improve the catalyst's thermal stability. The reduction temperature of this catalyst is 600-800 °C. ℃This method significantly increases energy consumption, thereby raising production costs and hindering energy conservation and emission reduction, thus limiting its industrial application. CN108295857A discloses a highly stable nickel-based methanation catalyst, using Al2O3 as a support, Ni as the active component, and Sr as a promoter. The preparation process incorporates long-chain organic compounds containing ether bonds. The precursor is first decomposed and pre-calcined in air, then heat-treated at 900°C for 4 hours in an air atmosphere. The resulting catalyst is then reduced at 850°C for 3 hours to obtain a highly stable catalyst. However, this method also suffers from high energy consumption. CN107029726B discloses a nano-nickel-based CO methanation catalyst, using SiO2 as a support, Ni as the active component, and La, Ce, and Zr as promoters. A carbon source is added, and the catalyst utilizes the confinement effect of the support pores and the isolation effect of the surface carbon to prevent the active component from agglomerating at high temperatures and improve the dispersion. However, this catalyst requires stepwise calcination in an inert atmosphere and air, which increases the preparation cost of the catalyst. Furthermore, the conversion rate of this catalyst is only about 92% at reaction temperatures as high as 300℃, and the low-temperature reaction activity of this catalyst needs to be improved.

[0006] Therefore, for CO methanation catalysts, developing a catalyst with good low-temperature reactivity, high stability, and low cost is of great significance. It meets the current requirements for energy conservation and emission reduction and is conducive to industrial application. Summary of the Invention

[0007] The purpose of this invention is to provide a methanation catalyst to solve the technical problems of high preparation cost, poor low-temperature reactivity, and poor stability of existing methanation catalysts.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention proposes a methanation catalyst comprising a zeolite molecular sieve as a support, NiO as an active component, CeO2 as a first promoter and Co3O4 as a second promoter.

[0010] The methanation catalyst provided by this invention uses zeolite molecular sieve as a support, which has a large specific surface area. The active components can be highly dispersed on the surface of the support, reducing the crystal size of the active components, preventing agglomeration, improving the reduction performance of the catalyst, and lowering the reduction temperature of the catalyst. In the CO methanation reaction, the large specific surface area helps CO and H2 to have sufficient contact, thereby improving the catalytic activity and stability of the CO methanation reaction.

[0011] The first auxiliary agent, CeO2, has good oxygen storage and release functions. 4+ / Ce 3+Redox pairs help promote NiO reduction, improve the reduction performance of the catalyst, lower the reduction temperature, and avoid problems such as high energy consumption and catalyst agglomeration caused by high temperatures.

[0012] The second promoter, Co3O4, has good low-temperature oxidation activity, which helps to improve the low-temperature methanation reaction activity of the catalyst, thereby greatly reducing the reaction temperature of the catalyst, avoiding the agglomeration of active components caused by high-temperature reaction, and improving the stability of the catalyst.

[0013] There is a strong interaction between the active component and the promoter, which enhances the adsorption capacity of CO and H2 on the catalyst surface, thereby improving the low-temperature reaction activity of CO methanation and the stability of the catalyst. It can also effectively reduce the reduction temperature, reduce the production cost of the catalyst, and meet the requirements of energy conservation and consumption reduction.

[0014] According to some embodiments of the present invention, the mass ratio of the carrier, active component, first adjuvant, and second adjuvant is 1:(0.06-0.26):(0.01-0.15):(0.01-0.15).

[0015] According to some embodiments of the present invention, the zeolite molecular sieve is at least one of ZSM-5 molecular sieve, Y molecular sieve, and 13X molecular sieve.

[0016] Secondly, the present invention provides a method for preparing the above-mentioned catalyst, comprising:

[0017] A mixed metal salt aqueous solution containing an active component precursor, a first auxiliary agent precursor, and a second auxiliary agent precursor was prepared; the support was impregnated with the mixed metal salt aqueous solution, dried, and calcined to obtain the catalyst.

[0018] According to some embodiments of the present invention, the impregnation is performed using an ultrasonic-assisted equal-volume impregnation method. Preferably, this includes adding an equal volume of a mixed metal salt aqueous solution to a carrier and then subjecting it to ultrasonic treatment.

[0019] The ultrasonic-assisted equal-volume impregnation method can improve the full dispersion of active components on the carrier surface and avoid the aggregation and growth of active component grains.

[0020] According to some embodiments of the present invention, the active component precursor is nickel nitrate and / or nickel acetate, preferably nickel nitrate.

[0021] According to some embodiments of the present invention, the first auxiliary agent precursor is at least one of cerium nitrate, cerium sulfate, and cerium chloride, preferably cerium nitrate.

[0022] According to some embodiments of the present invention, the second auxiliary agent precursor is at least one of cobalt nitrate, cobalt sulfate, and cobalt chloride, preferably cobalt nitrate.

[0023] According to some embodiments of the present invention, the molar ratio (in terms of metal) of the active component precursor, the first auxiliary agent precursor, and the second auxiliary agent precursor is 1:(0.02-0.90):(0.05-1.90).

[0024] According to some embodiments of the present invention, the drying includes stepwise drying. Stepwise drying can suppress the migration and aggregation of active components on the carrier surface, further avoid grain growth, and contribute to improving the dispersion of active components.

[0025] According to some embodiments of the present invention, the drying includes stepwise drying at 35–55°C, 60–85°C, and 90–120°C in sequence.

[0026] In this invention, drying is carried out in stages at 35-55°C, 60-85°C, and 90-120°C. The material heating process is strictly controlled to prevent thermal migration caused by excessive heating. This allows the active components in the bulk phase to migrate rapidly to the carrier surface, forming particle aggregates and thus reducing the dispersion of the active ingredients.

[0027] According to some embodiments of the present invention, the drying time is 2 to 6 hours when drying at 35 to 55°C, and / or 2 to 6 hours when drying at 60 to 85°C, and / or 6 to 10 hours when drying at 90 to 120°C.

[0028] According to some embodiments of the present invention, the drying further includes air drying before step drying.

[0029] According to some embodiments of the present invention, the roasting temperature is 300-600°C, preferably 350-550°C; and the roasting time is 2-6 hours.

[0030] Thirdly, the present invention provides the application of the above-described catalyst or the catalyst prepared by the above-described preparation method in the synthesis of methane from syngas.

[0031] According to some embodiments of the present invention, the catalyst is pretreated by reduction before being applied to the synthesis gas to methane reaction.

[0032] According to some embodiments of the present invention, the temperature of the reduction pretreatment is 300-600°C, the time is 0.5-3h, and the reducing gas is an H2 / inert gas with an H2 content of 1-10v%.

[0033] According to some embodiments of the present invention, the temperature of the reduction pretreatment is 350-500°C and the time is 1-2 hours.

[0034] The beneficial effects of this invention are at least as follows:

[0035] The methanation catalyst provided by this invention features a simple preparation process with no waste liquid discharge, making it environmentally friendly and easy to operate. Furthermore, it utilizes inexpensive transition metals instead of expensive precious metals, reducing catalyst production costs. The catalyst preparation and reduction processes meet energy conservation and emission reduction requirements, giving it a competitive advantage in the market economy and facilitating industrial production. Simultaneously, the methanation catalyst provided by this invention exhibits advantages such as high CO conversion rate, high CH4 selectivity and yield, good low-temperature reactivity, and good stability, making it suitable for industrial production. Attached Figure Description

[0036] Figure 1 These are the H2-TPR spectra of the methanation catalysts of Examples 1, 10, 11 and Comparative Examples 2-3.

[0037] Figure 2 This is a graph showing the CO methanation reaction performance of the methanation catalyst in Example 1. Detailed Implementation

[0038] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for illustrating this patent and do not limit the scope of protection of this invention in any way.

[0039] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0040] Example 1

[0041] Weigh 15g of Y molecular sieve particles (40-60 mesh) and 14.870g (0.05113mol) of Ni(NO3)2·6H2O, 1.892g (0.00436mol) of Ce(NO3)3·6H2O, and 2.724g (0.00936mol) of Co(NO3)2·6H2O. Dissolve Ni(NO3)2·6H2O, Ce(NO3)3·6H2O, and Co(NO3)2·6H2O in water to prepare 15mL of mixed metal salt solution. Pour the solution into the Y molecular sieve support and impregnate it in ultrasound for 0.5h. After air drying, perform stepwise drying at 50℃ for 2h, 80℃ for 2h, and 100℃ for 8h. Finally, calcine at 450℃ for 4h to obtain the NiO-CeO2-Co3O4 / Y-1 catalyst.

[0042] Example 2

[0043] The NiO-CeO2-Co3O4 / Y catalyst was prepared according to the method in Example 1, except that the amount of Ce(NO3)3·6H2O was 0.765g (0.00176mol) and the amount of Co(NO3)2·6H2O was 4.352g (0.01495mol), and it was labeled as NiO-CeO2-Co3O4 / Y-2 catalyst.

[0044] Example 3

[0045] The NiO-CeO2-Co3O4 / Y catalyst was prepared according to the method in Example 1, except that the amount of Ce(NO3)3·6H2O was 1.523 g (0.00351 mol) and the amount of Co(NO3)2·6H2O was 3.262 g (0.01121 mol), and it was labeled as NiO-CeO2-Co3O4 / Y-3 catalyst.

[0046] Example 4

[0047] The NiO-CeO2-Co3O4 / Y catalyst was prepared according to the method in Example 1, except that the amount of Ce(NO3)3·6H2O was 2.282 g (0.00526 mol) and the amount of Co(NO3)2·6H2O was 2.182 g (0.00750 mol), and it was labeled as NiO-CeO2-Co3O4 / Y-4 catalyst.

[0048] Example 5

[0049] The NiO-CeO2-Co3O4 / Y catalyst was prepared according to the method in Example 1, except that the amount of Ce(NO3)3·6H2O was 3.042 g (0.00701 mol) and the amount of Co(NO3)2·6H2O was 1.092 g (0.00375 mol), and it was labeled as NiO-CeO2-Co3O4 / Y-5 catalyst.

[0050] Example 6

[0051] The NiO-CeO2-Co3O4 / Y catalyst was prepared according to the method in Example 1, except that the amount of Ni(NO3)2·6H2O was 7.435 g (0.02557 mol), the amount of Ce(NO3)3·6H2O was 3.782 g (0.00871 mol), and the amount of Co(NO3)2·6H2O was 5.440 g (0.01869 mol), and it was labeled as NiO-CeO2-Co3O4 / Y-6 catalyst.

[0052] Example 7

[0053] The NiO-CeO2-Co3O4 / Y catalyst was prepared according to the method in Example 1, except that the amount of Ni(NO3)2·6H2O was 3.722 g (0.01280 mol), the amount of Ce(NO3)3·6H2O was 4.732 g (0.01090 mol), and the amount of Co(NO3)2·6H2O was 6.803 g (0.02337 mol), and it was labeled as NiO-CeO2-Co3O4 / Y-7 catalyst.

[0054] Example 8

[0055] The NiO-CeO2-Co3O4 / Y catalyst was prepared according to the method in Example 1, except that the amount of Ni(NO3)2·6H2O was 10.406 g (0.03578 mol), the amount of Ce(NO3)3·6H2O was 0.378 g (0.00087 mol), and the amount of Co(NO3)2·6H2O was 8.159 g (0.02803 mol), and it was labeled as NiO-CeO2-Co3O4 / Y-8 catalyst.

[0056] Example 9

[0057] The NiO-CeO2-Co3O4 / Y catalyst was prepared according to the method in Example 1, except that the amount of Ni(NO3)2·6H2O was 10.406 g (0.03578 mol), the amount of Ce(NO3)3·6H2O was 5.675 g (0.01307 mol), and the amount of Co(NO3)2·6H2O was 0.544 g (0.00187 mol), and it was labeled as NiO-CeO2-Co3O4 / Y-9 catalyst.

[0058] Example 10

[0059] Weigh out 15g ZSM-5 molecular sieve particles (40-60 mesh) and 14.870 g (0.05113 mol) Ni(NO3)2·6H2O, 1.892 g (0.00436 mol) Ce(NO3)3·6H2O, and 2.724 g (0.00936 mol) Co(NO3)2·6H2O were used. Ni(NO3)2·6H2O, Ce(NO3)3·6H2O, and Co(NO3)2·6H2O were dissolved in water to prepare 15 mL of mixed metal salt solution. This solution was poured into the ZSM-5 molecular sieve support and impregnated with ultrasound for 0.5 h. After natural air drying, stepwise drying was performed at 50 °C for 2 h, 80 °C for 2 h, and 100 °C for 8 h. Finally, the solution was calcined at 450 °C for 4 h to obtain the NiO-CeO2-Co3O4 / ZSM-5 catalyst.

[0060] Example 11

[0061] Weigh out 15g 13X molecular sieve particles (40-60 mesh) and 14.870 g (0.05113 mol) Ni(NO3)2·6H2O, 1.892 g (0.00436 mol) Ce(NO3)3·6H2O, and 2.724 g (0.00936 mol) Co(NO3)2·6H2O were prepared by dissolving Ni(NO3)2·6H2O, Ce(NO3)3·6H2O, and Co(NO3)2·6H2O in water to prepare 15 mL mixed metal salt solutions. These solutions were then poured into a 13X molecular sieve support and impregnated with ultrasound for 0.5 h. After natural air drying, the solutions were subjected to stepwise drying at 50 °C for 2 h, 80 °C for 2 h, and 100 °C for 8 h, followed by calcination at 450 °C for 4 h to obtain the NiO-CeO2-Co3O4 / 13X catalyst.

[0062] Comparative Example 1

[0063] Weigh 14.870 g (0.05113 mol) Ni(NO3)2·6H2O, dissolve Ni(NO3)2·6H2O in water to prepare 15 mL of nickel nitrate solution, pour it into 15 g of Al2O3 support (40-60 mesh), impregnate in ultrasonication for 0.5 h, air dry naturally, and then perform stepwise drying: drying at 50 °C for 2 h, drying at 80 °C for 2 h, drying at 100 °C for 8 h, and calcining at 450 °C for 4 h to obtain NiO / Al2O3 catalyst.

[0064] Comparative Example 2

[0065] Weigh 14.870 g (0.05113 mol) Ni(NO3)2·6H2O, dissolve Ni(NO3)2·6H2O in water to prepare 15 mL of nickel nitrate solution, pour it into 15 g of Y molecular sieve support (40-60 mesh), impregnate in ultrasound for 0.5 h, air dry naturally, and then perform stepwise drying: drying at 50 °C for 2 h, drying at 80 °C for 2 h, drying at 100 °C for 8 h, and calcining at 450 °C for 4 h to obtain NiO / Y catalyst.

[0066] Comparative Example 3

[0067] Weigh 15g of Al2O3 particles (40-60 mesh), 14.870g (0.05113mol) of Ni(NO3)2·6H2O, 1.892g (0.00436mol) of Ce(NO3)3·6H2O, and 2.724g (0.00936mol) of Co(NO3)2·6H2O. Dissolve Ni(NO3)2·6H2O, Ce(NO3)3·6H2O, and Co(NO3)2·6H2O in water to prepare 15mL of mixed metal salt solution. Pour the solution into an Al2O3 support and impregnate it in ultrasound for 0.5h. After air drying, perform stepwise drying at 50℃ for 2h, 80℃ for 2h, and 100℃ for 8h. Finally, calcine at 450℃ for 4h to obtain the NiO-CeO2-Co3O4 / Al2O3 catalyst.

[0068] Comparative Example 4

[0069] Weigh 15g of Y molecular sieve particles (40-60 mesh), 14.870g (0.05113mol) of Ni(NO3)2·6H2O, and 1.892g (0.00436mol) of Ce(NO3)3·6H2O. Dissolve Ni(NO3)2·6H2O and Ce(NO3)3·6H2O separately in water to prepare 15mL of mixed metal salt solution. Pour the solution into the Y molecular sieve support and impregnate it in ultrasound for 0.5h. After air drying, perform stepwise drying at 50℃ for 2h, 80℃ for 2h, and 100℃ for 8h. Finally, calcine at 450℃ for 4h to obtain the NiO-CeO2 / Y catalyst.

[0070] Comparative Example 5

[0071] Weigh 15g of Y molecular sieve particles (40-60 mesh), 14.870g (0.05113mol) of Ni(NO3)2·6H2O, and 2.724g (0.00936mol) of Co(NO3)2·6H2O. Dissolve Ni(NO3)2·6H2O and Co(NO3)2·6H2O separately in water to prepare 15mL of mixed metal salt solution. Pour the solution into the Y molecular sieve support and impregnate it in ultrasound for 0.5h. After air drying, perform stepwise drying at 50℃ for 2h, 80℃ for 2h, and 100℃ for 8h. Finally, calcine at 450℃ for 4h to obtain the NiO-Co3O4 / Y catalyst.

[0072] Comparative Example 6

[0073] Weigh 15g of Y molecular sieve particles (40-60 mesh), 1.892g (0.00436mol) of Ce(NO3)3·6H2O and 2.724g (0.00936mol) of Co(NO3)2·6H2O. Dissolve Ce(NO3)3·6H2O and Co(NO3)2·6H2O in water to prepare 15mL of mixed metal salt solution. Pour the solution into the Y molecular sieve support and impregnate it in ultrasound for 0.5h. After air drying, perform stepwise drying at 50℃ for 2h, 80℃ for 2h, and 100℃ for 8h. Then calcine at 450℃ for 4h to obtain the CeO2-Co3O4 / Y catalyst.

[0074] Comparative Example 7

[0075] Weigh 15g of Y molecular sieve particles (40-60 mesh), 14.870g (0.05113mol) of Ni(NO3)2·6H2O, 4.772g (0.01861mol) of Mg(NO3)2·6H2O, and 2.724g (0.00936mol) of Co(NO3)2·6H2O. Dissolve Ni(NO3)2·6H2O, Mg(NO3)2·6H2O, and Co(NO3)2·6H2O in water to prepare 15mL of mixed metal salt solution. Pour the solution into an Al2O3 support and impregnate it in ultrasound for 0.5h. After air drying, perform stepwise drying at 50℃ for 2h, 80℃ for 2h, and 100℃ for 8h. Finally, calcine at 450℃ for 4h to obtain the NiO-MgO-Co3O4 / Y catalyst.

[0076] Characterization data of the catalysts in each embodiment and comparative example are detailed in Table 1.

[0077] Specific surface area and pore volume were obtained by BET testing; average pore size was obtained by XRD testing; elemental content was obtained by XRF testing; and the reduction performance of the catalyst was obtained by H2-TPR testing.

[0078] The H2-TPR spectra of the methanation catalysts of Examples 1, 10, 11 and Comparative Examples 2-3 are as follows: Figure 1 As shown in the figure, the α peak is attributed to the reduction of highly dispersed NiO on the surface, the β peak is attributed to the reduction of NiO that interacts with the additives, and the γ peak is attributed to the reduction of NiO in the bulk phase.

[0079] Table 1 Characterization data of the catalyst

[0080]

[0081]

[0082] Note: The contents of the active ingredients, first auxiliary agent and second auxiliary agent in Table 1 are all calculated as metal elements.

[0083] As can be seen from Table 1, by comparing Comparative Example 1 and Comparative Example 2, and by comparing Example 1 and Comparative Example 3, it can be concluded that the large specific surface area of ​​Y molecular sieve helps to improve the dispersion of Ni, reduce the grain size of active components, facilitate the reduction of NiO, lower the reduction temperature, and increase the content of Ni species of active components that are highly dispersed on the surface of the support.

[0084] Comparing Example 1, Comparative Example 4, and Comparative Example 5, it can be seen that the addition of CeO2 and Co3O4 promoters increases the specific surface area and pore volume of the catalyst, reduces the grain size, shifts the reduction peak towards lower temperatures, and eliminates the γ-peak reduction peak. This indicates that the addition of promoters helps reduce the number of difficult-to-reduce Ni species in the bulk phase, increases the number of highly dispersed Ni species on the surface, and lowers the reduction temperature of the catalyst, thereby helping to improve the reduction performance of the catalyst.

[0085] Comparing Example 1 with Comparative Example 2, it can be seen that the combined effect of CeO2 and Co3O4 enhances the interaction between the active component and the additives, significantly increases the highly dispersed Ni species on the surface, reduces the grain size of Ni species, and greatly reduces the number of Ni species in the bulk phase. Therefore, the reduction temperature of the catalyst is significantly reduced, and the reduction performance of the catalyst is significantly improved. In Example 1, the α reduction peak temperature is as low as 272℃, the β reduction peak temperature is as low as 388℃, and the γ reduction peak basically disappears.

[0086] Catalyst Reaction Activity Evaluation

[0087] A stainless steel tube fixed-bed reactor was used to evaluate the CO methanation activity of the catalysts from Examples 1, 7-11, and Comparative Examples 1-7. The activity test results for each catalyst are shown in Table 2. The activity test results for the catalyst of Example 1 are as follows: Figure 2 As shown.

[0088] Before use, the catalyst is pretreated by reduction: 100 mL / min of 10 v% H2 / N2 gas is introduced, and the temperature is increased to 450 °C at a rate of 10 °C / min under normal pressure. The reduction is carried out for 1 hour, and the reaction raw material gas is introduced after the temperature reaches the reaction temperature.

[0089] The process conditions for the CO methanation reaction are as follows: H2 / CO ratio in the feed gas is 3:1, gas flow rate is 100 mL / min, and gas hourly space velocity is 10000 h⁻¹. -1 The reaction temperature is 200℃ and the reaction pressure is atmospheric pressure.

[0090] Table 2 Results of CO methanation reaction activity evaluation

[0091]

[0092]

[0093] As shown in Table 2, compared with Al2O3 support, the catalyst using zeolite molecular sieve as support exhibits relatively higher CO conversion and CH4 selectivity, as well as better stability. This is attributed to the large specific surface area and pore volume of zeolite molecular sieve, which helps the active components to be highly dispersed on the support surface, reduces crystal size, prevents agglomeration, promotes the reduction of active components, lowers the reduction temperature, meets the requirements of energy saving and consumption reduction, and at the same time prevents the agglomeration and growth of active components caused by high-temperature reduction, thereby improving the stability of the catalyst.

[0094] Compared with NiO / Y catalysts, the addition of CeO2 and Co3O4 promoters leads to interactions between Ni species and promoters, which significantly shifts the catalyst reduction peak towards lower temperatures. It also greatly increases the number of highly dispersed Ni species on the surface, reduces the number of difficult-to-reduce Ni species in the bulk phase, lowers the temperature required for the reduction of the active components in the catalyst, and improves the catalyst activity and stability.

[0095] Depend on Figure 2 It can be seen that the catalyst in Example 1 significantly improves CO conversion and CH4 selectivity with increasing reaction temperature. When the reaction temperature is as low as 200℃, the CO conversion on the catalyst can reach 100%, the CH4 selectivity can reach 97%, and the CH4 yield can reach 97%. Moreover, there is no deactivation phenomenon after 50 hours of continuous reaction, which shows promising prospects for industrial application.

[0096] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. The application of a catalyst in the synthesis of methane from syngas, characterized in that, The catalyst comprises zeolite molecular sieve as support, NiO as active ingredient, CeO2 as first promoter and Co3O4 as second promoter.

2. The application according to claim 1, characterized in that, The mass ratio of the carrier, active component, first adjuvant, and second adjuvant is 1:(0.06~0.26):(0.01~0.15):(0.01~0.15).

3. The application according to claim 1 or 2, characterized in that, The zeolite molecular sieve is at least one of ZSM-5 molecular sieve, Y molecular sieve, and 13X molecular sieve.

4. The application according to claim 1 or 2, characterized in that, The method for preparing the catalyst includes: A mixed metal salt aqueous solution containing an active component precursor, a first auxiliary agent precursor, and a second auxiliary agent precursor was prepared; the support was impregnated with the mixed metal salt aqueous solution, dried, and calcined to obtain the catalyst.

5. The application according to claim 4, characterized in that, The impregnation is performed using an ultrasonic-assisted equal-volume impregnation method; And / or, the active component precursor is nickel nitrate and / or nickel acetate; And / or, the first auxiliary agent precursor is at least one of cerium nitrate, cerium sulfate, and cerium chloride; And / or, the second auxiliary agent precursor is at least one of cobalt nitrate, cobalt sulfate, and cobalt chloride.

6. The application according to claim 5, characterized in that, The active component precursor is nickel nitrate; And / or, the first auxiliary agent precursor is cerium nitrate; And / or, the second auxiliary agent precursor is cobalt nitrate.

7. The application according to claim 4, characterized in that, The molar ratio of the active component precursor, the first auxiliary agent precursor, and the second auxiliary agent precursor, based on the metal content, is 1:(0.02~0.90):(0.05~1.90).

8. The application according to claim 4, characterized in that, The drying process includes step-by-step drying.

9. The application according to claim 4, characterized in that, The drying process includes stepwise drying at 35~55℃, 60~85℃, and 90~120℃ in sequence. And / or, the drying process further includes: air drying prior to step drying.

10. The application according to claim 9, characterized in that, The drying time is 2-6 hours when drying at 35-55℃, and / or 2-6 hours when drying at 60-85℃, and / or 6-10 hours when drying at 90-120℃.

11. The application according to claim 4, characterized in that, The roasting temperature is 300~600℃; the roasting time is 2~6h.

12. The application according to claim 11, characterized in that, The roasting temperature is 350~550℃.

13. The application according to claim 1 or 2, characterized in that, The catalyst is pretreated by reduction before being used in the synthesis gas to methane reaction.

14. The application according to claim 13, characterized in that, The reduction pretreatment is performed at a temperature of 300-600℃ for 0.5-3 hours, and the reducing gas is an H2 / inert gas with an H2 content of 1-10v%.

15. The application according to claim 14, characterized in that, The reduction pretreatment is performed at a temperature of 350~500℃ for 1~2 hours.

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