Sulfur-resistant carbon dioxide methanation catalyst, preparation method and application

Abstract

The present invention discloses a sulfur-resistant carbon dioxide methanation catalyst, a preparation method, and an application thereof. The catalyst carrier comprises Al2O3 and ZrO2, a carrier modifier is nitrogen-doped mesoporous carbon and / or silicon carbide, an active component comprises NiO and MoO3, an auxiliary agent comprises CeO2 and MnO2, and a coating is a Co-Zn coating. The Al2O3 content is 10-70wt%, the ZrO2 content is 2-15wt%, the carrier modifier content is 1-75wt%, the active component content is 10-50wt%, and the auxiliary agent content is 1-5wt%. The catalyst of the present invention has high reaction efficiency, good stability, high selectivity, and good heat resistance. When used, different catalysts are loaded in layers, and the bed temperature rises slowly, the hot spot temperature is low, and the generation of local high-temperature zones is avoided, thereby avoiding sulfur poisoning and sintering deactivation of the catalyst, reducing investment and operating costs, extending the catalyst life, and improving the safety of device operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of methane catalysts, and in particular relates to a sulfur-resistant carbon dioxide methanation catalyst, a preparation method and an application thereof. Background Art

[0002] With the increasing depletion of non-renewable energy sources such as oil and coal, coupled with environmental degradation caused by rising atmospheric greenhouse gas concentrations, converting the greenhouse gas carbon dioxide into high-value-added chemical products has become a hot topic of research in both domestic and international academic circles. Among them, the synthesis of methane from carbon dioxide hydrogenation not only reduces atmospheric carbon dioxide concentrations but also serves as a fuel, alleviating energy issues to a certain extent. Furthermore, methane is a commonly used chemical raw material and can be further used to produce chemical products such as acetylene and synthetic ammonia. Therefore, the development of an efficient carbon dioxide methanation technology is of great practical significance.

[0003] CO2(g)+4H2(g)→CH4(g)+2H2 O(g)△Hθ298K=-165kJ / mol

[0004] △Gθ298K=-113kJ / mol

[0005] Among existing industrial methanation catalysts, supported Ni-based catalysts are the most effective. However, Ni-based catalysts are very sensitive to surface carbon deposition and sulfur species, leading to catalyst deactivation and poisoning. When using Ni-based catalysts, acidic gases such as H2S, which are heavily contained in the feed gas, must be removed to reduce their content to less than 0.1 ppm. Carbon dioxide gas from typical industrial sources contains sulfur, necessitating costly desulfurization and purification prior to methanation.

[0006] Currently, most sulfur-tolerant methanation catalysts are supported catalysts, using Mo, W, Ni, and Co as active components, Al2O3, CeO2, ZrO2, SiO2, and TiO2 as supports, and K, La, Cr, and Fe as promoters. However, their methanation catalytic activity is low, with CO conversion rates typically ranging from 50% to 90%, and CH4 selectivity of only 60% to 70%. Their activation temperatures are also relatively high, typically above 450°C. Furthermore, most catalysts have not undergone catalyst lifespan testing or have short lifespans. In particular, most catalysts are not resistant to high temperatures, which significantly limits the progress of sulfur-tolerant methanation processes. Furthermore, at high CO2 levels in the feed gas, CO conversion rates drop to 20% to 50%, and CH4 selectivity is only 30% to 50%. Reports on sulfur-tolerant carbon dioxide methanation catalysts are relatively limited. Patent CN103551053A discloses a copper-based carbon dioxide methanation catalyst and its preparation method, but the patent does not mention sulfur tolerance. Patent CN 112642440 B discloses a sulfur-resistant carbon dioxide methanation catalyst, but the catalyst uses the noble metal Rh as an active component and has a high manufacturing cost.

[0007] From a thermodynamic perspective, lowering the methanation operating temperature favors a positive reaction equilibrium. Theoretical calculations show that when the inlet CO+CO2 content is below 20%, the CO / CO2 equilibrium conversion rate is ≥99% within an operating temperature range of ≤320°C and an operating pressure range of 2.5-4.5 MPa. Therefore, by employing an effective temperature-controlled reactor to maintain the bed outlet temperature below 320°C, efficient CO / CO2 conversion can be achieved with a single reactor, reducing both equipment investment and operating energy consumption.

[0008] Patent CN110237778A discloses an isothermal reactor and a process method for convenient catalyst replacement. Its characteristics are that the reactor adopts a concentric circle design, the catalyst is loaded in an annular screen, the screen is loaded into the concentric circle reactor as a whole, and the catalyst is disassembled and assembled as a whole. The focus is on the structural characteristics of the reactor.

[0009] Patent CN113289663A discloses a method for preparing a methanation catalyst for an isothermal fixed bed, in which a mesoporous support is prepared using silicon nitride and aluminum oxide.

[0010] Patent CN204247177U discloses an adiabatic-isothermal methanation reactor, in which an adiabatic section and an isothermal section are arranged, and the isothermal section is a shell-and-tube structure.

[0011] In previous public patents, the starting point for developing catalysts was to improve the activity of the catalyst. However, research has shown that the intrinsic rate of the CO2 methanation reaction is very fast. In industrial adiabatic fixed-bed reactors, hot spots appear at 1 / 5 to 1 / 8 of the bed position. The catalyst bed temperature drops behind the hot spots, making it easy for local high-temperature areas to appear in the methanation catalyst bed, and the catalyst is easily sintered. At the same time, the reaction performance of the catalyst on the rear side is not reflected.

[0012] In actual operation, improper temperature control within the methanation reactor can easily lead to excessive bed temperatures, burn-through of reactor components, and deactivation of the catalyst due to high-temperature sintering. Therefore, to ensure stable operation within the methanation reactor, effectively remove the generated heat, and achieve uniform bed temperature control, it is necessary to study the use and loading methods of methanation catalysts from a kinetic perspective. Summary of the Invention

[0013] The purpose of the present invention is to solve the above technical problems and provide a sulfur-resistant carbon dioxide methanation catalyst with high efficiency, good stability, high selectivity and good heat resistance, as well as a preparation method and application.

[0014] To achieve the above-mentioned object, the present invention provides a sulfur-resistant carbon dioxide methanation catalyst, characterized in that: the catalyst includes a carrier, a carrier modifier, an active component, an auxiliary agent and a coating; the carrier includes Al2O3 and ZrO2, the carrier modifier is nitrogen-doped mesoporous carbon and / or silicon carbide, the active component includes NiO and MoO3, the auxiliary agent includes CeO2 and MnO2, and the coating is a Co-Zn coating; based on the total weight percentage of the catalyst: the content of Al2O3 is 10-70wt%, the content of ZrO2 is 2-15wt%, the content of the carrier modifier is 1-75wt%, the content of the active component is 10-50wt%, and the mass ratio of NiO:MoO3 is 1-5:0-1, the content of the auxiliary agent is 1-5wt%, and the mass ratio of CeO2:MnO2 is 1-5:1, the content of the Co-Zn coating is 0-10wt%, and the mass ratio of CoO:ZnO is 1:1-3.

[0015] Furthermore, when the support modifier is a mixture of nitrogen-doped mesoporous carbon and silicon carbide, the mass ratio of nitrogen-doped mesoporous carbon to silicon carbide is 1-3:1-3.

[0016] Furthermore, the nitrogen-doped mesoporous carbon has a nitrogen content of 1.5-12% and a specific surface area of ​​800-1200 m 2 / g, and the average pore diameter is 4 to 8.1 nm.

[0017] A method for preparing the catalyst as described above is also provided as follows:

[0018] 1) stirring and ultrasonically dispersing the support modifier in a salt solution to form a suspension, and heating the suspension to 50-80° C. and keeping it warm for later use; dissolving a precursor salt in deionized water to form a precursor salt solution, heating the precursor salt solution and the precipitant solution to 50-80° C. respectively, and adding the precursor salt solution and the precipitant solution dropwise to the suspension in parallel to perform a precipitation reaction, maintaining the solution at a pH of 7-8 and continuously stirring;

[0019] 2) Adding cobalt and zinc salt solutions to the solution, adding alkaline precipitant, maintaining the solution pH at 7-8, and continuing stirring;

[0020] 3) After precipitation, the catalyst is aged, washed, filtered, dried, calcined, and then formed into tablets to obtain the desired catalyst.

[0021] Furthermore, in step 1), the molar ratio of the precursor salt to the precipitant is 0.1 to 10:1, the mass concentration of the precursor salt solution is 0.5 to 5%; and the solid-liquid mass ratio of the suspension is 1:20 to 1:50.

[0022] Furthermore, the precursor salt is composed of nickel nitrate, manganese nitrate, cerium nitrate, aluminum nitrate, zirconium nitrate and ammonium molybdate; the Co salt is cobalt nitrate, and the Zn salt is zinc nitrate; and the precipitant is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate.

[0023] Furthermore, in the step 3), the calcination temperature is 300-600° C., the calcination time is 4-12 hours, and the calcination atmosphere is nitrogen.

[0024] Finally, an application of the catalyst as described above is provided, wherein a catalyst active layer is loaded in a reactor, and an inert filler layer is arranged at both ends of the catalyst active layer, wherein the catalyst active layer is composed of a WH-HS catalyst and / or a WH-LS catalyst and / or a WH-HM catalyst;

[0025] The WH-HS catalyst is a highly sulfur-resistant methanation catalyst: the content of Al2O3 is 10-30wt%, the content of ZrO2 is 2-5wt%; the content of the support modifier is 40-70wt%, the mass ratio of nitrogen-doped mesoporous carbon: silicon carbide is 1-3:1-3; the content of the active component is 10-30wt%, the mass ratio of NiO:MoO3 is 1-3:1; the content of the auxiliary agent is 1-5wt%, the mass ratio of CeO2:MnO2 is 1-5:1; the content of the Co-Zn coating is 5-10wt%, and the mass ratio of CoO:ZnO is 1:1-3;

[0026] The WH-LS catalyst is a low-sulfur-tolerant methanation catalyst: the content of Al2O3 is 20-50wt%, the content of ZrO2 is 2-10wt%, the content of the support modifier is 15-30wt%, the mass ratio of nitrogen-doped mesoporous carbon: silicon carbide is 1-3:1-3; the content of the active component is 20-40wt%, the mass ratio of NiO:MoO3 is 5-10:1; the content of the auxiliary agent is 1-5wt%, the mass ratio of CeO2:MnO2 is 1-5:1; the content of the Co-Zn coating is 1-5wt%, and the mass ratio of CoO:ZnO is 1:1-3;

[0027] The WH-HM catalyst is a highly active methanation catalyst: the Al2O3 content is 40-60wt%, the ZrO2 content is 2-10wt%, the support modifier content is 1-10wt%, the mass ratio of nitrogen-doped mesoporous carbon: silicon carbide is 1-3:1-3, the active component NiO content is 25-50wt%, the auxiliary agent content is 1-5wt%, and the mass ratio of CeO2:MnO2 is 1-5:1.

[0028] Furthermore, the catalyst active layers comprise 3 to 6 layers, all arranged along the airflow direction. The first layer comprises a WH-HS catalyst, the second comprises a WH-LS catalyst, and the remaining layers comprise a mixture of WH-HM and WH-LS catalysts. The mass ratio of the WH-HM to WH-LS catalysts is 3:0.1 to 1, and the mass ratio of the WH-HM catalyst increases layer by layer along the airflow direction. The catalysts in the catalyst active layers of the same layer have the same shape. The reactor is a shell-and-tube temperature-controlled reactor, with the catalyst loaded in the shell layer and water supplying and removing heat through the tube layer.

[0029] Furthermore, in the reactor: the bed temperature is 240-290°C, the hot spot temperature is 380-500°C, and the outflow temperature of the reactor gas outlet is 250-300°C.

[0030] By using metal nitrates as catalysts, the microporous activated carbon is expanded into mesoporous carbon, and nitrogen-doped carbon is modified using melamine and urea as nitrogen sources. Mesoporous carbon has a well-developed mesoporous structure, which facilitates the molecular diffusion of reactants and products and the transfer of reaction heat. Nitrogen doping in the mesoporous carbon promotes electron transfer and enhances the reduction ability of the catalyst. Nitrogen doping also facilitates the loading and dispersion of nickel, promoting its reduction and improving the low-temperature activity and high-temperature stability of the catalyst.

[0031] The catalyst of the present invention uses ZrO2-Al2O3 and nitrogen-doped mesoporous carbon or SiC as a composite carrier. The addition of ZrO2 improves the electron transfer ability and acidity of the Al2O3 carrier. The surface of the nitrogen-doped material can adsorb a large amount of hydrogen, which is transferred to the active sites on the catalyst surface, thereby increasing the rate of the hydrogenation reaction. This is beneficial for improving the activity of the catalyst in the low-temperature methanation reaction of CO2. It also has excellent thermal conductivity and electron transfer properties, while improving the low-temperature activity and high-temperature resistance of the catalyst. The hydrophobicity of the nitrogen-doped mesoporous carbon material is beneficial for desorption of water produced after carbon dioxide methanation, thereby improving the carbon dioxide methanation performance at low temperatures. The introduction of the nitrogen-doped mesoporous carbon interacts with the Ni active component, promoting the effective dispersion of the active component Ni of the formed catalyst. The calcined Ni grains are small, the reaction activation temperature is low, and it has good low-temperature reaction activity. It is particularly suitable for methanation heat transfer reactors and can effectively reduce reactor equipment investment and operating costs. At the same time, after the nitrogen-doped mesoporous carbon is introduced into the catalyst, carbon sites are formed on the catalyst surface. The mesopores are beneficial for heat and mass transfer, and the nitrogen doping promotes the electron mobility of the surface. The carbon sites formed inhibit the generation and further expansion of carbon deposits, thereby improving the catalyst's resistance to carbon deposits. The in-situ introduction of SiC into the catalyst further enhances the catalyst's thermal conductivity. The introduction of Ce, Mn, and Mo additives further enhances the catalyst's activity and stability; the introduction of Mo enhances the catalyst's ability to adsorb sulfur, with sulfur preferentially adsorbed on Mo, thereby protecting the Ni-based active centers. In the catalyst preparation process, the present invention creatively introduces a Co-Zn coating by staged precipitation. The Co-Zn composite coating exhibits a strong adsorption capacity for sulfides, thereby enhancing the catalyst's sulfur resistance and protecting the catalyst's Ni active centers.

[0032] The introduction of Mo and Co-Zn has a certain impact on the catalyst's activity. Combined with temperature-controlled methanation technology, the catalyst active layer consists of a mixture of a high-sulfur-tolerant WH-HS catalyst, a low-sulfur-tolerant WH-LS catalyst, and a mixture of WH-LS and a high-activity WH-HM catalyst. The WH-HM catalyst's main active component is a composite oxide of nickel oxide, manganese oxide, cerium oxide, and molybdenum oxide. Nickel oxide and cerium oxide are used because the composite rare earth additives enhance interaction with nickel species, forming NiO species that promote active CO2 molecules at low temperatures. Mo and Co-Zn coatings enhance the adsorption of sulfides. The catalyst also contains nitrogen-doped mesoporous carbon or SiC, further improving its thermal conductivity and preventing heat accumulation. The WH-LS catalyst contains lower levels of the sulfur-tolerant components Mo and Co-Zn than the WH-HS catalyst, resulting in higher methanation performance. The WH-HM catalyst contains no sulfur-tolerant components, resulting in higher catalytic activity. Here, the three catalysts are mixed to achieve the purpose of reasonably controlling the reaction temperature of the catalyst bed, avoiding the influence of hydrogen sulfide in the catalyst, avoiding the generation of temperature runaway or local hot spots, extending the service life of the catalyst, and thus exerting a synergistic catalytic effect.

[0033] In addition, in the present invention, 3 to 6 layers of catalyst active layers are sequentially arranged along the direction of airflow. In addition to arranging multiple layers of catalyst active layers, the mixing ratio of the two catalysts in each layer is also limited. Based on the kinetic perspective, the catalyst hotspot temperature is closely related to the intrinsic activity of the catalyst. For this reason, the amount of WH-HM catalyst with high methanation reaction activity is increased layer by layer along the airflow direction, while the amount of WH-LS catalyst with high thermal conductivity and suitable methanation activity and sulfur resistance is gradually reduced. This can effectively lengthen the distance between the zero-meter temperature and the hotspot temperature, ensure that the bed temperature rises relatively slowly, and allow the hotspot temperature to appear in the second, third, or even later catalyst active layers without significant displacement, thereby achieving the purpose of lowering the bed hotspot temperature. This can not only improve the catalyst's single-pass conversion rate, but also avoid catalyst sintering and deactivation, thereby extending the service life. The catalysts in the same catalyst active layer have the same shape, so that the catalysts in each bed are evenly mixed, and are conducive to segmented loading, achieving the purpose of facilitating industrial loading and use.

[0034] The sensitive characteristics can make the methanation catalyst resistant to about 5ppm of sulfur while having stable methanation performance and good methanation effect; the filling method of the present invention can effectively reduce the hot spot temperature of the bed, reduce the concentration gradient of the catalyst axially, slow down the intensity of the methanation reaction, achieve gentle temperature rise in the bed, effectively avoid the risk of local high-temperature areas and catalyst sintering deactivation, and extend the service life of the catalyst and reactor; the filling structure of the present invention does not need to change the reactor structure, can withstand a certain amount of H2S, thereby reducing purification investment and operating costs, when the CO2 content of the reaction gas inlet is within 20%, a single reactor can be used to achieve efficient CO2 conversion, the bed temperature rise is small, the safety is high, there is no need to introduce circulating gas or steam dilution, energy saving and consumption reduction, and also effectively reducing equipment investment and operating costs.

[0035] Compared with the prior art, the present invention has the following beneficial effects: the sulfur-resistant carbon dioxide methanation catalyst of the present invention has high reaction efficiency, good stability, high selectivity and good heat resistance; different catalysts are loaded in layers during use, the bed temperature rises slowly and the hot spot temperature is low, thus avoiding the generation of local high-temperature zones, avoiding sulfur poisoning and sintering deactivation of the catalyst, reducing investment and operating costs, extending the catalyst life, and improving the safety of device operation. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to specific embodiments.

[0037] Example 1

[0038] WH-HS catalyst: 25 g nitrogen-doped mesoporous carbon (size > 500 mesh, 1100 m 2 / g, average pore size 5.5nm, nitrogen content 5%, of which pyridinic nitrogen 44.51%, pyrrolic nitrogen 26.59%, graphitic nitrogen 20.52%, oxidized nitrogen 8.38%) and 25g SiC (size> 500 mesh) were dispersed at high speed in a sodium nitrate solution (the mass concentration of the sodium nitrate solution was 5%, the ultrasonic frequency was controlled to be 40kHz, and the power was 800kW) to form a suspension (the solid-liquid mass ratio of the suspension was 1:20); then the suspension was heated to 50°C, 58.2g nickel nitrate, 95.6g aluminum nitrate, 6.9g zirconium nitrate, 4.1g manganese nitrate, 7.6g cerium nitrate, and 12.3g ammonium molybdate were prepared into a precursor salt solution, and sodium carbonate was prepared as a precipitant solution (take The precursor salt is prepared in a molar ratio of 0.1:1 to sodium carbonate, preheated to 80°C by electric heating, and then added dropwise to the suspension in parallel (the addition is completed within 50 minutes, and the stirring speed is 600 rpm), and a precipitation reaction is started. The pH of the solution is maintained at 7-8 and stirring is continued for 1 hour. A cobalt and zinc salt solution containing 5.8g of cobalt nitrate and 16.7g of zinc nitrate is added to the above solution, and an alkaline precipitant is added to maintain the pH of the solution at 7-8. Stirring is continued for 1-2 hours. The precipitate is subjected to multiple cycles of filter pressing, pulping, and washing until the conductivity of the filtrate reaches 50μS / cm, and then dried, and then calcined to obtain a catalyst powder. The calcination temperature is 300°C, the calcination time is 12 hours, and the calcination atmosphere is nitrogen.

[0039] Calculated by the mass of oxides, nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide account for 15%, 10%, 13%, 2%, 1%, 3%, 1.5% and 4.5% of the catalyst mass, respectively, and nitrogen-doped mesoporous carbon and SiC account for 25% of the catalyst mass, respectively.

[0040] WH-LS catalyst: The preparation method is the same as that of WH-HS catalyst, the difference lies in the different amounts of Mo, Co and Zn added.

[0041] The catalyst powder, calculated by the mass of oxides, is composed of nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide, which account for 25%, 5%, 40%, 4%, 1%, 3%, 0.5% and 1.5% of the catalyst mass respectively, and nitrogen-doped mesoporous carbon and SiC each account for 10% of the catalyst mass.

[0042] WH-HM catalyst: The preparation method is the same as that of WH-HS catalyst, but it does not contain Mo, Co, or Zn.

[0043] The catalyst powder, calculated by the mass of oxides, comprises nickel oxide, aluminum oxide, zirconium oxide, manganese oxide and cerium oxide, which account for 35%, 50%, 5%, 1% and 4% of the catalyst mass respectively; nitrogen-doped mesoporous carbon accounts for 2% of the catalyst mass; and SiC accounts for 3%.

[0044] Catalyst Performance Testing: The catalyst was reduced at 500°C for 10 hours and then evaluated for CO2 methanation performance. The reaction temperature was 250°C, the pressure was 2.5 MPa, and the feed gas composition was 20% CO, 80% H2, with an H2S content of 20 ppm. The results are shown in Table 1.

[0045] The reactor filling structure is: 2 layers of inert filler layers (M layer and N layer) and 6 layers of catalyst active layers (from top to bottom are A layer, B layer, C layer, D layer, E layer, and F layer). The first layer, A, is filled with WH-HS catalyst, which is in the shape of a four-hole wheel and has an outer diameter of 6 mm. The second layer, B, is filled with WH-LS catalyst, which is cylindrical and has an outer diameter of 3 mm. The third layer, C, has a loading ratio of 3:1 for WH-HM and WH-LS catalysts, both of which are spherical and have an outer diameter of 4 mm. The fourth layer, D, has a loading ratio of 5:1 for WH-HM and WH-LS catalysts, and the fifth layer, E, has a loading ratio of 6:1 for WH-HM and WH-LS catalysts, both of which are cylindrical and have an outer diameter of 3 mm. The sixth layer, F, has a loading ratio of 12:1 for WH-HM and WH-LS catalysts, both of which are spherical and have an outer diameter of 3 mm. Catalyst loading performance test:

[0046] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, it is preheated to 250℃ and enters the catalyst active layer, the hot spot temperature appears in the third layer (C layer) with a temperature of 385℃, and the gas temperature after passing through the F layer is 280℃, the CO2 conversion rate is ≥99.5%, the CH4 selectivity is ≥99.5%, and it runs continuously for 1000h. The hot spot position has not moved significantly and the catalyst activity remains unchanged.

[0047] Example 2

[0048] WH-HS catalyst: 25 g nitrogen-doped mesoporous carbon (size > 500 mesh, 1100 m 2 / g, average pore size 5.5nm, nitrogen content 5%, of which pyridinic nitrogen 44.51%, pyrrolic nitrogen 26.59%, graphitic nitrogen 20.52%, oxidized nitrogen 8.38%) and 25g SiC (size> 500 mesh) were dispersed at high speed in a sodium nitrate solution (the mass concentration of the sodium nitrate solution was 5%, the ultrasonic frequency was controlled to be 40kHz, and the power was 800kW) to form a suspension (the solid-liquid mass ratio of the suspension was 1:20); then the suspension was heated to 50°C, 58.2g nickel nitrate, 95.6g aluminum nitrate, 6.9g zirconium nitrate, 4.1g manganese nitrate, 7.6g cerium nitrate, and 12.3g ammonium molybdate were prepared into a precursor salt solution, and sodium carbonate was prepared as a precipitant solution (take The precursor salt is prepared at a molar ratio of 0.1:1 to sodium carbonate, preheated to 80°C by electric heating, and then added dropwise to the suspension in parallel (the addition is completed within 50 minutes, and the stirring speed is 600 rpm), a precipitation reaction is started, the pH of the solution is maintained at 7-8, and stirring is continued for 1 hour; a cobalt and zinc salt solution containing 5.8g of cobalt nitrate and 16.7g of zinc nitrate is added to the above solution, an alkaline precipitant is added, the pH of the solution is maintained at 7-8, and stirring is continued for 1-2 hours; the precipitate is subjected to multiple cycles of filter pressing, pulping, and washing until the conductivity of the filtrate is 50μS / cm, and then dried, and then calcined to obtain a catalyst powder; the calcination temperature is 400°C, the calcination time is 10 hours, and the calcination atmosphere is nitrogen.

[0049] Calculated by the mass of oxides, nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide account for 15%, 10%, 13%, 2%, 1%, 3%, 1.5% and 4.5% of the catalyst mass, respectively, and nitrogen-doped mesoporous carbon and SiC account for 25% of the catalyst mass, respectively.

[0050] WH-LS catalyst: The preparation method is the same as that of WH-HS catalyst, the difference lies in the different amounts of Mo, Co and Zn added.

[0051] The catalyst powder, calculated by the mass of oxides, is composed of nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide, which account for 25%, 5%, 40%, 4%, 1%, 3%, 0.5% and 1.5% of the catalyst mass respectively, and nitrogen-doped mesoporous carbon and SiC each account for 10% of the catalyst mass.

[0052] WH-HM catalyst: The preparation method is the same as that of WH-HS catalyst, but it does not contain Mo, Co, or Zn.

[0053] The catalyst powder, calculated by the mass of oxides, comprises nickel oxide, aluminum oxide, zirconium oxide, manganese oxide and cerium oxide, which account for 35%, 50%, 5%, 1% and 4% of the catalyst mass respectively; nitrogen-doped mesoporous carbon accounts for 2% of the catalyst mass; and SiC accounts for 3%.

[0054] Catalyst Performance Testing: The catalyst was reduced at 500°C for 10 hours and then evaluated for CO2 methanation performance. The reaction temperature was 250°C, the pressure was 2.5 MPa, and the feed gas composition was 20% CO, 80% H2, and 20 ppm H2S.

[0055] The reactor is packed with two layers of inert filler (M and N) and four layers of catalyst active layers (A, B, C, and D, from top to bottom). The first layer, Layer A, is filled with a four-hole, wheel-shaped WH-HS catalyst with an outer diameter of 6 mm. The second layer, Layer B, is filled with a cylindrical WH-LS catalyst with an outer diameter of 3 mm. The third layer, Layer C, has a 3:1 loading ratio of WH-HM to WH-LS catalysts, both of which are spherical and have an outer diameter of 4 mm. The fourth layer, Layer D, has a 6:1 loading ratio of WH-HM to WH-LS catalysts, both of which are cylindrical and have an outer diameter of 3 mm.

[0056] Catalyst loading performance test:

[0057] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, it is preheated to 250℃ and enters the catalyst active layer, the hot spot temperature appears in the third layer (C layer) at 400℃, and the gas temperature after passing through the D layer is 290℃, the CO2 conversion rate is ≥99.5%, the CH4 selectivity is ≥99.5%, and it runs continuously for 1000h. The hot spot position has not moved significantly and the catalyst activity remains unchanged.

[0058] Example 3

[0059] WH-HS catalyst: 25 g nitrogen-doped mesoporous carbon (size > 500 mesh, 1100 m 2 / g, average pore size 5.5nm, nitrogen content 5%, of which pyridinic nitrogen 44.51%, pyrrolic nitrogen 26.59%, graphitic nitrogen 20.52%, oxidized nitrogen 8.38%) and 25g SiC (size> 500 mesh) were dispersed at high speed in a sodium nitrate solution (the mass concentration of the sodium nitrate solution was 5%, the ultrasonic frequency was controlled to be 40kHz, and the power was 800kW) to form a suspension (the solid-liquid mass ratio of the suspension was 1:20); then the suspension was heated to 50°C, 58.2g nickel nitrate, 95.6g aluminum nitrate, 6.9g zirconium nitrate, 4.1g manganese nitrate, 7.6g cerium nitrate, and 12.3g ammonium molybdate were prepared into a precursor salt solution, and sodium carbonate was prepared as a precipitant solution (take The precursor salt is prepared at a molar ratio of 0.1:1 to sodium carbonate, preheated to 80°C by electric heating, and then added dropwise to the suspension in parallel (the addition is completed within 50 minutes, and the stirring speed is 600 rpm), a precipitation reaction is started, the pH of the solution is maintained at 7-8, and stirring is continued for 1 hour; a cobalt and zinc salt solution containing 5.8g of cobalt nitrate and 16.7g of zinc nitrate is added to the above solution, an alkaline precipitant is added, the pH of the solution is maintained at 7-8, and stirring is continued for 1-2 hours; the precipitate is subjected to multiple cycles of filter pressing, pulping, and washing until the conductivity of the filtrate is 50μS / cm, and then dried, and then calcined to obtain a catalyst powder; the calcination temperature is 500°C, the calcination time is 8 hours, and the calcination atmosphere is nitrogen.

[0060] Calculated by the mass of oxides, nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide account for 15%, 10%, 13%, 2%, 1%, 3%, 1.5% and 4.5% of the catalyst mass, respectively, and nitrogen-doped mesoporous carbon and SiC account for 25% of the catalyst mass, respectively.

[0061] WH-LS catalyst: The preparation method is the same as that of WH-HS catalyst, the difference lies in the different amounts of Mo, Co and Zn added.

[0062] The catalyst powder, calculated by the mass of oxides, is composed of nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide, which account for 25%, 5%, 40%, 4%, 1%, 3%, 0.5% and 1.5% of the catalyst mass respectively, and nitrogen-doped mesoporous carbon and SiC each account for 10% of the catalyst mass.

[0063] WH-HM catalyst: The preparation method is the same as that of WH-HS catalyst, but it does not contain Mo, Co, or Zn.

[0064] The catalyst powder, calculated by the mass of oxides, comprises nickel oxide, aluminum oxide, zirconium oxide, manganese oxide and cerium oxide, which account for 35%, 50%, 5%, 1% and 4% of the catalyst mass respectively; nitrogen-doped mesoporous carbon accounts for 2% of the catalyst mass; and SiC accounts for 3%.

[0065] Catalyst Performance Testing: The catalyst was reduced at 500°C for 10 hours and then evaluated for CO2 methanation performance. The reaction temperature was 250°C, the pressure was 2.5 MPa, and the feed gas composition was 20% CO, 80% H2, and 20 ppm H2S.

[0066] The reactor is packed with two layers of inert packing (M and N) and five layers of active catalysts (A, B, C, D, and E, from top to bottom). The first layer, Layer A, is filled with WH-HS catalyst in a four-hole cartwheel shape with an outer diameter of 6 mm. The second layer, Layer B, is filled with WH-LS catalyst in a cylindrical shape with an outer diameter of 3 mm. The third layer, Layer C, is filled with WH-HM and WH-LS catalysts in a 3:1 ratio, both spherical in shape with an outer diameter of 4 mm. The fourth layer, Layer D, is filled with WH-HM and WH-LS catalysts in a 5:1 ratio, both cylindrical in shape with an outer diameter of 3 mm. The fifth layer, Layer E, is filled with WH-HM and WH-LS catalysts in a 6:1 ratio, both spherical in shape with an outer diameter of 3 mm.

[0067] Catalyst loading performance test:

[0068] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, it is preheated to 250℃ and enters the catalyst active layer, the hot spot temperature appears in the third layer (C layer) at a temperature of 395℃, and the gas temperature after passing through the E layer is 288℃, the CO2 conversion rate is ≥99.5%, the CH4 selectivity is ≥99.5%, and it runs continuously for 1000h. The hot spot position has not moved significantly and the catalyst activity remains unchanged.

[0069] Example 4

[0070] WH-HS catalyst: 25 g nitrogen-doped mesoporous carbon (size > 500 mesh, 1100 m 2 / g, average pore size 5.5nm, nitrogen content 5%, of which pyridinic nitrogen 44.51%, pyrrolic nitrogen 26.59%, graphitic nitrogen 20.52%, oxidized nitrogen 8.38%) and 25g SiC (size> 500 mesh) were dispersed at high speed in a sodium nitrate solution (the mass concentration of the sodium nitrate solution was 5%, the ultrasonic frequency was controlled to be 40kHz, and the power was 800kW) to form a suspension (the solid-liquid mass ratio of the suspension was 1:20); then the suspension was heated to 50°C, 58.2g nickel nitrate, 95.6g aluminum nitrate, 6.9g zirconium nitrate, 4.1g manganese nitrate, 7.6g cerium nitrate, and 12.3g ammonium molybdate were prepared into a precursor salt solution, and sodium carbonate was prepared as a precipitant solution (take The precursor salt is prepared at a molar ratio of 0.1:1 to sodium carbonate, preheated to 80°C by electric heating, and then added dropwise to the suspension in parallel (the addition is completed within 50 minutes, and the stirring speed is 600 rpm), a precipitation reaction is started, the pH of the solution is maintained at 7-8, and stirring is continued for 1 hour; a cobalt and zinc salt solution containing 5.8g of cobalt nitrate and 16.7g of zinc nitrate is added to the above solution, an alkaline precipitant is added, the pH of the solution is maintained at 7-8, and stirring is continued for 1-2 hours; the precipitate is subjected to multiple cycles of filter pressing, pulping, and washing until the conductivity of the filtrate is 50μS / cm, and then dried, and then calcined to obtain a catalyst powder; the calcination temperature is 500°C, the calcination time is 8 hours, and the calcination atmosphere is nitrogen.

[0071] Calculated by the mass of oxides, nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide account for 15%, 10%, 13%, 2%, 1%, 3%, 1.5% and 4.5% of the catalyst mass, respectively, and nitrogen-doped mesoporous carbon and SiC account for 25% of the catalyst mass, respectively.

[0072] WH-LS catalyst: The preparation method is the same as that of WH-HS catalyst, the difference lies in the different amounts of Mo, Co and Zn added.

[0073] The catalyst powder, calculated by the mass of oxides, is composed of nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide, which account for 25%, 5%, 40%, 4%, 1%, 3%, 0.5% and 1.5% of the catalyst mass respectively, and nitrogen-doped mesoporous carbon and SiC each account for 10% of the catalyst mass.

[0074] WH-HM catalyst: The preparation method is the same as that of WH-HS catalyst, but it does not contain Mo, Co, or Zn.

[0075] The catalyst powder, calculated by the mass of oxides, comprises nickel oxide, aluminum oxide, zirconium oxide, manganese oxide and cerium oxide, which account for 35%, 50%, 5%, 1% and 4% of the catalyst mass respectively; nitrogen-doped mesoporous carbon accounts for 2% of the catalyst mass; and SiC accounts for 3%.

[0076] Catalyst Performance Testing: The catalyst was reduced at 500°C for 10 hours and then evaluated for CO2 methanation performance. The reaction temperature was 250°C, the pressure was 2.5 MPa, and the feed gas composition was 20% CO, 80% H2, and 20 ppm H2S.

[0077] The reactor is packed with two layers of inert filler (M and N) and three layers of active catalyst (A, B, and C, from top to bottom). The first layer, A, is filled with a four-hole, wheel-shaped WH-HS catalyst with an outer diameter of 6 mm. The second layer, B, is filled with a cylindrical WH-LS catalyst with an outer diameter of 3 mm. The third layer, C, contains a 3:1 ratio of WH-HM to WH-LS catalysts, both spherical in shape and with an outer diameter of 4 mm.

[0078] Catalyst loading performance test:

[0079] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, it is preheated to 250℃ and enters the catalyst active layer, the hot spot temperature appears in the second layer (B layer) at 410℃, and the gas temperature after passing through the C layer is 300℃, the CO2 conversion rate is ≥99.5%, the CH4 selectivity is ≥99.5%, and it runs continuously for 1000h. The hot spot position has not moved significantly and the catalyst activity remains unchanged.

[0080] Example 5

[0081] WH-HS catalyst: 25 g nitrogen-doped mesoporous carbon (size > 500 mesh, 1100 m 2 / g, average pore size 5.5nm, nitrogen content 5%, of which pyridinic nitrogen 44.51%, pyrrolic nitrogen 26.59%, graphitic nitrogen 20.52%, oxidized nitrogen 8.38%) and 25g SiC (size> 500 mesh) were dispersed at high speed in a sodium nitrate solution (the mass concentration of the sodium nitrate solution was 5%, the ultrasonic frequency was controlled to be 40kHz, and the power was 800kW) to form a suspension (the solid-liquid mass ratio of the suspension was 1:20); then the suspension was heated to 50°C, 58.2g nickel nitrate, 95.6g aluminum nitrate, 6.9g zirconium nitrate, 4.1g manganese nitrate, 7.6g cerium nitrate, and 12.3g ammonium molybdate were prepared into a precursor salt solution, and sodium carbonate was prepared as a precipitant solution (take The precursor salt is prepared at a molar ratio of 0.1:1 to sodium carbonate, preheated to 80°C by electric heating, and then added dropwise to the suspension in parallel (the addition is completed within 50 minutes, and the stirring speed is 600 rpm), the precipitation reaction is started, the pH of the solution is maintained at 7-8, and stirring is continued for 1 hour; a cobalt and zinc salt solution containing 5.8g of cobalt nitrate and 16.7g of zinc nitrate is added to the above solution, an alkaline precipitant is added, the pH of the solution is maintained at 7-8, and stirring is continued for 1-2 hours; the precipitate is subjected to multiple cycles of filter pressing, pulping, and washing until the conductivity of the filtrate is 50μS / cm, and then dried, and then calcined to obtain a catalyst powder; the calcination temperature is 600°C, the calcination time is 6 hours, and the calcination atmosphere is nitrogen.

[0082] Calculated by the mass of oxides, nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide account for 15%, 10%, 13%, 2%, 1%, 3%, 1.5% and 4.5% of the catalyst mass, respectively, and nitrogen-doped mesoporous carbon and SiC account for 25% of the catalyst mass, respectively.

[0083] WH-LS catalyst: The preparation method is the same as that of WH-HS catalyst, the difference lies in the different amounts of Mo, Co and Zn added.

[0084] The catalyst powder, calculated by the mass of oxides, is composed of nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide, which account for 25%, 5%, 40%, 4%, 1%, 3%, 0.5% and 1.5% of the catalyst mass respectively, and nitrogen-doped mesoporous carbon and SiC each account for 10% of the catalyst mass.

[0085] WH-HM catalyst: The preparation method is the same as that of WH-HS catalyst, but it does not contain Mo, Co, or Zn.

[0086] The catalyst powder, calculated by the mass of oxides, comprises nickel oxide, aluminum oxide, zirconium oxide, manganese oxide and cerium oxide, which account for 35%, 50%, 5%, 1% and 4% of the catalyst mass respectively; nitrogen-doped mesoporous carbon accounts for 2% of the catalyst mass; and SiC accounts for 3%.

[0087] Catalyst Performance Testing: The catalyst was reduced at 500°C for 10 hours and then evaluated for CO2 methanation performance. The reaction temperature was 250°C, the pressure was 2.5 MPa, and the feed gas composition was 20% CO, 80% H2, with an H2S content of 20 ppm. The results are shown in Table 1.

[0088] The reactor filling structure is: 2 layers of inert filler layers (M layer and N layer) and 6 layers of catalyst active layers (from top to bottom are A layer, B layer, C layer, D layer, E layer, and F layer). The first layer, A, is filled with WH-HS catalyst, which is in the shape of a four-hole wheel and has an outer diameter of 6mm. The second layer, B, is filled with WH-LS catalyst, which is cylindrical and has an outer diameter of 3mm. The third layer, C, has a loading ratio of 3:1 for WH-HM and WH-LS catalysts, both of which are spherical and have an outer diameter of 4mm. The fourth layer, D, has a loading ratio of 6:1 for WH-HM and WH-LS catalysts, and the fifth layer, E, has a loading ratio of 8:1 for WH-HM and WH-LS catalysts, both of which are cylindrical and have an outer diameter of 3mm. The sixth layer, F, has a loading ratio of 15:1 for WH-HM and WH-LS catalysts, both of which are spherical and have an outer diameter of 3mm. Catalyst loading performance test:

[0089] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, it is preheated to 250℃ and enters the catalyst active layer, the hot spot temperature appears in the third layer (C layer) with a temperature of 395℃, and the gas temperature after passing through the F layer is 285℃, the CO2 conversion rate is ≥99.5%, the CH4 selectivity is ≥99.5%, and it runs continuously for 1000h. The hot spot position has not moved significantly and the catalyst activity remains unchanged.

[0090] Example 6

[0091] WH-HS catalyst: 30 g nitrogen-doped mesoporous carbon (size > 500 mesh, 1100 m 2 / g, average pore size 5.5nm, nitrogen content 5%, of which pyridinic nitrogen 44.51%, pyrrolic nitrogen 26.59%, graphitic nitrogen 20.52%, oxidized nitrogen 8.38%) and 20g SiC (size>500 mesh) were dispersed at high speed in a sodium nitrate solution (the mass concentration of the sodium nitrate solution was 5%, the ultrasonic frequency was controlled to be 40kHz, and the power was 800kW) to form a suspension (the solid-liquid mass ratio of the suspension was 1:20); then the suspension was heated to 50°C, 58.2g nickel nitrate, 95.6g aluminum nitrate, 6.9g zirconium nitrate, 4.1g manganese nitrate, 7.6g cerium nitrate, and 12.3g ammonium molybdate were prepared into a precursor salt solution, and sodium carbonate was prepared as a precipitant solution (take The precursor salt is prepared at a molar ratio of 0.1:1 to sodium carbonate, preheated to 80°C by electric heating, and then added dropwise to the suspension in parallel (the addition is completed within 50 minutes, and the stirring speed is 600 rpm), the precipitation reaction is started, the pH of the solution is maintained at 7-8, and stirring is continued for 1 hour; a cobalt and zinc salt solution containing 5.8g of cobalt nitrate and 16.7g of zinc nitrate is added to the above solution, an alkaline precipitant is added, the pH of the solution is maintained at 7-8, and stirring is continued for 1-2 hours; the precipitate is subjected to multiple cycles of filter pressing, pulping, and washing until the conductivity of the filtrate is 50μS / cm, and then dried, and then calcined to obtain a catalyst powder; the calcination temperature is 600°C, the calcination time is 6 hours, and the calcination atmosphere is nitrogen.

[0092] Calculated by the mass of oxides, nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide account for 15%, 10%, 13%, 2%, 1%, 3%, 1.5% and 4.5% of the catalyst mass, respectively, and nitrogen-doped mesoporous carbon and SiC account for 30% and 20% of the catalyst mass, respectively.

[0093] WH-LS catalyst: The preparation method is the same as that of WH-HS catalyst, the difference lies in the different amounts of Mo, Co and Zn added.

[0094] The catalyst powder, calculated by the mass of oxides, nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide account for 25%, 5%, 40%, 4%, 1%, 3%, 0.5% and 1.5% of the catalyst mass, respectively, and nitrogen-doped mesoporous carbon and SiC account for 12% and 8% of the catalyst mass, respectively.

[0095] WH-HM catalyst: The preparation method is the same as that of WH-HS catalyst, but it does not contain Mo, Co, or Zn.

[0096] The catalyst powder, calculated by the mass of oxides, comprises nickel oxide, aluminum oxide, zirconium oxide, manganese oxide and cerium oxide, which account for 35%, 50%, 5%, 1% and 4% of the catalyst mass respectively; nitrogen-doped mesoporous carbon accounts for 1.5% of the catalyst mass; and SiC accounts for 3.5%.

[0097] Catalyst Performance Testing: The catalyst was reduced at 500°C for 10 hours and then evaluated for CO2 methanation performance. The reaction temperature was 250°C, the pressure was 2.5 MPa, and the feed gas composition was 20% CO, 80% H2, with an H2S content of 20 ppm. The results are shown in Table 1.

[0098] The reactor filling structure is: 2 layers of inert filler layers (M layer and N layer) and 6 layers of catalyst active layers (from top to bottom are A layer, B layer, C layer, D layer, E layer, and F layer). The first layer, A, is filled with WH-HS catalyst, which is in the shape of a four-hole wheel and has an outer diameter of 6mm. The second layer, B, is filled with WH-LS catalyst, which is cylindrical and has an outer diameter of 3mm. The third layer, C, has a loading ratio of 3:1 for WH-HM and WH-LS catalysts, both of which are spherical and have an outer diameter of 4mm. The fourth layer, D, has a loading ratio of 6:1 for WH-HM and WH-LS catalysts, and the fifth layer, E, has a loading ratio of 8:1 for WH-HM and WH-LS catalysts, both of which are cylindrical and have an outer diameter of 3mm. The sixth layer, F, has a loading ratio of 15:1 for WH-HM and WH-LS catalysts, both of which are spherical and have an outer diameter of 3mm. Catalyst loading performance test:

[0099] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, it is preheated to 250℃ and enters the catalyst active layer, the hot spot temperature appears in the third layer (C layer) with a temperature of 385℃, and the gas temperature after passing through the F layer is 280℃, the CO2 conversion rate is ≥99.5%, the CH4 selectivity is ≥99.5%, and it runs continuously for 1000h. The hot spot position has not moved significantly and the catalyst activity remains unchanged.

[0100] Example 7

[0101] WH-HS catalyst: 15 g nitrogen-doped mesoporous carbon (size > 500 mesh, 1100 m 2 / g, average pore size 5.5nm, nitrogen content 5%, of which pyridinic nitrogen 44.51%, pyrrolic nitrogen 26.59%, graphitic nitrogen 20.52%, oxidized nitrogen 8.38%) and 25g SiC (size>500 mesh) were dispersed at high speed in a sodium nitrate solution (the mass concentration of the sodium nitrate solution was 5%, the ultrasonic frequency was controlled to be 40kHz, and the power was 800kW) to form a suspension (the solid-liquid mass ratio of the suspension was 1:20); then the suspension was heated to 50°C, 58.2g nickel nitrate, 132.4g aluminum nitrate, 6.9g zirconium nitrate, 4.1g manganese nitrate, 7.6g cerium nitrate, and 15.9g ammonium molybdate were prepared into a precursor salt solution, and sodium carbonate was prepared as a precipitant solution (take The precursor salt is prepared at a molar ratio of 0.1:1 to sodium carbonate, preheated to 80°C by electric heating, and then added dropwise to the suspension in parallel (the addition is completed within 50 minutes, and the stirring speed is 600 rpm), and a precipitation reaction is started. The pH of the solution is maintained at 7-8 and stirring is continued for 1 hour. A cobalt and zinc salt solution containing 11.6 g of cobalt nitrate and 18.5 g of zinc nitrate is added to the above solution, and an alkaline precipitant is added to maintain the pH of the solution at 7-8. Stirring is continued for 1-2 hours. The precipitate is subjected to multiple cycles of filter pressing, pulping, and washing until the conductivity of the filtrate reaches 50 μS / cm, and then dried, and then calcined to obtain a catalyst powder. The calcination temperature is 600°C, the calcination time is 6 hours, and the calcination atmosphere is nitrogen.

[0102] Calculated by the mass of oxides, nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide account for 15%, 13%, 18%, 2%, 1%, 3%, 3% and 5% of the catalyst mass, respectively, and nitrogen-doped mesoporous carbon and SiC account for 15% and 25% of the catalyst mass, respectively.

[0103] WH-LS catalyst: The preparation method is the same as that of WH-HS catalyst, the difference lies in the different amounts of Mo, Co and Zn added.

[0104] The catalyst powder, calculated by the mass of oxides, is composed of nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide, which account for 27%, 5%, 36%, 4%, 1%, 3%, 0.5% and 1.5% of the catalyst mass, respectively; nitrogen-doped mesoporous carbon and SiC account for 12% and 10% of the catalyst mass, respectively.

[0105] WH-HM catalyst: The preparation method is the same as that of WH-HS catalyst, but it does not contain Mo, Co, or Zn.

[0106] The catalyst powder, calculated by the mass of oxides, comprises nickel oxide, aluminum oxide, zirconium oxide, manganese oxide and cerium oxide, which account for 35%, 50%, 5%, 2% and 3% of the catalyst mass respectively; nitrogen-doped mesoporous carbon accounts for 2.5% of the catalyst mass; and SiC accounts for 2.5%.

[0107] Catalyst Performance Testing: The catalyst was reduced at 500°C for 10 hours and then evaluated for CO2 methanation performance. The reaction temperature was 250°C, the pressure was 2.5 MPa, and the feed gas composition was 20% CO, 80% H2, with an H2S content of 20 ppm. The results are shown in Table 1.

[0108] The reactor filling structure is: 2 layers of inert filler layers (M layer and N layer) and 6 layers of catalyst active layers (from top to bottom are A layer, B layer, C layer, D layer, E layer, and F layer). The first layer, A, is filled with WH-HS catalyst, which is in the shape of a four-hole wheel and has an outer diameter of 6mm. The second layer, B, is filled with WH-LS catalyst, which is cylindrical and has an outer diameter of 3mm. The third layer, C, has a loading ratio of 3:1 for WH-HM and WH-LS catalysts, both of which are spherical and have an outer diameter of 4mm. The fourth layer, D, has a loading ratio of 5:1 for WH-HM and WH-LS catalysts, and the fifth layer, E, has a loading ratio of 6:1 for WH-HM and WH-LS catalysts, both of which are cylindrical and have an outer diameter of 3mm. The sixth layer, F, has a loading ratio of 12:1 for WH-HM and WH-LS catalysts, both of which are spherical and have an outer diameter of 3mm. Catalyst loading performance test:

[0109] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, it is preheated to 250℃ and enters the catalyst active layer, the hot spot temperature appears in the third layer (C layer) at a temperature of 390℃, and the gas temperature after passing through the F layer is 282℃, the CO2 conversion rate is ≥99.5%, the CH4 selectivity is ≥99.5%, and it runs continuously for 1000h. The hot spot position has not moved significantly and the catalyst activity remains unchanged.

[0110] Example 8

[0111] WH-HS catalyst: 14 g nitrogen-doped mesoporous carbon (size > 500 mesh, 1100 m 2 / g, average pore size 5.5nm, nitrogen content 5%, of which pyridinic nitrogen 44.51%, pyrrolic nitrogen 26.59%, graphitic nitrogen 20.52%, oxidized nitrogen 8.38%) and 26g SiC (size> 500 mesh) were dispersed at high speed in a sodium nitrate solution (the mass concentration of the sodium nitrate solution was 5%, the ultrasonic frequency was controlled to be 40kHz, and the power was 800kW) to form a suspension (the solid-liquid mass ratio of the suspension was 1:20); then the suspension was heated to 50°C, 54.3g nickel nitrate, 132.4g aluminum nitrate, 6.9g zirconium nitrate, 4.1g manganese nitrate, 7.6g cerium nitrate, and 17.2g ammonium molybdate were prepared into a precursor salt solution, and sodium carbonate was prepared as a precipitant solution (take The precursor salt is prepared at a molar ratio of 0.1:1 to sodium carbonate, preheated to 80°C by electric heating, and then added dropwise to the suspension in parallel (the addition is completed within 50 minutes, and the stirring speed is 600 rpm), and a precipitation reaction is started. The pH of the solution is maintained at 7-8 and stirring is continued for 1 hour. A cobalt and zinc salt solution containing 11.6 g of cobalt nitrate and 18.5 g of zinc nitrate is added to the above solution, and an alkaline precipitant is added to maintain the pH of the solution at 7-8. Stirring is continued for 1-2 hours. The precipitate is subjected to multiple cycles of filter pressing, pulping, and washing until the conductivity of the filtrate reaches 50 μS / cm, and then dried, and then calcined to obtain a catalyst powder. The calcination temperature is 600°C, the calcination time is 6 hours, and the calcination atmosphere is nitrogen.

[0112] Calculated by the mass of oxides, nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide account for 14%, 14%, 18%, 2%, 1%, 3%, 3% and 5% of the catalyst mass, respectively, and nitrogen-doped mesoporous carbon and SiC account for 14% and 26% of the catalyst mass, respectively.

[0113] WH-LS catalyst: The preparation method is the same as that of WH-HS catalyst, the difference lies in the different amounts of Mo, Co and Zn added.

[0114] The catalyst powder, calculated by the mass of oxides, is composed of nickel oxide, molybdenum oxide, aluminum oxide, zirconium oxide, manganese oxide, cerium oxide, cobalt oxide and zinc oxide, accounting for 25%, 5%, 38%, 4%, 1%, 3%, 0.5% and 1.5% of the catalyst mass, respectively; nitrogen-doped mesoporous carbon and SiC account for 11% and 11% of the catalyst mass, respectively.

[0115] WH-HM catalyst: The preparation method is the same as that of WH-HS catalyst, but it does not contain Mo, Co, or Zn.

[0116] The catalyst powder, calculated by the mass of oxides, comprises nickel oxide, aluminum oxide, zirconium oxide, manganese oxide and cerium oxide, which account for 38%, 47%, 5%, 2% and 3% of the catalyst mass respectively; nitrogen-doped mesoporous carbon accounts for 2% of the catalyst mass; and SiC accounts for 3%.

[0117] Catalyst Performance Testing: The catalyst was reduced at 500°C for 10 hours and then evaluated for CO2 methanation performance. The reaction temperature was 250°C, the pressure was 2.5 MPa, and the feed gas composition was 20% CO, 80% H2, with an H2S content of 20 ppm. The results are shown in Table 1.

[0118] The reactor filling structure is: 2 layers of inert filler layers (M layer and N layer) and 6 layers of catalyst active layers (from top to bottom are A layer, B layer, C layer, D layer, E layer, and F layer). The first layer, layer A, is filled with a WH-HS catalyst in a four-hole cartwheel shape with an outer diameter of 6mm. The second layer, layer B, is filled with a WH-LS catalyst in a cylindrical shape with an outer diameter of 3mm. The third layer, layer C, has a 3:1 loading ratio of WH-HM to WH-LS catalysts, both of which are spherical and have an outer diameter of 4mm. The fourth layer, layer D, has a 5:1 loading ratio of WH-HM to WH-LS catalysts, and the fifth layer, layer E, has a 6:1 loading ratio of WH-HM to WH-LS catalysts, both of which are cylindrical and have an outer diameter of 3mm. The sixth layer, layer F, has a 12:1 loading ratio of WH-HM to WH-LS catalysts, both of which are spherical and have an outer diameter of 3mm.

[0119] Catalyst loading performance test:

[0120] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, and it is preheated to 250℃ before entering the catalyst active layer. The hot spot temperature appears in the third layer (C layer) with a temperature of 388℃. After passing through the F layer, the gas temperature is 283℃, the CO2 conversion rate is ≥99.5%, the CH4 selectivity is ≥99.5%, and it runs continuously for 1000h. The hot spot position has not moved significantly and the catalyst activity remains unchanged.

[0121] Comparative Example 1

[0122] The catalyst is the same as in Example 1

[0123] The filling structure of the reactor is: two layers of inert filler (M layer and N layer) and one layer of catalyst active layer are used, all of which are filled with WH-HS catalyst, and the catalysts used are all spherical in shape.

[0124] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, it is preheated to 250℃ and enters the catalyst active layer, the hot spot temperature appears at 3 / 5 of the catalyst bed height, the temperature is 305℃, the gas temperature after passing through bed F is 220℃, the CO2 conversion rate is ≥42.5%, the CH4 selectivity is ≥95.5%, and it runs continuously for 1000h without changing the hot spot position and catalyst activity.

[0125] Comparative Example 2

[0126] The catalyst is the same as in Example 1

[0127] The filling structure of the reactor is: using two layers of inert filler layers (M layer and N layer) and one layer of catalyst active layer, all filled with WH-LS catalyst, and the catalyst used is cylindrical in shape.

[0128] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, and the rest are N2 / CH4 and other components. The H2S content is 5ppm. It is preheated to 250℃ and enters the catalyst active layer. The hot spot temperature appears at the first 1 / 6 of the catalyst bed height, and the temperature is 365℃. After passing through the bed, the gas temperature is 270℃, the CO2 conversion rate is ≥80.5%, and the CH4 selectivity is ≥98.5%. After continuous operation for 1000h, the hot spot position moves slightly downward, the hot spot temperature is 360℃, the CO2 conversion rate is ≥75.5%, and the CH4 selectivity is ≥98.5%.

[0129] Comparative Example 3

[0130] The filling structure of the reactor is: using two layers of inert filler layers (M layer and N layer) and one layer of catalyst active layer, all filled with WH-HM catalyst, and the catalysts used are all cylindrical in shape.

[0131] The reaction pressure was 2.5 MPa, and the feed gas composition was 15% CO2, with a hydrogen-to-carbon ratio of 4:1, the remainder being N2 / CH4 and other components. The H2S content was 5 ppm. After preheating to 250°C and entering the catalyst active layer, the hotspot temperature appeared at 350°C at the 1 / 8 position of the catalyst bed. After passing through the bed, the gas temperature was 280°C, with a CO2 conversion rate ≥98.5% and a CH4 selectivity ≥99.5%. After 200 hours, the hotspot position shifted down to approximately 310°C at the 1 / 2 position of the bed. After passing through bed F, the gas temperature was 220°C, with a CO2 conversion rate ≥50.5% and a CH4 selectivity ≥99.5%. This indicates that the high-activity catalyst, which is not sulfur-tolerant, has poor stability in a hydrogen sulfide atmosphere.

[0132] Comparative Example 4

[0133] The filling structure of the reactor is: two layers of inert filler layers (M layer and N layer) and one layer of catalyst active layer. The ratio of WH-HS catalyst to WH-LS catalyst in the active layer is 1:1. The WH-HS catalyst is shaped like a four-hole wheel with an outer diameter of 6 mm, and the WH-LS catalyst is shaped like a four-hole wheel with an outer diameter of 6 mm.

[0134] The reaction pressure is 2.5 MPa, the raw gas composition is 15% -CO2, the hydrogen-carbon ratio is 4:1, the rest is N2 / CH4 and other components, the H2S content is 5 ppm, preheated to 250 ° C before entering the catalyst active layer, the hot spot temperature appears in the first 1 / 3 of the catalyst bed, the temperature is 355 ° C, the gas temperature after passing through the bed is 275 ° C, the CO2 conversion rate is ≥96.5%, the CH4 selectivity is ≥93.5%, and the hot spot temperature, position and catalyst activity remain basically unchanged after 1000 hours of continuous operation.

[0135] The WH-HS catalyst is the same as that in Example 1, except that it does not contain the Co-Zn coating.

[0136] The catalyst loading ratio is the same as that in Example 1.

[0137] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, it is preheated to 250℃ and enters the catalyst active layer, the hot spot temperature appears in the third layer (layer C) with a temperature of 385℃, and the gas temperature after passing through bed F is 280℃, the CO2 conversion rate is ≥99.5%, the CH4 selectivity is ≥99.5%, and after continuous operation for 1000h, the hot spot position shifts slightly downward, the hot spot temperature drops to 375℃, the catalyst activity decreases, the CO2 conversion rate is ≥93.5%, and the CH4 selectivity is ≥99.5%.

[0138] Comparative Example 6

[0139] The WH-HS catalyst is the same as that in Example 1, except that it does not contain Mo.

[0140] The catalyst loading ratio is the same as that in Example 1

[0141] The reaction pressure is 2.5MPa, the raw gas composition is 15%-CO2, the hydrogen-carbon ratio is 4:1, the rest are N2 / CH4 and other components, the H2S content is 5ppm, it is preheated to 250℃ and enters the catalyst active layer, the hot spot temperature appears in the third layer (layer C) with a temperature of 385℃, and the gas temperature after passing through bed F is 280℃, the CO2 conversion rate is ≥99.5%, the CH4 selectivity is ≥99.5%, and after continuous operation for 1000h, the hot spot position shifts slightly downward, the hot spot temperature drops to 370℃, the catalyst activity decreases significantly, the CO2 conversion rate is ≥82.5%, and the CH4 selectivity is ≥99.5%.

[0142] Evaluations of the sulfur-tolerance activity of the catalysts in Examples 1-8 and Comparative Examples 1-6 and their actual loading and application indicate that both the active component, Mo, and the Co-Zn coating enhance the catalyst's sulfur tolerance. Long-term use of a single catalyst results in poor sulfur-tolerance stability for the highly active catalyst, while the activity and selectivity of the sulfur-tolerant catalyst are relatively low. By mixing the three catalysts in varying proportions and sequences, the bed heats up slowly, the hotspot temperature is controllable, reaction activity is high, methane selectivity is high, and the overall catalyst bed exhibits excellent sulfur-tolerance stability.

[0143] Table 1 Catalyst evaluation results

[0144]

Claims

1. An application of a catalyst, characterized in that: A catalyst active layer is loaded in the reactor, and an inert filler layer is arranged at both ends of the catalyst active layer. The catalyst active layers are 3 to 6 layers, all of which are arranged along the airflow direction. The catalyst active layer of the first layer is a WH-HS catalyst, the catalyst active layer of the second layer is a WH-LS catalyst, and the catalyst active layers of the remaining layers are mixed catalysts of WH-HM catalyst and WH-LS catalyst. The mass ratio of the WH-HM catalyst to the WH-LS catalyst is 3:0.1 to 1, and the mass ratio of the WH-HM catalyst increases layer by layer along the airflow direction. The catalysts in the catalyst active layers of the same layer have the same shape. The reactor is a shell-and-tube temperature-controlled reactor, the catalyst is loaded in the shell layer, and the water channel supplies and removes heat through the tube layer. The WH-HS catalyst is a highly sulfur-resistant methanation catalyst. The catalyst comprises: Al2O3 and ZrO2 as supports, with the Al2O3 content being 10-30wt% and the ZrO2 content being 2-5wt% based on the total weight percentage of the catalyst; nitrogen-doped mesoporous carbon and silicon carbide as support modifiers, with the support modifier content being 40-70wt% and the nitrogen-doped mesoporous carbon:silicon carbide mass ratio being 1-3:1-3; NiO and MoO3 as active components, with the active component content being 10-30wt% and the NiO:MoO3 mass ratio being 1-3:1; CeO2 and MnO2 as auxiliary agents, with the auxiliary content being 1-5wt% and the CeO2:MnO2 mass ratio being 1-5:1; and a Co-Zn coating with a content of 5-10wt% and a CoO:ZnO mass ratio being 1:1-3. The WH-LS catalyst is a low-sulfur-tolerant methanation catalyst. The catalyst comprises the following components, calculated as a percentage by weight of the total catalyst: Al2O3 and ZrO2 as supports, with the Al2O3 content being 20-50wt% and the ZrO2 content being 2-10wt%; support modifiers being nitrogen-doped mesoporous carbon and silicon carbide, with the support modifier content being 15-30wt%, and the nitrogen-doped mesoporous carbon:silicon carbide mass ratio being 1-3:1-3; active components being NiO and MoO3, with the active component content being 20-40wt%, and the NiO:MoO3 mass ratio being 5-10:1; additives being CeO2 and MnO2, with the additive content being 1-5wt%, and the CeO2:MnO2 mass ratio being 1-5:1; a Co-Zn coating having a content of 1-5wt%, and a CoO:ZnO mass ratio being 1:1-3; The WH-HM catalyst is a highly active methanation catalyst. Calculated by weight percentage of the total catalyst, the carriers are Al2O3 and ZrO2, with the Al2O3 content being 40-60wt% and the ZrO2 content being 2-10wt%; the carrier modifiers are nitrogen-doped mesoporous carbon and silicon carbide, with the carrier modifier content being 1-10wt%, and the mass ratio of nitrogen-doped mesoporous carbon to silicon carbide being 1-3:1-3; the active component is NiO, with the active component NiO content being 25-50wt%; the additives are CeO2 and MnO2, with the additive content being 1-5wt%, and the mass ratio of CeO2 to MnO2 being 1-5:

1.

2. The use of the catalyst according to claim 1, characterized in that: In the reactor, the bed temperature is 240-290° C., the hot spot temperature is 380-500° C., and the outflow temperature of the reactor gas outlet is 250-300° C.

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