Preparation Of Catalysts Of Ni-La/Al₂O₃-ZrO₂ And Study On Their CO Methanation Performance

China has the"rich coal,lean oil,less gas"energy structure,the development of coal as raw material of coal to product natural gas is to improve China's energy structure and achieve an important way to clean coal use.The core process of coal gas is Methanation of synthesis gas,Ni/Al₂O₃ is a methanation catalyst which has been applied industrially.However,the activity of Ni/Al₂O₃ catalyst,the anti-carbon and anti-sintering ability are still the main problems that need to be solved.In this paper,Al2O3-Zr O2 composite oxide carrier was prepared by hydrolysis precipitation method,And the perovskite-type composite oxide La Ni O3 with specific composition was supported on the Zr O2-Al2O3composite oxide carrier by citric acid complexation method,Ni-La/Al2O3-Zr O2 catalyst was prepared,The presence state of Ni?La before and after reduction was studied,by adjusting the composition and structure of Ni and La nanoparticles,a nano-metal catalyst with high resistance to sintering and carbon deposition.Carrier calcination temperature affects the carrier and catalyst structure,The carrier forms a solid solution with atomic intermixation and intergranular interpenetrationwhen calcined temperature at 700°C and more easy to form La Ni O₃active component with perovskite structure.Compared with the high dispersion of Ni O,the reduction of La Ni O₃ with perovskite structure is more favorable for methanation,When the reaction temperature is 400?,the CO conversion of 20L-N/AZ700 catalyst is close to 100%,and the selectivity and yield of CH₄ are reached 99.8%.The loading of La-Ni affects the state of Ni and the reduction state,Wherein the amount of La Ni O₃ in the 30L-N/AZ700 catalyst is more than 20L-N/AZ700 catalyst,So behaved better stability,the main reason to maintain the stability of the catalyst is the La₂O₃ obstructed Ni particles thus inhibit the Ni sintering when La Ni O₃ reduced.The reduced Ni⁰ particle size is reduced after the reduction of the temperature,The larger particle size of Ni⁰ favors the low temperature activity of CO methanation,while the small Ni⁰ particle size facilitates the stable conversion of CO.The addition of MgO and GaO promoter enhances the interaction of the metal-support in the catalyst,And prevented the formation of La Ni O₃.Compared with the catalyst without the addition of promoter,the addition of promoter makes the catalyst low temperature activity and selectivity is poor.The preparation method affects the reduction of Ni,The catalyst prepared by citric acid complex is not easy to form nickel aluminum spinel,Which is beneficial to improve the reduction performance of Ni species,Improve the utilization of active components.The reduction of Ni in the catalyst prepared by the coprecipitation method favors the low activity of CO methanation,The reduction of Ni,which is strongly interacting with the support,favors high temperature activity.