Construction Of Low-temperature And High-efficiency CO₂ Methanation Catalyst Based On Mesoporous Ni-Ce-based Hollow Nanosphere

CO₂ methanation is a process to acquired clean energy CH₄ with high calorific value by using CO₂ and renewable hydrogen energy as raw materials.This process can not only reduce the energy consumption of coal,oil,and other traditional fossil,but also is of great significance to carbon emission reduction.It is usually to use highly efficient catalysts to achieve high conversion of CO₂ in the low reaction temperature range due to the high energy barrier in the kinetics of CO₂ methanation.Nickel-based catalysts have become the most popular CO₂methanation catalysts because of the advantages,such as low price,high temperature activity comparable to precious metal catalysts.In addition,CeO₂ has become one of the most important catalyst support attributed to its abundant surface oxygen vacancies and good oxygen storage capacity.Therefore,the development of efficient and stable Ni-Ce-based low temperature CO₂methanation catalysts has always been a challenging subject in the field of environmental catalysis.However,there is still some lack of exploration on the structure-activity relationship of Ni-Ce-based catalysts at present,such as mesoporous Ni-CeO₂ nano-hollow spheres.The CeO₂ mesoporous structure with large specific surface area,large pore volume and regular pore structure is conducive to the high dispersion of metal Ni active sites,which could provide many active sites for reactants and improve catalytic efficiency.At the same time,combined it with hollow sphere structure with excellent stability and contact ability could improve the low temperature activity and stability of the catalyst.Therefore,in this study,the hollow spherical mesoporous Ni-Ce-based nanomaterials were synthesized and then tested their CO₂methanation catalytic performance.The effects of different influence factors on the morphology and surface structure of the catalyst combined with thermogravimetric mass spectrometry（TG-MS）and in situ diffuse reflection Fourier transform infrared spectroscopy（in-situ DRIFTS）etc.technology would be explored to adjust the catalytic performance and establish the structure-activity relationship.The research work is mainly divided into several aspects:（1）Mesoporous Ni-CeO₂ catalyst with nano-hollow sphere structure were synthesized by‘one-pot’method.The catalyst morphology,surface physical and chemical properties,and CO₂methanation catalytic performance were investigated on different Ni loading amount,calcination temperature,and salt precursor.（2）The mesoporous Ni-CeM（M=Co,Cu,Mn）nano-hollow spherical catalysts doped with a series of transition metals were synthesized.The impact of doped transition metals on the morphology,surface physicochemical properties,and catalytic performance of CO₂methanation were investigated.The optimal active transition metal was selected to investigate the influence of its doping amount on the morphology and surface properties of low temperature and high efficiency CO₂ methanation catalyst.（3）The mesoporous Ni-CeM（rare metals M=La,Pr,Sm）nano-hollow spherical catalysts were synthesized.The optimal active rare metal was selected to optimized the morphology,surface physicochemical properties,and catalytic performance of CO₂ methanation.The impact of its doping amount on the morphology and surface properties of CO₂ methanation catalyst were studied.