ZHANG Xiaoli;GU Fangna;SU Fangbing;XU Guangwen;Key Laboratory on Resources Chemicals and Materials of Ministry Education,Shenyang University of Chemical Technology;State Key Laboratory of Multiphase Complex Systems,Institute of process Engineering,Chinese Academy of Sciences;Institute of Industrial Chemistry and Energy Technology,Shenyang University of Chemical Technology;Carbon dioxide methanation is a promising technology for realizing the recycling of CO_2 and solving the environmental problems caused by CO_2 emissions. Ni-based catalysts have been widely used in CO_2 methanation in recent years because of their good catalytic activity, high CH_4 selectivity, and low price. The effects of Ni particle size effect, surface microstructure, support type and physicochemical properties(alkaline site, oxygen vacancy, specific surface area, pore structure and metal support interaction) on the catalytic performance of CO_2 methanation catalyst were emphatically described. The effects of Ni-based bimetallic alloy, structure and electronic additives on its catalytic performance were introduced, the CO_2 methanation mechanism on different catalysts were summarized, the reasons for the deactivation of Ni based catalysts were analyzed, and the application of Ni-based catalysts in photothermal catalytic CO_2 methanation was discussed. Finally, the future research direction of CO_2 methanation catalyst has been prospected. By comparing the results of different systems, it reveals that the CO_2 methanation is a structure-sensitive reaction, in which Ni particle size has significant effect on the activity of the catalysts. However, the optimum Ni particle sizes obtained by different studies are various, which may be related to the difference of the surface microstructure(such as different crystal planes, defect sites, etc.) of Ni particles caused by the different interaction between metals and carriers or preparation methods. Thus, the size effect of Ni particles remains to be further studied. Moreover, the activity and stability of the Ni catalysts can also be improved by adding the second metal or promoters, or tuning the interaction between Ni particles and carriers. The abundant alkaline sites and oxygen vacancies on the surface of the support are conducive to CO_2 adsorption and activation, so as to improve the activity of the catalyst. At present, the proposed mechanisms of CO_2 methanation over Ni-based catalysts are mainly classified into CO pathway and formate pathway, which pathway followed may relate to the surface properties of the catalysts(such as the concentration of hydroxyl or O~(2-)adsorption site, etc.) and reaction conditions(such as temperature, pressure, etc.). However, there is a lack of in-depth cognition about the nano-interface structure between promoters or carriers and Ni species, and the influence mechanism of different promoters and carriers on the catalytic active sites and the pathway of CO_2 methanation. Therefore, it is necessary to make a fine and dynamic structural analysis of the surface interface geometry and electronic structure of the Ni-based catalyst using a series of in-situ imaging and spectroscopy techniques, and establish a dynamic structure activity relationship between structure and performance, which is conducive to the understanding of the above problems, and can also guide the design and synthesis of highly efficient Ni-based catalysts with specific structures.
2022 04 v.28;No.140 [Abstract][OnlineView][HTML全文][Download 25037K]