A research on the synthesis process of Zr-MOF derived Ni-based catalysts for CO2 methanation: The role of Ce promoter, method of Ni introduction and calcination condition

CO 2 methanation is a potential way for the re-utilization of CO 2 . MOF derivations are promising candidates for commonly used Ni-based catalysts due to their high porosity and confinement effect. Herein, we systematically investigated the synthetic pathway of Zr-MOF-derived Ni-based catalysts. It is found that Ce addition can effectively improve the thermostability, specific surface area and Ni dispersion of the derived Ni/CeO 2 -ZrO 2 catalyst. It can also enhance the adsorption of CO 2 by the generation of O v and improve CO 2 methanation activity. Calcination the MOF in inert gas leads to the formation of CNTs and amorphous carbon. Amorphous carbon results in less interaction between NiO and CeO 2 as well as low amount of O v , leading to lower catalytic activity than the catalyst calcinated in air. Compared with impregnation method, one-pot solvothermal method leads to much higher specific surface area for both MOF and derived oxides. It also benefits the uniform dispersion of NiO and higher amount of O v . Therefore, it shows better catalytic activity and is proved to be a better method for Ni introduction. In the catalysts we discussed, St-ZrCeNi (Ce addition, one-pot solvothermal method, calcination in air) shows the highest CO 2 conversion and good CH 4 selectivity due to its high specific area and more O v . It also shows good stability (>50 h) and good intrinsic activity. This research reveals the roles of several important factors in the synthesis process of Zr-MOF derived Ni-based catalysts. It also gives new insights for the design and synthesis for other MOF derived catalysts.