Morphology dependence of catalytic properties of Ni/CeO2 for CO2 methanation: A kinetic and mechanism study

Ceria has been used for catalyst support for long time due to its unique structural properties resulting from oxygen vacancies and reversible valence change (Ce4+ and Ce3+). In this report, ceria nanorods (NR) and nanocubs (NC) were prepared with hydrothermal method and 5 wt% nickel was loaded on it. The effect of morphology of ceria supports for CO2 methanation reaction was studied. Characterization including TPR, TEM, XRD and XPS shows that Ni/CeO2-NR had a higher number of Ce3+ proportion compared with Ni/CeO2-NC. Both catalysts showed high conversion and selectivity for methane at low temperature range at200–250 °C and interestingly Ni/CeO2-NR exhibited a higher activity than Ni/CeO2–NC. A kinetic study and DRIFTs investigation were carried out to formulate the mechanism. It turned out that CO2 methanation on Ni/CeO2 goes through a formate route instead of CO2 dissociation and the oxygen vacant sites are supposed to be the active sites for the formate formation in this mechanism.