Effects of Morphology of Cerium Oxide Catalysts for Reverse Water Gas Shift Reaction

Reverse water gas shift reaction (RWGS) was investigated over cerium oxide catalysts of distinct morphologies: cubes, rods and particles. Catalysts were characterized by X-ray diffraction, Raman spectroscopy and temperature programmed reduction (TPR) in hydrogen. Nanoshapes with high concentration of oxygen vacancies contain less surface oxygen removable in TPR. Cerium oxide cubes exhibited two times higher activity per surface area as compared to rods and particles. Catalytic activity of these nanoshapes in RWGS reaction exhibited a relation with the lattice microstrain increase, however a causal relationship remained unclear. Results presented in this study suggest that superior catalytic activity of ceria cubes in RWGS originates from the greater inherent reactivity of (100) crystal planes enclosing cubes, contrary to less inherently reactive (111) facets exposed at rods and particles.