Defective ceria created by oxy-hydrogen flame and its influences on Pt dispersion, Pt-ceria interaction and catalytic hydrogenation

We employed an oxy-hydrogen flame to create defective ceria and studied the consequent changes in the physiochemical properties of ceria and ceria-supported platinum (Pt) catalysts. The defective ceria is more reduced and has greater redox capabilities than the pristine sample. The defective ceria supported Pt catalysts have stronger metal-support interactions that lead to higher Pt dispersion and chemoselectivity in 3-nitrostyrene hydrogenation compared to ceria-supported platinum catalysts. The chemoselectivity increases and then decreases with decrease in metal loadings in defective ceria supported Pt catalysts, while it monotonically increases with decreasing metal loadings in ceria-supported catalysts. The diminishing chemoselectivity of defective ceria supported catalysts can be attributed to the more reduced nature of the defective ceria that leads to metal nanoclusters with less positive charge, disfavoring adsorption of the negatively charged nitro-groups in 3-nitrostyrene in the reaction. Such effect is not obvious in the defective ceria supported catalysts with higher Pt loadings (i.e., larger Pt particle sizes).