Higher catalytic activity of nano-Ce1-x-yTixPdyO2-δ compared to nano-Ce1-x PdxO2-δ for CO oxidation and N2O and NO reduction by CO:: Role of oxide ion vacancy

Nano-Ce0.73Ti0.25Pd0.02O2-delta solid solution, prepared by solution combustion method, has been synthesized. The catalyst has been characterized by XRD, HRTEM and XPS. Synergistic interaction of Pd with Ti/Ce is very strong because of ionic substitution. The reducibility of Ce0.73Ti0.25Pd0.02O2-delta is about 5 times higher compared to that of Ce0.98Pd0.02O2-delta below 140 degrees C. The easy removal of oxygen from the more reducible Ti containing support plays a major role in showing higher catalytic activity of this material for CO oxidation and N2O and NO reduction by CO. The catalyst shows 100% N-2 selectivity above 240 degrees C and high reaction rates compared to other catalysts reported in the literature. It has been shown that oxide ion vacancy creation in the support promotes the adsorption and dissociation of NO or N2O at a lower temperature. Kinetic models based on a bifunctional mechanism were used to determine the reaction rate coefficients.