Selective NOx reduction in H2 + NO + O2 reaction under oxygen-rich condition over Pt/rare earth oxide catalysts

The Pt supported rare earth oxide (CeO2, Pr6O11, Eu2O3, Gd2O3) catalysts were prepared by a conventional impregnation method to evaluate their selective catalytic reduction properties of NOx with H-2 under excess oxygen condition. Among them, good NOx reduction activity was obtained only on the Pt/CeO2 catalyst. Specific adsorption peaks assigned to NO3- species were observed in its diffuse reflectance infrared Fourier transform spectrum (DRIFTs) for the Pt/CeO2 catalyst, indicating that NOx reduction proceeds via formation of such nitrate. DeNO(x) properties of Pt/CeO2 were further improved by using a solvothermal deposition technique. The catalyst prepared by physically mixing the CeO2 support with Pt particles deposited by a solvothermal method, consequently, gave the best deNO(x) performance (NO conversion: ca. 80%, N-2 selectivity: ca. 75%).