The selective conversion of NOx to NH3 through the NO – CO - H2O reaction over Pt/TiO2 catalysts was investigated to develop a method for utilizing reactive nitrogen species emitted from combustion processes as raw materials for the synthesis of useful compounds. High NH3 selectivity was achieved for high-specific-surface-area catalysts. Catalytic activity tests showed that the activities of catalysts depended on the crystal structure of the support. Comparing CO conversion between NO – CO - H2O reaction and CO - H2O reaction, which could play a role of H-supply reaction, Pt/TiO3 demonstrated higher CO conversion for the NO – CO - H3O reaction than that for CO - H2O reaction except for high-surface-area anatase TiO2-supported catalyst around 200°C. Temperature-programmed desorption of CO2 revealed that the CO3 formed during the NO – CO - H2O reaction had no effect on the difference in activity. Carbonaceous surface species and NHx species were observed on the surface of Pt/TiO2 catalyst during NO – CO - H2O reaction by diffused reflectance infrared Fourier transform spectroscopy. The difference in formate formation on anatase-TiO2 supported Pt catalyst was confirmed compared to rutile-TiO2 supported Pt catalyst.
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