Deep oxidation of propane using palladium–titania catalysts modified by niobium

Pd/TiO2 catalysts modified by niobium have been prepared and tested for the complete oxidation of propane. The catalysts have been characterised by BET, XRD, laser Raman spectroscopy, XPS, DRS and TPR. The incorporation of niobium into Pd/TiO2 catalysts resulted in a marked increase in the catalytic activity compared to the Nb-free Pd/TiO2 catalysts, and the activity increased as the niobium and/or palladium loading increased. The addition of Nb significantly modified the nature of the palladium and niobium species. There was a marked increase in the oxygen mobility after niobium addition. This could not only promote the presence of palladium species in a totally oxidized state but also resulted in the formation of new and very easily reducible species identified by subambient TPR. It was concluded that the niobium synergistic effect is due to the presence of these active oxygen species.

The activity of Pd/TiO2 catalysts for the total oxidation of propane is enhanced by the addition of niobium. The most active catalyst was 0.5 wt.% palladium promoted with 6.0 wt.% niobium. The addition of niobium did not affect the dispersion of palladium, but did increase the concentration of surface oxidized palladium and generated highly active oxygen species that were characterised by subambient TPR.Figure optionsDownload as PowerPoint slide