Three types of platinum catalysts, Pt/SiO2, Pt/γ-Al2O3 and Pt/ZrO2 were examined for the oxidation of NO to NO2 of SO2 to SO3. The activity order for both oxidation reactions was found to be: Pt/SiO2>Pt/γ-Al2O3>Pt/ZrO2. The effect of Pt loading and Pt dispersion on the catalytic activity and selectivity was examined. Over Pt/SiO2, the specific activities were found to be strongly size-dependent, the larger Pt particles exhibiting higher specific activity than the smaller ones. Over the Pt/γ-Al2O3 catalysts, however, the size-dependence appeared to be much less significant than that of the Pt/SiO2 catalysts. The results for Pt/ZrO2 catalysts, however, showed that the specific activities for both reactions were most probably size-independent. The catalytic selectivity for the oxidation of NO relative to that of SO2 appeared to be size-independent for all the catalysts. The interaction of NO, NO2 and SO2 with the catalysts and the effect of the support on the interaction were investigated using TPD technique.
Xue, E., Seshan, K., & Ross, J. R. H. (1996). Roles of supports, Pt loading and Pt dispersion in the oxidation of NO to NO2 and of SO2 to SO3. Applied catalysis B: environmental, 11(11), 65-79. https://doi.org/10.1016/S0926-3373(96)00034-3