Properties of platinum-containing glass-fiber catalysts in the SO2 oxidation reaction

SO2 oxidation catalysts containing small amounts (0.01–0.03 mass%) of platinum at the zirconia-promoted silica glass fibers (Pt-GFCs) demonstrate relatively high activity at moderate temperatures (below 400 °C) and the appropriate thermal stability (up to 700 °C). The catalytic activity of Pt-GFC in the SO2 oxidation reaction is provided by the small (< 1 nm) partially charged platinum clusters, while platinum in a form of large metal particles is practically inactive. Pt-GFCs have the high (up to ~20 mass%) sorption capacity with respect to SO2. Such sorption occurs via the interaction of SO2 with oxygen, either present in the gaseous reaction mixture or pre-adsorbed in the fresh GFC structure, with the possible formation of the intermediate sulfates in the glass bulk of the catalyst. Besides, Pt-GFC may effectively oxidize CO in the presence of significant amounts of sulfur dioxide.