Calcined sepiolite-supported Pt/Fe catalyst

Calcined sepiolite-supported Pt (Pt/CSp) catalysts indicate the high activity for complete oxidation of hydrocarbons (HC). The simultaneous oxidation of HC and SO2 on the Fe-impregnated calcined sepiolite-supported Pt (Pt/Fe-CSp) catalysts was studied in comparison with that on Pt/CSp catalysts. There was a negligible difference in HC activity. Nevertheless, SO2 oxidation activity on the Pt/Fe-CSp catalyst was suppressed more than that on the Pt/CSp catalyst. The calcination temperature of sepiolite affects the quantity of Fe additive. XRD and NMR show that the quantity of Fe additive depends on the distortion of the local structure of the calcined sepiolite. At the same time, the quantity of Fe additive affects the SO2 oxidation activity. Fresh Pt/Fe-CSp catalyst absorbs SO2. The absorbed SO2 reacted with Mg of CSp to form MgSO4 on the catalyst. After this absorption was saturated, the selectivity of the oxidation was maintained. XPS and Mِssbauer spectroscopy show that most of Fe on the Pt/Fe-CSp catalyst is Fe3+. Pulsed chemisorption analysis of the redox cycle shows that Fe on the calcined sepiolite has a high oxygen storage capacity (OSC). This redox reaction suggests the mechanism of this selective oxidation reaction. The selective oxidation property is expected to be useful for a catalyst of purification for exhaust gas from a boiler or a combustion engine using a fuel which contains sulfur.