Catalytic performance of Pt–Sn/γ-Al2O3 for diesel soot oxidation

The effect of tin addition to a Pt/γ-Al2O3 catalyst and the influence of pre-sulfating the catalysts on the activity in diesel soot oxidation were studied. Results obtained in this investigation revealed that pre-sulfating γ-Al2O3, 1%Pt/γ-Al2O3, and 1%Pt–2%Sn/γ-Al2O3 catalyst resulted in the generation of surface sites active at low temperature in the oxidation of a fraction of soot particles produced during diesel combustion. These active sites may be alumina sulfate species that increase the support acidity. Tin addition to 1%Pt/γ-Al2O3 resulted in an increase of platinum resistance to deactivation due to carbonaceous deposits during diesel soot oxidation. This effect is explained on basis of XPS determinations that showed the presence of high amounts of Sn species over the catalyst surface that may prevent polymerized hydrocarbon residues to reach the interface between platinum and the support.