Comparative XPS study of Al2O3 and CeO2 sulfation in reactions with SO2, SO2+O2, SO2+H2O, and SO2+O2+H2O

The interactions of Al2O3, CeO2, Pt/Al2O3, and Pt/CeO2 films with SO2, SO2 + H2O, SO2 + O-2, and SO2 + O-2 + H2O in the temperature range 300-673 K at the partial pressures of SO2, O-2, and H2O equal to 1.5 x 10(2), 1.5 x 10(2), and 3 x 10(2) Pa, respectively, were studied using X-ray photoelectron spectroscopy. The formation of surface sulfite at T greater than or equal to 473 K (the S 2p(3/2) binding energy (E-b) is 167.5 eV) and surface sulfate at T greater than or equal to 573 K (E-b = 169.2 eV) was observed in the reactions of Al2O3 and CeO2 with SO2. The formation of sulfates on the surface of CeO2 occurred much more effectively than in the case of Al2O3, and it was accompanied by the reduction of Ce(IV) to Ce(III). The formation of aluminum and cerium sulfates and sulfites on model Pt/Al2O3 and Pt/CeO2 catalysts occurred simultaneously with the formation of surface platinum sulfides (E-b of S 2p(3/2) is 162.2 eV). The effects of oxygen and water vapor on the nature and yield of sulfur-containing products were studied.