Formation of cereous sulphate phase upon interaction of SO_2 with ceria at room temperature Thermal analysis, Raman and EPR study

摘要

The adsorption of SO_2 gas on ceria solid at room temperature has been investigated by thermal analysis, Raman spectroscopy and electron paramagnetic resonance (EPR). The results confirm that SO_2 transformation into sulphate species occurs at 25 ℃ with a concomitant reduction of Ce~(4+) to Ce~(3+) ions. The formation of Ce(III)-sulphate phase has been evidenced on ceria surface. The thermal analysis revealed a complete decomposition of cereous sulphate phase to CeO_2 at 785 ℃. The change of oxidation state of Ce(IV) to Ce(III) during the formation of sulphate phase has been confirmed also by EPR technique.