Clarification of the Mechanism of Sulfur Trioxide Electrolysis —Evaluation of SO3 and O Atom Adsorbed on Pt Surface—

Abstract

We developed a hybrid thermo-chemical process, which included a SO3 electrolysisprocess utilizing the heat supplied by a fast breeder reactor (FBR), as a new hydrogen production process. To clarify the mechanism of SO3 electrolysis, we evaluated the electronic states of SO3 and O atom adsorbed on the Pt (111) surface using first-principles calculations with a slab model. Moreover, we evaluated the chemical bonding states of SO3 and adsorbed O using molecular orbital calculation on the basis of the calculations using a slab model. We found that there were two stable adsorbed SO3 configurations on the Pt surface. From the molecular orbital calculation, it was found that the S-O bond became weak by SO3 absorption, and it was conjectured that SO3 dissociation proceededthrough the intermediate state of adsorbed SO2 and adsorbed O on the Pt surface. Moreover, we derived the O coverage considering the adsorbed SO2 and evaluated the influence of SO3 adsorption energy on the O coverage.