The refinement of the rate determining process in sulfur trioxide electrolysis using the electrolysis cell

Clarification of the Mechanism of Sulfur Trioxide Electrolysis—Evaluation of SO3and O Atom Adsorbed on Pt Surface—

“…We showed that the rate-determining process in SO 3 electrolysis depends not on the conductivity of O 2À through YSZ electrolyte, but rather on the electrode reaction by using the electrolysis cell composed of YSZ electrolyte and Pt electrode. 2) This study indicated that it is necessary to enhance SO 3 pressure or temperature in order to enhance the SO 3 electrolysis rate. 2) However, it is difficult to enhance the temperature because FBR cannot supply heat above 550 C. Under the conditions of SO 3 pressure above 0.1 atm and temperature below 500 C, the rate-determining process of SO 3 electrolysis is assumed to be SO 3 adsorption and dissociation reaction on the electrode for the SO 3 electrolysis in our previous study.…”

“…We analyzed the SO 3 electrolysis experiment on the assumption that SO 2 is desorbed directly from SO 3 adsorbed on the electrode. 2) It is necessary to investigate this assumption. In configuration A, the overlap population between the S and O atoms bound to the Pt atom is larger than that between this O and the Pt atom.…”

“…2) However, it is difficult to enhance the temperature because FBR cannot supply heat above 550 C. Under the conditions of SO 3 pressure above 0.1 atm and temperature below 500 C, the rate-determining process of SO 3 electrolysis is assumed to be SO 3 adsorption and dissociation reaction on the electrode for the SO 3 electrolysis in our previous study. 2) Recently, the SO 3 configuration on the Pt surface was investigated by the theoretical method. 3) This investigation was not performed in much detail.…”

Sulfur trioxide electrolysis studies: Implications for the sulfur–iodine thermochemical cycle for hydrogen production

“…Due to Le Chatlier's principle, the SO 3 to SO 2 conversion reaction reaches an equilibrium point that inhibits the conversion of 100% of the SO 3 to SO 2 . The conversion fraction rises as temperature increases [11]; at 1 atm of pressure, a temperature of 1250 C is required for near complete conversion [7]. Additionally, the temperature required for complete SO 3 conversion rises as pressure is increased [12].…”

“…The electrolysis rates, and thus efficiencies, of cells such as those used in the JAEA feasibility experiments would be limited by the low flux of oxygen ions through the tubular cells' thick electrolyte layer and by the poor performance of the platinum electrodes, which lack oxygen ion conductivity [7].…”