Structure and SO3 decomposition activity of CeVO4/SiO2 catalysts for solar thermochemical water splitting cycles

Abstract Ce–V oxide catalysts supported on bimodal mesoporous SiO 2 were prepared by a wet impregnation method to study their catalytic activity for SO 3 decomposition, which is a key step in thermochemical water splitting cycles based on the sulfur–iodine process. As-prepared Ce–V/SiO 2 catalysts exhibited more than 50-fold higher turnover frequency at 600 °C compared to unsupported CeVO 4 . This is in accordance with the smaller size (13 nm) of CeVO 4 particles highly dispersed in SiO 2 mesopores, compared to approximately 600 nm for unsupported CeVO 4 particles. The Ce–V/SiO 2 catalysts exhibited a higher activity than supported V 2 O 5 or CeO 2 catalysts, which coexisted depending on the Ce/V ratio. Among the studied catalysts with different Ce/V molar ratios, the highest activity was achieved at Ce/V = 0.9, at which the greatest specific surface area of CeVO 4 was attained. The catalyst demonstrated SO 3 decomposition rates comparable to those of Pt/Al 2 O 3 in a wide range of WHSV (3.6–110 g-H 2 SO 4  g −1  h −1 ) and no indication of noticeable deactivation during 40 h of the catalytic reaction at 650 °C.