Hydrothermal synthesis of CuV2O6 supported on mesoporous SiO2 as SO3 decomposition catalysts for solar thermochemical hydrogen production

Hydrothermal synthesis of CuV2O6 supported on 3-D ordered mesoporous SiO2 (CuV/SiO2) was studied to evaluate the catalytic activity for SO3 decomposition, which is a key step in solar thermochemical hydrogen production. A composite oxide hydrate, Cu3O(V2O7)·H2O, and an oxide hydroxide hydrate, Cu3(OH)2V2O7·(H2O)2, were formed at lower hydrothermal temperatures (≤200 °C). The oxide hydrate phase mainly yielded Cu2V2O7 after calcination at 600 °C in air. By contrast, the hydrothermal synthesis at 250 °C (CuV/SiO2@250) directly crystallized CuV2O6 from the oxide hydroxide hydrate, although its very large particle size (∼5 μm) is not suitable for the catalytic application. The SO3 decomposition activity measured at 600 °C was associated with the yield as well as the dispersion of CuV2O6, giving rise to the maximum for the hydrothermal synthesis at 200 °C. CuV/SiO2@250 achieved the highest catalytic activity at the reaction temperature of 650 °C, because the melting phase of CuV2O6 penetrated mesoporous SiO2 and thus improved the dispersion of the active phase.