Macroporous Supported Cu–V Oxide as a Promising Substitute of the Pt Catalyst for Sulfuric Acid Decomposition in Solar Thermochemical Hydrogen Production

The macroporous supported Cu–V oxide prepared by a novel dissolution–reprecipitation process was found to be the first example of a promising substitute of Pt catalysts for sulfuric acid decomposition at moderate temperatures (∼600 °C), which is required in solar thermochemical hydrogen production. Stepwise impregnation of Cu(NO 3 ) 2 and NH 4 VO 3 onto 3-D ordered mesoporous SiO 2, and subsequent heating at 650 °C yielded the deposition of copper pyrovanadate (Cu 2 V 2 O 7, melting point: 780 °C) not only in mesopores but also on the external surface. Thermal aging at 800 °C caused the congruent melting of Cu 2 V 2 O 7 followed by smooth penetration of the melt into mesopores and homogeneous covering of cavity walls. Because of the solubility of SiO 2 into the molten vanadate, dissolution–reprecipitation should be equilibrated to allow substantial structural conversion from mesoporous to macroporous SiO 2 frameworks. The resulting macroporous catalyst consisting of highly dispersed thin layers of active Cu 2 V 2 O 7 is considered efficient for catalytic reactions and the mass transfer of reactants and products in the presence of high-concentration vapors.