Comparison between thermal decomposition and photosplitting of H 2S over V xS y supported on oxides at 450–550°C in a static system

Abstract

Hydrogen sulfide is present in sour gas wells or produced in hydrodesulfurization of high sulfur fossil fuels. The recovery of hydrogen in addition to elemental sulfur could become a very important industrial process with economic and environmental advantages. Thermal decomposition and photosplitting of H 2S was carried out in a cylindrical photothermal furnace using vanadium sulfide on Al 2O 3, TiO 2, ZnO and ZnS as catalyst. A 30 ml pyrex glass reaction vessel, with light flux of 130 mW cm −2 has been studied in a static system. The conversion increased to more than 7.5% in the case of V x S y /ZnS, while the photoactivation of the catalyst increases the conversion of H 2S up to 40% depending on the temperature and supporting materials of V x S y . Absorption of photons by these catalysts at high temperature has been considered assuming that the molecules change to their excited states and photoproduce electrons and holes at the surface. The mechanism for splitting of H 2S to hydrogen is the enhancing reaction by direct action of solar radiation.