COMPARISON BETWEEN THERMAL-DECOMPOSITION AND PHOTOSPLITTING OF H2S OVER VXSY SUPPORTED ON OXIDES AT 450-DEGREES-C-550-DEGREES-C IN A STATIC SYSTEM

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 H2S was carried out in a cylindrical photothermal furnace using vanadium sulfide on Al2O3. TiO2, 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 VxSy/ZnS, while the photoactivation of the catalyst increases the conversion of H2S up to 40% depending on the temperature and supporting materials of VxSy. 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 H2S to hydrogen is the enhancing reaction by direct action of solar radiation.