Chemical Looping Selective Oxidation of H2S using V2O5 Impregnated over Different Supports as Oxygen Carriers

Chemical looping concept is proposed to improve the efficiency of selective oxidation of H2S into elemental sulfur. V2O5 as an active oxygen carrier, is impregnated on different supports and exposed cyclically to reductant (H2S) and to oxidant (O-2). Among all, TiO2 and SiO2 proved as better supports for V2O5 as they provided more formation of elemental sulfur than undesired SO2 in the reductant step. Results indicate that the support can either directly react and provide oxygen to the process like for CeO2 or indirectly affect the properties of the active phase, leading either into the improvement, as for TiO2 and SiO2, or worsening, as in case of Al2O3 and ZrO2. Oxygen carriers with partially reduced species, i. e., the combination of V5+ and V4+, show better performances than carriers containing mostly highly oxidized V5+ species. Interaction between the active phase and support plays a vital role for the controls of the formation of these partially reduced species.