Production of elemental sulfur and ammonium thiosulfate by H2S oxidation over Nb2O5 supported on Fe-pillared clay

The catalytic oxidation of hydrogen sulfide (H2S) in the presence of ammonia was studied over niobium pentoxide supported on Fe-pillared clay catalysts (Nb/Fe-PILCs). The synthesized catalysts were characterized by various techniques such as X-ray diffraction, BET method, X-ray photoelectron spectroscopy, temperature-programmed reduction, temperature-programmed desorption of ammonia, and transmission electron microscopy. Catalytic performance studies of the Nb/Fe-PILC catalysts showed that H2S was successfully converted to elemental sulfur and ammonium thiosulfate without any considerable emission of sulfur dioxide. The results show that 3 wt% Nb/Fe-PILC exhibited the highest H2S conversion, which might be due to the uniform dispersion of niobium-oxide species on the Fe-PILC support. Niobium on the fresh Nb/Fe-PILC catalyst was in the +5 oxidation state and it was partially reduced to a lower oxidation state after the reaction.