Selective oxidation of H2S in Claus tail-gas over SiC supported NiS2 catalyst

Very high activity and selectivity could be achieved for the direct oxidation of H2S into elemental sulfur at low reaction temperature (40-60 degrees C), on nickel sulfide supported SiC catalyst. The heterogeneous nature of the support surface (hydrophilic and hydrophobic areas) could explain the important role played by water to maintain a high and stable H2S conversion level. The formation of a very active superficial nickel oxysulfide phase was proposed in order to explain the activation period necessary at reaction temperatures <60 degrees C. Total selectivity for sulfur was attributed to the very low reaction temperature and the absence of any microporosity in the support. (C) 2000 Elsevier Science B.V. All rights reserved.