Selective oxidation of H2S to elemental sulfur over TiO2/SiO2 catalysts

Selective catalytic oxidation of H2S to elemental sulfur using TiO2/SiO2 catalysts was investigated in this study. The reaction test with pure TiS2 and Ti(SO4)(2) and cyclic temperature operation showed that TiO2 had good resistance to sulfation and sulfidation, which are known as the main causes of catalytic deactivation in sulfur recovery process. Catalyst deactivation caused by deposition of sulfur on the catalyst surface resulted in a decrease in the conversion of H2S, not in the selectivity to sulfur, at low reaction temperatures. With an increase in the O-2/H2S ratio from 0.5 to 4, the conversion was slightly increased, but the selectivity to elemental sulfur was remarkably decreased. The presence of water vapor decreased both the activity and selectivity. Temperature programmed desorption with NH3 and CH3COOH and reaction tests after doping K2O and B2O3 to TiO2/SiO2 revealed that the selective oxidation of H2S occurred on acidic sites and the reverse Claus reaction proceeded on basic sites. (C) 1998 Elsevier Science B.V.