Selective catalytic oxidation of H2S to elemental sulfur over titanium based Ti-Fe, Ti-Cr and Ti-Zr catalysts

In this study, titanium oxide catalyst was incorporated with iron, chromium and zirconium to improve catalytic activity for selective catalytic oxidation of H2S to elemental sulfur. Equimolar titanium based iron (Ti-Fe), chromium (Ti-Cr) and zirconium (Ti-Zr) catalysts were synthesized by the complexation method and tested in oxidation between the temperature range of 200-300 °C and using different O2/H2S ratios. Ti-Fe catalyst with Fe2TiO5 crystalline phase and Ti-Cr catalyst with mainly Cr2O3 crystalline phase showed complete conversion of H2S and high sulfur selectivity (close to one) at 250 °C. Ti-Zr catalyst having relatively high surface and small pore diameter could not prevent sulfur deposition on the surface and lost in catalytic activity at the same temperature. Ti-Fe catalyst had high activity with 100% conversion and sulfur selectivity in the reaction period of an experimental run (150 min) even at lower oxidation temperature (200 °C). It was concluded that incorporation of iron into Ti-Fe catalyst structure improved the redox ability and surface acidity of the catalyst. Fe2TiO5 mixed metal oxide in the Ti-Fe catalyst was responsible and active phase resulting in complete conversion of H2S and high sulfur selectivity in the selective oxidation of H2S to elemental sulfur.