Selective catalytic oxidation of H2S over Fe2O3 /TiO2 catalysts

Fe2 O3 / TiO2 catalysts were prepared by sol⁃gel method. The physicochemical properties of catalysts were characterized by BET，XRD and XRF，and the activity of catalysts for the selective catalytic oxidation of H2 S was investigated by the fixed⁃bed reaction system. The results show that the specific surface area of the catalyst gradually increases with the increase of loading，and the Fe2 O3 exists uniformly in the catalyst phase in highly dispersed or amor⁃ phous form when the Fe2O3 loading is less than 15%. When the Fe2O3 loading continues to increase to 20%，the spe⁃ cific surface area of the catalysts decreases，the Fe2 O3 exists in the form of crystal and blocks the pore structure of the catalyst surface. With the increase of loading，the H2 S conversion and sulfur yield of Fe2 O3 / TiO2 increase at first and then decrease，while the sulfur selectivity decreases，the 15 % Fe2 O3 / TiO2 catalysts perform well under the condi⁃ tions of reaction temperature 180 °C and the O2 / H2 S molar ratio 0. 5. The H2 S conversion rate，sulfur selectivity and sulfur yield are 96. 57%， 95. 88% and 92. 60%， respectively. The reaction temperature and the molar ratio of O2 / H2 S have great influence on the activity of the catalysts. With the increase of reaction temperature，the H2 S conver⁃ sion rate increases at first and then decreases， while the sulfur selectivity and sulfur yield decrease continuously. With the increase of O2 / H2 S molar ratio，the H2 S conversion rate increases and the sulfur selectivity de⁃ creases gradually，and the sulfur yield increases at first and then decreases，and the sulfur yield is the highest when the O2 / H2 S molar ratio is 0. 5. The analysis of spent catalysts show that elemental sulfur and sulfate are the main product of the catalytic oxidation of H2 S. In addition，the possible catalytic oxidation mechanism of H2 S on the Fe2 O3 / TiO2 catalysts is proposed，in which Fe3+ is the main active component and plays a major role in the selective catalytic oxidation of H2 S. The formation of ferric sulfate and deposition of elemental sulfur are the main reasons for the deacti⁃ vation of the catalysts.