Doping Transition Metals into TiO₂‐CNT Nanocatalyst to Enhance the Selective Oxidation of H₂S

Abstract

In this research work, the transition metals (Ni, Co and W) have been doped into the TiO 2-CNT (X-TC) nanocatalysts through sol-gel method. The structure and composition of the synthesized catalysts were determined by various qualitative and quantitative techniques. Their performance was evaluated in selective oxidation of H 2 S to elemental sulfur and compared to those of the undoped TiO 2-CNT (TC). It was found that the all metals which were doped into the TC catalyst showed much better desulfurization performance than the TC. The H 2 S conversion of the catalysts followed the trend of Co5 %-TC > Ni5 %-TC > W5 %-TC ∼ TC and Co10 %-TC > Ni10 %-TC > W10 %-TC ∼ TC and the selectivity was almost higher than 99 % in all catalysts. In this regard, the 5 %Co-TC had the higher H 2 S conversion of 99.5 %, sulfur selectivity of 99.6 % and sulfur yield of 99.1 % which is attributed to the lower band gap and higher specific surface area and pore volume in comparison to the other metal-doped TC catalysts. In addition, the increase in the metal content to 10 wt. % decreased the H 2 S conversion and sulfur selectivity because the metal particles on TC deteriorated the surface area and pore volume of the catalysts. The high catalytic activity of metals doped catalysts can be attributed to doping active transition metals as active site on mesoporous support of TC.