Metal oxide/TiO2 nanocomposites as efficient adsorbents for relatively high temperature H2S removal

Abstract

Hydrogen sulfide is a highly toxic and corrosive gas that is present in different environments such as hot coal gases. In order to have a clean atmosphere and prolong the life of industrial equipment and metallic catalysts, it is necessary to remove or decrease the concentration of this gas in feedstocks to sub parts per million before their use. To accomplish this task, various nanocomposite sorbents were studied for H2S removal at relatively high temperature. To this end, the NiO/TiO2, CuO/TiO2, and CoO/TiO2 nanocomposites were prepared through wet impregnation. X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) equipped with Energy-dispersive X-ray spectroscopy (EDS) and N2 adsorption/desorption were used for characterizing the prepared nano sorbents. The H2S adsorption reaction experiments were performed at relatively high temperature and effects of the promoter to TiO2 ratio, sorbent mass and desulfurization temperature were studied. The results showed that at 480 °C, the CoO promoted TiO2 shows longer breakthrough time followed by NiO/TiO2 and CuO/TiO2 sorbents. The best results were obtained by using the promoter to TiO2 ratio of 2.5/5 among the ratios used. By decreasing the temperature and performing the experiments at 400 °C, the nickel oxide promoted TiO2 showed better results than the CoO/TiO2 suggesting the lower sulfidation activity of CoO promoter at this temperature.