Integrated sol-gel and hydrothermal synthesis of V2O5–TiO2 nanocatalysts for enhanced catalytic removal of H2S

Abstract

Hydrogen sulfide (H2S) emitted from the petroleum refinery process, landfills, or biogas purification is severely corrosive and has harmful health effects on the human body when inhaled at even small concentrations. Selective catalytic oxidation using V2O5–TiO2 is considered to be a benchmark technology for removing H2S. This paper presents a novel preparation method to synthesize V2O5–TiO2 nanocatalysts to improve desulfurization performance. Compared with the conventional sol-gel or wet-impregnation method, the integrated sol-gel and hydrothermal synthesis allows for a substantial increase in the specific surface area, which is mainly attributed to the highly reduced sizes of the primary particles. The enhanced surface area contributes to effective dispersion of the vanadium (V) species on the TiO2 support, by which the interactions between V and titanium (Ti) are strengthened. Accordingly, the redox properties of the catalysts are improved with increased concentrations of the chemisorbed oxygen species on the catalyst surfaces. Finally, the properties of the V2O5–TiO2 nanocatalysts are improved by the new preparation conditions, resulting in significantly enhanced catalytic activities in the selective oxidation of H2S: the best catalyst exhibits excellent activity even at 50 °C. It was also observed that the temperature during the hydrothermal reaction severely affected the catalytic performance of the V2O5–TiO2 nanocatalysts. This study suggests the importance of the preparation conditions for manipulating the physicochemical properties and performances of catalysts.