Conversion of thiophene on molybdena–alumina catalysts containing Group 8–10 metals: effect of H2S uptake

Abstract

Ageing and the effect of H₂S on the activity and selectivity of Co-, Ru-, Pd-, Ir-and Pt-promoted and unpromoted MoO_x–Al₂O₃ catalysts have been studied in relation to decomposition of thiophene. The overall activity increased on unpromoted and Pd-promoted molybdena–alumina, whereas on other catalysts it decreased substantially. The selectivity of production of butane and of fragmented hydrocarbons decreased on all catalysts. The changes in catalytic behaviour were caused by the uptake of H₂S added to the system and produced in hydrodesulfurization (HDS) of thiophene. The results indicate no direct correlation between the propensity to interact with H₂S and the HDS activity. It follows from data on changes in selectivity, that metal and molybdena act predominantly independently at the early stages of sulfidation.