Simultaneous operation of dibenzothiophene hydrodesulfurization and methanol reforming reactions over Pd promoted alumina based catalysts

In the current study simultaneous reactions of hydrodesulfurization (HDS) of dibenzothiophene (DBT) and reforming of methanol in a micro-autoclave reactor were studied over bi-metallic (Co-Mo/Al₂O₃ and Ni-Mo/Al₂O₃) and tri-metallic (Pd-Co-Mo/Al₂O₃ and Pd-Ni-Mo/Al₂O₃) catalyst systems which were prepared by incipient impregnation method. In situ hydrogen utilization and low Pd loadings were the major targets of this study. For comparison purpose, catalytic activity was separately determined for both the methanol reforming and HDS of DBT reactions as well. Ni based catalysts were confirmed with better activity than Co ones for both the reactions with Pd promoted ones ranking at the top i.e. Pd-Ni-Mo/Al₂O₃ > Ni-Mo/Al₂O₃ > Pd-Co-Mo/Al₂O₃ > Co-Mo/Al₂O₃ where Pd-Ni-Mo/Al₂O₃ showed 91% DBT conversion at 380°C and 12 h reaction time. Some of the selected organic additives on catalytic activity were tested for their effect toward HDS reaction which was unique with close relation to their chemical nature. Reaction products were quantitatively and qualitatively analyzed via HPLC and GC-MS techniques respectively which helped in elucidating reaction mechanism.