Performance and Postreaction Characterization of γ-Mo2N Catalysts in Simultaneous Hydrodesulfurization and Hydrodenitrogenation Reactions

An unsupported γ-Mo2N catalyst was prepared to perform simultaneous HDS of benzothiophene and HDN of indole, as well as HDS in the presence/absence of NH3and HDN in the presence/absence of H2S. Pre- and postreaction catalysts were characterized using XPS, TPD, TPR, XRD, and BET techniques. While ethylbenzene was the only major hydrocarbon product from benzothiophene HDS throughout the temperature range tested (200–380°C), C6–C8alkylbenzenes and alkylcyclohexanes were observed from indole HDN. The presence of sulfur compounds changed the products of indole HDN from primarily aromatics to cyclohexanes. In the presence of sulfur compounds, the product distribution from indole reaction over the Mo nitride catalysts was similar to that over a sulfided Mo/γ-Al2O3catalyst. Postreaction XPS measurements showed a pronounced decrease in N content and the presence of MoS2over the Mo nitride surface. The findings of this study suggest that the bulk of the postreaction Mo nitride catalyst was still in the Mo2N structure and that it acted as a support for the MoS2phase, which in turn, controlled the catalytic performance.