Investigation of 4,6-dimethyldibenzothiophene hydrodesulfurization over a highly active bulk MoS2 catalyst

The hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene was investigated in a batch-stirred microautoclave reactor over a laboratory-synthesized MoS2 catalyst. The reaction was found to proceed through two main parallel pathways: direct desulfurization (IDDS) and hydrogenation (HYD). The effect of a wide range of H2S concentrations on the HDS activity and selectivity was studied. Contrary to the well-known inhibition of HDS caused by H2S, the global catalytic activity of HDS was enhanced more than two times with inclusion of H2S in the reaction zone. The increase in the activity is attributed to a significant enhancement in the hydrogenation reaction route, while the direct desulfurization products were only slightly affected. It is suggested that H2S modifies the active sites so that they can be exploited more efficiently in the hydrogenation reaction. (C) 2004 Elsevier Inc. All rights reserved.