Effects of concentration and microstructure of active phases on the selective hydrodesulfurization performance of sulfided CoMo/Al2O3 catalysts

•The concentration and microstructure of active phases in CoMo catalysts were tuned.•CoMoS phases account for the hydrodesulfurization reaction.•MoS2 phases account for the olefin hydrogenation reaction.•The thiophene HDS reaction occurs primarily at the edge of CoMoS active phases.•The olefin hydrogenation reaction occurs mainly at the corner of MoS2 active phases.

This investigation offers new understanding regarding the nature of CoMoS and MoS2 active phases coexisting on sulfided CoMo/Al2O3 catalysts for the selective hydrodesulfurization (HDS) of gasoline. Two series of the CoMo/Al2O3 catalysts with different ethylenediaminetetraacetic acid (EDTA)/Co molar ratios and the EDTA-containing CoMo/Al2O3 catalysts with different cobalt contents were prepared, and the properties of their active metal phases were systematically correlated with their HDS selectivities. It was found that a high concentration of CoMoS phases improves the HDS activity of the sulfided CoMo/Al2O3 catalysts but that a high concentration of MoS2 phases enhances the olefin hydrogenation (OHYD) activity of these catalysts. From the perspective of microstructure, it was evident that the thiophene HDS reaction occurs primarily at the edge of CoMoS active phases and that the OHYD reaction occurs mainly at the corner of MoS2 active phases. These understandings shed light on the development of highly selective HDS catalysts.

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