Study of poisoning effect of dimethyl disulfide on Ni/Al₂O₃ catalyst for hydrogenation

Poisoning effect of dimethyl disulfide (CH₃SSCH₃) on Ni/Al₂O₃ catalysts for hydrogenation of benzene, cyclohexene and styrene was studied. The structures and properties of the catalysts were investigated by means of BET, XRD, H₂-TPR, XPS, SEM and EA. Results indicated that with the existence of CH₃SSCH₃, Ni/Al₂O₃ catalysts quickly deactivated for benzene and cyclohexene hydrogenation, while the activity for styrene hydrogenation remained well. The sulfur tolerance of Ni/Al₂O₃ catalysts for cyclohexene hydrogenation was little better than that of benzene hydrogenation. The conversion of conjugated double bond of styrene can keep 100% for a long time. For hydrogenation reactions, the poisoning effects of CH₃SSCH₃ over Ni/Al₂O₃ were in the order of aromatic nucleus>monoene>conjugated alkene. In addition, poisoning mechanism of CH₃SSCH₃ for Ni/Al₂O₃ catalyst was also discussed. CH₃SSCH₃ molecules were firstly adsorbed on the surface of catalyst and then dissociated to CH₄ under the function of hydrogen and catalyst. It is concluded that the toxicity of carbon in CH₃SSCH₃ for catalysts is neglectful and remaining sulfur is the dominant poisoning factor by the interaction with active component.