• Does sulphiding of hydrotreater CoMo and NiMo catalyst possible with Straight run feed containing Sulphur instead of DMDS?

    If so, how exactly Sulphur containing Straight run feed can sulfide the catalyst?

    As in the later case, DMDS decompose at the operating temperature of above 190degC and provides required H2S for initiation of sulphiding process, but how does Sulphur containing straight run feed can provide H2S?



  • Nasir Hussain, Pak Arab, nasir.hussain@parco.com.pk

    Another reason for not using the Straight run diesel for sulding is that it will take too much time to complete the sulfiding. Previous answer is also accurate because as the temperature of the catalyst is increased and we do not have sufficient H2S then the catalyst can be converted to reduced form which is the permanent deactivation. Further, the quantity of sulfding agent can easily be manipulated as per requirement and giving the control on sulfding.



  • Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br

    This is not recommended once the sulfiding process requires an adequate concentration of sulphur capable to promote the conversion of metal oxides into metal sulphides which is the active phase of the hydrotreating catalysts. It's difficult to ensure and control the concentration of sulphur in the catalytic bed with only the available sulphur in the feed, this can lead to the permanent deactivation of the catalyst due to the metal reduction.

    By this reason the sulfiding process applying a sulfiding agent (DMDS or TBPS, for example) with carefully controlled procedure, especially related to the temperature control. The sulphur is heated in the presence of hydrogen generating H2S which is able to carry out the sulfiding reactions of the catalyst metals and generating the active phases (MoS2, CoS, NiS, and WS2).


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