Surface analysis of sulfided dispersed metal catalysts

Abstract A Ni–Cr/MgSiO 3 catalyst retained appreciable methanation activity after a pre‐sulfiding treatment in comparison with Ni/MgSiO 3 catalyst. Surface analysis by X‐ray photoelectron spectroscopy of pre‐sulfided catalysts that have been treated in various ways has shown that the Ni–Cr/MgSiO 3 catalyst retains less total sulfur and that the sulfur retained is in the form of both sulfide and sulfate. In the Ni/MgSiO 3 catalyst, sulfur is found only in the sulfide form. It is proposed that the presence of Cr (as Cr 2 O 3 ) promotes the formation of sulfate which deactivates the catalyst to a lesser extent due to the instability of the sulfate ion at the methanation reaction temperature.