The Effect of Support on Sulphur Tolerance of Rh Based Catalysts for Methane Partial Oxidation

Abstract

The presence of sulphur containing compounds, naturally occurring in natural gas or added as odorants, can adversely affect the performance of noble metals based catalysts for the partial oxidation of methane to syngas. In this paper the effect of SO₂ addition on the catalytic partial oxidation of methane was investigated on Rh (1 wt.%) catalysts prepared by incipient wetness impregnation method on two different commercially available high temperature γ-alumina supports stabilized either with 10% SiO₂ or 3% La₂O₃. Based on the results of catalytic activity measurements and in-situ FT-IR spectroscopic characterisation, as well as TPR/TPD studies, it has been shown that the presence of sulphur can severely suppress the formation of synthesis gas by inhibiting the reforming reactions during the catalytic partial oxidation of methane. The results also demonstrated that the support plays a crucial role in the partial oxidation reaction. In the presence of a sulphating support such as La₂O₃–Al₂O₃ the partial oxidation reaction was much less inhibited than a less sulphating support such as SiO₂–Al₂O₃. The sulphating support acts as a sulphur storage reservoir, which minimises the poison from adsorbing on or near the active Rh sites where reactions take place.