Rhodium-catalyzed partial oxidation of methane to CO and H2. In situ DRIFTS studies on surface intermediates

Reaction steps in the oxidation of CH₄ to CO and H₂ over a Rh(1 wt%)/-Al₂O₃ catalyst were studied using in situ DRIFTS at 973 K and 0.1 MPa. Product distribution and the resulting absorption band intensities of the respective adsorbates were strongly influenced by oxygen coverage and carbon deposits on the surface. CH₄ is dehydrogenated to carbon deposits and H₂ and is simultaneously oxidized to CO₂ and H₂O. OH surface groups in the support are involved in the CH_x conversion to CO via reforming reaction. The reaction of surface carbon with CO₂ was assumed to contribute to CO formation. Formate is a by-product of the reaction.