In this work, the reforming of model biogas was investigated on a Rh/MgAl O catalyst. In situ transient and steady-state diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements were used to gain insight into the reaction mechanism involved in the activation of CH and CO . It was found that the reaction proceeds through of an initial pathway in which methane and CO are both dissociated on Rh metallic sites and additionally a bifunctional mechanism in which methane is activated on Rh sites and CO is activated on the basic sites of the support surface via a formate intermediate by H-assisted CO decomposition. Moreover, this plausible mechanism is able to explain why the observed apparent activation energy of CO is much lower than that of CH . Our results suggest that CO dissociation facilitates CH activation, because the oxygen-adsorbed species formed in the decomposition of CO are capable of reacting with the CH species derived from methane decomposition.

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The present paper addresses the nature of the active sites of a bimetallic Ni-Ru supported catalyst on the dry reforming of methane (DRM). The structural characterization by XRD and Raman spectroscopy, along with the reducibility study (TPR-H2) of the samples, evidenced the existence of a strong Ni-Ru interaction in the bimetallic system. We have assumed that Ru atoms block the most reactive Ni sites (step-edge sites) leaving less reactive centers for methane activation (terraces). In this way, operando DRIFTS measurements revealed that Ru decreases the catalytic activity but favors the carbon gasification and prevents the CO dissociation.

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