Elucidation of the roles of Re in steam reforming of glycerol over Pt-Re/C catalysts

In this paper, we report the fundamental surface properties of Pt/C and Pt-Re/C catalysts and their correlation with catalytic performance in steam reforming of glycerol. We found that the addition of Re increases the catalytic activity, H-2/COx, ratio, and CO2 selectivity. N-2 physisorption, CO chemisorption, and attenuated total reflectance infrared (ATR-IR), Raman, and X-ray absorption spectroscopy (XAS) with in situ capabilities were employed to provide insight into the roles of Re. Using ATR-IR, we show that CO adsorption on reduced Pt-Re/C is stronger than on Pt/C. However, CO desorption from Pt-Re/C is much facilitated compared with that from Pt/C after steam pretreatment, which is more representative of the steam reforming conditions. In situ Raman and XAS studies suggest that oxidized rhenium species are formed in steam environments on the Pt-Re/C catalyst surface. The spillover of CO from neighboring Pt to such oxidized rhenium is likely the reason for the facile desorption of CO, which could further react to form CO2. Such facile CO desorption leads to enhanced glycerol steam reforming and water-gas shift activities over the Pt-Re/C catalyst. (C) 2014 Elsevier Inc. All rights reserved.