(771d) Fundamental Understanding of the Surface Structures of Bimetallic Catalysts for Aqueous-Phase Reforming of Glycerol

Aqueous-phase processing of biomass and its derived chemicals has become a hot research topic for its application in fuel generation. Reforming of polyols in aqueous phase is one of the techniques developed within this scope and targeted at producing hydrogen as the renewable energy source. Much effort has been devoted in catalyst (including bimetallics) development for better performance. However, the surface changes of the catalyst encountered during the reaction are not very well understood. In this work, we studied the surface structure and chemistry of Pt/C and Pt-Re/C under a series of different environments that the catalysts may be exposed to for the process of aqueous-phase reforming of glycerol. Re was found to enhance the catalytic activity of Pt/C for this reaction and a previous explanation was the weakened CO interaction with catalyst surface due to PtRe alloy formation. However, our investigation indicates that with the PtRe alloy on the catalyst surface, CO adsorption can be stronger than that over Pt/C while giving rise to a much higher activity. With the in situ spectroscopic characterization tools, we were able to ascribe the enhanced activity to both the Pt surface modified by Re through charge transfer and the extra surface acidity introduced by the interaction between water and Pt-Re entities. Moreover, the selectivity was also greatly affected by the in situ generated surface acidity through a dehydration pathway.