(455f) Reforming of Glycerol Over Pt/C and Pt-Re/C in Aqueous Phase: Understanding Catalyst Function and Reaction Pathways for Hydrogen Production

Zhang, L. - Presenter, Pacific Northwest National Lab
Karim, A. - Presenter, Pacific Northwest National Lab
King, D. L. - Presenter, Pacific Northwest National Lab
Wang, Y. - Presenter, Pacific Northwest National Laboratory

Study of bioliquid reforming in aqueous phase is of increasing interest due to its potential application in fuel cells powered by renewable sources. Pt and Re-promoted Pt are considered promising catalysts for the catalytic process occurring at the liquid-solid interface. Despite the encouraging progress in demonstrating high hydrogen selectivity achieved on Pt or high conversion obtained on Pt-Re, fundamental understanding of the catalyst function under working conditions and its effect on reaction pathways is not complete. For this reason, we have studied structures of the catalysts by in-situ characterization techniques and identified a dual-functionality of Pt-Re under hydrothermal conditions: modification of Pt electronic structure through charge transfer and formation of ReOx. Our kinetic study suggests that the main reaction pathways occurring over Pt/C is through dehydrogenation of polyols followed by cleaving C-C bond of aldehyde intermediates. Addition of Re increases conversion of glycerol, but the ReOx formed in APR process also provide acidity to facilitate C-O scission through dehydration pathway competing with C-C breaking pathway. Because C-O scission followed by hydrogenation consumes hydrogen generated by C-C cleavage, the hydrogen selectivity decreases with addition of Re. However, with the conversion enhancement by Re addition, hydrogen TOF could be maximized by controlling Pt/Re ratio. In addition, effect of addition of base and reaction conditions on the reaction pathways will be discussed in order to optimize hydrogen production.