Catalytic Aqueous Phase Conversion of Polyols to Hydrogen and Chemicals

The present work is focused on the study of aqueous phase reforming reaction (APR), its mechanism and the relation within catalyst activity and metal/support properties. Several oxides and mixed oxides were studied, synthesized by traditional co-precipitation technique and microemulsion. The first focus was the upgrading of glycerol mainly towards the optimization of the system with different catalysts and the relation with the reaction mechanism. Heated ATR-IR technique was developed to perform in-situ tests to elucidate the formation of reaction intermediates and confirm the mechanism hypothesis with different catalysts. In terms of catalytic performances, interesting results were obtained with Pt/TiO2 catalyst with the support prepared by water in oil microemulsion technique. Improved performances have been demonstrated in comparison with Pt over commercial TiO2 support, attributing the effect to the synergy between metal and support. Moreover, it was studied and elucidated the effect of basic and acid sites in Pt-loaded Mg/Al supports. Similarly, the role of addition of redox metals as Ni and Fe in enhancing hydrogen production or liquid phase products was also determined. The interesting results obtained with glycerol allowed shifting towards a more complex polyol as glucose, studying the reactivity previously defined with degradation and isomerization reactions typical of this molecule. Beside the optimization of reaction parameters using Pt/TiO2-m catalyst, the effect over products distribution of the acid/base support features and type of metal was studied and the relation structure/reactivity based on catalyst characterization. The most interesting non noble metals tested have been used to synthesize bimetallic bulk catalyst with interesting properties even with respect to Pt reference metal.