Investigation of Aqueous Phase Reforming reaction of xylitol over multifunctional heterogeneous catalysts

The present work is focused on the study of aqueous phase reforming reaction (APR) of xylitol, a polyol obtainable from the hemicellulose fraction of lignocellulosic biomass. The APR mechanism as well as the relation within catalyst activity and metal/support properties have been investigated and discussed by changing the main operating conditions (e.g. reaction temperature and time). Interestingly, dedicated test performed by feeding glycerol solutions have underlined the crucial role of preliminary retro-aldol reactions on the xylitol APR which indeed led to glyceraldehyde and glycolaldehyde, both obtained from glycerol as well, which lead to similar products distributions after the catalytic tests. A number of catalysts were evaluated, with interesting results, in terms of H2 yield obtained with polyfunctional material based on supported Pt. Catalyst stability was investigated by recyclability tests and dedicated analysis of the dissolved metals in solution. In this way the most promising catalyst showed to be stable for at least 3 cycles of reaction without any need of intermediate regeneration procedures or usage of harsher reaction conditions.