Aqueous phase reforming of sugar-based biorefinery streams: from the simplicity of model compounds to the complexity of real feeds

Glucose, xylose and corresponding sugar alcohols (sorbitol and xylitol) have been subjected to aqueous phase reforming for the production of hydrogen as representative compounds of hemicellulose. The aim of the investigation was to explore new valorization pathways for pentoses sugars, nowadays still not effectively exploited. A developmental platinum-based catalyst supported on carbon was used to perform the reaction in a batch system. The influence of temperature and carbon concentration were investigated in the 230–270 °C and 0.3–1.8 wt.% range, respectively. Moving towards the exploitation of a biorefinery side-stream, wheat straw hydrolysate was subjected to the same reaction conditions. A hydrogenation step was used as pre-treatment to selectively convert the sugars to their corresponding sugar alcohols, and a net hydrogen production was obtained. Deactivation phenomena were investigated during the APR of sugars reusing the catalyst after the reaction. The characterization of the spent catalysts through TGA-IR allowed to confirm the presence of superficial organic deposits responsible for the lack of the catalyst stability