Aqueous phase reforming of xylitol and sorbitol: Comparison and influence of substrate structure

• Published in: Applied catalysis. A, General Vol. 435-436; pp. 172 - 180
• Main Authors: Kirilin, Alexey V., Tokarev, Anton V., Kustov, Leonid M., Salmi, Tapio, Mikkola, J.-P., Murzin, Dmitry Yu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.09.2012
• Subjects: Aqueous reforming; Biomass conversion; Catalysis; Catalysts; Hydrogen; Liquids; Polyols; Pt/Al2O3; Reforming; Selectivity; Sorbitol; Xylitol; Xylitol; Pt/Al2O3; Catalysis; Biomass conversion; Hydrogen; Aqueous reforming
• ISSN: 0926-860X; 1873-3875; 1873-3875
• DOI: 10.1016/j.apcata.2012.05.050

[Display omitted] ► Aqueous phase reforming of xylitol was studied over Pt/Al2O3 catalyst. ► Stable catalyst performance over 160h time-on-stream. ► Higher selectivity to H2 compared to sorbitol. ► Advanced reaction network based on the substrate structure was proposed. The behavior of abundant polyol stemming from hemicelluloses, xylitol, was investigated in the aqueous phase reforming (APR) over supported Pt/Al2O3. The data obtained in the case of xylitol was compared to aqueous phase reforming of sorbitol under the same operating conditions. The effect of weight hour space velocity on the performance of a catalytic system as well as on selectivity toward hydrogen and alkanes was studied. The catalyst showed stable performance with insignificant deactivation over 160h time-on-stream. The selectivity toward H2 diminished from 86 to 70% within 120h. The regeneration of the catalytic system in a H2 flow allowed to recover the catalyst activity and to improve selectivity toward H2 to 75%. It was found that both polyols demonstrated similar behavior in the APR in the whole range of space velocities studied. The selectivity toward H2 went through a maximum in the case of xylitol and sorbitol when changing a space velocity. This behavior was attributed to a number of side reactions which involved hydrogen thus leading to its consumption. Additionally, the yields of target APR product, hydrogen, were higher in the case of xylitol compared to sorbitol due to the longer carbon chain in the latter substrate. The plausible reaction network based on the hypothesis that APR process proceeds through the terminal position of polyol was proposed to explain similarity in the gas and liquid product composition in the APR of xylitol and sorbitol. The reaction scheme describing formation of the main gas and liquid products via various pathways was proposed and discussed. The results obtained and explanations provided are in perfect agreement with the results obtained for other feedstocks in the literature.