(600ax) Influence of Reaction Conditions On the Hydrolytic Cellulose Hydrogenation Using Ru/NbOPO4 and Ru/SiO2-TiO2-WO3 Catalysts

Biomass is the most abundant renewable source of carbon and hydrogen. Cellulose can be used as a renewable feedstock for the production of glucose and/or sorbitol that in turn may be used in a biorefinery for the production of fuels and added value chemicals. Here we report the results of the study of the effect of cellulose crystallinity, cellulose/catalyst ratio, reaction temperature and reaction time on the catalytic performance for the conversion of cellulose into sorbitol.  The series of supports studied includes phosphated niobic acid (NbOPO₄) and a ternary metal oxide support SiO₂-TiO₂-WO₃. The materials used, display strong acidic properties. Ru was supported using evaporative deposition on the supports. The catalytic materials were characterized using nitrogen adsorption, X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). For Ru/NbOPO₄, after 30 min of reaction we noticed that by increasing the reaction temperature from 210 to 230 °C, the cellulose conversion increased from 66 to 96% and the yield to hexitols increased from 13 to 43%. However, for Ru/SiO₂-TiO₂-WO₃ the same increase in temperature, causes a proportional increase in the conversion, but a decrease in the yield to hexitols together with an increase in the yields for hydrogenolysis products and gas phase products. For Ru/NbOPO₄ at 230°C, the yield of sugar alcohols is almost constant for reaction times between 5 min and 1h of reaction at an average value of 43%. Furthermore, at this same reaction temperature for Ru/NbOPO₄, 100% cellulose conversion is obtained at 30min, while for Ru/SiO₂-TiO₂-WO₃, 2h of reaction time are required. Decreasing the cellulose crystallinity and/or the cellulose/catalyst ratio increases the cellulose conversion and hexitols yield.