(629u) Effect of the Support of Metal Oxide Supported Ruthenium Catalysts for the Conversion of Cellulose Into Sugar Alcohols

The increase of the world’s energy needs with the combination of several factors including the diminishing of petroleum resources, the increase in the petroleum derivatives prices, as well as the increase of green house gas emissions, have caused great interest of finding new processes to produce renewable fuels, such as the hydrogenation of cellulose by a bifunctional catalyst into sugar alcohols.  In this work, we focus on the study of the effect of the support acid-base properties on the catalytic performance during the conversion of cellulose into sugar alcohols, which can be used in a biorefinery platform as a renewable feedstock for the production of fuels and high value chemicals.  The series of metal oxide supports studied includes MgO, ZrO₂, TiO₂, two types of Nb₂O₅, Al₂O₃, and SiO₂. Furthermore, binary and ternary metal oxides were also analyzed such as two types of SiO₂-TiO₂, WO₃-TiO₂, Al₂O₃-TiO₃, Fe₂O₃-TiO₂ and SiO₂-TiO₂-WO₃.  The materials used display a wide range of acid-base properties.  Ru was supported using evaporative deposition on all the supports.  The catalytic activity appears to have a correlation with the Sanderson electronegativity for the single metal oxide materials passing through a maximum for Ru/Nb₂O₅ for the supported catalyst and through ZrO₂ for the supports.  The catalytic materials were characterized using nitrogen adsorption, X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR).  Ru/Nb₂O₅ has a significantly lower surface area than Ru/SBA-15 but displays higher activity. The selectivity of the mesoporous material is equally better than that of Ru/Nb₂O₅.  On the other hand, the structural differences between SiO₂ and SBA-15 results in a significant difference in selectivity, and smaller effect over the activity.  The binary metal oxide TiO₂-WO₃ had a better activity and selectivity than SBA-15, probably due to its more acidic character. Ru/TiO₂-WO₃ displayed the best cellulose conversion; on the other hand Ru/SiO₂-TiO₂-WO₃ shows better selectivity to sugar alcohols.  Also it is seen that the identity of nonporous supports has small effect on cellulose hydrogenation activity.