Selective aqueous-phase hydrogenation of glucose and xylose over ruthenium-based catalysts: Influence of the support

Abstract

Sorbitol and xylitol are value-added renewable chemicals that can be obtained from biomass through the hydrogenation of monosaccharides (glucose and xylose, respectively) using ruthenium-based catalysts. This paper reports an in depth study on the activity and selectivity of Ru catalysts supported on different materials, gamma alumina (A), zirconia (Z), zirconia-alumina (Z-A), phosphated zirconia (ZP) and phosphated zirconia-alumina (ZP-A), focusing on the effect of the support. Catalyst performance was evaluated under relatively mild reaction conditions, 90 °C, 1.25 MPa H2 pressure and water as solvent. The results showed that the activity greatly depends on the support used. The most active catalyst analyzed in the present paper, Ru/ZP-A, gave a selectivity of 97% and 97.5% towards sorbitol and xylitol, at high conversion levels of glucose and xylose (over 85%), respectively. Characterization of the catalysts by N2 physisorption, XRD, TGA, SEM, TEM, TPR and XPS provided valuable insight in the relation between the catalyst structure and its activity.