Kinetics study of the Ru/C-catalysed hydrogenolysis of polyols – insight into the interactions with the metal surface

Abstract

The aqueous Ru/C-catalysed hydrogenolysis of xylitol and sorbitol was studied in a temperature range between 393–443 K under 6 MPa H₂. For the three main reactions, stereoisomerisation, decarbonylation and deoxygenation, kinetic models were formulated and fitted to the experimental data. The obtained rate constants were used to determine apparent activation enthalpies via the Eyring method. The data reveals a clear dependence of the type and position of the reacting hydroxyl group as well as the length of the polyol on the activation energies. It is proposed that these differences are the result of increased stabilisation due to polydentate interactions with the metal surface.