KINETICS OF THE RUTHENIUM-CATALYZED HYDROGENATION OF LEVULINIC ACID TO γ-VALEROLACTONE IN AQUEOUS SOLUTIONS

Levulinic acid (LA) is an especially promising feedstock for the production of chemicals and biofuels, because it can be prepared from lignocellulosic biomass. Its conversion to gamma-valerolactone (GVL), a fuel additive and precursor to transportation fuels, appears preferential. In this study, a heterogeneous Ru/C catalyst was employed for investigating the hydrogenation reaction of LA to GVL in the aqueous phase in a three-phase mechanically agitated contactor. To explore kinetics, runs were performed in a chemical-control regime between the temperatures 323-353 K, H-2 partial pressures 0.69-2.07 MPa, initial LA concentrations 4.31-12.93 mmol/L, and catalyst loadings 0.3-0.7 kg/m(3). Langmuir-Hinshelwood-Hougen-Watson (LHHW) models were applied to describe the initial rates of LA disappearance. The model, which presumed that surface reaction between non-dissociatively chemisorbed H-2 and LA is limiting, was most suited to describe reaction kinetics. From an Arrhenius plot, it was found that the value of E-act is 68.1 kJ/mol.