Kinetic modeling of levulinic acid hydrogenation to gamma-valerolactone in water using a carbon supported Ru catalyst

gamma-Valerolactone (GVL) is considered a very interesting green, bio-based platform chemical with high application potential for the production of both biofuels and biobased chemicals. In this contribution, we report a kinetic study on the hydrogenation of levulinic acid (LA) to 4-hydroxypentanoic acid (4-HPA) and the subsequent intramolecular esterification to GVL in water using Ru/C (3 wt.% Ru) as the catalyst in a batch set-up. A large number of experiments was performed in a temperature range of 343-403 K, a hydrogen pressure range from 30 to 60 bar and initial LA concentrations between 300 and 2500 mol m(-3). Experimental data, supported by calculation, indicate that intra-particle diffusion of LA and hydrogen affect the overall reaction rate and as such a heterogeneous model with both reaction and diffusion was used to model the data. The hydrogenation reaction of LA to 4-HPA was modelled using a Langmuir-Hinshelwood type expression whereas the reaction of 4-HPA to GVL was modelled as an equilibrium reaction occurring in the bulk of the liquid, catalyzed by a Bronsted acid, in this case LA and 4-HPA. A good fit between experiments and model was observed. The results were compared to a kinetic model without considering mass transfer and diffusion limitations. (C) 2016 Elsevier B.V. All rights reserved.