Thermal Risk Assessment of Levulinic Acid Hydrogenation to γ-Valerolactone

The use of biomass as feedstock to produce chemicals or biofuels is increasing. This renewable, biodegradable, and ecofriendly feedstock could present some new risks that should be taken into account. In this context, a thermal risk assessment of levulinic acid (LA) hydrogenation to gamma-valerolactone (GVL), which is a platform molecule produced from the lignocellulosic biomass process, catalyzed by Ru/C in water was performed. A kinetic model including an energy balance under near-adiabatic conditions was built. For that, different experiments at different operating conditions (levulinic acid concentration and catalyst loading) were performed by using an Advanced Reactive System Screening Tool (ARSST) to estimate the kinetic constants of this reaction system. To make a thermal risk assessment of a chemical reaction system, two safety parameters should be defined: Time-to-Maximum Rate under adiabatic conditions (TMRad) and adiabatic temperature rise (Delta T-ad). The parameter TMRad defines the time to reach the maximum temperature rate and characterizes the probability of risk. The parameter Delta T-ad is the difference between the maximum and initial reaction temperature and characterizes the severity of risk. Based on this kinetic model, these two parameters were determined at different operating conditions. With the aid of a risk matrix, it was possible to determine the safe operating conditions (temperature, levulinic acid concentration, hydrogen pressure, and catalyst loading).