Acid-base synergetic effect and thermal risk assessment on homogeneous catalytic production of γ-valerolactone with formic acid

Sustainable and renewable energy plays a key role in coping with the global energy crisis and increasing demand for development. Biomass valorization is regarded as a potential way to substitute the fossil raw materials in various fields such as electricity, fuel, chemicals, pharmaceuticals, etc. Among the numerous chemicals derived from biomass, γ-valerolactone (GVL) is identified to be an important platform chemical with wide applications. Hydrogenation of levulinic acid (LA) with formic acid (FA) as hydrogen donor for GVL production attracts great attention from the principle of green chemistry. Compared to the enormous efforts on catalyst design, few studies focus on the safety issues of this hydrogenation process, such as thermal runaway risk. Aiming to fill this gap, hydrogenation of LA with FA catalyzed by synthesized homogeneous catalyst Ru-TsDPEN was chosen as a typical efficient process for the production of GVL. In particular, solvent effect and acid-base synergetic effect by adjusting acid-base loading were investigated for process optimization and further calorimetry study. Apparent pH was measured to indicate the strength of acidity and alkalinity of the reaction mixture. Thermal stability of chemicals and thermal risk assessment were performed by differential scanning calorimetry and accelerated rate calorimeter Phi-Tec II, respectively. The results showed significant acid-base synergetic effect on the desired catalytic system and thermal risk was medium under the optimized condition, which needs specific safety measures for loss prevention. Suggestions for inherently safer chemical process for GVL production with FA as hydrogen donor were proposed.