Efficient Conversion of α-Angelica Lactone into γ-Valerolactone with Ionic Liquids at Room Temperature

Abstract

γ-Valerolactone, which can be produced from lignocellulosic biomass, has drawn increasing attention recently because of its benign properties and versatile functions. However, the temperature employed for its production is relatively high. In order to save energy, herein, a new transformation process of α-angelica lactone to γ-valerolactone was carried out by using a series of room-temperature ionic liquids as solvents in a batch-type reactor. Among these ionic liquids, [Bmim]PF6 showed the best performance on the selective hydrogenation at 60 °C with a reaction time of 20 min. Interestingly, it was found that the reaction can also take place at a temperature as low as room temperature with complete conversion and nearly 100% selectivity, which greatly reduces the energy required for the production of γ-valerolactone. The reaction system of ionic liquid/catalyst showed good reusability. There was no obvious decrease in conversion and selectivity after 10 uses. Furthermore, the kinetics of the catalytic hydrogenation reaction of α-angelica lactone was studied to elucidate the reaction profile. Systematic kinetics experiments were carried out by varying the reaction temperature from 20 to 100 °C at 4.0 MPa, and the simulated data fits well with the first-order reaction law.