Zr/Ti-catalyzed efficient synthesis of fuel additive γ-valerolactone from bio-based ethyl levulinate

Abstract

This study focuses on conversion of ethyl levulinate (EL) to γ-valerolactone (GVL) in 2-propanol with catalysts comprising of Zr and Ti. In this context, a series of Zr x Ti10-x mixed oxides were prepared via a simple co-precipitation method and further examined as potential acid-base bifunctional heterogeneous catalysts for cascade reaction of hydrogenation and cyclization of EL into GVL in 2-propanol. A high GVL yield of 93% at a conversion of 99% EL was achieved over Zr5 Ti5 at 210 °C after 4 h. Several characterization techniques including XRD, N2 -physisorption and thermogravimetric (TG), NH3 /CO2 - temperature programmed desorption (TPD), along with different reaction parameters (e.g., Zr/Ti ratio, reaction temperature and time) were performed to investigate the activity-structure relationship between prepared catalytic materials and the conversion of EL-to-GVL. Moreover, the recycling experiments revealed that the Zr5 Ti5 catalyst could maintain a near constant selectivity toward on the yield of GVL for at least five consecutive catalytic runs.