Novel and efficient cobalt catalysts synthesized by one-step solution phase reduction for the conversion of biomass derived ethyl levulinate

Abstract

Hydrogenation of biomass-derived ethyl levulinate (EL) to gamma-valerolactone (GVL) is an important step in the conversion of sustainable biomass resources into value-added chemicals. Exploration of highly efficient and easily obtainable catalysts is crucial for the large-scale application. In this work, a series of cobalt catalysts were prepared by one-step reduction route in different solvents and applied into the conversion of biomass-derived EL to GVL. Common solvents, including water, methanol, ethanol, glycol and glycerin were attempted as the solvent. Both the solvent effect on the catalyst synthesis and the hydrogenation reaction parameters during the conversion of EL into GVL were systematically investigated. The catalysts were characterized by SEM-EDS, TEM, powder XRD, N2 adsorption-desorption, and XPS. The results demonstrated that the solvents had significant influences on the morphology and structure of the as-prepared catalysts, which changed from dendrite (in water) to spheres (in glycerin). All the catalysts prepared in different solvents were effective for the conversion of EL. Under the optimized conditions, a high GVL yield of 91.4% was achieved when using cobalt catalyst prepared in ethanol at relatively mild reaction conditions. Furthermore, the catalyst could be reused at least 6 times without significant loss of the catalytic activity. As far as we know, this is the first work on the application of cobalt catalysts, synthesized by one-step solution phase reduction method, in the conversion of EL into GVL in biomass utilization.