Ru/CeO2 catalyst with optimized CeO2 morphology and surface facet for efficient hydrogenation of ethyl levulinate to γ-valerolactone

Three Ru/CeO2 catalysts with different CeO2 morphology (nanorod, nanocube and nano-octahedra) mainly exposed (1 1 0) + (1 0 0), (1 0 0) and (1 1 1) facets for hydrogenation of biomass-derived ethyl levulinate (EL) to valuable gamma-valerolactone (GVL). Ru/CeO2-rod with exposed (1 1 0) crystal plane obtained the highest GVL yield (99.4%) and best productivity (13140 h(-1)). The surface facets of CeO2 supports not only affect the chemical states of Ru species but also tune the concentration of oxygen vacancy in Ru-CeO2 interface. The concentration of oxygen vacancy shows a linear relationship with GVL production rate. DFT calculations indicate that the lactonization of CH3CHOCH2CH2CO* to produce GVL is the rate-determining step in EL hydrogenation, and Ru-10/CeO2 (1 1 0) with more oxygen vacancy has low activation energy barrier, compared to Ru-10/CeO2 (1 0 0) and Ru-10/CeO2 (1 1 1). (C) 2020 Elsevier Inc. All rights reserved.