Catalytic Transfer Hydrogenation of Biomass-derived Levulinates to γ- valerolactone Using Alcohols as H-donors

γ-Valerolactone (GVL) is a kind of significant platform molecules in the modern industry, which can be directly produced from biomass-derivatives, such as sugar, levulinic acid (LA) and ethyl levulinate (EL). In general, GVL could be produced from LA using gas hydrogen as H-donor with heterogeneous or homogeneous catalysts. But this strategy always has the danger of operation and requirement of unique reactors due to explosive hydrogen as well as the acidity of reactant. Over the past decade, researchers in this field have established new processes and strategies to meet the above problems through the CTH process by using alcohol as H-donor and EL as the substrate over different kinds of catalysts. In this review, we collect and discuss the literature on the production of GVL from EL, and applications of LA, EL, and GVL with particular typical mechanisms. The catalyst preparation methods in the mentioned reaction systems are also concerned.