Effects of Solid Acid Supports on the Bifunctional Catalysis of Levulinic Acid to γ-Valerolactone: Catalytic Activity and Stability.

Heterogeneous transformation of levulinic acid (LA) to gamma-valerolactone (GVL) is regarded as a critical process of the lignocellulose-based biorefinery system. Substantial progress on the catalytic conversion of LA to GVL has been continuously achieved recently. However, the traditional research paradigm typically emphasizes the metal-catalyzed hydrogenation step, but lacks profound insights into the potential impacts of catalyst supports. Herein, an overview of the bifunctional catalytic system classified by representative solid acid supports for LA conversion to GVL is presented, and effects of critical factors on metal- and acid- catalyzed processes are discussed. Particularly, impacts of key issues on catalytic stability are thoroughly summarized and analyzed. Challenges and suggestions are also proposed from the perspective of increases in both catalytic activity and stability. This review potentially contributes to the rational design of high-efficiency catalysts used in the biomass valorization for renewable energy production.