The Relationship between Structure and Catalytic Activity-Stability of Non-Precious Metal-Based Catalysts towards Levulinic Acid Hydrogenation to γ-Valerolactone: A Review

Hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is regarded as the bridge between bio-refinery and the traditional petroleum industry. In recent years, non-precious metal-based catalysts for LA hydrogenation to GVL have attracted much attention owing to their low cost and high efficiency. Metal-involving catalytic hydrogenation of LA is the rate-determining step in the production of GVL, and thus the active site structure of metal-based catalysts governs the overall catalytic performance. Herein, non-precious metal-based catalytic systems including Cu, Zr, Co and Ni are classified into single metal (M = Ni, Cu and Co), bimetallic (Cu–Ni, Ag–Ni, Cu–Co and Co–Zn), metal-heteroatom (M–O and M–N) and heterostructured (CePO4/CoP2 and Ni/NiO) catalysts according to the type of active site structure. The correlation of active site structure with catalytic activity is discussed emphatically, and its relationship with stability is also referred to in terms of strong metal–support interaction, bimetallic synergism, core–shell structure and heterojunction. This review provides an important guide for the rational design of high-performance non-precious metal-based catalysts for the LA-to-GVL process