Synergistic Catalysis for Promoting Ring-Opening Hydrogenation of Biomass-Derived Cyclic Oxygenates

Biomass has attracted great attention as a carbon source for the production of valuable chemicals and fuels. Selective ring-opening hydrogenation of cyclic oxygenates derived from biomass offers promising approaches for catalytic synthesis of value-added oxygen-containing compounds compared to corresponding fossil-based protocols. Different catalytic sites are required to perform distinct types of elementary reaction steps (e.g., adsorption and activation of oxygen-containing groups, association of a hydrogen molecule), and thus the synergistic effect of these sites plays a critical role in the selective hydrogenation transformation, which has attracted increasing attention in recent years. Here, we present a review of the ring-opening hydrogenation of the representative platforms of furfural, 5-hydroxymethylfurfural, gamma-valerolactone, triacetic acid lactone, and their derivatives catalyzed by various homogeneous and heterogeneous catalysts. The particular focus is placed on the synergistic effect of the active sites, including Bronsted acid, Lewis acid, base, and metallic sites, on the selective scission of two different cyclic C-O bonds and related hydrogenation transformation. The reaction mechanism is also discussed to provide insights for guiding the design of multifunctional catalysts for biomass valorization. Finally, the current challenges and future opportunities in the synergistic catalytic ring-opening transformation of biomass-derived cyclic compounds are also analyzed.