Single-atom Cu catalyst in a zirconium-based metal–organic framework for biomass conversion

• Single Cu atoms catalyst of Cu@UiO-66-(COOH) 2 was designed and synthesized. • High performance of LA hydrogenation to GVL was achieved via CTH route. • The defective sites of metal nodes in MOF facilitated the stabilization and anchoring of Cu atoms. • The atomic dispersion of Cu atoms with the aid of electron-withdrawing group in MOF was responsible to the high performance. Single-atom catalysts (SACs) have received great interests due to their high atomic utilization efficiency and unique electronic properties of active center atom. Here we reported a single-atom catalyst, Cu@UiO-66-(COOH) 2 , prepared by a simple, facile, and efficient solvothermal strategy, where Cu atoms were coordinated to the defect sites of secondary building units (SBUs) in a Zr-based metal-organic framework (MOF) UiO-66-(COOH) 2 . The single-atom Cu@UiO-66-(COOH) 2 catalyst exhibited high activity for biomass derived platform chemical levulinic acid (LA) hydrogenation to γ-valerolactone (GVL) through catalytic transfer hydrogenation (CTH) process using isopropanol (IPA) as hydrogen donor under mild reaction conditions, where 96.7% GVL yield was achieved. The site isolation and uniform distribution of single Cu atoms combined with the aid of acid sites in MOF, attributing to the excellent catalytic performance for biomass upgrading.