Boosting catalytic transfer hydrogenation of alkyl levulinate to γ-valerolactone using ionic liquid modified UiO-66

[Display omitted] •The formed W-N/O bond in UiO-66@IL(HPW) contributes to superior catalytic activity.•Lower apparent activation energies are displayed for UiO-66@IL(HPW) than UiO-66@HPW.•100% of ethyl levulinate conversion and 93.1% GVL yield can be achieved.•The catalyst shows good recyclability, and can be reused for at least seven runs. An effective strategy is proposed here for transfer hydrogenation of alkyl levulinate to γ-valerolactone (GVL) using a UiO-66 framework modified with phosphotungstate ionic liquid (UiO-66@IL(HPW)). Due to the intensive influence of ionic liquid fragment, the modification significantly enhances the catalytic activity of UiO-66@IL(HPW), leading to a complete conversion of ethyl levulinate with over 93.1% selectivity for GVL. Characterizations techniques, including XRD, N2 absorption/desorption, SEM, FT-IR, pyridine FT-IR, NH3-TPD and CO2-TPD, confirm that while the basic structure of UiO-66-NH2 is insignificantly changed, the introduction of the ionic liquid greatly improves the acidic/base properties of the catalyst. XAFS and XPS results reveal an intensive interaction between the N and W species in UiO-66@IL(HPW), and the formed W-N/O moiety is responsible for the enhanced catalytic activity. In addition, a plausible catalytic mechanism is proposed based upon in situ DRIFTS and density functional theory (DFT) calculations, highlighting the crucial role of ionic liquid fraction within the UiO-66 ligand. Therefore, this work would contribute to the valorization of biochemicals.