Coordination-Driven Self-Assembly of Schiff-Base-Tagged Ni–ZrO₂/N–C Nanocatalysts for Selective Transformation of Renewable Methyl Levulinate

By functionalizing organic ligands and regulating metal nodes, metal–organic frameworks (MOFs) exhibit a variety of catalytic properties, which not only expand their application in biomass conversion but also increase the designability of catalysts. Herein, we have developed a synthesis strategy to fabricate multicomponent nanocatalysts (M–ZrO 2 /N–C, M = Ni, Fe, Co, Cu) derived from postsynthetic modification of zirconium–organic frameworks using Schiff base as an effective bridge. These nanocatalysts were utilized for the hydrogenation of bio-derived methyl levulinate to γ-valerolactone. The catalytic performance demonstrates that Ni–ZrO 2 /N–C possesses superior catalytic activity (99.9% conversion of methyl levulinate and 94.7% selectivity of γ-valerolactone), which could be attributed to the synergy effect of metal Ni and ZrO 2 species. Various characterization methods (X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)) indicated that metallic nickel activated H 2, and the introduction of ZrO 2 provided sufficient Lewis acid sites, accelerating the intramolecular esterification process.