Interfacial engineering of ReOx sites with ZrO2 clusters boosts active site formation for efficient cross-metathesis of methyl oleate - ScienceDirect

Abstract

The cross-metathesis of bio-derived unsaturated fatty acid esters to high-value long-chain α-olefins presents a sustainable alternative to petroleum routes, where supported rhenium catalysts are effective under mild conditions. However, the low utilization efficiency of rhenium in supported ReOx/Al2O3 catalysts, stemming from slow activation kinetics to form metathesis-active Re-alkylidene intermediates, remains a major bottleneck. We demonstrate that decorating ReOx/Al2O3 with ZrO2 clusters markedly enhances the cross-metathesis of methyl oleate and ethylene by tuning the local environment of Re centers. Detailed characterizations (XRD, electron microscope, in situ Raman spectra, in situ DRIFTS, XAFS, NMR) and DFT calculations reveal that ZrO2 clusters establish an intimate interfacial interaction with isolated ReOx species, allowing for strong electronic coupling. This interfacial coordination donates electron density to the Re centers, weakens the terminal Re O bond, and strengthens olefin adsorption, thereby accelerating the formation of active Re-alkylidene intermediates. With 2 wt% ZrO2 addition, the catalyst achieves a turnover number 8.8 times higher than the undecorated counterpart, delivering 72% methyl oleate conversion with 93% selectivity to C10 products while improving Re utilization from 13.6% to 36.0%. This work highlights the critical role of local environmental modification of ReOx/Al2O3 catalysts to improve the active site formation kinetics for enhancing cross-metathesis activity, advancing the design of high-performance catalysts for biomass valorization.