Engineering reverse H-spillover on Ru single-atom sites for selective upgrading of lignin-oil to aviation fuel precursors.

Lignin-oil remains the last untapped carbon reservoir in biomass refineries because its dense aryl-O-aryl networks resist selective C-O cleavage. The key to this transformation lies in the selective deoxygenation of its oxygen-containing groups and the selective scission of bonds between polycyclic aromatic hydrocarbons; whether the surface can return H* to metal centres to trigger cracking is unknown. Here we elucidate a reverse H-spillover pathway on Ru single-atom catalysts (Ru1/WZrOx) that enables C-O cleavage of crude lignin-oil directly to produce value-added aviation fuel precursors, boosting the hydrodeoxygenation efficiency by 40%. Surprisingly, a remarkable substrate conversion of 100% and selectivity of 100% to produce cycloalcohols are achieved, while delivering an impressive 80.7% selectivity toward C-O cleavage from lignin-oil. Detailed spectroscopy, isotope experiments and density functional theory analysis disclose that sp3-hybridized W centres in defective WZrOx nanolattices chemically push electron-rich hydrides back to Ru single-atoms, while micro-kinetics of dual-supplied H* system identify a 0.09 eV barrier for arene-O hydrogenolysis inside a Ru-hydride, leading to highly active lignin-oil hydrocracking. This study is expected to provide deep insights into boosting efficient lignin-oil depolymerization via modulating the surface active sites of the catalyst, for converting lignin-oil into hydrocarbon mixtures suitable for aviation fuel.