Ultrafine Ru nanoparticles deposited on lignin-derived nitrogen-doped carbon nanolayer for the efficient conversion of levulinic acid to -valerolactone

Carbon-supported Ru-based catalysts have shown great potential in the hydrodeoxygenation of biomass-derived chemicals but still suffer from the uneven/unstable metal loading owing to the weak affinity between the metal and the carbon-based support. Herein, novel ultrafine Ru nanoparticles supported on lignin-derived nitrogendoped carbon layers (Ru/LNC) were prepared through a facile pyrolysis of lignin-Ru complex mixed with melamine and further subjected to the hydrodeoxygenation of levulinic acid (LA) into gamma-valerolactone (GVL) using formic acid (FA) as the H-donor. The formation of lignin-Ru complexes and abundant N-anchoring sites collaboratively improve the dispersion of metals, thus forming the ultrafine Ru nanoparticles (similar to 3 nm). Meanwhile, the base site generated by nitrogen -doping promotes the adsorption of acidic reactants (FA and LA) to improve the catalytic performance. Therefore, Ru/LNC catalyst exhibited outstanding catalytic performance (99.5 % of LA conversion and 98.4 % of GVL yield), which was significantly higher than Ru/LC (without N doping) and Ru/C (fabricated through convention impregnation method). Owing to the strong interaction of N species and Ru nanoparticles, Ru/LNC also exhibited improved reusability. Consequently, this work proposes a novel route to fabricate ultrafine Ru nanoparticles embedded on lignin-derived nitrogen-doping carbon nanolayer and further demonstrates its superior applicability in LA hydrodeoxygenation.