Selective cleavage of ether C-O bond in lignin-derived compounds over Ru system under different H-sources

Selective hydrogenolysis, the aromatic ether C-O bonds under mild conditions, is crucial for the valorization of lignin. In this context, the effects of H 2 and solvent on the hydrogenolysis of lignin model compounds over Ru catalysts were explored. With H 2 as hydrogen donor, the Ru/AC exhibited the highest activity for converting lignin model compounds into monomeric compounds, whereas H 2 led to low selectivity of aromatics. However, isopropanol was the good H-donor solvent, which could provide a large amount of active hydrogen to promote the cleavage of C-O bonds. Additionally, the yield of aromatics in isopropanol was higher than that under H 2 atmosphere. It could be ascribed to the fact that isopropanol is the protic solvent which displays Lewis basicity, and is a good H-bond donor and a good H-bond acceptor. The higher electron-releasing inductive effect of isopropanol made it easier to provide active hydrogen. Based on the experiments, the mechanism of benzyl phenyl ether hydrogenolysis in H 2 and isopropanol system was presented.