In Situ Preparation of Ru@N-Doped Carbon Catalyst for the Hydrogenolysis of Lignin To Produce Aromatic Monomers

A high-performance catalyst is the key to selectively convert lignin into aromatic monomers. In this study, Ru@N-doped carbon catalysts were prepared in situ by a two-stage pyrolysis of a mixture of d-glucosamine hydrochloride (GAH) and ruthenium trichloride with melamine acting as a soft template. The layered graphitic carbon nitride (g-C₃N₄) and the well-wrinkled, mesoporous graphitic carbon with doped nitrogen atoms were formed after the pyrolysis at 600 and 800 °C, respectively. For the latter catalyst, the incorporation of either pyridinic or pyrrolic N atoms on the graphitic carbon support could not only homogeneously disperse and stabilize the Ru nanoparticles (NPs) but also create the defect-rich carbon structure. Compared with commercial Pd/C and Ru/C catalysts, the Ru@N-doped carbon catalyst contributed to higher catalytic activity for lignin depolymerization. The yield of the aromatic monomers reached ∼30.5% over the optimal catalyst at 300 °C.