Oxidative Cleavage of β‐O‐4 Linkage in Lignin via Co Nanoparticles Embedded in 3DNG as Catalyst**
Jiali Zhang, Puyi Lei, Daobo Yu, Yanfang Li, Min Zhong, Wenzhuo Shen, Shouwu Guo
Abstract
Abstract The cleavage of β‐O‐4 linkage in lignin is one of the key steps for oxidative conversion of lignin to low‐molecular‐weight aromatics. Herein, Co nanoparticles embedded in three‐dimensional network of nitrogen‐doped graphene (Co/NG@3DNG‐X) were prepared through an immersion‐pyrolysis procedure, in which X denotes the pyrolysis temperature. The detailed characterization of Co/NG@3DNG‐X shows that the Co nanoparticles are coated with a few layers of nitrogen‐doped graphene (NG) sheets that are further embedded in 3DNG matrix. The catalytic activities of the Co/NG@3DNG‐X for the oxidative cleavage of β‐O‐4 linkage in lignin model compounds with O 2 as oxidant are explored. It is demonstrated that catalytic activities of as‐prepared Co/NG@3DNG‐X can be tuned by varying the pyrolysis condition, and the Co/NG@3DNG‐900 shows the highest catalytic activity, which is attributed to the enriched Co‐N x species, the strong surface basicity, the high specific surface and the mesoporous motif of 3DNG network. More pronouncedly, the Co/NG@3DNG‐900 can also effectively catalyze the oxidative cleavage of organosolv lignin, generating certain monomeric aromatics. Additionally, the intrinsic magnetic property of Co nanoparticles makes the Co/NG@3DNG‐X be easily recovered from the reaction mixture, and the as‐coated thin NG layer can protect Co nanoparticle from oxidation condition, which putting together afford the Co/NG@3DNG‐X with good reusability and stability.