Mild catalytic transfer hydrogenolysis of lignin for efficient monophenol production over lignin-coordinated N-doped ultrafine Ni nanocluster catalyst.

Lignin hydrogenolysis into monophenols presents a promising route for lignin-based chemical and fuel production but still suffers from harsh reaction conditions (e.g. high temperature and high external H 2 pressure). Herein, we report an ultrafine Ni nanocluster anchored on N-doped carbon nanosheets (Ni/LNC) for efficient catalytic transfer hydrogenolysis of poplar organosolv lignin. The catalyst was fabricated through a simple pyrolysis process of lignin‑nickel complex mixed with melamine, in which the lignin coordination greatly improved the Ni dispersion and the strong Ni N interaction inhibited the Ni nanocluster growth, resulting in the ultrafine particle size (1–2 nm). Under mild conditions (160 °C, 1 h), 22.08% of monophenol yield was obtained over the catalyst, which was significantly higher than those over the two reference catalysts (Ni/AC and Ni/LC) as well as other previously reported Ni-based catalysts. The excellent catalytic activity can be attributed to both the substantial increase in catalytic active sites and the enhancement in H transfer from methanol resulted from the electron-rich N-doped nanosheet support. Finally, magnetically recycled Ni/LNC showed excellent recycling stability. Consequently, this work presents a facile and low-cost approach for the synthesis of N-doped carbon nanosheet supported ultrafine Ni nanocluster and further demonstrates its superior applicability in lignin hydrogenolysis. [Display omitted] • Novel Ni/LNC was prepared by simple pyrolysis of melamine mixed Ni-lignin complex. • Ultrafine Ni nanoclusters (1-2 nm) were formed due to lignin coordination and N-anchoring. • High monophenol yield (22.08%) was obtained over Ni/LNC via CTH process at 160 °C. • Ultrafine Ni nanoclusters and N-doping synergistically enhance Ni/LNC catalytic activity. • Magnetically recycled Ni/LNC shows excellent reusability due to strong Ni N interactions. [ABSTRACT FROM AUTHOR]