Get access

A Metal-Free, Carbon-Based Catalytic System for the Oxidation of Lignin Model Compounds and Lignin

Authors

  • Dr. Yongjun Gao,

    1. Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576 Singapore (Singapore)
    Search for more papers by this author
  • Jiaguang Zhang,

    1. Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576 Singapore (Singapore)
    Search for more papers by this author
  • Xi Chen,

    1. Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576 Singapore (Singapore)
    Search for more papers by this author
  • Prof. Ding Ma,

    1. Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, 202 Chenfu Road, Beijing 100871 (P. R. China)
    Search for more papers by this author
  • Prof. Ning Yan

    Corresponding author
    1. Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576 Singapore (Singapore)
    • Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576 Singapore (Singapore)

    Search for more papers by this author

Abstract

Nitrogen-containing graphene material (LCN) has been identified as an effective catalyst for the oxidation of β-O-4 and α-O-4 types of lignin model compounds in the presence of tert-butyl hydroperoxide, to provide aromatic aldehydes, acids and other organic chemicals in high yield. The transformations of five lignin model compounds over LCN were investigated systematically. Instrumentation analysis, kinetic study and radical trapping experiments highlight the mechanistic features of the reaction, including: 1) the reaction pathway starts by benzylic C[BOND]H or C[BOND]OH bond activation, followed by Cα[BOND]Cβ or Cα[BOND]O bond cleavage, and finally further oxidation of intermediate aromatics; and 2) the reaction follows a free-radical mechanism with all the key steps involving radical species. In addition, the LCN proved to be a highly stable catalyst; no significant activity decrease was observed for four consecutive runs, and X-ray photoelectron spectroscopy analysis indicates negligible decrease in the content of the active nitrogen species in the catalyst. Notably, this new catalytic system can be extended to the oxidative depolymerisation of real lignin, to produce a significant portion of liquefied, low-molecular-mass products.

Get access to the full text of this article

Ancillary