First evaluation of multifunctional poly(ionic liquid)s as novel strong bases in directional efficient valorization of lignin

Abstract

Solid strong bases have attracted great research interest because of their excellent catalytic performance in the valorization of lignin into monocyclic aromatic compounds (MCACs). However, the high catalytic efficiency of solid strong bases for obtaining lignin-based MCACs is weakened due to the leaching and deactivation of basic sites caused by H₂O formed in the reaction. More importantly, the precise fabrication of solid strong bases with ordered porous and unique hydrophobicity remains a grand challenge for the development of heterogeneous catalysts. Herein, novel multifunctional poly(ionic liquid)s (MFPILs) with Brønsted–Lewis dibasic sites, well-defined mesoporous channels, and hydrophobicity were successfully fabricated by a regulation-induced copolymerization. In addition, MFPILs show better catalytic performance with 21.99 wt% yield of lignin-based MCACs. The efficient catalytic properties of MFPILs for the directional valorization of lignin into MCACs are attributed to the synergistic catalysis, i.e., the mesoporous confinement, the sequence effect of Brønsted–Lewis dibasic sites on the transfer of active hydrogen, and hydrophobicity. This work not only has a certain guiding significance for the development of novel solid bases, but also provides an efficient catalytic strategy for producing lignin-based MCACs by co-catalysis.