Degradation of lignin catalyzed by nanochannels solid acids in ionic liquid

Abstract Acid treated mesoporous MCM-41 molecular sieves were adopted as catalysts for degradation of lignin dissolved in ionic liquid. On one hand, the acid sites doped the nanochannels activate lignin macromolecules to conduct degradation reaction, on the other hand, the confined spaces are benefit for restricting the repolymerization of the degraded lignin fragments. The AMCM-41s catalyst was found to be the best species for lignin degradation in 1-methyl-3-benzylimidazolium chloride (BnMIMCl) within the domain of present study. The efficiency of lignin degradation was increased to 74.02% under the optimal conditions. Meanwhile, over 80% of the liquid products were tested as phenols. The surface area, pore sizes and their distribution as well as the acidity of the acidified MCM-41 catalysts were analyzed, which were properly interconnected with the lignin degradation efficiency. This work contributes a degradation process for lignin in homogeneous solution under heterogeneous catalytic process, which is promising for obtaining phenols from lignin with the aid of green solvent. Furthermore, the recycled solid residues were fully transferred into activated carbon with excellent adsorption property for methylene blue and iodine.