Reductive catalytic fractionation of lignocellulose over copper phyllosilicate nanotube catalysts

Reductive catalytic fractionation of lignocellulose is a promising biorefinery strategy that combines biomass fractionation with lignin depolymerization. Herein, we report a layered copper silicate nanotube (RCuSNT) catalyst, which exhibits enhanced performance toward reductive fractionation of lignocellulose. The phenolic monomers obtained from lignin are close to the theoretical maximum yields (22.5 wt% for softwoods and 38.5 wt% for hardwoods), with high selectivity for propyl and propanol end-chain phenolic compounds. The result indicates that lignin is successfully deconstructed while cellulose and hemicellulose are retained essentially intact (88.4 wt%). The catalyst shows stability in recovery experiments, which is attributed to the immobilization of copper species by the leaf silicate. Moreover, a series of lignin model compounds and isotope-labeled reactions clarify the mechanism of C-O bond scission over RCuSNTs. This work provides a significant benchmark for the rational development of inexpensive metal catalysts in reductive catalytic fractionation systems for lignin valorization.