Efficient conversion of lignin fractions in lignocellulose using multifunctional polyoxometalate catalysts

The efficient catalytic conversion of lignin represents a critical challenge in biomass valorization, primarily due to the inherent difficulty in selectively depolymerizing lignin while maintaining the structural integrity of cellulose and hemicellulose. Herein, we present an innovative approach involving the synthesis of ionic liquid polyoxometalate (IL-POM) catalysts, which integrate both redox-active and Lewis acid sites, and are further modified with a choline chloride monomer. Among the synthesized catalysts, ChH₄PMo₁₁Al_0.5V_0.5O₄₀ demonstrated exceptional catalytic performance, achieving an aromatic compound yield of 16.35 % under optimized conditions. Comprehensive characterization of the catalyst revealed that its catalytic efficacy is intrinsically linked to its acidity profile, with the synergistic interplay between Brønsted and Lewis acids facilitating the cleavage of CC and CO bonds. Notably, the incorporation of choline chloride was found to be pivotal in ensuring the catalyst's recyclability. This study underscores the potential of multifunctional IL-POM catalysts in advancing biomass valorization, providing a promising pathway to bridge the gap between homogeneous and heterogeneous catalysis for sustainable biomass conversion.