Oxidative Catalytic Depolymerization of Technical Lignins to Vanillin(Derivatives) Using Polyoxometalate Catalysts

Abstract

The transition from fossil‐based resources to renewable feedstocks is a cornerstone of industrial decarbonization. Among renewable resources, lignin stands out as a promising candidate due to its wide availability, abundance, and non‐competitiveness with food production, making it an ideal starting material for a sustainable chemical industry. Herein, an oxidative depolymerization strategy for the polyoxometalate (POM)‐catalyzed valorization of technical lignins to monoaromatic compounds like vanillin, methyl vanillate, syringaldehyde, and methyl syringate is demonstrated. Compared to existing research, this work systematically compares the catalytic oxidation of various technical lignins through a rigorous study of lignin type, solvent composition, reaction conditions, and POM catalyst. It elegantly combines the highly selective H 15 PNi 3 Mo 9 O 40 (HPMo‐Ni 3 ) POM‐catalyst with the optimal solvent system (methanol/water), achieving a high yield of monoaromatic compounds up to 13 wt % under optimized reaction conditions. The catalyst could be simply recycled by nanofiltration, demonstrating a stable catalytic performance over multiple runs.