Decatungstate-Based Ionic Liquid Highly Active Under Mild Conditions for Upgrading Recalcitrant Humins from Biorefineries

Among all the materials resulting from the recovery of biomass, humin coproducts are produced today on a large scale, particularly in the sugar industry and biorefineries. Humins formation, with typical yields between 10 and 50 wt %, significantly reduces the efficiency and economic viability of the processes. With their complex structure, low solubility, and low reactivity, their valorization constitutes a real challenge. This paper aims to establish the proof of concept for the transformation of recalcitrant humins into high-value-added biobased products using polyoxometalate-based ionic liquids (POM-ILs) under “mild” conditions. In this contribution, the POM-IL (P_6,6,6,14)₄[W₁₀O₃₂] is used in the presence of H₂O₂, at atmospheric pressure and 90 °C for just 1 h. This system proved to be a powerful oxidizing catalyst for the extensive depolymerization of humins and their valorization into platform molecules. Under these conditions, the humin powder underwent an almost complete oxidative dissolution in the 94–99% yield range, leading to the formation of various carboxylic acids of industrial interest and sugars.