Process intensification of direct biomass straw conversion to Furfural via circular NaDES platform

The valorization of lignocellulosic biomass represents a key strategy for the sustainable production of platform chemicals without food resources.. Amonf these, furfural is a pivotal C5 building block with applicationsin biofuels, fine chemicals, and pharmaceuticals. In this study, we report a direct and efficient conversion of raw wheat straw to furfural using a natural deep eutectic solvent (NaDES) under mild microwave-assisted conditions, without any preliminary biomass pretreatment.wheat straw to furfural using a natural deep eutectic solvent (NaDES) under mild microwave-assisted conditions, without any preliminary biomass pretreatment. A choline chloride/oxalic acid (1:1) NaDES enabled the selective transformation of the hemicellulosic fraction, affording furfural with >99% selectivity and no detectable HMF formation, as confirmed by GC–MS analysis. The process operates at low temperature (80 °C) and short reaction times, and allows straightforward product separation through cooling and centrifugation. Scale-up experiments demonstrated the robustness and reproducibility of the protocol, with furfural yields up to 20 wt% from untreated straw and 27 wt% from delignified biomass. Importantly, residual furfural remaining in the aqueous phase was further valorized in situ into bi-functionalized cyclopentenones, enabling complete utilization of the produced platform molecule and reinforcing the circular nature of the process. Overall, this work presents a NaDES-based platform for the selective C5 valorization of lignocellulosic biomass, combining process intensification, high selectivity, and circular economy principles.