Resin-Type Solid Acid as an Efficient Heterogeneous Catalyst for Dehydration of Xylose to Furfural in Alcohol/Water Medium

Furfural, a pivotal platform compound in biorefineries, has emerged as the high-value chemical among furan derivatives due to its versatile applications in solvents, pharmaceuticals, and polymer precursors. Compared to conventional pentosan-based routes, xylose-based synthesis demonstrates superior advantages, including precise reaction control and enhanced feedstock sustainability. Optimizing catalyst design proves crucial for boosting the xylose-to-furfural conversion efficiency. In this work, a sulfonated polystyrene (SPS) catalyst was fabricated via a facile one-step sulfonation protocol. This engineered catalyst exhibits dual superiority: remarkable catalytic performance with 98.38% xylose conversion and 74.4% furfural yield was achieved within 10 min in a water-n-pentanol biphasic system, with 80% of the product selectively partitioned into the organic phase. It not only reduces energy consumption during the reaction process but also lowers the separation and purification costs of downstream products. Reaction kinetic studies further revealed a significantly low activation energy for the xylose dehydration pathway, which thermodynamically favors furfural formation. The SPS catalyst demonstrated exceptional reusability, retaining 92.07% of its initial activity after 6 reuses, attributed to its robust covalent sulfonic group anchoring. Characterization of the catalysts under different usage conditions through acid amount measurements, elemental analysis, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy revealed that the catalysts retained abundant acidic sites even after multiple uses. This excellent performance is attributed to their robust covalent sulfonic acid group anchoring structure. This work not only provides a green and sustainable catalytic system with industrial-scale potential but also establishes foundational insights into the xylose conversion mechanism.