Directing reaction pathways in tandem catalysis: How acid-base sites govern HMF valorization to furan diethers

The efficient synthesis of biomass-derived 2,5-bis(isopropoxymethyl)furan (BPMF) as a high-quality biofuel depends critically on the regulation of acid-base catalytic pathways during the hydroetherification of 5-hydroxymethylfurfural (HMF). In this work, a series of Zr-S/C_xN_y catalysts with tunable acid-base properties were developed to direct the reaction selectivity and suppress side reactions. By introducing Lewis basic sites, the optimized catalyst shifts the pathway from reversible etherification toward consecutive conversion via BHMF, achieving 95.8 % BPMF yield under mild conditions. The correlation between active site distribution and intermediate transformation was elucidated, offering both a practical strategy for furanic ether production and fundamental insights for rational catalyst design.