Conversion of biomass sugar to 5-hydroxymethylfurfural catalyzed by acid-base bifunctional polyphenylene sulfide fiber

This study introduces C-PPS-SN5/1, a polyphenylene sulfide (PPS) fiber catalyst with acid-base bifunctionality for converting biomass sugars to 5-hydroxymethylfurfural (5-HMF). The catalyst combines sulfonic acid and tertiary amine groups through a multi-step process, offering synergistic catalysis. Its innovative PPS fiber design with covalently bonded sites ensures exceptional stability and scalability. Characterization through SEM, XRD, FTIR, XPS, and mechanical tests confirmed its structural integrity, successful grafting, and durability, retaining over 51 % strength after five cycles. By optimizing reaction parameters—including acid-base ratio (5:1), solvent system (NaCl(20 % wt)/DMSO, 1:4 v/v), temperature (160 °C for glucose; 120 °C for fructose), and catalyst loading (5 mol%)—exceptional yields of 92 % (glucose) and 95 % (fructose) were achieved with selectivities of 97 % and 95 %, respectively. The catalyst demonstrated broad substrate applicability, converting sucrose, maltose, galactose, starch, and cellulose to 5-HMF with yields up to 94 %. Remarkably, C-PPS-SN5/1 exhibited outstanding recyclability, maintaining >80 % yield over five cycles, and stability in continuous flow operation (>90 % yield for 72 h). These results underscore the catalyst's potential for scalable, sustainable biomass valorization in industrial settings.