Scalable Preparation of Micro-Meso-Macroporous Polymeric Solid Acids Spheres From Controllable Sulfonation of Commercial XAD-4 Resin

Abstract

Efficient micro-meso-macroporous solid acids spheres with controllable acid strength were successfully synthesized by simultaneous grafting of −SO3H and −SO2CF3 onto the network of commercial XAD-4 resin. The synthesized solid acids are designated as XAD-4-SO3H and XAD-4-SO3H-SO2CF3. Various characterizations show that XAD-4-SO3H and XAD-4-SO3H-SO2CF3 possess high BET surface areas, hierarchical porous structures with combined micro-meso-macropores, high concentrations of acid sites, and strong acid strength. Catalytic tests show that XAD-4-SO3H and XAD-4-SO3H-SO2CF3 exhibit superior activities and good reusability in various acid-catalyzed reactions including esterification of acetic acid with cyclohexanol, acylation of anisole with acetyl chloride, and catalytic synthesis of bisphenol A. Their activities were better than the solid acids of Amberlyst-15, SBA-15-SO3H-0.1, H3PW12O40, and acidic zeolites. This work develops a new method for scalable transformation of commercially macroporous resin into effi...