Design and Synthesis of Mesoporous Polymer-Based Solid Acid Catalysts with Excellent Hydrophobicity and Extraordinary Catalytic Activity

Abstract

Novel excellent hydrophobic- mesoporous- polymer-based solid acid catalysts have been successfully synthesized by copolymerization of divinylbenzene (DVB) with sodium p-styrene sulfonate (H-PDVB-x-SO3H's) under solvothermal conditions. N2 isotherms and TEM images showed that H-PDVB-x-SO3H's have high BET surface areas, large pore volumes, and abundant mesoporosity; CHNS element analysis and acid–base titration technology showed that H-PDVB-x-SO3H's have adjustable sulfur contents (0.31–2.36 mmol/g) and acidic concentrations (0.26–1.86 mmol/g); TG curves showed that H-PDVB-x-SO3H's exhibited much higher stability of the active site (372 °C) than that of the acidic resin of Amberlyst 15 (312 °C); contact angle and water adsorption tests showed that H-PDVB-x-SO3H's exhibited excellent hydrophobic properties. Catalytic tests in esterification of acetic acid with cyclohexanol, esterification of acetic acid with 1-butanol, and condensation of benzaldehyde with ethylene glycol showed that H-PDVB-x-SO3H's were more active than those of Amberlyst 15, SO3H-functionalized ordered mesoporous silicas, and beta and USY zeolites, which were even comparable with that of homogeneous H2SO4. The superior hydrophobicity of solid acid catalysts would be favorable for achieving excellent catalytic performance because water usually acts as a byproduct in various acid-catalyzed reactions, which can easily poison the acid sites and result in opposite reactions. Synthesis of porous solid acid catalysts with good hydrophobicity would be very important for their applications.