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 -SO 3 H's) under solvothermal conditions. N 2 isotherms and TEM images showed that H-PDVB- x -SO 3 H'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 -SO 3 H'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 -SO 3 H'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 -SO 3 H'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 -SO 3 H's were more active than those of Amberlyst 15, SO 3 H-functionalized ordered mesoporous silicas, and beta and USY zeolites, which were even comparable with that of homogeneous H 2 SO 4 . 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.