Mesoporous silica supported water-stable perfluorobutylsulfonylimide and its catalytic applications in esterification

A new water-stable perfluorobutylsulfonylimide-functionalized acidic silica (PSFSI-MSMA(15)/SiO2) has been successfully prepared by copolymerization of 4-styrenesulfonyl(perfluorobutylsulfonyl)imide (1) with 3-(trimethoxysilyl)propyl methacrylate (MSMA) followed by condensation with tetraethyl orthosilicate under sot-gel conditions. N-2 isotherm and TEM image showed that the material has high BET surface areas, large pore volumes, and abundant mesoporosity. Acid-base titration analysis gave the acid loading capacities of 0.66 mmol/g. The TG curves and XPS spectra exhibited good thermal stability (<210 degrees C) and hydrothermal stability (only ca. 5% H+ leakage observed) of the material. The material had acid-strength stronger than that of HZSM-5 determined by solid state C-13 NMR spectrum combined with acetone-2-C-13 molecular probe technology. PSFSI-MSMA(15)/SiO2 performed effective in direct esterification of carboxylic acids and alcohols, recycling at least seven run without obvious loss of activity in high reaction temperature. The catalyst's stability towards leaching and the effects of the composition and structure on the catalytic activity are discussed. (C) 2013 Elsevier Inc. All rights reserved.