III International Conference

PP-II-71PREPARATION EFFECT ON THE STRUCTURE AND CATALYTIC PROPERTIESOF SULFONIC ACID FUNCTIONALIZED SILICA MESOSTRUCTUREDCELLULAR FOAMSMaresz K., Malinowski J., Jarzębski A., Mrowiec-Białoń J.Institute of Chemical Engineering Polish Academy of Science, Gliwice, PolandE-mail: j.bialon@iich.gliwice.plStructural and catalytic properties of sulfonic acid functionalized silica mesostructuredcellular foams (MCF) were prepared using different procedures and precursors of sulfonicgroups. Catalytic activity tested in the esterification of butanol with acetic acid was found todecrease in the order MCF-et-ph-SO 3 H> MCF-ph-SO 3 H> MCF-propyl-SO 3 H. The catalystscan be used repeatedly without loss of the activity during several cycles. Structural stability ofmaterials after few catalytic cycles appeared to be excellent.Porous materials functionalized with sulfonic acid groups are promising solid acidiccatalyst which attract much attention because they overcome the traditional drawbacks of theuse of liquid acids such as difficulties in separation, corrosiveness, formation of toxic wastesand hazards in handling.In this work we compare the catalytic and structural properties of functionalized silicamesostructured cellular foams (MCFs) obtained by direct incorporation via co-condensationor post-synthesis grafting with three precursors: mercaptopropyltrimethoxysilane,phenyltriethoxysilane, 2-(4-chlorosulfonyl fenyl)ethyltrichlorosilane. The oxidation of thiol tosulfonic groups was carried out using 30 % aqueous solution of H 2 O 2 . Phenyl groups weresulfonated by 20 % of oleum or by chlorosulfonic acid. Typical structure parameters of puresilica MCFs were: specific surface area (S BET ) 600-650 m 2 /g, mesopore volume(V p ) ca. 2.4 cm 3 /g, pore diameter of spherical cage (d s ) ca. 24 nm, and of connecting windows(d w ) 12 nm. Samples obtained by grafting well preserved the cage-like structure of theoriginal MCF. Only specific surface area decreased to 350-550 m 2 /g, whereas pore volumedecreased by about 0.5 cm 3 /g and pore diameters by 2-4 nm. Direct incorporation offunctional groups resulted in materials with small mesopores (3-6 nm) and pore volume ofabout 0.8-1.0 cm 3 /g.Thermal stability of SO 3 H-MCFs, determined by thermogravimetric method, appeared toincrease in the order MCF-propyl-SO 3 H< MCF-ph-SO 3 H< MCF-et-ph-SO 3 H. Decompositionof the first sample begins at about 523 K whereas the last one is stable up to 673 K.294