Sulfonic acid functionalized periodic mesoporous organosilicas as acetalization catalysts

Three types of sulfonic acid functionalized hybrid mesoporous materials AS-MES (arene sulfonic acid ethane-silica), PS-MES (propyl sulfonic acid ethane-silica) and AS-SBA-15 (arene sulfonic acid SBA-15), were synthesized and characterized using XRD, BET, TEM and 13C MAS NMR techniques. The catalytic properties of these hybrid organic–inorganic mesoporous solids were studied using the liquid phase acetalization of heptanal by 1-butanol at 75 °C, which is a water generating reaction. The specific activities per acid site of the hybrid mesoporous solids were compared with those of HY zeolite and Amberlyst-15. Sulfonic acid functionalized mesoporous materials exhibit a good acetalization catalytic activity. The higher heptanal conversion of AS-MES sample is associated with its hydrophobic organosilica framework and the strength of its acid sites. The catalytic results show the predominant effect of the polarity of the channels walls on the reaction rate, and on catalyst deactivation by water.