Synthesis of zeolite/mesoporous silica composite microspheres by microemulsion method

Zeolite/mesoporous silica composite microspheres (ZMMS) have been prepared by self-assembling mesoporous silica phase with Y or Ti-MWW zeolites crystallites in a simple microemulsion system. The synthesis process involved the formation of a stable O/W microemulsion from silica precursor of tetrabutyl orthosilicate and cationic quaternary ammonium surfactants as well as a simultaneous assembling of zeolite into the oil phase by their hydrophobic interaction, in which mesoporous silica was formed by self-assembling of surfactant and silica source. Through optimizing synthesis conditions, the ZMMS materials were prepared to possess controllable mass ratio of zeolite to mesoporous silica (0-2.3) and sphere diameter (186-965 μm). The mesopore sizes of the ZMMSs were 3.75 (zeolite-Y/MMSs) and 3.98 nm (Ti-MWW/MMSs). In the liquid-phase ammoximation of cyclohexanone, Ti-MWW/mesoporous silica microspheres showed a high mechanical stability and a catalytic activity comparable to the parent Ti-MWW powders.