Deposition of zeolite nanoparticles onto porous silica monolith

A facile and effective method of deposition of ZSM-5 (MFI framework topology) zeolite nanoparticles (nanocrystals) onto macro-/mesoporous silica monolith is demonstrated in this paper. The electrostatic interaction between zeolite and silica monolith was controlled by cationic polyelectrolytes, which were adsorbed onto either silica monolith or zeolite nanocrystals. The effects of time, concentration of zeolite nanocrystals, type of polyelectrolyte and ultrasound treatment were examined. It was found that deposition of nanocrystals on silica monolith modified with polyelectrolyte resulted in a monolayer coverage. Adsorption of nanocrystals modified with polyelectrolyte resulted in a multilayer coverage on the silica monolith due to the agglomeration of particles. On the other hand, the use of excess amounts of polyelectrolyte in the modification of nanoparticles leads to a low coverage of silica monolith by zeolite nanoparticles and is the result of the competition between polyelectrolyte and modified nanocrystals on the silica monolith surface.