Abstract:
A simple method for the synthesis of nanocrystalline
ZSM-5 and Beta zeolites with trimodal porosity was
developed using starch coated silica nanospheres (as silica
precursor) for generating interparticle porosity (50−200 nm);
propyltriethoxysilane was used as an additive for generating
intercrystalline mesopores (2−50 nm) in the presence of
microporous zeolite porogen. Loading of starch and
propyltriethoxysilane additive played a pivotal role in
obtaining trimodal porosity with very small size zeolite
nanoparticles having high surface area and pore volume.
The possible growth mechanism for the fabrication of
trimodal porous zeolite is presented. The resultant zeolite
demonstrated excellent acidity and activity in the liquid phase acid catalyzed reactions such as esterification of hexanoic/oleic
acid with benzyl alcohol, condensation of benzaldehyde and 2-hydroxyacetophenone, and Friedel−Crafts alkylation followed by
ring closure reaction for the synthesis of vitamin E when compared to conventional zeolite with excellent recyclability. Such an
economical starch mediated synthesis strategy can be extended to other zeolite frameworks and similar heterogeneous catalytic
materials.
