Synthesis of mesoporous LTA zeolites with large BET areas

Abstract

Mesoporous LTA zeolites were successfully synthesized by performing a direct hydrothermal synthesis using tetraethylorthosilicate (TEOS) and an organosilane surfactant as the silicon source and the mesopore-generating agent, respectively. The as-synthesized materials were characterized using a complementary combination of X-ray diffraction, nitrogen adsorption–desorption measurements, scanning electron microscopy, and transmission electron microscopy. The characteristics of the samples are comparable with the materials synthesized with sodium metasilicate nonahydrate as the silicon source. The influence of the adding amount of the amphiphilic organosilane [3-(trimethoxysilyl)propyl]-tetradecyl-dimethylammonium chloride on the mesoporous and microporous properties of the samples were investigated. Our results indicate that the materials synthesized with TEOS possess a mesoporous-microporous hierarchical structure. Moreover, the synthesized materials have a large Brunauer–Emmett–Teller area of up to 244 m2/g and present consistent mesopore diameter distributions centered at approximately 4.6 nm. The results of thermogravimetric analysis prove that more amphiphilic surfactant molecules bond to the LTA zeolite framework surface synthesized using TEOS.