Role of gel aging in template-free synthesis of micro and nano-crystalline sodalites

A facile effective stirring aging at room temperature prior to conventional hydrothermal treatment was employed in the template-free synthesis of micro- and nano-crystalline sodalites with two different initial gel compositions. The effect of initial Si/Al molar ratio, NaOH concentration and stirring aging time were investigated on the morphology and particle size of the synthesised sodalites. The results revealed that applying various stirring aging time can change the proportion of the contaminant phase associated with sodalite and alter the morphology of the sodalite crystals from wool ball-like consisting of nano-threads to cabbage- like with nano-leaves, as well as size distribution of nanocrystalline sodalite. The size of the nanocrystals was in the range of 50-80 nm as observed by FE-SEM and the yield was as high as about 15%.