Control the position of framework defects in zeolites by changing the symmetry of organic structure directing agents

Double quantum-single quantum (DQ/SQ) 1H NMR spectroscopy has been used to localize the siloxy/silanol defects in two pure silica MFI zeolite samples synthesized by symmetric tetrapropylammonium hydroxide (TPAOH) and non-symmetric methyltributylammonium (MeTrBA) templates. Using DQ/SQ NMR, we provide important information on positions of structural framework that have tuned during hydrothermal synthesis changing symmetry The preferential location is found be near terminal methyl groups longer alkyl chains far from nitrogen atoms: case MeTrBA template, are located sinusoidal channels, while for TPA template they randomly distributed among types channels. It foreseen control position zeolites might way active sites acid catalysts.