Organic group-bridged hybrid materials with a Faujasite X zeolite structure (ZOF-X)

Zeolites with organic group-bridged inorganic frameworks (ZOFs) with a Faujasite X zeolite structure (ZOF-X) and a Si/Al ratio around 1.3 have been synthesized for the first time, where oxygen atoms in the zeolite frameworks are partially replaced by methylene groups using methylene-bridged bis[triethoxysilyl]methane (BTESM) as a unique silicon source. The phases were examined by powder X-ray diffraction and the presence of ∼1.5 wt.% carbon within the framework has been disclosed through 29Si magic-angle spinning (MAS) NMR, FTIR and C elemental analysis. Another indirect proof of the insertion of organic groups in the framework is provided by the more pronounced hydrophobic character of ZOF-X compared to the conventional LSX zeolite, as revealed by thermogravimetry. The ZOF-X materials present the conventional morphology and microporous textural properties of zeolitic materials. Some terminal Si–CH3 groups were revealed by FTIR spectroscopy. The present study showed that the synthesis of methylene-bridged zeolite framework is quite sensitive to many parameters such as the crystallization conditions (temperature and time), the ageing conditions (time, temperature, static or stirring and open or closed system) as well as the batch composition, in particular to the water content. The formation of the organozeolite structure ZOF-X takes much longer time compared with that of their inorganic counterparts.