ITQ-54: a multi-dimensional extra-large pore zeolite with 20 x 14 x 12-ring channels

A multi-dimensional extra-large pore silicogermanate zeolite, named ITQ-54, has been synthesised by in situ decomposition of the N,N-dicyclohexylisoindolinium cation into the N-cyclohexylisoindolinium cation. Its structure was solved by 3D rotation electron diffraction (RED) from crystals of ca. 1 mu m in size. The structure of ITQ-54 contains straight intersecting 20 x 14 x 12-ring channels along the three crystallographic axes and it is one of the few zeolites with extra- large channels in more than one direction. ITQ-54 has a framework density of 11.1 T atoms per 1000 A(3), which is one of the lowest among the known zeolites. ITQ-54 was obtained together with GeO2 as an impurity. A heavy liquid separation method was developed and successfully applied to remove this impurity from the zeolite. ITQ-54 is stable up to 600 degrees C and exhibits permanent porosity. The structure was further refined using powder X-ray diffraction (PXRD) data for both as-made and calcined samples.