High silica zeolite Phi, a CHA type zeolite with ABC-D6R stacking faults

Abstract The crystallization of alumino-silicate zeolites of CHA structure in the system Na 2 O-K 2 O-Al 2 O 3 -SiO 2 -H 2 O is kinetically controlled, and occurs only in very narrow windows of compositions and hydrothermal conditions. This paper elaborates a new method to synthesize CHA zeolites with Si/Al ratios in a wide range, by means of adding some weak bases to modify the crystallization kinetics in favor of the desired CHA framework. A number of organic and inorganic bases are feasible for this purpose. Pure crystalline CHA materials with Si/Al = 2–30 have been obtained. These weak bases, either organic or inorganic, are not “templates”, nor “structure-directing agents”. The powder XRD patterns of obtained CHA type materials feature both broad and narrow peaks. And additional peaks that belong to low symmetry structures appear. These observations are in coincidence with earlier reported zeolite Phi, indicating existences of stacking faults in the ABC-D6R sequences.