The synthesis of chabazite with high solid yields is achieved by the rational combination of directing effects of a source of Si and Al coming from USY zeolites and the inexpensive tetraethylammonium.

The use of small pore zeolites with large cavities has been reported for relevant applications in catalysis or gas separation.[1] One of the most important applications of these materials as catalysts is the selective catalytic reduction (SCR) of nitrogen oxides (NO x ), where copper-containing zeolites with small pore sizes show excellent activities to remove these hazardous compounds produced during combustion in diesel engines. [1,2] Interestingly, these small-pore zeolites show higher hydrothermal stability compared to other zeolitic materials presenting larger pore sizes, such as Cu-ZSM-5 or Cu-Beta. [3] The particular stabilization of the Cu 2+ cations within the double 6-rings (D6Rs) present in some structures of these small pore zeolites, i.e. chabazite (CHA structure), has been claimed as a plausible reason for their higher hydrothermal stability.[4]Another zeolite with related structural properties to chabazite is SSZ-39 (AEI structure), which is an aluminosilicate with large cages connected by a three-directional small 8-ring (8-R) pore system, and also with D6R as secondary building units in its structure.[5]Recently, we have reported that Cu-exchanged SSZ-39 zeolite is an active and hydrothermally stable catalyst for the SCR of NO x with ammonia, showing even better catalytic performance than Cu-exchanged CHA.[6]The preferred synthesis procedure of SSZ-39 requires the use of simple alkylsubstituted cyclic quaternary ammonium cations as organic structure directing agents (OSDAs) in alkaline conditions. [7] These organic cations could be easily prepared from commercially-available pyridine precursors, [8] making attractive the use of these OSDAs for the synthesis of the SSZ-39 from an economic point of view. Unfortunately, this methodology can afford the preparation of the SSZ-39 in low solid yields (lower than 50%), since the final crystalline solids show much lower Si/Al ratios than the Si/Al ratios initially introduced in the synthesis gels, [6,7,8] indicating that most of the Si species remain in solution after the crystallization procedure. This fact limits the potential use of SSZ-39 in commercial applications.Recently, the synthesis of the high silica AEI zeolite with high solid yields (above 80%) has been reported using USY zeolite as silicon source and tetraethylphosphonium (TEP)cations as OSDA. [9] Although this achievement is highly relevant in terms of the optimization of the SSZ-39 synthesis, the use of P-based OSDAs still presents some 3 important drawbacks. On one hand, phosphine-derived organic molecules show important environmental and health hazards, and, on the other hand, the complete removal of the phosphorous-species entrapped within the zeolitic cavities is very difficult, especially within small pore zeolites, and their calcination process requires high temperatures and hydrogen atmospheres for the complete decomposition/elimination of these compounds.[9]It is worth mentioning that in the last years the use of pre-formed crystalline zeolitic precursors to synthesize different...