Designed synthesis of STA-30: a small pore zeolite catalyst with topology type SWY

Small-pore aluminosilicate zeolites are attractive targets for synthesis because of their activity as catalysts in important reactions, including ammonia-mediated selective catalytic reduction (SCR) of NO_x in auto-exhaust emissions. Such a zeolite with SWY framework type, previously observed as a silicoaluminophosphate, has been prepared with high crystallinity via designed syntheses employing organic 1,8-(1,4-diazabicyclo[2.2.2]octane)octyl (diDABCO-C8) and K⁺ cations as templates. STA-30 (St Andrews microporous material 30) is an ABC-6 structure in the erionite-offretite family of zeolites that exhibits the 12-layer stacking sequence AABAABAACAAC. The framework, which can be prepared with a controllable Si/Al ratio, possesses columns of alternating d6r units and can cages, of which the latter are oriented to give an inter-column pore space comprising gme cages and swy cages connected via 8Rs. DiDABCO-C8 cations fill the swy cages of as-prepared STA-30, while K⁺ cations display high occupancy in the can cages. Removal of the template by calcination, followed by ammonium ion exchange of K⁺ cations residing outside the can cages and subsequent deammoniation, gives a highly crystalline zeolite (K₃H₆Al₉Si₇₂O₁₄₄, P6₃/mmc, a = 12.9922(9) Å, c = 29.9624(12) Å) with solid acidity shown by solid-state ¹H MAS NMR. Upon hydration, a portion of the Al adopts octahedral geometry, as demonstrated by two sharp resonances at −2.0 and −3.1 ppm in the ²⁷Al MAS NMR. These octahedral species can be converted back to tetrahedral Al by ammonium exchange and are interpreted as distinct hydrated framework Al sites. The activated K,H-STA-30 is a small-pore solid acid with a three-dimensionally connected micropore volume of 0.31 cm³ g^–1. In the copper-loaded form, it is an active catalyst for the SCR of NO by ammonia.