Synthesis of High-Silica LTA and UFI Zeolites and NH₃–SCR Performance of Their Copper-Exchanged Form

Abstract

A series of LTA zeolites with Si/Al = 8.3-∞ and a UFI zeolite with Si/Al = 11 are synthesized using benzylimidazolium-based cations as organic structure-directing agents in fluoride media, if required, together with the tetramethylammonium ion. Two LTA zeolites with Si/Al = 11 and 16 showed an enhanced operating temperature window with excellent thermal durability for selective catalytic reduction of NOx with NH3, compared to Cu-SSZ-13 commercially being used for automotive applications.