Targeted Synthesis of Ultrastable High-Silica RHO Zeolite Through Alkali Metal-Crown Ether Interaction

High-silica RHO zeolite was directly synthesized using an alkali metal-crown ether (AMCE) complex as organic structure-directing agent (OSDA). Derived from the UV-vis spectra and zeolite patterns, the crown ethercesium cation interaction was found to have crucial effect on the enhancement of silica content within the zeolite framework. The synthesized RHO zeolites possess up to four times larger silica/alumina ratio (SAR) values than that in their conventional form, which gives them extraordinarily rigid frameworks even after hydrothermal aging under 800 degrees C. Compared to commercial zeolites, copperexchanged high-silica RHO zeolites demonstrate considerably high reaction activity in NOX removal, making them promising candidates for diesel exhaust treatment.