CIT‐9: A Fault‐Free Gmelinite Zeolite

Abstract A synthetic, fault‐free gmelinite (GME) zeolite is prepared using a specific organic structure‐directing agent (OSDA), cis‐3,5‐dimethylpiperidinium. The cis‐isomers align in the main 12‐membered ring (MR) channel of GME. Trans‐isomer OSDA leads to the small‐pore zeolite SSZ‐39 with the OSDA in its cages. Data from N2‐physisorption and rotation electron diffraction provide evidence for the openness of the 12 MR channel in the GME 12×8×8 pore architecture and the absence of stacking faults, respectively. CIT‐9 is hydrothermally stable when K+‐exchanged, while in the absence of exchange, the material transforms into an aluminous AFI‐zeolite. The process of this phase‐change was followed by in situ variable temperature powder X‐ray diffraction. CIT‐9 has the highest Si/Al ratio reported for GME, and along with its good porosity, opens the possibility of using GME in a variety of app…