A new aluminosilicate zeolite, EMM-68, structurally related to the CHA framework used in DeNOx and methanol-to-olefins (MTO) catalysis, has been synthesized using 1,2,3-trimethyl-4,5,6,7-tetrahydrobenzimidazolium as the structure-directing agent (SDA). EMM-68 features a 10 × 8 × 8 channel system and a spacious cavity measuring 8.0 × 9.4 × 7.7 Å, as determined by in-house X-ray diffraction using the FOCUS method. Large and extra-large pore zeolites—defined by channels formed from 12 or more tetrahedral atoms—are critical materials for industrial applications such as shape-selective catalysis, large molecule separation, transalkylation, fluid catalytic cracking (FCC), and hydrocracking of heavy oil fractions. In this study, we report the synthesis of an extra-large pore zeolites: EMM-72 (SFN framework, 6.2 × 8.5 Å), using tetra- and penta-methylbenzimidazolium as the OSDAs. These SDAs are effective across a broad range of aluminosilicate compositions, with Si/Al ratios as low as 15. In EMM-72, the additional methyl group in the SDA enhances fit within the 14-ring pockets, promoting greater molecular spacing in the final framework compared to EMM-57 (DON framework type). By extending benzimidazolium and tetrahydrobenzimidazolium molecules with longer alkyl chains, we successfully synthesized multi-dimensional large-pore zeolites EMM-70, EMM-73, EMM-75, and EMM-76. Stability under hydrothermal conditions and energy optimization calculations highlight the importance of host–guest interactions between SDAs and the zeolite framework in phase selection.

Our results suggest that fused 5- and 6-ring organic compounds are promising SDAs for directing the formation of large and extra-large pore zeolites. These materials will be further explored for catalytic and adsorption applications involving bulky hydrocarbons and shape-selective transformations beyond the limitations of conventional large-pore zeolites.