Template-Framework Interactions in Tetraethylammonium-Directed Zeolite Synthesis

Zeolites, having widespread applications in chemical industries, are often synthesized using organic templates. These can be cost-prohibitive, motivating investigations into their role in promoting crystallization. Herein, the relationship between framework structure, chemical composition, synthesis conditions and the conformation of the occluded, economical template tetraethylammonium (TEA(+)) has been systematically examined by experimental and computational means. The results show two distinct regimes of occluded conformer tendencies: 1)In frameworks with a large stabilization energy difference, only a single conformer was found (BEA, LTA and MFI). 2)In the frameworks with small stabilization energy differences (AEI, AFI, CHA and MOR), less than the interconversion of TEA(+) in solution, a heteroatom-dependent (Al, B, Co, Mn, Ti, Zn) distribution of conformers was observed. These findings demonstrate that host-guest chemistry principles, including electrostatic interactions and coordination chemistry, are as important as ideal pore-filling.