Template–Framework Interactions in Tetraethylammonium‐Directed Zeolite Synthesis

Abstract

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.

Synthesis of ultra-small mordenite zeolite nanoparticles

“…The 12 MR large-pores along c-axis were occupied by TEAB molecules as simulated by Weckhuysen and coworkers [20]. It can be deduced that the high concentration of TEAB could generate abundant crystal nuclei resulting in smaller crystals.…”

Machine-learning approach to the design of OSDAs for zeolite beta

“…The fact that ${\text{RMSE}}_{\text{training}+\text{test}}$ and ${\text{RMSE}}_{\text{validation}}$ are very similar indicates that the neural nets are well trained and not overfit to the train and test set. For reference, the tetraethyl amine OSDA has a stabilization energy of −10 kJ/(mol Si) in zeolite beta A (30). Fig.…”

Design of Organic Structure‐Directing Agents for the Controlled Synthesis of Zeolites for Use in Carbon Dioxide/Methane Membrane Separations

“…Of these, four have a predicted stabilization energy below −10 kJ/(mol Si) with two copies in the zeolite, and a predicted stabilization energy about half this value with only one copy, as shown in Table . While stabilization energies cannot be compared across zeolites, only across OSDAs for a given zeolite, we note that the stabilization energies at 2 copies per unit cell in Table are significantly better than the −6.76 kJ/(mol Si) for TEA+ in MFI (Table S3 of) …”

“…While stabilization energies cannot be compared across zeolites, only across OSDAs for a given zeolite, we note that the stabilization energies at 2 copies per unit cell in Table 5 are significantly better than the À 6.76 kJ/(mol Si) for TEA + in MFI (Table S3 of). [39] For the ABW framework, the de novo design algorithm had difficulty to generate high scoring OSDAs, as can be deduced from Table SI4 in the Supporting Information. A run in which 2 copies were fitted into the zeolite unit cell did not generate molecules with stabilization energies below 0 kJ/ (mol Si), e. g. entry ABW2 in Table 2.…”