(289d) Investigation of a Liquid-Mediated Defect-Healing Treatment in Zeolite Beta

High hydrothermal stability is crucial for many applications of zeolites, including automotive emission abatement and fluid catalytic cracking. However, silanol defects can reduce the hydrothermal stability of a zeolite. Recently, Iyoki et al.¹ reported a hydrothermal liquid-mediated defect-healing treatment based on tetraethylammonium (TEA⁺) hydroxide and ammonium fluoride and demonstrated dramatic enhancements of hydrothermal stability in high-silica zeolites. However, many aspects of the mechanism remain unclear. Here, the application of this treatment, and variants thereof, to zeolite beta are reported. Through comparison between H-beta of high (730) and lower (28.6) SiO₂/Al₂O₃, characterisation of the treated samples and variation of conditions and reagents, insights into the interaction of TEA⁺ and F^- with H-beta under hydrothermal conditions was gained.

References

1. Iyoki, K.; Kikumasa, K.; Onishi, T.; Yonezawa, Y.; Chokkalingam, A.; Yanaba, Y.; Matsumoto, T.; Osuga, R.; Elangovan, S. P.; Kondo, J. N.; Endo, A.; Okubo, T.; Wakihara, T., J. Am. Chem. Soc. 2020, 142 (8), 3931–3938.