Operando Two-Dimensional Solid-State NMR Unveils Dual-Template Collaboration and Competition in SAPO-34 Zeolite Crystallization

Unraveling the mechanism of zeolite crystallization, especially in a complex system containing dual-template agents, remains a critical challenge. In this work, we introduced, for the first time, novel operando two-dimensional (2D) solid-state NMR spectroscopy under extreme conditions of high temperature and high pressure, allowing for observations with atomic-level spatial and temporal resolution, thereby enabling unprecedented insights into the crystallization of SAPO-34 zeolite. By utilizing operando 2D ³¹P{¹H} HETCOR, ²⁷Al{¹H} HMQC NMR techniques, we clarified the intricate cooperative and competitive interactions of dual-template agents and highlighted the synergistic effect between templates and hydroxyl groups during CHA zeolite crystallization. Furthermore, operando ¹H, ²⁷Al, and ³¹P MAS NMR revealed a previously unreported induction period, which precedes intermediate formation. This innovative approach advances the understanding of molecular dynamics, crystallization mechanism, and synthesis method for zeolites, representing a significant leap forward in the field of operando two-dimensional solid-state NMR spectroscopy.