(196f) Data-Driven SDA Design and High-Throughput Experimentation for the Synthesis of High-Silica Small-Pore Zeolites Containing Lta Cavities

Small‑pore zeolites containing lta cavities—LTA, UFI, RHO and KFI frameworks—feature three-dimensional cage networks for shape‑selective catalysis, adsorption and separation. However, hydroxide‑mediated syntheses targeting these frameworks typically yield low Si/Al ratios, unwanted mixed phases, and limited thermal stability, restricting their practical use. To address these challenges, we employed high‑throughput screening to identify the optimal combination of organic structure‑directing agents (OSDAs) and inorganic cations that can stabilize each building unit inside the frameworks and expand the synthesis window for phase‑pure, high‑silica materials.

Here, we introduce a dual‑templating approach that combines an optimal OSDA, chosen for its templating energy and shape complementarity. Specific pairs of subsidiary cations were identified by SHAP analysis for their stabilizing influence on the framework. Density functional theory calculations confirm that these cations stabilize the key building units in each framework. Guided by these insights, gel composition, pH, crystallization temperature and time were systematically optimized to yield phase-pure catalysts. Samples were characterized by powder X‑ray diffraction, nitrogen adsorption–desorption isotherms, scanning electron microscopy and ICP‑AES. Hydrothermal resilience was assessed by steaming at 750 °C for 12 hours with 10 v/v% of steam flowing balanced with air.

The synthesized LTA, UFI, RHO, and KFI zeolites achieve record-high Si/Al ratios for hydroxide‑mediated syntheses and retain crystallinity after high‑temperature steaming, surpassing the previously reported hydrothermal stability under identical conditions. These results demonstrate that rational OSDA selection with tailored ionic environments can broaden the synthesis window of lta‑containing zeolites. This approach can pave a way to design microporous materials with precise pore architectures and site distributions for applications such as deNOx reactions.