The conversion of the alkali‐treated intergrowth germanosilicate CIT‐13 into the single‐crystalline high‐silica ECNU‐21 (named after East China Normal University) zeolite, with a novel topology and a highly crystalline zeolite framework, has been realized through a creative top‐down strategy involving a mild alkaline‐induced multistep process consisting of structural degradation and reconstruction. Instead of acid treatment, hydrolysis in aqueous ammonia solution not only readily cleaved the chemically weak Ge(Si)−O−Ge bonds located within the interlayer double four ring (D4R) units of CIT‐13, but also cleaved the metastable Si−O−Si bonds therein. This led to extensive removal of the D4R units, and also generated silanol groups on adjacent silica‐rich layers, which then condensed to form a novel daughter structure upon calcination. Individual oxygen bridges in the reassembled ECNU‐21 replaced the germanium‐rich D4R units in CIT‐13, thereby eliminating the original intergrowth phenomenon along the b axis. With an ordered crystalline structure of 10‐ring (R) channels as well as suitable germanium‐related Lewis acid sites, ECNU‐21 serves as a stable solid Lewis acid catalyst for the shape‐selective hydration of ethylene oxide (EO) to ethylene glycol (EG) at greatly reduced H2O/EO ratios and reaction temperature in comparison with the noncatalytic industrial process.

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Zeolites, a class of crystalline microporous materials, have a wide range of practical applications, in particular serving as key catalysts in petrochemical and fine-chemical processes. Millions of zeolite topologies are theoretically possible. However, to date, only 235 frameworks with various tetrahedral element compositions have been discovered in nature or artificially synthesized, among which approximately 50 topologies are available in pure-silica forms. Germanosilicates are becoming an important zeolite family, with a rapidly increasing number of topological structures having unusual double four-membered ring (D4R) building units and large-pore or extra-large-pore systems. The synthesis of their high-silica analogues with higher (hydro)thermal stability remains a great challenge, because the formation of siliceous D4R units is kinetically and thermodynamically unfavorable in hydrothermal systems. Herein, it is demonstrated that such D4R-containing high-silica zeolites with unexpected crystalline topologies (ECNU-24-RC and IM-20-RC) are readily constructed by a versatile route. This strategy provides new opportunities for the synthesis of high-silica zeolite catalysts that are hardly obtainable by conventional hydrothermal synthesis and may also facilitate a breakthrough in increasing the number and types of zeolite materials with practical applications.

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Feasible strategies are desirable for preparing zeolitic nanosheets with opener porosities and more accessible active sites. Highly delaminated FER nanosheets (ECNU-17) with unit-cell scale thickness were hydrothermally synthesized using a simple, small, and low-cost imidazole molecule as the sole organic structure-directing agent (OSDA). The single OSDA directed the formation of the FER framework, while the π−π stacked OSDAs terminated the growth perpendicular to the zeolite sheets. The ECNU-17 nanosheet is only 2.9 nm in thickness, corresponding to one and a half FER unit cells along a-axis. With open hierarchical porosity and an enhanced external surface area of 253 m 2 g −1 , ECNU-17 is endowed with improved mass transport and a significantly increased number of active acid sites accessible to bulky organic molecules. The ultrathin sheets of ECNU-17 aluminosilicate display excellent activity and selectivity for the protection reaction of benzaldehyde with pentaerythritol as well as the cracking of 1,3,5-triisopropylbenzene.