Two-Dimensional Zeolites: Current Status and Perspectives

Zeolites are well-known as valuable crystalline solids with framework structures containing discrete micropores of molecular dimensions that accommodate exchangeable extra-framework cation sites. Lamellar zeolites combine useful benefits of both classes, high catalytic activity, microporosity, thermal stability, and chemical resistance of zeolites with structural flexibility of 2D solids, enabling their postsynthetic modification, both structural and compositional. The main category of 2D zeolites is the layered precursors, which are viewed as primary forms because they are the starting materials for further modifications. The various modifications may be an end product (IEZ-stabilized) or they may be further modifiable, like intercalated and swollen derivatives. Synthesis method, either via direct synthesis or by postsynthetic modification, is another criterion for classifying layered zeolite materials. New precursors can also be obtained from a regular zeolite by selective chemical degradation.