Zeolites are porous crystalline aluminosilicate materials constructed from linked TO₄ tetrahedra (T= Al³⁺ or Si⁴⁺), joined through shared oxygen atoms, forming a three-dimensional framework that defines a regular system of voids and channels of molecular dimensions. They are often called molecular sieves because of their ability to distinguish different molecules due to their size, shape, or polarity. In addition, they are also thermally and chemically stable materials, thus they can be used in variety of thermochemical environments. Due to their unique physicochemical properties described above, they have found many applications as catalysts, sorbents, water softeners etc

Figure 1 Schematic of the faujasite microstructure. (SI, SI’, SII, SII’, SIII, are extra-framework cation positions present in faujasite-type zeolites)

A schematic diagram of the faujasite microstructure is shown in Figure 1. Each corner of the framework represents a Si or Al atom and each line a bridging oxygen atom. Faujasite crystals have cages with diameters of approximately 1.3 nm, which are interconnected through openings with sizes of approximately 0.74 nm.