Zeolite X, together with zeolite Y, belongs to the family of aluminosilicate molecular sieves with a faujasite-type structure (FAU). It is characterized by the formula |(Ca, Mg, Na 2) 29 (H 2O) 240|[Al 58Si 134O 384]– FAU (International zeolite association (IZA)). Faujasite is a rare zeolite, although its synthetic counterparts Linde X and Linde Y are largely used as sorbents and catalysts. Zeolite X differs from zeolite Y by its Si/Al atomic ratio which is typically in the range from 1 to 1.5 for the X and higher for the Y-type zeolite. High Si/Al ratio is desirable towards thermal stability, a property that is less favorable to zeolite X. The 24 tetrahedra cuboctahedral units (sodalite cages) in the FAU framework type are arranged in the same way as the carbon atoms in diamond. They are connected via hexagonal prisms (double six rings) forming a three-dimensional porous channel structure along [110], characterized by 12 oxygen ring window openings with the aperture of 8 Å and supercages of...