X and Y-type zeolite is wider application of two kinds of zeolite

X and Y-type dehydration of natural gas is used widely two zeolites, they all belong to the faujasite type, its crystal structure is identical, the difference lies in Al ratio (SiO2 / Al203) are different. While the unit cell contains 192 silicoaluminophosphate atoms, but Y-type silicon content is higher, closer to faujasite. Precisely because of the different silica to alumina ratio of these two types of molecular sieves are the difference in acid resistance, thermal stability and so on. 
Faujasite-type crystal structure similar to that of diamond structure. Diamond crystals are composed of carbon atoms, it has four chemical bonds of carbon atoms in space at an angle to each other (about 109.), a chemical bond between the carbon atoms are connected to each other. In terms of cutting angle octahedral (ie β cages) instead of diamond crystals all the carbon atoms between adjacent β cage by six-membered rings are interconnected by six oxygen bridge (chamfered octahedron has eight six-membered ring, only use one of the four, and one by one, to connect with each other across). Faujasite structure is so connected together, that is, the crystal structure of X-type and Y-type molecule. 
And A-type zeolite as described above when the β cages connected to each other, but also the formation of two new cages, the cage is a cage when two β through six-membered rings are interconnected by an oxygen bridge formed, which cage is actually a hexagonal prism, hexagonal column called cage, the volume of hexagonal pillar cage cages smaller than β; another new cage called "faujasite cage", which is surrounded by a hexagonal columnar β cages and cage made. Faujasite cage by eighteen four rings, four six rings and four twelve ring posed. Faujasite cage and faujasite cage through twelve ring communication, its volume is much greater than β cages, cavity volume of 850 Å 3 and an average diameter of 12.5 Å. 
Faujasite cage is the main hole X and Y type zeolite, through six-membered ring or a four-membered ring and a cage surrounding the β communication, connected by four-membered ring and a cage surrounding the hexagonal column, more importantly twelve by four adjacent ring and around the other four interlinked faujasite cage. Twelve-membered ring diameter is 8-9 angstroms, is the main channel X and Y-type zeolite. 
X and Y type zeolite unit cell contains 192 silica (including aluminum oxide) tetrahedron, the equivalent of eight β cages. Typical X-type zeolite 13x unit cell formula 
Na86 [(AlO2) 86 (SiO2) 106] • 264H20 
Indeed Depending SiO2 / Al203 ratio of the unit cell formula is also a difference. Typical Y zeolite unit cell formula 
Na56 [(AlO2) 56 (SiO2) 136] • 264H20 
Faujasite zeolite cations often distributed in a predetermined position, the position of some commonly used symbols. For sodium faujasite type, the cations have three positions (SI, SII, SIII), SI cage located hexagonal columns, each cell has 16 positions; β cages located near the SII six-membered ring, each crystal Cellular has 32 ​​positions; SIII is located on a four-membered ring β cages, each cell has 48 locations. 
In the process of exchange of sodium ions in the faujasite with other metal ions found more cationic distribution locations, which are generally in the cubic unit cell diagonal to S1, S2, S3, S4, S5 private U and other symbols. Table 1 lists the names and numbers of these locations. 
It should be noted, these six cation distribution location above three cation is not entirely correspond to the distribution location. Due to the location of the different metal ions in the crystal, its performance is also different.