Molecular sieve is a microporous crystal of aluminosilicate, which has the characteristics of uniform pore size, high specific surface area, good thermal stability, strong adsorption performance, large internal surface area, and high strength. Due to their different uses, molecular sieves are divided into 3A, 4A, 5A, 13X, 13X APG, 13X HP, CaX, Li-X, carbon molecular sieves, etc.