Skeleton Components Of Molecular Sieves

Molecular sieve is an aluminosilicate inorganic compound that can withstand high temperatures and has good thermal stability. It is easy to regenerate and can be reused many times. The skeleton will not be broken down by microorganisms, etc. The main components of molecular sieves are siloxane tetrahedra and aluminum-oxygen tetrahedral. Since the valence of aluminium is 3, the valence of the oxygen atom in the aluminum-oxygen tetrahedron AlO4 is unbalanced, thus making the whole aluminum-oxygen tetrahedral band negatively charged. To maintain electrical neutrality, there must be positively charged metal ions in the vicinity of the aluminum-oxygen tetrahedron to cancel out its negative charge. A strong electric field is generated between the positively charged metal ions and the negatively charged zeolite backbone, which has a huge impact on the adsorption performance of the zeolite. The adsorption capacity of molecular sieves for polar substances is much stronger than that of non-polar substances. At the same time, species containing double or large π bonds also have considerable adsorption capacity by inducing polarization due to the strong electric field. In general, the more charge a cation carries, the smaller the ionic radius, the stronger the electric field generated, the greater the induction of double bonds, and the greater the adsorption capacity of these species. For example, molecular sieves are capable of adsorbing large amounts of olefins and alkynes, such as ethylene and propylene.