What are the properties of zeolite molecular sieve

Adsorption properties

Adsorption of zeolite molecular sieve is a physical change process. The reason for adsorption is mainly a molecular gravitational force on the surface of the solid "surface force", when the fluid flow, some molecules in the fluid due to irregular movement and collision to the surface of the adsorbent, molecular concentration on the surface, so that the number of such molecules in the fluid to reduce the purpose of separation and removal. 

As adsorption does not occur chemical changes, as long as the molecules concentrated on the surface to drive away, zeolite molecular sieve has adsorption capacity again, this process is the reverse process of adsorption, called the resolution or regeneration. Because of the uniform pore size of zeolite molecular sieve, only when the molecular dynamics diameter is smaller than the pore size of zeolite molecular sieve can easily enter the cavity inside and be adsorbed. 

So zeolite molecular sieve for gas and liquid molecules is like a sieve, according to the size of molecules to determine whether to be adsorbed. Because of the strong polarity inside the cavity of zeolite molecular sieve, it can have a strong effect with molecules containing polar groups on the surface of zeolite molecular sieve, or polarize the polarizable molecules through induction to produce strong adsorption. This polar or easily polarizable molecules are easily adsorbed by polar zeolite molecular sieve, which reflects another adsorption selectivity of zeolite molecular sieve.

Ion exchange properties

The commonly used term ion exchange refers to the exchange of compensating cations outside the zeolite molecular sieve skeleton. The compensating ions outside the skeleton of zeolite molecular sieve are generally protons and alkali or alkaline earth metals, which can be easily exchanged into metal ion type zeolite molecular sieve of various valence states by ion exchange in aqueous solutions of metal salts. The ions migrate more easily under certain conditions, such as aqueous solutions or when subjected to higher temperatures.

In aqueous solutions, zeolite molecular sieves can exhibit different ion exchange properties due to the difference in ion selectivity. The hydrothermal ion exchange reaction between metal cations and zeolite molecular sieves is a free diffusion process. The rate of diffusion governs the rate of exchange reaction.

Catalytic properties

Zeolite molecular sieves have a unique regular crystal structure, each of which has a certain size and shape of pore structure and has a large specific surface area. Most zeolite molecular sieves have strong acid centers on the surface, while strong Coulomb fields within the crystal pores act as polarizers. 

These properties make it an excellent performance catalyst. Multiphase catalytic reactions are carried out on solid catalysts, and the catalytic activity is related to the size of the catalyst's crystal pores. When zeolite molecular sieve is used as a catalyst or catalyst carrier, the catalytic reaction is controlled by the size of the zeolite molecular sieve crystalline pores. Both the size and shape of the crystal pores and pore channels can play a selective role in the catalytic reaction. 

Under general reaction conditions zeolite molecular sieves play a dominant role in the reaction direction, presenting shape-selective catalytic properties, a property that makes zeolite molecular sieves powerfully viable as new catalytic materials.