The four characteristics of zeolite

Zeolites have superior adsorption, ion exchange, catalytic and stabilization properties.

1.1 Adsorption properties

When the water in the zeolite structure is removed. The pores with large inner surface are formed. It can adsorb and store a large number of molecules. Therefore, the adsorption capacity of zeolite far exceeds that of other substances; the size of zeolite pores and pore channels is uniform and fixed, and the size of ordinary molecules is comparable 

So it has selective adsorption and sieving molecular properties; zeolite has high affinity for H0, NH3, H2S, CO2 and other polar molecules under the joint action of dispersion force and electrostatic force, and has efficient adsorption performance. Due to the electrostatic force, zeolite has preferential selective adsorption for polar and unsaturated polarized molecules.

1.2 Ion exchange properties

The most basic structural units in zeolite space are the silicon-oxygen (SiO) tetrahedra and the aluminum-oxygen fAl04) tetrahedra. The valence electron of one of the oxygen atoms is not neutralized. The entire aluminum-oxygen tetrahedron has a negative charge. In order to maintain electrical neutrality. However, the Na~ and other metal cations in the zeolite are rather weakly combined with the silica-alumina oxygen backbone, and the cations entering the zeolite surface are exchanged with the cations in the zeolite lattice, such as Na+ and so on, usually in the order of cation exchange for plagioclase zeolites: Cs>Rb>NH4+>NH4+. Rb>NH4+>K+>NaLi>BaSr3>Ca>Mg2

Conventional strong acidic resin cation selection order: Fe3'>Ca2+>Mg2'>K+>NH+>Na+>H+>Li+. After exchange, the zeolite structure is not destroyed and can be regenerated. The reaction mechanism can be expressed by the following reaction equation (NH4~ ion as an example1: ammonia removal mechanism: Z-Na++NHZ-NH4~+Na where z represents zeolite skeleton

1.3 Catalytic performance

Zeolite has good catalytic properties． It is an effective catalyst and catalyst carrier. Many of the reactions catalyzed by zeolites belong to the positive carbon ion type one after the positive carbon ion intermediate occurs. Including catalytic cracking, isomerization, alkylation and other reactions, mainly used in the petrochemical field. The zeolite is used as a carrier. Loaded with catalytic metal, it can show better catalytic activity. For example, photocatalysts prepared by using zeolite as a carrier loaded with TiO in photocatalysis. 

The reason why zeolite can be a catalyst or catalytic carrier is mainly related to the acidic position in the zeolite structure, the pore size and the cation exchange properties. Many catalytically active metal ions can enter the pores of zeolite through ion exchange. Subsequent reduction to the elemental state or conversion to a catalytically active compound. Due to the extremely high dispersion state. Not only improve the efficiency of metal utilization． And improve the anti-poisoning effect. Thus, the catalytic performance of zeolite is improved.

1.4 Stability performance

Natural zeolites such as plagioclase, smectite, rhodochrosite, grossular zeolite, etc. have good acid resistance and thermal stability. The thermal stability of natural zeolite depends on the ratio of silicon to aluminum and balanced cations of zeolite. Generally, it is within the range of its composition. The higher the silicon content, the better the stability.