Molecular sieves are a class of crystalline aluminosilicates and are a new type of multifunctional. It has the characteristics of uniform pore size and extremely 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, insulating glass desiccant, molecular sieves for air separation, and oxygen-enriched molecular sieves. The advantages of molecular sieves: Selective adsorption according to the size and shape of the molecules, that is, only those molecules smaller than the pore size of the molecular sieve are adsorbed. For small polar molecules and unsaturated molecules, it has selective adsorption performance. The greater the polarity and the higher the degree of unsaturation, the stronger the selective adsorption. Has strong water absorption. Even at higher temperature, higher air velocity and lower water content, there is still a considerable water absorption capacity. The characteristic molecular sieve of molecular sieve is an artificial crystalline aluminosilicate, which adsorbs or repels molecules of different substances according to the size of the pores inside the crystal, so it is vividly called 'molecular sieve'. It consists of AlO4 and SiO4 tetrahedra, and in the molecular sieve lattice, metal cations play the role of balancing excess negative charges in the AlO4 tetrahedra. Substances whose molecular diameter is smaller than the pore diameter of the molecular sieve crystal can enter the molecular sieve crystal and thus can be adsorbed, otherwise they are repelled. Molecular sieves in turn prioritize the order of adsorption according to the polarity or polarizability of different substances. Generally, molecules with strong polarity are easily adsorbed. Molecular sieves have good thermal stability and can withstand short-term high temperatures of 600 degrees Celsius to 700 degrees Celsius. Molecular sieves are insoluble in water, but soluble in strong acids and alkalis, so they can be used in PH5-11 media and exchangeable in salt solutions. other cations. Molecular sieves have unique properties: 1. Reversible adsorption to water, gas and liquid 2. Exchange characteristics of cations 3. The pores of molecular sieves have a very high internal surface area. Compared with other adsorbents, molecular sieves have outstanding characteristics: 1. Very high adsorption capacity 2. Selective adsorption and separation 3. Catalytic properties 4. Use of ion-exchange molecular sieves The characteristics of zeolite molecular sieves make them widely used in petrochemicals, natural gas, Frozen, food and other fields. The main application areas are: 1. Drying of gases and liquids; 2. Purification of gases and liquids; 3. Separation of gases and liquids; 4. Hydrocracking, catalytic cracking and isomerization catalysts; 5. Washing aids and soft water agent