Egenskaper för molekylsikt

Molekylsiktar have strong hygroscopic capacity, so they are used for gas purification. When they are stored, they should not be directly exposed to the air. Molecular sieves that have been stored for a long time and have been hygroscopic should be regenerated before use. When using molecular sieve, try to avoid contact with oil and liquid water.

In industrial production, the drying gases include air, hydrogen, oxygen, nitrogen, argon, etc. Two adsorption dryers are connected in parallel, one works, and the other can be regenerated at the same time. Work and regenerate alternately to ensure the continuous operation of the equipment. The dryer works at 8-12 ℃ and regenerates after being heated to 350 ℃. The regeneration temperature of molecular sieves with different specifications is slightly different. Molecular sieves have good catalytic activity for some organic gas phase reactions.

Också känd som vesicle or zeolite, it is a crystalline aluminosilicate. Its crystal structure has regular and uniform pore diameter, and the pore diameter is the order of magnitude of molecular size. It only allows molecules with smaller diameter than pore diameter to enter, so the molecules in the mixture can be screened according to the size. So it is called molecular sieve.

Crystal Structure of Zeolite A, X and Y

(a) zeolite A ; (b) zeolite X and Y

As early as more than 200 years ago, B. klonstet was the first to name aluminosilicate as zeolite. The general formula of chemical composition is that m and N are metal ions and their valence numbers; X is the molecular number of silica; Y is the molecular number of water; P is the atomic number of aluminum; Q is the number of atoms in silicon. Molecular sieves are used as solid adsorbents in chemical industry. The adsorbed materials can be desorbed, and molecular sieves can be regenerated after use. It is also used for drying, purification, separation and recovery of gases and liquids. Since 1960s, it has been used as cracking catalyst in petroleum refining industry. Now a variety of molecular sieve catalysts suitable for different catalytic processes have been developed.

Adsorbent för molekylsikt