Molecular sieve is a good sorbent of moisture, so it should be kept in dry place and avoid the exposition in the air. Before use, molecular sieve should be processed by regeneration because the molecular sieve may contains oil and liquid water, which will block the microcellular structure of molecular sieve. The oil in molecular sieve may be carbonized and produce carbon to block the holes of molecular sieve. When liquid water contacts with molecular sieve, it may releases a plenty of heat in very short time, which may happens dangerous accident or destroys the performance of molecular sieve. When molecular sieve in pressure container is regenerated, the pressure of tower should be lower down slowly, or it may causes the pulverization of molecular sieve. High temperature is good for the regeneration of molecular sieve, but it will cost a lot of energy and reduce the life of molecular sieve; therefore its regeneration temperature should be 200-350°C and do not exceed 600°C.   1. 3A molecular sieve is mainly applied to absorb water molecular in drying natural gas and oil gases, especially in drying Catalystic Splitting Decomposition Oil gases and Alkene. So it is usually used as fine drying agent in medicine, food, glass industry and so on.   2. 4A molecular sieve is mainly used to make static dehydration in airtight gas or liquid system, it can remove the moleculars of ethyl alcohol, hydrogen sulphide, carbon dioxide, ethylene, acrylica, and also dry the alkane.   3. 5A molecular sieve is mainly applied to separate isomerism alkane. Meanwhile, it can also absorb the moleculars which can pass through in 3A and 4A molecular sieve and whose diameters are less than five angstrom. Especially the result is very evident in the changing pressure absorption system.             4. 13X molecualr sieve can absorb the moleculars which can pass through in 3A,4A and 5A molecular sieve and whose critical diameters are very large, such as hydrocarbon and isomerism alkane separation.