The molecular sieve is a kind of the crystal aluminosilicate. Because there are even pore size and much higher specific surface areas, there are many of the excellent merits. (1) The selective absorption as the different size and shape of molecules, that is to say, it only absorbs those molecules of which the diameter is less than the pore size of molecular sieve. (2) To those smaller polar molecules and the unsaturated molecules, it has the property of selective absorption. The bigger the polarity is, and the higher the instauration is, the stronger property of the selective absorption is. (3) It has much stronger property of water sorption too. No matter in the situations of higher temperature, larger space velocity, or lower content of water it is, there is rather higher capacity of water sorption.
Now, there are many types of the molecular sieve, such as 3A, 4A, 5A, 10X, 13X, and Cu2+ etc., which can be produced by our company and applied to the industries.
1. 3Amolecular sieve
a) Introduction
In general, there contains water of 400－700PPm in the hydrolysis gas, it can ice during the operation of cryogenic separation. In addition, it may produce the white crystal compounds of water-hydrocarbon under the high pressure and low temperature, for instance, CH4, C2H6 and C3H8 etc. However, the ice and the compounds of water and hydrocarbon can induce the breakage of the pipes and blockage of the equipments, even to cause the stopping. Therefore, the petroleum hydrolysis gas should be carrying out the deep dehydrogenation before the cryogenic separation , and the content of water should be below to 5PPm ( Its dew point is less than 60℃). Nowadays, it is the most ideal deep drying absorbing agent, which is broadly approved and adopted in our country or abroad. Because it absorbs the moisture in the hydrolysis gas only and not absorb the bigger hydrocarbon molecules, such as, C2H6, C2H4, C3H8 and C3H6 etc. This can avoid the coking of the olefin molecules in the pores of molecular sieve, and prolong the serviceable lifetime of absorbing agents.