The molecular sieve is a kind of the aluminoslicam. As there are even pole size and much more specifie surface in int. It has much excellent merits.

1. The selective absoption, according to the size and shape of the absorbed molecule, the higher the polarity or unsaturation is, the stronger selective absorption is.

2. It has the selective abosorption for the polar of unsaturated molecules, the higher the polarity or unsaturation is, the stronger selective absoption is.

3. It has strong water absorption.