Molecular Sieve

adsorbents are capable of acting as a sieve in the separation of different types of molecules. They are also referred to as 'synthetic zeolite', 'sorbent', and 'adsorbent'.Molecular sieves or zeolites, Clays, Silica Gel and Activated Alumina work well as industrial adsorbents because they have a system of pores or cavities, which creates a great deal of internal surface area, for the separation of molecules, and gases.

Silica Gel, Activated Alumina and Activated (Carbon)Charcoal

have an irregular crystal-like structure, and they are differentiated by varied absorbency. The distribution of openings relative to diameters of adsorbed particles can go from fine to broad. In contrast, Molecular Sieves or Zeolites have uniform openings, the size of which is clearly defined by the construction of the elementary structure of the crystal. All the pores are unable to adsorb molecules, the size of which exceeds the diameter of the pores. The size of the pores in this cage like structure can be precisely controlled through ion exchange to Potassium Aluminosilicate (3a), Sodium Aluminosilicate (4a) or Calcium Aluminosilicate (5a).

Currently it is known that the most powerful molecular sieve effects are attained by dehydrated zeolite crystals. Due to their system of channels or cavities, these adsorbents possess a well-developed internal surface area, accessible to adsorbent molecules. In addition, the proportion of external surface of zeolite (molecular sieve) comprises only a very small part of the total surface.

Zeolites (molecular sieves)

demonstrate a degree of selectivity with regard to different types of molecules and the molecular sieve (zeolite) activity can be expressed at varying degrees. In the case of a complete molecular sieve (zeolite) activity effect, certain molecules diffuse within the crystal, while the diffusion of other molecules is excluded.

Zeolites (molecular sieves) now are used not only in adsorption, but in other very diverse areas of chemistry, for example in catalysis and ion exchange. As before, they are still referred to as 'molecular sieves', although this term suggests many other areas of use of zeolites, and does not reflect, in particular, the well-known property of zeolites to display sieve effects in catalytic and ion exchange reactions.