Molecular sieve is a type of absorbent or thin film of Si,Al,O and other metal cations. Its aperture is similar to common molecule.It separate all kinds of fluid molecules according to this effective micro hole effective aperture. Zeolite molecular sieve is a type of natural and artificial crystalline aluminosilicate.It is widely used in the fields of Petrochemical, Environmental Protection, Bioengineering, Food Industry, Pharmaceutical Chemical Industry etc.

Performance of Zeolite Molecular Sieve

  • Adsorption

Zeolite molecular sieve adsorption is a physical process.The main reason for adsorption is a surface force produced by molecular gravity on solid surface.When the fluid flows, some molecules in the fluid collide with the adsorbent surface due to irregular motion, resulting in molecular concentration on the surface which decreases the content of the relative molecular to get the result of separation and clean.As there is no chemical change, we only need discharge the molecular concentrated on the surface to recover its adsorption. It is the reverse process of adsorption. It is called regeneration.

As the aperture of molecular sieve is uniform, only the molecular smaller than the molecular sieve aperture can get into the molecular sieve bug hole to be adsorbed.So to gas and liquid molecular, the molecular sieve is just like a sieve. The size of the molecular determines whether it can be absorbed by the molecular sieve.The molecular sieve bug hole has strong polarity which can cause strong effects with the molecular of polar group on the surface of the molecular sieve.The performance the the polar or polarizable molecule is absorbed by polar zeolite molecular sieve is another adsorption selection of the molecular sieve

  • Ion Exchange Performance

Normally, the ion exchange is the compensating cation exchange out of the molecular sieve framework. The compensating ion out of the molecular sieve framework is proton and alkali metals or alkaline earth metals generally.They are easily to be exchanged to various metal ionic zeolite molecular sieve.Ion is easily to remove under certain conditions such as aqueous solution or high temperature.In aqueous solution, it has different ion exchange performance because of the difference ion selectivity of the zeolite molecular sieve.

The molecular sieve aperture can be changed through ion exchange. The performance is also be changed to achieve the purse of shape selective absorbing and separating mixture.

  • Catalytic performance

Zeolite molecular sieve has unique structured crystal structure.Each type has certain size and shape of lacuna structure and large specific area. Most of the molecular sieve surface has strong acid center and has strong Coulomb field. All of these characters make it to be a catalyst with excellent performance.

When the zeolite molecular sieve acts as catalyst or catalyst substrate, catalytic reaction is controlled by the crystal pore of the zeolite molecular sieve. The size and shape of crystal pore and lacuna have selective effect to the catalytic reaction.Under general reaction conditions, zeolite molecular sieve has leading roles for the reaction direction.It is its selective catalytic property which make molecular sieve has strong vitality as a new material catalyst.

Application of Zeolite Molecular Sieve

  • Application in Dehydration and Purification

Dehydration

Molecular sieve type A and type X has polar hydrophilic so it is used for air drying. Ethanol is added in to the petrol to instead part of the petrol. As an fuel, the water content in ethanol should be less than 0.8%. If we use distillation to pure the ethanol, we can only get 95% purity.We usually use zeolite molecular sieve 3A to dehydrate ethanol and produce fuel ethanol.

Air Purification

When there is O2, the NO2 formed by O2 and NO can be absorbed on zeolite molecular sieve together with O2. It promote the molecular sieve specially Na type molecular sieve adsorbing NO . Molecular sieve 5A,10X,13X have excellent adsorption ability for formaldehyde.

  • Application in adsorption separation

Separation of mixed xylene

Molecular 13X has excellent separation effect to mexed xylene.

Separation of N2/O2

PSA(Pressure Swing Adsorption) is based on the balance adsorption difference of N2/O2 on surface of zeolite molecular sieve to adsorb N2 selectively. Type A and Type X zeolite molecular sieve has high separation coefficient.

Increasing the content of octane in Petrol

Because the octane of isoalkanes is much higher than that of n-alkanes, absorption separation can desorb n-alkanes. In application, we often used adsorption separation together with C5/C6 alkane isomerization. N-alkanes molecule is less than molecular sieve aperture, so it can get into the molecular sieve and be adsorbed in it. Through this way, we can get material rich in octane isoalkanes.

  • Application in catalysis

Zeolite molecular sieve has complex and variable structures and unique pore system. It is an excellent catalysis

In order to promote the application in adsorption separation and catalysis, we need decrease production cost, study the effect of the structure, composition, performance caused by the synthesis and modification.