Gas purification techniques

Regenerative adsorption zeolite
Zeolite is an aluminum silicate which occurs both natural as produced synthetic. The zeolite have a three-dimensional structure with pores. It exists from silicon, aluminum and oxygen ions. The silicon ions have been neutrally charged in the crystal structure. Aluminum ions creates negative places. To keep the cargo in balance a counter ion is (Na⁺, K⁺) or a proton (H⁺) is present in the pores. One types of zeolite have just as large pores through the entire crystal structure. The crystal structure is stipulated by the ring size of the crystal structure. To change the ratio of aluminum on silicon can also has influence on the pore size as well as the type of counter ion. All natural zeolites contain aluminum and are hydrophilic of nature.
This material forms a good adsorbents for polar substances (for example: water and water soluble substances). By removing aluminum zeolite become hydrophobic and can absorb apolar substances such as VOC. Hydrophobic zeolite can be produced by synthetic under form of crystallization from 1 µm up to 1 mm in diameter. These crystal are tied up to larger grains to reduce the air capacitance of the bed. Because synthetic zeolites are expensive in comparison with natural zeolites they are generally only applied as hydrophobic zeolite or zeolite catalysts. The principle of adsorption like an active carbon is also considered to the zeolite as a bed. In contrast to active cabbage zeolite are not used one-off and are not afterwards destroyed after saturation, but zeolite are used for applications with regeneration of the zeolite. This is blamed to the cost of the zeolite. Zeolite can be obtained with pore sizes of 0.3 - 3 nm. This pore size is uniform for one type zeolite. Zeolite will adsorb no molecules which are larger than the pore size. Also molecules for which are no affinity will not be adsorbed. Figure: zeolite adsorption Zeolite are possible used with active carbon or polymers where the polymer or the active carbon works at the higher concentrations and the zeolite as polishing at the lower concentrations. This can become carried out by making a mixture of adsorbentia several beds after each other or by in one bed. The advantages of zeolite adsorption are: High efficiency of VOC disposal Very arranged at low VOC concentrations Simple and robust technology Arranged for discontinue processes Easy maintenance Easy to place The disadvantages are: Substance can ensure constipations Mixtures of components can ensure a fast disruption Risk of fires in the bed (ketones, terpentines) Zeolite are mainly used in concentration applications. The more concentrated degas must be further treated by means of combustion or condensation. These concentrators have been applied in degasses of needle cabins, process emissions from enamel producers. Click here for more information about air treatment For more books and reading information see our website: Air treatment books overview

Gas purification techniques

Regenerative adsorption zeolite