|
|
Molecular Sieve Details
Reactivation method:
Insufflate the sieve bed with vapor to exchange the organics out to avoid char formation at first, then reactivate the molecular sieve with common method .For further detail, please abide our latest instruction.
Typical applications:
- Dehydration of many kinds of liquids (say ethanol).
- Dehydration of air.
- Dehydration of refrigerant.
- Dehydration of natural gas or methane.
- Dehydration of cracked gas, ethylene, propylene or butadiene.
Packing:
25 kg paper beg ; 150 kg steel drum.
Attention:
To avoid damp and pre-adsorption of organic before running, or must to be reactivated .Carefully sift the agent over the flowers and into open-form flowers until they are covered with at least a ¼ -inch layer. Add the drying agent slowly; otherwise the flowers may drop their petals or become misshapen if the material is added too fast and there’s no support beneath. Don’t cover the container unless you are using clay desiccant or silica sand.
Place the container in a dark, cool, dry location. If you are using silica gel, refer to the chart below for the length of drying time. For clay desiccant, it may take from 5 to 14 days depending on the type of drying agent, the type of flower used, the thickness of the petals, and the temperature and humidity levels. Thin-petaled flowers usually take about a week, while thicker-petaled flowers take anywhere from 10 days to 2 weeks. The best way to determine if they are dry is to carefully brush aside the agent and check the flowers. When thoroughly dry, gently remove the flowers and carefully use a fine- haired brush to remove any of the particles of desiccant that remain after drying.
|
Zettapac - Structure and Properties
Zettapac molecular sieves are crystalline, highly porous materials, which belong to the class of alumino silicate. These crystals are characterised by a three-dimensional pore system, with pores of precisely defined diameter. The corresponding crystallographic structure is formed by tetrahedras of (AlO4) and (SiO4). These tetrahedras are the basic building blocks for various Zettapac molecular sieve structures, such as Zettapac molecular sieve A and X, the most common commercial adsorbents.
|
|
Molecular Sieve Type A |
Molecular Sieve Type X |
Due to the presence of alumina, Zettapac molecular sieve exhibit a negatively charged framework, which is counter-balanced by positive cations resulting in a strong electrostatic field on the internal surface. These cations can be exchanged to fine-tune the pore size or the adsorption characteristics. For instance, the sodium form of zeolite A has a pore opening of approximately 4 Ångstrom (4 x 10–10 m), called 4A molecular sieve. If the sodium ion is exchanged with the larger potassium ion, the pore opening is reduced to approximately 3 Ångstrom (3A molecular sieve). On ion exchange with calcium, one calcium ion replaces two sodium ions. Thus, the pore opening increases to approximately 5 Ångstrom (5A molecular sieve). Ion exchange with other cations is sometimes used for particular separation purposes.
 |
 |
| Molecular sieve 4Å |
Molecular sieve 3Å |
The pore opening of the sodium form of Zettapac molecular sieve X (13X) is approximately 8 Ångstrom.
The ability to adjust the pores to precisely determined uniform openings allows for molecules smaller than its pore diameter to be adsorbed whilst excluding larger molecules, hence the name “molecular sieve”. The different pore sizes of synthetic Zettapac molecular sieve open up a wide range of possibilities in terms of "sieving" molecules of different size or shape from gases and liquids.
|
Selective Adsorption of Water and other Polar Substances
The up-take of water or other species in zettapac molecular sieve is called adsorption and functions on the basis of physisorption. The main driving force for adsorption is the highly polar surface within the pores. This unique characteristic distinguishes Zettapac molecular sieve from other commercially available adsorbents, enabling an extremely high adsorption capacity for water and other polar components even at very low concentrations.
In addition, the pore size plays a significant role, allowing or prohibiting the entrance of molecules to the pore system.
The adsorption on molecular sieves is therefore dependent on the following physical molecular properties:
- Size and Shape: Molecules larger than the pore opening of the molecular sieve can not be adsorbed, smaller molecules can.
- Molecular Polarity: Molecules with large polarity or polarisability can be adsorbed preferentially under identical conditions.
|
|
|
|
