f200 activated alumina is a white beaded desiccant that adsorbs water molecules in gases, vapors and liquids. It also adsorbs degradation acids (such as those formed in transformer and lubricating oils) and fluoride.
The uniform spherical shape of f200 prevents adsorbent segregation during pneumatic loading, which minimizes channeling and allows higher tower heights for more efficient use. It also offers high crush strength, resistance to amine attack and low abrasion.
Product Description
Grade F-200 is a smooth, spherical activated alumina desiccant made using BASF’s unique manufacturing process. This material is an excellent choice for drying a wide variety of liquids and gases. In gas dehydration applications it can be used to achieve dew points down to -40degF in a fixed-bed configuration. In liquids, it is effective for the drying of kerosene and aromatic compounds and essences.
Activated alumina has a large specific surface area and is chemically inert, providing a good environment for adsorption of many contaminants. Moreover, the pore structure is characterized by a high number of hydroxyl groups, allowing it to adsorb hydrogen-containing molecules (see Figure 8.3). Activated alumina is particularly useful for phosphate, arsenic and fluoride adsorption, especially in a fixed-bed mode. It can be regenerated with dilute NaOH or sulfuric acid.
While all aluminas adsorb water, the water adsorption capacity of a particular alumina depends on several factors including its manufacturing process and the conditions under which it is used. In general, high quality aluminas are capable of adsorbing 35-40 pounds of water per 100 pounds of regenerated alumina in an equilibrated state with air at 90% relative humidity. This is a substantial improvement over silica alumina which can only adsorb about 20 pounds of water per 100 pounds of regenerated silica. This higher adsorption capacity makes aluminas an attractive choice for a wide range of liquid and gas dehydration applications including compressed air and gas drying, transformer and lubricating oil drying and vapor refrigerant dehydration.
Applications
Activated alumina is used as a desiccant to selectively adsorb water in some gases, vapors and liquids. It is also used as a chromatographic analysis carrier, as a catalyst carrier and as a fluoride removal agent in drinking water purification systems. It is regenerated by treating it with lye (sodium hydroxide; NaOH) or sulfuric acid (H2SO4).
Using controlled heating to dehydrate a form of hydrated alumina (Boehmite or alumosilicate) produces an adsorbent with a very large surface area, typically 150-380 m2 per gram. The adsorption capacity increases with temperature because the water molecules escape from the crystal lattice along planes of structural weakness. This resulting material is also resistant to abrasion and amine attack.
In the spherical activated alumina, which is the product used in our fluoride treatment plants, the pore structure and size have been tailored to give high dynamic H2O adsorption capacity. It has a low vapor pressure, which reduces the pressure drop in the gas adsorption tower and contributes to a higher system efficiency. In addition, the sphericity of F-200 helps prevent adsorbent segregation during pneumatic loading and results in less channeling within the adsorption tower thereby minimizing down stream valve and filter plugging problems common with dustier products. It also has a high crush strength which provides resistance to abrasion for longer service life.
Advantages
Activated alumina can be used as an effective desiccant to selectively adsorb water from some gases, vapors and liquids. Its chemical inertness, ionic strength and pore structure make it a powerful adsorbent. Activated alumina can also act as a catalyst carrier and chromatographic analysis carrier.
F-200 spherical activated alumina is an excellent choice for drying air in a variety of applications. This product is made from specially engineered spheres that preferentially adsorb highly polar molecules. While all molecules are adsorbed to some degree, stream conditions such as pressure, concentration and molecular weight, temperature and site competing molecules affect the efficiency of adsorption.
The alumina desiccant is made up of microporous spheres that have been heat treated to enhance the adsorption properties. The pores are wide and the surface area is high making it a powerful desiccant for a variety of applications. In addition to its desiccant properties, alumina has exceptional crush strength, making it a good choice for the stresses of industrial applications.
Compared to molecular sieve, which is also capable of adsorbing moisture, activated alumina has a much higher affinity for water. It is this property that makes it an ideal choice for use in air dryers and other industrial applications where the ability to adsorb large quantities of moisture is important. Unlike silica gel, which can crack when exposed to high temperatures, alumina is not sensitive to this type of degradation.
Requirements
Activated alumina is produced by controlled dehydration of aluminum oxide hydroxide (Boehmite) to form a porous material with a specific surface area in the range of 150-380 m2 per gram. The pore structure of the finished adsorbent is resistant to high temperatures and abrasion. This makes it a highly durable, chemically inert substance which can be easily regenerated for continued use.
The process is carried out at a temperature of about 375deg to 450degC where water molecules are released, but complete dehydroxylation is not allowed to occur. The product is then bonded with a special binder to form spheres or granules of the desired size and shape. The final adsorbent has a loss on ignition of 4 to 7% and can be used in vapor phase, liquid or gas applications.
BASF f200 activated alumina desiccants are hard, spherical beads which have a much higher strength than silica gel. This allows them to be used in heatless regenerative dehumidifying equipment. The sphericity of the product prevents adsorbent segregation during pneumatic loading of the tower and offers excellent dynamic H2O adsorption capacity. The uniform spherical size also minimizes channeling and provides for more efficient use of the entire desiccant tower.
F200 activated alumina has good performance in the removal of fluoride and arsenic in drinking water treatment systems. It is able to remove fluoride and arsenic at a pH of about 5.5. It is less sensitive to compressor oil vapours than silica gel and can withstand the high temperature required for this application.