Molecular sieves, 4 Å - beads,8-12 mesh, high purity , CAS No.M103749

Item Number

M103749

• Synonyms: 4A
• Specifications & Purity: beads,8-12 mesh
• Storage Temp: Desiccated
• Shipped In: Normal

Product Description

Choosing a Molecular Sieve: 1. The preferential adsorption of one molecule over another depends upon pore diameter and mesh size. 2. The dynamic capacity of the silica gel for adsorbing a particular compound is governed by the internal surface area; the greater the surface area, the greater the dynamic capacity. 3. Rate of adsorption and sharpness of resolution are dependent chiefly on particle size and column packing; a fine particle size gives optimum sharpness of resolution. 4. Liquids are most readily adsorbed from solvents in which they are least soluble; a good solvent makes a good desorbing agent. 5. Highly polar liquids are readily adsorbed. Compounds having hydroxyl groups, or containing oxygen are strongly adsorbed. 6. For similar compounds, the higher the molecular weight the higher the selectivity. 7. For hydrocarbons of similar molecular weight, adsorptivity increases with the number of double bonds. Molecular sieves are crystalline metal aluminosilicates having a three-dimensional interconnecting network of silica and alumina tetrahedra. Natural water of hydration is removed from this network by heating to produce uniform cavities which selectively adsorb molecules of a specific size. This 4A form with sodium ions has the effective pore opening of 4?, thus excluding molecules of effective diameter >4? (for example: propane). The 8 to 12-mesh type is common in liquid-phase applications. Molecular sieves are considered a universal drying agent in polar and nonpolar media.