Zeolite Molecular Sieve Under What Conditions Can Be Used as Adsorbent

Under normal circumstances, the adsorption dryer uses activated alumina as an adsorbent, but activated alumina also has drawbacks. At this time, we need to use zeolite molecular sieve as adsorbent. Zeolite molecular sieve is an excellent adsorbent, it has a larger surface area than alumina, and its surface area pore size is very uniform, with good adsorption selectivity. Even in the case where the partial pressure of water vapor is very low, it still has a large adsorption capacity (activated alumina and silica gel have a greater adsorption capacity only at high partial pressure). Molecular sieves are therefore used for deep dehydration of compressed air.

    However, zeolite zeolite is not the most preferred adsorbent for any application. It also has its own disadvantages. First, the zeolite molecular sieve has a better adsorption capacity than silica and alumina for gases with higher water content. Secondly, zeolites have higher desorption temperatures, greater energy consumption for regeneration, and easier residual moisture. Third, the mechanical strength of zeolite molecular sieves is not high, and they are easily crushed and pulverized under pressure. The long-term use of bulk density can increase by 20%. Increase the adsorption bed resistance. Fourth, zeolite molecular sieves have poor resistance to liquid dripping, and liquid droplets are susceptible to chalking and deterioration. Therefore, in the treatment of compressed air with a large moisture content, the compressed air should be pre-dried with adsorbents such as silica gel and alumina, and the remaining water is then treated with a zeolite molecular sieve. This not only ensures the requirement of deep drying, but also avoids the disadvantages of low adsorption capacity, easy failure, frequent regeneration and replacement of molecular sieves when the water content is high.