22 Regeneration of granular activated carbon containing benzene with natural gas

摘要

Adsorption, a process where pollutants in gas or liquid streams are removed utilizing a solid surface, is commonly used by industry to economically control a wide variety of both air and water pollution problems.~(1-4) An adsorbing solid (adsorbent) of highly porous small granular particles is used in a vertical packed-bed in most industrial applications. The pores are generally very small resulting in large internal surface areas of the particles. Adsorption usually occurs in-side the pores at specific sites on the abosrbent particle. Separation results due to variations in molecular weight, size, shape or polarity of various pollutants. The key to successful separation is the difference in surface attraction beteen the adsorbing compound (adsorbate) and other components in the fluid stream. In addtion, physical adsorption is desired rather than chemisorption since physical adsorption is reversible and the adsorbent can be reused after reactivation (regeneration). Industrial adsorbents must have very high surface area, good structural strength, and the a bility to reverse the adsorption process allowing removal of the adsorbate (desorption). Granular activated carbon (GAC) is the most frequently used adsorbent in industrial applications due to its surface properties, large surface area, low pressure drop and relatively low cost.