7 - Selected adsorption processes

Abstract

This chapter illustrates features of adsorption processes by using numerous examples that vary in their mode of design and operation. Purification of gases includes the drying of air and other industrial gases, the sweetening or removal of acidic gases of natural gas, air purification, and removal of solvents from air streams. Another adsorption process is the separation of a component gas or gases from a mixture of gases. The production of oxygen and nitrogen from air, the separation of n-paraffins from iso-paraffins, and the recovery of hydrogen from industrial gas mixtures are common separation processes. Activated carbon and zeolites are two of the most common adsorbents used for gas separation. The adsorbent properties that enable the separation of gases are the nature of the adsorbate, adsorbent equilibrium, and the rates at which gaseous components diffuse into the pore structure of the adsorbent. The sieving property of zeolites is prominent in the separation of n-paraffins from iso-paraffins and the drying of gaseous streams. The production of nitrogen from air using a molecular sieve carbon depends on the difference in rates of diffusion of nitrogen and oxygen within the adsorbent pore structure.