Separations account for a significant proportion of worldwide energy consumption. Energy-intensive distillation dominates but more energy efficient alternatives such as membrane technology and adsorption by porous materials are in widespread use. For gas separation, pressure swing adsorption (PSA) and temperature swing adsorption (TSA) are two common processes. In PSA, adsorbents are regenerated by reducing pressure, while in TSA they are regenerated by heating.
Adsorbent performance as a function of temperature, pressure and gas composition is a crucial aspect of this technology. Important information for assessing materials for practical applications and for process design and optimization include working capacity, isotherm shape, selectivity, heats of adsorption, and adsorption and desorption kinetics. Such data can be obtained using laboratory gas adsorption measurement techniques, without the need, for example, to use pilot plants. The most common approaches are the volumetric and gravimetric methods.
This article therefore introduces and discusses the characterization of adsorbents for gas separation applications. It covers the performance parameters and data required for such applications, and the laboratory techniques used to obtain this information. Methods for determining multicomponent adsorption are also discussed and future challenges in the field identified.