The separation and purification of fluid mixtures (gas or liquid) by adsorption is a major unit operation in the chemical, petrochemical, environmental, pharmaceutical, and electronic gas industries. A list of the key commercial applications of this technology is given in Table 1.1 The phenomenal growth in the development of this technology is demonstrated by Fig. 1, which shows a year-by-year tally of U.S. patents issued between 1980 and 2000 on five different topics of adsorption.1 The total number of patents is overwhelming. Fig. 1 U.S. patent survey of adsorption topics.

Table 1 Key commercial applications of adsorption technology

Gas separation
Gas drying
Trace impurity removal
Air separation
Carbon dioxide-methane separation
Solvent vapor recovery
Hydrogen and carbon dioxide recovery from steam-methane reformer off-gas
Hydrogen recovery from refinery off-gas
Carbon monoxide-hydrogen separation
Alcohol dehydration
Production of ammonia synthesis gas
Normal-isoparaffin separation
Ozone enrichment
Liquid separation
Liquid drying
Trace impurity removal
Xylene, cresol, cymene isomer separation
Fructose-glucose separation
Fatty chemicals separation
Breaking azeotropes
Carbohydrate separation
Environmental separation
Municipal and industrial waste treatment
Ground and surface water treatment
Air pollution control
VOC removal
Mercury vapor removal
Bioseparation and pharmaceutical separation
Recovery of antibiotics
Purification and recovery of enzymes
Purification of proteins
Recovery of vitamins
Separation of enantiomers of racemic compounds
Removal of micro-organisms
Home medical oxygen production
Electronic gas purification
Production of ultrahigh-purity N2, Ar. He, H2, O2
Purification of fluorinated gases NF3, CF4, C2F6, SiF4
Purification of hydrides NH3, PH3, ASH3, SIH4, Si2H6