TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Process: The feed gas from which the undesired component has been removed is fed to a downstream cryogenic separation process. The adsorbent is regenerated by a regeneration gas. The depressurization is effected by feeding to the zone a gas at higher pressure from upstream of the adsorption zone.Preferred Gas: The feed gas is synthetic gas, natural gas, or air.Preferred Component: The undesired components comprise carbon dioxide and water. The adsorbent comprises silica gel, activated alumina, impregnated alumina, or alumina, and a zeolite.Preferred Zeolite: The zeolite is of X type, A type, LSX type having a silicon to aluminum ratio of 1.0-1.25.Preferred Parameter: The feed gas is at -50-80 (preferably 5-50)degreesC. The regeneration of the adsorbent is carried out at 0-400degreesC. The molar ratio of regeneration gas to feed gas is 0.05-0.8. The regeneration gas is at a pressure of 10000-2000000 N/m2. The feed gas is at a pressure of at least100000 (preferably 200000-4000000) N/m2. The adsorption cycle for all the adsorption zones is the same duration. The ratio of the duration of the adsorption step to the adsorption cycle is not less than the ratio of one less than the number of adsorption zones to the number of adsorption zones. The process has three adsorption zones. The number of zones in the adsorption step at any point during the cycle is one fewer than the total number of adsorption zones.Preferred Device: The adsorption zone is defined by horizontal, vertical, or radial bed vessel. The flow controller comprises conduits for gas flow, valve, and valve controller. EXAMPLE - A run was simulated at 300000 N/m2 using a large adsorbent bead of 2.4-5 mm diameter. Zeolite 13X of density 640 kg/m3, was used as the adsorbent. The molar purge to air ratio was 0.15, contact time was set at 7 seconds and the temperature of the feed gas at 15degreesC. The beds (3 beds) were taken to be 5 m in diameter. The approach of fluidization of the bed was constant for runs at a given pressure and was less than 70%. A maximum regeneration temperature of 140degreesC was used. Results showed an airflow of 140000 Nm3/hour, and pressure drop (air and hot purge) of 2808 and 1518 Pa/m, respectively.