TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The process also involves contacting the first purified gas stream with a carbon dioxide adsorbent comprising alumina, impregnated alumina, A zeolites, or X zeolite, to form a second purified gas stream; regenerating the carbon dioxide adsorbent; contacting the second purified gas stream with a nitrous oxide or hydrocarbon adsorbent comprising calcium X, sodium X, or barium X zeolites to form a third purified gas stream; regenerating the nitrous oxide or hydrocarbon adsorbent. The method also involves passing a regeneration gas over the composite adsorbent during regeneration.Preferred Condition: The feed gas stream is at 0-50 degrees C and 2-20 atm. The composite adsorbent is generated at an absolute pressure of 0.1-20 atm.Preferred Composition: The adsorbent contains 0.1-10 wt.% metal oxide.Preferred Component: The metal oxide comprises iron, zinc, vanadium, or titanium, preferably alumina. The nitrous oxide or hydrocarbon adsorbent is the same material as the carbon dioxide adsorbent. The regeneration gas comprises oxygen, nitrogen, hydrogen, and/or argon.Preferred Property: The composite adsorbent has a specific surface area of 625-675 m2/g, and an average pore diameter of at most 3 nm. EXAMPLE - Pressure swing adsorption (PSA) experiment was carried out to compare performance of base-treated alumina (sample A) describe in US5656064 with layered bed of alumina/silica gel composite (20 vol.%) followed by base-alumina (80 vol.%) (sample B). The PSA was conducted with water-saturated air at 25 degrees C, a feed flow rate of 30 lbmol/hour/ft2, feed pressure of 30 psig, and a molar purge/air ratio of 0.55. Purge was carried out with nitrogen at 8 psig, 25 degrees C. The results showed that relative volume for water removal for sample A was 1 and for sample B was 0.43; relative bed volume for carbon dioxide removal of for sample A was 1 and for sample B was 0.62; and % water removed in composite alumina/silica layer for sample B was 99%.