Patent ID: 7713333

Claim:
A pressure swing adsorption process for purifying a gas stream containing at least water and carbon dioxide as impurities, the process comprising: passing the gas stream over at least one bed containing at least two zones of adsorbents in an adsorption step, the first zone positioned proximate to a feed end of the at least one bed, the first zone comprising at least one layer having at least one first adsorbent and the second zone positioned such that the gas stream passes over the second zone after passing over the first zone, the second zone comprising at least second and third adsorbents combined as a mixture or a composite, the at least one first adsorbent selected from the group comprising: activated alumina, silica gel or mixtures thereof; the second adsorbent selected from the group comprising: activated alumina, silica gel or mixtures thereof; and the third adsorbent comprising a zeolite or mixture of zeolites; wherein the volume of the first zone comprises not more than 50% by volume of the total volume of the first and second zones.