An air and gas purification system having combined adsorbent material layers in a regenerable adsorbent system. A first adsorbent material, molecular sieve material, is positioned at the inlet end of the adsorbent bed and a second material, activated alumina, is positioned at the outlet end. Additional adsorbent materials may be positioned between the inlet adsorbent material and the outlet adsorbent material. This system, utilizing the combination of adsorbent layers, is particularly useful for fuel cell applications, where the adsorbent system is positioned in the incoming oxidant stream to reduce, and preferably remove, the contaminants that would affect the efficiency of the fuel cell. Using such a system allows using ambient air as the oxygen source.