Monocots radial adsorbers in series

A process for purifying a feed gas stream comprising a main component, water (HO) and carbon dioxide (CO), as well as said incidental impurities, wherein: a) the flow is introduced feed gas into at least one radial adsorber 2 grids containing as the sole adsorption bed a bed of activated alumina or silica gel, which adsorbs preferentially O H, b) introducing the gas from step a) in at least one radial adsorber 2 grids containing as the sole adsorption bed, a molecular sieve bed, which is preferentially adsorbs CO and incidental impurities, and c) recovering a gas from the step b) enriched in lead compound and capable of undergoing cryogenic distillation.