Abstract: The present invention provides for a thermal swing adsorption process for the removal of trace impurities such as oxides of nitrogen and hydrocarbons from air prior to its separation by cryogenic distillation. The process may utilize three adsorbent layers, the first primarily removes water; the second primarily removes carbon dioxide; and the third layer is a composite adsorbent layer which removes the oxides of nitrogen and hydrocarbons from the air stream. Another embodiment employs a two layer adsorbent system to remove the impurities. Additionally, a single layer of composite adsorbent may be used to remove water, carbon dioxide, oxides of nitrogen, and hydrocarbons from the air stream.

Abstract: The present invention provides for a process for purifying atmospheric air prior to its separation by cryogenic distillation. The process utilizes three adsorbent layers, the first primarily removes water; the second primarily removes CO2; and the third layer is designed to remove displaced gas components such as N2O and hydrocarbons which are displaced by the second layer. It has been found that CaX type adsorbents provide the removal of N2O and hydrocarbons in the third layer.