Zeolite body (I) is obtd. by further (i) hydrating and (ii) heating a zeolite body previously obtd. by conventional moulding and calcining. Air is contacted with (I) in a pressure swing adsorption-desorption process to adsorb N2 and effect sepn. of O2. Pref. hydration is to a ater content of 5-20 wt.% and heating is at 300 500 deg.C for 0.5 hrs at least. Zeolite is pref. a 5A type but can also be faujasite or mardenite types etc.
