(EP512170-A1)      Pressure swing adsorption process for sepn. of ethane from a feedstream comprising mixts. of ethane and methane comprises: (a) passing the feedstream at an upper absorption pressure through an adsorption zone contg. a zeolitic molecular sieve of faujasite type having a frame work SiO2/Al2O3 molar ratio of 2-100 and contg. at least 20 equiv.% of Zn cations an contg. not more than 80 equiv. % alkali(ne earth) metal cation(s), where ethane and methane are adsorbed and an effluent stream enriched in methane relative to the feedstream is recovered; (b) regenerating the adsorption zone by depressurinsing the zone to a desorption pressure lower than the adsorption pressure, and recovering a desorption effluent stream comprising ethane and methane; and (c) repressurising the adsorption zone to the adsorption pressure.    USE/ADVANTAGE -   The process gives a high purity methane prod. at higher recoveries than known methods. The zeolitic molecular sieve effectively controls the thermal problems associated with methane coadsorption yet provides suitable sepn. of impurity adsorbates.    (EP512170-B1)      A pressure swing adsorption process for the separation of ethane from a feed stream comprising ethane and methane, said process comprising the steps of: (a) passing the feed stream into an adsorption zone maintained at adsorption conditions including an upper adsorption pressure and containing a zeolitic molecular sieve adsorbent of the faujasite type having a framework SiO2/Al2O3 molar ratio of from 2:1 to 100:1 and containing at least 20 equivalent % of a cation selected from zinc, rare earth metal, hydrogen, ammonium, calcium or mixtures thereof, and containing not more than 80 equivalent % of an alkali or alkaline earth metal cation other than calcium or mixtures thereof, wherein ethane is adsorbed and recovering an adsorption effluent stream enriched in methane relative to the feed stream; (b) regenerating the adsorption zone periodically by depressurising the adsorption zone to a lower desorption pressure and recovering a desorption effluent stream comprising ethane; and thereafter, (c) repressurising the adsorption zone to the upper adsorption pressure; and returning to step (a).