TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The hydrocarbons contained in the natural gas feed stream comprise 3C+ hydrocarbons. The hydrocarbons co-adsorbed on the adsorbent comprise 4C+ hydrocarbons. They further include 3C hydrocarbons. The natural gas feed stream contains less or greater than 4 mole% nitrogen, 4-15 mole% 3C+ hydrocarbons, or greater or less than 2 mole% carbon dioxide. The first product stream contains over 90 mole% methane. The co-adsorbed hydrocarbons comprise 3C+ hydrocarbons.    TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: The methane-containing stream for purging the hydrocarbon-selective adsorbent is provided by co-currently depressurizing the first pressure swing adsorption unit to form a methane-containing stream having a pressure lower than the first product stream and a pressure higher than the waste stream. The product stream is at a pressure of 100-800 psia. The waste stream is at a pressure of less than 10 psia. The methane-containing stream is at a pressure of 20-100 psia. The process further comprises subsequent to forming the combined stream of methane and co-adsorbed hydrocarbons, separating the co-adsorbed hydrocarbons from the combined stream. The 3C+ hydrocarbons are separated from the combined stream by condensing the 3C+ hydrocarbons. Preferred Component: The adsorbent in the first pressure swing absorption unit is a crystalline titanium silicate molecular sieve, preferably CTS-1 (sic) or barium-ETS-4 (sic). It is selective for carbon dioxide. The hydrocarbon-selective absorbent is an amorphous carbon or silica gel adsorbent. The adsorbent selective for carbon dioxide is a silica gel, or an activated carbon. The first adsorbent in the first pressure swing adsorbent unit contains a mixture of CTS-1 and equilibrium adsorbent having a greater affinity for 3C+ hydrocarbon over methane. The equilibrium adsorbent is silica gel, ZnX, activated carbon or alumina. The crystalline titanium silicate is CTS-1 or an alkaline earth-exchanged ETS-4. The pressure swing adsorption unit further contains a silica gel carbon dioxide-selective adsorbent; or an activated carbon, or carbon molecular sieve carbon dioxide-selective adsorbent.