TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The combined adsorbent comprises a blend, a composite or a mixture of both of zeolite and alumna. The adsorbent contains 40-95 wt.% alumna and 5-60 wt.% zeolite. Preferred Process: The gas stream is air, preferably containing water vapor, which is preferably removed as it passes through the adsorbent or by passing through a desiccant comprising activated alumna, silica gel, zeolite 3a or a mixture thereof upstream of the adsorbent. The air contains one or more hydrocarbons which are removed by the adsorbent. SPECIFIC COMPOUNDS - Type X, A or Y zeolite or a mixture of these is preferred, particularly type 4A, 5A or 13X.    EXAMPLE - Water saturated air containing 5 ppm propane and 350-400 ppm carbon dioxide was purified by pressure swing adsorption in an identical pair of vessels, 5.24 inches in diameter and 62 inches high packed with a 56 inch LaRoche A-201 activated alumna bottom layer and a 6 inch zeolite 5A top layer. During adsorption, feed gas was passed upwards through the vessels at 40 degrees C, 65 psig and 15 SCFM. During adsorbent regeneration, carbon dioxide free nitrogen was passed downwards through the vessels at 9.9 SCFM. The PSA process was conducted with the vessels 180degrees out of phase, with 16 minutes of adsorption/production, 0.5 minutes countercurrent depressurization, 12.5 minutes purge and 3 minutes countercurrent repressurization by product backfill in each 32 minute adsorption half-cycle. The product contained less than 3 ppb carbon dioxide and less than 0.5 ppm propane but after several days carbon dioxide and propane concentrations both rose to over 0.1 ppm. The experiment was repeated except the vessels were packed with a 50 inch LaRoche A-201 activated alumna bottom layer and a 12 inch top layer of a blend of 50 vol.% 5A zeolite and 50 vol.% of the alumna. The carbon dioxide and propane concentrations remained constant at 3 ppb and 0.05 ppm respectively over several days of experiment.