Patent ID: 7828877

Claim:
An adsorptive gas separation process for producing a purified methane product gas from a feed gas mixture comprising at least methane and carbon dioxide, wherein the feed gas mixture comprises at least about 10% carbon dioxide, and the purified methane product gas is produced by adsorption of the feed gas mixture in an adsorber in contact with at least a first adsorbent material suited for adsorbing at least a majority of the carbon dioxide in the feed gas stream, and subsequently a second adsorbent material suited for substantially removing remaining amounts of carbon dioxide while substantially excluding methane from adsorption, and wherein the purified methane product gas contains less than about 5000 ppm carbon dioxide, wherein the first adsorbent material is selected from the group consisting of aluminas, silicas, silica gel, hydrophohic zeolites, activated carbon and combinations thereof and the second adsorbent material is selected from the group consisting of zeolite 3A, carbon molecular sieves, titanosilicate molecular sieve materials and combinations thereof, and the separation process further includes vacuum assisted desorption of the adsorber during regeneration of the adsorber.