Bulk separation of carbon dioxide from natural gas

Claim 1

Process for bulk separation of carbon dioxide from admixture with methane which comprises passing at a temperature of from 150* F to 900* F and at a pressure of from 100 to 2,000 psia, a gaseous feedstock comprising a mixture of carbon dioxide and methane containing from 10 to 75 mole per cent carbon dioxide into an adsorption bed containing a zeolitic molecular sieve adsorbent having a pore diameter large enough to adsorb CO2 to selectively adsorb CO2 and recover methane as an effluent stream, said feedstock being passed into said adsorption bed for a time not greater than that which results in exceeding the further capacity of the bed at the same conditions to adsorb at least some of the carbon dioxide in the void space of said bed, terminating the flow of the said feedstock into the bed, and cocurrently passing a stream consisting essentially of carbon dioxide thereinto, said stream having a carbon dioxide partial pressure at least 0.8 as great as the partial pressure of carbon dioxide in the said feedstock, in an amount sufficient to purge substantially all of the methane from the void space of the bed, and thereafter withdrawing at least a portion of the carbon dioxide from said bed by adiabatically reducing the pressure thereon.