BULK SEPARATION OF CARBON DIOXIDE FROM NATURAL GAS

• US 3,751,878 A
• Filed: 10/20/1972
• Issued: 08/14/1973
• Est. Priority Date: 10/20/1972
• Status: Expired due to Term

• Current Assignee: UOP Des Plaines IL A NY General Partnership
• Original Assignee: John Joseph Collins
• Inventors: Collins, John Joseph
• Primary Examiner(s): Hart, Charles N.
• Application Number:
  US05/299,461
• Time in Patent Office: 298 Days
• Field of Search: 58/58,62,68,75,179,389
• US Class Current: 95/105
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2253/308 Pore size
• CPC Class Codes: B01D 2256/22 Carbon dioxide
• CPC Class Codes: B01D 2256/245 Methane
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2259/40062 Four
• CPC Class Codes: B01D 2259/403 using three beds
• CPC Class Codes: B01D 53/047 Pressure swing adsorption
• CPC Class Codes: C07C 7/13 by molecular-sieve technique
• CPC Class Codes: C07C 9/04 Methane production by treatment of sewage C02F11/04; natural gas, synthetic natural gas C10L3/06
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

In the bulk separation of carbon dioxide from feedstocks containing same in admixture with relatively non-sorbable gases using a zeolitic molecular sieve to adsorb selectively the carbon dioxide, higher product purity is attained by terminating the adsorption stroke using the feedstock while the bed still has capacity to adsorb more carbon dioxide at the same conditions, then purging the void space hydrocarbons from the bed using product carbon dioxide at a high partial pressure, and finally desorbing the bed by pressure reduction.

Claims

2. 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.

3. Process according to claim 2 wherein the feedstock is passed into the 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 all of the carbon dioxide in the void space of said adsorption bed.