Adsorptive separation of gas streams
A method and system for adsorptive separation of a feed gas mixture provides for increased system efficiency and product recovery. The requirement for purge gas streams consuming desired product gas to regenerate adsorption beds is reduced through an inventive method for adsorbent selection and adsorption bed and process design.
1. A method for substantially separating a carbon monoxide from a feed gas stream comprising carbon monoxide, carbon dioxide, and hydrogen, the method comprising:
passing the feed gas stream through a first adsorption zone in contact with a first adsorbent material selective for carbon monoxide relative to carbon dioxide, and subsequently through a second adsorption zone in contact with a second adsorbent material selective for carbon dioxide relative to hydrogen;
withdrawing from the second adsorption zone a product gas stream enriched in hydrogen; and
regenerating the first adsorption zone by passing an exhaust gas stream from the second adsorption zone through the first adsorption zone, such that at least a portion of the carbon monoxide adsorbed on the first adsorbent material is purged from the first adsorption zone by carbon dioxide.
2. The method according to claim 1 wherein the first adsorbent material is a metal, metal halide, or oxide enhanced adsorbent material.
3. The method according to claim 1 wherein the second adsorbent material is activated carbon.
4. The method according to claim 1 wherein the feed gas stream additionally comprises nitrogen, and the feed gas stream is passed through a third adsorption zone in contact with a third nitrogen adsorbent material.
5. The method according to claim 1 wherein the feed gas stream is a reformate stream from a steam catalytic reformer.
6. The method according to claim 1 wherein the feed gas stream is a reformate stream from a catalytic partial oxidation reformer.
7. The method according to claim 1 wherein regenerating the first adsorption zone additionally comprises passing a product purge gas stream comprising hydrogen through the first adsorbent zone such that at least a portion of the carbon monoxide adsorbed on the first adsorbent material is purged from the first adsorbent zone by the product purge gas stream.
8. The method according to claim 7 wherein the product purge gas stream is additionally passed through the second adsorbent zone such that at least a portion of the carbon dioxide adsorbed on the second adsorbent material is purged from the second adsorbent zone by the product purge gas stream.
9. The method according to claim 2 wherein the second adsorbent material is activated carbon.
10. An adsorptive separation system for substantially separating a carbon monoxide from a feed gas stream comprising carbon monoxide, carbon dioxide, and hydrogen, the system comprising:
an adsorption bed comprising a first adsorption zone containing a first adsorbent material selective for carbon monoxide relative to carbon dioxide, and a second adsorption zone containing a second adsorbent material selective for the carbon dioxide relative to hydrogen;
a feed gas inlet configured to admit the feed gas stream into the adsorption bed such that the feed gas stream can pass through the first adsorption zone in contact with the first adsorbent material, and subsequently through the second adsorption zone in contact with the second adsorbent material;
a product gas outlet configured to withdraw a product gas stream enriched in hydrogen relative to the feed gas stream from the adsorption bed; and
an exhaust gas outlet configured to withdraw an exhaust gas stream from the adsorption bed during regeneration of the adsorption bed, said exhaust gas stream comprising at least a portion of the adsorbed carbon monoxide from the first adsorption zone which has been purged from the first adsorbent material by carbon dioxide.
11. The system according to claim 10 wherein the first adsorbent material is a metal, metal halide, or oxide enhanced adsorbent material.
12. The system according to claim 10 wherein the second adsorbent material is activated carbon.
13. The system according to claim 11 wherein the second adsorbent material is activated carbon.
14. The system according to claim 10 wherein the adsorption bed further comprises a third adsorption zone containing a nitrogen adsorbent material.
15. The system according to claim 13 wherein the adsorption bed further comprises a third adsorption zone containing a nitrogen adsorbent material.
16. The system according to claim 10 wherein the adsorption bed is coupled to a steam catalytic reformer to receive a reformate stream as the feed gas stream.
17. The system according to claim 10 wherein the adsorption bed is coupled to a catalytic partial oxidation reformer to receive a reformate stream as the feed gas stream.