Method for purifying hydrogen based gas mixture using a lithium- exchanged X zeolite

• US 5,912,422 A
• Filed: 01/21/1998
• Issued: 06/15/1999
• Est. Priority Date: 05/24/1996
• Status: Expired due to Term

• Current Assignee: L'Air Liquide Societe Anonyme Pour L'Etude et L'Exploitation Des Procedes Georges Claude (L'Air Liquide SA)
• Original Assignee: L'Air Liquide Societe Anonyme Pour L'Etude et L'Exploitation Des Procedes Georges Claude (L'Air Liquide SA)
• Inventors: Bomard, Olivier, Vigor, Xavier, Moreau, Serge, Jutard, Jerome
• Primary Examiner(s): SPITZER, ROBERT H
• Application Number:
  US08/983,073
• Time in Patent Office: 510 Days
• Field of Search: 95/96-98, 95/100-105, 95/130, 95/139-141, 95/143
• US Class Current: 95/96
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2253/106 Silica or silicates
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2253/1085 characterized by a silicon-aluminium ratio
• CPC Class Codes: B01D 2257/102 Nitrogen
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/7022 Aliphatic hydrocarbons
• CPC Class Codes: B01D 2259/4067 using ten beds
• CPC Class Codes: B01D 2259/4146 Contiguous multilayered adsorbents
• CPC Class Codes: B01D 53/02 by adsorption, e.g. preparative gas chromatography solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01
• CPC Class Codes: B01D 53/04 with stationary adsorbents B01D53/025 takes precedence
• CPC Class Codes: B01D 53/047 Pressure swing adsorption
• CPC Class Codes: C01B 2203/043 Regenerative adsorption process in two or more beds, one for adsorption, the other for regeneration
• CPC Class Codes: C01B 2203/047 the impurity being carbon monoxide
• CPC Class Codes: C01B 2203/0475 the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/048 the impurity being an organic compound
• CPC Class Codes: C01B 3/56 by contacting with solids; Regeneration of used solids C01B3/508 takes precedence
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

Process for the separation of the hydrogen contained in a gas mixture contaminated by carbon monoxide and containing at least one other impurity chosen from the group consisting of carbon dioxide and saturated or unsaturated, linear, branched or cyclic C₁ -C₈ hydrocarbons, comprising bringing the gas mixture to be purified into contact, in an adsorption region, with at least:

one first adsorbent selective at least for carbon dioxide and for C₁ -C. hydrocarbons and

one second adsorbent which is a zeolite of faujasite type exchanged to at least 80% with lithium, the Si/Al ratio of which is less than 1.5, in order to remove at least carbon monoxide (CO).

Claims

1. Process for the separation of hydrogen contained in a gas mixture contaminated by carbon monoxide and containing at least one other impurity selected from the group consisting of carbon dioxide and saturated or unsaturated linear, branched or cyclic C₁ -C₈ hydrocarbons, which comprises bringing the gas mixture to be purified into contact, in an adsorption region, with at least:

one first adsorbent selective at least for carbon dioxide and for C₁ -C₈ hydrocarbons, and

one second adsorbent which is a faujasite zeolite exchanged to at least 80% with lithium, and having a Si/Al ratio which is less than 1.5, in order to remove carbon monoxide.

2. Process according to claim 1, wherein the gas mixture to be purified contains more than 45% of gaseous hydrogen.

3. Process according to claim 1, wherein the gas mixture to be purified contains more than 70% of gaseous hydrogen.

4. Process according to claim 1, wherein the gas mixture additionally comprises nitrogen as an impurity.

5. Process according to claim 4, wherein at least a portion of the nitrogen is adsorbed on at least one third adsorbent placed between the first and second adsorbents.

6. Process according to claim 5, wherein the third adsorbent is a zeolite.

7. Process according to claim 5, wherein the third adsorbent is a 5A zeolite.

8. Process according to claim 1, wherein the gas mixture additionally contains nitrogen.

9. Process according to claim 1, wherein the adsorption region is maintained under a pressure of between 5×

10⁵ and 70×

10⁵ Pa.

10. Process according to claim 1, wherein the adsorption region is maintained under a pressure of between 15×

10⁵ and 30×

10⁵ Pa.

11. Process according to claim 1, wherein the gas mixture to be purified is first brought into contact with the first adsorbent selective for carbon dioxide and for C₁ -C₈ hydrocarbons, and then, in a second step, with the second adsorbent of faujasite zeolite containing lithium.

12. Process according to claim 1, wherein the first adsorbent selective for carbon dioxide and for C₁ -C₈ hydrocarbons is an active charcoal, a prefilter charcoal, a silica gel or a mixture thereof.

13. Process according to claim 1, wherein the faujasite zeolite is exchanged to at least 90% with lithium.

14. Process according to claim 1, wherein the Si/Al ratio of the faujasite zeolite is between 1 and 1.2.

15. Process according to claim 1, wherein the Si/Al ratio of the faujasite zeolite is equal to 1.

16. Process according to claim 1, wherein the ratio by weight of the first adsorbent to the second adsorbent is between 10/90 and 85/15.

17. Process according to claim 1, wherein the ratio by weight of the first adsorbent to the second adsorbent is between 50/50 and 80/20.

18. Process for carrying out a treatment cycle comprising the stages consisting in:

a) passing a hydrogen-based gas mixture contaminated by at least carbon monoxide and containing at least one other impurity selected from the group consisting of carbon dioxide and C₁ -C₈ hydrocarbons into an adsorption region comprising at least;

one first adsorbent bed composed of a first adsorbent selective for at least carbon dioxide and C₁ -C₈ hydrocarbons and,

one second adsorbent bed composed of a second adsorbent which is a faujasite zeolite exchanged to at least 80% with lithium, and having a Si/Al ratio which is less than 1.5, for adsorbing carbon monoxide;

b) desorbing the carbon monoxide and the other impurity or impurities adsorbed on said at least first and second adsorbents by setting up a pressure gradient and progressively lowering the pressure in said adsorption region, so as to recover the carbon monoxide and the other impurity or impurities via an inlet of said adsorption region; and

c) raising the pressure in said adsorption region by introducing a stream of pure hydrogen via an outlet of the adsorption region.

19. Process according to claim 18, wherein in stage a), the adsorption region is maintained under a pressure of between 5×

10⁵ and 70×

10⁵ Pa, and at a temperature of between 0 and 80°

C.

20. Process according to claim 18, wherein in stage a), the adsorption region is maintain under a pressure of 15×

10⁵ and 30×

10⁵ Pa, and at a temperature of between 0 and 80°

C.