Process for purifying a gas by adsorption of the impurities on several active carbons

• US 6,402,813 B2
• Filed: 01/04/2001
• Issued: 06/11/2002
• Est. Priority Date: 01/25/2000
• Status: Expired due to Fees

• Current Assignee: L'Air Liquide SA
• Original Assignee: L'Air Liquide SA
• Inventors: Moreau, Serge, Monereau, Christian
• Primary Examiner(s): Simmons, David A.
• Assistant Examiner(s): LAWRENCE JR, FRANK M
• Application Number:
  US09/753,660
• Publication Number:
  US 20010009125A1
• Time in Patent Office: 523 Days
• Field of Search: 95/96--03, 951/17, 951/21, 951/39--43, 959/01, 961/32, 961/31, 502/180, 502/416, 502/417, 423/248
• US Class Current: 95/96
• CPC Class Codes: B01D 2253/102 Carbon
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2253/306 Surface area, e.g. BET-specific surface
• CPC Class Codes: B01D 2253/308 Pore size
• CPC Class Codes: B01D 2256/10 Nitrogen
• CPC Class Codes: B01D 2256/12 Oxygen
• CPC Class Codes: B01D 2256/16 Hydrogen
• CPC Class Codes: B01D 2256/18 Noble gases
• CPC Class Codes: B01D 2256/20 Carbon monoxide
• CPC Class Codes: B01D 2256/24 Hydrocarbons
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/306 Organic sulfur compounds, e.g. mercaptans
• CPC Class Codes: B01D 2257/406 Ammonia
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/70 Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
• CPC Class Codes: B01D 2257/7022 Aliphatic hydrocarbons
• CPC Class Codes: B01D 2257/7027 Aromatic hydrocarbons
• CPC Class Codes: B01D 2257/708 Volatile organic compounds V.O.C.'s
• CPC Class Codes: B01D 2257/80 Water
• CPC Class Codes: B01D 2259/40015 : with two sub-steps
• CPC Class Codes: B01D 2259/40062 : Four
• CPC Class Codes: B01D 2259/40083 : Regeneration of adsorbents in processes other than pressure or temperature swing adsorption
• CPC Class Codes: B01D 2259/402 : using two beds
• CPC Class Codes: B01D 2259/4068 : using more than ten beds
• CPC Class Codes: B01D 2259/4146 : Contiguous multilayered adsorbents
• CPC Class Codes: B01D 53/0423 : Beds in columns
• CPC Class Codes: B01D 53/0462 : Temperature swing adsorption
• CPC Class Codes: B01D 53/053 : with storage or buffer vessel
• CPC Class Codes: B01J 20/20 : comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 20/28004 : Sorbent size or size distribution, e.g. particle size
• CPC Class Codes: B01J 20/28011 : Other properties, e.g. density, crush strength
• CPC Class Codes: B01J 20/28016 : Particle form
• CPC Class Codes: B01J 20/28052 : Several layers of identical or different sorbents stacked in a housing, e.g. in a column
• CPC Class Codes: B01J 20/28057 : Surface area, e.g. B.E.T specific surface area
• CPC Class Codes: B01J 20/28069 : Pore volume, e.g. total pore volume, mesopore volume, micropore volume
• CPC Class Codes: B01J 20/28078 : Pore diameter
• CPC Class Codes: B01J 20/2808 : being less than 2 nm, i.e. micropores or nanopores
• CPC Class Codes: B01J 2220/42 : Materials comprising a mixture of inorganic materials materials coated or impregnated on a carrier B01J20/32
• CPC Class Codes: Y02C 20/40 : of CO2
• CPC Class Codes: Y10S 95/901 : Activated carbon

Abstract

The gas stream containing one or more gaseous impurities from the group formed by carbon dioxide, water vapor, H₂S, alcohols, SO₂ and C₁-C₈ saturated or unsaturated, linear, branched or cyclic hydrocarbons is brought into contact with several different porous carbon adsorbents, that is to say active carbons having different properties and characteristics. The gas is air, nitrogen, hydrogen produced by the reforming or cracking of ammonia or the combustion gas or fermentation gas.

Claims

1. A process for the purification of a gas stream containing at least one gaseous impurity selected from the group consisting of CO₂, saturated and unsaturated, linear, branched and cyclic hydrocarbons containing at least one carbon atom in their hydrocarbon structure, mercaptans, H₂S, SO₂, chlorine, ammonia, alcohols, amines and volatile organic compounds, the process comprising:

bringing the gas stream to be purified successively into contact with particles of a first porous carbon adsorbent, and then with particles of a second porous carbon adsorbent, the particles of the first and second porous carbon adsorbents forming separate and successive layers to remove at least one gaseous impurity on the separate and successive layers of porous carbon adsorbents, and

wherein the particles of the first porous carbon adsorbent are defined by a first density (D1) and a first specific surface area (SSA1) and the particles of the second porous carbon adsorbent are defined by a second density (D2) and a second specific surface area (SSA2) such that;

2. The process according to claim 1, wherein the ratio of the volume of particles of the first porous carbon adsorbent to the volume of particles of the second porous carbon adsorbent is between 5/95 and 95/5.

3. The process according to claim 1, wherein the first and second porous carbon adsorbents are selected from among active carbons, produced from at least one element selected from the group consisting of coconut husk, peat, lignite, coal, anthracite, polymers and resins.

4. The process according to claim 1, further comprising bringing the gas stream into contact with at least one zeolitic particulate adsorbent.

5. The process according to claim 4, wherein the zeolite is a X zeolite, an A zeolite or a faujasite, exchanged to at least 70% with lithium or with calcium, and/or a faujasite whose Si/Al ratio is between about 1 and 1.2.

6. The process according to claim 1, further comprising bringing the gas stream into contact with at least one adsorbent formed from particles of activated alumina or of silica gel.

7. The process according to claim 1, wherein the adsorbents are present in a PSA or TSA unit.

8. The process according to claim 1, wherein the gas stream is a hydrogen stream.

9. The process according to claim 1, wherein the gas stream is an air stream or nitrogen stream.

10. The process according to claim 1, wherein the particles of the first porous carbon adsorbent are defined by:

a first pore volume (PV1) of between 0.5 and 1.5 cm³/g;

a first density (D1) of between 350 and 500 kg/m³;

a first specific surface area (SSA1) of between 500 and 1800 m²/g; and

a first mean pore size (MPS1)>

6 angstroms.

11. The process according to claim 1, wherein the particles of the second porous carbon adsorbent are defined by:

a second pore volume (PV2) of between 0.4 and 1.3 cm³/g;

a second density (D2) of between 400 and 650 kg/m³;

a second specific surface area (SSA2) of between 400 and 1500 m²/g; and

a second mean pore size (MPS2)>

4 angstroms.

12. The process according to claim 1, wherein the particles of the first and second porous carbon adsorbents have different mean particle sizes.

13. The process according to claim 1, wherein the gas is natural gas, a combustion gas or a fermentation gas.

14. The process according to claim 1, wherein the particles of the first and second porous carbon adsorbents form separate and successive layers within a single unit.

15. A process for the purification of a gas stream containing water vapor as a gaseous impurity and at least one other gaseous impurity selected from the group consisting of CO₂, saturated and unsaturated, linear, branched and cyclic hydrocarbons containing at least one carbon atom in their hydrocarbon structure, mercaptans, H₂S, SO₂, chlorine, ammonia, alcohols amines and volatile organic compounds, the process comprising:

bringing the gas stream to be purified successively into contact with particles of a first porous carbon adsorbent and then with particles of a second porous carbon adsorbent, the particles of the first and second porous carbon adsorbents forming separate and successive layers for removing at least one gaseous impurity on the separate and successive layers of porous carbon adsorbents, and

wherein the praticles of the first porous carbon adsorbent are defined by a first density (D1)and a first specific surface area (SSA1) and the particles of the second porous carbon adsorbent are defined by a second density (D2) and a second specific surface area (SSA2) such that;