Method of decarbonating a combustion fume with extraction of the solvent contained in the purified fume

• US 20060188423A1
• Filed: 01/23/2006
• Published: 08/24/2006
• Est. Priority Date: 01/28/2005
• Status: Active Grant

• Current Assignee: Evonik Degussa GmbH
• Original Assignee: Institut Francais Du Petrole
• Inventors: Magna, Lionel, Cadours, Renaud, Barrere-Tricca, Cecile, Lecomte, Fabrice
• Granted Patent: US 7,459,134 B2
• Time in Patent Office: Days
• US Class Current: 423/220
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents

Abstract

The combustion fume flowing in through line 1 is decarbonated by contacting with a solvent in column C2. The solvent laden with carbon dioxide is regenerated in zone R. The purified fume discharged through line 9 comprises part of the solvent. The method allows to extract the solvent contained in the purified fume. The purified fume is contacted in zone ZA with a non-aqueous ionic liquid of general formula Q⁺ A⁻; Q⁺ designates an ammonium, phosphonium and/or sulfonium cation, and A⁻ an anion likely to form a liquid salt. The solvent-depleted purified fume is discharged through line 17. The solvent-laden ionic liquid is regenerated by heating in evaporation device DE. The solvent separated from the ionic liquid in device DE is recycled.

Claims

1. ) A method of treating a combustion fume comprising nitrogen and at least one of the acid compounds as follows:

carbon oxides, nitrogen oxides and sulfur oxides, wherein the following stages are carried out;

a) contacting the fume with a solvent capturing the acid compounds so as to obtain, on the one hand, a solvent-comprising purified fume and, on the other hand, a solvent laden with acid compounds, and

b) contacting the purified fume obtained in stage a) with a non-aqueous ionic liquid so as to obtain a solvent-depleted purified fume and a solvent-laden ionic liquid, the ionic liquid having as general formula Q⁺ A⁻

;

Q⁺ designating an ammonium, phosphonium and/or sulfonium cation, and A⁻

an anion likely to form a liquid salt.

2. ) A method as claimed in claim 1, wherein the following stage is also carried out:

c) regenerating the solvent-laden ionic liquid so as to recover, on the one hand, a solvent-depleted ionic liquid and, on the other hand, a solvent-comprising effluent.

3. ) A method as claimed in claim 2 wherein, in stage c), the solvent-laden ionic liquid is heated to evaporate the solvent-comprising effluent.

4. ) A method as claimed in claim 2 wherein, prior to stage a), the fume is contacted with the effluent obtained in stage c).

5. ) A method as claimed in claim 1, wherein the solvent laden with acid compounds obtained in stage a) is regenerated by expansion and/or by heating.

6. ) A method as claimed in claim 1, wherein prior to stage b), the purified fume obtained in stage a) is cooled in order to condense part of the solvent.

7. ) A method as claimed in claim 1, wherein the solvent comprises at least one compound selected from among glycols, ethers, glycol ethers, alcohols, sulfolane, N-methylpyrrolidone, propylene carbonate, ionic liquids, amines, alkanolamines, amino-acids, amides, ureas, phosphates, carbonates and alkali metal borates, water.

8. ) A method as claimed in claim 7, wherein the solvent contains water.

9. ) A method as claimed in claim 1, wherein anion A⁻

is selected from the groups comprising the following ions;

halogenides, nitrate, sulfate, phosphate, acetate, halogenoacetates, tetrafluoroborate, tetrachloroborate, hexafluoro-phosphate, hexafluoroantimonate, fluorosulfonate, alkylsulfonates, perfluoro-alkylsulfonates, bis(perfluoroalkylsulfonyl)amidides, tris-trifluoromethanesulfonyl methylide of formula C(CF₃SO₂)₃⁻

, alkylsulfates, arenesulfates, arenesulfonates, tetraphenylborate and tetraphenylborates whose aromatic rings are substituted.

10. ) A method as claimed in claim 1, wherein cation Q⁺ has one of the following general formulas:

[NR¹R²R³R⁴]⁺, [PR¹R²R³R⁴]⁺, [R¹R²N═

CR³R⁴]⁺ and [R¹R²P═

CR³R⁴]⁺ where R¹, R², R³ and R⁴represent hydrogen or a hydrocarbyl having 1 to 30 carbon atoms, except for cation NH₄⁺ for [NR¹R²R³R⁴]⁺.

11. ) A method as claimed in claim 1, wherein cation Q⁺ is derived from a nitrogen and/or phosphorus heterocycle comprising 1, 2 or 3 nitrogen and/or phosphorus atoms, the heterocycle consisting of 4 to 10 carbon atoms.

12. ) A method as claimed in claim 1, wherein cation Q⁺ has one of the general formulas as follows:

R¹R²N⁺═

CR³-R⁵-R³C═

N⁺R¹R² and R¹R²P⁺═

CR³-R⁵-R³C═

P⁺R¹R², where R¹, R² et R³ represent hydrogen or a hydrocarbyl remainder having 1 to 30 carbon atoms and where R⁵ represents an alkylene or phenylene remainder.

13. ) A method as claimed in claim 1, wherein cation Q⁺ is selected from the group comprising N-butylpyridinium, N-ethylpyridinium, pyridinium, ethyl-3-methyl-1-imidazolium, butyl-3-methyl-1-imidazolium, hexyl-3-methyl-1-imidazolium, butyl-3-dimethyl-1,2-imidazolium, diethyl-pyrazolium, N-butyl-N-methyl-pyrro-lidinium, trimethylphenylammonium, tetrabutylphosphonium, tributyltetradecyl-phosphonium.

14. ) A method as claimed in claim 1, wherein cation Q⁺ is of general formula [SR¹R²R³]⁺, where R¹, R² and R³ represent each a hydrocarbyl remainder having 1 to 12 carbon atoms.

15. ) A method as claimed in claim 1, wherein the ionic liquid is selected from the group comprising N-butyl-pyridinium hexafluorophosphate, N-ethyl-pyridinium tetrafluoroborate, pyridinium fluorosulfonate, butyl-3-methyl-1-imidazolium tetrafluoroborate, butyl-3-methyl-1-imidazolium bis-trifluoromethane-sulfonyl amidide, triethylsulfonium bis-trifluoromethane-sulfonyl amidide, butyl-3-methyl-1-imidazolium hexafluoro-antimonate, butyl-3-methyl-1-imidazolium hexa-fluorophosphate, butyl-3-methyl-1-imidazolium trifluoroacetate, butyl-3-methyl-1-imidazolium trifluoromethylsulfonate, butyl-3-methyl-1-imidazolium bis(trifluoro-methylsulfonyl)amidide, trimethyl-phenylammonium hexafluorophosphate, tetrabutylphosphonium tetrafluoroborate.