Process for removing carbon dioxide containing acidic gases from gaseous mixtures using a basic salt activated with a hindered amine
First Claim
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1. In a process for removing CO2 from gaseous feeds containing CO2, which comprises:
- (1) contacting said gaseous feeds with an aqueous scrubbing solution comprising;
(a) an alkaline material comprising a basic alkali metal salt or alkali metal hydroxide, (b) an activator for said basic alkali metal salt or alkali metal hydroxide comprising at least one amine activator for said alkaline material, and (c) water, and(2) regenerating said aqueous scrubbing solution at conditions whereby CO2 is desorbed from said aqueous scrubbing solution, the improvement which comprises providing at least one sterically hindered amine as at least one of the amine activators, and operating said process at conditions whereby the difference between the moles of carbon dioxide absorbed at the end of step (1) (absorption step) and the moles of carbon dioxide absorbed at the end of step (2) (desorption step) would be greater at the thermodynamic equilibrium (as determined from the vapor-liquid equilibrium isotherm of the reaction mixture) than in an aqueous scrubbing process wherein diethanolamine is the only amine activator utilized under similar conditions of gaseous feed composition, scrubbing solution composition, temperatures and pressures.
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Abstract
Carbon dioxide containing acidic gases are removed from a normally gaseous mixture by a process comprising contacting the normally gaseous mixture with an aqueous solution comprising (a) a basic alkali metal salt or hydroxide and (b) an activator for said basic salt or alkali metal salt or hydroxide comprising at least one sterically hindered amine.
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Citations
39 Claims
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1. In a process for removing CO2 from gaseous feeds containing CO2, which comprises:
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(1) contacting said gaseous feeds with an aqueous scrubbing solution comprising;
(a) an alkaline material comprising a basic alkali metal salt or alkali metal hydroxide, (b) an activator for said basic alkali metal salt or alkali metal hydroxide comprising at least one amine activator for said alkaline material, and (c) water, and(2) regenerating said aqueous scrubbing solution at conditions whereby CO2 is desorbed from said aqueous scrubbing solution, the improvement which comprises providing at least one sterically hindered amine as at least one of the amine activators, and operating said process at conditions whereby the difference between the moles of carbon dioxide absorbed at the end of step (1) (absorption step) and the moles of carbon dioxide absorbed at the end of step (2) (desorption step) would be greater at the thermodynamic equilibrium (as determined from the vapor-liquid equilibrium isotherm of the reaction mixture) than in an aqueous scrubbing process wherein diethanolamine is the only amine activator utilized under similar conditions of gaseous feed composition, scrubbing solution composition, temperatures and pressures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 14, 15, 17, 18, 20, 22, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39)
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8. 2-dimethyl-diethylenetriamine;
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N1 -tert. butyl-1,2,3-triaminopropane; 2,2,5,5-tetramethyldiethylenetriamine; 1-amino-1-aminomethyl-2-hydroxymethylcyclohexane; N-hydroxyethyl-1,2-diaminocyclohexane; N-cyclohexyl-1,3-diamino-2-propanol; N-(2-hydroxycyclohexyl)-1,3-propanediamine; N-isopropanol-1,2-diaminocyclohexane; N-(2-hydroxybutyl)-1,4-diaminocyclohexane; N1 (1-hydroxy-2-butyl)-2-methyl-1,2-propanediamine; N(1-hydroxy-2-methyl-2-butyl)-1,3-propanediamine; N1 (1,1-dimethyl-2-hydroxyethyl)-2-methyl-1,2-propanediamine; N3 -isobutyl-2-methyl-2,3-diamino-1-propanol; N(3-hydroxy-2-butyl)-2,3-diaminobutane; N1 -hydroxyethyl-2-methyl-1,2-propanediamine; 2,N3,N3 -trimethyl-2,3-diamino-1-propanol; N1,2-dimethyl-N1 -hydroxyethyl-1,2-propanediamine; N(1,1-dimethyl-2-hydroxyethyl)-1,3-propanediamine; N-tert. butyl-1,3-diamino-2-propanol; 3-amino-3-methyl-2-pentanol; 1-hydroxymethyl-cyclopentylamine; 2,3-dimethyl-3-amino-1-butanol; 2-amino-2-ethyl-1-butanol; 1-methyl-2-hydroxycyclopentylamine; 2-amino-2-methyl-3-pentanol; 2,4-dimethyl-2-amino cyclohexanol; 1-hydroxyethyl cyclohexylamine; 1-hydroxymethyl-3-methyl cyclohexylamine; 2-hydroxymethyl-1-methyl-cyclohexylamine; 2-amino-2-methyl-1-propanol; 2-amino-2-methyl-1-butanol; 3-amino-3-methyl-1-butanol; 3-amino-3-methyl-2-butanol; 2-amino-2,3-dimethyl-3-butanol; 2-amino-2,3-dimethyl-1-butanol; 1-hydroxymethylcyclohexylamine; 2(2-amino-2-methylpropoxy)-ethanol; 2-piperidine methanol; 2-piperidine ethanol; 2-(1-hydroxyethyl)-piperidine; 5-hydroxy-2-methyl piperidine; 2-methyl-3-hydroxy piperidine; 2,6-dimethyl-3-hydroxy piperidine; 2,5-dimethyl-4-hydroxy piperidine; 2-tert. butylamino-methyl-1,4-dimethyl-piperazine; 1-tert. butylamino-3,6-dimethyl-3,6-diaza-cycloheptane; and N-cyclohexyl-beta-alanine.
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13. A process for removing CO2 from gaseous feeds containing CO2 which comprises contacting said feed with an aqueous solution comprising (a) potassium carbonate in an amount ranging from about 10 to about 40 weight percent, (b) at least about 2 weight percent of an amine activator comprising a sterically hindered amine selected from the group consisting of:
- N-cyclohexyl-1,3-propanediamine;
1,8-menthanediamine;
1,7-bis-sec-butyl-diethylenetriamine;
2,2,5,5-tetramethyl diethylenetriamine;
3-amino-3-methyl-1-butanol;
2-amino-2-methyl-1-propanol, N1 -isopropyl-2-methyl-1,2-propanediamine;
N1 (1,1-dimethyl-2-hydroxyethyl)-2-methyl-1,2-propanediamine; and
N1 -isopropyl-N2 -(3-aminopropyl)-2-methyl-1,2-propanediamine.
- N-cyclohexyl-1,3-propanediamine;
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16. A process for removing CO2 from gaseous feeds containing CO2 which comprises contacting said feed with an aqueous solution comprising:
- (a) potassium carbonate in an amount ranging from about 10 to about 40 weight percent, (b) at least 2 weight percent of an amine activator comprising N-cyclohexyl-1,3-propanediamine and (c) water.
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19. In a process for removing carbon dioxide from gaseous feeds containing carbon dioxide which comprises, in sequential steps:
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(1) contacting said feed with an aqueous scrubbing solution comprising;
(a) an alkaline material comprising a basic alkali metal salt or alkali metal hydroxide in an amount ranging from about 10 to about 40 weight percent, (b) at least 2 weight percent of an amine activator, and (c) water, at conditions whereby said carbon dioxide is absorbed in said scrubbing solution, and(2) regenerating said scrubbing solution at conditions whereby carbon dioxide is desorbed from said scrubbing solution, the improvement which comprises providing a sterically hindered amine as an amine activator, and operating said process at conditions whereby the difference between the moles of carbon dioxide absorbed at the end of step (1)(absorption step) and the moles of carbon dioxide absorbed at the end of step (2)(desorption step) would be greater at the thermodynamic equilibrium (as determined from the vapor-liquid equilibrium isotherm of the reaction mixture) than in an aqueous scrubbing process wherein diethanolamine or 1,6-hexanediamine is the only amine activator utilized under similar conditions of gaseous feed composition, scrubbing solution composition, temperatures and pressures. - View Dependent Claims (21, 23)
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34. In a process for removing CO2 from gaseous feeds containing CO2 which comprises, in sequential steps:
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(1) contacting said feed with an aqueous scrubbing solution comprising (a) from about 20 to about 35 weight percent of potassium carbonate, (b) from about 2 to about 20 weight percent of an amine activator, and (c) water, at conditions whereby said CO2 is absorbed in said scrubbing solution; (2) regenerating said scrubbing solution at conditions whereby carbon dioxide is desorbed from said scrubbing solution, the improvement which comprises providing an asymmetrical sterically hindered cycloaliphatic diamine as an amine activator wherein the sterically hindered cycloaliphatic diamine is defined as a compound having a boiling point of at least 80°
C. and containing at least one secondary amino group attached to a secondary carbon atom.
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Specification