Carbon dioxide capture process using hydrogels
The present application is directed to processes for removing carbon dioxide (CO 2 ) from low CO 2 concentration gaseous streams. The process comprises contacting the gaseous stream with a hydrogel for absorbing at least some CO 2 from the gaseous stream. The hydrogel comprises a cross-linked hydrophilic polymer comprising a hydrophilic polymer cross-linked with a cross-linking agent. Processes for preparing the hydrogel, types of hydrogels, using the hydrogel to remove CO 2 from gaseous streams, and regenerating the hydrogel to recover absorbed CO 2 from the hydrogel are also disclosed.
1 . A direct air capture (DAC) process for removing carbon dioxide (CO 2 ) from an ambient air stream, comprising:
contacting the ambient air stream with a swollen hydrogel to absorb CO 2 from the ambient air stream resulting in an effluent air stream,
wherein the swollen hydrogel comprises a cross-linked polyamine or copolymer thereof, wherein the polyamine or copolymer thereof is cross-linked with a cross-linking agent to provide a polymeric network comprising amine groups for absorbing at least some of the CO 2 , wherein the cross-linking agent comprises two or more epoxides, and
wherein the swollen hydrogel is swollen with a liquid swelling agent selected from the group consisting of alcohols, polyol compounds, glycols, alkanolamines, alkylamines, alkyloxyamines, piperidines, piperazines, pyridines, pyrrolidones, polyethylene glycol-dimethyl ethers (Selexol), N-methylpyrrolidone, propylene carbonate, sulfolane, imidazoles, ionic liquids, and combinations thereof, for absorbing at least some of the CO 2 .
2 . The process according to claim 1 , wherein the polyamine is a polyalkylenimine.
3 . The process according to claim 2 , wherein the polyalkylenimine is polyethylenimine (PEI).
4 . The process according to claim 1 , wherein the cross-linking agent is a diepoxide or a triepoxide.
5 . The process according to claim 1 , wherein the swollen hydrogel has a swelling capacity of about 20 g/g to about 100 g/g of liquid swelling agent.
6 . The process according to claim 1 , wherein the swollen hydrogel comprises about 40 wt. % to about 99 wt. % liquid swelling agent.
7 . The process according to claim 1 , wherein the liquid swelling agent is selected from the group consisting of alcohols, polyol compounds, glycols, alkanolamines, alkylamines, alkyloxyamines, piperidines, piperazines, pyridines, pyrrolidones, and combinations thereof.
8 . The process according to claim 1 , wherein the liquid swelling agent is selected from the group consisting of monoethylene glycol, polyethyleneglycol, glycerol, 2-methoxyethanol, 2-ethoxyethanol, monoethanolamine, diethanolamine, methyldiethanolamine, diisopropanolamine, and aminoethoxyethanol, and combinations thereof.
9 . The process according to claim 1 , wherein the contacting the ambient air stream with the hydrogel comprises passing the ambient air stream through a bed comprising the swollen hydrogel.
10 . The process according to claim 1 , wherein the process further comprises a regeneration recovery process to desorb the absorbed CO 2 from the swollen hydrogel.
11 . The process according to claim 10 , wherein the regeneration recovery process comprises desorbing at least a portion of the absorbed CO 2 from the swollen hydrogel by heating, pressure reduction, or a combination thereof.
12 . The process of claim 1 , wherein the swollen hydrogel has a CO 2 absorption capacity (in mg CO 2 per g of hydrogel; mg/g) of between 10 to 300.
13 . The process of claim 1 , wherein the ambient air stream has a flow rate of at least about 100 cm 3 /min to about to 100,000 cm 3 /min.
14 . The process of claim 1 , wherein the swollen hydrogel is provided as a film or coating layer, and contacting the ambient air stream with the swollen hydrogel film or coating layer comprises passing the ambient air stream thereon or through the film or coating layer.
15 . The process of claim 14 , wherein the swollen hydrogel film or coating layer is supported on or within a porous support, and contacting the ambient air stream with the swollen hydrogel film or coating layer comprises passing the ambient air stream through the porous support comprising the swollen hydrogel film or coating layer.
16 . The process of claim 15 , wherein the porous support is a monolith comprising a plurality of porous channels which are coated with the swollen hydrogel film or coating layer.
17 . The process of claim 1 , wherein the swollen hydrogel is a particulate.
18 . The process of claim 4 , wherein the cross-linking agent is 1,3-butadiene diepoxide (BDDE) or triglycidyl trimethylolpropane ether (TTE).
19 . The process of claim 1 , wherein the liquid swelling agent is a glycol.
20 . The process of claim 1 , wherein the liquid swelling agent is a primary amine, a secondary amine, a tertiary amine, or combinations thereof.
21 . The process of claim 1 , wherein the liquid swelling agent is a sterically hindered amine.