Liquid carbon dioxide absorbent and methods of using the same

Abstract

A carbon dioxide absorbent comprising (i) a liquid, nonaqueous silicon-based material, functionalized with one or more groups that either reversibly react with CO 2 or have a high-affinity for CO 2 is provided and (ii) a hydroxy-containing solvent. The absorbent may be utilized in methods to reduce carbon dioxide in an exhaust gas, and finds particular utility in power plants.

1 . A carbon dioxide absorbent comprising: (i) a liquid, nonaqueous silicon-based material, functionalized with one or more groups that reversibly react with CO 2  and/or have a high-affinity for CO 2 ; and (ii) a hydroxy-containing solvent 
     
     
         2 . The absorbent of  claim 1 , wherein the functionalized silicon-based material comprises silanes, or compounds containing one or more siloxy units, or combinations of these. 
     
     
         3 . The absorbent of  claim 1 , wherein the silicon-based material is functionalized with one or more nitrogen-containing groups. 
     
     
         4 . The absorbent of  claim 3 , wherein the functional group(s) comprise(s) one or more aliphatic amines, imines, amidines, amides, heterocyclic amino compounds such as pyridine, aromatic amines such as aniline, and combinations of these. 
     
     
         5 . The absorbent of  claim 4 , wherein the functional group(s) comprise(s) one or more amines. 
     
     
         6 . The absorbent of  claim 5 , wherein the functional group(s) comprise(s)one or more di-, tri- and polyamines or combinations of these. 
     
     
         7 . The absorbent of  claim 6 , wherein the functional group(s) comprise(s) one or more aminomethyl, aminoethyl, aminopropyl, aminoethylaminopropyl, piperazinopropyl, aminomethylaminoethyl, 2-aminopropylpryidyl, groups or combinations of these. 
     
     
         8 . The absorbent of  claim 7 , wherein the functional group(s) comprise(s) one or more amino hydroxy groups. 
     
     
         9 . The absorbent of  claim 1 , wherein the said solvent has a vapor pressure below 150 mm Hg at 100° C. 
     
     
         10 . The absorbent of  claim 9 , wherein the said solvent comprises two or more hydroxyl groups. 
     
     
         11 . The absorbent of  claim 10 , wherein the said solvent comprises a glycol, a hydroxylated silicone, a phenol or combinations of these. 
     
     
         12 . The absorbent of  claim 11 , wherein the solvent comprises trimethylolpropane, glycerol, triethylene glycol, tetraethylene glycol, 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane, a hydrosilylation reaction product of 1,1,3,3-tetramethyldisiloxane and trimethylolpropane allyl ether, eugenol, isoeugenol, 2-allyl-6-methylphenol or combinations of these. 
     
     
         13 . The absorbent of  claim 1 , further comprising water. 
     
     
         14 . The absorbent of  claim 1 , further comprising antioxidants, stabilizers, accelerators, antifoaming agents or blends thereof. 
     
     
         15 . A method for reducing the amount of carbon dioxide in a process stream comprising contacting the stream with a carbon dioxide absorbent comprising (i) a liquid, nonaqueous silicon-based material, functionalized with one or more groups that reversibly react with CO 2  and/or have a high-affinity for CO 2 ; and (ii) a hydroxy-containing solvent. 
     
     
         16 . The method of  claim 15 , wherein the process stream comprises an exhaust stream. 
     
     
         17 . The method of  claim 15 , wherein the hydroxy-containing solvent comprises trimethylolpropane, glycerol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene, 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane, a hydrosilylation reaction product of 1,1,3,3-tetramethyldisiloxane and trimethylolpropane allylether, or combinations of these. 
     
     
         18 . The method of  claim 15 , wherein the carbon dioxide solvent further comprises water. 
     
     
         19 . The method of  claim 15 , wherein the functionalized silicon-based material comprises one or more aminosilicones. 
     
     
         20 . The method of  claim 15 , wherein the functional group(s) comprise(s) one or more amines. 
     
     
         21 . The method of  claim 20 , wherein the functional group(s) comprise(s) one or more di-, tri- and polyamines or combinations of these. 
     
     
         22 . A power plant comprising a carbon dioxide removal unit further comprising a carbon dioxide absorbent comprising (i) a liquid, nonaqueous silicon-based material, functionalized with one or more groups that reversibly react with CO 2  and/or have a high-affinity for CO 2 ; and (ii) a hydroxy-containing solvent. 
     
     
         23 . A method of generating electricity with reduced carbon dioxide emissions comprising combusting a fuel to produce an exhaust gas comprising carbon dioxide and directing the exhaust gas to a carbon dioxide removal unit comprising a carbon dioxide absorbent comprising (i) a liquid, nonaqueous silicon-based material, functionalized with one or more groups that reversibly react with CO 2  and/or have a high-affinity for CO 2 ; and (ii) a hydroxy-containing solvent. 
     
     
         24 . The method of  claim 23 , wherein the hydroxyl-containing solvent comprises trimethylolpropane, glycerol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene, 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane, a hydrosilylation reaction product of 1,1,3,3-tetramethyldisiloxane and trimethylolpropane allylether, or combinations of these. 
     
     
         25 . The method of  claim 23 , wherein the absorbent further comprises water. 
     
     
         26 . The method of  claim 23 , wherein the functionalized silicon-based material comprises one or more silicones. 
     
     
         27 . The method of  claim 26 , wherein the functional group(s) comprise(s) one or more amines.