Co2 sorption by supported amino acid ionic liquids

Abstract

The present invention concerns the absorption and desorption behaviour of carbon dioxide (CO 2 ) using ionic liquids derived from amino acids adsorbed on porous carrier materials.

1 . A composition for absorption/desorption of gaseous carbon dioxide (CO 2 ), which comprises an ionic compound [A + ][B − ] and a porous material, wherein
 [A + ] is an ammonium ion of Formula I   
       
         
           
           
               
               
           
         
         wherein R 1 , R 2 , R 3  and R 4  are individually selected from linear or branched C n  alkyl chains where n is an integer having a value of at least 4 and not more than 30, and wherein 
         [B − ] is an anion of Formula II: 
       
       
         
           
           
               
               
           
         
         wherein R 5  is selected from hydrogen or a C 1 -C 6  linear or branched alkyl group, and G can be hydrogen or a group of Formula III: 
       
       
         
           
           
               
               
           
         
         
           wherein
 R 6  is selected from hydrogen or a C 1 -C 6  linear or branched alkyl group; 
 R 7  can be a C 1 -C 6  linear or branched alkyl group or an aromatic group, and 
 when R 5  is hydrogen, R 7  may further also be attached to the nitrogen atom to which R 5  is attached, thereby forming a 4-7 membered ring together with said nitrogen. 
 
         
       
     
     
         2 . A composition according to  claim 1  wherein the ionic compound [A + ][B − ] comprises an anion of one of the following amino acids: 
       
         
           
           
               
               
           
         
       
     
     
         3 . A composition according to  claim 1  wherein the ionic compound [A + ][B − ] comprises one of the following ammonium ions: 
       
         
           
           
               
               
           
         
       
     
     
         4 . A composition according to any one of the preceding claims wherein the porous material is selected from porous (including mesoporous) inorganic, carbonaceous or a polymeric materials such as, but not limited to, silica, including mesoporous silica, controlled pore glass, alumina, titania (anatase), zirconia, alkaline earth metal oxides, clays and zeolites, or mixtures hereof. 
     
     
         5 . A composition according to any one of the preceding claims which contains between 5-45% w/w of the ionic compound [A + ][B − ], such as 10% w/w, 20% w/w, 30% w/w or 40% w/w. 
     
     
         6 . A composition according to any one of the preceding claims which contains between 5-45% w/w, such as 10% w/w, 20% w/w, 30% w/w or 40% w/w, of an ionic compound selected from [N4444][Met], [N6666][Ile], [N6666][Gly], [N6666][Asn], [N6666][Pro] and [N6666][Tyr]. 
     
     
         7 . A composition according to  6  which contains 40% w/w of an ionic compound selected from [N6666][Ile], [N6666][Gly] and [N6666][Pro]. 
     
     
         8 . A method for absorption of gaseous CO 2  from a gas stream, which method comprises contacting said gas stream with a composition according to any one of the preceding claims. 
     
     
         9 . A method for absorption of gaseous CO 2  from a gas stream according to  claim 8 , wherein the absorption takes place from a gas stream which contains 1-100 mol % CO 2  with an absorption capacity of over 1 mol CO 2 /mol of the ionic compound [A + ][B − ]. 
     
     
         10 . The method according to any one of  claims 8 - 9  wherein the contact between the gas stream and the composition takes place in a suitable reactor such as a fixed-bed or movable-bed reactor using an appropriately shaped form of the composition which provides low resistance to the gas stream and an acceptable pressure drop across the reactor. 
     
     
         11 . The method according to any one of  claims 8 - 10  wherein the gas stream is a flue-gas stream generated from combustion by large point stationary sources such as power plants. 
     
     
         12 . A method for desorption of CO 2  absorbed on a composition according to any one of  claims 1 - 7 , which method comprises increasing the temperature of the composition and/or decreasing the total pressure surrounding it and/or by flushing it with a gas stream with no or lower CO 2  content than the gas stream originally applied for the absorption.