Regenerative adsorbents of modified amines on solid supports

Abstract

The invention relates to regenerative, solid sorbents for adsorbing carbon dioxide from a gas mixture, including air, with the sorbent including a modified polyamine and a solid support. The modified polyamine is the reaction product of an amine and an epoxide. The sorbent provides structural integrity, as well as high selectivity and increased capacity for efficiently capturing carbon dioxide from gas mixtures, including the air. The sorbent is regenerative, and can be used through multiple cycles of adsorption-desorption.

What is claimed is: 
     
         1 . A solid carbon dioxide sorbent with structural integrity for adsorbing carbon dioxide from a gas mixture, comprising a modified polyamine which is supported upon and within a solid support, wherein the modified polyamine is a reaction product of an excess of an amine selected from the group consisting of tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, triethylenetetramine, diethylenetriamine, polyethylenimine and a mixture thereof, and a diepoxide, a triepoxide, a polyepoxide, and a polymeric epoxide to provide a material with amine functionalities, wherein the solid support is (a) a nano-structured support of silica, silica-alumina, alumina, titanium oxide, calcium silicate, carbon nanotubes, carbon, or a mixture thereof and having a primary particle size of less than about 100 nm; or (b) a natural or synthetic clay or a mixture thereof. 
     
     
         2 . The carbon dioxide sorbent according to  claim 1 , in which the modified polyamine is present in an amount of 1% to 90% by weight of the sorbent, or in an approximately equal amount by weight as the support. 
     
     
         3 . The carbon dioxide sorbent according to  claim 1 , which further comprises a polyethylene oxide or a polyol or various mixtures thereof in an amount of 1 up to about 25% by weight of the sorbent, wherein the polyol is glycerol, oligomers of ethylene glycol or polyethylene glycol, and the polyethylene oxides may be present as their corresponding ethers. 
     
     
         4 . The carbon dioxide sorbent according to  claim 1  in which the modified polyamine is bound to the surface of the support by grafting methods with various species. 
     
     
         5 . The carbon dioxide sorbent according to  claim 1 , which has a high surface area for solid-gas contact, wherein the carbon dioxide sorbent is regenerative for capturing and separating carbon dioxide for at least one cycle at temperatures of 85° C. or less from a gas containing carbon dioxide. 
     
     
         6 . The carbon dioxide sorbent according to  claim 1 , which has a high surface area for solid-gas contact, wherein the carbon dioxide sorbent is regenerative for capturing and separating carbon dioxide for at least one cycle at temperatures of 55° C. or less from a gas containing carbon dioxide. 
     
     
         7 . The carbon dioxide sorbent according to  claim 1 , wherein the solid support has a primary particle size of between 3 and 50 nm. 
     
     
         8 . The carbon dioxide sorbent according to  claim 1 , wherein the solid support has a primary particle size of between 3 and 30 nm. 
     
     
         9 . The carbon dioxide sorbent according to  claim 1 , wherein the solid support has a primary particle size of between 3 and 15 nm. 
     
     
         10 . The carbon dioxide sorbent according to  claim 1 , wherein the modified polyamine is present in an amount of 1% to 70% by weight of the sorbent, or in an approximately equal amount by weight as the support. 
     
     
         11 . The carbon dioxide sorbent according to  claim 1 , wherein the modified polyamine is present in an amount of 1% to 40% by weight of the sorbent, or in an approximately equal amount by weight as the support. 
     
     
         12 . The carbon dioxide sorbent according to  claim 1 , wherein the natural or synthetic clay or a mixture thereof comprises montmorillonite. 
     
     
         13 . The carbon dioxide sorbent according to  claim 1 , which has a high surface area for solid-gas contact, wherein the carbon dioxide sorbent is regenerative for capturing and separating carbon dioxide for at least one cycle at temperatures of 55° C. or less from air or a gas mixture containing carbon dioxide in a concentration below 1 percent by volume. 
     
     
         14 . The carbon dioxide sorbent according to  claim 1 , which has a high surface area for solid-gas contact, wherein the carbon dioxide sorbent is regenerative for capturing and separating carbon dioxide for at least one cycle at temperatures of 55° C or less from ambient air with carbon dioxide concentrations between 200 ppm and 5000 ppm by volume.