Carbon dioxide adsorbents

Abstract

A carbon dioxide adsorbent including a hierarchical zeolite. The hierarchical zeolite defines micropores having a pore width between about 0.4 nm and about 2 nm, and at least one of: mesopores having a pore width between about 2 nm and about 50 nm; and macropores having a pore width greater than about 50 nm.

1 - 40 . (canceled) 
     
     
         41 . A method of forming a geopolymer resin, the method comprising:
 combining sodium hydroxide, water glass, and water to yield a first mixture;   allowing the first mixture to cool to yield a solution;   combining metakaolin with the solution to yield a second mixture; and   homogenizing the second mixture to yield a geopolymer resin.   
     
     
         42 . The method of  claim 41 , further comprising combining canola oil with the second mixture to yield the geopolymer resin. 
     
     
         43 . The method of  claim 42 , wherein the first mixture comprises about 1 part by weight sodium hydroxide, about 2-3 parts by weight water glass, about 1 part by weight water, and about 1 part by weight canola oil. 
     
     
         44 . The method of  claim 41 , wherein the first mixture comprises about 1 part by weight of the sodium hydroxide, about 2-3 parts by weight water glass, and about 1-2 parts by weight water. 
     
     
         45 . The method of  claim 41 , wherein the second mixture comprises about 1 part by weight sodium hydroxide, about 2-3 parts by weight water glass, about 1-2 parts by weight water, and about 1-2 parts by weight metakaolin. 
     
     
         46 . The method of  claim 41 , wherein homogenizing the second mixture comprises stirring. 
     
     
         47 . The method of  claim 41 , wherein the geopolymer resin comprises Na 2 O, Al 2 O 3 , SiO 2 , and H 2 O in a molar ratio of about 3:1:4:32. 
     
     
         48 . The method of  claim 41 , further comprising heating the geopolymer resin to yield a paste. 
     
     
         49 . The method of  claim 48 , the heating comprises heating at a temperature of about 60° C. to about 90° C. 
     
     
         50 . The method of  claim 48 , further comprising dispersing the paste in water to yield a first dispersion. 
     
     
         51 . The method of  claim 50 , further comprising purifying the paste by centrifuging the dispersion to yield a precipitate and redispersing the precipitate in water to yield a second dispersion. 
     
     
         52 . The method of  claim 41 , wherein the second dispersion has a neutral pH. 
     
     
         53 . The method of  claim 52 , further comprising collecting a precipitate from the dispersion. 
     
     
         54 . The method of  claim 53 , further comprising drying the precipitate to yield a hierarchical zeolite. 
     
     
         55 . The method of  claim 54 , wherein the hierarchical zeolite has a ratio of silicon atoms to aluminum atoms up to about 3. 
     
     
         56 . The method of  claim 55 , wherein the hierarchical zeolite has a ratio of silicon atoms to aluminum atoms up to about 2. 
     
     
         57 . The method of  claim 56 , wherein the hierarchical zeolite has a ratio of silicon atoms to aluminum atoms up to about 1.5. 
     
     
         58 . The method of  claim 54 , further comprising at least partially ion-exchanging the hierarchical zeolite with an alkali metal ion, an alkaline earth metal ion, a rare earth metal ion, a transition metal ion, or a combination thereof. 
     
     
         59 . The method of  claim 54 , wherein the hierarchical zeolite defines mesopores. 
     
     
         60 . The method of  claim 54 , wherein the hierarchical zeolite has a crystallinity not lower than 80%.