Regenerable solid imine sorbents
Two new classes of amine-based sorbents are disclosed. The first class comprises new polymer-immobilized tertiary amine sorbents; the second class new polymer-bound amine sorbents. Both classes are tailored to facilitate removal of acid anhydrides, especially carbon dioxide (CO 2 ), from effluent gases. The amines adsorb acid anhydrides in a 1:1 molar ratio. Both classes of amine sorbents adsorb in the temperature range from about 20° C. upwards to 90° C. and can be regenerated by heating upwards to 100° C.
1. A sorbent for acid anhydrides comprising:
a) a support substrate selected from the group consisting of polyethers, polystyrenes, siloxanes, polyacrylates, and combinations thereof;
b) a tertiary amine selected from the consisting of 1,8 Diazabicyclo-[5.4.0]-undec-7-ene (DBU); 1,3,4,6,7,8-Hexahydro-2H-pyrimido[1,2,-a]pyrimidine (TBD), and N-(2-Hydroxyethyl)piperazine immobilized within the pores of the substrate; and
c) wherein a 1:1 molar ratio of said acid anhydrides to the tertiary amine defines the maximum sorbent loading capacity.
2. The sorbent as recited in claim 1 wherein the acid anhydride is a gas selected from the group consisting of C0 2 , S0 2 , and NO x .
3. The sorbent as recited in claim 1 wherein the sorbent adsorbs said acid anhydrides in the temperature range from 20° C. to 85° C.
4. The sorbent as recited in claim 1 wherein the molar ratio of the support substrate to amine is between 2.5:1 and 5:1.
5. The sorbent as recited in claim 1 wherein the surface area of the sorbents range from 50 meters squared per gram (m 2 /g) to 1000 m 2 /g.
6. The sorbent as recited in claim 1 wherein the sorbents can be formed into a solid phase selected from the group consisting of extrudates, films, powders, pellets, or monoliths to accommodate various reactor configurations.
7. The sorbent as recited in claim 1 wherein the sorbent is regenerated by heating to at or above 90° C.
8. A sorbent for removing acid anhydrides from a flue gas stream comprising:
a) a support substrate selected from the group consisting of polyethers, polystyrenes, siloxanes, polyacrylates, and combinations thereof;
b) a tertiary amine selected from the consisting of acyclic imines, cyclic imines, acyclic amidines, cyclic amidines, acyclic guanidines, and cyclic guanidines immobilized within the pores; and,
c) wherein a 1:1 molar ratio of said acid anhydrides to the tertiary amine defines the maximum sorbent loading capacity.
9. The sorbent as recited in claim 8 wherein the acid anhydride is a gas selected from the group consisting of C0 2 , S0 2 , and NO x .
10. The sorbent as recited in claim 8 wherein the sorbent adsorbs acid anhydride in the temperature range from 20° C. to 85° C.
11. The sorbent as recited in claim 8 wherein the sorbent can be used in the pressure range from 5 Torr to 5 atmospheres (atm).
12. The sorbent as recited in claim 8 wherein the surface area of the sorbents ranges from of about 50 meters squared per gram (m 2 /g) to 1000 m 2 /g.
13. The sorbent as recited in claim 8 wherein the sorbents can be formed into a solid phase selected from the group of extrudates, films, powders, pellets, or monoliths to accommodate various configurations.
14. The sorbent as recited in claim 8 wherein the sorbent can be regenerated by heating to or above 90° C.
15. The sorbent of claim 1 wherein the amine is solid.
16. The sorbent of claim 1 wherein the amine has a boiling point above 100° C.
17. The sorbent of claim 1 wherein the sorbent retains the amine after exposure to anhydride.