Carbon dioxide absorbent and method of using the same
View Patent ↗In accordance with one aspect, the present invention provides an amino-siloxane composition comprising at least one of structures I, II, III, IV or V said compositions being useful for the capture of carbon dioxide from gas streams such as power plant flue gases. In addition, the present invention provides methods of preparing the amino-siloxane compositions are provided. Also provided are methods for reducing the amount of carbon dioxide in a process stream employing the amino-siloxane compositions of the invention as species which react with carbon dioxide to form an adduct with carbon dioxide. The reaction of the amino-siloxane compositions provided by the present invention with carbon dioxide is reversible and thus, the method provides for multicycle use of said compositions.
1. An amino-siloxane composition comprising structure I
wherein R 1 is independently at each occurrence C 1 -C 5 alkyl; R 2 is hydrogen or C 1 -C 3 acyl; R 3 is a bond, hydrogen or C 1 -C 5 alkyl; R 4 is C 1 -C 5 alkyl or R 5 ; and R 5 is independently at each occurrence a C 1 -C 30 aliphatic radical comprising at least one NH 2 group or secondary amine group.
2. The composition according to claim 1 having structure Ia
3. The composition according to claim 1 having structure Ib
4. An amino-siloxane composition comprising structure II
wherein R 1 is independently at each occurrence C 1 -C 5 alkyl; R 2 is hydrogen or C 1 -C 3 acyl; R 3 is a bond, hydrogen, or C 1 -C 5 alkyl; R 4 is C 1 -C 5 alkyl or R 5 ; R 5 is independently at each occurrence a C 1 -C 30 aliphatic radical comprising at least one NH 2 group or secondary amine group; and n is independently at each occurrence 1-3.
5. The composition according to claim 4 having structure IIa
6. The composition according to claim 4 having structure IIb
7. A method of preparing an amino-siloxane composition having structure 3; said method comprising contacting a siloxysilyl oxirane having structure 1 with an organic amine having structure 2
wherein R 1 is independently at each occurrence C 1 -C 5 alkyl; and R 5 is a C 1 -C 30 aliphatic radical comprising at least one NH 2 group or secondary amine group, and R 7 is a C 1 -C 30 aliphatic radical or a C 2 -C 30 cycloaliphatic radical.
8. The method according to claim 7 , wherein siloxysilyl oxirane has structure 1a
9. A method of reducing the amount of carbon dioxide in a process stream comprising contacting the stream with a carbon dioxide absorbent comprising at least one amino-siloxane selected from the group consisting of amino-siloxanes having structure I, and amino-siloxanes having structure II
wherein R 1 is independently at each occurrence C 1 -C 5 alkyl; R 2 is hydrogen or C 1 -C 3 acyl; R 3 is independently at each occurrence a bond, hydrogen or C 1 -C 5 alkyl; R 4 is C 1 -C 5 alkyl or R 5 ; R 5 is independently at each occurrence a C 1 -C 30 aliphatic radical comprising at least one NH 2 group or secondary amine group; R 5 is independently at each occurrence a C 1 -C 30 aliphatic radical comprising at least one NH 2 group or a secondary amine group; and n is independently at each occurrence 1-3.
10. The method according to claim 9 , wherein the amino-siloxane is a liquid.
11. The method according to claim 9 , wherein said process stream is a by-product from coal combustion.