Modified zeolites that include amine-containing organometallic moieties and methods for making such
Disclosed herein are modified zeolites and methods for making modified zeolites. In one or more embodiments disclosed herein, a modified zeolite includes a microporous framework including a plurality of micropores having diameters of less than or equal to 2 nm and organometallic moieties each bonded to bridging oxygen atoms. The microporous framework includes at least silicon atoms and oxygen atoms. The organometallic moieties include a metal atom and a ring structure including the metal atom, a nitrogen atom, and one or more carbon atoms. The metal atom may be bonded to a bridging oxygen atom, and wherein the bridging oxygen atom bridges the metal atom of the organometallic moiety and a silicon atom of the microporous framework.
1. A modified zeolite comprising:
a microporous framework comprising a plurality of micropores having diameters of less than or equal to 2 nm, wherein the microporous framework comprises at least silicon atoms and oxygen atoms; and
organometallic moieties each bonded to bridging oxygen atoms, wherein the organometallic moieties comprise:
a metal atom, wherein the metal atom is bonded to a bridging oxygen atom, and wherein the bridging oxygen atom bridges the metal atom of the organometallic moiety and a silicon atom of the microporous framework; and
a ring structure comprising the metal atom, a nitrogen atom, and one or more carbon atoms.
2. The modified zeolite of claim 1 , further comprising a plurality of mesopores having diameters of greater than 2 nm and less than or equal to 50 nm.
3. The modified zeolite of claim 1 , wherein the average pore size of the modified zeolite is greater than 2 nm.
4. The modified zeolite of claim 1 , wherein the modified zeolite comprises particles of from 25 nm to 900 nm in size.
5. The modified zeolite of claim 1 , wherein the modified zeolite is a ZSM-5 zeolite.
6. The modified zeolite of claim 1 , wherein the microporous framework further comprises aluminum atoms.
7. The modified zeolite of claim 1 , wherein the metal atom is titanium.
8. The modified zeolite of claim 1 , wherein the ring structure consists of the metal atom, a nitrogen atom, and one carbon atom.
9. The modified zeolite of claim 1 , wherein the organometallic moieties further comprise:
an amino group bonded to the metal atom; and
a secondary amine coordinated with the metal atom.
10. The modified zeolite of claim 9 , wherein:
the amino group may be any of a dimethylamino group, a diethylamino group, or a methylethylamino group; and
the secondary amine may be any of dimethylamine, diethylamine, or methylethylamine.
11. A method for making a modified zeolite, the method comprising:
reacting an organometallic chemical with a dehydroxylated zeolite, wherein the dehydroxylated zeolite comprises a microporous framework comprising a plurality of micropores having diameters of less than or equal to 2 nm, wherein the microporous framework comprises at least silicon atoms and oxygen atoms, and wherein the dehydroxylated zeolite comprises isolated terminal silanol functionalities comprising hydroxyl groups bonded to silicon atoms of the microporous framework;
wherein the reacting of the organometallic chemical with the dehydroxylated zeolite forms the modified zeolite comprising organometallic moieties each bonded to bridging oxygen atoms, wherein the organometallic moieties comprise:
a metal atom, wherein the metal atom is bonded to a bridging oxygen atom, and wherein the bridging oxygen atom bridges the metal atom of the organometallic moiety and a silicon atom of the microporous framework; and
a ring structure comprising the metal atom, a nitrogen atom, and one or more carbon atoms,
wherein the organometallic moiety comprises a portion of the organometallic chemical; and
wherein the organometallic chemical comprises one or more amine moieties, wherein the nitrogen atom of the amine moieties are bonded with the metal atom of the organometallic chemical.
12. The method of claim 11 , wherein the modified zeolite comprises a plurality of mesopores having diameters of greater than 2 nm and less than or equal to 50 nm.
13. The method of claim 11 , wherein the average pore size of the modified zeolite is greater than 2 nm.
14. The method of claim 11 , further comprising dehydroxylating an initial zeolite to form the dehydroxylated zeolite, wherein the initial zeolite primarily comprises vicinal silanol functionalities, and wherein dehydroxylating the initial zeolite forms the isolated terminal silanol functionalities.
15. The method of claim 14 , wherein one or more of:
dehydroxylating the initial zeolite comprises heating the initial zeolite at a temperature of 650° C. to 1100° C.; and
dehydroxylating the initial zeolite is under reduced pressure.
16. The method of claim 11 , wherein the microporous framework further comprises aluminum atoms.
17. The method of claim 11 , wherein the average pore size of the dehydroxylated zeolite is greater than the size of the organometallic chemical.
18. The method of claim 11 , wherein the organometallic chemical comprises MR 1 R 2 R 3 R 4 , wherein:
M is a metal atom;
R 1 is any of a dimethylamino group, a diethylamino group, or a methylethylamino group;
R 2 is any of a dimethylamino group, a diethylamino group, or a methylethylamino group;
R 3 is any of a dimethylamino group, a diethylamino group, or a methylethylamino group; and
R 4 is any of a dimethylamino group, a diethylamino group, or a methylethylamino group.
19. The method of claim 11 , wherein the metal atom is titanium.