Ionic liquids for separation of olefin-paraffin mixtures
The invention is directed to an ionic liquid comprising (i) a cationic portion containing a complex of a silver (I) ion and one or more neutral ligands selected from organoamides, organoamines, olefins, and organonitriles, and (ii) an anionic portion having the chemical formula wherein m and n are independently 0 or an integer of 1 or above, and p is 0 or 1, provided that when p is 0, the group —N—SO 2 —(CF 2 ) n CF 3 subtended by p is replaced with an oxide atom connected to the shown sulfur atom. The invention is also directed to a method for separating an olefin from an olefin-paraffin mixture by passing the mixture through a layer of the ionic liquid described above.
1. An ionic liquid comprising (i) a cationic portion containing a complex of a silver (I) ion and one or more organoamide neutral ligands, and (ii) an anionic portion having the chemical formula
wherein m and n are independently 0 or an integer of 1 or above, and p is 0 or 1, provided that when p is 0, the group —N—SO 2 —(CF 2 ) n CF 3 subtended by p is replaced with an oxide atom connected to the sulfur atom, and when p is 1, the shown perfluoroalkyl groups can optionally crosslink to form a cyclic anion;
further provided that N,N-dimethylbenzamide is excluded from said organoamides.
2. The ionic liquid of claim 1 , wherein the organoamide neutral ligands have a chemical formula within the following generic formula:
wherein R 1 and R 2 are independently selected from a hydrogen atom or a hydrocarbon group containing at least one and up to six carbon atoms, and R 3 is selected from a hydrogen atom or a hydrocarbon group containing at least one and up to twelve carbon atoms.
3. The ionic liquid of claim 2 , wherein the organoamide neutral ligands have a chemical formula within the following generic formula:
wherein R 1 and R 2 are independently selected from a hydrogen atom or a hydrocarbon group containing at least one and up to six carbon atoms; R 4 is a hydrocarbon group containing at least one and up to six carbon atoms, wherein a hydrocarbon group of R 4 can optionally form a fused ring to the shown phenyl ring; and subscript r can be a value of 0 to 5 to indicate, respectively, 0 to 5 R 4 groups present on any one or more carbon atoms of the shown phenyl ring.
4. The ionic liquid of claim 2 , wherein R 1 , R 2 , and R 3 are independently selected from a hydrogen atom or a hydrocarbon group containing at least one and up to six carbon atoms, wherein R 3 does not contain a phenyl ring directly bound to the shown carboxamide group.
5. The ionic liquid of claim 1 , wherein said anionic portion has the chemical formula:
wherein m and n are independently 0 or an integer of 1 or above.
6. The ionic liquid of claim 5 , wherein m and n are independently a number from 0 to 11.
7. The ionic liquid of claim 5 , wherein m and n are both at least 1.
8. The ionic liquid of claim 1 , wherein said anionic portion has the chemical formula:
wherein m is 0 or an integer of at least 1.
9. The ionic liquid of claim 8 , wherein m is a number from 0 to 11.
10. An olefin-paraffin separation membrane comprising a layer of the ionic liquid of claim 1 on an inert gas-permeable support.
11. The olefin-paraffin membrane of claim 10 , wherein said inert gas-permeable support comprises an alumina support.
12. A method for separating an olefin from a paraffin contained in a gaseous olefin-paraffin mixture, the method comprising passing said gaseous olefin-paraffin mixture through a layer of the ionic liquid of claim 1 .
13. The method of claim 12 , wherein the olefin in said gaseous olefin-paraffin mixture contains up to six carbon atoms, and the paraffin is a straight-chained, branched, or cyclic alkane containing up to six carbon atoms.
14. The method of claim 13 , wherein the olefin in said gaseous olefin-paraffin mixture contains at least three and up to six carbon atoms, and the paraffin is a straight-chained, branched, or cyclic alkane containing up to six carbon atoms.