Removing acetylene from ethylene gas streams during polyethylene synthesis
Disclosed herein are methods for removing acetylene from an ethylene gas stream wherein a catalyst reacts with the acetylene to polymerize said acetylene forming an ethylene gas stream substantially free of acetylene.
1. A method of removing acetylene from an ethylene gas stream comprising
contacting the gas stream with a catalyst such that the catalyst reacts with acetylene to polymerize the acetylene thereby forming an ethylene gas stream substantially free of acetylene;
wherein
the catalyst has a structure of
each R 1 is independently Ar 1 , C 1 -C 22 alkyl, or (R 3 ) 3 —Si—;
each R 2 is independently Ar 1 , C 3 -C 22 alkyl, or (R 3 ) 3 —Si—;
M is W or Mo;
Ar 1 is aryl or heteroaryl which can be optionally substituted, wherein the heteroaryl is a 5-12 membered aromatic ring comprising from 1 to 4 heteroatoms selected from O, N, and S, and the optional substitutions are 1 to 3 groups independently selected from halo, C 1-6 alkyl, OC 1-6 alkyl, and C 1-6 haloalkyl;
each occurrence of R 3 is independently C 1 -C 22 alkyl, Ar 1 , —O—(C 1 -C 22 alkyl), —O—Ar 1 , —N—(C 1 -C 22 ) 2 alkyl, or —N—Ar 1 2 ; and
L is absent or a neutral ligand.
2. The method of claim 1 , wherein each R 1 is C 1-22 alkyl.
3. The method of claim 2 , wherein at least one R 1 is t-butyl.
4. The method of claim 3 , wherein each R 1 is t-butyl.
5. The method of claim 1 , wherein at least one R 1 is Ar 1 .
6. The method of claim 5 , wherein at least one R 1 is phenyl.
7. The method of claim 1 , wherein each R 2 is C 1 -C 6 alkyl.
8. The method of claim 7 , wherein each R 2 is t-butyl.
9. The method of claim 1 , wherein L is absent.
10. The method of claim 1 , wherein L is a neutral ligand.
11. The method of claim 10 , wherein L is tetrahydrofuran, Et 2 O, thiophene, or pyridine.
12. The method of claim 11 , wherein L is tetrahydrofuran.
13. The method of claim 1 , wherein M is W.
14. The method of claim 1 , wherein the catalyst is in a solution.
15. The method of claim 14 , wherein the gas stream is bubbled through the solution.
16. The method of claim 1 , wherein the ethylene gas stream substantially free of acetylene comprises less than 1% by weight acetylene.
17. The method of claim 16 , wherein the ethylene gas stream substantially free of acetylene comprises less than 0.5% by weight acetylene.
18. The method of claim 1 , wherein the acetylene is polymerized at room temperature.
19. The method of claim 1 , wherein the acetylene is polymerized at atmospheric pressure.
20. The method of claim 1 , further comprising reacting the ethylene gas stream substantially free of acetylene under polymerization conditions to form polyethylene.