Method for producing a dehydrated liquid organic carbonate mixture
The present invention relates in a first aspect to a method for producing in the interior of a production equipment a dehydrated liquid mixture for use as a solvent for a conducting salt (e.g. LiPF 6 ) wherein after cleaning the equipment with isopropyl alcohol and providing or preparing a liquid starting mixture in said interior of the production equipment both the isopropyl alcohol content in the mixture and the water content in the mixture is reduced by interaction with a zeolite molecular sieve.
1. A method for producing in an interior of production equipment, a dehydrated liquid mixture, the method comprising:
a) cleaning the interior of the production equipment with isopropyl alcohol,
b) removing contaminating substances from the interior of the production equipment after step a so that the isopropyl alcohol content in the interior of the production equipment is reduced,
c) providing a liquid starting mixture in the interior of the production equipment after step (b), wherein the liquid starting mixture comprises:
a total amount of 90% by weight or more, based on the total amount of the liquid starting mixture, of at least one compound selected from the group consisting of an organic carbonate, an acetic acid ester of a C1 to C8 alcohol, and a butyric acid ester of a C1 to C8 alcohol, wherein the total amount of the acetic acid ester of the C1 to C8 alcohol and the butyric acid ester of the C1 to C8 alcohol ranges from 0% to 45% by weight, based on the total amount of the liquid starting mixture,
water in a total amount of 3500 ppm to 20 ppm, based on the total amount of the liquid starting mixture, and
isopropyl alcohol in a total amount of 100 ppm to 5 ppm, based on the total amount of the liquid starting mixture, and
d) contacting the liquid starting mixture provided in step c) with an amount of a zeolite molecular sieve such that both the isopropyl alcohol content and the water content in the mixture are reduced by interaction with the zeolite molecular sieve, thereby obtaining a dehydrated liquid mixture.
2. The method according to claim 1 , wherein said zeolite molecular sieve is a binderless zeolite molecular sieve or a binder-containing zeolite molecular sieve.
3. The method according to claim 1 , further comprising prior to step a):
(i) cleaning the interior of the production equipment with water and
(ii) reducing the water content in the interior of the production equipment.
4. The method according to claim 1 , wherein cleaning in step a) is carried out by flushing or rinsing the interior of the production equipment.
5. The method according to claim 1 , wherein the contaminating substances comprise one or more compounds selected from the group consisting of water, an alcohol, toluene and acetone.
6. The method according to claim 1 , wherein step b) comprises removing the contaminating substances from the interior of the production equipment by vacuum evaporation at a pressure ranging from 0.01 mbar to 850 mbar.
7. The method according to claim 1 , wherein step b) comprises purging the interior of the production equipment with a purge gas.
8. The method according to claim 1 , wherein the total amount of water in the liquid starting mixture ranges from 3000 ppm to 20 ppm.
9. The method according to claim 1 , wherein in step d) the water content in the mixture is reduced to less than 20 ppm, based on a total amount of the dehydrated liquid mixture.
10. The method according to claim 1 , wherein the at least one compound in the liquid starting mixture is the organic carbonate of Formula (I)
wherein R1 and R2 independently are an alkyl group of one or more carbon atoms,
or
R1 and R2 together form a substituted or unsubstituted alkylene bridge linking the oxygen atoms.
11. The method according to claim 1 , wherein the liquid starting mixture in the interior of the production equipment comprises
isopropyl alcohol in a total amount of 100 ppm to 25 ppm, and
wherein in step d) the isopropyl alcohol content in the mixture is less than 25 ppm, based on the total amount of the dehydrated liquid mixture.
12. The method according to claim 1 , wherein the zeolite molecular sieve comprises a shaped body.
13. The method according to claim 1 , wherein the zeolite molecular sieve is a packed bed loaded with the zeolite molecular sieve.
14. The method according to claim 1 , wherein the concentration of sodium ion, potassium ion, silicon ion, aluminum ion or calcium ion are all 5 ppm or less, based on a total amount of the dehydrated liquid mixture.
15. The method according to claim 1 , wherein the total amount of water in the liquid starting mixture ranges from 2000 ppm to 20 ppm, based on the total amount of the liquid starting mixture.
16. The method according to claim 1 , wherein the total amount of water in the liquid starting mixture ranges from 1000 ppm to 20 ppm, based on the total amount of the liquid starting mixture.
17. The method according to claim 1 , wherein the total amount of water in the liquid starting mixture ranges 500 ppm to 20 ppm, based on the total amount of the liquid starting mixture.
18. The method according to claim 1 , wherein the total amount of water in the liquid starting mixture ranges from 400 ppm to 20 ppm, based on the total amount of the liquid starting mixture.
19. The method according to claim 1 , wherein the total amount of water in the liquid starting mixture ranges from 300 ppm to 20 ppm, based on the total amount of the liquid starting mixture.
20. The method according to claim 1 , wherein the total amount of water in the liquid starting mixture ranges from 200 ppm to 20 ppm, based on the total amount of the liquid starting mixture.
21. The method according to claim 1 , wherein the total amount of water in the liquid starting mixture ranges from 150 ppm to 20 ppm, based on the total amount of the liquid starting mixture.