Method for producing a dehydrated liquid organic carbonate mixture

Abstract

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.sub.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.

Claims

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) ##STR00014## 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.

Description

(1) The first aspect of the present invention (method for producing a dehydrated liquid mixture) is additionally described below by reference to the appended FIGS. 1 to 3:

(2) FIG. 1 shows an illustrative flow diagram illustrating the method according to the present invention for producing a dehydrated liquid mixture in the interior of the production equipment for use as a solvent for a conducting salt.

(3) FIG. 2 shows a more detailed flow diagram illustrating the method according to the present invention.

(4) FIG. 3 shows an even more detailed flow diagram illustrating the method according to the present invention.

(5) FIG. 4 diagrammatically shows a production unit for producing an electrolyte mixture, according to the second aspect of the present invention (method for producing an electrolyte mixture).

(6) FIG. 1 shows an illustrative flow diagram 10 of the method according to the present invention. In flow diagram 10 four different basic steps (steps 11 to 14) are depicted.

(7) As a first basic step 11 a cleaning step a) is conducted (i.e. cleaning of the interior of the production equipment with isopropyl alcohol). After said first basic step 11 a second basic to step 12 is conducted which represents removing step b) of the method of the present invention, wherein the contaminating substances are removed from the interior of the production equipment after said cleaning with isopropyl alcohol, so that the isopropyl alcohol content in the interior of the production equipment is reduced. After said second basic step 12 a third basic step 13 is conducted which represents step c) of the method of the present invention (i.e. providing or preparing a liquid starting mixture in said interior of the production equipment after said removal of contaminating substances, wherein the liquid starting mixture in said interior of the production equipment comprises a total amount of 90% by weight or more, based on the total amount of the liquid starting mixture, of compounds selected from the group of organic carbonates, acetic acid esters of C1 to C8 alcohols and butyric acid esters of C1 to C8 alcohols, wherein the total amount of acetic acid esters of C1 to C8 alcohols and butyric acid esters of C1 to C8 alcohols is in the range of 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, isopropyl alcohol in a total amount of 100 ppm to 5 ppm, based on the total amount of the liquid starting mixture, optionally further compounds).

(8) After said basic step 13 a fourth basic step 14 is conducted which represents contacting step d) of the method of the present invention (i.e. contacting the liquid starting mixture resulting after step c) with an amount of a zeolite molecular sieve such that both the isopropyl alcohol content in the mixture and the water content in the mixture is reduced by interaction with said zeolite molecular sieve).

(9) FIG. 2 shows a more detailed flow diagram 20 illustrating the method according to the present invention and referring to the four basic steps 11 to 14 depicted in FIG. 1. In addition, compounds and mixtures 24, 25, 25.1, 25.2, 26.1, 26.2, 27 and 28 as well as a material 29.1 and a material 29.2 and the individual steps 12.1, 12.2, 13.1 and 13.2 are depicted. In FIG. 2 method steps are depicted in transparent boxes whereas a compound (also a mixture) and a material are depicted in boxes having different diagonal lines.

(10) Prior to basic step 11, isopropyl alcohol 24 is introduced into the interior of the production equipment. In basic step 11 said interior is cleaned by contacting the inner surfaces of the interior of the production equipment with isopropyl alcohol, preferably by rinsing or flushing said inner surfaces with isopropyl alcohol (in some cases while the inner surfaces of the interior of the production equipment are heated). After basic step 11 is conducted the resulting contaminating substances 25 (which are or mostly comprise isopropyl alcohol) are removed from the interior of the production equipment in basic step 12. This removal in basic step 12 typically comprises consecutive individual steps. A first individual step 12.1 is conducted including one or more than one steps selected from the group of steps consisting of (actively) pumping or sucking out said contaminating substances and (passively) allow for running off (draining) said contaminating substances in order to remove the major volume 25.1 of the contaminating substances. After individual step 12.1, a second individual step 12.2 is carried out in order to remove remaining amounts 25.2 of contaminating substances, wherein individual step 12.2 comprises one or more steps selected from the group of steps consisting of vacuum evaporation at a pressure in the range of from 0.01 mbar to 850 mbar (preferably in the range of from 0.1 mbar to 500 mbar, more preferably in the range of from 1 mbar to 100 mbar) and purging the interior of the production equipment with a purge gas, preferably nitrogen gas, wherein preferably the nitrogen gas has a temperature in the range of from 273.15 Kelvin to 473.15 Kelvin (more preferably in the range of from 293.15 Kelvin to 373.15 Kelvin). Alternatively, dry air can be used instead of nitrogen gas, preferably at a temperature in the range of from 273.15 Kelvin to 473.15 Kelvin. After basic step 12, almost no contaminating substances are present in the interior of the production equipment and basic step 13 is conducted, either by means of alternative step 13.1 (left hand arrow) or alternative step 13.2 (right hand arrow).

(11) According to alternative step 13.1 the major compounds 26.1 of the liquid starting mixture (i.e. organic carbonates, optional acetic acid esters of C1 to C8 alcohols, optional butyric acid esters of C1 to C8 alcohols, and optional further compounds; typically accompanied by trace amounts of water) are provided as a pre-starting mixture 26.2 (typically also including trace amounts of water), wherein this pre-starting mixture 26.2 is introduced into the interior of the production equipment, thus providing a liquid starting mixture 27 in the interior of the production equipment.

(12) According to alternative step 13.2 the major compounds 26.1 of the liquid starting mixture are mixed with each other within the interior of the production equipment such that the liquid starting mixture 27 results in the interior of the production equipment, thus preparing a liquid starting mixture in the interior of the production equipment.

(13) The result of basic step 13 is a liquid starting mixture 27 which comprises a total amount of 90% by weight or more, based on the total amount of the liquid starting mixture, of compounds selected from the group of organic carbonates, acetic acid esters of C1 to C8 alcohols and butyric acid esters of C1 to C8 alcohols, wherein the total amount of acetic acid esters of C1 to C8 alcohols and butyric acid esters of C1 to C8 alcohols is in the range of 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, isopropyl alcohol in a total amount of 100 ppm to 5 ppm, based on the total amount of the liquid starting mixture, optionally further compounds.

(14) Thus, liquid starting mixture 27 is a result after the (mixed) major compounds 26.1 of the liquid starting mixture were in contact with the inner surfaces of the interior of the production equipment.

(15) After basic step 13, basic step 14 is conducted, i.e. the liquid starting mixture 27 being the result of basic step 13 is contacted with an amount of a zeolite molecular sieve 29.1 such that both the isopropyl alcohol content in the mixture and the water content in the mixture is reduced by interaction with said zeolite molecular sieve. In FIG. 2 the same zeolite molecular sieve is depicted in two different states (29.1 and 29.2): the zeolite molecular sieve material 29.1 represents the sieve material prior to the interaction with the liquid starting mixture 27, whereas the zeolite molecular sieve material 29.2 depicts the state after the zeolite molecular sieve material has interacted with the liquid starting mixture 27 in order to produce a dehydrated liquid mixture 28. This means that the zeolite molecular sieve material 29.1 represents a material providing a higher loading capacity for water molecules and isopropyl alcohol molecules compared to the loading capacity of the zeolite molecular sieve material 29.2, representing a material which is loaded with water molecules and isopropyl alcohol molecules through interaction with the liquid starting mixture 27. The result of basic step 14 is (i.e. as a result of said interaction) the dehydrated liquid mixture 28, which has a reduced water content (preferably providing a water content of less than 20 ppm, based on the total amount of the dehydrated liquid mixture) and a reduced isopropyl alcohol content (preferably the isopropyl alcohol content is less than 25 ppm, more preferably less than 5 ppm, based on the total amount of the dehydrated liquid mixture).

(16) FIG. 3 shows an even more detailed flow diagram 30 illustrating the method according to the present invention. The flow diagram in FIG. 3 is identical with the flow diagram shown in FIG. 2 with the only difference that in flow diagram 30 the additional steps 31 and 35 are depicted as well as an additional compound 32 and an additional mixture 36.

(17) Prior to additional step 31, (chemically clean) water 32 is introduced into the interior of the production equipment. In step 31 said interior is cleaned by contacting the inner surfaces of the interior of the production equipment, preferably by rinsing or flushing said inner surfaces with the water (a boiling out with water is less preferred). After cleaning step 31 is conducted, the resulting water 36 (which is or mostly comprises water) is removed from the interior of the production equipment in removing step 35. This removal comprises one or more than one further individual steps selected from the group of steps consisting of (actively) pumping or sucking out said resulting water, (passively) allow for running off (draining) said resulting water, vacuum evaporation at a pressure in the range of from 0.01 mbar to 850 mbar (preferably in the range of from 0.1 mbar to 500 mbar, more preferably in the range of from 1 mbar to 100 mbar) and purging the interior of the production equipment with a purge gas, preferably nitrogen gas, wherein preferably the nitrogen gas has a temperature in the range of from 273.15 Kelvin to 473.15 Kelvin (preferably in the range of from 293.15 Kelvin to 373.15 Kelvin). After removing step 35 the method continues as described above with reference to FIG. 2.

(18) FIG. 4 diagrammatically shows a production unit for producing an electrolyte mixture, comprising a feed line 100 connected with a first mixing unit 120. The first mixing unit 120 comprises a first agitator 125 for a first mixing process. The first mixing unit 120 is connected by means of duct 121 with a dehydration unit 130 comprising a packed bed of a dehydration column loaded with shaped bodies of zeolite molecular sieve material. The outlet side of the dehydration unit 130 is connected by means of duct 131 with a second mixing unit 170, connected to a feed line 173 (for providing a feed of one or more conducting salts and optionally additional ingredients) and comprising a second agitator 175 for a second mixing process. The outlet of the second mixing unit 170 is connected with a to filter unit 180 by means of duct 171. Connected with the outlet side of the filter unit 180 is an effluent duct 181 for product withdrawal.

(19) A nitrogen feed line 191 is connected with the first and second mixing unit 120 and 170, respectively, via two individual transfer ducts 193 and 195, respectively, in order to ventilate said mixing units with nitrogen gas while the mixing units are filled or emptied.

(20) For conducting a method according to the second aspect of the present invention the interior of the production equipment as described with reference to FIG. 4 is cleaned as described in the method of the present invention (according to the first aspect). This means that after all cleaning steps the liquid starting mixture is either filled into or produced (preferably produced) in the first mixing unit 120 by means of feed line 100. With mixing by first agitator 125 the compounds of the liquid starting mixture are mixed in the first mixing unit 120 (in particular in order to produce the liquid starting mixture according to step c). The resulting liquid starting mixture is transferred by means of duct 121 into dehydration unit 130. In the dehydration unit 130 the liquid starting mixture is contacted with the zeolite molecular sieve material such that the water content and the isopropyl alcohol content in said liquid starting mixture is reduced, preferably the water content is reduced to an amount of less than 20 ppm, and, preferably, the isopropyl alcohol content is reduced to an amount of less than 25 ppm, more preferably to less than 5 ppm. After the reduction of the water and isopropyl alcohol content in dehydration unit 130 a dehydrated liquid mixture is produced. The dehydrated liquid mixture is transferred into the second mixing unit 170 by means of duct 131. Into the second mixing unit 170 additionally one or more conducting salts and optionally additional ingredients are added by means of feed line 173 and mixed with the dehydrated liquid mixture by second agitator 175 to produce an electrolyte mixture. The electrolyte mixture produced in the second mixing unit 170 is transported to the filter unit 180 by means of duct 171. After filtration of the electrolyte mixture in filter unit 180 (in order to remove abrasion products of the zeolite molecular sieve material and other dust particles from the raw materials and/or from the dehydration process) the filtered electrolyte mixture is withdrawn from the process by the effluent duct 181.

(21) The present invention is furthermore described below in more detail by reference to Examples.

EXAMPLES

(22) 1. Sample Preparation

(23) An experimental liquid starting mixture (experimental mixture I) consisting of dimethyl carbonate, H.sub.2O (229 ppm, based on the total amount of the experimental liquid starting to mixture) and isopropyl alcohol (60 ppm, based on the total amount of the experimental liquid starting mixture), was prepared. Thus, experimental mixture I comprises one organic carbonate in a total amount of 90% by weight or more, based on the total amount of the liquid starting mixture.

(24) Experimental mixture I was subsequently split into 6 portions each providing 50 ml resulting in 6 experimental sample mixtures (S1 to S6).

(25) 2. Sample Treatment

(26) Experimental sample mixtures S1 and S2 were treated with a zeolite molecular sieve of Linde Typ 13X, whereas experimental sample mixtures S3 and S4 were treated with binderless zeolite molecular sieves of Linde Typ 4A, experimental sample mixtures S5 and S6 with binder-containing zeolite molecular sieves of Linde Typ 4A, respectively. Prior to treatment, each experimental sample mixture and a weighed amount of zeolite molecular sieve material was filled and mixed in respective flasks (made of glass) which were shaken in a shaking cabinet during one night for 20 hours at 25 C. Each respective zeolite molecular sieve material was predried at 200 C. in a vacuum oven (10 mbar) overnight prior to usage. The shaking cabinet was purged with nitrogen during each experiment and each flask had a glued septum in its cap.

(27) For the determination of the water content, a sample of the supernatant was taken with a syringe through the septum of each flask. Analysis was carried out by coulometric Karl-Fischer titration. The amount of isopropyl alcohol was determined by Headspace gas chromatography. Prior to use, syringes were predried in a desiccator for at least 48 h.

(28) The compositions of each experimental sample mixture S1 to S6 is shown in Table 1. The following abbreviations are used:

(29) DMC: dimethyl carbonate

(30) MS 13X: zeolite molecular sieve 13X

(31) MS 4A BF: binderless zeolite molecular sieve 4A

(32) MS 4A: binder-containing zeolite molecular sieve 4A

(33) TABLE-US-00005 TABLE 1 S1 S2 S3 S4 S5 S6 DMC [ml] 50 50 50 50 50 50 MS 13X [g] 2.034 5.053 MS 4A BF [g] 2.077 5.039 MS 4A [g] 2.023 5.053

(34) 3. Treatment Results

(35) Table 2 shows the amount of water and the amount of isopropyl alcohol after 20 hours of sample treatment.

(36) TABLE-US-00006 TABLE 2 S1 S2 S3 S4 S5 S6 H.sub.2O [ppm] 17.7 17.8 3.6 2.3 3.8 3.9 isopropyl 50 40 30 <5 15 <5 alcohol [ppm]

(37) The water content after 20 hours of sample treatment was determined twice for each sample. In Table 2 the average values are shown.

(38) As shown in Table 2 in each sample S1 to S6 the water content was reduced compared to the water content in each respective sample prior to the treatment. In each sample the water content was reduced even to an amount below 20 ppm, based on the total amount of each respective experimental sample mixture. In addition, the amount of isopropyl alcohol was simultaneously reduced in each sample (also compared to each respective to sample prior to the treatment). In samples S4, S5 and S6 the amount of isopropyl alcohol was even reduced to an amount of less than 25 ppm, based on the total amount of each respective experimental sample mixture.