STORAGE MEDIUM AND METHOD FOR SEPARATING, STORING AND TRANSPORTING CHLORINE FROM CHLORINE-CONTAINING GASES

Abstract

The invention relates to a storage medium and to a method for using a storage medium based on ionic compounds, which can reversibly absorb and store chlorine and chlorine from process gases, and which can release the same again by changing the ambient conditions, wherein the storage medium can be reused for this task after discharge.

Claims

1.-18. (canceled)

19. A storage medium serving as a chlorine store for the reversible absorption of chlorine from chlorine-containing gas, comprising at least one ionic compound of the general formula (I) and/or (II),
NR1.sub.mR2.sub.nR3.sub.o.sup.+Cl.sub.r.sup.(I)
PR4.sub.pR5.sub.q.sup.+Cl.sub.s.sup.(II) in which the radicals R1, R2, R3, R4, and R5 are independently identical or different alkyl radicals selected from the following group: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and 2-methylpropyl, wherein at least one radical R1, R2 or R3 is different from the respective other radicals R1, R2, and R3 and that the radicals R4 and R5 are different from one another, where m, n, o, p, and q are independently an integer in the series from 0 to 3 and where the sum m+n+o and the sum p+q must result in a value of 4, r and s are independently an odd number from 1 to 7, and where the storage medium is liquid within the working range of loading with chlorine and unloading of chlorine, at a temperature of 25 C. and a pressure of 1000100 hPa.

20. The storage medium as claimed in claim 19, wherein, in the compound of general formula (I), m and n are 1, 2, 3 and o is 0.

21. The storage medium as claimed in claim 19, wherein the ionic compound (I) or (II) is selected from at least one compound of the following series: NEtMe.sub.3Cl.sub.r, NEt.sub.2Me.sub.2Cl.sub.r, NEt.sub.3MeCl.sub.r, NBuEt.sub.2MeCl.sub.r, NMePr.sub.3Cl.sub.r, NBu.sub.2Me.sub.2Cl.sub.r, PEt.sub.3MeCl.sub.s, where r and s are independently an odd number from 1 to 7 and r and s are independently 1 or 3.

22. The storage medium as claimed in claim 19, wherein compound (I) is selected from at least one compound of the following series: NEtMe.sub.3Cl.sub.r, NEt.sub.2Me.sub.2Cl.sub.r, NEt.sub.3MeCl.sub.r, where r is a number 1 to 7 and r and s are 1 to 3.

23. A storage medium for the reversible absorption of chlorine from chlorine-containing gas, comprising at least one ionic compound of the formula (I) and/or of the formula (II) as claimed in claim 19, wherein the ionic compounds of the formula (I) and/or of the formula (II) contained therein are brought into contact with chlorine at ambient pressure (ambient atmospheric pressure, of 1 bar (1000 hPa) at sea level), and the ionic compounds react to form polychlorides of the formula (III) and/or of the formula (IV),
NR1.sub.mR2.sub.nR3.sub.o.sup.+Cl.sub.(r+2).sup.(III)
PR4.sub.pR5.sub.q.sup.+Cl.sub.(s+2).sup.(IV) where r and s are independently an odd number from 1 to 7.

24. The storage medium as claimed in claim 19, wherein the storage medium in the loaded state contains at least 0.65 g of Cl.sub.2 per g of ionic compound.

25. The storage medium as claimed in claim 19, wherein the storage medium in the loaded state is liquid at a temperature of 25 C. and a pressure of 1000 t 100 hPa.

26. The storage medium as claimed in claim 19, wherein the storage medium when fully loaded with chlorine has at a temperature of 25 C. and a pressure of 1000 hPa a dynamic viscosity of not more than 250 mPa.Math.s, and, independently thereof, the dynamic viscosity of the storage medium in the unloaded state is not more than 400 mPa.Math.s.

27. A process for removing chlorine from chlorine-containing gas, wherein the gas is contacted with a liquid storage medium comprising ionic compounds of the formula (I) and/or of the formula (II), with the chlorine contained in the gas bound in the form of ionic compounds of the formula (III) and/or of the formula (IV).
NR1.sub.mR2.sub.nR3.sub.o.sup.+Cl.sub.(r+2).sup.(III)
PR4.sub.pR5.sub.q.sup.+Cl.sub.(s+2).sup.(IV) in which the radicals R1, R2, R3, R4, and R5 are independently identical or different alkyl radicals selected from the following group: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and 2-methylpropyl, wherein at least one radical R1, R2 or R3 is different from the respective other radicals R1, R2, and R3 and that the radicals R4 and R5 are in each case different from one another, where in, n, o, p, and q are independently an integer in the series from 0 to 3 and where the sum m+n+o and the sum p+q must result in a value of 4, r and s are independently an odd number from 1 to 7 and r and s are independently 1 or 3.

28. The process as claimed in claim 27, wherein, in a first step as conditioning, the storage medium comprising compounds of the formula (I) and/or of the formula (II), where r and s=1, becomes loaded with chlorine gas only to such an extent that the storage medium liquefies.

29. The process as claimed in claim 28, wherein conditioning with chlorine takes place to such an extent that a storage medium of the formula (I) and/or of the formula (II) is obtained, where r and s are independently an odd number from 1 to 7 and r and s are independently 1 or 3, and where the storage medium is not fully loaded with chlorine.

30. The process as claimed in claim 28, wherein, in a second step after conditioning, chlorine is removed from chlorine-containing gas through contacting with the liquid storage medium from the first step, as a result of which the storage medium becomes loaded and the compounds of the formula (I) and/or of the formula (II) react to form ionic compounds of the formula (III) or (IV).

31. The process as claimed in claim 27, wherein the second step, the loading of the storage medium, takes place at a temperature in a range from 0 C. to 40 C., and a pressure within a range from 900 hPa to 7000 hPa.

32. A process for the reversible storage of chlorine from chlorine-containing gas in a storage medium, wherein, in a first step, a removal as claimed in claim 27 is executed and that, in a further process step, stored chlorine is removed from the loaded storage medium by increasing the temperature of the storage medium and/or lowering the partial pressure above the storage medium, with discharge of the chlorine obtained.

33. The process as claimed in claim 32, wherein the removal of chlorine through unloading of the reversible storage medium takes place at a temperature within a range from 40 C. to 200 C., and at a pressure within a range of 1000100 hPa.

34. The process as claimed in claim 32, wherein the removal of chlorine is initiated through reducing the partial pressure by at least 100 hPa compared to the first step.

35. The process as claimed in claim 32, wherein at least 0.10 g of chlorine per g of ionic compound, is released from the storage medium during this process.

36. A method comprising utilizing the storage medium as claimed in claim 19 for removing chlorine from chlorine-containing gases or as a reversible chlorine storage material for filling storage containers for chlorine.

Description

EXAMPLES

[0047] In order to obtain reversible storage media, ionic compounds that are solid at room temperature and ambient pressure (e.g. corresponding to the above formula I, where r and s=1) should first be fed into an initial loading with chlorine in order to bring about liquefaction of the ionic compound and associated formation of polychlorides. The liquefied polychlorides containing ionic compounds serve thereafter as reversible storage media and are only partially unloaded through the chosen release parameters, with the result that the storage media are liquid both in the loaded and in the unloaded state. In the case of ionic compounds or liquid mixtures of different ionic compounds to be used in the chlorine storage medium that are themselves liquid at room temperature, there is no need for preloading with chlorine to achieve the liquid state.

Example 1 (Prior Art)

[0048] A reactor was charged with tetrabutylammonium chloride [NBu.sub.4]Cl (100 g) and this was thermally equilibrated at 20 C. The initial loading of the ionic compound was effected by introducing chlorine at approx. 1000 hPa, which led to liquefaction of the [NBu.sub.4]Cl. This resulted in the absorption by the [NBu.sub.4]Cl of 61 g of chlorine, i.e. 0.61 g of chlorine per g of ionic compound. The loaded chlorine store was unloaded at 60 C., resulting in the release again of 23 g of chlorine, i.e. 0.23 g of chlorine per g of ionic compound. The dynamic viscosity of the unloaded chlorine store at 60 C. was 430 mPa.Math.s. The chlorine loads in the loaded and unloaded states were determined at 20 C. and 1000 hPa. The dynamic viscosity of the store in the chlorine-loaded and unloaded states was measured at 25 C. and 1000 hPa using a micro-Ubbelohde viscometer (inner diameter 0.53 mm, SI-Analytics GmbH, Mainz).

[0049] The combination of high viscosity and low chlorine release of the loaded chlorine store and the more difficult handling of the initially solid storage material has proved disadvantageous for implementation of the laboratory process on an industrial scale.

Example 2 (According to the Invention)

[0050] In order to obtain liquid and reversible storage media, a reactor was in a first step charged with solid triethylmethylammonium chloride [NEt.sub.3Me]Cl (100 g) and this was thermally equilibrated at 20 C. The initial loading of the ionic compound was effected by introducing chlorine at approx. 1000 hPa, as a result of which 87 g of chlorine was bound and the storage medium ([NEt.sub.3Me]Cl) liquefied. This resulted in the absorption by the [NEt.sub.3Me]Cl of 0.87 g of chlorine per g of ionic compound, the dynamic viscosity of the liquid, loaded chlorine store being 19 mPa.Math.s. Raman spectroscopy showed the loaded chlorine store to consist of a mixture of different tri- to nonachlorides, corresponding formally to [NEt.sub.3Me]Cl.sub.4.7. The loaded store was unloaded at 60 C., resulting in the release of 30 g of chlorine, i.e. 0.30 g of chlorine per g of ionic compound. The dynamic viscosity of the unloaded chlorine store was 44 mPa.Math.s.

[0051] Compared to chlorine stores based on [NBu.sub.4]Cl, the viscosity of the chlorine store in the loaded and unloaded state is substantially lower, while chlorine release is higher.

[0052] The liquid chlorine store could be unloaded at 60 C. to be loaded afresh with chlorine, with absorption carried out under the above-mentioned conditions (introduction of chlorine at approx. 1000 hPa and thermal equilibration of the reactor at 20 C.). In the renewed loading, 87 g of chlorine, i.e. 0.87 g of chlorine per g of ionic compound, was again absorbed and, during subsequent unloading under the above conditions (60 C.), 30 g of chlorine, i.e. 0.30 g of chlorine per g of ionic compound, was again released, with the storage medium always remaining liquid in the loaded and unloaded state. The liquid chlorine store could be loaded and unloaded more than 4 times without a decrease in the amounts of chlorine stored and released being observed.

Example 3 (According to the Invention)

[0053] In order to obtain liquid and reversible storage media, a reactor was in a first step charged with solid diethyldimethylammonium chloride [NEt.sub.2Me.sub.2]Cl (100 g) and this was thermally equilibrated at 20 C. The initial loading of the ionic compound was effected by introducing chlorine at approx. 1000 hPa, as a result of which 82 g of chlorine was bound and the storage medium ([NEt.sub.2Me.sub.2]Cl) liquefied. This resulted in the absorption by the [NEt.sub.2Me.sub.2]Cl of 0.82 g of chlorine per g of ionic compound, the dynamic viscosity of the liquid, loaded chlorine store being 16 mPa.Math.s. The loaded store corresponds formally to the composition [NEt.sub.2Me.sub.2]Cl.sub.4.2. The loaded store was unloaded at 60 C., resulting in the release again of 29 g of chlorine, i.e. 0.29 g of chlorine per g of ionic compound. The dynamic viscosity of the unloaded chlorine store was 37 mPa.Math.s.

[0054] Compared to chlorine stores based on [NBu.sub.4]Cl, the dynamic viscosity of the chlorine store in the loaded and unloaded state is substantially lower, while chlorine release is higher.

[0055] In analogous manner to example 2, the loaded liquid chlorine store could be loaded afresh with chlorine, with absorption carried out under the above-mentioned conditions (introduction of chlorine at approx. 1000 hPa and thermal equilibration of the reactor at 20 C.). In the renewed loading, 82 g of chlorine, i.e. 0.82 g of chlorine per g of ionic compound, was absorbed and, during subsequent unloading under the above conditions, 29 g of chlorine, i.e. 0.29 g of chlorine per g of ionic compound, was again released, with the storage medium always remaining liquid in the loaded and unloaded state. The liquid chlorine store could be loaded and unloaded more than 4 times without a decrease in the amounts of chlorine stored and released being observed.