Method for storing chlorine in a chlorine storage medium, storing chlorine from a chlorine storage medium and separating chlorine
By using a chlorine storage medium composed of organic salts and organic solvents, the problem of inconvenient chlorine storage in existing technologies has been solved, achieving efficient and safe chlorine storage and transportation, and releasing chlorine with high purity and controllability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU FUXING POWER CO LTD
- Filing Date
- 2024-12-09
- Publication Date
- 2026-06-09
Smart Images
Figure CN122166719A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of chlorine storage, and more particularly to a chlorine storage medium, a method for storing chlorine in the chlorine storage medium, and a method for separating chlorine. Background Technology
[0002] In the industrial production and use of chlorine, chlorine gas typically needs to be liquefied to purify, recover, and transport it. In chlorine production, liquefaction is used to separate impurity gases, such as oxygen, nitrogen, or carbon dioxide, from the chlorine gas. These gases have lower boiling points than chlorine and can therefore be separated as gaseous phases through chlorine liquefaction. In industrial applications, chlorine gas generally needs to be liquefied before being transported via pipelines or roads. The liquefaction of chlorine gas at high pressures of 7 bar or extremely low temperatures of around -35°C results in significant energy consumption and high costs.
[0003] To withstand high pressure, the walls of compressed gas cylinders and pipelines used for storing and transporting chlorine are typically very thick, making them heavy and increasing production and transportation costs. Furthermore, the transportation of cylinders and the release of chlorine must be carried out under special safety precautions. Simultaneously, chlorine in the compressed cylinders must be released through a cylinder pressure regulator, which must be tightly sealed to the cylinder and equipment to prevent chlorine escape and potential hazards.
[0004] There is a need to find a chlorine storage medium that can absorb and store large quantities of chlorine under mild conditions and release the chlorine as needed, in order to avoid the energy-intensive liquefaction of chlorine under low temperature and / or high pressure.
[0005] By ensuring sufficient contact between the chlorine storage medium and chlorine gas, the medium will absorb the chlorine gas using its chemical or physical properties. When the storage medium ceases to absorb further chlorine gas, it is considered to be in a loaded state. The absorbed chlorine gas in the storage medium can be released by altering environmental conditions (increasing temperature, decreasing partial pressure, gas purging, etc.). When the storage medium ceases to release further chlorine gas, it is considered to be in an unloaded state.
[0006] Existing technologies disclose chlorine storage media based on physical adsorption for chlorine absorption. However, the chlorine loading (chlorine stored per gram of material) of such storage materials is very low because there is only a physical interaction between the porous solid and the chlorine. For example, US5376164A1 discloses the adsorption of chlorine on various zeolites and silica gels, with a loading of less than 0.2 g of chlorine observed per gram of storage material under the measured conditions (room temperature, 0.87 bar).
[0007] Ionic compounds composed of certain organic cations and chlorides have a high affinity for chlorine gas and can bind chlorine in the form of polychlorinated ions. WO2007109611A1 discloses a medium for the safe storage and transportation of chlorine gas under ambient pressure, preferably 1-methyl-3-ethylimidazolium chloride and pyridinium hydrochloride. However, this medium is solid at room temperature, which limits its application in filling and transportation.
[0008] WO12130803A1 discloses a method for separating chlorine from a mixture (CO, CO2, N2, methyl isocyanate, and methyl bromide), preferably trihexytetradecylphosphonium chloride, 1-benzyl-3-methylimidazolium chloride, and 1-methyl-3-octylimidazolium chloride. However, the reversible liquid chlorine storage medium based on trihexytetradecylphosphonium chloride is very viscous under load (η>407 mPa·s at 25°C), which is not conducive to large-scale applications.
[0009] EP18170956.9 discloses a method based on the general formula N-R1 m R2 n R3 o + Cl r - Or P-R4 p R5 q + Cl s - Ionic compounds are used as reversible chlorine storage media, with R1 and other groups selected from alkyl groups with 5 or fewer carbon atoms. However, the preferred trimethylethylammonium chloride, dimethyldiethylammonium chloride, and methyltriethylammonium chloride are all solids at room temperature, which limits their flexibility in filling and transportation.
[0010] EP3805150B1 also uses the general formula N-R1 m R2 n R3 o + Cl r - Or P-R4 p R5 q + Cl s - The method involves the absorption of chlorine by ionic compounds. Its key feature is the controlled release of chlorine gas from the storage medium by adding a protonated liquid release agent, preferably water or an aqueous solution of an inorganic acid. However, this method requires separation of the release agent after chlorine release, which hinders the reuse of the storage medium. Furthermore, the addition of water inevitably leads to the generation of water vapor, reducing the purity of the chlorine gas.
[0011] The current technical problem is that existing chlorine storage media are solid or high-viscosity liquids at room temperature, which is inconvenient for absorbing chlorine and filling and transporting it; adding a release agent can release chlorine in a controlled manner, but this will result in low purity of chlorine and the release agent needs to be separated for repeated use.
[0012] Therefore, it is indeed necessary to provide an improved chlorine storage medium to overcome the problems existing in the current chlorine storage medium. Summary of the Invention
[0013] The present invention provides a chlorine storage medium, which is a mixture of at least one organic salt and an organic solvent, wherein the organic salt is selected from one or more of tetraalkylphosphonium and tetraalkylammonium, and the organic solvent is selected from one or more of bromobenzene, propylene glycol phenyl ether, 4-chlorodiphenyl ether, 3,4-dichlorodiphenyl ether, pyridine, 2-chloropyridine, and 2,4-dichloropyridine. The chlorine storage medium is liquid at a temperature of 25°C and a pressure of 1000±100 hPa.
[0014] Quaternary ammonium cations and quaternary phosphate cations have a strong attraction to chloride anions, which can combine with them to form monochloride salts or even polychloride salts, thus making them suitable for storing chlorine. However, tetraalkylammonium / phosphate salts, which can combine with chlorine to form ionic compounds, are usually solids or high-viscosity liquids, making them unsuitable for use in chlorine storage media. Organic solvents can effectively dissolve tetraalkylammonium / phosphate salts into organic ions, allowing them to fully contact with chlorine in the liquid phase and form polychloride ion compounds. Organic ions and chloride ions can be uniformly distributed in the solution with low steric hindrance, which is conducive to the formation of high chloride number ion salts and increases the chlorine storage capacity of the storage medium. Chlorine exists in the solvent in both molecular and ionic forms, and can interconvert at any time, which is conducive to the rapid replenishment of chloride ions after consumption. Therefore, the chlorine storage rate of this storage medium is relatively fast. At the same time, due to the dissolution and absorption of chlorine by the solvent, the chlorine storage capacity of this storage medium is not low even if the content of organic salts is not high.
[0015] In one embodiment, the organic salt is selected from one or more of trimethylethylammonium chloride, dimethyldiethylammonium chloride, methyltriethylammonium chloride, methyldiethylbutylammonium chloride, tripropylmethylammonium chloride, dibutyldimethylammonium chloride, and triethylmethylphosphoric acid. This ammonium / phosphorus salt exhibits high solubility in organic solvents, rapidly dissolving into tetraalkylammonium ions and chloride ions. Furthermore, its groups are all straight-chain alkyl groups with minimal steric hindrance, facilitating the rapid attack of chlorine ions on ammonium / phosphorus ions in the solvent, thereby storing chlorine gas as a polychlorinated compound and effectively reducing the saturated vapor pressure of chlorine.
[0016] In one embodiment, the organic salt is selected from one or more of trimethylethylammonium chloride, dimethyldiethylammonium chloride, and methyltriethylammonium chloride. A comparison of Examples 1-4 shows that tetraalkylammonium chloride, with its lower carbon number, has a higher chlorine storage capacity per unit mass of ionic salt due to its lower molecular weight, making it more advantageous for chlorine storage. Examples 3 and 5 demonstrate that ammonium cations are more conducive to binding chloride ions than phosphorus cations.
[0017] In one embodiment, the organic solvent is selected from 3,4-dichlorodiphenyl ether and 2,4-dichloropyridine. These dichloro-substituted organic solvents not only have relatively high chlorine solubility, but also have their highly reactive sites replaced by chloride ions. This avoids chlorine from undergoing a substitution reaction by attacking the carbocation group via nucleophilic reactions, thus preventing chlorine from being wasted in the reaction with the solvent. It also avoids the generation of HCl, which would reduce the purity of the chlorine.
[0018] In one embodiment, chlorine is released by heating a chlorine-loaded chlorine storage medium. The polychlorinated compounds in the storage medium are unstable; heating intensifies their molecular thermal motion, causing chloride ions to recombine into chlorine molecules that escape. The inorganic salts and organic solvents used in this chlorine storage medium have extremely low saturated vapor pressures at 60°C and are stable, thus preventing the release of other gases and ensuring the purity of the chlorine.
[0019] In one embodiment, chlorine is released by depressurizing a chlorine-loaded storage medium. The polychloride compounds in the storage medium exist in ionic form, and a dynamic equilibrium exists between various ions and molecules in the solvent. After depressurization, the solubility of chlorine in the solvent decreases, chloride ions recombine to form chlorine molecules and escape, and as the amount of chlorine in the solvent decreases, the polychloride compounds tend to decompose into monochloride salts and chloride ions. The inorganic salts and organic solvents used in this chlorine storage medium have extremely low saturated vapor pressures at room temperature and are stable, thus preventing the release of other gases and ensuring the purity of the chlorine.
[0020] In one embodiment, chlorine is released by purging a chlorine-loaded chlorine storage medium with a purge gas. The purge gas, referred to as the carrier gas, contains no chlorine or contains very little chlorine, causing the chlorine to transfer from the liquid phase to the gas phase, thereby carrying the chlorine out of the chlorine storage medium. The carrier gas is selected from air, nitrogen, carbon dioxide, water vapor, etc., preferably an inert gas. In one embodiment, the chlorine-loaded chlorine storage medium is sprayed down from the top of a desorption tower, and the carrier gas comes into countercurrent contact with the chlorine storage medium from the bottom up of the desorption tower, releasing the chlorine. In another embodiment, inert nitrogen gas is introduced into the chlorine-loaded chlorine storage medium, and the mixed gas above the chlorine storage medium is collected through an exhaust pipe and transported to a reactor. The controlled release of chlorine can be achieved by controlling the flow rate of the nitrogen gas.
[0021] In one embodiment, another subject of the invention is a method for using the novel chlorine storage medium to store chlorine gas, particularly for filling chlorine gas storage containers. Storage containers include pressure tanks, gas cylinders, and safety containers for corrosive liquids.
[0022] The aforementioned chlorine storage medium can be used to separate chlorine from chlorine-containing process gases, particularly from process gases containing H2, CO2, O2, CO, NO, NO2, N2O4, SO2, SO3, SO, S2O2, SO4, and mixtures thereof. Chlorine can be separated from the gas mixture by ensuring sufficient contact between the chlorine-containing process gas and the storage medium. The contact between the storage medium and the chlorine-containing gas can, in principle, be carried out in any known gas-liquid absorption device, such as a packed tower or plate tower. After chlorine absorption, the storage medium accumulates at the bottom of the container and can continue to absorb or be discharged in liquid form. The chlorine-free gas, after separation, accumulates in the upper gas phase and can be easily separated.
[0023] The beneficial effects of this invention are as follows: This chlorine storage medium is a low-viscosity liquid under working conditions, resulting in a high chlorine storage rate and a large chlorine storage density per unit mass. It is also advantageous for use in liquid filling and pipeline transportation. This chlorine storage medium effectively reduces the saturated vapor pressure of chlorine at room temperature. In the event of accidental leakage, the release rate of chlorine in the storage medium is very low, effectively reducing the risk to environmental safety. Therefore, this chlorine storage medium is an ideal medium for transporting toxic, highly volatile, and corrosive chlorine. Furthermore, chlorine can be released and utilized in a controlled manner by heating the chlorine-loaded storage medium, reducing its partial pressure, or purging with gas. The vapor pressure of this chlorine storage medium is very low, preventing it from entering the gas phase, thus resulting in high purity released chlorine.
[0024] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below.
[0025] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description
[0026] Figure 1 This is a graph showing the relationship between different mass concentrations of chlorine gas in the chlorine storage medium and system pressure (psi). Detailed Implementation Example 1
[0027] Solid triethylmethylammonium chloride [NEt3Me]Cl (33.3 g) and 2,4-dichloropyridine (66.7 g) were added to the reactor at 20 °C and dissolved to form a solution. Small amounts of chlorine gas were gradually added, and the total system pressure was continuously monitored. The relationship between system pressure and chlorine weight percentage is as follows: Figure 1 As shown, ▲ represents the experimental point, and ■ represents the vapor pressure of pure chlorine. (From...) Figure 1 It is known that this chlorine storage medium can store 46% chlorine gas by weight, meaning that 100 grams of the storage medium can bind 84 grams of chlorine gas, while maintaining a saturated vapor pressure below 1000 hPa. The dynamic viscosity of this chlorine storage medium after loading was measured to be 9 mPa·s at 25°C and 1000 hPa using a micro-Ubbelohde viscometer. Raman spectroscopy reveals that the loaded chlorine storage medium consists of a mixture of different trichlorides to nonachlorides, and its form corresponds to [NEt3Me]Cl. 3.5.7.9 The loaded chlorine storage medium was unloaded at 1000 hPa and 60°C, releasing 38 grams of chlorine gas, which is 0.38 grams of chlorine gas per gram of storage medium. The dynamic viscosity of the chlorine storage medium after unloading at 20°C was 15 mPa·s.
[0028] The unloaded liquid chlorine storage medium can be reloaded with chlorine gas, that is, it reabsorbs 38 grams of chlorine gas at 1000 hPa and 20°C, and unloads at 60°C, releasing 37 grams of chlorine gas. This chlorine storage medium can be loaded and unloaded more than four times without a significant decrease in the amount of stored and released chlorine gas, indicating that the sample is stable and reusable. Example 2
[0029] Solid triethylmethylammonium chloride [NEt3Me]Cl (33.3 g) and 3,4-dichlorodiphenyl ether (66.7 g) were added to the reactor at 20°C and dissolved into a solution. Chlorine gas was allowed to fully contact the storage medium at approximately 1000 hPa to complete the initial loading of the storage medium, resulting in the binding of 71 g of chlorine gas. Therefore, the absorption capacity of this storage medium is 0.71 g chlorine gas / g storage medium, and the dynamic viscosity after loading is 11 mPa·s. The loaded storage medium was unloaded at 1000 hPa and 60°C, releasing 32 g of chlorine gas, i.e., a release capacity of 0.32 g chlorine gas / g storage medium. The dynamic viscosity of the unloaded storage medium at 20°C is 22 mPa·s. This storage medium can be loaded and unloaded more than 4 times without a significant decrease in the amount of stored and released chlorine gas. Example 3
[0030] Solid trimethylethylammonium chloride [NEtMe3]Cl (33.3 g) and 2,4-dichloropyridine (66.7 g) were added to the reactor at 20°C and dissolved into a solution. Chlorine gas was allowed to fully contact the storage medium at 1000 hPa to complete the initial loading of the storage medium, resulting in the binding of 62 g of chlorine gas. Therefore, the absorption capacity of this storage medium is 0.62 g of chlorine gas / g of storage medium, and the dynamic viscosity after loading is 10 mPa·s. The loaded storage medium was unloaded at 1000 hPa and 60°C, releasing 36 g of chlorine gas, i.e., a release of 0.36 g of chlorine gas / g of storage medium. The dynamic viscosity of the unloaded storage medium at 20°C is 16 mPa·s. This storage medium can be loaded and unloaded more than 4 times without a significant decrease in the amount of stored and released chlorine gas. Example 4
[0031] Solid methyltripropylammonium chloride [NEtPr3]Cl (33.3 g) and 3,4-dichlorodiphenyl ether (66.7 g) were added to the reactor at 20°C and dissolved into a solution. Chlorine gas was allowed to fully contact the storage medium at 1000 hPa to complete the initial loading of the storage medium, resulting in the binding of a total of 73 g of chlorine gas. Therefore, the absorption capacity of this storage medium is 0.73 g / g of storage medium, and the dynamic viscosity after loading is 13 Pa·s. The storage medium was unloaded at 1000 hPa and 60°C, releasing 21 g of chlorine gas, i.e., a release of 0.21 g of chlorine gas / g of storage medium. The dynamic viscosity of the unloaded storage medium at 20°C is 24 mPa·s. This storage medium can be loaded and unloaded more than 4 times without a significant decrease in the amount of stored and released chlorine gas. Example 5
[0032] Solid triethylmethylphosphorus chloride [PEtMe3]Cl (33.3 g) and 2,4-dichloropyridine (66.7 g) were added to the reactor at 20 °C and dissolved into a solution. Chlorine gas was allowed to fully contact the storage medium at 1000 hPa to complete the initial loading of the storage medium, resulting in the binding of 54 g of chlorine gas. Therefore, the absorption capacity of this storage medium is 0.54 g / g of storage medium, and the dynamic viscosity after loading is 7 Pa·s. The loaded storage medium was unloaded at 1000 hPa and 60 °C, releasing 25 g of chlorine gas, i.e., a release of 0.25 g of chlorine gas / g of storage medium. The dynamic viscosity of the unloaded storage medium at 20 °C is 19 mPa·s. This storage medium can be loaded and unloaded more than 4 times without a significant decrease in the amount of stored and released chlorine gas.
[0033] Comparative Example 1 Solid triethylmethylammonium chloride [NEt3Me]Cl (100 g) was loaded into a reactor at 20 °C. Chlorine gas was introduced at approximately 1000 hPa to initially load the ionic compound, resulting in the binding of 82 g of chlorine gas and liquefaction of the chlorine storage medium [NEt3Me]Cl. Therefore, the absorption capacity of [NEt3Me]Cl was 0.82 g chlorine gas / g ionic compound, and the dynamic viscosity of the liquid-loaded chlorine storage medium was 20 mPa·s. Raman spectroscopy revealed that the loaded chlorine storage medium consisted of a mixture of different trichlorides to nonachlorides, corresponding in form to [NEt3Me]Cl. 3.5.7.9 The storage medium under this load was unloaded at 1000 hPa and 60°C, releasing 29 grams of chlorine gas, which is equivalent to a release rate of 0.29 grams of chlorine gas per gram of ionic compound. The dynamic viscosity of the unloaded chlorine storage medium at 20°C was 46 mPa·s.
[0034] Compared to chlorine storage media based solely on triethylmethylammonium chloride, organic salts, when mixed with organic solvents, exhibit significantly lower viscosity and higher chlorine release rates. Furthermore, this chlorine storage medium remains a low-viscosity liquid within its operating range, making it suitable for applications such as gas filling and pipeline transportation. This chlorine storage medium effectively reduces the saturated vapor pressure of chlorine at room temperature, and in the event of an accidental leak, the chlorine release rate is very low, effectively minimizing the risk to environmental safety. Table 1: Comparison of chlorine release test performance of different chlorine storage media The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.
Claims
1. A chlorine storage medium, characterized in that, It is a mixture consisting of at least one organic salt and at least one organic solvent, wherein the organic salt is selected from one or more of tetraalkylphosphonium and tetraalkylamine, and the organic solvent is selected from one or more of bromobenzene, propylene glycol phenyl ether, 4-chlorodiphenyl ether, 3,4-dichlorodiphenyl ether, pyridine, 2-chloropyridine, and 2,4-dichloropyridine, and the chlorine storage medium is liquid at a temperature of 25°C and a pressure of 1000±100hPa.
2. The chlorine storage medium as described in claim 1, characterized in that, The organic salt is selected from at least one of the following compounds: trimethylethylammonium chloride, dimethyldiethylammonium chloride, methyltriethylammonium chloride, methyldiethylbutylammonium chloride, tripropylmethylammonium chloride, dibutyldimethylammonium chloride, and triethylmethylphosphoric acid chloride.
3. The chlorine storage medium as described in claim 1, characterized in that, The organic salt is selected from at least one of the following compounds: trimethylethylammonium chloride, dimethyldiethylammonium chloride, and methyltriethylammonium chloride.
4. The chlorine storage medium according to claim 1, characterized in that the organic solvent is one or both of 3,4-dichlorodiphenyl ether and 2,4-dichloropyridine.
5. The chlorine storage medium as described in claim 1, characterized in that it comprises 33.3 wt% triethylmethylammonium chloride and 66.7 wt% trimethylethylammonium chloride.
6. A method for storing chlorine gas in a self-storing chlorine medium, characterized in that, The chlorine-containing gas is brought into contact with a chlorine storage medium containing at least one organic salt and one organic solvent, wherein the organic salt is selected from one or more of tetraalkylphosphonium and tetraalkylammonium, and the organic solvent is selected from one or more of bromobenzene, propylene glycol phenyl ether, 4-chlorodiphenyl ether, 3,4-dichlorodiphenyl ether, pyridine, 2-chloropyridine, and 2,4-dichloropyridine, and the chlorine storage medium is liquid at a temperature of 25°C and a pressure of 1000±100 hPa.
7. A method for separating chlorine gas from a self-storing chlorine medium, characterized in that, Chlorine is released by heating a chlorine-loaded chlorine storage medium.
8. The method for separating chlorine gas from a self-storing chlorine medium as described in claim 7, characterized in that, Chlorine is released by depressurizing the chlorine-loaded storage medium.
9. The method for separating chlorine gas from a self-storing chlorine medium as described in claim 7, characterized in that, Chlorine is released by passing gas through a chlorine-loaded storage medium.