Method and system for recycling chlorine in hydrogen chloride based on cuprous chloride-hydrochloric acid system

Abstract

The invention discloses a method and a system for recycling chlorine in hydrogen chloride based on a cuprous chloride-hydrochloric acid system, and relates to the technical field of polyvinyl chloride production. CuCl reacts with saturated hydrochloric acid to generate a [CuCl2] <->, [CuCl3] < 2-> or [CuCl4] < 3-> complex solution, cuprous ions (Cu < + >) in the solution can efficiently capture chlorine molecules (Cl2) in hydrogen chloride (HCl) gas, and a trichloro copper acid (H2 [CuCl3]) or tetrachloro copper acid (H2 [CuCl4]) complex is formed. When the complex is heated, the complex can be decomposed to release chlorine, and meanwhile CuCl is reduced and can be recycled. By adopting the method provided by the invention, the single absorption efficiency can reach 95-98%. According to the method provided by the invention, the problem of explosion accidents caused by hydrogen chloride perchlorination in the PVC production process by a calcium carbide method is thoroughly solved; the chlorine-hydrogen ratio during hydrogen chloride synthesis is improved, and the purity control index of hydrogen chloride is improved, so that the yield of vinyl chloride is improved, and side reactions are reduced; the vinyl chloride tail gas treatment difficulty and cost are reduced; cuCl can be recycled, and the cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of polyvinyl chloride production, in particular to a method for recovering and utilizing chlorine in hydrogen chloride based on a cuprous chloride-hydrochloric acid system. Background Art

[0002] In the traditional calcium carbide-based polyvinyl chloride (PVC) production process, chlorine (Cl2) and hydrogen (H2) combust in a synthesis furnace to produce hydrogen chloride (HCl). This hydrogen chloride then reacts with acetylene in the presence of a catalyst to produce vinyl chloride. Explosions caused by overchlorination of HCl (referring to HCl gas containing excessive Cl2) and acetylene are common. Consequently, companies are forced to reduce the purity of the HCl and slightly increase the hydrogen overload, maintaining a chlorine-to-hydrogen ratio between 1:1 (1.05-1.1) and a HCl purity of 94-95%. This means that under normal production conditions, the HCl gas must be overhydrogenated (with a slightly greater molar ratio of hydrogen than chlorine) to ensure safe production. However, when production system fluctuations, operational errors, or other unidentified factors trigger an unexpected state, resulting in overchlorination of the HCl, the current approach is often to shut down the process by rapidly shutting down the acetylene within a very short reaction time to prevent explosions. Production is then restarted only after the chlorine is completely removed, severely impacting normal, safe, and continuous production efficiency.

[0003] Therefore, studying new ways to produce polyvinyl chloride by reaction and realizing the effective absorption and recycling of chlorine in HCl gas has become an urgent problem to be solved in current polyvinyl chloride production technology. Summary of the Invention

[0004] In view of the above shortcomings of the prior art, the present invention provides a method and system for recovering chlorine from hydrogen chloride based on a cuprous chloride-hydrochloric acid system. The present invention absorbs chlorine in a cuprous chloride-hydrochloric acid solution to generate a reaction containing [CuCl2] - , [CuCl3] 2- or [CuCl4] 3- The complex solution removes and recovers chlorine from hydrogen chloride. When heated, these complexes decompose to release chlorine, which is then recovered. CuCl and hydrochloric acid are also reduced and recycled. This is achieved through the following technologies.

[0005] The invention provides a method for recovering and utilizing chlorine in hydrogen chloride gas. The method comprises the following steps: introducing the hydrogen chloride gas containing chlorine into a cuprous chloride-hydrochloric acid solution for reaction to complete the absorption of the chlorine.

[0006] Furthermore, the reaction liquid that absorbed the chlorine is heated to release the chlorine for recycling, and the resulting solution containing cuprous chloride and HCl is recycled. The released chlorine can be absorbed and recovered using other process decontamination equipment. For example, a common process decontamination tower containing alkali solution can be used to absorb the chlorine.

[0007] Optionally, the heating temperature is 50-100°C.

[0008] Further optionally, the heating temperature is 60-90°C.

[0009] Preferably, the heating temperature is 70-80°C.

[0010] Furthermore, in the cuprous chloride-hydrochloric acid solution, the concentration of cuprous chloride is 0.5-2 mol / L.

[0011] Furthermore, in the cuprous chloride-hydrochloric acid solution, the concentration of HCl is 12-12.4 mol / L (mass fraction of about 36-38%).

[0012] By controlling the concentrations of cuprous chloride and HCl in the cuprous chloride-hydrochloric acid solution as described above, the absorption capacity for chlorine from hydrogen chloride can be guaranteed. A too low cuprous chloride concentration results in insufficient absorption, while a too high concentration results in excessive viscosity, which also affects chlorine absorption. The hydrochloric acid must be at a saturated concentration (specifically, 37-38%, 12-12.4 mol), which allows the CuCl to dissolve more easily and form a complex.

[0013] Furthermore, the mass fraction of chlorine in the hydrogen chloride gas is 5-15%.

[0014] The present invention provides a method for recovering and utilizing chlorine in hydrogen chloride gas, using Cl - Ligand-stabilized Cu + The d-electron configuration of the chlorine-containing chlorine gas increases the redox potential to +0.2-0.6V vs. SHE. It is particularly suitable for treating the accidental hydrogen chloride gas containing 5-15% Cl₂, which is generated during the calcium carbide-based PVC production process. Furthermore, the accompanying decontamination tower can realize chlorine recovery and the regeneration cycle of cuprous chloride-hydrochloric acid.

[0015] In the above-mentioned method for recovering chlorine from hydrogen chloride gas provided by the present invention, the absorption and adsorption of chlorine is achieved through the complex absorption mechanism of the cuprous chloride-hydrochloric acid system. Specifically, in the cuprous chloride-hydrochloric acid solution, cuprous chloride forms a complex such as [CuCl2] in concentrated hydrochloric acid. This absorption and adsorption reaction is reversible, mild, and highly selective. Cuprous ions (Cu +) can efficiently capture chlorine molecules (Cl2) in hydrogen chloride (HCl) gas. After chlorine absorption, it forms trichlorocupric acid (H2[CuCl3], also known as chlorocuprous acid) or tetrachlorocupric acid (H2[CuCl4], chlorocupric acid) complexes. The reaction process is as follows:

[0016] ;

[0017] .

[0018] The specific reaction path depends on the hydrochloric acid concentration and reaction temperature (usually 20-40℃). - Inhibit chlorine dissolution because according to the reaction , the equilibrium moves to the left; when using high concentration hydrochloric acid, H + The chemical dissolution of chlorine is enhanced by saturated hydrochloric acid (36-38% by mass), which balances the effects of dissolution inhibition and complexation promotion, optimizing absorption efficiency. Complexation absorption technology offers significant advantages in the PVC production process, including reversible reaction characteristics, room-temperature adsorption, and heated desorption.

[0019] The saturated hydrochloric acid in this system ensures the normal passage of hydrogen chloride, while the dissolved cuprous chloride quickly and thoroughly absorbs excess chlorine. The reversible reaction characteristics make it possible to regenerate the cuprous chloride.

[0020] The present invention also provides a chlorine recovery and utilization system in hydrogen chloride gas, comprising a packed absorption container, an absorption liquid container, and a heater; an air inlet and a first liquid outlet are provided at the bottom of the packed absorption container; a spray device and a first air outlet are provided at the top of the packed absorption container; the air inlet is used to introduce hydrogen chloride gas containing chlorine;

[0021] The absorption liquid container is provided with at least one; the absorption liquid container is provided with a first liquid inlet, a second liquid inlet, and a second air outlet, and is also provided with a second liquid outlet and a third liquid outlet; the first liquid outlet is connected to the first liquid inlet, and a regeneration pipe is provided between the second liquid inlet and the second liquid outlet, and the heater is used to heat the reaction liquid that absorbs chlorine in the regeneration pipe; the third liquid outlet is connected to the spraying equipment through a circulation pipe; the second air outlet is used to discharge chlorine; the regeneration pipe is provided with a first pump, and the circulation pipe is provided with a second pump.

[0022] In the above system, the packed absorption vessel absorbs chlorine from the hydrogen chloride gas, the absorption liquid vessel serves as a storage container for the cuprous chloride-hydrochloric acid solution, and the heater heats the cuprous chloride-hydrochloric acid reaction solution that has absorbed the chlorine. One or more absorption liquid vessels can be provided; if multiple absorption liquid vessels are provided, they can be used alternately.

[0023] It should be noted that when the chlorine concentration in the hydrogen chloride gas is too high (for example, exceeding 15%), a single packed absorption vessel may not fully absorb the chlorine. In this case, two or more packed absorption vessels can be connected in series. Generally, when producing polyvinyl chloride using the calcium carbide process, the chlorine content in the hydrogen chloride gas generally does not exceed 15%.

[0024] When preparing polyvinyl chloride by the calcium carbide method, the above system is operated when an abnormal situation of hydrogen chloride overchlorination occurs. At this time, the hydrogen chloride gas containing chlorine is passed into the packed absorption container, and the chlorine contained is absorbed by the sprayed cuprous chloride-concentrated hydrochloric acid complex solution. The purified hydrogen chloride gas is converted through the first gas outlet at the top of the container.

[0025] Once normal conditions are restored, the chlorine-containing reaction liquid in the absorption liquid container is pumped through a heater, where it is heated by steam to a predetermined temperature, reacting and releasing chlorine. The chlorine is then transported to a decontamination container for treatment. The reduced CuCl is then dissolved in concentrated hydrochloric acid to form a complex absorption liquid. Once tested and qualified, it is ready for use, enabling recycling.

[0026] Compared with the prior art, the present invention is beneficial in that:

[0027] 1. High efficiency and selectivity: The saturated hydrochloric acid environment can inhibit the hydrolysis of Cl2, while adsorbing and absorbing chlorine, and promoting the formation of chlorocuprous acid and / or chlorocupric acid; under the condition that the initial chlorine concentration is ≤10%, the single absorption efficiency is ≥99.9%, and the absorption rate is increased by more than 20% compared with the traditional method.

[0028] Saturated hydrochloric acid can ensure the lossless passage of hydrogen chloride, achieve normal continuity, abnormal effect, and ensure safe production.

[0029] 2. Reversible complexation: The generated complex releases chlorine after heating, and the reduced CuCl quickly dissolves in concentrated hydrochloric acid to form a complex, achieving the purpose of recycling, and the performance is basically not attenuated.

[0030] 3. Economic Advantages: The absorption liquid is virtually undamaged and can be heated with a small amount of steam after absorbing chlorine and then recycled for reuse. The system's operating energy consumption is reduced by over 40%, making it suitable for the removal of chlorine from hydrogen chloride in the tail gas of chemical chlorination processes, as well as for semiconductors, environmental protection, and other fields. This is particularly effective in resolving explosions caused by over-chlorination of hydrogen chloride during the production of PVC using the calcium carbide process, resolving safety issues while also generating significant economic benefits.

[0031] 4. Efficient absorption of chlorine increases the chlorine-hydrogen ratio during hydrogen chloride synthesis, creating conditions for improving the purity of hydrogen chloride, thereby increasing the yield of vinyl chloride in production, while reducing the occurrence of side reactions and alleviating the difficulty of tail gas treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the system for recovering and utilizing chlorine in hydrogen chloride gas provided by the present invention. DETAILED DESCRIPTION

[0033] The technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] In some embodiments of the present invention, a method for recovering chlorine from hydrogen chloride gas is provided, wherein the hydrogen chloride gas containing chlorine is passed into a cuprous chloride-hydrochloric acid solution to react and absorb the chlorine.

[0035] Optionally, during the above-mentioned reaction process of absorbing chlorine, the reaction temperature can be controlled to be normal temperature / room temperature.

[0036] For example, 20-40°C can be selected, and 25-30°C can further be selected.

[0037] Alternatively, the reaction solution that absorbed the chlorine can be heated to release the chlorine for recycling, and the resulting solution containing cuprous chloride and HCl can be recycled. Using this method, the chlorine can be recycled or passed into a process decontamination tower or other process decontamination equipment for further treatment. For example, a common process decontamination tower containing alkali solution can be used to absorb the chlorine. The resulting solution containing cuprous chloride and HCl can then be recycled to absorb the chlorine.

[0038] Further optionally, the heating temperature of the reaction liquid that has absorbed chlorine is 50-100°C.

[0039] Further optionally, the heating temperature is 60-90°C.

[0040] Preferably, the heating temperature is 70-80°C.

[0041] Furthermore, in the cuprous chloride-hydrochloric acid solution, the concentration of cuprous chloride is 0.5-2 mol / L.

[0042] Furthermore, in the cuprous chloride-hydrochloric acid solution, the concentration of HCl is 12-12.4 mol / L (mass fraction of about 36-38%).

[0043] By controlling the concentrations of cuprous chloride and HCl in the cuprous chloride-hydrochloric acid solution as described above, the absorption capacity for chlorine from hydrogen chloride can be guaranteed. A too low cuprous chloride concentration results in insufficient absorption, while a too high concentration results in excessive viscosity, which also affects chlorine absorption. The hydrochloric acid must be at a saturated concentration (specifically, 37-38%, 12-12.4 mol), which allows the CuCl to dissolve more easily and form a complex.

[0044] Furthermore, the mass fraction of chlorine in the hydrogen chloride gas is 5-15%.

[0045] The present invention provides a method for recovering and utilizing chlorine in hydrogen chloride gas, using Cl - Ligand-stabilized Cu + The d-electron configuration of the chlorine-containing chlorine gas increases the redox potential to +0.2-0.6V vs. SHE. It is particularly suitable for treating the accidental hydrogen chloride gas containing 5-15% Cl₂, which is generated during the calcium carbide-based PVC production process. Furthermore, the accompanying decontamination tower can realize chlorine recovery and the regeneration cycle of cuprous chloride-hydrochloric acid.

[0046] The present invention also provides a chlorine recovery and utilization system in hydrogen chloride gas, comprising a packed absorption container, an absorption liquid container, and a heater; an air inlet and a first liquid outlet are provided at the bottom of the packed absorption container; a spray device and a first air outlet are provided at the top of the packed absorption container; the air inlet is used to introduce hydrogen chloride gas containing chlorine;

[0047] The absorption liquid container is provided with at least one; the absorption liquid container is provided with a first liquid inlet, a second liquid inlet, and a second air outlet, and is also provided with a second liquid outlet and a third liquid outlet; the first liquid outlet is connected to the first liquid inlet, and a regeneration pipe is provided between the second liquid inlet and the second liquid outlet, and the heater is used to heat the reaction liquid that absorbs chlorine in the regeneration pipe; the third liquid outlet is connected to the spraying equipment through a circulation pipe; the second air outlet is used to discharge chlorine; the regeneration pipe is provided with a first pump, and the circulation pipe is provided with a second pump.

[0048] like Figure 1 As shown, the above-mentioned chlorine recovery and utilization system in hydrogen chloride gas is specially designed based on the chlorine recovery and utilization method in hydrogen chloride gas provided by the present invention and in combination with the problem of hydrogen chloride over-chlorination in the traditional calcium carbide method polyvinyl chloride production process.

[0049] like Figure 1As shown, in the following specific implementation cases: (1) The packed absorption container can be selected as a packed absorption tower, the specifications of the tower are specifically designed according to the production scale, and the built-in filler enhances the gas-liquid contact efficiency. (2) The absorption liquid container can be selected as an absorption liquid tank, and two absorption liquid tanks are connected in parallel with the packed absorption tower. The absorption liquid tank can be made of fiberglass, and the storage capacity is specifically designed according to the production scale. (3) The heater is a graphite heater, and the reaction liquid that absorbs chlorine is heated by steam heating; (4) The first pump is in Figure 1 is used as a regeneration pump in Figure 1 It is used as a circulation pump.

[0050] The system can also be equipped with a sealed explosion-proof structure and chlorine and hydrogen leak alarm systems to continuously monitor for chlorine and hydrogen leaks and ensure safe operation. Under normal production conditions, the system will not be activated if hydrogen chloride is not producing enough chlorine; however, the concentrations of cuprous chloride and hydrochloric acid in the solution must be constantly monitored, and adjustments must be made promptly if any deviations are detected.

[0051] When hydrogen chloride gas is superchlorinated, Figure 1 The specific operation process of the chlorine recovery and utilization system in hydrogen chloride gas is as follows:

[0052] (1) Start the circulation pump (second pump). The hydrogen chloride gas containing chlorine is introduced from the air inlet at the bottom of the packed absorption tower (packed absorption container). The cuprous chloride-hydrochloric acid solution is sprayed into the packed absorption tower from the spray equipment at the top of the packed absorption tower. The countercurrent flow of the hydrogen chloride gas containing chlorine and the cuprous chloride-hydrochloric acid solution, as well as the packing inside the packed absorption tower, enable the gas and liquid to fully contact and react.

[0053] The cuprous chloride-hydrochloric acid solution is supplied from the absorption tank via the third liquid outlet and the circulation pump. The two absorption tanks can be used alternately to provide sufficient cuprous chloride-hydrochloric acid solution.

[0054] (2) After the reaction is completed, relatively pure hydrogen chloride gas is discharged from the first gas outlet at the top of the packed absorption tower, and the reaction liquid that has absorbed chlorine gas flows back into the absorption tank through the first liquid outlet at the bottom of the packed absorption tower and the first liquid inlet of the absorption tank.

[0055] (3) When chlorine in hydrogen chloride gas is released, the circulation pump is turned off, the regeneration pump (first pump) and the graphite heater are started, hot steam flows into the graphite heater, and condensed water is discharged from the graphite heater; the cuprous chloride-hydrochloric acid solution in the absorption tank (or the reaction liquid that has absorbed chlorine) flows into the graphite heater, and the reaction temperature is controlled at 50-100°C, so that the chlorine in the reaction liquid is removed and regenerated, until the absorption liquid is reduced to cuprous chloride-hydrochloric acid solution, then the regeneration pump is stopped.

[0056] (4) The chlorine gas released is discharged through the second gas outlet at the top of the absorption tank and can be directly recovered or passed into a decontamination tower containing NaOH for further absorption.

[0057] When the entire system is running, the concentrations of CuCl and hydrochloric acid in the absorption liquid are monitored in real time or at regular intervals to keep them within the target range. If there is any deviation, they are replenished in time.

[0058] Example 1

[0059] The method for recovering chlorine from hydrogen chloride gas provided in this embodiment uses a cuprous chloride-hydrochloric acid solution prepared by adding cuprous chloride to saturated concentrated hydrochloric acid. The cuprous chloride concentration is 0.5 mol / L, and the HCl concentration is 12.4 mol / L (38% by mass). The mass fraction of chlorine in the introduced hydrogen chloride gas is 5%.

[0060] When the reaction liquid having absorbed chlorine gas was heated, the heating temperature was 60°C.

[0061] The cycle between the absorption tank and the packed absorption tower was initiated. Once stable, hydrogen chloride gas containing chlorine was introduced through the absorption tank and then into the packed absorption tower. The OMA-3010 Cl₂ & HCl analyzer was used for testing every 24 hours. Over 168 hours of continuous operation, the absorption rate fluctuation was less than 0.01%. The final test results showed no detectable Cl₂ content in the HCl gas, indicating a value of 0. Therefore, it was assumed that the Cl₂ had been completely absorbed.

[0062] Example 2

[0063] The method for recovering chlorine from hydrogen chloride gas provided in this embodiment uses a cuprous chloride-hydrochloric acid solution prepared by adding cuprous chloride to saturated concentrated hydrochloric acid. The cuprous chloride concentration is 2 mol / L, and the HCl concentration is 12.4 mol / L (38% by mass). The mass fraction of chlorine in the introduced hydrogen chloride gas is 5%.

[0064] When the reaction liquid having absorbed chlorine gas was heated, the heating temperature was 70°C.

[0065] After passing through the absorption liquid tank and then to the packed absorption tower, the OMA-3010 Cl2&HCl analyzer is used for detection. The Cl2 content in the HCl gas can no longer be detected, that is, the content number displayed is 0. Therefore, it can be considered that the Cl2 has been completely absorbed.

[0066] Example 3

[0067] The method for recovering chlorine from hydrogen chloride gas provided in this embodiment uses a cuprous chloride-hydrochloric acid solution prepared by adding cuprous chloride to saturated concentrated hydrochloric acid. The cuprous chloride concentration is 0.5 mol / L, and the HCl concentration is 12.4 mol / L (38% by mass). The mass fraction of chlorine in the introduced hydrogen chloride gas is 15%.

[0068] When the reaction liquid having absorbed chlorine gas was heated, the heating temperature was 80°C.

[0069] After passing through the absorption liquid tank and then to the packed absorption tower, the OMA-3010 Cl2&HCl analyzer was used for detection, and the Cl2 content in the HCl gas was detected to be reduced to 0.01%, that is, the chlorine absorption rate was 99.93%.

[0070] Example 4

[0071] The method for recovering chlorine from hydrogen chloride gas provided in this embodiment uses a cuprous chloride-hydrochloric acid solution prepared by adding cuprous chloride to saturated concentrated hydrochloric acid. The concentration of cuprous chloride is 2 mol / L, and the concentration of HCl is 12 mol / L (37% by mass). The mass fraction of chlorine in the introduced hydrogen chloride gas is 15%.

[0072] When the reaction liquid having absorbed chlorine gas was heated, the heating temperature was 80°C.

[0073] After passing through the absorption liquid tank and then to the packed absorption tower, the OMA-3010 Cl2&HCl analyzer was used for detection, and the Cl2 content in the HCl gas was detected to be reduced to 0.002%, that is, the chlorine absorption rate was 99.99%.

[0074] Comparative Example 1

[0075] The method for recovering chlorine from hydrogen chloride gas provided in this comparative example uses a cuprous chloride-hydrochloric acid solution having a cuprous chloride concentration of 0.4 mol / L. Other conditions and methods are the same as those in Example 1.

[0076] The final Cl₂ content in the HCl gas was detected to be 0.17%, and the chlorine absorption rate was 96.6%. This indicates that the low concentration of cuprous chloride (<0.5 mol / L) resulted in incomplete chlorine absorption.

[0077] Comparative Example 2

[0078] In the method for recovering chlorine from hydrogen chloride gas provided in this comparative example, the heating temperature is 55° C., and the other methods and conditions are the same as those in Example 2.

[0079] Finally, the Cl2 content in the HCl gas was intermittently detected to be 0.08-0.2%. Based on this, it can be judged that although the chlorine content in the original mixed gas was not high, only 5%, the low temperature prevented the complete release of chlorine, affecting its absorption.

[0080] Comparative Example 3

[0081] In the method for recovering chlorine from hydrogen chloride gas provided in this comparative example, the heating temperature is 55° C., and the other methods and conditions are the same as those in Example 3.

[0082] The final intermittent detection of Cl2 in the HCl gas was 0.1-0.45%. It can be seen that since the chlorine content in the original mixed gas reached 15%, the low temperature caused incomplete release of chlorine, resulting in a higher chlorine detection rate than Comparative Example 2, affecting the absorption of chlorine.

[0083] The above specific embodiments describe the implementation of the present invention in detail, but the present invention is not limited to the specific details of the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

Claims

1. A method for recovering chlorine from hydrogen chloride gas, characterized in that: The hydrogen chloride gas containing chlorine is passed into the cuprous chloride-hydrochloric acid solution to react and complete the absorption of chlorine.

2. The method for recovering chlorine from hydrogen chloride gas according to claim 1, wherein: The reaction liquid that has absorbed chlorine is heated to release the chlorine for recycling, and the resulting solution containing cuprous chloride and HCl is recycled.

3. The method for recovering chlorine from hydrogen chloride gas according to claim 2, wherein: The heating temperature is 50-100℃.

4. The method for recovering chlorine from hydrogen chloride gas according to claim 3, wherein: The heating temperature is 60-90℃.

5. The method for recovering chlorine from hydrogen chloride gas according to claim 4, characterized in that: The heating temperature is 70-80℃.

6. The method for recovering chlorine from hydrogen chloride gas according to claim 1, characterized in that: In the cuprous chloride-hydrochloric acid solution, the concentration of cuprous chloride is 0.5-2 mol / L.

7. The method for recovering chlorine from hydrogen chloride gas according to claim 1, characterized in that: In the cuprous chloride-hydrochloric acid solution, the concentration of HCl is 12-12.4 mol / L.

8. The method for recovering chlorine from hydrogen chloride gas according to claim 1, characterized in that: Using Cl - Ligand-stabilized Cu + The d-electron configuration of the 2-Hydroxy-2-nitrogen molecule increases the redox potential to +0.2-0.6 V vs. SHE.

9. The method for recovering chlorine from hydrogen chloride gas according to claim 1, characterized in that: The mass fraction of chlorine in the hydrogen chloride gas is 5-15%.

10. A system for recovering chlorine from hydrogen chloride gas, characterized in that: It includes a packed absorption container, an absorption liquid container and a heater; the bottom of the packed absorption container is provided with an air inlet and a first liquid outlet; the top of the packed absorption container is provided with a spray device and a first air outlet; the air inlet is used to introduce hydrogen chloride gas containing chlorine; The absorption liquid container is provided with at least one; the absorption liquid container is provided with a first liquid inlet, a second liquid inlet, and a second air outlet, and is also provided with a second liquid outlet and a third liquid outlet; the first liquid outlet is connected to the first liquid inlet, and a regeneration pipe is provided between the second liquid inlet and the second liquid outlet, and the heater is used to heat the reaction liquid that absorbs chlorine in the regeneration pipe; the third liquid outlet is connected to the spraying equipment through a circulation pipe; the second air outlet is used to discharge chlorine; the regeneration pipe is provided with a first pump, and the circulation pipe is provided with a second pump.

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