Method for producing regenerated refrigerant composition containing (e)-1,2-difluoroethylene

Abstract

The present invention provides a method for producing a regenerated refrigerant composition, with which disproportionation of the obtained regenerated refrigerant composition is suppressed as compared with conventional methods, and generation of an acid due to a reaction between the refrigerant composition and oxygen is suppressed.　Provided is a method for producing a regenerated refrigerant composition containing (E)-1,2-difluoroethylene, the method being characterized by: including step 1 for removing oxygen and water from a mixed refrigerant composition to be treated containing the (E)-1,2-difluoroethylene; and performing the step 1 under a pressure of 5 MPa∙G or less.

Description

Method for producing recycled refrigerant composition containing (E)-1,2-difluoroethylene

[0001] The present disclosure relates to a method for producing a recycled refrigerant composition comprising (E)-1,2-difluoroethylene.

[0002] (E)-1,2-Difluoroethylene (hereinafter also referred to as "R-1132(E)") has attracted attention as a refrigerant to replace difluoromethane (R-32) and 1,1,1,2,2-pentafluoroethane (R-125), which are greenhouse gases, due to its small global warming potential (GWP).

[0003] Patent Document 1 discloses a method for regenerating a refrigerant, comprising the steps of transferring an unregenerated refrigerant composition containing one or more hydrofluoroolefins from a source vessel to a treatment vessel, determining a target composition, determining one or more treatments based on the target composition, and performing at least one treatment selected from the group consisting of transferring, blending, distilling, nitrogen purging, filtration, dehydration, caustic scrubbing, decanting, and combinations thereof to form a partially regenerated refrigerant composition or a regenerated refrigerant composition.

[0004] Special Publication No. 2022-524758

[0005] The present disclosure aims to provide a method for producing a regenerated refrigerant composition in which disproportionation of the resulting regenerated refrigerant composition is suppressed compared to conventional methods, and in which acid generation due to reaction of the refrigerant composition with oxygen is suppressed.

[0006] The present disclosure includes, for example, the disclosures described in the following items. 1. A method for producing a recycled refrigerant composition containing (E)-1,2-difluoroethylene, comprising Step 1 of removing oxygen and water from a mixed refrigerant composition to be treated containing (E)-1,2-difluoroethylene, wherein Step 1 is carried out under a pressure of 5 MPa·G or less. 2. The production method described in Item 1, wherein Step 1 is a step of passing the mixed refrigerant composition to be treated through an adsorption tower containing at least a dehydrating agent, and the dehydrating agent is at least one selected from the group consisting of zeolite, silica gel, calcium chloride, and sodium sulfate. 3. The production method described in Item 1 or 2, wherein the method of removing oxygen in Step 1 is a method of passing the mixed refrigerant composition to be treated through an adsorption tower containing an oxygen scavenger and / or a method of removing oxygen using a distillation tower. 4. The production method described in Item 3, wherein the oxygen scavenger is at least one selected from the group consisting of metals, metal oxides, and organic oxygen scavengers. 5. Item 4. The manufacturing method according to any one of Items 1 to 4, wherein Step 1 is carried out under a pressure of 0.05 MPa·G or more. 6. The manufacturing method according to any one of Items 1 to 5, wherein Step 1 is carried out at a temperature of 150°C or less. 7. The manufacturing method according to any one of Items 1 to 6, wherein the content of (E)-1,2-difluoroethylene in the mixed refrigerant composition to be treated is more than 70% by mass and not more than 100% by mass, where the total content of refrigerants in the mixed refrigerant composition to be treated is 100% by mass, and Step 1 is carried out under a pressure of 1.5 MPa·G or less and at a temperature of 150°C or less. 8. The manufacturing method according to any one of Items 1 to 6, wherein the content of (E)-1,2-difluoroethylene in the mixed refrigerant composition to be treated is more than 50% by mass and not more than 70% by mass, where the total content of refrigerants in the mixed refrigerant composition to be treated is 100% by mass, and Step 1 is carried out under a pressure of 3 MPa·G or less and at a temperature of 150°C or less. 9. 7. The production method according to any one of Items 1 to 6, wherein the content of the (E)-1,2-difluoroethylene in the treated mixed refrigerant composition is 50% by mass or less, where the total content of refrigerants in the treated mixed refrigerant composition is 100% by mass, and Step 1 is carried out under a pressure of 5 MPa G or less and a temperature of 150°C or less.10. The method for producing a refrigerant composition according to any one of items 1 to 9, further comprising passing the refrigerant composition through an adsorption tower containing a deoxidizer in step 1. 11. The method for producing a refrigerant composition according to any one of items 1 to 10, further comprising step 2 of collecting the refrigerant composition.

[0007] According to the method for producing a regenerated refrigerant composition of the present disclosure, disproportionation of the resulting regenerated refrigerant composition is suppressed compared to conventional methods, and the generation of acid due to reaction of the refrigerant composition with oxygen can be suppressed.

[0008] 1A to 1C are schematic diagrams illustrating steps in a manufacturing method according to the present disclosure.

[0009] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0010] As used herein, the term "refrigerant" includes at least compounds assigned a refrigerant number (ASHRAE number) beginning with the letter R, which indicates the type of refrigerant, as defined by ISO 817 (International Organization for Standardization), and also includes compounds that have equivalent refrigerant properties even if they have not yet been assigned a refrigerant number. Refrigerants are broadly classified into "fluorocarbon compounds" and "non-fluorocarbon compounds" based on their chemical structure. "Fluorocarbon compounds" include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). "Non-fluorocarbon compounds" include propane (R290), propylene (R1270), butane (R600), isobutane (R600a), carbon dioxide (R744), and ammonia (R717).

[0011] Compositions containing refrigerants include at least (1) the refrigerant itself (including a mixture of refrigerants), (2) a composition that further contains other components and can be used to obtain a working fluid for a refrigerant by mixing with at least a refrigerating machine oil, and (3) a working fluid for a refrigerant containing a refrigerating machine oil. Of these three aspects, the composition (2) will be referred to as a "refrigerant composition" in this specification to distinguish it from the refrigerant itself (including a mixture of refrigerants). In the production method of the present disclosure, the mixed refrigerant composition to be treated and used as a feed gas recovered from the market or the like may contain oil such as the refrigerating machine oil.

[0012] The method for producing a recycled refrigerant composition containing (E)-1,2-difluoroethylene according to the present disclosure includes Step 1 of removing oxygen and water from the treated mixed refrigerant composition containing (E)-1,2-difluoroethylene, and is characterized in that Step 1 is carried out under a pressure of 5 MPa G or less.

[0013] The production method of the present disclosure includes step 1 of removing oxygen and water from a used, recovered mixed refrigerant composition to be treated, and therefore can produce a regenerated refrigerant composition containing (E)-1,2-difluoroethylene (R-1132(E)), thereby producing a regenerated refrigerant composition containing R-1132(E). Furthermore, in the production method of the present disclosure, step 1 is carried out under a pressure of 5 MPa·G or less, thereby suppressing disproportionation. Furthermore, the production method of the present disclosure can suppress the generation of acid due to the reaction of the refrigerant composition with oxygen.

[0014] The disclosed manufacturing methods allow for refrigerant regeneration, which as used herein refers to reprocessing of refrigerants to remove oil, water, acidity, and other impurities that may adversely affect the quality, i.e., performance, of the refrigerant.

[0015] The recycled refrigerant composition produced by the manufacturing method of the present disclosure is a refrigerant composition obtained by recycling used (or recovered) treated mixed refrigerants so as to meet the quality standards of AHRI 700. The quality of the refrigerant can be verified by analytical techniques such as GC-FID, GC-TCD GC-MS, FTIR, Goetz Bub, Karl Fischer, Byk-Garner Color, and various other analytical methods.

[0016] (Step 1) The mixed refrigerant composition to be treated used in step 1 of the production method of the present disclosure is a mixed refrigerant composition to be treated (feed gas) recovered from the market or the like. The lower limit of the R-1132(E) content in the feed gas is not particularly limited, and can be 0.1 mass% or more, 1 mass% or more, 10 mass% or more, 20 mass% or more, 25 mass% or more, 30 mass% or more, 40 mass% or more, 50 mass% or more, or 70 mass% or more, based on 100 mass% of the feed gas. The upper limit of the R-1132(E) content in the feed gas is also not particularly limited, and can be 100 mass% or less, 99.9 mass% or less, or 99.5 mass% or less, based on 100 mass% of the feed gas.

[0017] In the production method of the present disclosure, step 1 is carried out under a pressure of 5 MPa·G or less. If the pressure exceeds 5 MPa, disproportionation of the produced recycled refrigerant composition cannot be suppressed. The pressure is preferably 4 MPa or less, more preferably 3 MPa or less, even more preferably 1 MPa or less, and particularly preferably 0.5 MPa or less. There are no particular restrictions on the lower limit of the pressure, but it is preferably 0.01 MPa or more, more preferably 0.03 MPa or more, and even more preferably 0.05 MPa or more. By keeping the lower limit of the pressure within the above range, it is possible to suppress the incorporation of external gas into the reaction system.

[0018] In this specification, pressure means gauge pressure.

[0019] In the production method of the present disclosure, the temperature conditions when carrying out step 1 are preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 100°C or lower. When the upper limit of the temperature conditions is within the above range, disproportionation of the produced regenerated refrigerant composition can be further suppressed. Furthermore, the temperature conditions when carrying out step 1 are preferably -53°C or higher, more preferably 0°C or higher, and even more preferably temperature conditions exceeding 0°C. When the lower limit of the temperature conditions is within the above range, the mixed refrigerant composition to be treated is in a liquid or gas state, which is desirable because it makes step 1 easier. When the upper limit of the temperature conditions is within the above range, disproportionation can be further suppressed.

[0020] In the production method of the present disclosure, suitable pressure and temperature conditions for step 1 may be set depending on the range of the R-1132(E) content in the mixed refrigerant composition to be treated. Hereinafter, explanations will be given according to the range of the R-1132(E) content in the mixed refrigerant composition to be treated. In each of the following cases (1) to (3), the content of (E)-1,2-difluoroethylene is the content when the total content of the refrigerants in the mixed refrigerant composition to be treated is taken as 100% by mass. The above refrigerant refers to, for example, R-1132(E), R-1234yf, etc., and does not include impurities such as oil contained in the mixed refrigerant composition to be treated.

[0021] ((1) R-1132(E) Content: More than 70% by mass and 100% by mass or less) When the R-1132(E) content in the mixed refrigerant composition to be treated is more than 70% by mass and 100% by mass or less, where the total content of refrigerants in the mixed refrigerant composition to be treated is 100% by mass, the pressure condition in step 1 is preferably 1.5 MPa G or less, more preferably 1 MPa G or less, and even more preferably 0.5 MPa G or less. In this case, the lower limit of the pressure condition in step 1 is not particularly limited, and may be 0.01 MPa or more, 0.03 MPa or more, or 0.05 MPa or more. When the content of R-1132(E) in the treated mixed refrigerant composition is more than 70% by mass and not more than 100% by mass, where the total content of refrigerants in the treated mixed refrigerant composition is 100% by mass, by keeping the pressure conditions in step 1 within the above range, disproportionation of the resulting regenerated refrigerant composition is further suppressed, and the generation of acid due to the reaction of the refrigerant composition with oxygen is further suppressed.

[0022] When the content of R-1132(E) in the treated mixed refrigerant composition is more than 70% by mass and less than or equal to 100% by mass, where the total content of refrigerants in the treated mixed refrigerant composition is 100% by mass, the temperature conditions in step 1 are preferably 150°C or less, more preferably 100°C or less, and even more preferably 50°C or less. In this case, the upper limit of the temperature conditions in step 1 is not particularly limited, and it may be about 200°C or less. In this case, the lower limit of the temperature conditions in step 1 is not particularly limited, and may be -79°C or more, -30°C or more, 0°C or more, or 20°C or more. When the content of R-1132(E) in the treated mixed refrigerant composition is more than 70% by mass and less than or equal to 100% by mass, where the total content of refrigerants in the treated mixed refrigerant composition is 100% by mass, by setting the temperature conditions in step 1 within the above range, disproportionation of the resulting regenerated refrigerant composition is further suppressed, and the generation of acid due to the reaction of the refrigerant composition with oxygen is further suppressed.

[0023] (2) R-1132(E) Content: More than 50% by mass and Not More than 70% by mass When the content of R-1132(E) in the treated mixed refrigerant composition is more than 50% by mass and not more than 70% by mass, where the total content of refrigerants in the treated mixed refrigerant composition is 100% by mass, the pressure conditions in step 1 are preferably 3 MPa·G or less, and more preferably 2 MPa·G or less. In this case, the lower limit of the pressure conditions in step 1 is not particularly limited, and may be 0.01 MPa or more, 0.03 MPa or more, or 0.05 MPa or more. When the content of R-1132(E) in the treated mixed refrigerant composition is more than 50% by mass and not more than 70% by mass, where the total content of refrigerants in the treated mixed refrigerant composition is 100% by mass, by keeping the pressure conditions in step 1 within the above range, disproportionation of the resulting regenerated refrigerant composition is further suppressed, and the generation of acid due to the reaction of the refrigerant composition with oxygen is further suppressed.

[0024] When the content of R-1132(E) in the treated mixed refrigerant composition is more than 50% by mass and not more than 70% by mass, where the total content of refrigerants in the treated mixed refrigerant composition is 100% by mass, the temperature conditions in step 1 are preferably 150°C or less, more preferably 100°C or less. In this case, the upper limit of the temperature conditions in step 1 is not particularly limited, and it may be about 200°C or less. In this case, the lower limit of the temperature conditions in step 1 is not particularly limited, and may be -79°C or more, -30°C or more, 0°C or more, or 20°C or more. When the content of R-1132(E) in the treated mixed refrigerant composition is more than 50% by mass and not more than 70% by mass, where the total content of refrigerants in the treated mixed refrigerant composition is 100% by mass, by setting the temperature conditions in step 1 within the above range, disproportionation of the resulting regenerated refrigerant composition is further suppressed, and the generation of acid due to the reaction of the refrigerant composition with oxygen is further suppressed.

[0025] (3) R-1132(E) Content: 50% by Mass or Less When the content of R-1132(E) in the treated mixed refrigerant composition is 50% by mass or less, relative to 100% by mass of the total refrigerant content in the treated mixed refrigerant composition, the pressure conditions in step 1 are preferably 5 MPa·G or less, and more preferably 4 MPa·G or less. In this case, the lower limit of the pressure conditions in step 1 is not particularly limited, and may be 0.01 MPa or more, 0.03 MPa or more, or 0.05 MPa or more. When the content of R-1132(E) in the treated mixed refrigerant composition is 50% by mass or less, relative to 100% by mass of the total refrigerant content in the treated mixed refrigerant composition, by setting the pressure conditions in step 1 within the above range, disproportionation of the resulting regenerated refrigerant composition is further suppressed, and the generation of acid due to the reaction of the refrigerant composition with oxygen is further suppressed.

[0026] When the content of R-1132(E) in the treated mixed refrigerant composition is 50% by mass or less, relative to 100% by mass of the total refrigerant content in the treated mixed refrigerant composition, the temperature conditions in step 1 are preferably 150°C or less. In this case, the upper limit of the temperature conditions in step 1 is not particularly limited, and it may be about 200°C or less. In this case, the lower limit of the temperature conditions in step 1 is not particularly limited, and may be −79°C or more, −30°C or more, 0°C or more, or 20°C or more. When the content of R-1132(E) in the treated mixed refrigerant composition is 50% by mass or less, relative to 100% by mass of the total refrigerant content in the treated mixed refrigerant composition, by setting the temperature conditions in the above range, disproportionation of the resulting regenerated refrigerant composition is further suppressed, and the generation of acid due to the reaction of the refrigerant composition with oxygen is further suppressed.

[0027] In step 1, oxygen and water are removed from the mixed refrigerant composition to be treated. In step 1, oxygen is preferably removed from the mixed refrigerant composition to be treated by passing it through an adsorption tower containing at least a dehydrating agent.

[0028] The dehydrating agent is not particularly limited, and may be zeolite, silica gel, calcium chloride, sodium sulfate, etc. Among these, zeolite is preferred from the viewpoint of superior dehydrating properties.

[0029] The dehydrating agent may be used alone or in combination of two or more.

[0030] When the capacity of the adsorption tower is about 50 to 100 cc, the amount of dehydrating agent used in the adsorption tower is preferably 10 to 60 g, more preferably 20 to 50 g. By setting the lower limit of the amount of dehydrating agent used within the above range, dehydration of the regenerated refrigerant composition becomes more sufficient. By setting the upper limit of the amount of dehydrating agent used within the above range, gas flow in the reaction apparatus becomes good, and production efficiency is further improved.

[0031] In this specification, when an adsorption tower contains only a dehydrating agent and does not contain an oxygen scavenger, a deoxidizer, or the like, which will be described later, the adsorption tower is also referred to as a "dehydration tower."

[0032] The method for removing oxygen from the treated mixed refrigerant composition is not particularly limited, and examples include a method in which the treated mixed refrigerant composition is added to the dehydrating agent and then passed through an adsorption tower containing an oxygen scavenger, and a method in which oxygen is removed by utilizing the difference in the boiling point of the treated mixed refrigerant composition and the boiling point of oxygen. Methods for removing oxygen by utilizing the difference in the boiling point of the treated mixed refrigerant composition and the boiling point of oxygen include a method in which oxygen is removed using a distillation tower, and a method in which the treated mixed refrigerant composition is cooled to form a liquid or solid and then the gaseous oxygen is removed. These methods may be used alone or in combination of two or more.

[0033] The oxygen scavenger is not particularly limited, and metals, metal oxides, metal salts, organic oxygen scavengers, sulfates, etc. can be used.

[0034] The metal may be iron, and iron powder may be preferably used.

[0035] The metal oxide may be any metal oxide other than the metal oxide used as the dehydrating agent, and specifically, triiron tetroxide or the like may be used.

[0036] Examples of the organic oxygen absorber include vitamin C.

[0037] When the capacity of the adsorption tower is about 50 to 100 cc, the amount of oxygen scavenger used is preferably 10 to 60 g, more preferably 20 to 50 g, in the adsorption tower. By setting the lower limit of the amount of oxygen scavenger used within the above range, oxygen removal from the regenerated refrigerant composition becomes more sufficient. By setting the upper limit of the amount of oxygen scavenger used within the above range, gas flow in the reaction apparatus becomes good, and production efficiency is further improved.

[0038] When an adsorption tower is used in the production method of the present disclosure, the adsorption tower may contain other additives such as a polymerization inhibitor and a stabilizer in addition to the dehydrating agent and oxygen scavenger. When an adsorption tower is used in the production method of the present disclosure, a single adsorption tower may contain other additives such as a dehydrating agent, an oxygen scavenger, a polymerization inhibitor, and a stabilizer, or multiple adsorption towers containing these additives separately may be connected in series. Furthermore, multiple adsorption towers containing a combination of multiple other additives such as a dehydrating agent, an oxygen scavenger, a polymerization inhibitor, and a stabilizer may be connected in series. Note that the other additives such as the polymerization inhibitor and stabilizer may be used by being configured to be contained in the adsorption tower, or may be added to the mixed refrigerant composition to be treated.

[0039] Examples of polymerization inhibitors that can be used include limonene and terpenes. Adding a polymerization inhibitor to the adsorption tower allows the dehydrating agent and oxygen scavenger to be regenerated. The polymerization inhibitor may be contained in the adsorption tower, or may be added to the mixed refrigerant composition to be treated. When a polymerization inhibitor is used as described above, the polymerization inhibitor eluted from the adsorption tower into the mixed refrigerant composition to be treated, or the polymerization inhibitor added to the mixed refrigerant composition to be treated, will be mixed into the mixed refrigerant composition to be treated. However, connecting an adsorption tower containing silica gel allows the polymerization inhibitor mixed into the mixed refrigerant composition to be removed. The adsorption tower containing silica gel is preferably connected after the adsorption tower containing the polymerization inhibitor. The polymerization inhibitor may be contained in the adsorption tower, or may be added to the mixed refrigerant composition to be treated.

[0040] Examples of stabilizers that can be used include dibutylhydroxytoluene (BHT) and butylhydroxyanisole (BHA). When the mixed refrigerant composition to be treated passes through the adsorption tower, the R-1132(E) may polymerize or decompose due to the influence of the dehydrating agent, oxygen scavenger, and other additives. Adding a stabilizer to the adsorption tower can suppress the polymerization and decomposition of R-1132(E). The stabilizer may be contained in the adsorption tower, or may be added to the mixed refrigerant composition to be treated.

[0041] In the production method of the present disclosure, oxygen may be removed from the mixed refrigerant composition to be treated using a distillation column. The distillation column is not particularly limited, and any known distillation column can be used.

[0042] The distillation temperature when removing oxygen using a distillation column is preferably 50 to 250°C, more preferably 80 to 200°C, further preferably 100 to 180°C, and particularly preferably 130 to 170°C.

[0043] In the production method of the present disclosure, the adsorption tower may further contain an acid scavenger. By containing an acid scavenger in the adsorption tower, acid components generated by reaction between R-1132(E) in the mixed refrigerant composition to be treated and oxygen in the air mixed into the mixed refrigerant composition to be treated can be removed simultaneously with water removal by the adsorption tower.

[0044] The deoxidizing agent is not particularly limited, and soda lime, sodium hydroxide, potassium hydroxide, etc. can be used. Among these, soda lime is preferred from the viewpoint of easier removal of acid components.

[0045] When the capacity of the adsorption tower is about 50 to 100 cc, the amount of deoxidizer used in the adsorption tower is preferably 10 to 60 g, more preferably 20 to 50 g. By setting the lower limit of the amount of deoxidizer used within the above range, the acid components in the regenerated refrigerant composition can be more sufficiently removed. By setting the upper limit of the amount of deoxidizer used within the above range, the gas flow in the reaction apparatus is improved, and production efficiency is further improved.

[0046] The deoxidizing agent may be contained in an adsorption tower containing a dehydrating agent and an oxygen scavenger, or may be contained in a separate adsorption tower incorporated into the reaction system.

[0047] When the deoxidizing agent is contained in an adsorption tower separate from the adsorption tower containing the dehydrating agent and oxygen scavenger, the adsorption tower containing the deoxidizing agent is preferably installed before the adsorption tower containing the dehydrating agent and oxygen scavenger. By adopting this configuration, the deoxidizing agent is captured in the adsorption tower containing the dehydrating agent and oxygen scavenger, and the deoxidizing agent can be removed from the produced regenerated refrigerant composition.

[0048] By the above-described step 1, a recycled refrigerant composition containing (E)-1,2-difluoroethylene can be produced.

[0049] (Cooling step) Step 1 may include a cooling step of cooling the obtained regenerated refrigerant composition to obtain a liquefied or solidified regenerated refrigerant composition before Step 2 described below. By including the cooling step in Step 1, the produced regenerated refrigerant composition can be recovered more efficiently.

[0050] The cooling method for cooling the regenerated refrigerant composition is not particularly limited. For example, as shown in FIG. 1 , the mixed refrigerant composition to be treated is passed through an adsorption tower 12 containing a dehydrating agent and an oxygen scavenger to produce a regenerated refrigerant composition, and the regenerated refrigerant composition is then recovered in a cylinder 13 immersed in a cooling vessel filled with liquid nitrogen 14 as a cryogen.

[0051] The lower limit of the cooling temperature in the cooling step is preferably −230° C. or higher, more preferably −210° C. or higher. The upper limit of the cooling temperature in the cooling step is preferably 50° C. or lower, 25° C. or lower, 0° C. or lower, −50° C. or lower, −100° C. or lower, −150° C. or lower, or −170° C. or lower. By keeping the cooling temperature within the above range, the recycled refrigerant composition produced by the production method of the present disclosure can be recovered more efficiently.

[0052] When step 1 includes a cooling step, oxygen may be removed by degassing the cylinder used in the cooling step in the production method of the present disclosure. That is, as shown in Figure 1, degassing may be performed in cylinder 13 when the recycled refrigerant composition is recovered in cylinder 13 immersed in a cooling vessel filled with liquid nitrogen 14 as a cryogen.

[0053] By the above-described step 1, oxygen and water can be removed from the treated mixed refrigerant composition containing (E)-1,2-difluoroethylene.

[0054] (Step 2) The production method of the present disclosure may further include step 2 of collecting the recycled refrigerant composition after step 1. By including step 2 in the production method of the present disclosure, the produced recycled refrigerant composition can be collected in a collecting container with a larger capacity.

[0055] The method for collecting the regenerated refrigerant composition is not particularly limited. The container containing the regenerated refrigerant composition obtained in step 1 can be connected to a larger capacity collection container and the pressure reduced, thereby collecting the regenerated refrigerant composition in the collection container.

[0056] In step 2, the collecting vessel is preferably cooled by immersion in an ice bath. The cooling temperature is preferably −10° C. to 10° C., more preferably −5° C. to 5° C. By keeping the cooling temperature within the above range, the recycled refrigerant composition can be collected more stably in the collecting vessel.

[0057] According to the manufacturing method of the present disclosure described above, a treated mixed refrigerant composition recovered from the market can be regenerated to produce a regenerated refrigerant composition containing (E)-1,2-difluoroethylene. The regenerated refrigerant composition produced by the manufacturing method of the present disclosure has a low global warming potential (GWP) and can be suitably used as a refrigerant to replace the greenhouse gases difluoromethane (R-32) and 1,1,1,2,2-pentafluoroethane (R-125). According to the manufacturing method of the present disclosure, disproportionation of the regenerated refrigerant composition produced is suppressed, and acid generation due to reaction of the refrigerant composition with oxygen can be suppressed, thereby enabling the suitable production of a regenerated refrigerant composition containing (E)-1,2-difluoroethylene.

[0058] The present disclosure will be described in more detail below with reference to examples and comparative examples, but the present disclosure is not limited to the examples.

[0059] Example 1 A regenerated refrigerant composition containing (E)-1,2-difluoroethylene was produced using a production apparatus similar to that shown in Figure 1. Specifically, a container 11 containing a mixed refrigerant composition to be treated that had been recovered from the market was prepared and connected to the production apparatus. The mixed refrigerant composition to be treated in a gas phase was then fed into the production apparatus, and the mixed refrigerant composition to be treated was passed through an adsorption tower 12 containing a deoxidizing agent and a dehydrating agent to remove water and acid. The mixed refrigerant composition to be treated was recovered in a cylinder 13 immersed in a cooling vessel filled with liquid nitrogen 14 as a cryogen. Next, a degassing operation was performed in the cylinder 13 to remove oxygen from the mixed refrigerant composition to produce a regenerated refrigerant composition.

[0060] The production of the regenerated refrigerant composition containing (E)-1,2-difluoroethylene was carried out under the following conditions. Note that while FIG. 1 shows an example in which one adsorption tower 12 is provided, in Example 1, the mixed refrigerant composition to be treated was passed from the supply side through a deoxidation tower and then through a dehydration tower connected in series to the deoxidation tower. Pressure in the reaction system: 0.05 to 0.1 MPa·G Temperature in the reaction system: 23°C Cylinder degassing operation: 1 time / 100 g Deoxidation tower: capacity 68 cc Deoxidation agent: soda lime, packed amount 43 g Rate through the deoxidation tower: 5 g / min Dehydration tower: capacity 68 cc, dehydration agent MS (molecular sieve (zeolite)), packed amount 43 g MS regeneration conditions: reduced pressure at 150°C, regeneration time 3 hours or more Rate through the dehydration tower: 5 g / min, moisture value reduced from 282 ppm to 8 ppm

[0061] Example 2 A gaseous mixed refrigerant composition to be treated was fed into a production apparatus and passed through an adsorption tower (dehydration tower) 12 containing a dehydrating agent but not an oxygen scavenger. The mixed refrigerant composition to be treated was then passed through a distillation tower after the adsorption tower (dehydration tower) 12 to be deoxygenated. A regenerated refrigerant composition containing (E)-1,2-difluoroethylene was produced in the same manner as in Example 1 except for the above.

[0062] The production of the recycled refrigerant composition containing (E)-1,2-difluoroethylene in the distillation column was carried out under the following conditions: Dehydration column throughput: 80 g / min, Dehydration column pressure: 0.4 to 0.6 MPa·G, Dehydration column temperature: 2 to 6°C, Distillation temperature: 35°C

[0063] (Evaluation Method) The recycled refrigerant compositions obtained in the examples were evaluated as follows.

[0064] (Composition of Regenerated Refrigerant Composition) The composition of the regenerated refrigerant composition was analyzed using gas chromatography (MS detector).

[0065] (Moisture Content) The moisture content in the regenerated refrigerant composition was measured using a Karl Fischer moisture content analyzer.

[0066] (Acid Content) The acid content was measured by immersing a pH test paper in the regenerated refrigerant composition.

[0067] (Oxygen Concentration) The oxygen concentration of the regenerated refrigerant composition was measured using an oxygen concentration meter.

[0068] (Evaporation Residue) The evaporation residue of refrigerating machine oil and the like in the regenerated refrigerant composition was measured based on the AHRI 700 standard.

[0069] The results are shown in Table 1.

[0070]

[0071] The results in Table 1 show that in Examples 1 and 2, the water content, evaporation residue (refrigerating machine oil, etc.), acid content, and oxygen content in the regenerated refrigerant composition after regeneration were lower than those in the treated mixed refrigerant composition before regeneration, and that a regenerated refrigerant composition could be produced.

[0072] The results in Table 1 also show that disproportionation was suppressed in Examples 1 and 2. Furthermore, it was found that the generation of acids due to the reaction between the refrigerant composition and oxygen was suppressed in Example 1, and that the generation of acids was suppressed in Example 2 due to the removal of oxygen.

[0073] 11: Container containing the mixed refrigerant composition to be treated 12: Adsorption tower 13: Cylinder 14: Liquid nitrogen

Claims

1. A method for producing a recycled refrigerant composition containing (E)-1,2-difluoroethylene, comprising Step 1 of removing oxygen and water from the treated mixed refrigerant composition containing (E)-1,2-difluoroethylene, wherein Step 1 is carried out under a pressure of 5 MPa·G or less.

2. The manufacturing method according to claim 1, wherein step 1 is a step of passing the mixed refrigerant composition to be treated through an adsorption tower containing at least a dehydrating agent, and the dehydrating agent is at least one selected from the group consisting of zeolite, silica gel, calcium chloride, and sodium sulfate.

3. The manufacturing method according to claim 2, wherein the method for removing oxygen in step 1 is a method for passing the treated mixed refrigerant composition through an adsorption tower containing an oxygen scavenger and / or a method for removing oxygen using a distillation tower.

4. The manufacturing method according to claim 3, wherein the oxygen scavenger is at least one selected from the group consisting of metals, metal oxides, and organic oxygen scavengers.

5. The manufacturing method according to claim 1, wherein step 1 is carried out under a pressure of 0.05 MPa·G or more.

6. The manufacturing method according to claim 1, wherein step 1 is carried out at a temperature of 150°C or less.

7. The production method according to claim 1, wherein the content of (E)-1,2-difluoroethylene in the treated mixed refrigerant composition is more than 70 mass% and not more than 100 mass%, where the total content of refrigerants in the treated mixed refrigerant composition is 100 mass%, and step 1 is carried out under a pressure of not more than 1.5 MPa G and a temperature of not more than 150°C.

8. The manufacturing method according to claim 1, wherein the content of (E)-1,2-difluoroethylene in the treated mixed refrigerant composition is more than 50 mass% and not more than 70 mass%, where the total content of refrigerants in the treated mixed refrigerant composition is 100 mass%, and step 1 is carried out under a pressure of not more than 3 MPa G and a temperature of not more than 150°C.

9. The production method according to claim 1, wherein the content of (E)-1,2-difluoroethylene in the treated mixed refrigerant composition is 50 mass% or less, where the total content of refrigerants in the treated mixed refrigerant composition is 100 mass%, and step 1 is carried out under a pressure of 5 MPa G or less and a temperature of 150°C or less.

10. The method of claim 1, wherein step 1 further comprises passing the product through an adsorption tower containing a deoxidizer.

11. The method of claim 1, further comprising step 2 of aggregating the recycled refrigerant composition.

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