Refrigerant-containing compositions and methods of stabilizing refrigerant-containing compositions

Abstract

The present application aims to provide a composition having excellent stability of a refrigerant. The composition of the present application is characterized by containing a refrigerant and carbon, the above-mentioned refrigerant comprising at least one or more selected from the group consisting of HFO-1234yf, HFO-1132 (E / Z), HFO-1132a, HFO-1123 and FO-1114.

Description

Technical Field

[0001] This invention relates to compositions containing refrigerants and methods for stabilizing refrigerant-containing compositions. Background Technology

[0002] Patent Document 1 discloses a refrigeration cycle having an electric compressor, a condenser, an expansion valve, and an evaporator, and a circulation path connecting them, wherein a refrigerant such as 2,3,3,3-tetrafluoropropylene (HFO-1234yf) and lubricating oil circulate in the circulation path, wherein an acid neutralizer is provided in the circulation path having a neutralizing agent to neutralize the acid generated in the circulation path and an adsorbent to adsorb moisture, wherein zeolite, activated carbon, alumina, or silica gel are used as the adsorbent.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-220594 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] The purpose of this invention is to provide a composition with excellent refrigerant stability.

[0008] Technical solutions for solving technical problems

[0009] The present invention includes the solutions described in the following items.

[0010] Item 1. A composition containing a refrigerant and carbon, characterized in that the refrigerant comprises at least one compound represented by a molecular formula having one or more carbon-carbon unsaturated bonds.

[0011] Item 2. The composition as described in Item 1 above, wherein the refrigerant comprises at least one selected from 2,3,3,3-tetrafluoropropylene (HFO-1234yf), trans-1,2-difluoroethylene (HFO-1132(E)), cis-1,2-difluoroethylene (HFO-1132(Z)), 1,1-difluoroethylene (HFO-1132a), trifluoroethylene (HFO-1123) and tetrafluoroethylene (FO-1114).

[0012] Item 3. The composition as described in Item 1 or 2 above, wherein the composition contains more than 1 ppm of the carbon by weight relative to the refrigerant.

[0013] Item 4. The composition as described in any one of items 1 to 3 above, wherein the composition further contains water.

[0014] Item 5. The composition as described in Item 4 above, wherein the composition contains at least 10 ppm of the water by weight.

[0015] Item 6. The composition as described in any one of items 1 to 5 above, wherein the composition further comprises refrigeration oil, and the composition is used as a working fluid containing refrigeration oil.

[0016] Item 7. A method for stabilizing a refrigerant-containing composition, wherein the method includes a step of containing carbon in the composition, wherein the refrigerant is an ingredient comprising at least one compound represented by a molecular formula having one or more carbon-carbon unsaturated bonds.

[0017] Item 8. The method as described in Item 7 above, wherein the refrigerant is at least one component selected from 2,3,3,3-tetrafluoropropylene (HFO-1234yf), trans-1,2-difluoroethylene (HFO-1132(E)), cis-1,2-difluoroethylene (HFO-1132(Z)), 1,1-difluoroethylene (HFO-1132a), trifluoroethylene (HFO-1123) and tetrafluoroethylene (FO-1114).

[0018] Item 9. The method as described in Item 7 or 8 above, comprising: a step of containing more than 1 ppm of the carbon by weight relative to the refrigerant.

[0019] Item 10. The method as described in any one of items 7 to 9 above, comprising: a step of further containing water in the composition.

[0020] Item 11. The method as described in Item 10 above, comprising: a step of containing the water described above in the composition at a weight of 10 ppm or more.

[0021] The effects of the invention

[0022] The refrigerant in the composition of the present invention exhibits excellent stability. Detailed Implementation

[0023] After conducting in-depth research in order to improve the stability of refrigerants, the inventors of this invention discovered that this objective can be achieved by having at least one component selected from HFO-1234yf, HFO-1132(E / Z), HFO-1132a, HFO-1123 and FO-1114 coexist with carbon.

[0024] The inventors of this invention have discovered that when water is present in the composition, the stability of the refrigerant can be further improved by allowing carbon to coexist.

[0025] The embodiments included in this invention will be described in detail below.

[0026] <Definition of Terms>

[0027] In this specification, the term "refrigerant" includes at least compounds marked with a refrigerant number (ASHRAE number) that begins with R as specified by ISO 817 (International Organization for Standardization) to indicate the type of refrigerant, and also includes substances that, although not marked with a refrigerant number, have the same properties as them as refrigerants.

[0028] From the perspective of compound structure, refrigerants are broadly classified into "fluorocarbon compounds" and "non-fluorocarbon compounds." "Fluorocarbon compounds" include hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). Examples of "non-fluorocarbon compounds" include propane (R290), propylene (R1270), butane (R600), and isobutane (R600a).

[0029] In this specification, the term "composition containing refrigerant" includes at least (1) the refrigerant itself (including refrigerant mixtures); (2) a composition that also contains other components and is capable of being used to obtain a refrigeration working fluid by mixing with at least refrigeration oil; and (3) a refrigeration working fluid containing refrigeration oil.

[0030] In this specification, in all three methods, the composition of (2) is distinguished from the refrigerant itself (including mixtures of refrigerants) and is described as a "refrigerant composition".

[0031] In this specification, the working fluid for refrigeration equipment in (3) is further distinguished from the "refrigerant composition" as "working fluid containing refrigeration oil".

[0032] In this specification, the term "replacement" is used in the context of "replacing" the first refrigerant with the second refrigerant. As a first type, it means that in equipment designed to operate using the first refrigerant, the second refrigerant can be used to operate under optimal conditions as required by only minor changes to components (refrigeration oil, gasket, packing, expansion valve, dryer, at least one of other components) and equipment adjustments.

[0033] In other words, this type refers to "replacing" the refrigerant to make the same equipment work. As for the methods of "replacing" in this type, depending on the degree of change or adjustment required when replacing with a second refrigerant, they can be "direct (drop-in) replacement", "nearly direct (drop-in) replacement" and "retrofit" in order from smallest to largest.

[0034] As a second type, the use of a second refrigerant for the purpose of using equipment designed to operate with a second refrigerant for the same purpose as the existing use of the first refrigerant also falls under the term "substitution." This type refers to "substituting" a refrigerant to provide the same purpose.

[0035] In this specification, the term "refrigerator" refers to any device that reduces the temperature of an object or space to a lower temperature than the surrounding external air and maintains that low temperature by removing heat from the object or space. In other words, a refrigerator is an energy conversion device that converts energy by moving heat from a lower temperature to a higher temperature, obtaining energy from the outside, and performing work.

[0036] In this specification, the terms “containing” and “comprising” include the concepts of “containing,” “including,” “substantially constituted by,” and “consisting solely of.”

[0037] In this specification, when the numerical range is recorded in segments, the upper or lower limit of the numerical range of a certain segment can be arbitrarily combined with the upper or lower limit of the numerical range of other segments.

[0038] In this specification, the upper or lower limits of the numerical ranges described may be replaced with the values ​​shown in the embodiments or values ​​that can be derived without doubt from the embodiments.

[0039] In this specification, the following is stated.

[0040] 2,3,3,3-Tetrafluoropropylene: HFO-1234yf;

[0041] trans-1,2-difluoroethylene: HFO-1132(E)((E)-1,2-difluoroethylene);

[0042] cis-1,2-difluoroethylene: HFO-1132(Z)((Z)-1,2-difluoroethylene);

[0043] (E) and / or (Z)-1,2-difluoroethylene: HFO-1132(E / Z);

[0044] "(E / Z)" means including the E-body (trans-body) and / or the Z-body (cis-body).

[0045] 1,1-Difluoroethylene: HFO-1132a;

[0046] Trifluoroethylene: HFO-1123;

[0047] Tetrafluoroethylene: FO-1114.

[0048] [1] Composition

[0049] (1) Refrigerant

[0050] The compositions of the present invention contain a refrigerant and carbon, wherein the refrigerant comprises at least one compound represented by a molecular formula having one or more carbon-carbon unsaturated bonds.

[0051] In the composition of the present invention, the refrigerant is preferably selected from at least one of 2,3,3,3-tetrafluoropropylene (HFO-1234yf), trans-1,2-difluoroethylene (HFO-1132(E)), cis-1,2-difluoroethylene (HFO-1132(Z)) (the trans and / or cis forms are combined and referred to as HFO-1132(E / Z)), 1,1-difluoroethylene (HFO-1132a), trifluoroethylene (HFO-1123), and tetrafluoroethylene (FO-1114).

[0052] The method of manufacturing the refrigerant to be contained in the composition of the present invention is not particularly limited, and various refrigerants can be manufactured by known manufacturing methods. In the case of HFO-1132(E / Z) as the refrigerant, HFO-1132(E / Z) can be manufactured by dehydrofluorination of 1,1,2-trifluoroethane (HFC-143), hydrogenation of (E) and / or (Z)-1,2-dichloro-1,2-difluoroethylene (CFO-1112(E / Z)), or dehydrochlorination of 1-chloro-1,2-difluoroethane (HCFC-142a).

[0053] The refrigerant content in the composition can be determined by gas chromatography.

[0054] In the compositions of the present invention, the refrigerant content is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more. In the compositions of the present invention, the refrigerant content may also be 99% by mass or more.

[0055] The refrigerant contained in the above composition preferably consists of at least one component selected from HFO-1234yf, HFO-1132(E / Z), HFO-1132a, HFO-1123 and FO-1114.

[0056] The refrigerant contained in the above composition may also contain compounds other than at least one of HFO-1234yf, HFO-1132(E / Z), HFO-1132a, HFO-1123 and FO-1114.

[0057] For example, it may contain impurities that may have been introduced during the manufacture of the refrigerant (unavoidable impurities).

[0058] In the case of, for example, HFO-1132(E / Z), the aforementioned impurities may be hydrogen fluoride, fluoroethylene, HFO-1123, 1,1,1-trifluoroethane, propylene, acetylene, difluoromethane (HFC-32), trifluoromethane, fluoromethane, HFO-1123, 1,1-difluoroethane (HFC-152a), fluoroethane (HFC-161), 1,1,2-trifluoroethane (HFC-143), 2-chloro-1,1,1-trifluoroethane (HCFC-133b), 1-chloro-1,1,2-trifluoroethane (HCFC-133), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), 1-chloro-1,2-difluoroethane (HCFC-142a), 1,2-difluoroethane (HFC-152), chlorine Difluoromethane (HCFC-22), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,2,2-tetrafluoroethane (HFC-134), pentafluoroethane (HFC-125), HFO-1234yf, 1,2,3,3,3-pentafluoropropylene (HFO-1225ye), 1,3,3,3-tetrafluoropropylene (HFO-1234ze), 1,3,3,3-tetrafluoropropylene (HFO-1234ze), fluoroethylene (HFO-1141), 3,3,3-trifluoropropylene (HFO-1243zf), 1,1-difluoroethylene (HFO-1132a), 1-chloro-2,2-difluoroethylene (HCFO-1122), 1-chloro-1,2-difluoroethylene (HCFO-1122a), ethylene, etc.

[0059] When the refrigerant contained in the above composition contains impurities of the refrigerant, the content is not particularly limited, for example, it may contain about 0.1 ppm or more and about 10,000 ppm by weight. Within this range, there are fewer concerns about the stabilizing effect of the refrigerant in the composition being hindered.

[0060] (2) Carbon

[0061] The composition of the present invention contains carbon.

[0062] In the composition of the present invention, it is preferable to contain more than 1 ppm of the above-mentioned carbon by weight relative to the above-mentioned refrigerant.

[0063] In the composition of the present invention, the phrase "containing more than 1 ppm of carbon by weight relative to the refrigerant" means, for example, that when the composition contains a refrigerant, it contains more than 1 mg (more than 1,000,000 parts by weight) of carbon relative to 1 kg of refrigerant.

[0064] In the compositions of the present invention, carbon is a component constituting the composition.

[0065] Because the refrigerants HFO-1234yf, HFO-1132(E / Z), HFO-1132a, HFO-1123, and FO-1114 contain unsaturated bonds, their stability is not good, and they may decompose or oxidize over time, producing acids that could affect the air conditioning cycle. The composition of the present invention, by containing the above-mentioned refrigerants and allowing carbon to coexist, can effectively suppress the decomposition or oxidation of these refrigerants.

[0066] The carbon used is preferably carbon particles. The type of carbon particles is not particularly limited, but is preferably selected from carbon fibers, carbon nanotubes, graphene, graphite (natural graphite particles and artificial graphite particles), and amorphous carbon.

[0067] As for the aforementioned carbon fibers, PAN-based carbon fibers (carbon fibers using acrylic fibers) and pitch-based carbon fibers (carbon fibers using pitch (byproducts of petroleum, coal, coal tar, etc.)) are preferred.

[0068] The preferred carbon nanotubes are single-layer carbon nanotubes, multi-layer carbon nanotubes, and vapor-grown carbon fibers (VGCF).

[0069] The preferred form of graphene is single-layer graphene or multi-layer graphene.

[0070] The preferred form of graphite is natural graphite particles, such as highly thermally conductive flake graphite particles.

[0071] The preferred form of graphite is artificial graphite particles, such as isotropic graphite particles, anisotropic graphite particles, or thermally decomposed graphite particles.

[0072] The preferred amorphous carbon materials are those that are difficult to graphitize, those that are easy to graphitize, carbon black, activated carbon, etc.

[0073] The size of the carbon particles is not particularly limited. When using carbon fibers as carbon particles, short carbon fibers with an average carbon length of 10 μm or more and about 2 mm or less are preferred. When using carbon nanotubes as carbon fibers, carbon nanotubes with an average length of 1 μm or more and about 10 μm or less are preferred. When using graphite (natural graphite particles and / or artificial graphite particles) as carbon fibers, graphite (natural graphite particles and / or artificial graphite particles) with an average length in the longest axis direction of 10 μm or more and about 3 mm or less are preferred.

[0074] When carbon black is used as amorphous carbon, the size of the carbon particles is preferably 10 nm or more.

[0075] In the composition of the present invention, it is preferable to contain 1 ppm or more of carbon by weight relative to the aforementioned refrigerant. By containing carbon, the composition of the present invention can improve the stability of the refrigerant in the composition. In the composition of the present invention, the carbon content relative to the aforementioned refrigerant is more preferably 10 ppm or more by weight, even more preferably 20 ppm or more, particularly preferably 30 ppm or more, and most preferably 40 ppm or more.

[0076] In the composition of the present invention, it is preferable to contain 10,000 ppm or less of carbon by weight relative to the aforementioned refrigerant. By setting the upper limit of the carbon content relative to the aforementioned refrigerant to preferably 10,000 ppm in the composition of the present invention, clogging in equipment such as refrigeration units can be suppressed. In the composition of the present invention, the carbon content relative to the aforementioned refrigerant is preferably 5,000 ppm or less by weight, more preferably 1,000 ppm or less, and even more preferably 500 ppm or less.

[0077] In the composition of the present invention, by adjusting the carbon content relative to the above-mentioned refrigerant to 1 ppm or more and 10,000 ppm or less by weight, the generation of acid components caused by decomposition or oxidation can be suppressed, thereby increasing the stability of the refrigerant.

[0078] In the composition of the present invention, the carbon content relative to the refrigerant can be determined by a commercially available analytical balance, typically with a detection limit of 0.01 ppm by weight. When measured using a commercially available analytical balance (precision balance), the detection limit can be as low as 0.01 mg; for example, when measuring 1 kg of refrigerant in the composition, the detection limit is 0.01 ppm (10 ppb).

[0079] (3) Water

[0080] The composition of the present invention preferably also contains water.

[0081] The compositions of the present invention preferably contain at least 10 ppm of water by weight. The compositions of the present invention preferably contain less than 100 ppm of water by weight.

[0082] In the composition of the present invention, the above-mentioned "containing more than 10 ppm of water by weight" means, for example, that 1 kg of the composition (whole) contains more than 10 mg (more than 1,000,000 parts by weight) of water.

[0083] The compositions of the present invention, by containing water, can improve the stability of the refrigerant in the composition due to the synergistic effect with the presence of carbon. In particular, by adjusting the water content in the composition to 10 ppm or more and 100 ppm or less by weight, the generation of acid components caused by decomposition or oxidation can be suppressed due to the synergistic effect with the presence of carbon, thereby further increasing the stability of the refrigerant.

[0084] In the compositions of the present invention, the water content in the composition, converted to weight, is preferably 10 ppm or more, more preferably 20 ppm or more, even more preferably 30 ppm or more, and particularly preferably 40 ppm or more. The water content in the composition, converted to weight, is preferably 100 ppm or less, more preferably 90 ppm or less, even more preferably 80 ppm or less, and particularly preferably 70 ppm or less.

[0085] In the composition of the present invention, by adjusting the water content, the synergistic effect with the carbon content can be increased, further increasing the stability of the refrigerant and suppressing the generation of acid components, etc.

[0086] In the compositions of the present invention, the water content can be determined using a commercially available Karl Fischer moisture analyzer, typically with a detection limit of 0.1 ppm by weight.

[0087] The composition of the present invention, by containing a refrigerant, carbon, and water, can improve the stability of the refrigerant and also suppress the generation of acid components after long-term storage.

[0088] The reason why water can improve the stability of refrigerants can be attributed to the following mechanism, but a limited explanation is not desired. First, water present in the composition reacts with or stabilizes the fluorinated methyl or fluorinated ethyl radicals generated in the early stages of refrigerant decomposition. As a result, these radicals generated in the early stages of decomposition are less likely to react with the refrigerant, or the reaction rate is reduced. Consequently, a chain reaction is less likely to occur, and oxidation and other reactions become less likely to happen, thus improving the stability of the refrigerant.

[0089] On the other hand, when the water content reaches a certain level (for example, more than 10 ppm by weight), the aforementioned fluorinated methyl radicals or fluorinated ethyl radicals dissolve in the water with the refrigerant, and the concentration locally increases, thus the water becomes the reaction site. As a result, a polymerization reaction of the refrigerant occurs, making the refrigerant easily consumed, thus reducing the stability of the refrigerant, and also producing aggregates caused by the polymerization reaction.

[0090] (4) Other ingredients contained in the composition

[0091] The composition may also contain the refrigerant, carbon, and water, as well as at least one other component. This other component may be, for example, at least one selected from tracers, air, impurities, and byproducts.

[0092] In the above composition, the content of other components is preferably 0.01% by mass or more relative to the total composition. In the above composition, the content of other components is preferably 1% by mass or less relative to the total composition, more preferably 0.1% by mass or less.

[0093] (5) Working fluid containing refrigeration oil

[0094] The composition of the present invention contains the above-mentioned refrigerant and carbon, and may contain water if necessary, and more preferably refrigeration oil, for use as a working fluid (working fluid containing refrigeration oil) in a refrigeration unit.

[0095] The aforementioned working fluid containing refrigeration oil can be specifically obtained by mixing the refrigeration oil used in the compressor of a refrigeration unit with a refrigerant or a combination thereof.

[0096] The composition of the aforementioned working fluid containing refrigeration oil changes during the refrigeration cycle. Specifically, the refrigeration oil content in the working fluid is higher inside the compressor, and lower during the period after it is discharged from the compressor as a mist, circulates in the refrigeration cycle, and returns to the compressor.

[0097] The refrigeration oil content of the working fluid containing refrigeration oil in the compressor is preferably 30% by mass or more and 70% by mass or less.

[0098] The refrigeration oil content of the aforementioned working fluid containing refrigeration oil is preferably 1 ppm or more and 20% by mass or less, more preferably 10% by mass, during the period from discharge from the compressor to return to the compressor.

[0099] The base oil of the aforementioned refrigeration oil is preferably a lubricating oil, but there are no particular limitations. For example, well-known lubricating oils used with refrigerants can be widely used.

[0100] As a specific lubricant, it is preferable to use a lubricating oil selected from at least one of polyalkylene glycol (PAG), polyol ester (POE), and polyvinyl ether (PVE). Examples of polyalkylene glycol (PAG) include "SUNICE P56" manufactured by Japan Sun Oil Co., Ltd. Examples of polyol ester (POE) include "Ze-GLES RB32" manufactured by JX Nippon Oil & Gas Co., Ltd.

[0101] In addition to a base oil, the refrigeration oil preferably contains at least one additive. The additive is preferably selected from at least one component chosen from compatibilizers, ultraviolet fluorescent dyes, stabilizers, polymerization inhibitors, antioxidants, extreme pressure agents, acid scavengers, oxygen scavengers, copper passivators, rust inhibitors, oiliness agents, and defoamers.

[0102] (6) Method for preparing the composition and the working fluid containing refrigeration oil

[0103] There are no particular limitations on the methods for preparing the compositions of the present invention and the working fluid containing refrigeration oil.

[0104] The preferred method for preparing the above composition and the working fluid containing refrigeration oil is to mix the above refrigerant and carbon black, water as needed, and more preferably refrigeration oil, in a predetermined mixing ratio. Other additives may also be appropriately added to this mixture.

[0105] When manufacturing the refrigerant used in conjunction with the composition of the present invention and the working fluid containing refrigeration oil, water is sometimes present in the refrigerant. In the case of preparing the composition of the present invention from such a refrigerant, it is possible to prepare the composition by (1) mixing water with the refrigerant after adding carbon, (2) maintaining the amount of water, or (3) reducing the amount of water. There are no particular limitations on the method for reducing the amount of water in the composition; known methods can be widely used, and a drying method using an adsorbent is preferred.

[0106] When manufacturing the refrigerant used in the composition of the present invention, impurities are sometimes present in the refrigerant. These impurities can be removed beforehand by appropriate methods before preparing the composition, or they can be used directly in the composition without removing the impurities.

[0107] [2] Methods for stabilizing the composition

[0108] The present invention includes a method for stabilizing a refrigerant-containing composition.

[0109] The method for stabilizing a refrigerant-containing composition according to the present invention includes a step of making the composition contain carbon, wherein the refrigerant is a component comprising at least one compound having a molecular formula representing one or more carbon-carbon unsaturated bonds.

[0110] In the method for stabilizing a refrigerant-containing composition according to the present invention, the refrigerant is preferably selected from at least one of HFO-1234yf, HFO-1132(E / Z), HFO-1132a, HFO-1123 and FO-1114.

[0111] Regarding the carbon content mentioned above, it is preferable that the carbon content, calculated by weight, is 1 ppm or more relative to the refrigerant mentioned above.

[0112] According to the method for stabilizing a refrigerant-containing composition of the present invention, at least one component selected from HFO-1234yf, HFO-1132(E / Z), HFO-1132a, HFO-1123 and FO-1114, which is a refrigerant, coexists with carbon, thereby effectively inhibiting the decomposition and oxidation of the refrigerant and improving the stability of the refrigerant.

[0113] The method of the present invention preferably includes a step of further containing water in the composition. Regarding the water content, it is preferable that the water content in the composition is 10 ppm or more by weight.

[0114] According to the method for stabilizing a refrigerant-containing composition of the present invention, the stability of the refrigerant is improved because the water present in the composition makes it difficult for a chain reaction of refrigerant decomposition to occur, and also makes it difficult for oxidation to occur.

[0115] The preferred method of the present invention for stabilizing a refrigerant-containing composition is to further contain refrigeration oil in the composition, thereby stabilizing the working fluid containing refrigeration oil.

[0116] Regarding the refrigerant, refrigeration oil, and other components used in the method for stabilizing the composition of the present invention, the components described in the above-described composition and thermal cycle system items can be used.

[0117] Example

[0118] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0119] (1) Preparation of the composition

[0120] Trans-1,2-difluoroethylene (HFO-1132(E)) is prepared by dehydrofluorination of 1,1,2-trifluoroethane (HFC-143).

[0121] Trifluoroethylene (HFO-1123) is prepared by hydrogen reduction of chlorotrifluoroethylene.

[0122] By adding carbon black and water to the above-mentioned anhydrous refrigerant, a composition containing refrigerant (HFO-1132(E) or HFO-1123), carbon (containing 1 ppm by weight relative to the refrigerant) and water (containing 10 ppm by weight in the composition) is prepared.

[0123] The examples are compositions containing refrigerant and carbon.

[0124] The comparative example is a composition containing a refrigerant but not carbon.

[0125] (2) Methods of stability testing

[0126] For each of the compositions obtained in the Examples and Comparative Examples, stability tests were performed as described below.

[0127] The composition was added to a glass tube (ID8mmΦ×OD12mmΦ×L300mm) that had been fused together on one side, with a refrigerant content of 0.01 mol / L. The tube was then sealed by fusion sealing. The tube was placed in a thermostatic bath at 175°C for 2 weeks. It was then removed from the thermostatic bath and cooled. The stability of the composition was evaluated by analyzing the acid content in the gas inside the tube.

[0128] In the stability test of refrigerant, the acid components in the gas are analyzed by the following method.

[0129] After cooling, the remaining gas in the tube was completely condensed using liquid nitrogen. The tube was then opened and slowly thawed, allowing the gas to be recovered into a Tedra sampling bag. 5g of pure water was injected into the Tedra sampling bag to ensure sufficient contact with the recovered gas, thereby extracting the acid components into the pure water. The extract was analyzed by ion chromatography to determine fluoride ions (F...). － The content (mass ppm) of ).

[0130] (3) Results of stability test

[0131] Table 1 shows the results of the refrigerant stability test.

[0132] [Table 1]

[0133]

[0134] In the compositions of Examples 1-4, the generation of acid components was suppressed by coexisting the refrigerant with carbon, and the refrigerant was evaluated as stable. In particular, even when the compositions of Examples 2 and 4 contained water, the generation of acid components was further suppressed by coexisting the refrigerant with carbon, and the refrigerant was evaluated as even more stable.

[0135] The compositions of Examples 1-4 were evaluated as having refrigerants that are difficult to decompose.

[0136] In the compositions of Comparative Examples 1 and 2, the refrigerant was not present with carbon, thus producing a large amount of acid, which can be evaluated as refrigerant decomposition.

[0137] Although the compositions of Reference Examples 1 and 2 contain water, the refrigerant does not coexist with carbon, thus producing acid components, and can be evaluated as refrigerant being easily decomposed.

[0138] According to the results of stability tests, refrigerants such as HFO-1132(E) and HFO-1123 can be stabilized by having the refrigerant coexist with carbon in the composition.

[0139] Therefore, the composition containing refrigerant and carbon in the above embodiments preferably further contains refrigeration oil, and can be used as a working fluid (working fluid containing refrigeration oil) in a refrigeration unit containing the composition and refrigeration oil.

Claims

1. A composition containing a refrigerant and carbon, characterized in that: The refrigerant comprises at least one selected from trans-1,2-difluoroethylene (HFO-1132(E)), cis-1,2-difluoroethylene (HFO-1132(Z)), 1,1-difluoroethylene (HFO-1132a), trifluoroethylene (HFO-1123), and tetrafluoroethylene (FO-1114). The carbon is carbon particles selected from at least one of carbon fiber, carbon nanotubes, graphene, graphite and amorphous carbon.

2. The composition according to claim 1, characterized in that: The refrigerant contains more than 1 ppm of carbon by weight.

3. The composition according to claim 1 or 2, characterized in that: The composition also contains water at a concentration of 10 ppm to 100 ppm by weight.

4. The composition according to claim 1 or 2, characterized in that: The composition also contains refrigeration oil, and the composition is used as a working fluid containing refrigeration oil.

5. The composition according to claim 3, characterized in that: The composition also contains refrigeration oil, and the composition is used as a working fluid containing refrigeration oil.

6. A method for stabilizing a refrigerant-containing composition, characterized in that: The method includes a step of containing carbon in the composition. The refrigerant comprises at least one selected from trans-1,2-difluoroethylene (HFO-1132(E)), cis-1,2-difluoroethylene (HFO-1132(Z)), 1,1-difluoroethylene (HFO-1132a), trifluoroethylene (HFO-1123), and tetrafluoroethylene (FO-1114). The carbon is carbon particles selected from at least one of carbon fiber, carbon nanotubes, graphene, graphite and amorphous carbon.

7. The method of claim 6, wherein, include: The process containing more than 1 ppm of carbon by weight relative to the refrigerant.

8. The method of claim 6 or 7, wherein, include: A further step is to make the composition contain water at a concentration of 10 ppm or more and 100 ppm or less by weight.

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