FR3082517A1 - STABILIZATION OF 1,1,1,1,4,4,4-HEXAFLUOROBUT-2-ENE - Google Patents

Abstract

The invention relates to the use of a C3 to C6 alkene compound and comprising a single double bond, for limiting or preventing the isomerization of cis-1,1,1,4,4,4-hexafluorobut-2-ene into trans-1,1,1,4,4,4-hexafluorobut-2-ene, or to limit or prevent the degradation of cis-1,1,1,4,4,4-hexafluorobut -2-ene. The invention also relates to a composition comprising at least 50% by weight of 1,1,1,4,4,4-hexafluorobut-2-ene and a C3 to C6 alkene compound and comprising a single double bond; as well as various uses of this composition.

Description

FIELD OF THE INVENTION

The present invention relates to compounds for stabilizing the

1,1,1,4,4,4-hexafluorobut-2-ene and more precisely to limit or prevent the isomerization of the cis form into trans form, or the degradation of the compound. The invention also relates to the use of such stabilizers in heat transfer applications.

TECHNICAL BACKGROUND

Cis-1,1,1,4,4,4-hexafluorobut-2-ene (HFO-1336mzzZ) is a product with a low global warming potential (GWP). It has very favorable thermodynamic and thermophysical properties for use as a heat transfer fluid in cooling, air conditioning, electricity production (notably by organic Rankine cycles) and high temperature heat pumps .

The article “HFO-1336mzz-Z: High Temperature Chemical Stability and Use as A Working Fluid in Organic Rankine Cycles” (2014, K. Kontomahs, International Refrigeration and Air Conditioning Conference, paper 1525) focuses on the properties of HFO- 1336mzzZ and describes it as relatively stable in the presence of metals. The stability of HFO-1336mzzZ alone, in the absence of metallic or other compounds, has not been studied.

Document WO 2009/003165 describes the risks of degradation of hydrofluoroolefins and hydrochlorofluoroolefins, as well as stabilizers making it possible to combat this degradation. These stabilizers include free radical scavenging compounds, acid scavenging compounds, oxygen scavenging compounds and polymerization inhibitors. In particular, the following are cited: 1,2-epoxybutane, glycidyl methyl ether, d-limonene oxide, 1,2-epoxymethylpropane, nitromethane, alpha methylstyrene, isoprene, phenol, hydroquinones and l hydrazine.

Almost all of the stabilizers proposed in the prior art are solid products, or liquid products having a high boiling temperature. For example, the boiling temperature of alphamethylstyrene is 165 ° C, the boiling temperature of limonene oxide is above 200 ° C, etc.

Isoprene, mentioned in document WO 2009/003165, is itself an unstable product in itself, which must generally be combined with a compound such as 4-tert-butylpyrocatechol to avoid its polymerization.

The characteristics described above make the stabilizers unsuitable for certain applications. This is in particular the case of applications using submerged exchangers (in particular with compressors or turbines without lubricating oil). In such applications, the stabilizers of the state of the art, at high boiling temperature, are ineffective, because they concentrate in the evaporator and do not migrate with the heat transfer fluid to the condenser and in the various parts of the circuit.

Furthermore, document WO 2016/146940 describes the use of C3-C6 alkenes compounds for the stabilization of 1-chloro-3,3,3trifluoropropene.

It was found by the present inventors that HFO-1336mzzZ has an instability which manifests itself above all at relatively high temperature. This instability consists of an isomerization of a fraction of the initial charge resulting in the formation of trans-1,1,1,4,4,4-hexafluorobut-2ene (HFO-1336mzzE) as well as in the degradation of the compound.

Both the isomerization and the degradation of the compound involve a change in the thermodynamic and thermophysical properties of the product in the installations, and a loss of performance.

There is therefore a need to stabilize the HFO-1336mzzZ, in particular in vapor compression systems such as air conditioning, refrigeration, heat pump and organic Rankine cycle systems, in particular systems comprising a flooded evaporator, and especially in high temperature applications.

SUMMARY OF THE INVENTION

The invention relates firstly to the use of a C3 to C6 alkene compound and comprising a single double bond, to limit or prevent the isomerization of cis-1,1,1,4,4,4-hexafluorobut- 2-ene in trans-1,1,1,4,4,43 hexafluorobut-2-ene, or to limit or prevent the degradation of cis-

1,1,1,4,4,4-hexafluorobut-2-ene.

In certain embodiments, the alkene compound is a butene or a pentene.

In certain embodiments, the alkene compound has:

- a boiling point less than or equal to 100 ° C, preferably less than or equal to 75 ° C, and more particularly preferably less than or equal to 50 ° C; and or

- A solidification temperature less than or equal to 0 ° C, preferably less than or equal to -25 ° C, and more particularly preferably less than or equal to -50 ° C.

In certain embodiments, the alkene compound is 2-methylbut-2-ene.

In certain embodiments, the alkene compound is 3-methylbut-1-ene.

The subject of the invention is also a composition comprising at least 50% by weight of 1,1,1,4,4,4-hexafluorobut-2-ene, and a C3 to C6 alkene compound and comprising a single double bond.

In certain embodiments, the alkene compound is a butene or a pentene.

In certain embodiments, the alkene compound has:

- a boiling point less than or equal to 100 ° C, preferably less than or equal to 75 ° C, and more particularly preferably less than or equal to 50 ° C; and or

- A solidification temperature less than or equal to 0 ° C, preferably less than or equal to -25 ° C, and more particularly preferably less than or equal to -50 ° C.

In certain embodiments, the alkene compound is 2-methylbut-2-ene.

In certain embodiments, the alkene compound is 3-methylbut-1-ene.

In certain embodiments, the composition comprises from 0.01 to 5%, preferably from 0.1 to 2%, and more particularly from 0.2 to 1%, by mass, of alkene compound.

In certain embodiments, 1,1,1,4,4,4-hexafluorobut-2-ene is in cis form in a mass proportion greater than or equal to 90%, preferably greater than or equal to 95%, so more particularly preferred greater than or equal to 98%, even more particularly preferably greater than or equal to 99%, and ideally greater than or equal to 99.5% or even greater than or equal to 99.9%.

In some embodiments, the composition further comprises one or more heat transfer compounds other than the

1,1,1,4,4,4-hexafluorobut-2-ene and / or one or more additives chosen from stabilizers other than the alkene compound, lubricants, surfactants, tracer agents, fluorescent agents, odorous agents , solubilizers and mixtures thereof.

The invention also relates to the use of the above composition as a heat transfer fluid in a vapor compression system.

In some embodiments, the vapor compression system is:

- an air conditioning system; or

- a refrigeration system; or

- a freezing system; or

- a heat pump system.

In some embodiments, the above use is use as a heat transfer fluid in a heat engine.

In certain embodiments, the heat transfer fluid is at a temperature greater than or equal to 100 ° C., preferably greater than or equal to 140 ° C., preferably greater than or equal to 180 ° C., preferably greater than or equal to 200 ° C, more preferably greater than or equal to 240 ° C, and more particularly preferably greater than or equal to 270 ° C, for at least a fraction of its duration of use.

In some embodiments, the heat transfer fluid is evaporated in a flooded evaporator.

The invention also relates to a heat transfer installation comprising a circuit containing the above composition as a heat transfer fluid.

In certain embodiments, the installation is chosen from mobile or stationary installations for heating by heat pump, air conditioning, refrigeration, freezing, thermodynamic cycles of electricity production of organic Rankine cycle type and motors. thermal.

In some embodiments, the installation includes a flooded evaporator.

The invention also relates to a method of heating or cooling a fluid or a body by means of a vapor compression system containing a heat transfer fluid, said method successively comprising the evaporation of the fluid heat transfer medium, compression of the heat transfer medium, condensation of the heat transfer medium and expansion of the heat transfer medium, in which the heat transfer medium is the composition described above.

The invention also relates to a method of producing electricity by means of a heat engine, said method successively comprising the evaporation of the heat transfer fluid, the expansion of the heat transfer fluid in a turbine making it possible to generate electricity, the condensation of the heat transfer fluid and the compression of the heat transfer fluid, in which the heat transfer fluid is the composition described above.

The present invention meets the need expressed above. It more particularly provides a means for stabilizing the HFO-1336mzzZ, so as to avoid the problems of isomerization and degradation which have been observed by the inventors, in particular in vapor compression systems such as air conditioning systems, refrigeration, heat pump and heat engine, especially systems with a flooded evaporator, and especially in high temperature applications.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention is now described in more detail and without limitation in the description which follows.

Unless otherwise stated, throughout the application the proportions of compounds indicated are given in percentages by mass.

The invention is based on the discovery that the C3 to C6 alkenes compounds comprising a single double bond make it possible to stabilize HFO-1336mzzZ, that is to say to limit or prevent its isomerization into HFO-1336mzzE, in particular to high temperatures. The presence of this type of compound also makes it possible to stabilize HFO-1336mzzZ while avoiding its degradation. By "degradation" is meant the conversion of molecules of

HFO-1336mzz in other species. The degradation of HFO-1336mzzZ can in particular result in an increase in the concentration of fluoride ions present in the composition comprising HFO-1336mzzZ.

The stabilizing compounds of the invention are therefore propene, butenes, pentenes and hexenes. Butenes and pentenes are preferred. Pentenes are even more particularly preferred.

The stabilizing compounds of the invention may be straight or branched chain, and preferably branched.

Preferably, they have a boiling point less than or equal to 100 ° C, more preferably less than or equal to 75 ° C, and more particularly preferably less than or equal to 50 ° C.

By "boiling temperature" is meant the boiling temperature at a pressure of 101.325 kPa, as determined according to standard NF EN 378-1 of April 2008.

Also preferably, they have a solidification temperature less than or equal to 0 ° C, preferably less than or equal to -25 ° C, and more particularly preferably less than or equal to -50 ° C.

The solidification temperature is determined according to Test No. 102: Melting point / melting range (OECD Guidelines for the Testing of Chemicals, Section 1, OECD Publishing, Paris, 1995, available at http://dx.doi.Org/10.1787/9789264069534-fr).

Stabilizing compounds of the invention are in particular:

- but-1-ene;

- cis-but-2-ene;

- trans-but-2-ene;

- 2-methyl-prop-1-ene;

- pent-1-ene;

- cis-pent-2-ene;

- trans-pent-2-ene;

- 2-methyl-but-1-ene;

- 2-methyl-but-2-ene; and

- 3-methyl-but-1-ene.

Among the preferred compounds, there is in particular 2-methyl-but-2ene, of formula (CH3) 2C = CH-CH3 (boiling point of approximately 39 ° C.).

Two or more than two of the above compounds can also be used in combination.

The stabilizing compounds according to the invention are thus advantageously used in combination with HFO-1336mzz, and more particularly with HFO-1336mzzZ, in heat transfer applications.

Thus, the invention provides a composition, especially useful for heat transfer applications, comprising at least HFO-1336mzz (in a weight content of at least 50%) and a stabilizing compound described above.

The mass proportion of the above stabilizing compounds in the composition can in particular be: from 0.01 to 0.05%; or from 0.05 to 0.1%; or from 0.1 to 0.2%, or from 0.2 to 0.3%; or from 0.3 to 0.4%; or from 0.4 to 0.5%; or from 0.5 to 0.6%; or from 0.6 to 0.7%; or from 0.7 to 0.8%; or from 0.8 to 0.9%; or from 0.9 to 1%; or from 1 to 1.2%; or from 1.2 to 1.5%, or from 1.5 to 2%; or from 2 to%; or from 3 to 4%; or 4 to 5%.

The composition can include HFO-1336mzzZ and possibly HFO-1336mzzE. Advantageously, the proportion of HFO-1336mzzZ, relative to the total of HFO-1336mzz, is greater than or equal to 90%, or to 91%, or to 92%, or to 93%, or to 94%, or to 95% , or 96%, or 97%, or 98%, or 99%, or 99.1%, or 99.2%, or 99.3%, or 99.4%, or 99.5%, or 99.6%, or 99.7%, or 99.8%, or 99.9%, or 99.91%, or 99.92%, or 99.93%, or 99.94%, or 99.95%, or 99.96%, or 99.97%, or 99.98%, or 99.99%.

The presence of the stabilizing compound makes it possible to limit or prevent an increase in the proportion of HFO-1336mzzE in the composition over time and / or when relatively high temperatures are applied. The presence of the stabilizing compound also makes it possible to limit the concentration of fluoride ions present in the composition and more generally to limit the degradation of HFO-1336mzzZ.

In addition, the stabilizing compound in question is likely to also have a heat transfer function, like HFO-1336mzzZ and other possible heat transfer compounds. In certain embodiments, it is capable of forming azeotropic or quasi-azeotropic mixtures with HFO-1336mzzZ (and if necessary with the other heat transfer compounds that may be present).

The composition of the invention may also contain various additives. In the case where it is a heat transfer composition, the additives can in particular be chosen from lubricants, nanoparticles, stabilizers (different from the stabilizing compounds of the invention), surfactants, tracer agents, fluorescent agents, odorants and solubilizers.

The stabilizer or stabilizers, when they are present, preferably represent at most 5% by mass in the heat transfer composition. Among the stabilizers, mention may in particular be made of nitromethane, ascorbic acid, terephthalic acid, azoles such as toluthazole or benzotriazole, phenolic compounds such as tocopherol, hydroquinone, t-butyl hydroquinone, 2,6-di-ter-butyl-4-methylphenol, epoxides (optionally fluorinated or perfluorinated or alkenyl or aromatic alkyl) such as n-butyl glycidyl ether, hexanediol diglycidyl ether, allyl glycidyl ether, butylphenylglycidyl ether, phosphites, phosphonates, thiols and lactones.

As lubricants, it is possible in particular to use oils of mineral origin, silicone oils, paraffins of natural origin, naphthenes, synthetic paraffins, alkylbenzenes, poly-alpha olefins, polyalkene glycols, polyol esters. and / or polyvinyl ethers.

In certain advantageous embodiments of the invention, the composition of the invention is however devoid of lubricant.

As nanoparticles, it is possible in particular to use carbon nanoparticles, metal oxides (copper, aluminum), T1O2, AI2O3, M0S2 ...

As tracer agents (capable of being detected), mention may be made of hydrofluorocarbons, deuterated or not, deuterated hydrocarbons, perfluorocarbons, fluoroethers, brominated compounds, iodized compounds, alcohols, aldehydes, ketones, nitrous oxide and combinations thereof. The tracer is different from the heat transfer compound (s) making up the heat transfer fluid.

As solubilizers, mention may be made of hydrocarbons, dimethyl ether, polyoxyalkylene ethers, amides, ketones, nitriles, chlorocarbons, esters, lactones, aryl ethers, fluoroethers and 1.1 , 1-trifluoroalcanes. The solubilizer is different from the heat transfer compound (s) making up the heat transfer fluid.

As fluorescent agents, there may be mentioned naphthalimides, perylenes, coumarins, anthracenes, phenanthracenes, xanthenes, thioxanthenes, naphthoxanhtenes, fluoresceins and derivatives and combinations thereof.

As odorants, mention may be made of alkylacrylates, allylacrylates, acrylic acids, acrylesters, alkyl ethers, alkyl esters, alkynes, aldehydes, thiols, thioethers, disulfides, allylisothiocyanates, alkanoic acids , amines, norbornenes, norbornene derivatives, cyclohexene, heterocyclic aromatics, ascaridole, o-methoxy (methyl) -phenol and combinations thereof.

The composition according to the invention can also comprise at least one other heat transfer compound, in addition to HFO-1336mzz. Such another optional heat transfer compound may in particular be a hydrocarbon, ether, hydrofluoroether, hydrofluorocarbon, hydrochlorofluorocarbon, hydrofluoroolefin, hydrochloroolefin or hydrochlorofluoroolefin compound.

By way of example, said other heat transfer compound can be chosen from 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd, E or Z isomer), 3,3,4,4,4 -pentafluorobut-1-ene (HFO-1345fz), 2,4,4,4-tetrafluorobut-1-ene (HFO-1354mfy), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,3,3,3-tetrafluoropropene (HFO-1234ze), difluoromethane (HFC-32), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1-difluoroethane (HFC-152a), pentafluoroethane (HFC-125), 1,1,1,3 , 3-pentafluorobutane (HFC-365mfc), methoxynonafluorobutane (HFE7100), butane (HC-600), 2-methylbutane (HC-601a), pentane (HC-601), ethyl ether, methyl acetate and combinations thereof.

In the composition of the invention, the HFO-1336mzz can represent in particular from 50 to 55% of the composition; or from 55 to 60% of the composition; or from 60 to 65% of the composition; or from 65 to 70% of the composition; or from 70 to 75% of the composition; or from 75 to 80% of the composition; or from 80 to 85% of the composition; or from 85 to 90% of the composition; or from 90 to 95% of the composition;

or from 95 to 99% of the composition; or from 99 to 99.5% of the composition; or from 99.5 to 99.9% of the composition; or more than 99.9% of the composition. The content of HFO-1336mzz can also vary in several of the above ranges: for example from to 55% and from 55 to 60%, i.e. from 50 to 60%, etc.

The composition of the invention can be used in a heat transfer process.

The heat transfer method according to the invention is based on the use of an installation comprising a vapor compression system which contains the composition of the invention as a heat transfer fluid. The heat transfer process can be a process of heating or cooling a fluid or a body.

The composition of the invention can also be used in a process for the production of mechanical work or electricity, in particular in accordance with a Rankine cycle.

For heating and cooling applications, the vapor compression system includes at least one evaporator, compressor, condenser and expansion valve, as well as heat transfer fluid transport lines between these elements. The evaporator and the condenser include a heat exchanger allowing a heat exchange between the heat transfer fluid and another fluid or body.

As a compressor, it is possible in particular to use a centrifugal compressor with one or more stages or a centrifugal mini-compressor. Rotary, scroll, piston or screw compressors can also be used. The compressor can be driven by an electric motor or by a gas turbine (for example powered by vehicle exhaust gases, for mobile applications) or by gear.

The vapor compression system then operates according to a conventional vapor compression cycle. The cycle includes changing the state of the heat transfer fluid from a liquid phase (or two-phase liquid / vapor) to a vapor phase at a relatively low pressure, then compressing the fluid in the vapor phase to a relatively low pressure. high, the change of state (condensation) of the heat transfer fluid from the vapor phase to the liquid phase at a relatively high pressure, and the reduction of the pressure to start the cycle again.

The installation can also optionally include at least one heat transfer fluid circuit used to transmit heat (with or without change of state) between the heat transfer fluid circuit and the fluid or body to be heated or cooled.

The installation can also optionally include two (or more) vapor compression systems, containing identical or distinct heat transfer fluids. For example, vapor compression systems can be coupled together.

The cooling methods and installations according to the invention include the methods and installations for air conditioning (with mobile installations, for example in vehicles, or stationary), refrigeration (with mobile installations for example in containers, or stationary) and freezing or cryogenics.

The heating installations according to the invention include heat pumps.

For mechanical work or electricity production applications, the installation is a heat engine, which includes at least one evaporator, an expansion device, a condenser and a pump, as well as lines for transporting transfer fluid from heat between these elements. The installation can then operate on a Rankine cycle.

As an expansion device, it is possible in particular to use turbines with one or more stages or regulators. For example, rotary, spiral, piston or screw regulators can also be used.

It is possible to use any type of heat exchanger for implementing the heat transfer fluids according to the invention, and in particular co-current heat exchangers or, preferably, counter heat exchangers. -current.

In particular, the evaporator used in the context of the invention can be an overheated evaporator or a flooded evaporator. In an overheated evaporator, all of the heat transfer fluid is evaporated at the outlet of the evaporator, and the vapor phase is overheated.

In a flooded evaporator, the heat transfer fluid in liquid form does not evaporate completely. A flooded evaporator has a liquid phase and vapor phase separator.

The invention is particularly useful when such an evaporator is used. Indeed, the stabilizers of the state of the art at high boiling temperature are ineffective when such an evaporator is used, because they concentrate in the evaporator and do not migrate with the heat transfer fluid to the condenser.

The invention is also particularly useful when a high temperature exists at at least one point in the fluid circuit, and more particularly a temperature greater than or equal to 100 ° C, or 110 ° C, or 120 ° C, or

130 ° C, or 140 ° C, or 150 ° C, or 160 ° C, or 170 ° C, or 180 ° C, or

190 ° C, or 200 ° C, or 210 ° C, or 220 ° C, or 230 ° C, or 240 ° C, or

250 ° C, or 260 ° C, or 270 ° C. In fact, it is under these conditions that

HFO-1336mmzZ is most likely to convert to HFO-1336mmzE or to degrade.

In particular, in air conditioning equipment, the general operating temperature is less than 100 ° C; but hot spots at the outlet of the compressor can reach temperatures above 100 ° C, affecting the heat transfer fluid for a small proportion of its complete circulation time (for example less than 1%).

In heat pumps, the condensing temperature can reach approximately 165 ° C. In this case, the heat transfer fluid can be at a temperature of approximately 165 ° C. over a significant proportion of its complete circulation time (for example approximately 50%). In addition, hot spots between 180 and 200 ° C can also be observed at the outlet of the compressor. The impact of a long residence time at temperatures above 100 ° C and the existence of points at temperatures which may approach or even exceed 200 ° C therefore require a stabilizer.

In engine cycles for the production of Rankine organic cycle type electricity, the temperature can reach 165 ° C. In this case, the heat transfer fluid may be at a temperature of approximately 165 ° C. or more over a significant proportion of its complete circulation time (for example approximately 50%). In addition, hot spots between 180 and 250 ° C, or more than 250 ° C, can also be observed at the inlet of the turbine. The impact of a long residence time at temperatures above 100 ° C and the existence of points at temperatures which may approach or even exceed 250 ° C therefore require a stabilizer.

Also preferably, in the installation according to the invention, the temperature of the composition used as heat transfer fluid remains higher than the solidification temperature of the stabilizing compound, in order to avoid any deposit of solid material in the circuit. .

The composition according to the invention can also be useful as a blowing agent, propellant (for example for an aerosol), cleaning agent or solvent, dielectric gas, in addition to its use as a heat transfer fluid. .

As a propellant, the composition according to the invention can be used alone or in combination with known propellants. The propellant comprises, preferably consists of, a composition according to the invention. The active substance to be sprayed can be mixed with the propellant and inert compounds, solvents or other additives, to form a spray composition. Preferably, the composition to be sprayed is an aerosol.

As blowing agent, the composition according to the invention can be included in a blowing composition, which preferably comprises one or more other compounds capable of reacting and of forming a foam or cellular structure under appropriate conditions, as is known to those skilled in the art.

In particular, the invention provides a process for the preparation of an expanded thermoplastic product first comprising the preparation of a polymeric expansion composition. Typically, the polymeric expanding composition is prepared by plasticizing a polymeric resin and mixing the compounds of a blowing agent composition at an initial pressure. The plasticization of the polymeric resin can be done under the effect of heat, by heating the polymeric resin to soften it enough to mix a blowing agent composition. Generally, the plasticization temperature is close to the glass transition temperature or the melting temperature for crystalline polymers.

Other uses of the composition according to the invention include uses as a solvent, cleaning agent or the like. Examples include degreasing by steam, precision cleaning, cleaning of electronic circuits, dry cleaning, abrasive cleaning, solvents for depositing lubricants and release agents, and other treatments. solvent or surface.

EXAMPLES

The following examples illustrate the invention without limiting it.

Example 1 - stabilization of the HFO-1336mzzZ

The thermal stability tests of the HFO-1336mzzZ are carried out according to the ASHRAE 97-2007 standard entitled "Sealed glass tube method to test the chemical stability of materials for use within refrigerant systems".

The compositions are determined by gas chromatography with an FID detector and on a CP-sil8-CB column (50m * 0.32mm * 5pm). The oven temperature is 40 ° C for 10 minutes, then 8 ° C per minute up to 250 ° C.

A first series of tests is carried out with HFO-1336mzzZ in the absence of stabilizer, at 220 ° C for 14 days. The results show the formation of the HFO-1336mzzE isomer at a mass content of 1.85% on average.

A second series of tests is carried out with HFO-1336mzzZ in the presence of 0.5% of 2-methyl-but-2-ene as stabilizer (mass content relative to the sum of the stabilizer and HFO-1336mzzZ) at 220 ° C for 14 days. The results show a formation of the HFO-1336mzzE isomer at a mass content of only 0.75% on average.

Thus, the use of 2-methyl-but-2-ene as stabilizer has made it possible to stabilize HFO-1336mzzZ by reducing its isomerization by about 60%.

Example 2 - stabilization of the HFO-1336mzzZ

A first series of tests is carried out with HFO-1336mzzZ in the absence of stabilizer, at 220 ° C for 14 days. The results show the presence of fluoride ions in the sample at a concentration of 92.5 ppm on average.

A second series of tests is carried out with HFO-1336mzzZ in the presence of 0.5% of 2-methyl-but-2-ene as stabilizer (mass content relative to the sum of the stabilizer and HFO-1336mzzZ) at 220 ° C for 14 days. The results show the presence of fluoride ions in the sample at a concentration of only 5 ppm on average.

Thus, the use of 2-methyl-but-2-ene as stabilizer allowed the stabilization of HFO-1336mzzZ by reducing the concentration of fluoride ions in the samples and therefore the degradation of the compound.

Claims (21)

1. Use of a C3 to C6 alkene compound having a single double bond, to limit or prevent the isomerization of cis-1,1,1,4,4,4-hexafluorobut-2-ene in trans-1 , 1,1,4,4,4hexafluorobut-2-ene, or to limit or prevent the degradation of cis-1,1,1,4,4,4-hexafluorobut-2-ene. 2. Use according to claim 1, wherein the alkene compound is a butene or a pentene. 3. Use according to claim 1 or 2, in which the alkene compound has: - a boiling point less than or equal to 100 ° C, preferably less than or equal to 75 ° C, and more particularly preferably less than or equal to 50 ° C; and or - A solidification temperature less than or equal to 0 ° C, preferably less than or equal to -25 ° C, and more particularly preferably less than or equal to -50 ° C. 4. Use according to one of claims 1 to 3, wherein the alkene compound is 2-methyl-but-2-ene. 5. Composition comprising at least 50% by weight of 1,1,1,4,4,4hexafluorobut-2-ene, and a C3 to C6 alkene compound and comprising a single double bond. 6. Composition according to claim 5, in which the alkene compound is a butene or a pentene. 7. Composition according to claim 5 or 6, in which the alkene compound has: - a boiling point less than or equal to 100 ° C, preferably less than or equal to 75 ° C, and more particularly preferably less than or equal to 50 ° C; and or - A solidification temperature less than or equal to 0 ° C, preferably less than or equal to -25 ° C, and more particularly preferably less than or equal to -50 ° C. 8. Composition according to one of claims 5 to 7, in which the alkene compound is 2-methyl-but-2-ene. 9. Composition according to one of claims 5 to 8, comprising from 0.01 to 5%, preferably from 0.1 to 2%, and more particularly from 0.2 to 1%, by mass, of alkene compound. 10. Composition according to one of claims 5 to 9, in which the 1,1,1,4,4,4-hexafluorobut-2-ene is in cis form in a mass proportion greater than or equal to 90%, preferably greater than or equal to 95%, more particularly preferably greater than or equal to 98%, even more particularly preferably greater than or equal to 99%, and ideally greater than or equal to 99.5% or even greater than or equal to 99.9 %. 11. Composition according to one of claims 5 to 10, further comprising one or more heat transfer compounds other than 1,1,1,4,4,4-hexafluorobut-2-ene and / or one or more additives chosen from stabilizers other than the alkene compound, lubricants, surfactants, tracer agents, fluorescent agents, odorants, solubilizers and mixtures thereof. 12. Use of a composition according to one of claims 5 to 11 as a heat transfer fluid in a vapor compression system. 13. Use according to claim 12, in which the vapor compression system is: - an air conditioning system; or - a refrigeration system; or - a freezing system; or - a heat pump system. 14. Use of a composition according to one of claims 5 to 11 as a heat transfer fluid in a heat engine. 15. Use according to one of claims 12 to 14, wherein the heat transfer fluid is at a temperature greater than or equal to 100 ° C, preferably greater than or equal to 140 ° C, preferably greater than or equal to 180 ° C, preferably greater than or equal to 200 ° C, more preferably greater than or equal to 240 ° C, and more particularly preferably greater than or equal to 270 ° C, for at least a fraction of its duration of use. 16. Use according to one of claims 12 to 15, in which the heat transfer fluid is evaporated in a flooded evaporator. 17. Heat transfer installation comprising a circuit containing a composition according to one of claims 5 to 11 as a heat transfer fluid. 18. Installation according to claim 17, chosen from mobile or stationary installations for heating by heat pump, air conditioning, refrigeration, freezing, thermodynamic cycles for producing electricity of the organic Rankine cycle type and heat engines. 19. Installation according to claim 17 or 18, comprising a flooded evaporator. 20. A method of heating or cooling a fluid or a body by means of a vapor compression system containing a heat transfer fluid, said method successively comprising evaporation of the heat transfer fluid, the compression of the heat transfer fluid, condensation of the heat transfer fluid and expansion of the heat transfer fluid, in which the heat transfer fluid is a composition according to one of claims 5 to 11. 21. Process for producing electricity by means of a motor 5 thermal, said method successively comprising evaporation of the heat transfer fluid, the expansion of the heat transfer fluid in a turbine for generating electricity, the condensation of the heat transfer fluid and the compression of the fluid heat transfer, in which the heat transfer fluid 10 is a composition according to one of claims 5 to 11.