GB2541441A - Composition - Google Patents

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Publication number
GB2541441A
GB2541441A GB1514822.4A GB201514822A GB2541441A GB 2541441 A GB2541441 A GB 2541441A GB 201514822 A GB201514822 A GB 201514822A GB 2541441 A GB2541441 A GB 2541441A
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Prior art keywords
composition
mol
azeotropic
1234zee
process according
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GB1514822.4A
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GB201514822D0 (en
Inventor
Mary Skae Clare
Lloyd Gary
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Mexichem Fluor SA de CV
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Mexichem Fluor SA de CV
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Priority to GB1514822.4A priority Critical patent/GB2541441A/en
Publication of GB201514822D0 publication Critical patent/GB201514822D0/en
Priority to PCT/GB2016/052545 priority patent/WO2017029499A1/en
Publication of GB2541441A publication Critical patent/GB2541441A/en
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
    • B01D3/36—Azeotropic distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/23—Preparation of halogenated hydrocarbons by dehalogenation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/25—Preparation of halogenated hydrocarbons by splitting-off hydrogen halides from halogenated hydrocarbons
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C19/00—Acyclic saturated compounds containing halogen atoms
    • C07C19/08—Acyclic saturated compounds containing halogen atoms containing fluorine
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C21/00—Acyclic unsaturated compounds containing halogen atoms
    • C07C21/02—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds
    • C07C21/18—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds containing fluorine
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
    • C09K5/02—Materials undergoing a change of physical state when used
    • C09K5/04—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa
    • C09K5/041—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa for compression-type refrigeration systems
    • C09K5/044—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa for compression-type refrigeration systems comprising halogenated compounds
    • C09K5/045—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa for compression-type refrigeration systems comprising halogenated compounds containing only fluorine as halogen
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2205/00—Aspects relating to compounds used in compression type refrigeration systems
    • C09K2205/10—Components
    • C09K2205/12—Hydrocarbons
    • C09K2205/126—Unsaturated fluorinated hydrocarbons
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2205/00—Aspects relating to compounds used in compression type refrigeration systems
    • C09K2205/22—All components of a mixture being fluoro compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2205/00—Aspects relating to compounds used in compression type refrigeration systems
    • C09K2205/32—The mixture being azeotropic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2205/00—Aspects relating to compounds used in compression type refrigeration systems
    • C09K2205/40—Replacement mixtures

Abstract

An azeotropic or near-azeotropic composition comprising CH3CF2CF3 (1,1,1,2,2-pentafluoropropane, HFC-245cb) and CHFCHCF3 (trans-1,3,3,3-tetrafluoropropane, 1234zeE). The compositions may further comprise a lubricant, a stabiliser and/or a flame retardant. The compositions may be used in the manufacture of one or more hydrofluoroolefins, preferably CHFCHCF3­ (trans-1,3,3,3-tetrafluoropropane, 1234zeE) or CH2CFCF3 (2,3,3,3-tetrafluoropropene, 1234yf). The composition may be used as a heat transfer composition in various heat transfer devices. The devices may be selected from a mechanical power generation device, a refrigeration device and a air conditioning system. Methods for cooling or heating an article via condensation or evaporation of the composition in the vicinity of an article is also provided. Various methods of use are also disclosed. A process for the separation of the claimed composition is also provided, preferably wherein the process uses pressure swing distillation. A process for preparing CH2CFCF3 (2,3,3,3-tetrafluoropropene, 1234yf) is also provided.

Description

Composition
The present invention relates to azeotropic or near-azeotropic compositions comprising CH3CF2CF3 (245cb) and CHFCHCF3 (1234zeE) along with uses thereof of such compositions particularly in processes for the preparation of CH2CHFCF3 (1234yf). 2,3,3,3-tetrafluoropropene is also known as HFO-1234yf, HFC-1234yf or simply 1234yf. Hereinafter, unless otherwise stated, 2,3,3,3-tetrafluoropropene will be referred to as 1234yf. The known processes for preparing 1234yf typically suffer from disadvantages such as low yields, and/or the handling of toxic and/or expensive reagents, and/or the use of extreme conditions, and/or the production of toxic by-products. Methods for the preparation of 1234yf have been described in, for example, Journal Fluorine Chemistry (82), 1997, 171-174. In this paper, 1234yf is prepared by the reaction of sulphur tetrafluoride with trifluoroacetylacetone. However, this method is only of academic interest because of the hazards involved in handling the reagents and their expense. Another method for the preparation of 1234yf is described in US-2931840. In this case, pyrolysis of C1 chlorofluorocarbons with or without tetrafluoroethylene was purported to yield 1234yf. However, the yields described were very low and again it was necessary to handle hazardous chemicals under extreme conditions. It would also be expected that such a process would produce a variety of very toxic by-products. CHFCHCF3 (or 1234ze), as is 1234yf, is useful as a refrigerant or heat transfer agent as well as a blowing agent or propellant, particularly as a replacement for hydrofluorocarbon (HFC) compounds which despite their low ozone depletion potential have a high global warming potential. 1234yf and 1234ze each have the advantage of low ozone depletion potential and low global warming potential, making them particularly attractive in such applications.
Accordingly, there is a need for a process which is able to produce both 1234yf and 1234ze, which involves the use of widely available feedstocks, produces a commercially acceptable yield and does not produce large quantities of hazardous chemicals which require disposal. The present invention addresses this problem.
The listing or discussion of a prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.
The present invention provides azeotropic or near-azeotropic compositions comprising 245cb and 1234zeE.
Also provided by the invention is the use of such azeotropic or near-azeotropic compositions (e.g. as an intermediate) in the manufacture of one or more hydrofluoroolefins.
Further provided is the use of an azeotropic or near-azeotropic composition of the invention as a heat transfer composition.
Also provided is a process for the separation of an azeotropic or near-azeotropic composition of the invention.
Further provided is a process for the preparation of CH2CFCF3 (1234yf), the process comprising: a) dehydrofluorinating CH3CF2CF3 (245cb) to produce a reaction product comprising 1234yf, CHFCHCF3 (1234ze(E)(Z)) and CF2CH2CF3 (245fa); b) separating 1234yf, 1234ze(Z) and 245fa from the reaction product yielding an azeotropic or near-azeotropic composition of the invention; and c) recycling the azeotropic or near-azeotropic composition of step (b) into step (a).
Compositions of the Invention
In a first aspect, the invention provides an azeotropic or near-azeotropic composition comprising CH3CF2CF3 (245cb) and CHFCHCF3 (1234zeE).
In an embodiment, the azeotropic or near-azeotropic composition of the invention consists essentially of 245cb and 1234zeE. In a further embodiment, the composition consists of 245cb and 1234zeE.
By azeotrope or azeotropic composition, we mean a preferably binary composition which at vapour-liquid equilibrium has the same composition in both the liquid and vapour phase, and whose boiling point is lower than that of either of the pure components. By near-azeotrope or near-azeotropic composition (e.g. a near-azeotropic composition of 245cb and 1234zeE), we mean a composition that behaves similarly to an azeotrope composition (i.e. the composition has constant boiling characteristics or a tendency not to fractionate upon boiling), but may not have all of the properties of an azeotrope, for example binary liquid compositions whose vapour pressure is above that of the pure component with the lower boiling point (e.g. 1234zeE compared to 245cb) when measured at equivalent temperature, but whose equilibrium vapour composition may differ from the liquid composition.
In essence, at a given pressure, a boiling azeotrope or near azeotrope composition has substantially the same constituent proportions in the vapour phase as in the boiling liquid phase. This means that no (or substantially no) fractionation of the components in the liquid composition takes place.
Preferably the azeotropic or near-azeotropic composition of the invention comprises, or preferably consists of, from about 50 mol% to about 98 mol% 1234zeE and from about 50 mol% to about 2 mol% 245cb. Alternatively, the azeotropic or near-azeotropic composition of the invention comprises, or preferably consists of, from about 60 mol% to about 95 mol% 1234zeE and from about 40 mol% to about 5 mol% 245cb, such as about 60 mol% to about 85 mol% 1234zeE and from about 40 mol% to about 15 mol% 245cb, for example about 70 mol% to about 85 mol% 1234zeE and from about 30 mol% to about 15 mol% 245cb, preferably about 70 mol% to about 80 mol% 1234zeE and from about 30 mol% to about 20 mol% 245cb.
In an embodiment, the azeotropic or near-azeotropic composition of the invention is present at temperatures of from about -30°C to about +80°C, such as from about -20°C to about +70°C, for example from about 0°C to about +70°C preferably from temperatures of from about +30°C to about +70°C
In a further embodiment, the azeotropic or near-azeotropic composition of the invention is present at pressures of from about 0.5 bara to about 30 bara, for example from about 10 to about 25 bara, preferably about 15 to about 20 bara.
In a preferred embodiment, the azeotropic or near-azeotropic composition of the invention comprises from about 60 mol% to about 95 mol% 1234zeE and from about 40 mol% to about 5 mol% 245cb, wherein the azeotropic or near-azeotropic composition is present at temperatures of between about -20°C to about +70°C and pressures of between about 0.9 bara to about 20 bara.
In some embodiments, the composition comprises from about 74 mol% to about 92 mol% 1234zeE and from about 8 mol% to about 26 mol% 245cb at temperatures of about -20°C to about 70°C and pressures of about 1 bara to about 16 bara. In further embodiments, the composition comprises from about 76 mol% to about 92 mol% 1234zeE and from about 8 mol% to about 24 mol% 245cb at temperatures of about 0°C to about 70°C and pressures of about 2 bara to about 16 bara. In further embodiments, the composition comprises from about 80 mol% to about 92 mol% 1234zeE and from about 8 mol% to about 20 mol% 245cb at temperatures of from about 30°C to about 70°C and pressures of about 6 bara to about 16 bara.
In an alternative embodiment, the azeotropic or near-azeotropic composition of the invention may also comprise a lubricant. Such lubricants may be selected from the group consisting of mineral oil, silicone oil, polyalkyl benzenes (PABs), polyol esters (POEs), polyalkylene glycols (PAGs), polyalkylene glycol esters (PAG esters), polyvinyl ethers (PVEs), poly (alpha-olefins) and combinations thereof, preferably wherein the lubricant is selected from PAGs or POEs.
In a further embodiment, the azeotropic or near-azeotropic composition of the invention may also comprise a stabiliser. Such stabilisers may be selected from the group consisting of diene-based compounds, phosphates, phenol compounds and epoxides, and mixtures thereof.
In an alternative embodiment, the azeotropic or near-azeotropic composition of the invention may also comprise a flame retardant. Such flame retardants my be selected from the group consisting of tri-(2-chloroethyl)-phosphate, (chloropropyl) phosphate, tri-(2,3-dibromopropyl)-phosphate, tri-(1,3-dichloropropyl)-phosphate, diammonium phosphate, various halogenated aromatic compounds, antimony oxide, aluminium trihydrate, polyvinyl chloride, a fluorinated iodocarbon, a fluorinated bromocarbon, trifluoro iodomethane, perfluoroalkyl amines, bromo-fluoroalkyl amines and mixtures thereof.
In another aspect, the invention provides the use of the or a azeotropic or near-azeotropic composition comprising CH3CF2CF3 (245cb) and CHFCHCF3 (1234zeE) (e.g. as an intermediate) in the manufacture of one or more hydrofluoroolefins. For example, the azeotropic or near-azeotropic composition of the invention has been found to be particularly useful in the manufacture of CHFCHCF3 (1234zeE) and CH2CFCF3 (1234yf).
In a further aspect, the azeotropic or near-azeotropic composition of the invention has been found to be useful as a heat transfer composition, for example in refrigeration applications including air conditioning.
In a further aspect, the invention provides a process for the separation of an azeotropic or near-azeotropic composition comprising CH3CF2CF3 (245cb) and CHFCHCF3 (1234zeE) comprising separating the composition via the use of a pressure swing apparatus. Such pressure swing apparatus set-ups may comprise at least two columns, which may be operated sequentially at different pressures. Similarly, the columns may be operated sequentially at two different temperatures.
In an embodiment, a first column A may be operated at a pressure of from about 5 to about 30 bara, such as from about 10 to about 25 bara, preferably from about 15 to about 20 bara. Advantageously, column A is operated at a pressure of about 16 bara.
In a further embodiment, a second column B may be operated at a pressure of from about 1 to about 5 bara, such as 1, 2, 3, 4 or 5 bara. Preferably, column B is operated at a pressure of about 2 bara.
In another embodiment, column A is operated at a temperature of from about 60°C to about 80°C, such as from about 70°C to about 80 °C, preferably from about 70°C to about 75°C. In one embodiment, a temperature gradient exists in column A where the temperature varies from 70°C at one end of the column to 74°C at the other end.
In another embodiment, column B is operated at a temperature of from about -10°C to about +10°C, such as from about -5°C to about +5 °C, preferably from about -5°C to about 0°C. Advantageously, a temperature gradient exists in column B where the temperature varies from -3°C at one end of the column to -2°C at the other end.
In an embodiment, an azeotropic or near-azeotropic feed composition (Fi) of the invention comprising 245cb and 1234zeE is fed into column A. Such compositions may comprise, or preferably consist of, 50 mol% to about 95 mol% 1234zeE and from about 50 mol% to about 5 mol% 245cb, advantageously from about 60 mol% to about 90 mol% 1234zeE and from about 40 mol% to about 10 mol% 245cb, such as about 60 mol% to about 85 mol% 1234zeE and from about 40 mol% to about 15 mol% 245cb, for example about 70 mol% to about 85 mol% 1234zeE and from about 30 mol% to about 15 mol% 245cb, preferably about 70 mol% to about 80 mol% 1234zeE and from about 30 mol% to about 20 mol% 245cb. Advantageously, the Fi composition consists of about 70 mol% 1234zeE and about 30 mol% 245cb.
On entering column A, 245cb is separated from the Fi composition. As such, 245cb may be recovered from column A yielding a 245cb rich composition (Di) comprising greater than about 90 mol% 245cb, such as greater than about 95 mol% 245cb, preferably greater than 99 mol% 245cb, such as 100 mol% 245cb. Preferably, composition Di is recovered from column A at the higher temperature region of the column.
On recovering the composition Di from column A, a preferably azeotropic or near-azeotropic composition (Ci) comprising 245cb and 1234zeE may be recovered at the opposite end of the column. As 245cb has been recovered from composition Fi, the Ci composition is richer in 1234zeE than Fi. Preferably, such compositions comprise, or preferably consist of, about 5 mol% to about 20 mol% 245 cb and from about 95 mol% to about 80 mol% 1234zeE, such as from about 5 mol% to about 10 mol% 245cb and from 95 mol% to about 90 mol% 1234zeE. Preferably, such compositions comprise, or preferably consist of, 9 mol% 245cb and 91 mol% 1234zeE.
The recovery of compositions Di and Ci from column A may occur simultaneously or sequentially. Preferably, the recovery of compositions Di and Ci occurs simultaneously.
After separation, the Ci composition may be fed into column B, wherein 1234zeE is separated from the Ci composition. As such, 123zeE may be recovered from composition Ci yielding a 1234zeE rich composition (D2) comprising greater than about 90 mol% 1234zeE, such as greater than about 95 mol% 1234zeE, preferably greater than 99 mol% 1234zeE, such as 100 mol% 1234zeE. Preferably, composition D2 is recovered from column B at the higher temperature region of the column.
On recovering the composition D2 from column B, a preferably azeotropic or near-azeotropic composition (C2) consisting of 245cb and 1234zeE may be recovered at the opposite end of the column. As 1234zeE has been recovered from composition C-i, the C2 composition is richer in 245cb than Ci. Preferably, such compositions comprise, or preferably consist of, about 10 mol% to about 30 mol% 245 cb and from about 90 mol% to about 70 mol% 1234zeE, such as from about 20 mol% to about 30 mol% 245cb and from 80 mol% to about 70 mol% 1234zeE. Preferably, such compositions comprise, or preferably consist of, 30 mol% 245cb and 70 mol% 1234zeE. Advantageously, the molar ratio of 245cb to 1234zeE in C2 is essentially the same as the molar ratio of 245cb to 1234zeE in F-i.
The recovery of compositions D2 and C2 from column B may occur simultaneously or sequentially. Preferably, the recovery of compositions D2 and C2 occurs simultaneously.
In an embodiment, upon recovery of the composition C2from column B, this composition may be recycled back into column A. Preferably, this process is, therefore, continuous.
Although it is preferred that the separation of composition Fi is via first entering column A then column B, it is envisaged that the process may be reversed and the azeotropic or near-azeotropic composition may be subjected to the separation process in column B first before being subjected to the separation process in column A.
In another aspect, the invention provides a process for the preparation of CH2CFCF3 (1234yf), the process comprising: a) dehydrofluorinating CH3CF2CF3 (245cb) to produce a reaction product comprising 1234yf, CHFCHCF3 (1234ze(E)(Z)) and CF2CH2CF3 (245fa); b) separating 1234yf, 1234ze(Z) and 245fa from the reaction product yielding an azeotropic or near-azeotropic composition of the invention as described above; and c) recycling the azeotropic or near-azeotropic composition of step (b) into step (a).
In an embodiment, the recycling step may include a pressure swing separation process as disclosed above, which allows the recycling of the azeotropic composition back into step (a) and the at least partial recovery of 1234ze(E).
In an embodiment, the dehydrofluorination step (a) comprises a catalyst. Such catalysts may comprise activated carbon, alumina and/or chromia orzinc/chromia. Alternatively, the catalyst may be activated carbon, Pd/carbon, Pt/carbon, Au/carbon, Pd/alumina, Ni/alumina, Pt/alumina, Cr/alumina or Zn/chromia. In another embodiment, the catalyst may be a Lewis acid catalyst, such as SnCU.
The inventors have found that the dehydrofluorination of HFC-245cb can produce significant quantities of 1234-ze(Z)(E) and its precursors in addition to the expected 1234yf. With the present application, the inventors have surprisingly found that an azeotropic or near-azeotropic composition as defined above exists between 245cb and 1234zeE and is formed during the dehydrofluorination of 245cb. This azeotropic or near-azeotropic composition is difficult to separate. However, the inventors have unexpectedly found that this azeotropic or near-azeotropic composition may be recycled back into step (a) above using a pressure swing apparatus as defined above, which results in a more efficient and economical process for the preparation of 1234yf.
Embodiments of the present invention will now be described with reference to the following drawings:
Figure 1 shows a pressure swing apparatus set-up, which is suitable for the separation of azeotropic or near-azeotropic compositions of the invention.
Figures 2 and 3 show the results obtained when measuring the vapour pressure of varying compositions of 245cb and 1234zeE at temperatures of 30°C and 70°C.
Figures 4 to 6 show the results obtained when measuring the vapour mole fraction of 1234zeE and liquid mole fraction of 1234zeE using varying compositions of 245cb and 1234zeE at temperatures of 0°C to 70°C.
The present invention provides an azeotropic or near-azeotropic composition comprising 1234zeE and 245cb. Without wishing to be bound by theory, the existence of an azeotropic or near-azeotropic composition is generally dependent on temperature, pressure and the ratio of components in the composition. For example, in an embodiment, for compositions comprising about 74 mol% 1234zeE and 26 mol% 245cb the azeotropic or near-azeotropic composition of the invention exists at temperatures of about -20°C and pressures of about 1.0 bara. For compositions comprising about 76 mol% 1234zeE and 24 mol% 245cb the azeotropic or near-azeotropic composition of the invention exists at temperatures of about 0°C and pressures of about 2.2 bara. For compositions comprising about 80 mol% 1234zeE and 20 mol% 245cb the azeotropic or near-azeotropic composition of the invention exists at temperatures of about 30°C and pressures of about 5.9 bara. Whereas, for compositions comprising about 92 mol% 1234zeE and about 8 mol% 245cb the azeotropic or near-azeotropic composition of the invention exists at temperatures of about +70°C and pressures of about 16.1 bara. By varying the temperature, pressure and composition, an azeotrope or near-azeotrope composition of the invention may occur at any point between these values.
The components of azeotropic or near-azeotropic compositions may be separated via the use of a pressure swing distillation apparatus. Such set-ups typically comprise one or more distillation columns operated at temperatures and pressures specific to the azeotropic or near-azeotropic composition of interest. By fine tuning the temperature and pressure of the pressure swing distillation column(s), an azeotrope composition may be distilled from the column, wherein, depending on the pressure and temperature of the column, the resulting distillate may comprise the components of the azeotropic composition in different molar ratios than that of the original feed composition. This, therefore, can result in the liquid phase that is left in the column being richer in one component of the azeotropic composition than the other. In some cases, the liquid phase may be almost 100 mol% of the component left in the liquid phase.
An exemplary pressure swing apparatus set-up for the separation of azeotropic or near-azeotropic compositions of the invention is provided in Figure 1. This set-up comprises two columns (A and B), which are operated at different temperatures and pressures. Preferably, column A is operated at a higher pressure to the second column B. However, it is envisaged that column B may be operated at a higher pressure to column A. Similarly, column A is preferably operated at higher temperatures to column B. However, column B may just as easily be operated at higher temperatures to column A if the process requires.
In a specific embodiment, and with reference to Figure 1, a feed composition (Fi) comprising about 30 mol% 245cb and about 70 mol% 1234zeE is fed into column A, which is operated at a pressure of about 16 bara and temperatures of about 74°C at the bottom of the column and 70°C at the top. Under these conditions, the Fi composition undergoes partial distillation, wherein a distillate composition (Ci) is distilled from the top of the column leaving a 245cb rich residue (Di). After this first separation process, the Ci composition comprises about 9 mol% 245cb and about 91 mol% 1234zeE. Whereas, the Di residue composition comprises about 99 to about 100 mol% 245cb. The highly pure Di composition is removed from the column and collected, and the Ci composition is fed into column B, which is operated at a pressure of 2 bara and temperatures of -2°C at the bottom of the column and -3°C at the top. Under such conditions, the Ci composition undergoes distillation to provide a distillate composition (C2) comprising about 30 mol% 245cb and about 70 mol% 1234zeE, which results in a 1234zeE rich residue (D2) remaining in the column. This D2 residue typically comprises about 99 mol% to about 100 mol% 1234zeE. After the separation process in column B, the highly pure D2 composition is removed from the column and collected, and the distillate composition C2 is recylced back into column A to repeat the process.
Examples
Example 1 A binary azeotrope between 245cb and 1234zeE was identified by a study of the vapour-liquid equilibrium of binary mixtures over a temperature range of -20°C to +70°C using a constant volume apparatus.
The experimental data were measured in a static constant volume apparatus consisting of a vessel of precisely known internal volume located in a temperature-controlled metal block. A magnetic stirring device was located inside the vessel. Refrigerated fluid was passed through the block to allow precise control of temperature inside the vessel. The cell was evacuated then known amounts of compositions of 245cb and 1234zeE were charged to the cell. The temperature of the cell was then varied to temparatures between -20°C and +70°C. At each step the cell temperatures and pressure were logged and recorded when stable conditions were reached.
The phase behaviour of these compositions at exemplary temperatures is illustrated in Figures 2 to 6. The graphs in Figures 2 and 3 show that a constant vapour pressure is reached at compositions wherein 1234zeE is present in an amount of from about 65 mol% to about 95 mol% and 245cb is present in an amount of from about 35 mol% to about 5 mol%, which is consistent with what would be expected of azeotropic compositions. This trend is evidenced across all temperature ranges tested.
The graphs in Figures 4 to 6 show that the composition of the vapour phase and liquid phase of a 245cb and 1234zeE binary mixture is the same, or essentially the same, in compositions wherein 1234zeE is present in an amount of from about 65 mol% to about 95 mol% and 245cb is present in an amount of from about 35 mol% to about 5 mol%, which is consistent with what would be expected of azeotropic compositions.
Preferences and options for a given aspect, feature or parameter of the invention should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all preferences and options for all other aspects, features and parameters of the invention.

Claims (53)

Claims
1. An azeotropic or near-azeotropic composition comprising CH3CF2CF3 (245cb) and CHFCFICF3 (1234zeE).
2. A composition according to Claim 1 consisting essentially of 245cb and 1234zeE.
3. A composition according to Claim 1 or Claim 2 consisting of 245cb and 1234zeE.
4. A composition according to any one of Claims 1 to 3 containing from about 50 mol% to about 95 mol% 1234zeE and from about 50 mol% to about 5 mol% 245cb.
5. A composition according to Claim 4 comprising from about 60 mol% to about 98 mol% 1234zeE and from about 40 mol% to about 2 mol% 245cb, such as about 60 mol% to about 85 mol% 1234zeE and from about 40 mol% to about 15 mol% 245cb, for example about 70 mol% to about 85 mol% 1234zeE and from about 30 mol% to about 15 mol% 245cb, preferably about 70 mol% to about 80 mol% 1234zeE and from about 30 mol% to about 20 mol% 245cb.
6. A composition according to any one of the preceding claims, wherein the azeotropic or near-azeotropic composition is present at temperatures of from about-30°C to about +80°C
7. A composition according to Claim 6, wherein the azeotropic or near-azeotropic composition is present at temperatures of from about 0°C to about +70°C, preferably from temperatures of from about +30°C to about +70°C
8. A composition according to any one of the preceding claims, wherein the azeotropic or near-azeotropic composition is present at pressures of from about 0.5 bara to about 30 bara, for example from about 10 to about 25 bara, preferably about 15 to about 20 bara.
9. A composition comprising a lubricant and a composition according to any of the preceding claims.
10. A composition according to claim 9, wherein the lubricant is selected from mineral oil, silicone oil, polyalkyl benzenes (PABs), polyol esters (POEs), polyalkylene glycols (PAGs), polyalkylene glycol esters (PAG esters), polyvinyl ethers (PVEs), poly (alpha-olefins) and combinations thereof, preferably wherein the lubricant is selected from PAGs or POEs.
11. A composition comprising a stabiliser and a composition according to any of the preceding claims.
12. A composition according to Claim 11, wherein the stabiliser is selected from diene-based compounds, phosphates, phenol compounds and epoxides, and mixtures thereof.
13. A composition comprising a flame retardant and a composition according to any of the preceding claims.
14. A composition according to Claim 13, wherein the flame retardant is selected from the group consisting of tri-(2-chloroethyl)-phosphate, (chloropropyl) phosphate, tri-(2,3-dibromopropyl)-phosphate, tri-(1,3-dichloropropyl)-phosphate, diammonium phosphate, various halogenated aromatic compounds, antimony oxide, aluminium trihydrate, polyvinyl chloride, a fluorinated iodocarbon, a fluorinated bromocarbon, trifluoro iodomethane, perfluoroalkyl amines, bromo-fluoroalkyl amines and mixtures thereof.
15. The use of a composition (e.g. as an intermediate) according to any one of the preceding claims in the manufacture of one or more hydrofluoroolefins.
16. The use according to Claim 15, wherein the manufactured hydrofluoroolefin is one or both of CHFCHCFs (1234zeE) or CH2CFCF3 (1234yf).
17. The use of a composition according to any one of claims 1 to 14 as a heat transfer composition.
18. A heat transfer composition comprising a composition according to any one of Claims 1 to 14.
19. A method for cooling an article which comprises condensing a composition as defined in any one of Claims 1 to 14 and thereafter evaporating the composition in the vicinity of the article to be cooled.
20. A method for heating an article which comprises condensing a composition as defined in any one of Claims 1 to 14 in the vicinity of the article to be heated and thereafter evaporating the composition.
21. A mechanical power generation device containing a composition as defined in any one of Claims 1 to 14.
22. A mechanical power generating device according to Claim 21 which is adapted to use a Rankine Cycle or modification thereof to generate work from heat.
23. A method of retrofitting a heat transfer device comprising the step of removing an existing heat transfer composition, and introducing a composition as defined in any one of Claims 1 to 14.
24. A method according to Claim 23 wherein the heat transfer device is a refrigeration device.
25. A method according to Claim 23 wherein the heat transfer device is an air conditioning system, preferably an automobile air conditioning system.
26. A method for reducing the environmental impact arising from the operation of a product comprising an existing compound or composition, the method comprising replacing at least partially the existing compound or composition with a composition as defined in any one of claims 1 to 14.
27. A method for generating greenhouse gas emission credit comprising (i) replacing an existing compound or composition with a composition as defined in any one of claims 1 to 14, wherein the composition as defined in any one of claims 1 to 14 has a lower GWP than the existing compound or composition; and (ii) obtaining greenhouse gas emission credit for said replacing step.
28. A method according to Claim 27 wherein the use of the composition of the invention results in a lower Total Equivalent Warming Impact, and/or a lower Life-Cycle Carbon Production than is attained by use of the existing compound or composition.
29. A method according to Claims 27 or 28 carried out on a product from the fields of air-conditioning, refrigeration, heat transfer, blowing agents, aerosols or sprayable propellants, gaseous dielectrics, cryosurgery, veterinary procedures, dental procedures, fire extinguishing, flame suppression, solvents, cleaners, air horns, pellet guns, topical anesthetics, and expansion applications.
30. A process for the separation of an azeotropic or near-azeotropic composition according to any one of Claims 1 to 8.
31. A process according to Claim 30, wherein the azeotropic or near-azeotropic composition is separated via the use of a pressure swing distillation.
32. A process according to Claims 30 or 31, wherein the pressure swing apparatus comprises two columns operated sequentially at different pressures.
33. A process according to any one of Claim 32, wherein the first column (A) is operated at a higher pressure to the second column (B).
34. A process according to Claim 31 to 33, wherein column A is operated at a pressure of from about 5 to about 30 bara, such as from about 10 to about 25 bara, preferably from about 15 to about 20 bara.
35. A process according to any one of Claims 31 to 34, wherein column B is operated at a pressure of from about 0.5 to about 5 bara, such as 1, 2, 3, 4 or 5 bara.
36. A process according to any one of Claims 31 to 35, wherein the two columns are operated sequentially at different temperatures.
37. A process according to Claim 36, wherein column A is operated at a temperature of from about 60°C to about 80°C, such as from about 70°C to about 80 °C, preferably from about 70°C to about 75°C.
38. A process according to Claims 36 or 37, wherein column B is operated at a temperature of from about-10°C to about +10°C, such as from about-5°C to about +5 °C, preferably from about -5°C to about 0°C.
39. A process according to any one of Claims 31 to 38, wherein the azeotropic or near-azeotropic feed composition (Fi) comprises 50 mol% to about 95 mol% 1234zeE and from about 50 mol% to about 5 mol% 245cb, advantageously from about 60 mol% to about 90 mol% 1234zeE and from about 40 mol% to about 10 mol% 245cb, such as about 60 mol% to about 85 mol% 1234zeE and from about 40 mol% to about 15 mol% 245cb, for example about 70 mol% to about 85 mol% 1234zeE and from about 30 mol% to about 15 mol% 245cb, preferably about 70 mol% to about 80 mol% 1234zeE and from about 30 mol% to about 20 mol% 245cb.
40. A process according to any one of Claims 31 to 39, wherein the Fi composition is separated into two liquid compositions in column A, wherein 245cb is separated from the azeotrope composition to yield a composition (Di) comprising greater than about 90 mol% 245cb, such as greater than about 95 mol% 245cb, preferably greater than 99 mol% 245cb, and an azeotropic or near-azeotropic composition (Ci) comprising 245cb and 1234zeE in a molar ratio that is richer in 1234zeE than Fi.
41. A process according to any one of Claims 31 to 40, wherein Di is removed from the separating apparatus and Ci is fed into column B, wherein the Ci composition is separated into two further liquid compositions, wherein 1234zeE is separated from the azeotrope composition to yield a composition (D2) comprising greater than about 90 mol% 1234zeE, such as greater than about 95 mol% 1234zeE, preferably greater than 99 mol% 1234zeE, and an azeotropic or near-azeotropic composition (C2) comprising 245cb and 1234zeE in a molar ratio that is richer in 245cb than Ci.
42. A process according to any one of Claims 31 to 41, wherein composition D2 is removed from the separating apparatus and composition C2 is recycled back into column A.
43. A process according to Claims 31 to 42, wherein the molar ratio of 245cb to 1234zeE in C2 is essentially the same as the molar ratio of 245cb to 1234zeE in Fi.
44. A process according to any one of Claims 31 to 43, wherein the process is continuous.
45. A process according to any one of Claims 37 to 44, wherein the azeotropic or near-azeotropic composition is subjected to the separation process in column B first before being subjected to the separation process in column A.
46. A process for preparing CFI2CFCF3 (1234yf), the process comprising: a) dehydrofluorinating CFl3CF2CF3 (245cb) to produce a reaction product comprising 1234yf, CHFCHCFs (1234ze(E)(Z)) and CF2CH2CF3 (245fa); b) separating 1234yf, 1234ze(Z) and 245fa from the reaction product yielding an azeotropic or near-azeotropic composition according to any one of Claims 1 to 8; and c) recycling the azeotropic or near-azeotropic composition of step (b) into step (a).
47. A process according to Claim 46, wherein the recycling step includes a pressure swing separation process according to any one of Claims 31 to 45 in order to recycle the azeotropic composition back into step (a) and partially recover 1234ze(E).
48. A process according to Claim 46, wherein the dehydrofluorination step (a) comprises a catalyst.
49. A process according to Claim 48, wherein the catalyst comprises activated carbon, alumina and/or chromia or zinc/chromia.
50. A process according to Claim 48, wherein the catalyst is activated carbon, Pd/carbon, Pt/carbon, Au/carbon, Pd/alumina, Ni/alumina, Pt/alumina, Cr/alumina or Zn/chromia.
51. A process according to Claim 48, wherein the catalyst is a Lewis acid catalyst.
52. A process according to Claim 51, wherein the Lewis acid catalyst is SnCL.
53. Any novel composition, method or process as described herein, optionally with reference to the examples.
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US11565992B2 (en) 2020-11-13 2023-01-31 Honeywell International Inc. Methods for separation of azeotrope or azeotrope-like compositions of trifluoroiodomethane (CF3I) and trifluoroacetyl chloride (CF3COCI)

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