Compositions of pentafluoropropane and dichlorotrifluoroethane

Details Compositions of pentafluoropropane and dichlorotrifluoroethane Compositions of pentafluoropropane and dichlorotrifluoroethane

1999-12-20

2002-03-26

Cooney, Jr., John M. (Department: 1711)

Cleaning compositions for solid surfaces, auxiliary compositions

Cleaning compositions or processes of preparing

Liquid composition

C510S415000

Reexamination Certificate

active

06362153

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to mixtures of 1,1,1,3,3-pentafluoropropane (“HFC-245fa”) and 1,1-dichloro-2,2,2-trifluoroethane (“HCFC-123”). More particularly, the invention provides compositions of HFC-245fa and HCFC-123 that are environmentally desirable for use as refrigerants, in centrifugal chillers, aerosol propellants, metered dose inhalers, fire extinguishers, blowing agents for polymer foam, heat transfer media, gaseous dielectrics, and solvents.
BACKGROUND OF THE INVENTION
Fluorocarbon based fluids have found widespread use in industry in a number of applications, including as refrigerants, aerosol propellants, blowing agents, heat transfer media, and gaseous dielectrics. Because of the suspected environmental problems associated with the use of some of these fluids, it is desirable to use fluids of lesser ozone depletion potential such as hydrofluorocarbons, (“HFC's”) and/or hydrochlorofluorocarbons (“HCFC's”).
Thus, the use of fluids that do not contain CFC's or contain HCFC's instead of CFC's is desirable. Additionally, it is known that the use of single component fluids or azeotropic mixtures, which mixtures do not fractionate on boiling and evaporation, is desirable. However, the identification of new, environmentally safe, azeotropic mixtures is complicated due to the fact that it is difficult to predict azeotrope formation.
The art continually is seeking new fluorocarbon based mixtures that offer alternatives, and are considered environmentally safe substitutes, for CFC's and HCFC's. Of particular interest are mixtures containing a fluorocarbon and hydrochlorocarbon both of low ozone depletion potentials; it is these mixtures that are the subject of this invention.
DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
This invention provides azeotrope-like and nonazeotrope-like compositions of HFC-245fa and HCFC-123. The compositions of the invention provide environmentally desirable for currently used CFC's and HCFC's since HFC-245fa and HCFC-123 have zero and very low ozone depletion potentials, respectively. Additionally, the compositions of the invention exhibit characteristics that make the compositions better CFC and HCFC substitutes than either HFC-245fa or HCFC-123 alone.
One embodiment of the invention provides azeotrope-like compositions comprising effective amounts of HFC-245fa and HCFC-123. By “effective amounts” is meant the amount of each component that, on combination with the other component, results in the formation of an azeotrope-like composition. More specifically, the invention provides azeotrope-like compositions preferably of from about 90 to about 99 weight percent HFC-245fa and from about 10 to about 1 weight percent HCFC-123 having a boiling point of 15° C.±2, preferably±1° C., at 760 mm. The preferred, more preferred, and most preferred compositions of the invention are set forth in Table 1. The numerical ranges in Table 1 are to be understood to be prefaced by the term “about”.
TABLE 1
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Most
Components
Preferred (wt %)
Preferred (wt %)
Preferred (wt %)
HFC-245fa
90-99
94-99
97-99
HCFC-123
10-1 
 6-1 
 3-1 
For purposes of this invention, azeotrope-like compositions are compositions that behave like azeotropic mixtures. From fundamental principles, the thermodynamic state of a fluid is defined by pressure, temperature, liquid composition, and vapor composition. An azeotropic mixture is a system of two or more components in which the liquid composition and vapor composition are equal at the state pressure and temperature. In practice, this means that the components of an azeotropic mixture are constant boiling and cannot be separated during a phase change.
Azeotrope-like compositions behave like azeotropic mixtures, i.e., are constant boiling or essentially constant boiling. In other words, for azeotrope-like compositions, the composition of the vapor formed during boiling or evaporation is identical, or substantially identical, to the original liquid composition. Thus, with boiling or evaporation, the liquid composition changes, if at all, only to a minimal or negligible extent. This is to be contrasted with non-azeotrope-like compositions in which, during boiling or evaporation, the liquid composition changes to a substantial degree. All azeotrope-like compositions of the invention within the indicated ranges as well as certain compositions outside these ranges are azeotrope-like.
The azeotrope-like compositions of the invention may include additional components that do not form new azeotropic or azeotrope-like systems, or additional components that are not in the first distillation cut. The first distillation cut is the first cut taken after the distillation column displays steady state operation under total reflux conditions. One way to determine whether the addition of a component forms a new azeotropic or azeotrope-like system so as to be outside of this invention is to distill a sample of the composition with the component under conditions that would be expected to separate a nonazeotropic mixture into its separate components. If the mixture containing the additional component is nonazeotropic or nonazeotrope-like, the additional component will fractionate from the azeotropic or azeotrope-like components. If the mixture is azeotrope-like, some finite amount of a first distillation cut will be obtained that contains all of the mixture components that is constant boiling or behaves as a single substance.
It follows from this that another characteristic of azeotrope-like compositions is that there is a range of compositions containing the same components in varying proportions that are azeotrope-like, or constant boiling. All such compositions are intended to be covered by the terms “azeotrope-like” and “constant boiling”. As an example, it is well known that at differing pressures, the composition of a given azeotrope will vary at least slightly as does the boiling point of the composition. Thus, an azeotrope of A and B represents a unique type of relationship, but with a variable composition depending on temperature and/or pressure. It follows that, for azeotrope-like compositions, there is a range of compositions containing the same components in varying proportions that are azeotrope-like. All such compositions are intended to be covered by the term azeotrope-like as used herein.
In another embodiment of the invention, nonazeotrope-like compositions are provided which compositions comprise HFC-245fa and HCFC-123 and which have a vapor pressure of about 18 psia to about 19 psia at 20° C. Preferably, the compositions of the invention comprise from about 90 to about 99 weight percent HFC-245fa and from about 10 to about 1 weight percent HCFC-123a. The preferred, more preferred, and most preferred compositions of this embodiment are set forth in Table 2. The numerical ranges in Table 2 are to be understood to be prefaced by the term “about.”
TABLE 2
More
Most
Components
Preferred (wt %)
Preferred (wt %)
Preferred (wt %)
HFC-245fa
90-99
94-99
97-99
HCFC-123
10-1 
 6-1 
 3-1 
The compositions of the invention meet the need in the art for CFC/HCFC mixtures that have a low ozone depletion potential and are negligible contributors to greenhouse global warming, are nonflammable, and have an appropriate compressor discharge temperature. Additionally, the compositions of the invention offer superior refrigeration capacity when compared to such fluids as HFC-245fa or HCFC-123 alone. Further, because the azeotrope-like compositions of the invention exhibit constant vapor pressure characteristics and relatively minor composition shifts as the liquid mixture is evaporated, the azeotrope-like composition of the invention are comparable to a constant boiling single component refrigerant or an azeotropic mixture refrigerant.
In a process embodiment, the compositions of the invention may be used in a method for producing refrigeration that comprises condensing a refrigerant comprising the azeotrope-like or nona

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