Patent Application
20100113323
1. Field of Invention
The present invention is directed to azeotrope-like compositions. More particularly, the invention is directed to azeotrope-like compositions comprising a hydrofluoroolefin and hydrogen fluoride.
2. Description of the Prior Art
Many azeotropes possess properties that make them useful as solvents. For example, azeotropes have a constant boiling point that avoids boiling temperature drift during processing and use. In addition, when an azeotrope is used as a solvent, the properties of the solvent remain constant because the composition of the solvent does not change during boiling or reflux. Azeotropes that are used as solvents also can be recovered conveniently by distillation.
However, the identification of new, environmentally-safe, non-fractionating mixtures that are commercially useful complicated due to the fact that azeotrope formation is not readily predictable. Therefore, industry is continually seeking new azeotrope and azeotrope-like mixtures. This invention satisfies these needs among others.
A heteroazeotrope-like composition has been found that consists essentially of 1,1,1,2,3-pentachloropropane (HFC-240db) and hydrogen fluoride (HF). This azeotrope-like composition is useful as a solvent in various application, such as removing surface oxidation from metals. Moreover, this azeotrope-like composition is useful as an intermediate in the synthesis of certain hydrofluoroolefins, such as HFO-1234yf.
Accordingly, provided is an azeotrope-like composition consisting essentially of 1,1,1,2,3-pentachloropropane and hydrogen fluoride.
In another aspect of the invention, provided is a method for forming an azeotropic or azeotrope-like composition comprising blending hydrogen fluoride with 1,1,1,2,3-pentachloropropane at a temperature of from about 0° C. to about 60° C. and at a pressure of about 7 psia to about 58 psia to produce an azeotrope-like mixture consisting essentially of about 1 to about 95 weight percent hydrogen fluoride and from about 5 to about 99 weight percent 1,1,1,2,3-pentachloropropane.
In yet another aspect of the invention, provided is a solvent comprising an azeotrope-like composition consisting essentially of 1,1,1,2,3-pentachloropropane and hydrogen fluoride.
In another aspect of the invention, provided is a sprayable composition comprising an azeotrope-like composition consisting essentially of 1,1,1,2,3-pentachloropropane and hydrogen fluoride.
And in other aspect of the invention, provided is a method for removing surface oxidation from a substrate comprising contacting an oxidized surface of a metal substrate with a solvent comprising the novel azeotrope-like compositions described herein under conditions effective to remove an amount of metal oxides from said surface
The present invention provides compositions which comprise hydrogen fluoride (HF) and 1,1,1,2,3-pentachloropropane (HFC-240db) in amounts effective to form an azeotrope-like composition, as well as methods involving such azeotrope-like compositions. In certain preferred embodiments, these azeotrope-like compositions are binary azeotropes which consist essentially of combinations of only hydrogen fluoride with HFC-240db.
As used herein, the term “azeotrope-like” relates to compositions that are strictly azeotropic and/or that generally behave like azeotropic mixtures. An azeotropic mixture is a system of two or more components in which the liquid composition and vapor composition are equal at the stated pressure and temperature. In practice, this means that the components of an azeotropic mixture are constant-boiling or essentially constant-boiling and generally cannot be thermodynamically separated during a phase change. The vapor composition formed by boiling or evaporation of an azeotropic mixture is identical, or substantially identical, to the original liquid composition. Thus, the concentration of components in the liquid and vapor phases of azeotrope-like compositions change only minimally, if at all, as the composition boils or otherwise evaporates. In contrast, boiling or evaporating non-azeotropic mixtures changes the component concentrations in the liquid phase to a significant degree.
As used herein, the terms “heteroazeotrope” and “heterogeneous azeotrope” mean an azeotrope-like composition comprising a vapor phase concurrently with two liquid phases.
As used herein, the term “consisting essentially of”, with respect to the components of an azeotrope-like composition, means the composition contains the indicated components in an azeotrope-like ratio, and may contain additional components provided that the additional components do not form new azeotrope-like systems. For example, azeotrope-like mixtures consisting essentially of two compounds are those that form binary azeotropes, which optionally may include one or more additional components, provided that the additional components do not render the mixture non-azeotropic and do not form an azeotrope with either or both of the compounds (e.g., do not form a ternary azeotrope).
The term “effective amounts” as used herein refers to the amount of each component which, upon combination with the other component, results in the formation of an azeotrope-like composition of the present invention.
The term “dispensed form” as used herein refers to a physical form of a fluid as it is spread, distributed, and/or diffused over an area or through a volume. Examples of dispensed forms include aerosols and sprays.
In certain preferred embodiments, the azeotrope-like composition contains from about 1 to about 90 weight percent HF and from about 10 to about 99 weight percent HFC-240db, more preferably from about 5 weight percent to about 88 weight percent HF and from about 12 weight percent to about 95 weight percent HFC-240db, most preferably from about 55 weight percent to about 85 weight percent HF and from about 15 weight percent to about 45 weight percent HFC-240db.
The composition of the present invention preferably has a boiling point of from about 0° C. to about 60° C. at a pressure from about 7 psia to about 52 psia. For example, a preferred azeotrope-like composition consists essentially of about 85±2 weight percent HF and about 15±2 weight percent HFC-240db and has a normal boiling point of about 23° C.
The azeotrope-like compositions of the present invention can be produced by combining effective amounts of HFC-240db with HF. Any of a wide variety of methods known in the art for combining two or more components to form a composition can be adapted for use in the present methods. For example, HFC-240db and HF can be mixed, blended, or otherwise combined by hand and/or by machine, as part of a batch or continuous reaction and/or process, or via combinations of two or more such steps. In light of the disclosure herein, those of skill in the art will be readily able to prepare azeotrope-like compositions according to the present invention without undue experimentation.
In another embodiment of the invention, the azeotrope-like compositions described herein can be used as a solvent, particularly a cleaning solvent. In certain embodiments, the solvent is contacted with an oxidized surface of a metal substrate to remove or reduce at least a potion of the oxidized surface. Such solvents may be applied to the targeted substrate via any means known in the art, such as dipping, spraying, wiping, and the like.
In certain preferred embodiments, provided is a sprayable composition comprising the novel azeotrope-like compositions described herein. In certain embodiments, the sprayable composition is an aerosol. In certain the sprayable composition further comprises other components such as inert ingredients, co-solvents, propellants, co-propellants, and the like. In certain embodiments, the novel azeotrope-like compositions described herein are useful intermediates derived from during synthesis of certain hydrofluoroolefins, such as 2,3,3,3-tetrafluoropropene (HFO-1234yf). For example, where HFC-240db and HF are introduced into a reactor during a HFO-1234yf synthesis reaction, at least a portion of these components form an azeotrope which subsequently can be recovered from the associated reaction product stream.
The invention is further illustrated in the following example which is intended to be illustrative, but not limiting in any manner.
Approximately 15 g of 1,1,1,2,3-pentachloropropane (HFC-240db) was blended in 85 g of HF to at about 23° C. and about 14.4 psia. The formation of a heterogeneous azeotrope-like composition was observed.
HFC-240db and HF were blended to form a heterogeneous azeotrope mixtures at different compositions. The vapor pressures of the mixtures are measured at about 0, 25, and 60° C. The results of these measurements are provided in Table 1.
The data in Table 1 demonstrates that these mixtures exhibit azeotrope-like characteristics since the vapor pressures of mixtures of HFC-240db and HF are higher, at all indicated blend proportions, than HFC-240db and HF alone, i.e. as indicated in the first and last rows when HF is 0.0 wt. % and HFC-240db is at 100.0 wt % as well as when HFC-240db is at 0.0 wt. % and HF is at 100.0 wt. %.
The data from Table 1 is depicted graphically in
This example demonstrates the azeotropic-like properties of HFC-240db/HF mixtures via Vapor-Liquid-Liquid Equilibrium (VLLE).
Approximately 14.6 g of 1,1,1,2,3-pentachloropropane (HFC-240db) was blended with 16.8 g of HF to form, upon visual observation, a heterogeneous mixture at 23° C. The vapor compositions of the two mixtures were sampled at room temperature of 23° C. The result shows an azeotrope-like composition was formed having about 85±2 wt. % HF at 23° C.
This application claims the priority benefit of U.S. Provisional Application No. 61/110,216, filed Oct. 31, 2008, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61110216 | Oct 2008 | US |
