US 2010.0193347A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2010/0193347 A1 Hulse et al. (43) Pub. Date: Aug. 5, 2010

(54) PROCESS FOR THE PURIFICATION OF Related U.S. Application Data HYDROFLUOROOLEFNS (60) Provisional application No. 61/148,505, filed on Jan. 30, 2009. (75) Inventors: Ryan Hulse, Getzville, NY (US); Publication Classification Rajiv Ratna Singh, Getzville, NY (US); Ian Shankland, Randolph, (51) Int. Cl. NY (US); Michael Van Der Puy, BOID 3/36 (2006.01) Amherst, NY (US) (52) U.S. Cl...... 2O3A28 (57) ABSTRACT Correspondence Address: Processes for the preparation and purification of hydrofluo HONEYWELLAFOX ROTHSCHILD roolefins such as tetrafluorinated propenes. A process is pro Patent Services vided for separating a first hydrofluoroolefin from a second 101 Columbia Road hydrofluoroolefin by a) providing a mixture comprising a first Morristown, NJ 07962 (US) hydrofluoroolefin and a second hydrofluoroolefin, which first hydrofluoroolefin is preferentially more reactive with an amine than the second hydrofluoroolefin; b) adding a suffi (73) Assignee: HONEYWELL cient amount of an amine to the mixture to form a combina INTERNATIONAL INC., tion comprising the second hydrofluoroolefin and a reaction Morristown, NJ (US) product of the first hydrofluoroolefin and the amine; and then c) separating the reaction product from the combination. This is particularly useful for removing 1,2,3,3,3-pentafluoropro (21) Appl. No.: 12/696,613 pene (HFO-1225ye) impurities from the hydrofluoroolefin 2,3,3,3-tetrafluoropropene (HFO-1234yf). HFO-1234yf is a (22) Filed: Jan. 29, 2010 with low global warming potential.

Condenser

Purified Amine Purified HFO

Ammonium Salt and/or a higher boiling reaction product Amine with ammonium salt and/or a higher boiling HFO with Amine reaction product H reactive impurity YH -CH

Patent Application Publication Aug. 5, 2010 US 2010/0193347 A1

Condenser

Purified Amine Purified HFO

Ammonium Salt and/or a higher

boiling reaction product Amine with ammonium H reactionSalt and/or product a higher boiling H reactiveHFO with impurity Amine 1H

FIG. 1 US 2010/0193347 A1 Aug. 5, 2010

PROCESS FOR THE PURIFICATION OF 0007 Although most HFC's will not deplete the ozone HYDROFLUOROOLEFNS layer, there is concern about the global warming potential (GWP) associated with these molecules. GWP is a measure of CROSS-REFERENCE TO RELATED the potential contribution to the green house effect of the APPLICATIONS chemical against a reference, the reference molecule in this case is CO which has a GWP-1. Regulation in the European 0001. This application claims the priority benefit of U.S. Union has already set limits of a GWP=150 for to Provisional Application No. 61/148,505, filed Jan. 30, 2009, be used in Some applications such as automotive air condi which is incorporated herein by reference. tioning. 0008 Hydrofluorocarbons (HFCs), particularly hydrof BACKGROUND OF THE INVENTION luoroalkenes Such tetrafluoropropenes, have been disclosed to be effective refrigerants, fire extinguishants, heat transfer 0002 1. Field of the Invention media, propellants, foaming agents, blowing agents, gaseous 0003. The present invention relates to processes for pre dielectrics, sterilant carriers, polymerization media, particu paring hydrofluoroolefins such as tetrafluorinated propenes. late removal fluids, carrier fluids, buffing abrasive agents, 0004 2. Description of the Related Art displacement drying agents and power cycle working fluids. 0005 Fluorocarbon based fluids have found widespread Unlike (CFCs) and hydrochlorofluoro use in many commercial and industrial applications including carbons (HCFCs), both of which potentially damage the as refrigerants, aerosol propellants, blowing agents, heat Earth's ozone layer. HFCs do not contain chlorine and thus transfer media, gaseous dielectrics and as working fluids in pose no threat to the oZone layer. Tetrafluoropropenes, having air conditioning, and refrigeration systems. The Zero oZone depletion and low global warming potential, have vapor compression cycle is one of the most commonly used been identified as potentially filling this need. However, the type methods to accomplish cooling or heating in a refrigera toxicity, boiling point, and other physical properties in this tion system. The vapor compression cycle usually involves class of chemicals vary greatly from isomer to isomer. One the phase change of the refrigerant from the liquid to the vapor tetrafluoropropene having valuable properties is 2,3,3,3-tet phase through heat absorption at a relatively low pressure and rafluoropropene (HFO-1234yf). Thus, there is a need for new then from the vapor to the liquid phase through heat removal manufacturing processes for the production of tetrafluoropro at a relatively low pressure and temperature, compressing the penes and in particular 2,3,3,3-tetrafluoropropene. 2,3,3,3- vapor to a relatively elevated pressure, condensing the vapor Tetrafluoropropene (HFO-1234yf) is a refrigerant that has to the liquid phase through heat removal at this relatively been designed to meet the EU regulations for automotive air elevated pressure and temperature, and then reducing the conditioning. pressure to start the cycle over again. Certain fluorocarbons 0009 U.S. patent application publication US2007/ have been a preferred component in many heat exchange 0179324 discloses a synthesis process involving the dehy fluids. For, example, fluoroalkanes. Such as chlorofluo drofluorination of 1,1,1,2,3-pentafluoropropane (HFC romethane and chlorofluoroethane derivatives, have gained 245eb) to form HFO-1234yf. Also disclosed is the widespread use as refrigerants in applications including air dehydrofluorination of 1,1,1,2,3,3-hexafluoropropane (HFC conditioning and heat pump applications owing to their 236ea) under similar conditions to form 1.2.3,3,3-pentafluo unique combination of chemical and physical properties. ropropene (HFO-1225ye(Z)). Accordingly, the presence of Many of the refrigerants commonly utilized in vapor com HFC-236ea impurities in this reaction could produce HFO pression systems are either single components fluids oraZeo 1225ye(Z) as an unwanted byproduct. To overcome this issue, tropic mixtures. US2007/0179324 also discloses that HFO-1225ye(Z) can be 0006. However, suspected environmental problems asso reacted with to form HFC-245eb, which can be ciated with the use of some of these fluids, including the dehydrofluorinated to form HFO-1234yf. However, any relatively high global warming potentials associated there HFO-1225ye(Z) which is not fully hydrogenated in the first with, it is desirable to use fluids having the lowest possible step will end up as an impurity if the final product stream of greenhouse warming potential in addition to Zero oZone HFO-1234yf. depletion potential. Thus there is considerable interest in 0010 Distillation is a conventional purification method developing environmentally friendlier materials for the appli for commercial processes. Distillation takes advantage of the cations mentioned above. Concern has increased in recent fact that the liquid and vapor of a chemical mixture are at years about potential damage to the earth's atmosphere and different compositions. However, distillation becomes inef climate, and certain chlorine-based compounds have been ficient and then impossible as the chemical mixture identified as particularly problematic in this regard. The use approaches a pinch point and an azeotropic composition, of chlorine-containing compositions (such as chlorofluoro respectively. The closer the composition is to a pinch point the carbons (CFCs), hydrochlorofluorocarbons (HCF's) and the more yield loss there will be in the distillation. This phenom like) as refrigerants in air-conditioning and refrigeration sys ena renders the separation of HFO-1225ye(Z) from a HFO tems has become disfavored because of the ozone-depleting 1234yf product stream using standard distillation techniques properties associated with many of Such compounds. Thus, very difficult. More particularly, it is very difficult to remove there is an increased need for new fluorocarbon and hydrof HFO-1225ye(Z) from HFO-1234yfby conventional distilla luorocarbon compounds and compositions that offer alterna tion at very low levels of HFO-1225ye(Z) without large yield tives for refrigeration and heat pump applications. For losses due to the fact that HFO-1225ye(Z) and HFO-1234yf example, it has become desirable to retrofit chlorine-contain ing refrigeration systems by replacing chlorine-containing form an azeotrope (see U.S. Pat. No. 7,098,176). refrigerants with non-chlorine-containing refrigerant com SUMMARY OF THE INVENTION pounds that will not deplete the ozone layer, such as hydrof 0011. This invention provides a method for preparing high luorocarbons (HFCs). purity hydrofluoroolefin by reacting certain undesirable US 2010/0193347 A1 Aug. 5, 2010 hydrofluoroolefin impurities and/or byproducts with an pentafluoropropene and the second hydrofluoroolefin com amine to produce a reaction product having a relatively high prises 2,3,3,3-tetrafluoropropene. boiling point and/or an ammonium salt. The amine reactive 0017. A sufficient amount of an amine is added to the impurity can then be removed from the desired composition mixture to form a combination comprising the second hydrof without significant yield loss. This method is particularly luoroolefin and a reaction product of the first hydrofluoroole advantageous when separating hydrofluoroolefins having fin and the amine. Thereafter, the reaction product is sepa pinch points or azeotropic compositions. For example, this rated from the combination. Often the reaction product is a method is especially useful in preferentially reacting a HFO salt formed by reacting the first hydrofluoroolefin and the 1225ye(Z) impurity in a HFO-1234yfproduct stream because amine. it has been found that HFO-1225ye is about 500 times more 0018 Amines useful in the present invention include pri reactive with amines than HFO-1234yf. mary, secondary and tertiary amines. The reactivity of amines 0012. Accordingly, provided is A process for preparing a with the undesirable hydrofluoroolefin is generally hydrofluoroolefin comprising (a) providing a first composi primary>secondary>tertiary. The reactivity of the amine also tion having a first hydrofluoroolefin and a second hydrofluo depends upon the steric hindrance. The more hindered the roolefin; (b) contacting said composition with an amine to amine the less reactive it will be. For example, trimethy produce a second composition comprising said second lamine is more reactive than diisopropyl ethylamine. Accord hydrofluoroolefin and a reaction product derived from a reac ingly, most preferred amines are not sterically hindered. tion between said amine and said first hydrofluorocarbon, 0019 Preferably the boiling point of the amine is at least wherein said reaction product is an ammonium salt and/or has about 20° C. greater than the boiling point of the second a boiling point higher than the boiling point of said second hydrofluoroolefin. Preferably the first hydrofluoroolefin is hydrofluoroolefin; and (c) separating said reaction product about 100 or more times more reactive with the amine than the from second composition to produce a purified product, second hydrofluoroolefin. More preferably the first hydrof wherein said purified product has a higher concentration of luoroolefin is about 500 or more times more reactive with the said second hydrofluoroolefin compared to said second com amine than the second hydrofluoroolefin. The determination position. of reaction rates is well known to the skilled artisan. See 0013 Also provided is a process for purifying a hydrof Chemical luoroolefin product stream comprising: (a) providing a first 0020 Reaction Engineering. Third Edition; by Octave composition comprising a tetrafluoropropene and a pen Levenspiel; John Wiley & Sons. 1999; chapter 2 at pages tafluoropropene, wherein said tetrafluoropropene and said 13-33, which is incorporated herein by reference. pentafluoropropene are present in amounts to form an azeo 0021 Non-limiting examples of useful amines include at trope-like mixture; (b) contacting said composition with an least one of propyl amine, n-butyl amine, ethylenediamine, amine to produce a non-azeotrope-like product comprising n-octylamine, aniline, cyclohexylamine, benzylamine, dim said tetrafluoropropene and a reaction product derived from a ethylamine, diethylamine, dibutylamine, dibenzylamine, reaction between said amine and said pentafluoropropane; morpholine, N-methyl aniline, methylbenzylamine, piperi and (c) separating said reaction product from said tetrafluo dine, pyrrole, pyrrolidine, pyrrolidinone, piperazine, mor ropropene to produce a purified product having a higher con pholine, piperidine, pyrrole, pyrrolidine, N-alkylmorpho centration of said first hydrofluoroolefin compared to said lines, N-alkylalkanolamines, N,N-dialkylcyclohexylamines, second composition. and alkylamines where the alkyl groups are methyl, ethyl, 0014. Also provided is a process for separating the com propyl, butyl and isomeric forms thereof, triethylamine, ponents of an azeotrope-like composition comprising: (a) diisopropylethylamine, triethylenediamine, tetramethyleth providing a first composition comprising an azeotrope-like ylenediamine, bis(2-dimethylaminoethyl)ether, triethy mixture of 2,3,3,3-tetrafluoropropene and 1,1,1,2,3-pen lamine, tripropylamine, tributylamine, triamylamine, pyri tafluoropropane; and (b) contacting said mixture with an dine, quinoline, dimethylpiperazine, piperazine, N.N- amine to produce a second composition, wherein said second dimethylcycolhexylamine, N-ethylmorpholine, composition is essentially free of azeotrope-like mixtures. 2-methylpiperazine, N,N-dimethylethanolamine, tetrameth ylpropanediamine, methyltriethylenediamine, N.N.N',N', BRIEF DESCRIPTION OF THE DRAWING N"-pentamethyldiethylene triamine, and mixtures thereof. 0022. In certain preferred embodiments, the amine is 0015 FIG. 1 shows an example of an apparatus useful for added to the mixture in an amount of up to about a 1:1 mole the continuous removal of an amine reactive impurity. ratio with the amount of the first hydrofluoroolefin. Once the amine has reacted with the first hydrofluoroolefin, it will DESCRIPTION OF THE INVENTION create a reaction product which is often an ammonium salt and/or a higher boiling reaction product. These salts and/or a 0016. In the production of hydrofluoroolefins it is com higher boiling reaction products typically can easily be sepa mon for the desired hydrofluoroolefin to contain minor rated from the desired second hydrofluoroolefin in the com amounts of other, undesired hydrofluoroolefins as impurities bination by at least one of evaporation, distillation, absorption to be removed. Removal is often difficult due to the close or solvent extraction, which are well known techniques to the boiling points of the hydrofluoroolefin. Thus the inventive skilled artisan. process separates a first hydrofluoroolefin from a second 0023 The resulting salts and/or higher boiling reaction hydrofluoroolefin in a mixture comprising a first hydrofluo products also can easily be separated from the amine. The roolefin and a second hydrofluoroolefin, in which the first amine can be purified by simple evaporation and Subsequent hydrofluoroolefin is preferentially more reactive with an condensation of the amine which leaves the salt and/or a amine than the second hydrofluoroolefin. In a preferred higher boiling reaction product behind. The regenerated embodiment, the first hydrofluoroolefin comprises 1,2,3,3,3- amine can once again be used to react with additional impu US 2010/0193347 A1 Aug. 5, 2010 rity. In a preferred embodiment, the process further comprises by simple evaporation of the morpholine. The purified mor the Subsequent step of recycling the amine back to the amine pholine can then be recycled to react with additional HFO reaction step b). 1225ye(Z). 0024. An example of a continuous process which would allow for the amine reactive impurity to be removed is shown TABLE 1 in FIG. 1. From FIG. 1 it can be seen that it is preferable to have an amine that boils at least 20°C. higher than the product Removal of HFO-1225 ye(Z) from HFO-1234yfusing Morpholine being purified in order to not have any amine appear in the 1225ye(Z) Morpholine Conductivity product stream. The amine purification and product purifica Sample ppm Scm tion columns could be a simple flash tanks or distillation/ Initial 935 O.OO absorption columns. Material 0025. The following non-limiting examples serve to illus 1st Pass 589 trate the invention. 2nd Pass 499 3rd Pass 470 4th Pass 472 O.O3 Example 1 Fresh Morpholine

Relative Reactivity of HFO-1234yf and HFO 5th Pass 295 1225ye Toward an Amine 0026. A glass pressure reactor was charged with a solution 0029 While the present invention has been particularly of 1.735+0.005 g of N.N.N',N',N'-pentamethyldiethylene shown and described with reference to preferred embodi triamine (MeNCHCHNMeCHCHNMe) in 50.0 g of a ments, it will be readily appreciated by those of ordinary skill polyol based solvent. The olefin (HFO-1234yf, 3.09 g, 0.027 in the art that various changes and modifications may be made mol or HFO-1225ye(Z), 3.47 g., 0.026 mol) was then added without departing from the spirit and scope of the invention. and the mixture stirred with heating to 130°F. by means of an It is intended that the claims be interpreted to cover the oil bath. Samples (2-3 mL) were taken periodically. The dis disclosed embodiment, those alternatives which have been Solved olefin in the sample was removed under vacuum and discussed above and all equivalents thereto. the residue analyzed for inorganic fluoride as an indication of What is claimed is: the extent of reaction. 1. A process for preparing a hydrofluoroolefin comprising: a. providing a first composition having a first hydrofluo roolefin and a second hydrofluoroolefin; b. contacting said composition with an amine to produce a Olefin Time (hours) ppm Fluoride second composition comprising said second hydrofluo HFO-1234yf 19.0 3 roolefin and a reaction product derived from a reaction 67.75 11 between said amine and said first hydrofluorocarbon, 163 31 HFO-1225ye(Z) 2O.S 2936 wherein said reaction product is an ammonium salt and/ 46.0 4827 or has a boiling point higher than the boiling point of said 71.75 7151 second hydrofluoroolefin; and c. separating said reaction product from second composi tion to produce a purified product, wherein said purified 0027. When ppm fluoride is plotted against time for each product has a higher concentration of said second olefin, a straight line is obtained, the slopes of which show hydrofluoroolefin compared to said second composi that in this test, HFO-1225ye(Z) is over 500 times more tion. reactive than HFO-1234yf. 2. The process of claim 1 wherein the first hydrofluoroole fin is about 100 or more times more reactive with the amine Example 2 than the second hydrofluoroolefin. Removal of HFO-1225ye(Z) from HFO-1234yf 3. The process of claim 1 wherein the first hydrofluoroole Using Morpholine fin is about 500 or more times more reactive with the amine than the second hydrofluoroolefin. 0028. A sample of HFO-1234yf which initially contained 4. The process of claim 1 wherein the reaction product is 935 ppm. HFO-1225ye(Z) was bubbled through morpholine separated from the combination by at least one of evapora at 23°C. and ambient pressure. As the olefin exited the bub tion, distillation, absorption or solvent extraction. bler it was collected in a cylinder cooled by dry ice. The 5. The process of claim 1 wherein the first hydrofluoroole HFO-1225ye(Z) content of the collected material was then fin comprises at least one 1,2,3,3,3-pentafluoropropene. analyzed and again bubbled through the morpholine. The 6. The process of claim 1 wherein the second hydrofluo olefin was bubbled through the same sample of morpholine 4 roolefin comprises 2,3,3,3-tetrafluoropropene. consecutive times. A fresh morpholine sample was then 7. The process of claim 1 wherein the first hydrofluoroole placed in the bubbler and the sample was passed through for fin comprises 1.2.3,3,3-pentafluoropropene and wherein the a 5' time. The results of the HFO-1225ye(Z) analysis indi second hydrofluoroolefin comprises 2,3,3,3-tetrafluoropro cate that the morpholine is able reduce the HFO-1225ye(Z) pene. concentration by nearly /2. The electrical conductivity of the 8. The process of claim 1 wherein the amine has a boiling morpholine was also measured before and after the HFO point that is at least about 20°C. higher than the boiling point 1225ye(Z) collection. The increase in the electrical conduc of the second hydrofluoroolefin. tivity indicates that a salt has formed from the olefin and 9. The process of claim 1 wherein the amine comprises at morpholine. The salt can be separated from the morpholine least one of propyl amine, n-butyl amine, ethylenediamine, US 2010/0193347 A1 Aug. 5, 2010

n-octylamine, aniline, cyclohexylamine, benzylamine, dim c. separating said reaction product from said tetrafluoro ethylamine, diethylamine, dibutylamine, dibenzylamine, propene to produce a purified product having a higher morpholine, N-methyl aniline, methylbenzylamine, piperi concentration of said first hydrofluoroolefin compared dine, pyrrole, pyrrolidine, pyrrolidinone, piperazine, mor to said second composition. 12. The process of claim 11 wherein said a non-azeotrope pholine, piperidine, pyrrole, pyrrolidine, N-alkylmorpho like product comprises a majority of said tetrafluoropropene lines, N-alkylalkanolamines, N,N-dialkylcyclohexylamines, from said first composition. and alkylamines where the alkyl groups are methyl, ethyl, 13. The process of claim 11 wherein said purified product propyl, butyl and isomeric forms thereof, triethylamine, comprises less pentafluoropropene compared to said first diisopropylethylamine, triethylenediamine, tetramethyleth composition. ylenediamine, bis(2-dimethylaminoethyl)ether, triethy 14. The process of claim 11 wherein said first composition lamine, tripropylamine, tributylamine, triamylamine, pyri is provided as a feed stream. dine, quinoline, dimethylpiperazine, piperazine, N.N- 15. The process of claim 11 wherein said purified product dimethylcyclohexylamine, N-ethylmorpholine, is provided as a process stream. 2-methylpiperazine, N,N-dimethylethanolamine, tetrameth 16. The process of claim 11 wherein said non-azeotrope ylpropanediamine, methyltriethylenediamine, N.N.N',N', like product further comprising at least a portion of said N"-pentamethyldiethylene triamine, and mixtures thereof. amine from step (b) and wherein said process further com 10. The process of claim 1 wherein said contacting involves prises adding said amine to the first composition in an amount of up d. Separating said amine from said non-azeotrope-like to about a 1:1 moleratio relative to the first hydrofluoroolefin. product and recycling said amine so separated to step (b). 11. A process for purifying a hydrofluoroolefin product 17. A process for separating the components of an azeo stream comprising: trope-like composition comprising: a. providing a first composition comprising a tetrafluoro a. providing a first composition comprising an azeotrope propene and a pentafluoropropene, wherein said tet like mixture of 2,3,3,3-tetrafluoropropene and 1,1,1,2, rafluoropropene and said pentafluoropropene are 3-pentafluoropropane; and present in amounts to form an azeotrope-like mixture; b. contacting said mixture with an amine to produce a b. contacting said composition with an amine to produce a second composition, wherein said second composition non-azeotrope-like product comprising said tetrafluoro is essentially free of azeotrope-like mixtures. propene and a reaction product derived from a reaction between said amine and said pentafluoropropane; and c c c c c