METHODS OF HANDLING CHLORINATED COMPOUNDS USED FOR MANUFACTURING HFO-1234yf

Abstract

This invention provides methods for handling, storing and/or transporting reactive chlorinated compounds such as 1230xa whereby decomposition reactions are reduced or eliminated by employing one or more anti-decomposition techniques selected from the group consisting of: (a) providing a 1230xa supply with little or no moisture, HCl, and/or metallic ions, (b) providing a storage and/or transport tank preferably lined and/or coated with one or more suitable materials, (c) transferring 1230xa, preferably stabilized 1230xa, into a storage and/or transportation tank in such a way that no exposure of the 1230xa to air occurs, (d) handling, storing, and/or transporting 1230xa under the protection of a dried inert gas such as nitrogen, (e) optionally providing a device that can remove any HCl generated during the storage and/or transportation of 1230xa; and (f) combinations of two or more of these anti-decomposition techniques.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. Provisional Patent Application Ser. No. 61/760,332 filed Feb. 4, 2012, the disclosure of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

The compound 2,3,3,3-tetrafluoropropene (HFO-1234yf) is a low GWP molecule, which can be used as refrigerant, blowing agent, cleaning agent, as well as a monomer of macromolecule compounds. As disclosed in U.S. Pat. No. 8,058,486, a manufacturing process for 1234yf that uses one of three chlorinated compounds, namely, 1,1,2,3-tetrachloropropene (1230xa), 2,3,3,3-tetrachloropropene (1230xf), and 1,1,1,2,3-pentachloropropane (240db) as starting raw material, includes the following three steps:

• • 1) 1230xa (or 1230xf or 240db)+HF->1233xf+HCl in a vapor phase reactor charged with a solid catalyst,
  • 2) 1232xf+HF->244bb in a liquid phase reactor charged with a liquid catalyst, and
  • 3) 244bb->1234yf in a vapor phase reactor.

These feed materials are usually stored in containers made from plastic, carbon steel, and/or stainless steel. Chlorinated compounds such as 1230xa, 1230xf, and 240db, are known to decompose under certain conditions. Those conditions include the presence of air (oxygen), moisture and metal components. While not wishing to be bound to any theory, the present inventors believe that 1230xa, 1230xf, and 240db decomposition occurs due to one or more of the following factors:

• • (i) atmospheric oxidation of these chlorinated compounds occurs in the presence of oxygen (e.g., included in air), resulting in the formation of phosgenes;
  • (ii) hydrolysis of these chlorinated compounds takes place in the presence of moisture, resulting in the formation of HCl and organic compound(s);
  • (iii) dehydrochlorination of these chlorinated compounds might occur in the presence of metallic salts, resulting in the formation of HCl and organic compound; and
  • (iv) dimerization of these chlorinated compounds might take place in the presence of metal components, resulting in the formation of dimers (or oligomers) and metallic chlorides.

The detrimental impacts resulting from these potential decomposition reactions include purity drop due to the conversion of these chlorinated compounds to other organic compounds and accelerated corrosion of storage containers due to HCl formation. Thus, there is a continuing need for means by which these chlorinated compounds can be suitably handled, stored and/or transported, wherein little or no degradation or decomposition occurs.

SUMMARY OF THE INVENTION

The solution to the decomposition problem of chlorinated compounds including 1230xa, 1230xf and/or 240db as detailed herein comprises the implementation of one or more of the following anti-decomposition techniques which reduce and/or prevent the decomposition of these chlorinated compounds and similar chlorinated compounds that decompose under similar conditions. In certain embodiments, two or more, preferably three or more, and more preferably, all of these techniques are employed. While 1230xa is specifically mentioned below, other chlorinated compounds such as 1230xf, 1230za, trans-1230xd, cis-1230xd, 1240za, 1240zf, 250fb, and 240db, can also be treated in a like manner to reduce and/or prevent decomposition:

• • (1) provide a 1230xa feed supply with little or no moisture, HCl, and metallic ions,
  • (2) provide a storage and/or transport tank preferably lined and/or coated with suitable materials,
  • (3) transfer 1230xa, optionally stabilized 1230xa, into a storage and/or transportation tank in such a way that no exposure of 1230xa to air occurs,
  • (4) handle, store, and/or transport 1230xa under the protection of dried nitrogen, and
  • (5) optionally provide a method and/or device that can remove any HCl generated during storage and/or transportation.

It should be appreciated by those persons having ordinary skill in the art(s) to which the present invention relates that any of the features described herein in respect of any particular aspect and/or embodiment of the present invention can be combined with one or more of any of the other features of any other aspects and/or embodiments of the present invention described herein, with modifications as appropriate to ensure compatibility of the combinations. Such combinations are considered to be part of the present invention contemplated by this disclosure.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.

DETAILED DESCRIPTION OF THE INVENTION

As described above, the present invention provides methods for handling, storing and/or transporting 1230xa, and similar reactive chlorinated compounds, whereby decomposition reactions including a purity drop due to conversion to other organic compounds and accelerated corrosion of containers due to HCl formation are reduced or eliminated by employing one or more of the anti-decomposition techniques selected from the group consisting of: (1) providing a 1230xa supply with little or no moisture, HCl, and/or metallic ions, (2) providing a storage and/or transport tank preferably lined and/or coated with one or more suitable materials, (3) transferring 1230xa, preferably stabilized 1230xa, into a storage and/or transportation tank in such a way that no exposure of the 1230xa to air occurs, (4) handling, storing, and/or transporting 1230xa under the protection of a dried inert gas such as nitrogen, (5) optionally providing a device that can remove any HCl generated during the storage and/or transportation of 1230xa; and (6) combinations of two or more of these anti-decomposition techniques.

One embodiment of the present invention can be generally described as a method for handling, storing, and/or transporting 1230xa. Step (1) above thus provides a 1230xa feed supply with little or no moisture, HCl, and/or metallic ions therein. In this 1230xa feedstock the moisture level is generally lower than 100 ppm, preferably 50 ppm, and more preferably 25 ppm. In this 1230xa feedstock the HCl level is generally lower than 200 ppm, preferably 50 ppm, and more preferably 10 ppm. In this 1230xa feedstock the metallic ion content, e.g., iron ion content, is generally lower than 10 ppm, preferably 5 ppm, and more preferably 2 ppm. Various known methods can be used to achieve each of these values.

Any conventional technique can be used to remove moisture. Non-limiting techniques include distillation, and/or absorption using desiccants, and/or the like. Distillation can be operated at atmospheric pressure, super-atmospheric pressure or under vacuum and can be performed using standard distillation methods for separating two compounds. Another method of removing the moisture from 1230xa is by the use of desiccants, whereby the desiccant is in contact with 1230xa for sufficient amount of time to reduce the moisture content. While various desiccants can be used in a variety of ways, in certain embodiments 1230xa is dried in pre-packaged desiccant in continuous mode. Non-limiting desiccants include silica gel, activated charcoal, calcium sulfate, calcium chloride, montmorillonite clay, and various molecular sieves. The moisture content present in 1230xa is measured by conventional means, such as Karl Fischer titration and the like.

Any techniques known in the art can be used to remove HCl. In one preferred embodiment, HCl is removed by distillation. Single column or multiple columns may be used. Distillation can be operated at atmospheric pressure, super-atmospheric pressure or under vacuum and can be performed using standard distillation methods for separating two compounds. The amount of HCl present in 1230xa is determined using standard techniques known in the art. For example, the amount of HCl present is determined by acid-base titration or IC (Ion Chromatography).

Any techniques known in the art can be used to remove ionic iron. In one embodiment, it is removed by distillation. Single column or multiple columns may be used. Distillation can be operated at atmospheric pressure, super-atmospheric pressure or under vacuum and can be performed using standard distillation methods for separating two compounds. The amount of ionic iron present in 1230xa is determined using standard techniques known in the art. For example, the amount of iron present is determined by ICP (Inductive Coupled Plasma).

Another embodiment of the present invention can be generally described as a storage and/or transport tank, preferably lined/coated with suitable non-reactive materials. Step (2) above thus provides a storage/transport tank preferably lined/coated with suitable materials, Carbon steel, stainless steel and plastic can be used to make the desired storage and/or transport tank. However, a carbon steel tank internally lined and/or coated with suitable material is preferred. Non-limiting examples of suitable lining and/or coating materials include glass, ceramic, a phenolic or epoxy resin liner such as Plasite 3070 (available from Carboline Company), Plasite 9573 (available from Carboline Company), and Phenicon HS Flake Filled (available from Sherwin Williams), and the like.

Yet another embodiment of the present invention can be generally described as a method of transfer of 1230xa such that decomposition is minimized or eliminated. Step (3) above thus provides a method for the transfer of 1230xa, optionally stabilized 1230xa into said storage/transportation tank in such a way that little or no exposure of 1230xa to air occurs. Before making any 1230xa transfer, all equipment and the storage and/or transportation tank are subject to an effective purge with a dried inert gas (e.g., nitrogen) to displace air. Optionally but preferably, 1230xa is added with a stabilizer before being transferred or transported. Non-limiting examples include, but are not limited to, diisopropylamine, triethylamine, 4-tert-Amylphenol, 4-methoxyphenol, and their combinations. The amount of stabilizer(s) present in 1230xa can range from about 1 to about 1000 ppm, preferably from about 2 to about 100 ppm, more preferably from about 3 to about 50 ppm, and most preferably from about 4 to about 20 ppm.

Another embodiment of the present invention can be generally described as a method of protecting 1230xa such that decomposition is minimized or eliminated. Step (4) above is similar to Step (3), wherein the storage and/or transport of 1230xa takes place under the protection of an excess amount of dried nitrogen. In this embodiment, after the 1230xa is transferred into a storage and/or transportation tank, the tank is pressurized with dried nitrogen and is then sealed (closed to the atmosphere) to prevent air and/or moisture from entering the tank.

Yet another embodiment of the present invention can be generally described as a method of protecting 1230xa such that decomposition is minimized or eliminated. Step (5) above makes use of a device and/or method that is effective in removing any HCl generated during the storage and/or transportation of 1230xa. One way of removing HCl is by having either constant or periodical purge of nitrogen and/or any other inert gas through a column loaded with solid basic sorbent before venting. Non-limiting solid sorbents include, but are not limited to, alumina, calcium carbonate, sodium carbonate, sodium aluminate, and the like.

EXAMPLES

The following examples provide test data for various materials exposed to 1230xa.

Example 1

This example illustrates the effectiveness of 3A molecular sieves for removing moisture from 1230xa feed. The 1230xa used in Example 1 had a purity of 99.2 GC (gas chromatogram) area % and contained 100 ppm of moisture. 5 ppm of di-isopropyl amine was added into 1230xa as a stabilizer. The 1230xa feed was passed through a 2″ ID column loaded with 2 liters of 3A molecular sieves at rate of 1.0 lb/h and sample was taken from a sampling port after drying column. Moisture level was determined to be 12 ppm by using Mitsubishi Moisture Meter (Model CA-100), indicating 3A molecular sieve is an effective drying agent for 1230xa.

Example 2

Three materials were evaluated as a possible MOC (material of construction) for a shipping and/or storage container for 1230xa. The materials were carbon steel, stainless steel, and carbon steel coated with Plasite 3070. Four glass tubes were filled with the same amount of solution containing 1230xa and 5 ppm of di-isopropyl amine. Carbon steel, stainless steel, and Plasite 3070 coupons were placed into tube containing solution of 1230xa-di-isopropyl amine and the tubes were then closed. The fourth tube (blank) contained no coupon. All transfers were done under atmosphere of nitrogen. All coupons were 5″ long, 1″ wide, and ⅛″ thick. The tubes were then transferred to an oven kept at 50° C. Periodical visual observations were made and photographs of the tubes were taken. After one week at 50° C., the 1230xa solution in the tube containing carbon steel coupon turned brown-yellow and corrosion of the carbon steel coupon was noted, indicating the occurrence of chemical reactions such as breakdown of 1230xa. After 4 weeks at 50° C., the 1230xa solution in the tube containing stainless steel coupon was pale yellow, however, no corrosion of the stainless steel coupon was noted. After 90 days at 50° C., the 1230xa solution in the tube containing Plasite 3070 coupon remained as clear visually as the blank sample. These results indicate that stainless steel can be a suitable MOC for vessels for transporting 1230xa and that Plasite 3070 can serve as a liner or coating for 1230xa storage tanks.

As used herein, the singular forms “a”, “an” and “the” include plural unless the context clearly dictates otherwise. Moreover, when an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range.

It should be understood that the foregoing description is only illustrative of the present invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims.

Claims

1. A method for handling, storing and/or transporting reactive chlorinated compounds selected from the group consisting of 1230xa, 1230xf, 1230za, trans-1230xd, cis-1230xd, 1240za, 1240zf, 250fb, and 240db, whereby decomposition reactions including a purity drop due to conversion of the reactive compounds to other organic compounds and accelerated corrosion of containers due to HCl formation are reduced or eliminated by employing one or more anti-decomposition techniques.

2. The method of claim 1, wherein the reactive compound is 1230xa.

3. The method of claim 1, wherein the reactive compound is 1230xf.

4. The method of claim 1, wherein the reactive compound is 240db.

5. The method of claim 1, wherein the anti-decomposition techniques are selected from the group consisting of:

(a) providing a reactive compound supply with little or no moisture, HCl, and/or metallic ions,

(b) providing a storage and/or transport tank preferably lined and/or coated with one or more suitable materials,

(c) transferring the reactive compounds into a storage and/or transportation tank in such a way that no exposure of the compounds to air occurs,

(d) handling, storing, and/or transporting the reactive compounds under the protection of a dried inert gas,

(e) optionally providing a device that can remove any HCl generated during the storage and/or transportation of the reactive compounds; and

(f) combinations of two or more of these anti-decomposition techniques.

6. The method of claim 5, wherein the supply of the reactive compound includes a moisture level lower than 100 ppm.

7. The method of claim 5, wherein the supply of the reactive compound includes an HCl level lower than 200 ppm.

8. The method of claim 5, wherein the supply of the reactive compound includes a metallic ion content lower than 10 ppm.

9. A method for handling, storing and/or transporting 1230xa, whereby decomposition reactions including a purity drop due to 1230xa conversion to other organic compounds and accelerated corrosion of containers due to HCl formation are reduced or eliminated by employing one or more 1230xa anti-decomposition techniques selected from the group consisting of:

(a) providing a 1230xa supply with little or no moisture, HCl, and/or metallic ions,

(b) providing a storage and/or transport tank preferably lined and/or coated with one or more suitable materials,

(c) transferring 1230xa into a storage and/or transportation tank in such a way that little or no exposure of the 1230xa to air occurs,

(d) handling, storing, and/or transporting 1230xa under the protection of a dried inert gas,

(e) optionally providing a device that can remove any HCl generated during the storage and/or transportation of 1230xa; and

(f) combinations of two or more of these anti-decomposition techniques.

10. The method of claim 9, wherein the supply of 1230xa includes a moisture level lower than 100 ppm.

11. The method of claim 9, wherein the supply of 1230xa includes a moisture level lower than 50 ppm.

12. The method of claim 9, wherein the supply of 1230xa includes a moisture level lower than 25 ppm.

13. The method of claim 9, wherein the supply of 1230xa includes an HCl level lower than 200 ppm.

14. The method of claim 9, wherein the supply of 1230xa includes an HCl level lower than 50 ppm.

15. The method of claim 9, wherein the supply of 1230xa includes an HCl level lower than 10 ppm.

16. The method of claim 9, wherein the supply of 1230xa includes a metallic ion content lower than 10 ppm.

17. The method of claim 9, wherein the supply of 1230xa includes a metallic ion content lower than 5 ppm.

18. The method of claim 9, wherein the supply of 1230xa includes a metallic ion content lower than 1 ppm.

19. The method of claim 9, wherein the inert gas comprises nitrogen.

20. The method of claim 9, wherein the metallic ions comprise iron.