Process for reducing the total acidity of refrigerating compositions

Abstract

The present invention relates to a process for reducing the total acidity of refrigerating compositions comprising at least one refrigerant with at least one lubricant, said process comprising at least one stage of bringing said composition into contact with at least one zeolitic adsorbent based on powder formed of zeolite(s) or on agglomerates formed of zeolite(s).

Claims

1. A process for limiting or controlling the increase in the total acid number in a refrigerating composition comprising at least one refrigerant and at least one lubricant, said process comprising a stage of bringing said refrigerating composition into contact with at least one zeolitic adsorbent, wherein the at least one zeolitic adsorbent is free of metal impregnation and the at least one zeolitic adsorbent is based on zeolite(s) A exchanged with potassium, the degree of exchange of which is between 50% and 70% (reported as molar equivalents) of all of the exchangeable cationic sites, wherein the at least one zeolitic adsorbent is present in an effective amount to limit or reduce the total acid number of the lubricant and the effective amount is about 40 mg to about 1000 mg per 5 g of lubricant.

2. The process as claimed in claim 1, wherein the at least one zeolitic adsorbent is chosen from a mixture of zeolite A type and one or both of zeolites of faujasite type and zeolites Y.

3. The process as claimed in claim 1, wherein the at least one zeolitic adsorbent is chosen from a mixture of zeolites of zeolite A type and zeolites of faujasite type.

4. A process for limiting or controlling the increase in the total acid number in a refrigerating composition comprising at least one refrigerant and at least one lubricant, said process comprising a stage of bringing said refrigerating composition into contact with at least one zeolitic adsorbent, in the form of a powder formed of zeolite(s) or of agglomerate(s) formed of zeolite(s), wherein the at least one zeolitic adsorbent is free of metal impregnation and the at least one zeolitic adsorbent is based on zeolite(s) A exchanged with potassium, the degree of exchange of which is between 50% and 70% (reported as molar equivalents) of all of the exchangeable cationic sites, wherein the at least one zeolitic adsorbent is present in an effective amount to limit or reduce the total acid number of the lubricant and the effective amount is about 40 mg to about 1000 mg per 5 g of lubricant.

5. The process of claim 2, wherein the at least one zeolitic adsorbent is present in the effective amount to limit or reduce the total acid number (TAN-14 day) of the lubricant such that the total acid number is maintained at or below 2.7 mg KOH/g.

6. The process as claimed in claim 1, wherein the at least one lubricant is chosen from the lubricants employed in the fields of refrigeration and air conditioning for air or gas compressors and for refrigerating machine compressors and more generally for all dynamic or static refrigeration systems.

7. The process as claimed in claim 1, wherein the at least one refrigerant comprises fluorinated compounds.

8. The process as claimed in claim 1, wherein the at least one lubricant is selected from the group consisting of polyalkylene glycols (PAGs), polyol esters (POEs), polyvinyl ethers (PVEs), and combinations thereof.

9. The process as claimed in claim 1, wherein the at least one lubricant is a lubricant used in refrigeration systems and comprises at least one refrigerant chosen from hydrofluoroolefins (HFOs) and hydrofluorocarbons (HFCs).

10. The process as claimed in claim 1, wherein the at least one lubricant is a mixture of a lubricant and of a refrigerant, said mixture being chosen from PAG lubricant and 1,1,1,2-tetrafluoroethane, PAG lubricant and 2,3,3,3-tetrafluoropropene, POE lubricant and 1,1,1,2-tetrafluoroethane, POE lubricant and 2,3,3,3-tetrafluoropropene, PVE lubricant and 1,1,2-tetrafluoroethane, and PVE lubricant and 2,3,3,3-tetrafluoropropene, preferably comprising PAG and 1,1,1,2-tetrafluoroethane, PAG and 2,3,3,3-tetrafluoropropene, PVE and 1,1,1,2-tetrafluoroethane and PVE and 2,3,3,3-tetrafluoropropene.

11. The process as claimed in claim 1, wherein the lubricating composition is employed in refrigeration systems, motor vehicle or domestic air conditioning systems, heat pumps, electric transformers or metal cutting and milling instruments.

12. The process of claim 1, wherein the at least one zeolitic adsorbent is selected from the group consisting of zeolite 3A powder and agglomerates based on zeolite A powder, wherein the potassium exchange is carried out on the powder, the agglomerate, or both.

13. A process for limiting or controlling the increase in the total acid number in a refrigerating composition comprising at least one refrigerant and at least one lubricant, said process comprising a stage of bringing said refrigerating composition into contact with at least one zeolitic adsorbent, wherein the at least one zeolitic adsorbent is free of metal impregnation and the at least one zeolitic adsorbent is based on zeolite(s) A exchanged with potassium, the degree of exchange of which is between 50% and 70% (reported as molar equivalents) of all of the exchangeable cationic sites, and at least one other alkali or alkaline earth metal, the degree of exchange of which is between 30% and 50% (reported as molar equivalents) of all of the exchangeable cationic sites.

14. The process of claim 13, wherein the at least one other alkali or alkaline earth metal is sodium.

15. The process of claim 13, wherein the at least one zeolitic adsorbent is present in an effective amount to limit or reduce the total acid number of the lubricant such that the total acid number (TAN-14 day) is maintained at or below 2.7 mg KOH/g.

16. The process of claim 7, wherein the at least one refrigerant is selected from the group consisting of hydrofluoroolefins (HFOs), hydrofluorocarbons (HFCs), and combinations thereof.

17. The process of claim 16, wherein the at least one refrigerant is selected from the group consisting of tetrafluoroethanes, tetrafluoropropenes, and combinations thereof in all proportions.

18. The process of claim 17, wherein the at least one refrigerant is selected from the group consisting of 1,1,1,2-tetrafluoroethane (R-134a), 2,3,3,3-tetrafluoropropene (HFO-1234yf), and combinations thereof.

19. The process of claim 8, wherein the at least one lubricant is selected from the group consisting of PAGs, PVEs, and combinations thereof.

20. The process of claim 9, wherein the at least one refrigerant is selected from the group consisting of tetrafluoroethanes, tetrafluoropropenes, and combinations thereof.

21. The process of claim 20, wherein the at least one refrigerant is selected from the group consisting of 1,1,1,2-tetrafluoroethane, 2,3,3,3-tetrafluoropropene, and combinations thereof.

22. The process of claim wherein the at least one zeolitic adsorbent is present in an effective amount to limit or reduce the total acid number of the lubricant and the effective amount is about 40 mg to about 1000 mg per 5 g of lubricant.

23. The process of claim 1, wherein the at least one zeolitic adsorbent is based on zeolite(s) 3A.

24. The process of claim 1, wherein the at least one zeolitic adsorbent is based on zeolite(s) 4A.

25. The process of claim 1, wherein the at least one zeolitic adsorbent is based on zeolite(s) 5A.

26. The process of claim 1, wherein the at least one zeolitic adsorbent provides for a total acid number (TAN-14 day) in the refrigerating composition of 2.7 or less (mg KOH/g).

27. The process of claim 26, wherein the TAN-14 day value is 0.4 to 2.7 (mg KOH/g).

28. A process for limiting or controlling the increase in the total acid number in a refrigerating composition comprising at least one refrigerant and at least one lubricant, said process comprising a stage of bringing said refrigerating composition into contact with at least one zeolitic adsorbent, wherein the at least one zeolitic adsorbent is free of metal impregnation and the at least one zeolitic adsorbent is based on zeolite(s) A exchanged with potassium, the degree of exchange of which is between 50% and 70% (reported as molar equivalents) of all of the exchangeable cationic sites, wherein the at least one zeolitic adsorbent is present in an effective amount to limit or reduce the total acid number (TAN-14 day) of the lubricant such that the total acid number is maintained at or below 2.7 mg KOH/g.

Description

EXAMPLE 1

Thermal Stability Tests

(1) The thermal stability tests are carried out on compositions for refrigerating systems, that is to say comprising a refrigerant and lubricant, according to the standard ASHRAE 97-2007: Sealed glass tube method to test the chemical stability of materials for use within refrigerant systems.

(2) The test conditions are as follows: weight of refrigerant: 2.2 g weight of lubricant: 5 g weight of zeolitic adsorbent: 40 to 1000 mg temperature: 200 C. duration: 14 days

(3) The zeolitic adsorbent and the lubricant are introduced into a glass tube with a volume of 42.2 ml. The tube is subsequently placed under vacuum and then the refrigerant is added. The tube is then sealed in order to hermetically close it and is placed in an oven at 200 C. for 14 days.

(4) Various analyses are carried out at the end of the test: The gas phase is recovered in order to be analyzed by gas chromatography: the main impurities are identified by GC/MS (gas chromatography/mass spectrometry). Impurities coming from the refrigerant and those coming from the lubricant can thus be grouped together. The lubricant is analyzed: color (by spectrocolorimetry, Labomat Dr Lange Lico220 Model MLG131), water content (by Karl Fischer coulometric titration, Mettler DL37) and total acid number (by quantitative determination with 0.01N methanolic potassium hydroxide solution).

(5) The lubricants used in the tests are commercial PAG and POE lubricants: PAG ND8 and POE Ze-GLES RB68, sold respectively by Nippon Denso and Nippon Oil.

(6) The refrigerants used for these tests are either HFO-1234yf or R-134a.

(7) The results shown in the following table 1 are obtained with HFO-1234yf and, as lubricant, the commercial PAG lubricant PAG ND8 and various zeolitic adsorbents supplied by CECA S.A.

(8) TABLE-US-00001 TABLE 1 Type of Amount of Adsorbent adsorbent adsorbent (mg) TAN (mg KOH/g) None 4.7 Siliporite NK30 3A 200 1.7 AP Powder Siliporite NK30 3A 1000 2.6 AP Powder Siliporite NK30 3A 200 1.5 AP Powder overexchanged Siliporite NK30 3A 1000 2.5 AP Powder overexchanged Siliporite NK30 3A 1000 1.6 Beads (Static) Siliporite NK10 4A 1000 2.7 AP Powder Siliporite NK20 5A 1000 2.4 Siliporite G5 XP 10A 1000 2.7 Powder

(9) These first results show that the presence of zeolitic adsorbents in the refrigerating compositions makes it possible to considerably reduce the TAN of the lubricants.

(10) These results are confirmed, in the following table 2, with the tests carried out with compositions comprising R-134a and, as lubricant, the lubricant PAG ND8 and various zeolitic adsorbents supplied by CECA S.A.

(11) TABLE-US-00002 TABLE 2 Siliporite Siliporite NK30 NK30 AP AP Powder Adsorbent None Powder overexchanged Type of adsorbent 3A 3A Amount of 200 200 adsorbent (mg) TAN (mg KOH/g) 2.9 0.5 0.4

(12) It is thus observed that, in the presence of zeolitic adsorbent, the total acid number at the end of the test in the lubricant is greatly reduced, generally divided by 2 or 3. For the tests in the presence of HFO1234yf, it changes from 4.7 mg KOH/g without adsorbent to values of between 1.5 and 2.7 mg KOH/g with adsorbent. For the tests with R-134a, it changes from 2.9 mg KOH/g without adsorbent to 0.5 mg KOH/g with adsorbent.

(13) In addition, whatever the type of adsorbent (3, 4, 5 or 10 ), the results are identical: the total acid number is divided by a factor of approximately 2 in the tests carried out in the presence of 1 g of adsorbent.

EXAMPLE 2

Effect of the Zeolitic Adsorbent on the Reduction in the Water Content

(14) The test conditions are as follows: lubricant used: PAG ND8 lubricant weight of lubricant: 5 g weight of zeolitic adsorbent: 40 to 1000 mg ambient temperature duration: 2 hours

(15) The zeolitic adsorbent and the lubricant are introduced into a 10 ml colored flask. The flask is evenly stirred.

(16) After 2 hours, the adsorbent is allowed to separate by settling and the lubricant is analyzed: the water content is quantitatively determined by Karl Fischer coulometric titration, Mettler DL37. The results are presented in the following table 3:

(17) TABLE-US-00003 TABLE 3 Type of Amount of Adsorbent adsorbent adsorbent (mg) H.sub.2O (ppm) None 510 Siliporite NK30 3A 40 135 AP Powder Siliporite NK30 3A 200 70 AP Powder Siliporite NK30 3A 1000 30 AP Powder Siliporite NK30 3A 40 185 AP Powder overexchanged Siliporite NK30 3A 200 40 AP Powder overexchanged Siliporite NK30 3A 1000 30 AP Powder overexchanged Siliporite NK30 3A 1000 230 Beads (Static) Siliporite NK10 4A 1000 35 AP Powder Siliporite NK20 5A 1000 300 Siliporite G5 XP 10A 1000 520 Powder

(18) These results show that the zeolitic adsorbents of 3A and 4A type make possible better drying at ambient temperature than that obtained with adsorbents of 5A or 10A type.