US2135922A

US2135922A - Method of refining mineral oils by means of inorganic fluorine compounds

Info

Publication number: US2135922A
Application number: US170975A
Authority: US
Inventors: Terres Ernst; Moos Josef; Ramser Hans
Original assignee: Edeleanu GmbH
Current assignee: Edeleanu GmbH
Priority date: 1937-10-25
Filing date: 1937-10-25
Publication date: 1938-11-08
Anticipated expiration: 1955-11-08

Description

Patented Nov. 8, 1938 UNITED STATES PATENT OFFICE METHOD OF REFINING MINERAL OILS BY MEANS OF INORGANIC FLUORINE COM- POUNDS No Drawing. Application October 25, 1937,

Serial No. 170,975

15 Claims. Our invention relates to the refining of mineral oil by means .of liquid or liquefied inorganic finer-- ine compounds, containing sulfur, which we have discovered to be particularly advantageous for B purifying mineral ofls of different boiling ranges and types.

More specifically our invention relates to the extraction of mineral oils by means of sulfur containing inorganic fluorine compounds as selective l solvents, for the purpose of dissolving the aromatic and unsaturated components of the oil and.thereby separating them from the parafiinic type.

Our invention further contemplates the separation of solid parafiine hydrocarbons, or wax, from those which are liquid at low temperature, by the use of liquid or liquefied inorganic sulfur containing fluorine compounds in admixture with auxiliary solvents which are miscible in any proportion with both, the oil to be refined and the selective solvents.

It is well known'in the art that, for example, naphtha fractions are composed of groups of components which are respectively designated as aromatic, unsaturated, hydroaromatic or naphthenic, and paramnic.

The hydroaromatic and parafiinic constituents of naphtha fractions are sometimes used as solvents in the cleaning industry, and they are of comparatively small value as compared with the olefinic and especially the aromatic constituents. These latter two groups of components are widely used as blending agents of gasolines for the purpose of increasing the octane number 5 of motor fuels and also as lacquer solvents and thinners. It is, therefore, important to provide for a process which will emciently separate the desirable oil constituents from the undesirable ones, for instance by extraction with selective 40 solvents which will dissolve the aromatic and burning 011. Here again it is necessary to separate the saturated from the unsaturated hydrocarbon groups in order to be able to use the respective oil. constituents for that purpose for which they are most suited.

Likewise in the field of lubricating oils it is generally recognized that hydrocarbon groups of low viscosity index and high carbon forming properties tend to decrease the stability. of the lubricating oil and that their removal will yield a refined oil of greatly improved characteristics, indicated especially by great resistance to oxidation, by a low carbon residue, and by a high viscosity index.

We have now found that sulfuricoxyfluoride, SO2F2, and sulfurhexafluoride, SFs, are particularly advantageous for separating the aromatic and olefinic type of oil components from the paraffinic type of constituents of oil fractions similar to those described above, because these solvents exert a very high degree of selectivity. To the same group of sulfur containing inorganic fluorine compounds which are suitable for oil refining in accordance with our invention belong also disulfur-difluoride, sulfur-difluoride and sulfur-tetrafluoride. Whereas at least some of the corresponding chlorine derivatives are known to be unstable in presence of mineral oil and react with it chemically, we have found that the above cited sulfur containing inorganic fluorine compounds do not decompose and do not form sludge or react otherwise chemically with the hydrocarbon oil to be extracted.

The following examples will further illustrate our invention as so far disclosed:

Y Example 1 One volume of straight-run naphtha was agitated with one volume sulfuricoxyfiuoride and Example 2 A transformer oil was treated with 10 sulfuricoxyfluoride at +28 C. Two layers were obtained which were separated and from which the solvent could be recovered without decomposition of the oil or part thereof.

Example 3 A lubricating oil distillate of '75 viscosity at 210 F. and 28 A. P. I. gravity was agitated with an equal volume of sulfuricoxyfluoride at room temperature. A separation into two phases occurred.

Example 4 A dewaxed Mid-Continent overhead cylinder stock was treatedwith sulfurhexafluoride at 51 C. at a pressure of 570 pounds per square inch by gauge. Two layers were formed which were separated from each other, the rafiinate be,- ing the upper layer. No chem cal reaction bemiscible with the oil.

tween the solvent and rafllnate or extract occurred in this test nor in the other experiments shown.

Example 5 A Mid-Continent residual oil upon agitation with an equal volume of sulfuricoxyfluoride at 87 F. showed a separation into two layers.

In carrying out our extraction process one of the above mentioned inorganic fluorine derivatives may be usedeither alone or in mixture with one or more of the others.

Our invention is further not limited to the use of one or more of the selective inorganic fluorine compounds. In some instances, especially when extracting heavy lubricating oils, it is of advan tage to carry out the extraction in the presence of an auxiliary solvent for the purpose of facilitating the extraction and further controlling the extent thereof. Such auxiliary solvents may be selected from the class which is miscible in any proportion with both the selective solvent and the hydrocarbon oil to be treated, if the solvent power of the selective solvent is to be increased. Representatives of this class of auxiliary solvents are the aromatic hydrocarbons, the non-selective class and from to 50 volumes per cent selective inorganic" fluorine solvent.

We may also use our selective inorganic fluorine solvents in mixture with an auxiliary solvent of the class which is miscible in any proportion with the selective'solvent but substantially im- Representatives of this class are for example the alcohols and they serve to further increase the selectivity of our selective solvents.

In other instances the presence during the extraction step of substantial volumes of light petroleum fractions such as propane or butane or the presence of dichloro-difiuoro methane is .of advantage. l

It is further to beunderstoodthat, instead of the batch treating method described above, also,

the well known counter current operating method may be used, employing therefor either a tower packed with Raschig rings .or provided with plates, or a mixing and settling tank equipment consisting of three or more stages.

Qur selective inorganic fluorine solvents are also suitable for dewaxing when used inthe Presence of an auxiliary solvent of the class which is miscible in any proportion with both the oil to be dewaxed and the selective solvent, If such auxiliary solvent is added to a mixture of waxy oil and inorganic fluorine solvent the temperature of complete miscibility will be reduced, this reduction depending upon the amount of auxiliary solvent added. We found that in addbelow substantially all the liquid hydrocarbons but will exert substantially no solvent action on the solid hydrocarbons. When a wax oil is dissolved in such solvent blend at elevated temperature and the solution is thencooled to 09 1'. or below, the solid hydrocarbons will crystalline out and may be removed from the dewaxed oil solution by filtering, centrifuging or decanting.

' It'is further to be understood that the extraction step as described above may also be combined with the dewaxing in which case the extracted oil, before removal of solvent, is further diluted with a mixture of selective solvent and auxiliary solvent in the proportions disclosed above, cooled to 0 1''. or below and subjected to filtration. Likewise the extraction may follow the dewaxing in which case more selective solvent is added to the dewaxed oil solution until at least separation into two phases occurs.

Obviously modifications and variations of our invention as hereinabove set forth, may be made without departing from the spirit and scope thereof.

This application is a continuation in part of the application Serial No. 23,130 filed May 28, 1935 for Method of refining mineral oils." 4

We claim the following as our invention:

1. A method of refining a mineral oil comprising extracting the oil with a selective solvent pound containing sulfur, to produce a separation into relatively parafiinic and non-parafiinic'.

phases, separating the phases from each othcr and recovering the solvent therefrom.

2. A method of refining a mineral oil comprising mixing the oil with sulfuricowfluoride as selective solvent and adjusting the temperature to produce a separation into two oil-containing phases, and separating the phases.

3. A method of refining a mineral oil comprising mixing the oil with sulfurhexafiuoride as 'se-" lective solvent and adiusting the temperatureto produce a separation into two oil-containing phases, and separating the phases.

4. A method of refining s. mineral oil compris ing extracting the oil with a selective solvent con sisting of a liquefied inorganic fluorine compound containing sulfur, in admixture with an aux-" iliary solvent to produce a separation-into two relatively paraiiinic and non-paramnic phases, separating the phases from each other and recov-f-- ering the solvents therefrom.

5. A'method oi'refining a mineral oil compelsing extracting the oil with a selective solvent consisting of a liquefied inorganic fluorine compound containing in admixture with an auxilia'ry solvent of the class which is miscible in any Proportion with both the oil andthe select? solvent to produce a separation into two rell'- I tively paraflinic and non-parafiinic phases, separating the phases fronr each other and recovering the solvents therefrom.

6.'A method of refining a mineral oil comprising extracting the oilwith a selective solvent consisting of a liquefied inorganic fluorine compound containing sulfur, in admixture with an auxiliary solvent of the class which is miscible with at least one of the components of the mixture of selec-- tive solvent and oil to be extracted to produce a separation into two relatively parafiinic and V non-parafiinic phases, separating the, phases from each other and recovering the solvents therefrom.

'I.A method of refining s mineral oil comprising extracting the oil with liquefi d sulfuricoxyfiuoride as selective solvent in admixture with an auxiliary solvent to produce a separation into two relatively parafiinic and non-parafllnic phases, separating'the phases from each other and recovering the solvents therefrom.

8. A method 0:: refining a mineral oil comprising extracting the oil with liquefied sulfurhexafluoride as selective solvent in admixture with an auxiliary solvent to produce a separation into two phases, separating the phases from each other and recovering the solvents therefrom.

9. A method of dewaxing a mineral oil comprising dissolving the oil in a mixture containing as a selective solvent, a liquefied inorganic fluorine compound containing sulfur, and an auxiliary solvent of the class which is miscible in any proportion with both the oil and the selective solvent and in such proportion as not .to produce a separation into two liquid layers at the dewaxing temperature, cooling the mixture to below the desired pounpoint, removing the wax therefrom and recovering the solvents from the dewaxed oil solution and from the wax.

10. A method according to claim 9 in which the selective solvent is sulfuricoxyfiuoride.

11. A method according to claim 9 in which the selective solvent is sulfurhexafluoride.

12. A method according to claim 9 in which the selective solvent is sulfuricoxyfiuoride and the auxiliary solvent is a substance of the class of benzol and its homologues.

13. A method according to claim 9 in which the selective solvent is sulfurhexafiuoride, and the auxiliary solvent is a substance of the class of benzol and its homologues.

14. A method of producing lubricating oils of high viscosity index and low pour point comprising extracting the oil in accordance with the method of claim 1, adding to the raflinate phase so obtained before recovery of solvent therefrom, further amounts of the selective solvent and an auxiliary solvent of the class which is miscible in any proportion with the oil and the selective solvent in such proportion as not to produce a separation into two liquid layers at the dewaxing temperature, cooling the mixture to below the desired pour point and removing the wax therefrom.

15. A method of producing lubricating oils of high viscosity index and low pour point comprising dewaxing the oil in accordance with the method of claim 9, adding to the dewaxed oil mixture so obtained, before recovery of solvent therefrom, a further amount of selective solvent to produce a separation into phases relatively paraflinic and non-paraflinic and separating the phases from each other.

ERNST TERRES. JOSEF MQOS. HANS RAMSEB.