US2143890A

US2143890A - Process of refining petroleum oils

Info

Publication number: US2143890A
Application number: US746516A
Authority: US
Inventors: Liberthson Leo
Original assignee: SONNEBORN SONS Inc L
Current assignee: L SONNEBORN SONS Inc; SONNEBORN SONS Inc L
Priority date: 1934-10-02
Filing date: 1934-10-02
Publication date: 1939-01-17
Anticipated expiration: 1956-01-17

Description

Patented Jan. 17, 1939 PROCESS OF REFINING PETROLEUM OILS Leo Liberthson, New York, N. Y., assignor to L.

Sonneborn Sons, Inc., a corporation of Delaware No Drawing. Application October 2, 1934, Serial No. 746,516

10 Claims.

The object of the invention is to provide an improved method of refining petroleum oils and more especially, an improved method of preparing a white medicinal oil.

5 In accordance with prior practice, white mineral oils are prepared by subjecting a carefully selected fraction of a crude petroleum to treatment with large quantities of acid, usually fuming sulphuric acid, the quantity of acid required for 10 the preparation of the most highly refined medicinal oils being of the order of 75% or more by volume of the oil treated. By such processes the yield of final product in general does not exceed 50% of the amount of the fraction used in its 15 preparation, the remaining 50% comprising acid sludge which is of relatively little value. Furthermore the product or products obtained have less desirable physical characteristics than do products obtained in accordance with this inven- 2 tion.

White mineral oils such as those used for medicinal purposes are substantially water-white viscous products which, in accordance with the prior practice, have been obtained by subjecting 25 a carefuly selected fraction of a crude petroleum, as for example, a fraction from a napthenic crude, to a drastic acid treatment as aforesaid. This treatment, due to the large quantities of strong acid used, results in the destruction of the less 30 stable constituents contained in the oil, which probably accounts for the high oil loss incident to such treatment. This loss is referred to as an oil loss since the portion of the oil which reacts with the acid to form a sludge is only 35 partially recoverable, and even when recovered it is usable only as a low grade fuel oil which has a very low market value.

Furthermore, processes in accordance with the prior practice whereby white mineral oils are 40 produced, require the use of oils of relatively low viscosity due to the fact that if treatment of the heavier oils is attempted, much difliculty is encountered and in addition high chemical and mechanical losses result.

45 I have discovered that a pure white medicinal oil may be obtained by treating a viscous mineral oil such as a petroleum lubricating oil distillate,

with dichloroethyl ether to remove major components of the oil which react with sulphuric acid.

50 The oil, which still contains small amounts of reactable components, is then treated with sulphuric acid, and preferably with oleum, forming an acid sludge. The acid sludge is separated from the oil and the oil is further treated with di- 55 chloroethyl ether. The dichloroethyl ether extract is separated from the oil and the oil is then treated with a stripping solvent such as an alcohol, acetone, etc. The extract is separated from the oil and an inert gas such as air, nitrogen, etc., is passed through the oil to remove re- 5 maining small amounts of stripping solvent and dichloroethyl ether. If desired, the oil may be given a slight alkali treatment to neutralize such minute traces of acid as may have survived the previous extractions. The oil may then be 111- tered to remove traces of dichloroethyl ether and a pure white medicinal oil is obtained.

This product is superior to medicinal oils heretofore obtained, and the yield is appreciably higher. Furthermore, as indicated above, only a small amount of sulphuric acid or oleum is necessary in the treatment, because the major amount of naphthenic and unsaturated components of the original oil, which are reactable with sulphuric acid are removed by the first dichloroethyl ether treatment.

The invention may be carried out by subjecting one volume of viscous mineral oil, such as a Pennsylvania petroleum lubricating oil distillate, preferably by countercurrent extraction, to the action of two volumes of dichloroethyl ether to separate the components reactable and nonreactable with sulphuric acid. The dichloroethyl ether extract dissolves out the naphthenic and unsaturated components which react with sulphuric acid, and the raiiinate comprises principally the mineral oil containing the parafllnic hydrocarbons. The lower dichloroethyl ether extract layer is separated from the upper oil rafflnate layer, and if desired, the oil may be further treated with dichloroethyl ether. Preferably, the original oil is extracted three times by countercurrent extraction with dichloroethyl ether, but I am not to be limited to any number of extractions.

The oil now contains about 10% of dichloroethyl ether in solution, and is treated with 20 to 30% of sulphuric acid, and preferably oleum. It is not necessary to remove the dichloroethyl ether remaining in solution and in fact, I regard its presence as highly desirable inasmuch as it facilitates the action of oleum on the oil by removing the sulfonic acids as areaction phase as fast as formed, thus permitting the reaction to arrive at a greater degree of completion than if it were absent. The concentration of SO: in the oleum may range over considerable limits, although 20% oleum, viz., acid containing this percentage of S03 is satisfactory. The temperature of application of the acid is regulated in the manner well known in the art, to produce the desired sulfonation reaction, and, in general, temperatures not exceeding 140 F. are preferred.

If desired, the original mineral oil need not be given a preliminary treatment with dichloroethyl ether, but such ether may be added to the oil up to its solubility limit, and the oil may then be treated with oleum. In this case, a larger amount of oleum will be required, but the sulfonation reaction will arrive at a greater degree of completion than if no dichloroethyl ether were present.

The organic acids in the sludge may compose from 25 to 75% of the total sludge, and while slightly soluble, if at all, in hydrocarbon oils, are highly water soluble. The free acids in aqueous solution are dark green in color and for this reason are generally referred to as "green petroleum sulfonic acids. The acids left in solution in the oil impart a reddish color to the oil containing the same and for this reason are generally referred to as mahogany petroleum sulfonic acids. The oil may also carry variable amounts of the green petroleum sulfonic acids as finely dispersed or mechanically suspended particles. The mahogany acids are soluble in dichloroethyl ether and may be efficiently and easily removed by admixing dichloroethyl ether with the oil.

In the ordinary method of removal, these acids are first converted into salts by neutralization, but in my process this neutralization is not necessary and the free acids are extracted as such. For while neutralization yields salts of both green and mahogany acids in a mixture which is separable only with great difiiculty, direct extraction with dichloroethyl ether permits the quantitative separation of these types of acids by virtue of the fact that dichloroethyl ether precipitates the green and dissolves the mahogany acids. This should be done after the oil has been separated from the sludge formed on reaction with sulphuric acid. The dichloroethyl ether is soluble in the oil to the extent of several percent and it is therefore necessary to add the dichloroethyl ether in an amount which exceeds its solubility in the oil, thereby yielding a two layer system. The dichloroethyl ether forms a lower layer ranging from 5 to 25% by volume of the oil from which it separates. In any case, it should not be necessary to use more than 50% by volume of dichloroethyl ether to produce a second liquid phase in order to obtain the complete removal of the sulfonic acids, and sharp separation into two layers. These limits are merely intended as illustrations and not in any way as restrictions on the scope of the invention. The residual green sulfonic acids dissolved in the oil as stated above are not soluble in the dichloroethyl ether but are coagulated by contact with it and are precipitated as completely discreet and easily removable sludge, which forms an intermediate layer between the oil and dichloroethyl ether layers. The oil soluble sulfonic acids, on the other hand, will be found to have passed almost exclusively into the lower dichloroethyl ether layer, and to have been almost completely removed from the oil. The lower layer is separated from the oil and may, if desired, be treated to recover the mahogany acids in usable form. If desired, extraction with dichloroethyl ether may be carried out countercurrently a number of times, and I have found that about three extractions precipitate substantially all of the green acids and extract substantially all the mahogany sulfonic acids from the oil.

The oil layer is then treated with a stripping solvent, which may be an alcohol having not more than three carbon atoms, or other solvent having a high vapor pressure and a boiling point of preferably not greater than 80 C. The solvent should be miscible with the dichloroethyl ether but substantially immiscible with the oil, so that two well defined layers will be formed. As examples of such stripping solvent may be mentioned methyl alcohol, ethyl alcohol, propyl alcohol, acetone, methyl ethyl ketone, etc. The stripping solvent removes the dichloroethyl ether and any mahogany acids and other impurities which may be left in the oil layer. The stripping solvent extraction, if desired, may be carried out a number of times, as for example, by countercurrent extraction three times. In each case, the stripping solvent extract is separated from the oil before the next extraction.

After the last separation, the oil contains small amounts of stripping solvent and dichloroethyl ether, and these may be removed by passing an inert yas through the oil. The inert gas, such as air, nitrogen, etc., may be at ordinary temperatures or elevated temperatures. The inert gas removes all of the alcohol and substantially all of the dichloroethyl ether and traces of the latter can be removed by treatment with an adsorbent material, for example, with adsorbent clay, etc. The clay treatment may be carried out in any suitable manner, as for example, by running the oil through a porous bed of fullers earth, or the like, in a percolation type of filter, or, by admixing the oil with fine adsorbent clay, and thereafter settling or filtering the same.

The pure, white medicinal 011 formed has a Saybolt viscosity at 210 F. of 390-400 and the yield is about 75%, as compared with a viscosity of 335-350 and yields of about 50% with processes heretofore used. It is superior to that ordinarily produced from a corresponding raw material with the amount of oleum necessary to convert it to a white medicinal oil, and in particular will be markedly superior in its resist ance to the effect of prolonged exposure to light and/or to ultra violet light. There are no minute traces of oil soluble organic material in the oil, and these is substantially no objectionable odor, color, or taste upon exposure to natural or ultra violet light for prolonged periods.

I am not to be limited to any number of extractions with dichloroethyl ether or stripping solvent, nor to any volume of extracting substances. By stripping solvent as used in the specification and claims I mean an alcohol having not more than three carbon atoms, or other solvent miscible with dichloroethyl ether and substantially immiscible with oil, and having a sufficiently high vapor pressure and low boiling point to permit removal by passing an inert gas through the oil.

I claim:

1. In the art of refining mineral oils, the step comprising ,treating a viscous mineral oil with fuming sulphuric acid under sulphonating conditions of acid quantity and temperature in the presence of dichloroethyl ether in amount sulfi- .cient to thereby form simultaneously a first layer containing predominantly dichlorethyl ether and dissolved mahogany sulphonic acids, and a coagulated precipitate containing predominantly green sulphonic acids.

2. In the art refining mineral oils, the steps which comprise extracting a viscous mineral oil with dichloroethyl ether to dissolve from the oil a substantial part oi the components thereof which react with sulphuric acid, separatingthe dichloroethyl ether from that portion of the oil which remains undissolved therein, and treating the undissolved portion of the oil with sulphuric acid under sulphonating conditions of acid quantity and temperature in the presence of the dichloroethyl ether soluble in the oil to thereby form simultaneously a layer substantially free from mahogany and green sulphonic acids formed by the acid treatment and containing predominantly mineral oil and dissolved dichloroethyl ether, and an acid sludge containing mahogany and green sulphonic acids.

3. In the art 01 refining mineral oils, the steps which comprise repeatedly extracting a viscous mineral oil distillate with dichloroethyl ether to dissolve from the oil a substantial part of the components thereof which react with sulphuric acid and separating the dichloroethyl ether layers from that portion of the oil which remains undissolved therein, and treating the undissolved portions of oil with oleum under sulphonating conditions of acid quantity and temperature in the presence of the dichloroethyl ether soluble in the oil to thereby form simultaneously a layer substantially free from mahogany and green sulphonic acids formed by the acid treatment and containing predominantly mineral oil and dissolved dichloroethyl ether, and an acid sludge containing mahogany and green sulphonic acids.

4. In the art of refining mineral oils, the process comprising extracting a viscous mineral oil with dichloroethyl ether to dissolve from the oil a substantial part of the components thereof which react with sulphuric acid and removing the dichloroethyl ether layer, treating the oil layer with sulphuric acid under sulphonating condi-- tions of acid quantity and temperature in the presence of the dichloroethyl ether soluble in the oil to thereby form simultaneously a layer substantially free from mahogany and green sulphonic acids formed by the acid treatment and containing predominantly mineral oil and dissolved dichloroethyl ether, and an acid sludge containing mahogany and green sulphonic acids, separating said acid sludge from said oil layer, extracting said oil layer with dichloroethyl ether and removing the dichloroethyl ether layer, treating the oil layer with a stripping solvent, removing the solvent layer, and passing an inert gas through the oil layer so as to remove thereby stripping solvent and dichloroethyl ether dissolved in the oil.

5. In the art of refining mineral oils, the process comprising repeatedly extracting a viscous mineral oil distillate with dichloroethyl ether to dissolve from the oil a substantial part of the components thereof which react with sulphuric acid and removing the dichloroethyl ether layers, treating the oil layer with oleum under sulphonating conditions of acid quantity and temperature in the presence of the dichloroethyl ether soluble in the oil to thereby form a layer substantially free from mahogany and green sulphonic acids formed by the acid treatment and containing predominantly mineral oil and dissolved dichloroethyl ether, and an acid sludge containing mahogany and green sulphonic acids, separating said acid sludge from said 011 layer, repeatedly extracting said oil layer with dichloroethyl ether and removing the dichloroethyl ether layers, treating the oil layer with a stripping solvent, removing the solvent layer and passing an inert gas through the oil layer so as to remove thereby the stripping solvent and dichloroethyl ether dissolved in the oil.

6. Process in accordance with claim 5 in which said stripping solvent is alcohol and in which the inert gas passed through said oil layer is air.

7. Process in accordance with claim 5 in which said stripping solvent is acetone and in which said inert gas passed through said oil layer is a r.

8. In the art of refining mineral oils, the proccess comprising repeatedly extracting a viscous 'mineral oil distillate with dichloroethyl ether to dissolve from the oil asubstantial part or the components thereof which react with sulphuric acid and removing the dichloroethyl ether layers, treating the oil layer with oleum under sulphonating conditions of acid quantity and temperature in the presence of the dichloroethyl ether soluble in the oil to thereby form a layer substantially free from mahogany and green sulphonic acids formed by the acid treatment and containing predominantly mineral oil and dissolved dichloroethyl ether, and an acid sludge containing mahogany and green sulphonic acids, separating said acid sludge from said oil layer, repeatedly extracting said oil layer with dichloroethyl ether and removing the dichloroethyl ether layers, treating the oil layer with a stripping solvent, removing the solvent layer and passing an inert gas through the oil layer so as to remove thereby the stripping solvent and dichloroethyl ether dissolved in the oil, and treating said oil layer with an adsorbent agent.

9. In the art of refining mineral oils, the process which comprises extracting a viscous mineral oil distillate with dichloroethyl ether to dissolve from the oil a substantial part oi. the components thereof which react with sulphuric acid, removing the dichloroethyl ether layer, treating the oil layer with a further quantity of dichloroethyl ether to further dissolve from the 011" components thereof which react with sulphuric acid, again removing the dichloroethyl ether layer, treating the oil layer with oleum under sulphonating conditions of acid quantity and temperature in the presence of the dichloroethyl ether dissolved in the oil to thereby form simultaneously a layer substantially free from mahogany and green sulphonic acids formed by the acid treatment and containing predominantly mineral oil and dissolved dichloroethyl ether, and an acid sludge containing mahogany and green sulphonic acids, separating said acid sludge from said oil layer, treating the oil layer with dichloroethyl ether, separating the dichloroethyl ether layer, treating the acid treated oil with a further portion of dichloroethyl ether, again removing the dichloroethyl ether layer, treating the oil layer with a stripping solvent, removing the solvent layer, treating the oil layer with a further portion of stripping solvent, again re moving the solvent layer, and passing an inert gas through the oil layer so as to remove thereby the stripping solvent and dichloroethyl ether dissolved in the oil.

10. In the art of refining mineral oils, the proc: ess which comprises extracting a viscous mineral oil distillate with dichloroethyl ether to dissolve i'rom the oil a substantial part of the components thereof which react with sulphuric acid, removing the dichloroethyl ether layer, treating the oil layer with a further quantity of dichloroethyl ether to further dissolve from the 011 components thereof which react with sulphuric acid, again removing the dichloroethyl ether layer, treating the oil layer with oleum under sulphonating conditions of acid quantity and temperature in the presence of the dichloroethyl ether dissolved in the oil to thereby form simultaneously a layer substantially free from mahogany and green sulphonic acids formed by the acid ;treatment and containing predominantly mineral oil and dissolved dichloroethyl ether, and an acid sludge containing mahogany and green sulphonic acids, separating'said acid sludge from said oil layer, treating the oil layer with dichloroethyl ether, separating the dichloroethyl ether layer, treating the acid treated oil with a further portion of dichloroethyl ether, again removing the dichloroethyl ether layer, treating the oil layer with ethyl alcohol, removing the alcoholic layer, passing air through the oil layer so as to remove thereby alcohol and dichloroethyl ether dissolved in the oil, and treating said 011 layer with an adsorbent agent.

- LEO LIBERTHSON