claims: We claim: 1. In a p@ocess for producing lubricating oil having a high viscosity index and a low true color from a mineral oil containing naphthenic and paraffinic constituents, the steps comprisin.countercurrently contacting the oil with ari admixture of solvents comprising about 43% para40 chloropenol, 47% ortho-chlorophenol, and 10% phenol, cooling the mixture of oil and solvent until separation of an extract phase and raffinate phase occurs, separating said phases from each other, and distilling the soivent from said extract phase and raffinate phase. 2. In a process for producing lubricating oil having a high viscosity index and a low true color 5 from a mineral oil containing naphthenic and paraffinic constituents, the steps comprising commingling the mineral oil with an admixture of solvents comprising about 30 to 33% orthochlorophenol, 65 to 57% para-clilorophenol and 10 5 to 10% phenol, cooling the admixture of oil and solvents until separation of an extract phase and raffinate phase occurs, separating said phases from each other, and removing the solvent from each phase. 15 3. In a process for producing lubricating oil having a high viscosity index and a low true color from a mineral oil containing na-phthenic and paraffinic constituents, the steps comprising commingling the oil with a solvent comprising an 20 admixture of 25 to 39% ortho-chlorophenol, 70-45% para-chlorophenol and 5-16% phenol, cooling the admixture of oil and solvent to effect the formation of an extract phase and a raffinate phase, separating said phases from each other 25 and separating the admixture of solvents from each phase. 4. In a process for producing lubricating oil having a high viscosity index and a low true color from a mineral oil containing naphthenic and 30 parafflnic constituents, the steps comprising commingling the oil with a solvent comprising an admixture of 25 to 50% ortho-chlorophenol, 70 to 40% para-chlorophenol and 5 to 10% phenol, cooling the admixture of oil and solvent to a 311 temperature below 801 F. to effect the formation of an extract phase and a raffinate phase, separating said phases from each other and separating the admixture of solvents from each phase. 40 ARTHUR B. BROWN. FRED P. DIWOKY.

Patented Dec. 6, 1938 291389834 UNITED STATES PATENT OFFICE PP.OCESS OF TREATING OIELS Arthur B. Brown, Hammond, Ind., and Fred F. Diwoky, Chicago, M., assignors to Standard OR Company, Chicago, M., a corporation of Indiana Original application April 18, 1932, Serial No. 605,814. Divided and this applicatioii Blarch 26, 1935,, Serial No. 13,036 4 Claims. (CL 196-13) This invention relates to th6 extraction of mineral lubricating oils with organic solvents or mixtures of solvents for the purpose of preparing highly paraffinic oils with excellent color. 5 Petroleuni is essentially an admixture of hydrocarbons comprising severa'l groups or homologous series of compounds such as para:Mns, hydroaromatics, aromatics, polymethyl6nes, an(i various other series in which the hydrogen to carbon ratio 10 is even lower than in the above series. A large number of individual compounds of each series are present and have different boiling points, physical and chemical properties. In the various types of crude petroleum com15 moniy known as paraffmic base, naphthenic or asphalt base and mixed base, these various series of hydrocarbons are present in differentproportions. For example, in the paraffin base oils such as those from the Appalachian fleld, there 20 is a relatively high proportion of paraffinic hydrocarbons having a chain structure and a high hydrogen - to carbon ratio, whereas the Gulf Coastal oils have a high proportion of hydrocarbons with ring structures and a low hydrogen 25 to carbon ratio, which are generally referred to as non-paraffinic or naphthenic. The mixed base oils such as those fr6m Oklahoma and theMdContinent areas are in general intermediate these two extreme types. 30 :In the normal refining of crude petroleum, the fractions of varying distillation ranges which are successively obtained by distillation of the oils partake of the general character of the crude; for example, lubricating oils derived from Appa35 lachian crudes would show paraffinic characteristics; whereas the lubricating oils derived from Winkler Crude show naphthenic characteristics. The distillates from the mixed base crudes, such as those from the Mid-Continent area show 40 characteristics coinmon to both the parafflnic 'and naphthenic oils. Similarly, the undistfiled oils or residuums have properties similar to the crude from which they are prepared. An important property of paraffinic lubricating oils is 45 the low viscosity temperature coefficient or the rate of change of viscosity with temperature. This property makes them particularly suitable for certain lubricating problems *here high temperatures are encountered. At low temperatures 5o also, these oils retain their fluidity; this Is an important consideration in cold weather operation of automobiles. For this reason, it is very desirable to separate from the mixed base oils and other oils containing non-parafflnic constitu55 ents the undesirable non-paraffinic and naphthenic constituents. Var,.ous me@hods have been proposed for doing this. For example, the oil may be subjected to vigorous treatment with fumIng sulfuric acid, followed by neutralization and 6o removal of harmful sulfuric acid derivatives. An -object of this invention is to provide improved solvents for extracting the naphthenic constituents or non-paraffinic constituents from hydrocarbon lubricating oils so that the resulting oils will have improved viscosity temperature 5 charadteristics and wiR contain a high proportion of paraifinic hydrocarbons. These new solvents may be used for extracting lubricating oil distillates or residual lubrie'ating oils. j@ further object is to provide a method @for 10 treating petroleum oils contganing non-paraflinic cgnstituents without the expense and nuisance Gf acid treatment, and without the loss of valuable petroleum constituents which accompaiiies the use of acid treating. At the same time lubricat- 15 ing oils prepared by our process have a minimum tendency t , oward sludge formation when exposed to oxidizing conditions consistent with the Increased yield obtained. Also the solvent we eniploy removes more color from the oil than is 20 the case with most other solvents used to remove naphthenic constituents. A particular object of this invention pertains to the use of monochloro phenols and particularly ortho- and para-chlorophenol or mixtures of 25 these two. clilorophenois for extracting naphthenic or non-paraffaiie constituents from mineral oil. These solvents may be employed at ordinary temperatures, giving good phase separation without necessity of resorting to refrigeration. 50 The expression "viscosity lr@dex" as used hereIn refers specifleally to the index deflned by Dean and Davis in Chemical ' and Metallurgical Fngineering, vol. 36 (1929) page 618. The viscosity Index of a lubricating oil is an Indication of its 35 composition or type; 1. e., whether it is a paraffin base or naphthenic base oil. Parafdn base oils are arbitrarily assigned a viscosity index of 100, naphthenic base oils are assigned a viscosity index of 0 and rnixed base oils I lie between these do extr6mes. In accbrdance with one feature of the inv6ntion we have discovered that ortho-, meta-, and para-monochlorophenols or admixtures of monochlorophenolsl- for example, an admixture of 45 ortho- and para-chlorgphenol have remarkable solvent properties when used to extract the nonparaffmic or sludge formlng constituents from mineral oils. The commercial grades of these chlorodhenols may also be used, for example, the 50 product obtained by chlorination of phenol or by the partial hydrolysis of dichlorobenzenes by known methods. The proportions of the orthoand para-chlorophenols In the admixtures may vary over a wide range but generally from 25 to 55 50% of ortho-chlorophenol and 70 to 40% of para-chlorophenol is used. Also as much as 15% of phenol rnay be present in combingtion with the admixture of ortho- and para-chlorophenols, for example, a solvent comprising about 30 to 33% (10

2 2,138,834 ortho-chlorophenol, about 65 to 57% parachlorophenol and about 5 to 10@lo phenol may be used. These monochlorophenols and admixtures of monochlorophenols have the remarkable property of removing the color bodies from mineral oils. Without limiting the foregoing description of the solvents which may be used, the following examples of combined solvents may be employed: 10 Per cent Para-chlorophenol ---------------------- 43 Ortho-chlorophenol --------------------- 47 and Phenol --------------------------------- 10 15 Para-chlorophenol ---------------------- 50 and Ortho-chlorophenol --------------------- 50 Ortho-chlorophenol --------------------- 31 20 Para-chlorophenol ---------------------- 53 and Phenol -------------------------- ------ 16 Ortho-chlorophenol ------------------ --- 33 and 25 Para-chloro-phenol ------------------ -- 7-- 67 In our copending application 605,814, filed April 18, 1932, of which the present application is a division, we have described a process whereby 30 solvents such as the aliphatic ketones may be used in combination with the monochlorophenols. Examples of these ketones are acetone, methyl ethyl ketone, dietliyl ketone, di-isopropyl ketone, methyl butyi ketone, and mixtures of the above 35 ketones. Briefly, the invention is performed by mixing the mineral oil and chlorophenols at a temperature where substantially complete miscibility is obtained and cooling the mixture until phase 40 separation occurs. The temperature at which miscibility is obtained is termed "miscibility temperature" and the temperature at which phase separation is effected is termed the "extraction tem'perature". It should be understood that the 45 oil and chlorophenols may be mixed and thcn heated to any desired temperature, or the oil and chlarophenol may be -mixed at room temperatures and then permitted to separate into a raffinate and extract phase. The monochloro50 phenols and particularly the admixture of orthoand para-chlorophenols have the highly desirable property of effecting good phase separation at temperatures ra4ging from 30 to 801 F. This eliminates artiflcial cooling. The upper layer r,5 consists mainly of the paraffinic hydrocarbons and a small amount of solvent and is referred to as the "raffinate phase". The highly paraffinic oil is referred to as the raffinate. The major part of the solvent and the diss6lved non-paraf60 finic or sludge forming constituents separate in the lower phase and are referred to as the extract phase. The non-paraffinic oil is referred to as the extract. The respective liquid phases may be separated from each other by decanta66 tion or other suitable means. The raffinate consists of hydrocarbons which exhibit a high viscosity index and it is particularly suitable for lubricating oils. If desired, the raffinate may be given a further light refining treatment with clay, 70 sulfuric acid, or 9,lkali. The solvent is ordinarily recovered from the extract and raffinate by distillation and reused. It is also possil)le to extract the riaphthenic, non-paraffinic and/or sludge forming constitu75 ents from- mineral oils with these mono-chlorphenols when used in the presence of a nonviscous, normally gaseous liquid hydrocarbon such as propane, ethane, butane, pentane and the like. The term "propane,, is meant to include the light petroleum fraction which is gaseous 5 under normal conditions of temperature and pressure, and which is liquid at temperatures below 70' F. and 125 lbs. pressure per sq. in. Propane may be obtained from the cracking of hydrocarbon oils, rectification of natural gasoline 10 and the like, and it usually contains a small quantity of hydrocarbon such as methane, ethane, isobutane and butane. The purer grade of Propane may also be used. These non-viscous, normally gaseous liquid hydrocarbons are some- 15 times referred to as diluents. When mineral oils are extracted with an admixture of propane @,tnd monochlorophenol, the refined oil or raffinate is characterized by having a high viscosity index, a very light color, and a low Conradson carbon 20 value. Diluents such as light petroleum naphthas may also be used in the place of propane. The non-viscous, normally gaseous liquid hydrocarbons aid in bringing about a sharp phase separation. They may also be used as a refrigerant 25 to cool the mixture of oil and solvent by releasing pressure and permitting the liquefied gas to. expand directly from the mixture. However, it is seldom necessary to use artifleial cooling with the monochlorophenols because o:r their 30 abiiity to effect phase separation at ordinary temperatures. This invention is particularly applicabie to the treatment of any mixed base oil, Pennsylvania oil or residual oil; for example, it may be used 35 to remove the naphthenic or non-paraffinic constituents from oils having a Saybolt viscosity within the range of 200 to 3500 seconds at 100' P. The diluents may be used to reduce the viscosity of an oil to any point within this range of vis- 40 cosity. As an example of the method of carrying out one:embodiment of this invention, one volume of dewaxed mixed base lubricating oil distillate having a gravity of about 21.6 A. P. I,, viscosity 45 of 114 sec. Saybolt at @10' F. and a Dean and Davis viscosity index of 56.5 was extracted with two volumes of para-chlorophenol. The oil and solvent were heated to a miscibility temperature of 180' P. and cooled to an extraction tempera- 50 ture of 73' F. where.phase separation occurred. It should be noted that the extraction temperature used was equivalent to about normal room temperature. The following table shows the properties of the raffinate produced by the ex- r,5 traction with para-chlorophenol: Example I Raffinate Ratio of Mise Etrac- 60 Solvent soil to temp'. tion olvent y Vis. temp. leld izide Perce7it -F. -F. Parachlorophenol. 1:2 65 91.3 180 73 65 I From the above data it is apparent that parachlorophenol is very effective as a solvent for extracting the non-parafflnic constituents from a rnineral oil. It should be noted that by this one 70 extraction we were able to prepare an oil having a viscosity index of 91.3 and that It was not necessary to use artificial refrigeration to bring about phase separation. - The mono-chiorophenols are particularly useful as selebtive sol75

vents because th6y effect phase separation at relatively high temperatures. The raffinate described above also. had a very low true color. Another embodiment of this invention relates to the use of admixtures of these mono chlorophenols such as ortho- and parachlorophenol. In this particular example we used an adnlixtur'e comprising about one-third ortho-chlorophenol and two-thirds para-chlorophenol. ' The oil used 10 in this extraction was a dewaxed, mixed base lubricating oil distillate having a gravity of 21.6 A. P. I., true color of about 1100, a viscosity of 114 sec. Saybolt at 210' P. and a viscosity index of 56.5. One volume of this oil was extracted 15 three times with an equal volurae of the adrnixture of mono chlorophenols. The following t,,@ble shows the conditions under which the oil was extracted and the properties of the rafftnate. 20 Example II Raffinate Ratio of No. of Extrac@4o]vent oil to extrac- tibn temsolvent tions porature True Vigeosity 25 color index i%li-ture of about oqe-third orthochlorophonol and about twothirds para-chlo- -F. 30 rophonol 1:1 3 32-35 49 96 Sanie ------------- 1:1 3 72-80 3C) 96.5 From the above data it will be noted that the rafflnate had a very high viscosity index and a 35 very low true color. Phase separation can be obtained witb the chlorophenols at room temperatures without artificial cooling. The yield of raffinate in each of the above two extractions was between 40 and 50%. It is apparent that 491 the mono chlorophenols have the unique property of greatly improving the color of the oil. The diagrammatic drawing referred to hereinafter illustrates one type of apparatus which inay be used in the process of extracting mineral 45 oils with the novel solvents described hereinbefore. In this illustration of our invention, a continuous countercurrent extraction will be described; however, it should be understood that other methods of ptocedure may be used, such50 as batch extraction. The oil to be extracted is passed from the tank IO by the pump I I through conduit 12 to about the central part of an elongated vertical extraciion tower 13. A perforated pipe 14 Is usually. r)5 employed to introduce the oil into the tower. After the extraction tower has been substantially filled with the oil to be treated, a solvent such as an admixture of about one-third orthochlorophenol and two-thirds para-chlorophenol 00 is passed from the tank 15 by pump 16 through conduit 17 to the upper part of the extraction tower 13. A perforated pipe 18 is generally used to spray the solvent into the tower. The volumetric ratio of solvent to oil entering the tower 65 13 may vary frgm about one to four. 'rne same general ratio of oil to solvent may be usedwhen a single solvent like ortho- or para-chlorophenol is employed. The mono-chloropheziol, being heavier than 70 the oil, descends through the tower 13 a;nd effects a countercurrent extraction of the ascending body of oil. If clesired, a closed steam ebil 19 may be placed in the exttaction tower between the pipes 14 and 18, but nearer pipe 18, for the 15 purpose of heating the oil and solvent in that 3 region and thereby effecting greater miscibility of the oU and solvent. Flor example, the oil and solvent passing the coil 19 may be heated to a temperature of about 60 to 80' P. IAkewise, a siniilar closed coil 20 may be placed in the 5 lower part of the extraction tow . er for the circula,- tion of a cooling niedium to lower the temperature of the extract, e. g. to 30' F., and thereby bring about tl@e separation of any paraffinic oil wh,:ch may be otherwise carried out with the ex- 10 tract. The raffinate fraction is removed from the top part of the tower through conduit-21 and pass6d to the steam still 22 where the chlorophenols are distilled from the highly paraffinic oils or raffl- 15 nate. Steam is introdueed into the bottom part of the still 22 through the perforated pipe 23. If desired, external heat inay also be used to supplement the distillation of the chlorophenols from the oil. The paraffinic oils or rafrmate, freed 20 from the dissolved and entrained solvent, are removed from the bottom of ttie still through con'duit 24 located at the end of the still away from the inlet pipe 2 1. Baffles 25 may be placed in the still for the purpose of effecting a u'niform 26 flow of liquid througli the still and thereby insuring the removal of the chlorophenols from the oil before said oil or rafftnate is removed through pipe 24. The vaporized chlorophenois and steam re- 30 moved from the raffinate iraction in still 22 pass through conduit 25a to the cooling coils 26 where both are condensed. The liquefied chlorophenols an-d water pass to the separator 27 where the two liquids are permitted $5. to separate. The water being lighter than the chlorophenols ri8es to the top part of the separator and passes off through conduit 28. ' Gases and- uncondensed materials may be vented through the valved conduit 29. The condensed 410 chlorophenols are remgved from the bottom of the separator 27 through conduit 30 and returned to the solvent storage tank 15. The solvent and dissolved naphthenic constituents or extract fraction in the lower part of 45 the tower 13 are passed through conduit 31 and introduced into the steam still -32 'where the chlorophenols are distilled from the napbthenic constituents or extract without decomposition. Most of the chlorophenols which wer'e used In jSo the ext-raction of the oil will be found in the extrac t phase. Steaxn is introduced into the stih 32 through the perforated pipp 33. If desired, extern al iieat may be used to supplement the distillatio n of the chlorophenols from the naph- 55 theriie constituents. The naphthenic fraction of oil, freed of the solvent, is removed from the botto m of the still 32 through conduit 34, located at the end of the still -away from the inlet pipe 3 1. Baffles 35 are placed in the still for the 60 purpos e of causing a uniform flow of liquid throug h the still and thereby insuring the removal of practically all of the <-hlorophenols from the napht henic oil or extract before said oil is remove d through conduit 34. 65 The vaporized chloropenhols and water remove d from the naphthenic constituents in still 32 are passed through conduit 36 to the cooling coils 37 where both are condensed. The water and hquid chlorophenols pass to the separator 70 38 where the two liquids %re permitted to separate. The water being lighter than the chlorophenols rises to the top part of the separator and passes off throuo,,h conduit 39. Gases and uncondensed materials may be vented through 76

4 the valved conduit 40. The chlorophenols are removed from the bottom part of the separator 38 through conduit 41 and returned to the solvent tank 15. The method of extracting just described may likewise be employed with any of the solvents herein described. The paraffinic oils prepared by the use of these mo no-chlorophenols have a high v.iscosity Index, low true color, and are very resistant 'to sludge 10 formation. If desired, these parafflnic oils may be given a very light sulfuric acid treatment or clay treatment. In view of the extremely low color and very high paraffinic characteristics of the oils prepared by the chlorophenol extractiori, 15 said oils may be used for purposes other than that of lubricating internal combustion engines. As another modification of our process, the oils may ,be acidified with dilute sulfuric acid or other mineral acids before they are introduced int(> the ex20 traction tower 13. The presence of a small amount of acid tends to prevent the formation of emulsions. When an acidifled oil is used, the @affinate should be neutralized with caustic or some alkaline reagent before it is employed for lubricating purposes. This application is a division of our -copending application Serial No. 605,814, filed April 18, 1932. While we have described our invention with reference to specific operating conditions, it should be understood that our invention is not limited thereby. The particular features of our invention are set forth by the following