US1912349A - Process for separation of mineral oil - Google Patents

Description

May 30, 1933. l M, H. TUTTLE 1,912,349

PROCESS Fon SEPARATION 0F MINERAL OIL Filed Dec. 22, .1932

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FRACHON B NAPmnemc INVENTOR MMM# M 2 ATTORNEYS Patented May 30, 1933 UNITED -STATES PATENT oF-FlcE MALCOLM H. TUTTI-IE, F NEW BUCHELLE, NEW YORK PROCESS FOB SEPARATION 0F MINERAL OIL I/ Application tiled December 22, 1838. Serial No. 648.883.

This invention relates to a recess for the separation of mineral oil into ractions which are `respectively more parainic 1n composition and characteristics and more n aphthenic in composition and, characteristics than-is the original oil and which ,may have 1 of being oils from the Appalachian lield; and

oils containing a relatively lower roportion of paraiiinic constituents and t erefore a relatively higher proportion o f naihthenic constituents are commonly calle naphthenic or Aasphaltic base oils, an example of such oils being oils obtained from Gulf Coastal or Mexican fields; and oils containing an intermediate proportion of paraiiinic' constituents and also containing naphthenic constituents are commonly called mixed base oils, an example of such oils being oils from the Mid-Continent fields. Paraiiinic oils having a given viscosity have a lower specific gravity, a higher ash test, a smaller change of viscosity with changes in temperature and a higher ratio of hydrocarbon to carbon than do naphthenic oils of the lsame viscosity. Parailinic oils are more suitable and more desirable as lubricants, particularly under conditions involving .high temperatures and im extensive changes of temperature, than are oils in which paraiiinic constituents are present in relatively lower proportion 'and naphthenic constituents are present in relatively high proportion. The characteristics of Mid-Continent or mixed base oils are intermediate the characterictics of parilin base and asphalt base oils.

Naphthenic oils are preferable to parafinic oils for some uses, such as insulating oils for electrical apparatus and lubrication of REISSUED chains and of gearing not subjected to low temperatures.

An object of this invention is to a recess whereby mineral oils may id y and economically separated into fractions which are respectively more parainic and more naphthenlc in composition and in characteristics than is the original oil, the separation being eifected regardless of whether the oil has previously been subjected to acid treatment or dewaxing treatment or both, and without chemical reaction and without formation of sludge, to the end that solvents employed to effect such separation may be used indefinitely and lossesV minises" mized. A specific object of this invention is to provi e a method whereby oils obtained from mixed base ipetroleum may be separated into fractions o which at least one is a lubricating oil stock having viscosity-gravity characteristics and viscosity-temperature characteristics similar to or equal to or better than such characteristics of oil stocks having 'similar viscosity and Vobtained by usual distillation from crude oils from the Penns lvania field, a further object being the prouction' from decidedly naphthenlc or asphaltic oil of an oil fraction of which the characteristics are at least substantially more parainic than the characteristics y of the ori 'nal oil.

o assist in understandin the e'ects and results of the practice of this mvention, reference may be made to certain values commonl employed to indicate the character of oil Thus the relation of viscosity to specific gravity is indicated by the viscosity-gravity constant determined `in accordance with the following equation:

a ('-0.240.22 log (V.35.5)

where a=viscositygravity constant V'=Saybolt viscosity at 210 F. G=specific gravity at F.

Continent lubricatin oils have a viscositygravity constant fa ing between approximately .827 and .867; and na hthenic or ashalt 4base lubricating oils rom the Gulf ast and California have a viscosity-gravit constant falling between approximately .86% and .S8-7. However, specific oils from one eld will have a viscosity-gravity constant falling within the range above iven for Aanother field. Moreover, the relation of temperature to viscosit is measured b a viscosity index in which ennsylvania oi s have a value of 90 to 100 and oils of lower viscosit are less paralnic and the oils of big er viscosit index are more paralinic.

It as heretofore been proposed to treat oil with sulphuric acid for the removal of ashalt and unstable unsaturated hydrocarns, but such treatment involves chemical A reaction and production of sludge from which the recovery of asphalt is diilicult and uneconomical, and loss of parailinic constituents carried down with the slud e; and the treated oil retains marked napht enic characterisg5 tics.

It has been proposed heretofore to divide mineral oil containing naphthenic and parafiinic-fractions into fractions more parailinic and more na hthenic than the original oil b an extracting t e oil with nitro-aromatic so vents, which may-be termed naphthenic solvents in that they have greater solvent power for naphthenic constituents than for parafinic constituents, the mixture separating by gravity into an upper layer comprising the more parainicl fraction and some ofthe solvent and a lower layer comprising the more naphthenic fraction dissolved in a majorl proportion of the solvent. ,Such treatment of mixed base oils having a high or intermediate asphalt content, and articularly such treatment of the residue o such oils, by the use of selective solvents heretofore roposedl has proven impractieable or has fai ed. The a parent cause is that the solvents proposed w en used in roportions determined b economical consi erations a ear to be m'iscible with residual oils of hig or intermedi-ate content of naphthenic constituents or asphalt,

with the resu t that the necessary separation into layers does not occur. It ap ears that the nitro-aromatic solvents form with the asphalt or with the liquid naphthenie constituents, or with both a mixture having extensive solvent power for parainic constituents. Cresylic acid has selective solubility for na hthenic constituents, but when used in su cient roportion to take a substantial proportion o naphthenic constituents into solution, in an eifort to divide oil into naphthenic and arailinic fractions -by extraction, it has a su antial solvent power for parainic constituents.

I have found that mineral oil containing c parainic and naphthenic constituents can be indexv separated into fractions respectively more paraliinic. and more naphthenic than the original oil by subjecting the'oil to contact with cresy'lic acid in the presence of a solvent which has greater solvent power for parafflnic constituents than for na hthenic constituents, the treatment prefera ly being applied under such conditions that the solvents employed are mutually miscible to only a limited extent. It ap ears that under such conditions, the norma selectivity of cresylic acid for naphthenic constituents is increased or its solvent power for arailnic constituents is decreased, particu arly when the solvent of parailnic constituents has limited solubility for and in the cresylic acid; and it appears also that the selectivity of the solvent for paraflnic constituents is increased or its solvent power for naphthenic constituents is decreased in the presence of cresylic acid. When the oil is contacted with cresylic acid in the presence of Asuch a parainic solvent, se arationoccurs prom tly and readily.

accordance with invention, therefore, mineral oils are se arated into fractions respectively 'more para ic and more naphthenic than the or l oil by extracting the oil with cresylic acid in an operation in which at least some art of the contacting of the oil with cresylic acid occurs in the presence of a solvent having greater solvent power for arailinic constituents. than for naphthemc constituents. In the presence' of such solvent, the tenden of the cresylic acid, when present in sufficient proportion to effect substantial extraction or solution of the naphthenic constituents, to ltake into solution` a substantial proportion of the 'paranic constituents, is minimized; `and there is produced from a mixed base or naphtlienic oil a fraction having characteristics similar to or equal to or better than the characteristi of a similar fraction obtained from paran base oil, or there is produced a fraction having characteristics at least markedly more parallinic than the orinal oil. Thus, the extraction of the oil wi cresylic acid in the presence of a paranic solvent produces results heretoforeV unobtainable by the use of cresylic acid alone.

Commercial cresylic acid comprises orthocresol, metacresol,paracresol, phenol and xylenol and a reference herein to cresylic acid is intended as a reference to such acid or to those components thereof or to mixtures of an two or more of those components. Such su ances can readily be removed from'the oil by distillation at temperatures which do not tend to decompose the oil or the s ubstances.

Paranic solvents suitable for use in the practice of this invention include ethane, propane, butane, pentane, natural soline and light naphtha, such light na ht a preierably being preliminarily treat with a sol- 131.

vent, such as cresylic acid, having a selective solvent ower for naphthenic constituents of oil. uch parailinic solvents have a limited solubility in and for cresylic acid and a greater solvent power for parainic constituents of oil than for cresylic acid and they may be removed from the cresylic acid and from the oil for re-use by distillation which does not involve the use of temperatures that would decompose the oil or the cresylic acid.

In the practice of this invention, the oil to be divided into fractions is, at least at one point in the treatment thereof, contacted sivmultaneously with cresylic acid and a paraffinic solvent and such contacting may be effected in a batch operation, or in a continuous operation in which there is preferably maintained a counter-flow of solvents while the oil is introducedv to such counter-flow at an intermediate point thereof and the nephthenic fraction is taken oil at a point on the same side of the oint of introduction of the oil as the point o introduction of the paraffinic solvent and the naphthenic fraction is taken ol at a point on the opposite side of the point of introduction of the oil.

The solution of naphthenic constituents is heavier than the solution of paraflinic constituents and in the separating operation the solution of paraiiinic constituents forms ultimately an upper layer and the solution of naphthenic constituents forms ultimately a lower layer. In continuous extraction, the se aration occurs in the counter-flow system. T e solution of the paraiiinic fraction will comprise paraiinic constituents and nephthenic constituents in a ratio substantially greater than the ratio of paraliinic constituents to naphthenic constituents in the original oil and it will contain the major portion of the parailinic solvent and some of the naphthenic solvent. The solution of naphthenie constituents will include naphthenic constituents and paranic constituents in a ratio greater than the ratio of naphthenic constituents to parainic constituents in the original oil and will contain the major ortion of the naphthenic solvent and some o the paraffinic solvent. The separation of parainic constituents from naphthenic constituents cannot be made completein a commercial operation, but the extracting treatment produces fractions respectively richer in paraffinic constituents and naphthenic constituents than is the ori al oil.

While the oil and solvents are in contact and prior to the separation into layers above mentioned, the desired dissolving of the constituents of the oil in the solvent or solvents may be effected by heat or agitation or both. Prior to the separation it is referable that the temperature should be su ciently high to promote the solvent action of the solvents upon the constituents of the oil, but during the separation it is desirable that the tem- 'aration, but the tem perature should be such as will promote such separation. Low temperatures promote seprature should not be so low as to effect solldication of any of the solvents. Moreover, in the treatment of waxcontaining oil the mixture of solvent and oil should at some time before separation possess a temperature at which the wax is all in liquid state, but the separation may be made thereafter at a tem erature at which a part of the wax is solidi ed. The presence of the paraflinic solvent permits the wax present to precipitate in particles separate from each other and from the oil, giving a mixture Which is fluid and in which the oil is free and ready to be acted upon. Thus the oil may be mixed at a temperature above the melting point of the oil, with a portion of either of the solvents that has not been cooled or has been warmed; and after the mixture is cooled it may be introduced to the action of counterflowing solvents which are at a temperature which promotes separation.

in the practice of this invention, the lighter is the paraflinic solvent, the greater is the specific gravity difference between the solution of parainic fraction and the solution of naphthenic fraction, and the greater is the tendency for separation of the solutions to occur; and the extraction operations will be conducted under such conditions of temperature and pressure, consistent with the foregoing, that the solvents employed are in liquid phase.

ln the practice of this invention, a batch extraction step or a continuous extraction step may be repeated as often as may be necessary to impart to the resulting products the paratiinic and na hthenic characteristics respectively desire for those fractions, or a continuous extraction step may be extended for a similar reason.

Thus, a feature of this invention is that the oil to be treated, which may be a distillate or a residue and may or may not have previously been refined or dewaxed, may be subjected simultaneously to contact with cresylic acid and a parallinic solvent.

A further feature of this invention is that cresylic acid alone may be caused to be capable of eiecting division in fractions respectively more parailinic and more naphthenic an oil which would not otherwise separate into two lavers when treated with cresylic acid alone. In accordance with this feature of this invention the oil is first contacted with cresylic acid alone. The solution of oil constituents in cresylic acid is then extracted with a paraiiinic solvent as above set forth, the oil constituents thus being simultaneously contacted wth both parafiinic and naphthenic solvents. The parali'inic solvent and oil constituents in solution therein is then separated from the naphthenic solvent which contains naphthenc constituents in solution, and freed lli) of parailinic solvent. The parainic constituents so obtained, and such naphthenic solvent and constituents as are contained therein, are then introduced to the oil ilowin to contact with the cresylic acid. The para inic oil constituents so added to the oil to be treated render that oil mixture capable of being divided by cresylic acid alone into'a parainic fraction and a solution of oil constituents in cresylic acid, which fraction and solution separate readily into two layers. The upper la er of this separation is freed of cresylic aci and constitutes the desired paraliinic fraction. Apparently the increasing of the concentration of paraiiinic constituents in the original oil renders it separable by use of cresylic acid alone when it would not otherwise be separable by that solvent alone.

The naphthenic and paralinic solvents may be used in widely varying proportions, the proportions found eifective in practice being one ,to three parts by weight of naphthenic solvent and one toV three parts by weight of parainic solvent to each part of oil to be treated. In view of the wide variations in the properties of oils from different sources, the most economical proportions which produce fraction of desired character should be determined by test of the .oil to be treated.

Moreover, it is contemplated that in the practice of this invention the eli'ectiveness of cresylic acid or components thereof as naphthenic solvents may be increased b mixing therewitha suitable proportion o solvents which have a selective solvent power and definite selectivity for naphthenic constituents and a limited solvent power for mineral oil constituents, and dissolve preferentially asphalts and those constituents ofthe oil which are of higher molecular wei ht. Examples ofsuch solvents are sulphur dloxide, furfural, pyridine, and aniline, and inasmuch as the preferentially dissolve asphalte and constituents of higher molecular weight but have a limited solvent power for mineral oil, they do not have that tendency to be miscible in all proportions with mixed base oil of high asphalt content, which tendency is possessed by dinitro-aromatic solvents.

Fig. 1 is a ilow sheet indicating the steps in the direct treatment of oil in accordance with this invention; and

Fig. 2 is a How sheet indicating the steps in the modified procedure above mentioned.

While the invention may be carried out by the treatment of separate batches of oil, there are indicated in Fig. 1 the steps whereby continuous treatment of mixed base oils may be effected. The oil to be treated which may be either a distillate or a residue, is contacted with cresylic acid or with one or more of its components at a temperature which causes the mixture to separate into layers. In the procedure illustrated, the untreated oil is continuously introduced into a contacting chamber operation preferably at an intermediate level and cresylic acid or one or more of its components is introduced into that chamber at a suitable rate at an upper level thereof and from a similar level there is withdrawn paralinic fraction A while from a lower level there is withdrawn naphthenic fraction A which is passed into a second contacting operation, preferably at an upper level thereof, into which propane is introduced at a suitable rate, preferabl at a lower level thereof, while there is wit drawn therefrom naphthenic fraction B and parainic fraction B which is continuously returned to the Erst contacting operation, preferably at a lower level thereof. Parailinic fraction A is treated for the removal of propane as by the reduction of the pressure upon the fraction or by the application of heat or by both of such steps. e propane is passed to propane storage while the residue of parailinic raction A is subjected to heat to effect distillation therefrom of the cresylic acid which is passed to cresylic acid stora The residue of the paraflinic fraction constitutes the desired parailinic oil. The contacting ste to which is introduced naphthenic fraction and ropane, is so conducted as to effect counterow with the result that the propane removes paranic constituents from naphthenic fraction A and carries them back to the main contacting operation, thus providin in the main contacting operation a counterow of parailinic and naphthenic solvents, to a mid oint of which the oil is introduced. Nap thenic fraction B is treated for the vaporization of propane as by reduction of pressure or application of heat or both of such steps, an the propane is passed to propane storage while the residual mixture is subjected to distillation for the removal of cres lic acid, the residue of na hthenic fraction constitutin the desire naphthenic oil. Contacting c ambers employed are preferably packed to promote agitation and contacting and they may be separate as indicated in the drawing or oined together.

fer-ring to Fig. 2 of the drawing, the oil to be treatd 'is first contacted with cresylic acid; and t e cresylic acid containing oil constituents in solution is then passed into contact with pro ane or other paralinic solvent which e ects a washing of the heavy fraction of the first contacting step. The resulting solution of paraiinic constltuents and of small quantities of naphthenic constituents and cresylic acid in the paranic solvent separates readily from the solution of aramnic solvent and then added to the oil li owing to the original contacting apithenic constituents in cresylic acid.

` amnic fraction step for immediate contact with cresylic acid alone. The treatment with cresylic acid then leaves a substantial paranic fraction undissolved and that parainic fraction forms an upper la er and is removed and is freed from cresyllc acid and constitutes the desired parallinic oil. The naphthenic fraction, after treatment with the araiinic solvent and removal of the para ic solution, as above stated, is treated for removal of solvents and constitutes the desired naphthenic fraction.

The pressures and temperatures necessary in order that solvents which are in vapor phase at normal temperature may be maintainedin liquid phase during use may be determined by reference to existing pressure and temperature tables.

In the practice of this invention, the arroduced is more para ic than the origina oil and the naphthenic fraction produced is more naphthenic than the original oil, and those two fractions are respectively more paranic and more naphthenic than any fractions obtained by the use of cresylic acid alone.

The araiiinic fraction may be subjected to any esired treatments such as acid treatment, clay treatment and dewaxing for the purpose of providing finished lubricants, it being desirable in some cases to treat the paraiinic oil with a caustic soda solution, e. g. 5%, for the removal of traces of cresylic acid before such further treatment. Herein the expression naphthenic constituents includes asphaits and mixtures of asphalte and naph- 'iiiieuic oils.

its a specific example of procedure in accsrdance with this invention, a residue obtained from Mid-Continent petroleum and. having an A. P. I. gravity of 21.7, a Saybolt `Clniversal viscosity of 148 seconds at 210 F. and a viscosity-gravity constant of 0.845, was treated in continuous counter-flow contacting chambers at a temperature of 24 F. using two pounds of commercial cresylic acid and two ounds of propane per pound of original oil, and the resulting products had, after removal of the solvent, the following characteristics:

Naph- Unlisted on I ou thenlc oil Bpecle gravltygl'-.-.... m ma l'o Viscosity S.U. at 210 l 148.0000 9&0000 460. 000 Viscosity-gravity constant 0. 846 0. wl 0. 941 Yield volume 70. 8 2B. 2

of the naphthenic fraction is considerabl greater than that of the original oil an greater than the viscosit -gravity constant of such markedly napht enic or asphaltic base lubricating oils as oils obtained from the Gulf. Cpast and California.

Th"procedure wherein paraiiinic and naphthenic solvents are simultaneously employed and the advantages thereof are more at length set out in my co-pending application, Serial No. 623,483, filed July 20, 1932.

It is intended that distillates and residue, refined or unrefined, maybe treated in accordance with this invention, this invention being of special importance in the treatin of lubricating oils for the improvement o the characteristics thereof. It is to be understood that this invention is not to be limited by any theory of operation expressed or by any example given and that it includes all modifications and variations falling within the appended claims.

I claim:

1. In the art of refining'mineral oii comprising naphthenic and parainic constituents, the step com rising extract the oil, in the presence o an added liq having greater solvent power for paraiiinic constituents of the oil than for naphthenic constituents thereof, with cresyllc acid, the said paratiinic solvent and the cresylic acid being adapted to form a two liquid phase solvent system.

2. In the art of refining mineral oil comprising naphtnenic and parailinic constituents, the step comprising extracting the oil, in the presence of an added liquid having greater solvent power for paranic constituents of the oil than for naphthenic constituents thereof, with one of the group of substances consisting of orthocresoi. metacresol.

paracresol, phenol, xylenol, and a mixture of two or more thereof. the said paradinic solvent being adapted to form separate layers with any of the said group of substances.

3. In the art of refining mineral oil cornprising naphthenic and parailinic constituents, the step comprising extracting the oil, in the presence of an added hydrocarbon solvent therefor having a boiling range substantially below the boiling point of the oil, with cresylic acid, the said hydrocarbon solvent and the cresylic acid being adapted to form a two-layer solvent system.

4. In the art of refining mineral oil comprising naphthenic and paraiinic constituents, the step comprising extracting the oil, in the presence of an added hydrocarbon solvent therefor having a boiling range substantially below the .boiling point of the oil, with one of the group of substances consisting of orthocresol, metacresol, paracresol, phenol. xylenol, and a mixture of two or more thereof, the said hydrocarbon solvent being adapted to form a two-layer solvent liu lli

IBI

system with any of the said group of substances.

5. In the art of refining mineral oil comprisin naphthenic and parainic constituents, t e step compris' extracting the oil in the presence of an a ded hydrocarbon o the group consisting of ethane, propane, butane, pentane, natural gasoline, low endpoint naphtha, and a mixture of two or more thereof, with cresylic acid, said added hydrocarbons and cresylic acid being adapted to form a two-layer solvent system.

6. In the art of refining mineral oil comprisingA naphthenic and paraiinic constituents, t e step comprising extracting the oil, in the presence o f an added hydrocarbon of the group consisting of ethane, propane, butane, pentane, natural gasoline, low end oint naphtha, and a mixture of two or more t ereof, with one of the group of substances consisting of orthocresol, metacresol, paracresol, phenol, xylenol, and a mixture of two or more thereof, said added hydrocarbon being adapted to form a two-layer solvent system with each of orthocresol, metacresol, paracresol, phenol, xylenol or a mixture of two or more t ereof.

7. In the art of refining mineral oil comprising. naphthenic and paraiinic constituents, the step comprising extractin the oil, in the presence of a petroleum nap tha previously extracted with a solvent having greater solvent power for naphthenic than or paraiiinic hydrocarbons, with one of the group of substances consisting of orthocresol, metacresol, paracresol, phenol, xylenol, and a mixture of two or more thereof.I and adapted to form a two-layer solvent system with the said extracted petroleum na htha.

8. In the art of refining mineral oi cornprising naphthenic and parailinic constituents, the'step comprising extracting the oil, in the presence of liquid paraiiinhydrocarbons having a boiling range lower than the iling point of the oil, with cresylic acid, the said liquid parain hydro-carbone and cresylic acid being adapted to form a twolayer solvent system when contacted with each other.

9. In the art of refining mineral oil comprislngl naphthenic and parainic constituents, t e stepjcomprising contacting the oil with cresylic acid, and contacting the solution of oil constituents in cresylic acid with a solvent having greater solvent power for parafiinic than for naphthenic constituents of the oil, the said cresylic acid and paraiiin solvent being ada ted to form a two-layer solvent system w en contacted with 4each other.

10. In the art or refining mineral oil comprisin naphthenic and paraiiinic constituents, t e step comprising contacting the oil with cresylic acid, and contacting the oil not dissolved thereby and the solution thereby formed with a solvent having greater solvent power for paraiinic than for naphthenic constituents of the oil, said cres lic acid and paraiiin solvent being adapte to form a two-layer solvent system when contacted with each other.

11. In the art of refining mineral oil comprisin naphthenic and paraiinic constituents, t e step com rising contacting the oil with cresylic aci contacting the solution of oil constituents in eres lic acid with a solvent having greater so vent power for paraiinic than for naphthenic constituents of the oil, and passing the solvent and oil dissolved thereln into the first-mentioned contacting step, said cresylic acid and parailin solvent being -ada ted to form a two-layer solvent system w en contacted with each other.

12. In a process of 'producing lubricating oil, the steps comprising extractm a residue of Mid-Continent petroleum wit cresylic acid in the presence of a solvent having greater solvent power forparaiiinic than for naphthenic constituents of the oil, and separating said solvent and cresylic acid from the resulting fractions, said cres lic acid and paraffin solvent being adapte to form a two-layer solvent system when contacted with each other.

13. In a process of producing lubricating oil, the step comprising extracting the residue of a Mid-Continent petroleum with cresylic acid in the presence of an added parainic solvent to produce fractions of the 10 oil respectively richer in paraiiinic and naphthenic constituents of the oil, said cresvlic acid and paraiin solvent being adapted to form a two-layer solvent system when contacted with each other.

14. In the art of refining mineral oil comprising naphthenic and paraflinic constituents, the steps comprising contacting the oil with a solvent having greater solvent power for paraiiinic than for naphthenic constituents of the oil, and contacting the resulting solution of oil constituents with cresylic acid, said cresylic acid and parain solvent being adapted to form a two-layer solvent system when contacted with each other.

15. In the art of refining mineral oil comprising naphthenic and paraiiinic constituents, the step comprising contacting the oil with cres'ylic acid, contacting the solution of oil constituents in cresylic` acid with a solvent having greater solvent power for paraiiinic than for naphthenic constituents of the oil, separating the solvent and substances in solution therein from the remainder of the solution of oil constituents in cresylic acid, removing the solvent from the substances in solution therein, and returning said substances to the oil passing to the iirst-mentioned contacting step, said cresylic acid and paraiiin solvent being adapted to form a two-layer solvent system when contacted with each other.

16. In the art of refining mineral oil, the step comprising extractin the oil with a mixture of cresylic acid an sulphur dioxide in the presence of a solvent havin greater solvent power for parafinic than or nephthenic constituents of the oil, the said mixture of cresylic acid and sulphur dioxide, when contacted with the said paraiinic solvent, being adapted to form a two-layer solvent system.

In testimony whereof, I have signed my name to this s ecification.

ALCOLM H. TUTTLE.

CERTIFICATE OF CORRECTION.

Patent No. 1,912, 349.

May 30, 1933.

MALCOLM H. TUTTLE.

lt is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page l, line 34, for "hydrocarbon" read "hydrcgen"; and line 36. for "suitable" read "stable"; page 6, line 61, claim 10, for "or" read "of"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 25th day of July, A. D. 1933.

(Seal) M. J. Moore.

Acting Commissioner of Patents.

two-layer solvent system when contacted with each other.

16. In the art of refining mineral oil, the step comprising extractin the oil with a mixture of cresylic acid an sulphur dioxide in the presence of a solvent havin greater solvent power for parafinic than or nephthenic constituents of the oil, the said mixture of cresylic acid and sulphur dioxide, when contacted with the said paraiinic solvent, being adapted to form a two-layer solvent system.

In testimony whereof, I have signed my name to this s ecification.

ALCOLM H. TUTTLE.

CERTIFICATE OF CORRECTION.

Patent No. 1,912, 349.

May 30, 1933.

MALCOLM H. TUTTLE.

lt is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page l, line 34, for "hydrocarbon" read "hydrcgen"; and line 36. for "suitable" read "stable"; page 6, line 61, claim 10, for "or" read "of"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 25th day of July, A. D. 1933.

(Seal) M. J. Moore.

Acting Commissioner of Patents.

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