US2044726A - Manufacture of lubricating oil - Google Patents

Description

Patented June 16, 1936 UNITED STATES PATENT OFFICE.

MANUFACTURE OF LUBRIOATING OIL Francis X. Govers, Vincennes, Ind., assignor to Indian Refining Company, Lawrenceville, 111., a corporation of Maine.

/ No Drawing. Application December 24, 1934,

Serial No. 758,941

8 Claims. (61.,196-1'1) This invention relates to the manufacture of lubricating oil from hydrocarbon oils, and more a particularly to the manufacture of high viscosity index, low pour test lubricating oil from waxbearing mineral oils.

In its broadest aspect, the invention contemplates an improved process of treating hydrocarbon oils, particularly paraflin-bearing lubricating fractions of petroleum with solvents to selectively produce therefrom low pour test lubrilates to a process of solvent refining mineral lu-,

bricating oil with liquid sulphur dioxide in the presence of a modifying solvent comprising benzol or 'one of its homologs, or a derivative thereof, such as monochlor-benzoh. The present application relates to a process of solvent refining mineral lubricating oil with liquid sulphur dioxide in the presence of a modifying solvent comprising a dichlorinated aromatic hydrocarb )n such as dichlor-benzene.

Low pour test in a lubricating oil denotes an oil, as used in internal combustion engines, pus,- sessing the characteristics ofj'easy starting in cold weather and readiness of fldw sufiicient to respond to methods of circulation so as to imme-: diately reach all parts necessary to be lubricated.

The presence of sulphur or sulphur-containing bodies in lubricating oil is objectionable on account of the corrosive effect of sulphur upon bearing surfaces and other metal portions of the engine. Efforts to reduce the sulphur content of lubricating fractions to a desirable degree by v methods ordinarily employed have resulted in an over-refined oil with impaired lubricating value.

Lubricating oil having a low Conradson carbon content is desirable since such oil has little tendency to carbonize in the motor, and suchcarbon as may be deposited is of a fiocculent na ture, having little or no tendency to adhere to the piston head or cylinder walls. High Conradson carbon content is characteristic, for example, of residual oils, or oils not redistilled under low absolute pressure, and is characteristic of oils having desired high viscosity index, as ordinarily produced heretofore. 1 I The viscosity index of a given 011 is readily determined by resorting to, the methodv of Dean 5 and Davis, published on pages 618-619 of the 1929 issue ofv Chemical and Metallurgical Engineering. Lubricating oils of high viscosity index are characterized by having a relatively narrow increase in viscosity with respect to temperature. Such l oils have the property of possessing the desired viscosity at elevated temperature with no'great loss of mobility at very low temperature. Lubricating oils, as ordinarily made from naphthene-base crudes, have a low pour and cloud test, low Conradson carbon content, but have a low viscosity indexand fairly high sulphur con- "tent. 0n the other hand, lubricating oils, as ordinarily made from parafiin-base crudes of the Pennsylvania type, have a high pour and cloud test, high Conradson-carbon content and a fairly high sulphur content, depending on the particular crude source. Oils derived from mixed base crudes may fall somewhere between these limits although usually high in sulphur content. Oils 2 of the Pennsylvania type, as well as those derived from mixed base crude sources, are dificult to refine without undue loss and impairment of their lubricative value. In any case, it is difficult, by methods now employed, to reduce the sulphur content of lubricating oil fractions to the desired point, regardless of thencrude source.

The generally accepted method, as used in the art.of refining petroleum lubricants for the removal of sulphur as well as other, undesired constituents, is by the use of sulphuric acid. Much stress has recently beenput on the danger v of over-refining due to the use of this method of refining with its consequentimpairment of lubricating value due to over-refinement. phur dioxide has been proposed as a substitute in the refining art but the use of this solvent by itself in refining in viscous fractions, particularly of the 'paraffln type, has not been successful from the standpoint of producing a product hav- 5 ing the desired high viscosity index, low pour test and other characteristics.

I have discovered that by the use of the meth ods herein disclosed lubricating oils of any desired viscosity index and scale of purification, coupled with low pour test and low cloud'test, can be made from mixed-base'or paraflin-base crudes, and the oils so produced are characterized further by low Conradson carbon and-low sulphur content. The obtaining of oils having these desired qualities does not depend on methods involving redistillation or acid treatment.

More specifically the invention comprises mixing with a wax-bearing fraction of a mineral oil a solvent mixture comprising two or more solvent liquids of diilering solvent properties which, in certain ratios of one solvent liquid to other solvent liquids, has substantially complete solvent action on the'oil at temperatures of around 100-125? F., and at temperatures of around F.

substantially complete solvent action on the liqdex constituents of the'liquid hydrocarbon con- 01 the hydrocarbons.

tent.

The mixture is then chilled to form a precipitate of solid or semi-solid materialcomprising suspended wax or solid hydrocarbons which are insoluble in, and immiscible with, the solvent mixture. The mother liquor is separated from the cold mixture advantageously by filtration. The separated mass of solid hydrocarbons is then washed free of mother liquor containing dissolved oil by additional quantities of chilled solvent liquid oi! approximately the same composition as used in the original mix.

A certain portion of the filtrate from this washing operation may be added to the original filtrate,

the amount 01' liquid so added depending on the amount of dissolved oil contained therein. To the original filtrate or mixture of original filtrate and first wash liquor is then added an additional amount of one of the component solvents of the solvent liquid mixture to alter the percentage composition of the components of the solvent mixture in an amount sufilcient to afiect the solvent capacity 01' the solvent mixture and causes. separation between soluble and insoluble constituents This mixture is chilled to effect a sharp and rapid separation into two layers, the upper layer containing oils characterized by relatively high viscosity index, and the lower layer containing oils characterized by relatively low viscosity index. The amount and character 01' the separation is influenced-by the amount of alteration in the percentage composition of the components comprising the solvent liquid mixture.

I have found that a suitable solvent liquid mixture comprises a mixture of liquid sulphur dioxide and dichlor-benzene, and in particular a mixture composed of liquid sulphur dioxide and eitherortho or meta dichlor-benzene. A solvent composed of sulphur dioxide and a mixture comprising the isomers of dichlor-benzene may be employed. Para dichlor-benzene which has arelatively high melting point may form a constituent part of the solvent mixture when used in solvent mixtures where it forms a small part of themixture.

The selective solvent action of a mixture of the solvents upon the various constituents of a hydrocarbon oil fraction is readily altered by varying. the proportion of the solvent components or the mixture.

dioxide and 70% As an example in carrying out the above invention:

200 gallons o1 untreated vacuum distilled wax distillate having a viscosity of '70 Saybolt Universal seconds at 210 F. with a pour test of 80 F. and a sulphur content of about .4% derived from a semi-paraffin base crude, is mixed with 600 gallons of a solvent liquid comprising 30% sulphur dioxide and 70% ortho dichlor-benzene, the mixture is chilled to F. to precipitate the wax-like or solid hydrocarbons and introduced to filtering means described in my copending application, Serial No. 585,844, for "Method of and apparatus for filtration, filed January 11, 1932,

wherein the solid hydrocarbons are separated from the liquid to produce a filter cake.

A wash solvent liquid comprising sulphur ortho diehlor-benzene and chilled to -15 F. is introduced to the press to wash out of the filter cake the adhering mother liquor. The first portion of the filtrate resulting from this washing, which will contain a substantial quantity of dissolved oil may be mixed with the original filtrate. while the remaining portion may be used to mix with fresh untreated wax distillate to be treated in. the same manner as the original "material as above described.

The slurry remaining in the filter press is then removed and the bulk of the admixed solvent filtered off advantageously by filtering this slur- -ry in a filter means such, for example, as de-- scribed in my U. S. Patent No. 1,920,126, for Filtration, issued July 26; 1933. The solvent retained in the resulting filter cake is evaporated from the wax and the wax contacted with clay or finished up in the usual manner.

I The wax in the above example will amount to approximately seven and'one-half per cent of the original wax distillate and after removal of the solvent by evaporation, steaming in the presence of clay and contact filtering, the wax will be white and have a melting point, without sweating, of about 136 F. To the mixture of original filtrate and initial portion of wash liquor is added liquid sulphur dioxide chilled to a temperature of 10 F. This additional sulphur dioxide should be suflicient in amount to bring the ratio of sulphur dioxide to ortho dichlor-benzene up toabout equal-volumes oi! each.

The mixture is well stirred and allowed to settle and stratify.- The top layer will comprise low gravity, relatively high viscosity index oils, while 'the lower layer/comprises high gravity, low viscos- The fraction of relatively high viscosity oil may be contacted with clay and filtered, and is then ready for use as a so-called wide cut, or it may be fractionated by vacuum distillation to produce cuts 01' narrower distillation range.

On the other hand, this relatively high viscosity material may be still further improved or refined by dissolving in ortho dichlor-benzene, cooling the mixture to 0 F. and adding chilled liquid, sulphur dioxide in about the same proportion as the dichlor-benzene. The mixture is well stirred,

chilled to --10 F. and allowed to settle. The oil in the top layer, after removal of the solvent, contacting a'nd steaming in the presence bf clay and contact filtering, will have the following approximate characteristics: Gravity 30.6, viscosity of 611 Saybolt Universal seconds at 210 F., viscosity index 95, Conradson carbon .015, and sulphur .1, with a pour test of F.

As an additional example in carrying out the tion of the wash filtrate being mixed with the original filtrate. T

To this mixture of original filtrate and wash liquor is added chilled sulphur dioxide sufficient stratify.

to give a solvent mixture of 60% sulphur dioxide and 40% dichlor-benzene. The mixture is stirred well, chilled to F. and allowed to settleand The separated bottomlayer is drawn off. the

, solvent evaporated and the oil recovered. There will be recovered an oil having a gravity of approximately 12.4 A. P. I. and a viscosity index of approximately 32.

The separated top layer is mixed with a chilled mixture of ortho dichlor-benzene and sulphur dioxide comprising about 40% sulphur dioxide and 60% vdicl' lor-benzene, welltirred, chilled to 10 F. and allowed to-separa e. The bottom layer is drawn off, the solvent evaporated andthe contained oil contacted at' 500 F. with 20 pounds of clayto the barrel. This contacting may be carried out in the presence of steam. The

31.1 A. P. I., viscosity 63 Saybolt Universal seconds at 210 F., viscosity index 102 pour test 5 F.', Conradson carbon .012, sulphur .09.

The solvent can be recovered from the refined oil by dis illation or other means. The sulphur dioxide component may be readily removed by flash distillation while the dichlor-benzene may be removed by distillation under low absolute pressure. It is contemplated also that instead of re-.

moving the high boiling solvent liquid from the oil by distillation it may be removed by washing with a suitable solvent liquid adapted to dissolve the solvent and any retained extract phase material remaining in the refined oil. After removal of the wash solvent anddissolved material, the remaining refined oil can then be finished up by contacting witha solid adsorbent material in the presence of steam and at elevated temperature, in accordance with the customary clay contacting type of treatment.

,The invention is not limited to the production.

of ,final products having the particular characteristics of those described above. Products of differing characteristics, as desired, maybe prepared by varying the proportions of the solvent liquids and also the temperatures at which the 5 treating steps are carried out.

Furthermore, the invention is not limited to the treatment of wax distillate such as given in the examples herein but is adapted to the treatment of other parafiln-containing fractions, pre- 10 cipitates or materials somewhat similar in nature 1 derived in various ways from mineral oils.

Thus my invention is applicable to the treat-- ment of hydrogenation products resulting from the hydrogenation of carbonaceous materials, or mineral oils including liquid or solid hydrocarbon fractions derived from mineral oils. Hydrogena tion products may contain substantial quantities of waxy or paraffin material as well as other constituents of relatively low lubricating value.

By treating such products in accordance with my invention, final products of desired characteristics can be obtained.

' The invention is not restricted to any particular Y operating conditions such as that of temperature,

or the composition of the solvent mixtures employed'since these conditions may advantageously v be varied, depending upon the nature of the fraction undergoing treatment as well -as upon the particular characteristics desired in the final product. 1 v

It is also contemplated, in many instances, that it may be of advantage to carry on the filtration step in the presence of a comminuted solid filter-aid material. Such material may be ad- 5 mixed with the chilled mixture of oil and solvent liquid prior to introduction to the filtering means.

While in the foregoing examples the oil is mixed with a mixture of sulphur dioxide and ortho dichlor-benzene, it is contemplated that the wax 40 bearing oil may first be dissolved in the ortho -dichlor-benzene' alone and then the cold liquid sulphur dioxide addedtothe mixture.

Obviously. many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

Iclaim:

1. The method of dewaxing wax-bearing mineral lubricating oil for the production of oil having a pour test of 0 F. and below, which comprises mixing the wax-bearing oil with a solvent mixture comprising liquid sulphur dioxide and dichlor-benzene containing less than 50% sulphur dioxide in proportions such that at temperatures of 0 F. and below the mixture has sub-' stantially complete solvent action on the liquid hydrocarbon constituents and substantially no solvent action on the solid hydrocarbon constituents of the oil, chilling the mixture to a tem- .--perature of 0 F. and below to precipitate the solid hydrocarbon constituents and separating the thus precipitated solid hydrocarbon constituents from the cold mixture to thereby produce oil ortho dichlor-benzene in proportions such that r at temperatures of 1''. and below the mixture hassubstantially complete solvent action on the duce oil which, after removal of the solvent, has

a pour test of 0 F. and below.

3. In the manufacture of lubricating oils of desired high viscosity index from mineral oil containing constituents of differing viscosity indices, the method comprising extracting the'oil with a mixture oi',sulphur dioxide and dichlor-benzene containing up to about 50% dichlor-benzene, forming an extract phase comprising low viscosity index constituents oi the oil dissolved in the solvent and a raflinate phase comprising relatively high viscosity index constituents of the oil, and separating the two phases.

4. In the manufacture of lubricating oils of desired high viscosity index from mineral oil containing constituents of difiering viscosity indices, the method comprising extracting the oil with a solvent mixture comprising liquid sulphur dioxide and ortho dichlor-benzene, the dichlor-benzene comprising up to about 50% by volume of the solvent mixture, forming an extract phase comprising low viscosity index constituents oi. the oil dissolved in the solvent and a raflinate phase comprising relatively high viscosity index constituents ity index lubricating oil having low pourtest from wax-bearing'mineral oil, the method which comprises mixing with the oil a solvent liquid mixture composed of liquid sulphur dioxide and dichlorbenzene containing less than about 50% sulphur dioxide in proportions such that at temperatures of 0 F. and below the solvent mixture has substantially complete solvent action on the liquid 3 hydrocarbon constituents and substantially no solvent action on the solid hydrocarbon constituents of the oil, chilling the mixture toa temperature of 0 F. and below to precipitate the solid hydrocarbon, removing the solid hydrocarbons thus'precipitated, increasing the proportion of liquid sulphur dioxide to dichlor-benzene in the dewaxed mixture, separating the resulting .mixture into a solvent phase containing low.

viscosity index constituents of the oil dissolved in the solvent, and an oil phase comprising relatively high viscosity index constituents of the oil, and separating the two phases.

6. In the process of separating from wax-bearing mineral lubricating oil a low pour test fraction having a viscosity index oi around 100 and above, the method which comprises dewaxing the oil with a solvent mixture comprising liquid sulphur dioxide and dichlor-benzene and containing less than about 50% sulphur dioxide, extracting 5 the dewaxed mixture in the presence or a mix- I ture of sulphur dioxide and dichlor-benzene containing up to about 50% dichlor-benzene having selective action as between naphthenic and parafflnic hydrocarbons and having as a component part 01' such solvent mixture the solvent liquid retained in the dewaxed mixture, separating from the mixture a rafllnate phase comprising paraiilnic oil and some solvent, subjecting the separated rafflnate phase to further extraction in the presence of sulphurdioxide and dichlorbenzene and separating therefrom a fraction comprising low pour test oil of desired high viscosity index.

7. In the process ofseparating from wax-bearing mineral lubricating oil a fraction of low pour test having a viscosity index of around 100 and above, which comprises mixing the oil with a mixtureof liquid sulphur dioxide and ortho-dichlorbenzene containing less than 50% sulphur dioxide and in proportions such that the mixture has selective action as between wax and oil at temperatures of the order of 0 and below, chilling the mixture to separate the wax, removing the wax from the cold mixture, adding further cold liquid sulphur dioxide to the chilled dewaxed mixture, separating therefrom a. rafiinate phase comprising paraflinic oil and some solvent mixture, subjecting the separated rafiinate phase to further extraction in the presence of liquid sulphur dioxide and dichlorbenzene in proportions such that low pour test parafllnic oil of desired high viscosity index is separated therefrom, and removing the solvent from the thus separated oil.

8. In the process oi? separating from dewaxed 9 mineral lubricating oil a fraction having a viscosity index of around 100 and above, themethod which comprises mixing the oil with a mixture of liquid sulphur dioxide and dichlor benzene containing in excess oi sulphur dioxide 5 and in proportions such that the solvent mixture has selective action as between naphthenic and paraflinic hydrocarbon constituents of the oil, separating from the mixture a raflinate phase comprising paramnic oil and some solvent, sub- 50 4 jecting the separated rafllnate phase to further extraction with a mixture of sulphur dioxide and dichlor-benzene containing less than 50%, sulphur dioxide and in proportions such that oil 01' desired high viscosity index is separated therefrom.

- more x. aovERs.