US2158360A - Manufacture of lubricating oil - Google Patents

Description

May 16, 1939.

r-l'. x. GovERs MANFACTURE OF LUBRICATING OIL Filed March 29, 1.932

INVENTOR FRANCIS "X.GovERs lATTORNEY Patented May 16, 1939 UNITED S'TATES Pli'rslv'r"v oi-Fics 2,158,360 MANUFACTURE or LUmcA'rmG. om

Francis X. Govers, Vincennes, Ind., assigner t -Indian Refiningcompany, Lawrenceville, Ill.,

corporation of Maine Application Maren 29,1932, serial-'Na 6071.887

i4 claims. (ol. 19e- 13) plates a process of manufacturing lubricating oils having a low pour and cloud test, low sulphur content, low Conradson carbon content, a relatively high viscosity index and free from lbodies of little or no lubricating value. v

Low pour test in a lubricating oil denotes an oil, as Iused in internal combustionl engines, possessing the characteristics of'easy starting in cold weather and readiness of flow suiiicient to respond to methods of circulation so as to immediately reach all parts necessary to be lubricated. y

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.

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 such carbon as may be deposited is of a ilocculent nature, having little or no tendency to adhere to the piston head or cylinder walls. High Conradson carbon content is characteristic, for example, of l residual oils, or oils not redistilled under low absolute pressure, and is .characteristic of oils having desired high viscosity index, as ordinarily produced heretofore. The viscosity index of a given oil is readily determined by resorting to the method of Dean and Davis, published on pages 618-619 of the 1929 issue of Chemical and Metallurgical Engineering. Lubricating oils of high viscosity index are characterized by having a relatively narrow increase in viscosity with decrease in temperature. Such' oils have the propertyof 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 index and fairly high sulphur content. On the other hand, lubricating oils, as ordinarily made from paraffin-base crudes Efforts to reduce the sulphur content of. lubricating fractions to a desirable degree by.'v

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 of the Pennsylvania type, as well as those derived from mixed base crude sources, are diiiicult to refine without undue lossv and impairment of their lubricative value. In any case, it is diiiicult, by methods now employed, to reduce the sulphur content Vof lubricating oil fractions to the desired point', regardless of their crude 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 ofover-rening due to the use'of this method f refining with its consequent impairment' of lubricating value due to over-relinement. Sulphur 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 parain type, has not been successful from the standpoint of producing a product having the desired high viscosity index, low pour test and other characteristics. l y

I have discovered that'by the use of the methods herein disclosed lubricating oils of any desired viscosity index and scale of purication, coupled with low pour test andlow cloud test, can be made from mixed-base or paramn-base crudes, and the oils so produced are characterized further by low Conradson carbon v'and-low sulphur content. v these desired qualities does not depend on meth- The obtaining of oils having ods involving redistillation or acid treatment. The invention comprises mixingwith a waxbearing fraction of mineral oil asolvent liquid havingl a substantial solvent action upon the fraction at temperatures of around 90 F., and at a temperature ofaround 0 F. having substantiallyv complete solvent action upon v'the naphthene-like bodies and otherb constituents of the fraction which are characterized by having a relativelyl low viscosity index, but substantially no solvent action upon the wax and the par'afnic bodies which have .a relatively high viscosity index. Such a solvent liquid may, for example, comprise a' mixture of liquid sulphur dioxide and an organic solvent liquid such as benzol or one of its homologs, or a derivative thereof such as monochlorobenzol. 1

mixture. The precipitated material is then separated from the cold mixture either by gravity settung or by filtration, and the mother liquor j removed.

ing a viscosity of 70 Saybolt Universal seconds at The lseparated .mass of solid, semi-solid and precipitated hydrocarbon material is advantageously washed with an additional quantity of the same cold solvent liquid with which the fraction wasoriginally mixed for the purpose of washling out remaining traces of mother liquor.

'Ihe washed precipitate, while maintained in a cold condition,`is then subjected to a further- Lwashing action with a solvent liquid, or mixture of solvent liquids,'having a selective solvent action between the solid paraffin wax and the semi-solid or associated particles of precipitated oil. A selective solvent suitable for this purpose may advantageously comprise a mixture, in different propor- Qtions, of the saine solvent liquids mentioned above, or, on the other hand, may comprise a mix- 'ture of benzol or one of its homologs with a ketone, such as methyl ethyl ketone, for example. In any case, the solvent mixture is such that it is adapted to dissolve or extract from the mass those precipitated hydrocarbons or particles of oil possessing desirable lubricating qualities while leaving undissolved the solid paraiiln wax.

'Ihis washing or extraction .process may be carried to any desired point to leave as insoluble matter a product approaching either petrolatum,

an easily sweatable wax or else a relatively highmelting point waxrequiring no sweating operation to make it marketable.

The resulting solution containing the oil dissolved from the precipitated mass is then subjected to evaporation in order tovremove the sol-J vent.,for reuse and recover the dissolved oil. The oil recovered in this way from the selective solvent washing of the precipitated mass of solid and semi-solid hydrocarbons possesses superior lubricating qualities.: particularly for internal combustion engines, .on account Aof its low pour test and relatively at viscosity temperature relationship, as indicated by its relatively high viscosity index. g

-As anl example in carrying out my invention. Untreated, vacuum distilled, wax distillate havt, 210 Fjwith a pour test of 80 Frand a sulphur filtering surface withinthe filter in the form of a iilter cake, or kept in suspension between the filtering members, while the illtrate comprising solvent and dissolved'liquid hydrocarbons of substantially the type possessing properties characteristic of the naphthene hydrocarbons is `withdrawn from the filter.

The resulting filter cake, or suspended precipi- ,tate, comprises solid hydrocarbons and particles of oil insoluble in, andimmiscible with, the cold sulphur dioxide-benzol solvent mixture. This filter cake is subjected to washing with chilled fresh sulphur dioxide-benzolsolvent mixture, of about the same composition, for the purpose of removing adhering mother liquor,

'This wash solution containing dissolved mother liquor after yleaving the lter can be'mixed with'l the initial filtrate and the solvent removed by evaporation. Theresulting oil will have an A. P.

I. gravity at 12.8, a viscosity of 115 Saybolt Universal seconds at 210 F, and a low viscosity index,

for example '-25 or below.

The washed ltercake is then subjected to a.k furtherpwashing action by passing through the l lter a cold solvent solution composed of about equal parts of benzol and methyl-ketone chilled to about 10..F. 'I'his solvent mixture exerts substantially nosolvent action on the solid par; p amn' wax constituents of the cake but has a sub# stantially complete solvent action upon. the rewhich were insoluble in the initial solvent solution. This latter solvent therefore` extracts or 'maining hydrocarbon constituents of the cake removes from the lter cake, liquid hydrocarbons oxide-benzol solvent and which possess. the desired properties of relatively low speciiicgravity (high A. P. I. gravity) and relatively highviscosity index coupled with low pour test.

This solution is evaporated to remove the solvent liquid and to recover the dissolved oil ,which, after removal of the solvent, will have an A. P. I. gravity of about 26,'a viscosity index of about 85, with a Saybolt Universalviscosity of about 63 seconds at 210"v F. and a pour test of 0 F. or below. l

The following example illustrates another method of-carrying out my invention employing a solvent mixture comprising liquidsulphur dilwhich were insoluble in the original sulphur distituents insoluble in the chilled mixture,followv' ing which it may be introduced to the same type of filter means discussed above to form a filter cake or suspended precipitate comprising solid hydrocarbons and particles of oil insiluble and immiscible with the cold sulphur dioxide-monochlorobenzol `solvent mixture in the proportions I 'I'his filter cake or precipitate is subjected to Washing by passing through the filter chilled fresh sulphur dioxide-monochlorobenzol solvent mixture, of about same composition initially used, for the purpose of removing adhering mother liquor. The washed solution containing dissolved mother liquor, after leaving the filter, can be 'mixed with the initial filtrate and the solvent removed by evaporation. The resulting oil will have approximately the following characteristics: A.`P. I. gravity of 11.8, a viscosity of 125 Saybolt Universal seconds at 210 F., and a low viscosity index of -30 or below.

The washed iilter' cake is then subjected to a further washing action bypassing through the lter a chilled solvent solution comprising 30% of sulphur dioxide and '70%fmonochlorobenzol chilled to `about -15 F. This solvent mixture exerts substantially no fsolvent action upon the solidparailln wax constituents of the cake, but has substantially complete solvent action upon the remaining hydrocarbon constituents of the cake which were insoluble in the initial solvent solution. This 'latter solvent mixture,therefore,

. extracts or removesvfrom the precipitate, liquid hydib'ocarbons which possess the desired property of relatively low specific `gravity (high A. P. I.

gravity) and relatively high viscosity index coupled with low pour test.

lThe washing step may be repeated using an ture may be used in the chilled condition or itA may be used at high temperatures while maintaining pressure sufficient to keep the sulphur dioxide in a liquid state, and the solution then chilled. This wash liquid, by the addition of the requisite quantity of sulphur dioxide, may subsequently be used as the original solvent mixture for mixing with. fresh oil in the initial step of purification. K

'I'he solution comprising solvent wash liquid and dissolved hydrocarbons extracted from the precipated mass within the filter is subjected to evaporation to remove the solvent liquids. The hydrocarbon liquid. thus remaining is contacted with clay in the proportion of about twenty pounds of clay to the barrel While heating to a temperature of around 500 F. The mixture of oil and clay is subjected to steaming and cooled to 350 F., following which it is ltered to remove the clay. The ltered oil will have approx- 'imately the following characteristics: A. P. I.

gravity of 29.5, a viscosity index ofl 95,a viscosity of 64 Saybolt Universal seconds at 210 F., and a pour test of -10 F.

If it is desired to obtain a -product of still higher viscosity index and higher A. P. I. gravity, the precipitated mass may be'washed or extracted with a mixture of solvent liquids in this proportion, as, for example, a mixture comprising about 45% sulphur dioxide and 55% monochlorobenzol. On chilling to 5 F. and allowing .to separate, the top layer, after removal of the solvent, will be found to have an A. P. I. gravity of about 31.5, a viscosity index of about 105, a Saybolt Universal viscosity of about 62 seconds at 210 F., and a pour test of 0 F. or below. The bottom layer, after evaporation of the solvent, will have an A. P. I. gravity of'about 26.5, a viscosity index of about 76, a Saybolt Universal viscosity of about 68 seconds at 210 F.,v and a pour test ofA 5 F. or below. i

In carrying out this washing step, the temperature of the solvent and/or the proportions of the constituents of the solvent mixture may be varied if desired in order to effect the desired degree of selectivity between the hydrocarbomconstituents to be removed from the filter cake, and those remaining. The solid hydrocarbons remaining on theV lter surface comprise Awax substantially free from liquid hydrocarbons 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, may be pre-l pared by varying the proportions of the solvent liquids and also the temperatures at which the treating steps are carried out.

This 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 param-containing fractions, precipitates, or materials somewhat similar lin nature derived v'in various ways from mineral oils.

Thus my invention is applicabletol the treatment of hydrogenation products resulting from the hydrogenation of carbonaceous materials, or mineral oils including liquid or solid hydrocarbon fractions derived from mineral oils. Hydrogenation products may contain substantial quantities of waxy or paramn material as well as other constituents of relatively low lubricating value. By treating such products in accordance with my inventionnal products of desired characteristics can be obtained.

The invention is not restricted to any particular operating conditions such as that of ternperature and pressure, or the composition of the solvent mixtures employed since these conditions may advantageously be varied depending upon the nature of the fraction undergoing treatment as well as upon the particular characteristics desired in the nal product.

It is'also contemplated in many instances that it may be of advantage to carry on theltration in the presence oi' a comminuted solid iiter-aid material. Such material may be admixed with the chilled mixture of oil and solvent liquid prior a source not shown and introduced toa mixer l wherein it is mixed with solvent also conducted from a source not shown. The solvent comprises annixturepf sulphur dioxide and a-modifying solvent consisting of 50% or 'more of sulphur dioxide.

The resulting mixture is conducted to a chiller 2 and chilled to a temperature of around -l0 F. Thereafter, itis introduced to a lter 3. The ltrate designated as filtrate A and rich in naphthenic constituents, is r moved and conl ducted to a still d wherein the lvent is removed,

leaving extract oil of heavy gravity.

The precipitated mass remaining in the filter 3 in the form of a filter cake, rcomprises wax and normally liquid parainic hydrocarbons. A wash solvent of different composition from that of the solvent used in mixer i is passed through a chiller i2, and introduced to the lter 3. This wash solvent comprises,l for example, a mixture of sulphur dioxide and a modifying solvent containing around 30% of sulphur dioxide. In passing through the filter 3, it dissolves the normally liquid parafnic constituents which leave the filter in the form of a nitrate, designated filtrate B, rich in paraffinic constituents of the oil.

The filter cake remaining in the filter 3 is now rich in wax and is removed to a still wherein the solvent is removed. leaving solvent-free wax. .The filtrate B is drawn oi to a still 6, all or in part. The solvent liquid is removed from the oil, leaving a raffinate fraction, which is conducted to a clay-treating plant 1 to produce a refined oil.

Instead of introducing the ltrate .B to the still 6, it may be conducted through a chiller 8, wherein the temperature of the filtrate is reduced such that upon standing the mixture will separate into layers. 'Ihe chilled mixture is then conducted to a separator` 9 wherein separation f move the solvent and dissolved low 4viscosity index n into layers occurs. The top layer, relatively rich in high viscosity index constituents, is conducted to a still l wherein the solvent is'removed; leaving a raffinate oil of relatively light gravity. This ramnate is conducted tolv the `/clay treating plant 1 previously referred tol The bottom layer of the separator 9, and comprising constituents of lower viscosity index, is drawn off to a still II wherein the solvent is recovered, leaving a rainate oil of relatively heavier gravity. This raiiinate is also conducted to the clay treating plant l.

In the clay treating plant 1, the oil is subjected to the conventional method of treatment involving contact with adsorbent clay in the presence of steam, following which the clay is removed from the oil by filtration.

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.

I claim:

l. The process of manufacturing high viscosity index lubricating oil of 0 F. pour test or lower from wax-bearing mineral oil comprising mixing with the oil a solvent mixture composed of about equal parts of liquid sulphur dioxide and monochlorbenzol, chilling the mixture to around 0 F. or below whereby the relatively high viscosity index constituents together with wax constituents are precipitated, filtering the mixture to remove the solvent and dissolved low viscosity index constituents and forming a filter cake composed of a precipitate of relatively high viscosity index constituents and wax constituents, extracting the precipitate in situ with a chilled mixture of liquid vsulphur dioxide and monochlorbenzol, the monochlorbenzol comprising substantially in excess of around 50% of the solvent mixture whereby the relatively high viscosity index con- -stituents are dissolved and removed from the constituents and forming a filter cake composed of a precipitate of relatively high viscosity index constituents and wax constituents, selectively extracting the precipitate with chilled solvent mixtures of differing proportions of liquidsulphur dioxide and monochlorbenzol, the proportion of monochlorbenzol being in excess of that used in the initial extracting step, whereby fractions of differing viscosity index are obtained, and recovering the solvent from said fractions.

3. The process of manufacturing high viscosity index lubricating oil of zero pour test or lower from wax-bearing mineral oil wherein the oil is rst extracted and then dewaxed, comprising mixing the oil with a solvent liquid mixture composed of liquid sulphur dioxide and monochlorbenzol in proportions with the wax-bearing oil such that the mixture exerts a solvent action substantially only upon the relatively low viscosity index constituents at temperatures of around 0 F., chilling the mixture to a temperature of around 0 F. to separate it into an extract phase .and separated from the wax constituents, re-

moving thelhigh viscosity index constituents dissolved in solvent, and removing the solvent therefrom.

y 4. The process of manufacturing high viscosity index lubricating oil of zero pour test or lower from wax-bearing mineral oil wherein the oil is first extracted and then dewaxed, comprising mixing the oil with a solvent liquid mixture composed ofliquid sulphur dioxide and benzol in proportions with the wax-bearing oil such that the mixture exerts a solvent action substantially only upon the relatively low viscosity index constituents at temperatures of around 0 F., chilling the mixture to a temperature of around 0 F. to separate it into an extract phase comprising low viscosity index constituents dissolved in solvent liquid, and a raffinate phase comprising high `viscosity index oil constituents and wax constituents, removing said rafnate phase, extracting it while maintained at substantially said separating temperature with a chilled mixture of liquid sulphur dioxide and benzol in which the proportion of sulphur dioxide to benzol in the mixture is substantially decreased over that prevailing in the initial extracting stage whereby the relatively high viscosity index oil constituents are dissolvedy and separated from the wax constituents, removing the high viscosity index constituents dissolved in solvent, and removing the sol- -vent therefrom.

5. A process of manufacturing lubricating oil, which comprises mixing a lubricating oil with sulphur dioxide and benzol, separating the extracted oil and the extract, adding a larger pro- 'portion of sulphur dioxideand benzol to the exl tracted oil, the benzol being in greater proportion than the sulphur dioxide', and separating the wax therefrom.

6. A process of manufacturing lubricating oil,

which comprises mixing a wax-bearing lubri-l cating oil fraction containing constituents of relatively high and relatively low viscosity index with sulphur dioxide and a modifying solvent having less'selective action than sulphur dioxide as between high and low viscosity index constituents of the oil, separating the extracted wax-bearing which comprises mixing a wax-bearing lubri cating oil fraction containing constituents of relatively high and relatively low viscosity index with sulphur dioxide and benzol, separating the extracted wax-bearing fraction and the extract containing loW viscosity index constituents, mixing additional'sulphur dioxide and benzol with the extracted wax-bearing fraction, the benzol being in greater proportion than the sulphur dioxide, and separating the wax therefrom.

8. The process of manufacturing low cold test high viscosity index lubricating oil from waxbearing mineral oil which comprises mixing the oil with liquid sulphur dioxide and a modifying solvent having relatively less selective action than sulphur dioxide as between low and high viscosity index constituents of the oil, in such proportions with the oil that the mixture exerts a selective solvent action as between the relatively low viscosity index constituents and the relatively high viscosity index constituents including wax,

l5 forming an extract phase comprising low viscosityindex constituents and a raffinate phase comprising high viscosity index constituents and wax, separating' the extract phase from the raffinate phase,- mixing with said rafiinate phase sulphur 'dioxide and modifying solvent, the modifying solvent being in greater proportion than the sulphur dioxide and such that the solvent mixture has selective solvent action as between wax and liquid hydrocarbons at temperatures of around 0 F., and separating the wax hydrocarbons from.

`the mixture while the mixture is maintained in a chilled condition.

9. A process of manufacturing lubricating oil, which comprises mixing a wax-bearing lubricating oil fraction containing constituents of relatively high and relatively low viscosityindex with sulphur dioxide and an aromatic hydrocarbon selected from the group consisting of benzol and its homologs, separating theextracted wax-bearing fraction and the extract containing low viscosity index constituents, mixing additional sulphur dioxide and aromatic hydrocarbon with the extracted Wax-bearing fraction, the aromatic hydrocarbon being-in greater proportion than the sulphur dioxide, and separating the wax therefrom.

10'. The process of manufacturing low cold test high viscosity index lubricating oil from waxbearing mineral oil wherein the oil is rst' extracted and then dewaxed, comprising mixing the oil with liquid sulphur dioxide and anf aromatic hydrocarbon selected from thegroup consisting of benzol and its homologs, in such proportions with the oil that the mixture exerts a selective solvent action as between the relatively low viscosity index constituents and the relatively high viscosity index "constituents including wax, forming an extract phase comprising low viscosityindex constituents and a rafllna'te phase compris- 55, ing high viscosity index constituents and wax', separating the extract phase from the rafllnate mixing the oil with a solvent liquid mixture composed of a selective solvent liquid having selective action substantially similar to that of liquid sulphur dioxide as between the relatively low and relatively high viscosity index constituents of the oil, and a substantially less yselective solvent liquid in proportion with the wax-bearing oil such that the mixture exerts solvent action substantially only upon the relatively low viscosity index constituents of the `oi1 at temperatures of around 0 F., chilling the mixture to around 0 F. to`

separate it into an extract phase comprising low viscosity index constituents dissolved in solvent, and a raiilnate phase comprising high viscosity index oil constituents, precipitated wax constituents and some solvent, removing said raffinate phase and extracting it while maintained at substantially said separating temperature with a chilled mixture of said selective and' less selective solvent liquids in which the proportion of selective to less selective solvent in'the mixture Y- is substantially decreased over that prevailing in the extracting stage and comprising in part solvent present in the raffinate phase formed in said extraction stage, whereby the oil constituents of relatively high viscosity index and low pour test are dissolved and separated from the wax constituents.

12. The process according to claim 1l, wherein 'monochlorbenzol is the less selective solvent liquid.

13. The process according to-claim 11, wherein the less selective solvent liquid comprises a chlorinated aromatic hydrocarbon having solvent properties for mineral oil corresponding substantially to those of monochlorbenzol.

14./ The process according to claim 1l wherein the finally separated oil constituents of low pour test and high viscosity index are contacted with solid adsorbent material to Aproduce a neutral finished product.

` FRANCIS X. GOVERS.

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