US2179064A - Refining of oil compositions containing sulphurized fatty esters - Google Patents

Description

Patented Nov. 7, 1939 2,179,064 PATENT OFFICE" REFINING 0F on. COMPOSITIONS com I TAINING SULPHURIZED ra'r'ry ESTERS Herschel G. Smith, swimmer-e, and Troy Lee CantrelLLansdowne, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing.

Application September 28, 1936,

- Serial No. 103,051

17 Claims.

.This invention relates to refining oil compositions containing sulphurized fatty esters, and it comprises methods of refining such oil compositions to remove undesirable impurities, to improve their stability both during storage and in use, and to improve their other properties such as color, viscosity, etc., wherein the oil compositions containing sulphurized fatty esters, advantageously sulphurized mono-esters, are treated o with acid-washed clay or other adsorbent matelight color; all as more fully hereinafterset forth and as claimed.

Certain mixtures of mineral oil and sulphurized fatty oils are well known, such mixtures hav ing been used as cutting oils, etc. sulphurized fatty oils obtained by adding sulphur to a fatty oil, such as lard oil, etc., and heating the mixture for several hours have been frequently used in making such cutting oils. Likewise it is well known that the addition of sulphurized fatty oil to mineral oils imparts extreme pressure charac- 5 teristics to the latter.

It is also well known that by heating fatty oils with sulphur, vulcanized oils which are semisolid or solid at room temperatures may be obtained. In many cases, vulcanized products substantially insoluble or immiscible with mineral oils can be obtained. In the ordinary sulphurization of fatty glycerides, varying amounts of such insoluble or diflicultly soluble sulphurized products are present in the sulphurized oils produced. When the sulphurization is stopped at a stage yielding liquid sulphurized products upon cooling, the presence of minor amounts of the said sulphurized products is not easily detected. Although they are insoluble in mineral oils, they are more or less miscible with the liquid sulphurized glycerides. Sometimes they are colloidally suspended in the liquid sulphurized oil. Also, in sulphurizing fatty glycerides, other byproducts are produced which are more or less corrosive. For these reasons, mixtures of mineral oil and sulphurized fatty oils are not wholly satisfactory for many of the uses for which they would otherwise be highly desirable. For instance, although the sulphurized fatty oil imparts extreme pressure characteristics .to mineral oils, the lubricatingcompositions so obtained are rather corrosive and not sufliciently stable. The mineral 011 being the main constituent of such compositions, the sulphurized fatty glyceride becomes so diluted by the mineral oil that sulphurized products which were initially retained in solution or suspension in the liquid sulphurized fatty oil will sooner or later become precipitated. When such precipitation occurs during the mixing or blending of these oils, the precipitated matter can be detected and may be readily settled out in some cases. However, all of such products are not ordinarily precipitated immediately; rather a gradual further precipitation usually occurs during storage. Even after long storage some of the precipitated sulphurized compounds remain colloidally dispersed in these compositions, imparting a hazy appearance to the product and proclaiming to all that the material is unstable and that its. use is apt to be accompanied by difficulties. Such suspended matter deleteriously affects most lubricating compositions, such as lubricating oils. The sludging properties of the material are not satisfactory when the ordinary sulphurized fatty glycerides have been admixed with a mineral lubricating 011. Because of the various difflculties encountered with mixtures of mineral oils and' sulphurized fatty glycerides, the utilization of sulphurized fatty glycerides as extreme pressure ingredients has not been feasible in commercial practice. Fo the reasons stated, the practice has been to avoid the use of those materials as the ingredients to impart extreme pressure characteristics to mineral lubricating oils.

In contradistinction, sulphurized sperm oils are useful for improving mineral lubricating oils. Carefully sulphurized sperm oils are especially advantageous addition agents for mineral lubricating oils.

It has been found that sulphurized mono-esters of fatty acids, such as sulphurized sperm oil, are quite different from the sulphurized fatty glycerides. The'sulphurized mono-esters are excellent improvement agents for mineral oils and other facture of such improved lubricants is described and claimed in the co-pending patent applications of one of the present applicants. Herschel G. Smith, Serial Nos. 60,355 and 60,357, The improved lubricants broadly claimed in application Serial No. 60,357 are lubricants comprising a major proportion of mineral oil and a minor proportion of an improvement agent which is a sulphurized mono-ester obtainable by reacting sulphur with an unsaturated aliphatic mono-ester of a mono-hydric alcohol and mono-basic acid to form substantially neutral, addition products readily soluble in mineral oils. The improved lubricants containing a sulphurized naturally occurring mono-ester of this type, such as sperm oil, are specifically claimed in application Serial No, 60,355.

In application Serial No. 60,355, there are described methods for producing sulphurized sperm oils wherein the mono-ester is carefully sulphurized to obtain a sulphurized product having a combination of properties rendering it highly advantageous as an improvement agent for lubricating compositions. In those methods, the sulphur is slowly added to the pre-heated oil to effect a gradual sulphurization thereof and to prevent the formation of appreciable amounts of deleterious by-products. As set forth in that application, excellent extreme pressure characteristics are imparted to the mineral lubricating oil by minor amounts of such sulphurized sperm oil, say 5 to per cent by weight on the mineral oil.

The lubricants so produced are stable in storage and are satisfactory as lubricants in lubricating metals both under ordinary and high pressures. As also set forth in. said application, amounts of such sulphurized sperm oil are also useful to render certain mineral lubricating oils non-corrosive of special alloy bearings; metal alloys, for instance, primary and ternary alloys of cadmium, silver, copper, lead and nickel, which would ordinarily be attacked by those mineral lubricating oils.

The motor oils and like lubricants containing a fraction of a per cent of sulphurized sperm oil as corrosion inhibitor, say 0.85 per cent, have a relatively longer life in service than the original motor oil. Being subjected-to the conditions of service for longer periods of time, the slud ging characteristics thereof become even more important. For instance, in the crank case of an auto mobile engine, sludging is the primary cause of their failure.

We have found that when the mineral lubricating oil is derived from a naphthenic base, this sludging is sufficient to require a change of lubricant while the main portion of the oil is still in good condition.

We have further found that traces of impurities in the sulphurized sperm oil also influence this sludging. In the sulphurized sperm oils prepared by the methods of application Serial No. 60,355, mentioned ante, these amounts of impurities in the sperm oils are so small that for ordinary purposes their presence is immaterial. However, when they and some constituents from the naphthenic base oil are present in a motor oil and that motor oil is subjected to high temperatures and other conditions conducive to sludging, apparently these traces of undesirable impurities from suchsources unite together in some way to give complexes increasing the sludging. With sulphurized sperm oils containing larger amounts of such impurities or by-products of the sulphu'rization, the sluding of the motor oil is greater in proportion. Using sulphurized fatty glycerides instead of sulphurized sperm oils, such lubricants similar conditions.

have relatively poor resistance tosludging under We have now discovered means whereby the sludging characteristics of such motor oils and lubricants may be so improved as to reduce the frequency at which thelubricant must be replenished or replaced with fresh lubricant. This is accomplished by refiningthese motor oils or lubricants in such a way as to remove the undesirable impurities without deleteriously affecting the other desirable properties of the lubricant. In fact, such refining as here employed improves certain other properties of the oil compositions containing sulphurized fatty esters, for instance their color and stability in storage. The present invention in refining such materials is broadly applicable to a wide variety of products and compositions.

By the present refining methods, unstable lubricating compositions which in storage percipitate certain impurities (derived from sulphurized fatty esters) may be rendered stable in storage and otherwise improved. Even sulphurized oil.

compositions which are generallystable under most of the ordinary conditions may be further stabilized. Some conditions of storage, such as those wherein the lubricant is exposed to light for long periods of time, have been found to cause precipitation of matter heretofore held in solution in the otherwise stable compositions. is particularly true when relatively small amounts of sulphurized fatty esters have been employed to improve the mineral oil. Apparently such materials are partially held in solution by the desirable components of such sulphurized oils or esters and are precipitated when the ratio of mineral oil to improvement agent is increased.

For instance, extreme pressure lubricants contalning a suiiicient amount of carefully sulphurized sperm oil to give marked extreme pressure characteristics to the mineral oil are relatively stable even when subjected to the action of light and stored for relatively long periods. On the other hand, certain lubricants for'the said alloy bearings, which contain a parafilnic lubricating oil and a relatively small amount of such sulphurized sperm oil, deposit traces of precipitated material when exposed to the action of light in storage for a relatively long period. This precipitation does not ordinarily occur inthe dark, that is when the 'oil composition is stored or packagedin metal cans or other closed containers impervious to light.

We have now found that the various impurities .and undesirable materials, mentioned ante, may

be removed from such compositions in a simple, advantageous manner. We have discovered that the acid-washed clays and other adsorption agents, ordinarily employed in the refining of mineral oil stocks, are also capable of adsorbing the said impurities present in oil compositions containing sulphurized fatty esters. In the present refining procedures, an acidwashed clay such as that known to the trade as Filtrol is ordinarily employed. In the present process the corrosive sulphur-containing by-products of the sulphurizing reactions are also absorbed and removed. Thus it is now possible, according to the present invention, to employ sulphurized fatty esters which heretofore were considered unsuitable in preparing commerciallubricants. By the present invention, mixtures of mineral oil and such corrosive sulphurized fatty'oils may be refined by the procedures given post and so im- ThiS proved thereby as to obtain compositions directwashed clay or other adsorbent agent, and the mixture agitated and warmed until the impurl ties have been adsorbed and fixed by such agents. Then the treated oil composition is separated from the treating agent. advantageously this separation may be effected by filter-pressing. The treating agents also absorb a portion of the oil composition and the absorbed oil composition may be recovered by washing or extracting the so-separated treating agent with liquids capable of dissolving the oil composition but which are non-solvents for the said impurities. Suitable volatile aliphatic oil solvents may be employed amounts of simple straight-chain aliphatic hydrocarbons, suchas the volatile mixture of hydrocarbons known as paraiilnic naphtha, are advantageous for this purpose. extract substantially all of the oil composition without disturbing the adsorbed impurities held by the clay. Also, the washed clay may be easily separated from such volatile solvents.

In the present treatment of the oil composition with clay or other adsorbing agent, the impurities, etc., being removed are of somewhat different character-than those present in the mineral oils which have heretofore been clay treated in refining. Therefore, the conditions employed are quite different from those used in the clay treatment of the usual mineral oil stocks. In the present methods, after the introduction of the clay, the mixture is heated to temperatures between 250 and 275 F. The temperature should be held below 300 F, At higher temperatures discoloration of the oil occurs and overheating offsets the improvement in color otherwise obtained by this treatment. During such heating the mixture should be thoroughly agitated, the agitation being continued until substantiallyall of the removable substances have been adsorbed. with most oil compositions and ordinary apparatus, about three hours is sufiicient to adsorb the amounts of undesirable impurities commonly present in these compositions. However, the

time of treatment more or less depends upon the particular material being processed and the other conditions. With the temperatures here employed, it is usually safe to continue the treatment .for from fifteen to thirty minutes after a test sample indicates that the refining is satisfactory. In this way an excess of treating agent can be stirred throughout the mixture to insure uniformity of refining. Ordinarily, an excess of treating agent is employed to insure complete adsorption of impurities, etc. Naturally, the amount of treating agent may be varied according to the particular oil composition being refined, the amount and character of the materials to be removed, the particular agent employed, etc. Generally a minor amount of treating agent by weight on the oil composition is employed. It is not convenient to use more than 50 per cent by weight of the treating agent in most cases, a

much smaller amount, say 1 to 30 percent, is

bility of the mixture to a point where agitation They effectively and subsequent separation or the oil composition from the adsorbed impurities is difficult. When the required amount of treating agent would render the oil composition thick or pasty upon admixing, the mixture may be thinned with sumcient mineral oil to secure the necessary mobility. In refining most 011 compositions sufiicient fluid oil is present to render this unnecessary. The details of the clay treatment may be easily adjusted to the refining of finished lubricating oils, such as the motor oils having extreme pressure characteristics or motor oils for lubricating alloy bearings, of intermediate mixtures of lubricating oil and sulphurized fatty esters, and of sulphurized fatty esters themselves, etc.

In these refining methods, we have also found that acid treatment prior to the clay treatment is advantageous, as in ordinary refining of mineral oils. Here again the difi'erent characters of the substances to be removed or obviated by this step of the refining process require changes in the procedure employed. We have discovered that acids, such as ordinary concentrated sulphurlc acid, for instance commercial acid known as black acid, are capable of precipitating, absorbing, and extracting the undesirable constituents mentioned ante.

Some of .the impurities are extracted; others are directly precipitated from theoil composition and the precipitated material adsorbed or colloidally suspended in the acid sludge obtained. Still other impurities and color producing materials react with or are decomposed by the acid and the resulting products are found in the acid sludge. A nother action in the acid treatment probably is a polymerization or agglomeration of some of the impurities; generally such materials find their way into the acid sludge. However, those which remain in the acid-treated oil are in such condition that they are readily removed by the subsequent clay treatment. Likewise, the acid sometimes forms a colloidal precipitate of other matter which remains colloidally dispersed in the oil. This, too, usually is easily removed'during the clay treatment.

However, in some special instances an extremely fine colloidal suspension of rather minute amounts of some impurities is found in the acidtreated oil; these are similar to the so-called peppery dispersions encountered in treating mineral oils; They may be due to somewhat similar causes. They, too, may be removed by a suitable modification of the present acid treat ments. In that modification the acid-treated oil after separation of the sludge is treated with less than 1 per cent, usually 0.25 per cent, by weight of water on the oil. The so-moistened oil is then air-blown to coagulate the pepper, a few minutes of air-blowing being usually sufficient. As soon as the colloidal material has agglomerated, the blowing is stopped and the oil so obtained is clay treated;

While the action of the acid, particularly sulphuric acid, is quite pronounced as to the said undesirable constituents, we have found that the simple'sulphur-addition products and other desirablecomponents of the sulphurized oil as well as the mineral oil constituents are not substantially attacked by the acid treatment. There is no serious loss of valuable material in the acid treatment. For instance, there is no appreciable nor serious change in the combined sulphur-content of the composition. Some of the acid-refined oil may be mechanically trapped in the acid sludge, but with proper processing this can be prevented or the oil recovered in a suitable manner. In this connection, we have made another important discovery. We have found that .the.

penetration of the oil composition by the acid is so effective that the Stratification of the sour oil from the acid sludge requires a special .adjustment of the procedure. In the present processes, the mixture during the acid treatment is heated to between 150 and 225 F. At those temperatures, with vigorous agitation of the mixture, a thorough acid-refining is efiected. Then, by discontinuing the agitation, a rather sharp stratification is obtained. Below 150 F. the stratification is not so sharp and appreciable amounts of refined oil may remain mechanically trapped in the acid sludge. At temperatures below 125 F., there is little or no Stratification. This solubility of the acid in the oil composition at such temperatures may be used to advantage in some modifications of the present process.

That is, the acid and oil composition may be mixed at low temperatures and then the mixture gradually brought to above 150 F., While being agitated, and maintained at such temperatures until the acid treatment is substantially complete. Then the stirring is discontinued and stratification effected within the desired temperature range mentioned above. Sometimes the mixture, after the stirring has been stopped and the stratification is occurring, may be held at 225 F. to form a hard, coke-like sludge which readily settles out of the sour oil. When such hard sludges are. formed, they may be separated by filtration or Stratification. After the sour oil and acid sludge have been separated in any of these ways, the acid sludge is then removed. When the acid sludge is in a liquid condition, this underlying layer may be simply withdrawn from the treating vessel. The sour oil remaining in the reaction vessel is then ready to clay treat.

In the above described acid treatment, the ratio of acid to the oil composition may be varied over a wide range. Ordinarily, concentrated sulphuric acid, containing 80 to 98 per cent H2804, is mployed, particularly in-refining lubricating compositions in which a large amount of mineral oil is present with small amounts of sulphurized fatty esters, These compositions require from 5 to 100 lb. of concentrated acid per barrel of oil composition (approximately 400 lb. of oil composition). Of course, the amount of acid employed depends on the amount of refining desired or required. When larger amounts of sulphurized fatty esters are present and the percentage of impurities contained in them is increased, the acid is proportionately increased. With highly colored materials, that is dark oil compositions, the amount of acid required is proportionately higher with respect to the amount of impurities present, as small amounts thereof will greatly affect the color. To insure complete decoloriza tion substantial excess of acid is employed. This desolorization by means of the acid treatment is one of the outstanding advantages thereof, in addition to the advantages secured by the combined acid and clay treatments mentioned ante.

In refining the finished high grade lubricants, mentioned ante, to further improve such compositions, ordinary clay treatment alone may be used. This is for the reason that the sulphurized sperm oils employed usually have a satisfactory color as does the lubricant obtained, and a slight additional improvement in their color is easily .obtained with the clay treatment alone. However, when darker colored sulphurized sperm oils, or sulphurized fatty glycerides are employed, a preliminary treatment with acid gives a marked improvement in the color of the compositions obtained after the subsequent clay treatment. When this is desired, it is advantageous to use the refining procedure at an intermediate stage in the manufacture of the lubricant. That is, the dark colored fatty esters are diluted with some mineral oil, say an equal amount of lubricating oil, and this intermediate composition refined by the present methods, using a combination acid and clay treatment; a further amount of mineral oil is subsequently added to the refined intermediate product to adjust the content of the sulphurized fatty ester to the desired concentration in the final lubricating oil or other lubricant. In such multi-stage methods, the mineral oil used may be the same or different at each stage. For instance, the diluent oil may be one derived from a naphthenic base and the final adjusting oil one of paraflinic base. The paraffinic oil may be used as the diluent and the naphthenic oil subsequently added.

Further, the sulphurized fatty esters may be directly refined. The mobile sulphurized sperm oils ordinarily have a relatively light color and they may 'be directly treated with clay. With the more viscous and darker sulphurized fatty esters, it is advantageous to refine them in a diluted condition in order that the amount of clay required can be easily separated after the impurities have been adsorbed. For this purpose diluents other than mineral oils may be employed. For instance, the same light parafiinic naphtha employed for washing the separated clay may be used for this purpose. Also, the so-diluted sulphurized fatty esters may be given a preliminary acid treatment. In such instances, the acid treatment of the sulphurized fatty ester diluted in the volatile solvent may be effected at lower temperatures, sometimes at room temperature; the change in diluent rendering this possible. However, a relatively larger amount of acid-treated oil remains in the acid sludge. The diluent being volatile, heating to high temperatures to harden the sludge cannot be employed. In refining the sulphurized fatty esters in the dilute state, a choice of solvents may be made, depending upon whether the removal of color-forming materials or loss of sulphurized fatty ester is more important.

The following examples are illustrative embodiments of the methods and. products broadly set forth ante, and are not limitative of the invention.

Example 1.This example illustrates the clay refining of an intermediate composition comprising a mixture of equal parts by weight of sulphurized sperm oil and mineral oil; the properties of the sulphurized sperm oil to be refined and of the diluent mineral oil being as follows:

sulphurized sperm oil (The above sulphurized sperm oil was prepared g 7 2,179,064 by a gradual sulphurization, according to the procedure of Example 1, of patent applicatio Serial No. 60,355.)

Mineral lulm'cating oil Gravity, "A. P. I. 33.1 Specific gravity, 60l60 F 0.8597 Viscosity, S. U. V., seconds:

100 F 180 10- 130 F 98 '210 F 4 46 Viscosity Index. 1 8 V-G consta t 0.800 Flash, 0. 0., F 420 Fire, 0. 0., F 490 Pour, F i 0 Color, N. P. A r 1.25 Sulphur, per cent 0.05 Carbon residue -1 0.02

(The above mineral oil is a highly refined motor oil derived from a paraflinic oil base.) 'Ihe parafilnic mineral oils, while they readily dissolve the sulphurized sperm oils, have a precipitating action upon many of the impurities present. Thus they are excellent diluents for the present purpose.

Into a suitable vessel equipped with agitating means, there is charged 2000 pounds (approximately 5 barrels) of the said mineral oil solution Refined intermediate oil composition Gravity, A; P. I 23.7

Specific gravity, /60 F 0.9117 Viscosity, S. U. V., seconds: a

50 V-G constant 0.848

Color, N. P. A v 6.5

Sulphur, 13, per cent 5.61

Carbon residue 0.35

The above refinedsolution of sulphurized sperm oil imparaflinic motor oil is an excellent intermediate for preparing a wide range of commercial lubricants. Typical illustration of their use in making lubricating compositions are iv p st- The above refined intermediate is stable to light. Even when further diluted with large amounts of highly paraffinic mineral oil, the oil compositions so obtained may be stored for long periods while exposed to light without any separation of insoluble matter. Such a dilute composiia'on is shown post in Example 3.

The filter cake, obtained in Example 1, containing some residual refined oil composition absorbed therein, may be treated to recover the oil by suitable means, such as washing with a paraflinic oil, for instance the same motor oil employed as 75 a diluent for the sulphurized sperm oil.

v In so washingthe filter cake, it is broken up and stirred into a relatively large volume of mineral oil, about 10 pounds of mineral oil to 10 pounds-of filter cake being usually sufiicient. The mineral oil solution of recovered sulphurized sperm oil, soobtained, may be used as a diluent for the present purposes in lieu of the mineral oil itself. Thus some of the mineral oil may be recycled in the present processes. But'little valuable oil is lost with the spent clay.

When such solutions are used, in lieu of the mineral oil itself for preparing intermediates for refining, it is advantageous to subject the dilute sulphurized sperm oil to a preliminary acid treatment prior to clay refining; In this way any soluble color-giving impurities extracted by the mineral oil and so introduced into the intermediate, can be readily removed or destroyed during the subsequent refining.

.As pointed out ante, other diluents may be employed in lieu of the parafiinic mineral oils. This is also true of mineral oils used for washing the filter cake. That is, mineral oils derived from naphthenic oil bases, such as those obtained by solvent extraction, etc., may be used for either of said purposes. When naphthenic oils are employed for either of these purposes the intermediate oil compositions ordinarily are also given an acid treatment prior to refining with clay. The following example is illustrative of the procedures employed in the acid refining operation of the present invention.

Example 2.--In this example an intermediate oil composition comprising a mixture of equal parts by weight of a sulfurized sperm oil (the same as inExample 1) and a mineral oil derived from a naphthenic base oil by solvent extraction is employed. The properties of such lubricating oil forming the solvent for the sulfurized oil are as follows: I

(The above mineral oil is a S. A. E. 10 grade motor oil obtained by solvent extraction from mixed base stocks.)

Into a suitable vessel equipped with agitating means there is charged 2000 pounds (approximately 5 barrels) of the said mineral oil solution of the sulphurized sperm oil. The solution is agitated and heated to slightly above 150 F. While continuing the agitation, pounds of 98 per cent commercial sulphuric acidis added, and the mixture heated to approximately 200 F. About 30 minutes is required to bring the mixture to sharp Stratification and complete the acid refining. At that time the agitation is discontinued and most of the acid sludge is permitted to settle out, the mixture being held at or raised to slightly above 200 F. during this time. About 15 minutes at such temperatures converts most of the settled sludge and all of the residual sludge remaining in the oil into a hardened solid material. The sour oil is withdrawn from the settled sludge and pumped through a suitable filter 'press.

Any residual sludge remaining suspended in the sour oil is thus effectively removed. The sour oil obtained by this filtration is next processed and further refined by treatment with clay.

In the clay refining the sour oil obtained as above, by the procedure given in Example 1, is employed. The sour oil having been filtered hot, the filtrate obtained is only slightly below 200 F. in temperature so that slight further heating is necessary to bring it to the higher temperatures advantageous in clay refining, say to about 275 F., as employed in the procedure of Example 1.

Also the intermediate oil composition, given ante, may be efiectively refined byciay treatment alone when extremely light color is not required. By clay refining as given in Example 1, an improved intermediate composition having the fol- The above intermediate oil composition was comprised of a sperm oil sulphurized by the method of patent application Serial No. 60,355, and an equal amount of solvent refined S. A. E. 10 grade mineral lubricating oil, the properties of which were:

Mineral Sperm lubrioil. eating oil Gravity, at. P. I. 13. 2 2e. 6 Specific gravity, 60/60F 0. 9779 0. 8833 Viscosity S. U. sec

100 131..-- 2012 1 210 265 .44. gum o C F 30 no 50 you +60 Color, N. P. A Dark 2. Sulphur, B. per cent. 11.0 0. 13 Carbon mu... 0.02

The above examples illustrate the present refining methods as employed in the manufacture of lubricants; an intermediate oil composition being refined prior to making the final lubricate ing composition. However, as stated ante in this specification, the refining methods are per se useful in refining finished lubricants. The following example'illustrates the refining of a motor 011 containing a relatively small amount of sulphurized sperm oil obtained by gradual sulphurization of a commercial sperm oil; the amount of sulphurized sperm oil being sufiicient to render such mineral oils non-corrosive of the special alloy bearings mentioned ante in this specification.'

' Emmple m In'this example a motor oil (one suitable forlubricating ,the said alloy bearings) I v comprising a one per cent solution of sulphurized sperm oil in a parafiinic motor oil, is refined by ajsimple claytreatinent. The sulphurized sperm' oil and the mineral oil of this motor oil composition individually have the following properties:

sulphurized sperm oil obtained by gradual sulphurization Paraflinic motor oil Highly refined oil from Pennsylvania stock Gravity, A. P. I 33.0 Specific gravity, 60/60 F 0.8602 Viscosity, S. U. V., seconds:

100 F 182 130 F 99 210 F 46.5 Flash, 0. 0., F 420 Fire, 0'. 0., F 490 Pour, "F Y 0 Color, N. P. A 1.25 Sulphur, B, per cent 0.05 Carbon residue The above mentioned motor oil is heated to 275 F., and acid-washed clay is gradually added with stirring; 20 per cent of clay by weight on the sulphurized oil content of the motor 011 being used, that is 0.8 pounds of clay per barrel of this motor oil is sufficient. So refining the motor oil composition is to further improve it to obtain a superior type of lubricant.

After the clay has been added, the mixture is agitated at the said temperature for about one hour. The improved motor oil is then recovered by filter pressing.

Despite the simplicity of the above refining a marked improvement is obtained in the motor oil. This is clearly shown by the properties of the motor oil before and after refining as given in the following table:

Oil composition Before Alter refining refining Gravity, A. P. L 32. 7 32.8 Viscosity, S. U. V., seconds:

100 F 189 187 130F 102 100 210 46. 8 46. 5 Flash, 0. C 420 420 Fire, 0. C F 490 490 our, "F 5 5 Color, N. P. A 3.75 1. 5o Sulphur, 13,, per cent 0.17 0. 14 Carbon residue, per cent 0. 02 0.01

By the procedure of the above examples other motor oils containing small amounts of sulphurtained at this temperature while being 5 for 16 hours. The heating is thereafter stopped and the sulphurized oil cooled to room temperature, The total time from the first addition of sulphur to the completion of the reaction is about 18 hours.

20 The sulphurized lard oil 'so obtained following properties:

Gravity, A. P. I; 10.1 Specific gravity, 60/60 F 0.9993

has the Pounds per gallon 8.322 Viscosity, s. U. v. at 210 n, seconds-.. 337 Pour, F +65 Sulphur, B, per cent 10.0 Color, N. P. A Dark The sulphurized lard oil so obtained is dissolved in sufiicient mineral'oil to produce a 50 per cent solution of the sulphurized lard oil. In preparing such solutions it is advantageous to use -a highly paraflinic lubricating oiLfor instance the highly refined lubricating oil set forth in Example 1.' Such parafiinic mineral oils have a precipitating action upon certain deleterious by-products contained in thesulphurized fatty glycerides.

40 The mineral oil solutions ofsulphurized lard oil or other fatty glycerides maybe advantageously refined with clay, either with or without preliminary acid treatment.

The solution of sulphurized lard oil is admixed 45 with 20 per cent by weight of acid-washed clay I on the oil composition. The'mixture is agitated at 275 F. for three hours. The heated mixture is then filter pressed to recover the refined oil composition.- The oil solution so obtained has 50 the following properties:

Gravity, A. P. I 22.5 Viscosity, S. U. V. at 210 F., seconds 87 Flash, 0. C., F 410 Fire, 0. 0., F 480 55 Sulphur, B,'per cent 5.1 Color, N. P. A 5.5

The refined oil composition is a useful intermediate for making various lubricants. In mak-' 60 ing lubricants, it is usually blended with more mineral oil to produce compositions containing the desired percentages of sulphurized fatty oil.

Example 5.Into a grease kettle, as employed in Example 4, there is charged a similar amount 70 required.

I The sulphurized lard oil so obtained is again dissolved inmineral oil to obtain a mineral oil composition adapted to the present refining methods. This oil solution of' the sulphurized 75 lard oil may be prepared as in Example 1. It

also maybe prepared by other suitable methods.

Prior to the dilution with mineral oil, the sulphurized lard oil has the following properties:

The viscosity and certain other properties are somewhat variable as the composition contains.

considerable amounts of by-products dissolved in the desirable components of the sulphurized oil. This sulphurized mixture may be directly refined by the present refining methods; however, as stated ante, it is advantageous to first dissolve the sulphurized oil in mineral oil and then refine the oil compositions so obtained.

The above sulphurized lard oil is dissolved in an equal weight of the mineraloil employed in Example 1. The mineral oil solution of sulphurized lard oil is refined with clay as in Example 4. Thus there is obtained a valuable intermediate-oil composition having the following properties:

Gravity, A. P. I 23.1 Viscosity, S. U. V. at 210 F., seconds 73 Flash, 0. (2., F 420 Fire, 0. 0., F 490 Sulphur, B, per cent 4.9 Color, N. P. A 8.0

The above intermediate oil composition may be employed to prepare lubricants in the same manner asthe refined oil composition obtained in Example 4. Either lubricating oil derived from a parafiinic stock or from a naphthenic stock or a mixed base .may be employed in making the finished lubricant.

In the refining methods of Examples 4 and 5, the solution of sulphurized lard oil may be preliminarily refined by an acid treatment according to the procedure of Example 2, prior to the said clay treatment.

In lieu of sulphurized lard oil, other sulphurized fatty glycerides or oils maybe likewise refined, such as those obtained from vegetable oils, fish oils, etc.

Also, sulphurized fatty mono-esters other than those obtained from commercial sperm oil may be refined by the present invention. The sulphurized fatty mono-esters obtained by the methods described in co-pending application Serial No. 60,357, and mineral oil solutions of such mono-esters may be improved by the refin-, ing methods of the present invention. As shown in that application, the sulphurized mono-esters obtained by reacting sulphur with an unsaturated mono-ester having the following formula wherein R represents an aliphatic group, at least one of said aliphatic groups being unsaturated prior to sulphurization, are advantageous as improvement agents for mineral oil lubricants; the sulphurized mono-esters being substantially neutral organic sulphur compounds readily soluble in mineral oils. By the present invention, lubricants containing such sulphurized monoesters can be further improved when refined as herein described. As stated ante, these refining methods are generally applicable to lubricants containing sulphurized fatty esters.

By our refining methods given ante, oil compositions containing from 0.5 to 60.0 per cent of sulphurized fatty esters may-be treated and improved as illustrated in the above examples. The improved oil compositions are stable to light and have improved resistance to sludging. While commercial lubricants may be directly improved by these refining methods, it is advantageous to efiect the refining in an intermediate stage of manufacture as shown ante. In this way, the refined intermediate can be'blended with the desired amount and type of additional mineral oil to obtain a rather exact adjustment of the properties of the final lubricating composition.

Lubricants containing a mixed blend of mineral oils may be readily prepared in this way.

By the present invention, refined intermediates containing from 5 to 15 per cent of sulphurized sperm oil or other fatty esters may be prepared and a minor amount of a difierent mineral oil added to them in preparing the final lubricant. That is, in reducing the percentage of sulphurized sperm oil to that desired in the final composition, a mineral oil different from that employed in making the intermediate oil composition for refining may be employed. In this way,'lubricants containing mixed mineral oils as the lubricating base are advantageously prepared. Thus a minor amount of a' paraflinic oil may be employed in adjusting the properties of a solution of sulphurized sperm oil in a majoramount of a lubricating oil derived from a naphthenic base, such as by solvent extraction. In like manner, paraffinic mineral oil solutions of sulphurized esters (refined intermediate) may be adjusted by adding oil derived from a naphthenic stock.

Lubricants containing a major amount of one type of mineral oil and a minor amount of another type mineral oil, in addition to the sulphurized esters, are advantageous for certain purposes. In such compositions, the percentage of sulphurized esters may be rather low, say from 0.5 to 2.0 per cent, and their lubricating properties excellent for lubricating certain bearings under drastic service conditions.

What we claim is:

1. As an improvement in making motor oils and lubricants containing sulphurized fatty esters, the method of refining a mineral oil composition containing said sulphurized fatty esters to remove the deleterious non-volatile materials associated with the sulphurized esters, which comprises contacting the oil composition with suflicient acid washed clay to absorb said deleterious materials maintaining the 011 composition in contact with the clay until the clay absorbs the deleterious material and then separating the oil composition from the clay and absorbed impurities.

2. The process of claim 1 wherein the oil composition prior to the clay refining, is admixed with sulphuric acid and the acid treated oil is separated from the acid sludge, the sour oil so obtained being then clay refined to remove the remainder of said deleterious materials.

3. As amethod of refining oil compositions containing sulphurized sperm oil, the process which comprises admixing a solution of sulphurized sperm oil in mineral oil with an acidwashed clay, agitating the mixture until said clay absorbs the materials deleterious in lubricating compositions and then separating the refined oil composition from the clay and absorbed impurities.

4. The process of claim 3 wherein the oil composition contains between 0.5 and 60.0 per cent of sulphurized sperm oil.

5. The process of claim 3 wherein the mixture 4 of the said clayand oil is agitated at temperatures between 250 and 275 F., until the said impurities are adsorbed by the clay and the mixture is filter pressed to recover the improved oil composition.

6. The process of claim 3 wherein the oil composition prior to the clay refining, is admixed with sulphuric acid, the mixture is heated until an acid sludge is formed and the sour oil is separated from the acid sludge. I

7. The process of claim 3 wherein the sulphurized sperm oil is obtained by gradual controlled sulphurization and contains a trace of impurities precipitable from mineral oil solutions by the action of light.

8. In improving mineral oil lubricants containing minor amounts of sulphurized fatty esters, the refining method which comprises heating the mineral oil composition with sulphuric acid, separating and removing the acid sludge, mixing the recovered sour oil with acid-washed clay, heating the mixture to between 250 and 275 F., and separating the refined oil composition by filter pressing the hot mixture.

9. The process of claim 8 wherein the oil composition is mixed with acid and the mixture heated to between and 225 F., the acid sludge is removed by settling, and the sour oil is filter pressed.

10. The process of claim 8 wherein the said sulphurized fatty ester is a mono-ester.

11. The process of claim 8 wherein the said sulphurized fatty ester is a glyceride.

12. The process of claim 8 wherein said oil composition contains between 5 and 20 per cent of sulphurized ester and the refined oil composition is subsequently diluted with additional mineral oil to adjust the content of sulphurized ester in the finished improved lubricant.

13. The process of claim 8 wherein the oil composition contains about one per cent of sulphurized sperm oil.-

14. The process of claim 1 wherein said sulphurized fatty ester is sulphurized sperm oil.

15. The process of claim 1. wherein said sulphurized fatty ester is a sulphurized mono-ester obtainable by reacting sulphur with an unsaturated mono-ester having the following formula:'

wherein R represents an aliphatic group, at least one of said aliphatic groups being unsaturated prior to sulphurization.

16. The process of claim 1 wherein said sulphurized fatty ester is a glyceride. 4

17. The process of claim 1 wherein said sulphurized fatty ester is sulphurized lard oil.

HERSCHEL G. SMITH. TROY LEE CANTRELL.