US2560548A

US2560548A - Method of processing solvent-ex

Info

Publication number: US2560548A
Authority: US
Publication date: 1951-07-17
Anticipated expiration: 1968-07-17

Description

Patented July 17, 1951 METHOD OF PROCESSING Es PATENT OFFICE SOLVENT-EX- TRACTED LUBRICATING OIL BY TREAT- ING WITH A PHOSPHORUS SULFIDE, A BASE AND- CLAY- AND THE RESULTING PRODUCTS .lohn D. Bartleson, East Cleveland, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application May 29, 1948, Serial No. 30,208

14 Claims. (Cl. 25232.7)

This invention relates to processes of improving hydrocarbon base lubricants, and more particularly to subjecting hydrocarbon lubricant stocks tosolvent refining, then treatment with a small amount of a phosphorus sulfide and fo1- lowing this by the treatment thereof with a base, especially a metal base. A clay treatment may be included before or after the treatment with the base. The resulting refined lubricants have improved properties, especially as to corrosion, lacquer, sludge, viscosity increase, and the like characteristics. It also relates to the resulting improved lubricants, especially those having an ash content.

Many of the commercially used lubricants are based upon hydrocarbon stock, which may be synthetically prepared or which may be derived from natural sources, such as petroleum. For many purposes so-called additives must be in cluded with the hydrocarbon in order to provide a lubricant having suitable characteristics. This is especially so in the case of solvent refined oils which are known to be corrosive, and in cases where detergency is a wanted property. Generally the inclusion of these additives is associated with a higher cost of the finished lubricant. The preparation of a finished lubricant directly from hydrocarbon stock by a chemical finishing or refining process at a commercially interesting cost has been a difficult problem in the art.

In accordance with the invention, it has been found that hydrocarbon lubricating oil stock may be solvent extracted with sulfur dioxide, furfural, phenol, or the like in the conventional modern manner, and then reacted with a small amount of a phosphorus sulfide, and following this, with a base; a clay treatment is included before or after the treatment with the base, and the resulting reaction product is an improved lubricant; i. e., a chemically finished or refined lubricant. Such lubricants are suitable for use under various conditions, including high temperatures or highpressures or both; as, for'instance, use in an internal combustion engine operating at high am peratures and in which the lubricant is inclose contact with metallic surfaces, metal compounds and high temperature gases. They are also suit-' able for use in extreme pressure lubricants, e. g'., in oils and greases containing them. p

The treatment of the hydrocarbon oil with the solvent may be carried out in the conventional modern manner. The solvent tends tov extract aromatic unsaturated and low viscosity index constituents; and these are separated from the oil. This step is well known in the art and need not be further described here.

The resulting hydrocarbon oil is then refined with a phosphorus sulfide which may be conducted with direct admixture, or, if desired, by their admixture in the presence of a diluent which may be subsequently removed. Generally a diluent is not necessary. The sulfide treating step is usually complete in about 10 hours or less time, generally 1 to 2 hours. The treating time is a function of the temperature, the amount of sulfide that is to react, the subdivision of the reactants, the efficiency of mixing thereactants, and the like. The solventrefined hydrocarbon lubricant stock is reacted with a phosphorus sulfide in a ratio of from about 0.1 to about 0.75% by weight, based on the weight of the hydrocarbon stock, desirably about 0.25 to about 0.65%. f

The treatment of the solvent-refined hydroe carbon with the phosphorus sulfide may ';be carried out'in the presence or absenceof air, or in an atmosphere of inert or non-deleterious gas, such as nitrogen or HzS. It may also be carried out under pressure, e. g., pressure of the inert gas or that generated when the reaction is carried out in a closed vessel. The sulfide treating temperature varies with the hydrocarbon lubricating stock. Generally the temperature should be at least 2'75F., but should be below the temperature at which the reaction product would be decomposed. A temperature in the range of about 300 to about 450 F. is preferred in many cases. The treated oil (e. g., after conversion to a base derivative) is preferably centrifuged or filtered to remove any by-products, sludge, or other by-product material. If a volatile diluent is used, it maybe removed by evaporation. The solvent and sulfide refined oil is then treated with a base derivative, such as a metal compound. The metal base may be one or more metal compounds, such as their sulfides, oxides, hydroxides, carbides and cyanamides' The preferred metals are group I, group II and group III metals of the periodic table, such as potas sium, zinc, barium and aluminum. For particular services, the heavier metals have particular use, i. e., those below zinc in the electro-' motive series, such as chromium, cadmium, tin,

From about 0.25'to about 6.0 equivalents of the metal compound may be used per mol of the sulfide used in the sulfide treatment, preferably about 1.0 to about 3.0 equivalents. An equivalent is the quotient of a mol divided by the valence of the metal concerned.

The clay treatment may be carried out after the sulfide refining step or after the base conversion step or both. It is accomplished by mixing clay with the oil at a temperature of 32 to 300 F. followed by filtration. Any amount up to about ten pounds of clay per barrel of oil may be used.

The hydrocarbon lubricant stock to which the process is applied may be a raw oil, e. g., a fluid hydrocarbon having a viscosity at 100 F. of 10 to 500 centistrokes such as that used as the base in S. A. E. 10 to 50 oils. It may be obtained as a distillate or from synthetic material, such as petroleum, and oils produced by cracking, polymerization, hydrogenation, and the like methods.

The solvent refining process is well-known, and generally involves a physical separation. Usually, the solvent selected, such as furfural, phenol, sulfur dioxide, etc., dissolves such constituents as aromatic, unsaturated, and low viscosity index materials, and these are separated out. A clay treatment may or may not follow and is desirable but not essential. Where necessary, a separate propane or the like deasphalting treatment may be used in connection with the solvent refining.

In order to illustrate and point out some of the advantages of the invention, but in no sense as a limitation thereof, the following specific embodiments are included.

In these examples the hydrocarbon oil treated is a conventionally solvent-extracted clay-contacted lubricating oil, i. e., it has been treated in accordance with the first step of the process. The phosphorus pentasulfide is mixed with the solvent refined hydrocarbon oil, in the amounts indicated in the following table, and agitated for 1 hour at 300 F., at atmospheric pressure. Then it is mixed with the amount and kind of base (based on the weight of the hydrocarbon stock) indicated in the following table, and agitated for 2 hours at 250 F., at atmospheric pressure. The base is used in dry form in these examples; except in Example 6, wherein the base is used in the form of a saturated aqueous solution. In some of the examples a clay treatment is used between the phosphorus sulfide treating step and the base treating step; in others a clay treatment follows the base treating step. A good yield is obtained, based on the hydrocarbon lubricating oil stock, and no sludge is formed; however, it is preferred to filter the final reaction product. The reaction product is identified hereinafter by the example number.

Amount of Amount of Amount of P15 in Per Clay in fig fl fig Clay in Example Cent by Lbs. per in i, nt Lbs. per Number Wfiiggrt of BHarr;l of g g of y gauge] of y oy roy tocarbon carbon oil Hydrocarbon carbon oil 0. 4 0.4% KOH 0. 4 do 2 0. 4 5 O. 4 0 0. 4 0. 4 0. 4 O. 6

Sohio corrosion test was used in evaluating lubricants made in accordance with the invention. This test is described in a co-pending application of E. C. Hughes, J. D. Bartleson, M. L. Sunday and M. M. Fink, which also correlates the results of the laboratory tests with a Chevrolet engine test.

Essentially the laboratory test equipment consists of a vertical thermostatically heated glass test tube (45 mm. outside diameter and 42 cm. long), into which is placed the corrosion test unit. An air inlet is provided for admitting air into the low end of the corrosion unit in such a way that in rising the air will cause the oil and suspended material therein to circulate into the corrosion unit. The test tube is filled with an amount of the oil to be tested which is at least sufiicient to submerge the metals being tested.

The corrosion test unit essentially consists in a circular relatively fine grained copper-lead test piece of -l%" O. D., which has a diameter hole in its center (i. e., shaped like an ordinary washer). The test piece has an exposed copperlead surface of 3.00 sq. cm. Of this surface area, 1.85 sq. cm. acts as a loaded bearing, and is contacted by a part of the cylindrical surface of a hardened steel drill rod (14" diameter and 3% long, and of 51-57 Rockwell hardness).

The drill rod is held in a special holder, and the holder is rotated so that the surface of the drill rod which contacts the bearing sweeps the bearing surface (the drill rod is not rotated on its contacts the bearing is not changed).

The corrosion test unit means for holding the bearing and the drill rod is a steel tubing (15" long and 13 5" O. D.) which is attached to a support. A steel cup (1" long, 13 g" 0. D. by {-3 I. D.) is threaded into the steel tube, at the lower end. The cup has a diameter hole in the bottom for admitting the oil into the corrosion chamber. The copper-lead test piece fits snugly into the steel cup and the hole in the test piece fits over the hole in the steel cup. A section of steel rod in diameter and 19" long) serves as a shaft and is positioned by 2 bearingswlqich are fixedly set in the outer steel tubing, one near the top and one near the lower (threaded) endthere of. Several holes are drilled just above and just below the lower bearing. The holes above the bearing facilitate cleaning the apparatus, while the holes below the bearing enable the circulation of oil through the corrosion chamber. The drill rod holder is connected to the shaft by a selfaligning yoke and pin coupling. This assures instantaneous and continuous alignment of the drill rod bearing member against the bearingsur face at all times. A pulley is fitted to the top of the steel shaft and the shaft is connected therethrough to a power source. The shaft is rotated at about 675 R. P. M.; and the weight of the shaft and attached members is about 600 grams, which is the gravitational force which represents the thrust on the bearing. The air lift from the air inlet pumps theoil through the chamber containing the test piece and out through the holes in the steel tubing. 7

The ratios of surface active metals to' the volume of oil in an internal combustion test engine are nearly quantitatively duplicated in the test equipment. The temperature used is approximately that of the bearing surface. The rate of air flow per volume of oil is adjusted to the same as the average for a test engine in operation. Of the catalytic effects, those dueto soluble ,iror

are themost important. They are empirically duplicated by the addition of a soluble iron salti Those due to lead-bromide are duplicated by its addition. 1

The test was correlated with the 11-4 Chevrolet test, and a slightly modified version thereof. The

modified test comprised reducing the oil additions from the 4 quarts in the usual procedure to 2 quarts, by reducing the usual 1 pint oil additions which are made at l hour intervals at pint additions. This modification increases the severity of the test in its corrosion and detergency components, particularly in the case of border line oils.

For each test, the glass parts are cleaned by the usual chromic acid method, rinsed and dried. The metal parts are washedwith chloroform and carbon disulfide and polished-with No. 925 emery cloth or steel wool. A new copper-lead test piece is used for every test. The test piece is polished before use, on a surface grinder to give it a smooth finish. The test piece is weighed before and after the test on an analytical balance to evaluate the corrosion. After placing the oil and corrosion test unit in the tube, and bringing the assembly up to temperature in the thermostat, soluble cata lyst is added and the air flow is started. Leadbromide catalyst is added immediately after starting the air, and timing of the test is begun.

The laboratory test conditions which were found to correlate with the Chevrolet procedure 36-hour test are shown in the following table.

Table A Temperature-325 F. Oil sample107 cc. Air flow rate70 liters/ hour Time-l0 hours CatalystsSteel; copper-lead bearing: 3 sq. cm. area of which 1185 sq. cm. is a bearing surface; ferric 2-ethyl hexoate: 0.05% as FezOs in C. P. benzene; lead bromide:0.l% as precipitated powder. Bearing assembly:

Load "grams" 600 Speed R.P.l\/I 675 By extending the laboratory test to 20 hours, it was found that correlation with the Chevrolet '72- hour test could be obtained.

At the close of the test period, the extent of corrosionis determined by revveighing the corrosion test piece and determining the change in weight due to the test. An accurate evaluation of the lacquering properties of an oil is obtained by a visual rating system which is applied to the outer surface of the corrosion unit steel tube and metal cup in much the same way that the piston skirt, cylinder wall, etc. of an engine are rated for varnishes. The sludge rating of the engine is simulated by a visual rating of the insoluble materials and used oil which are coated on the glass test tube at the conclusion of the test. For both sludge and varnish rating a scale rating of A (best) to F (worst) is used.

A sufficient volume of used oil is obtained from the test for determination of the usual used oil properties, such as pentane insolubles (sludge), viscosity increase, neutralization number and optical density.

The data in the following tables typify the results obained in 20-hour Sohio corrosion tests on the hydrocarbon lubricating oil base stock, and the improved lubricants prepared therefrom in accordance with the invention.

Table I 7 LubricanF-Ekample No. 1 2 3 4 Corrosion of Cu-Pb (in mgms.

wt. lossof) 40. l 14. 4 ll. 0 18. 8 27. 5 Viscosity Increase (SUS) 4-, 070 148 328 Pentane Insolubles (in mgm./

10 g. of lubricant) ll. 3 14. 6 4.2 20. 8 112. 9 Acid Number 25. 8 2. 7 1.8 2. 2 3. 9 Sludge Rating..- A A+ A+ A+ A+. Lacquer Rating A 13+ A B B+' Table II Lubricant-Example N o. 5 6 7 8 Corrosion of Ou-Pb (in mgms.

S5 of) 40.1 29; 1 25. 9 18.8 1.0 Viscosity Increase (SUS). 4, 070 244 288 34 Pentane Insolubles (in mgm./

10 g. of lubricant) 11.3 81. 6 72. 9 123. 2 12.3 Acid Number. 25. 8 1. 9 3.1 4. 0 1.1 Sludge Rating. A A+ A+ A+ A Lacquer Rating A A A B+ 0 The conventional solvent refining treatment improves many characteristics of the lubricating oil, but generally gives a product having a poor corrosion characteristic, as indicated by the very high acid number. The above data clearly show that the phosphorus sufide and base treatments of the solvent refined oil give a superior lubricant. The very great improvement in viscosity increase of the lubricant of Example 2, as compared to to the blank, is noteworthy. The Example 8 product shows particularly desirable corrosion, viscosity increase, and acid number characteristics.

General in the clay treatment, from about 2 to about 10 lbs. of clay should be used per barrel. If large amounts are used, as shown in Example 4, especially after the base treatment step, the resulting product tends to be less desirable than where amounts in this range are used, especially as to corrosion and pentane insoluble. That an after clay treatment is beneficial is shown by a comparison of Examples 1 and 2.

In general phosphorus pentasulfide is most desirable and most economical; especially since its use in the process imparts to the lubricant an ash content. Other sulfides may be used, however, e. g., P483, with some success.

By comparable procedures, using any known comparable phosphorus sulfide, or amount of phosphorus sulfide, or hydrocarbon lubricating oil stock, within the broad types and ranges as indicated hereinbefore, comparable improved lubricants are obtained.

If desired, the improved lubricants of the invention may be used in blends together with other lubricants or lubricant agents, e. g., with soap or the like in a grease. If desired, an agent for improving the clarity of the oil may be included, e. g., lecithin, lauryl alcohol, and the like. If desired, an agent for preventing foaming may be included, e. g., tetra amyl silicate, an alkyl orthocarbonate, ortho formate or ortho-acetate, or a polyalkyl silicone oil.

In view of the foregoing disclosure, variations and modifications of the invention will be apparent to those skilled in the art, and it is intended to claim such variations and modifications broad ly, except as do not come within the scope of the appended claims.

I claim:

1. A method of further processing solvent-extracted lubricating oil stock consisting essentially of hydrocarbon material to yield an oil having improved inhibition to oxidation in service, which method comprises treating said stock with an amount of a phosphorus sulfide in the range of about 0.1 to about 0.75% by weight at a temperature in the range of about 275 to 450- F., then with an amount of a base in the range of about 0.25 to 6.0 equivalents per mol of the phosphorus sulfide, and including at least one separate clay treatment subsequent to the sulfide treatment.

2. The method of claim 1 wherein the phosphorus sulfide is phosphorus pentasulfide and the base is a metal base.

3. The method of claim 2 wherein the temperature is in the range of about 300 to 450 F., and the base is potassium hydroxide.

4. The method of claim 2 wherein the clay treatment is just prior to the base treatment.

,5. The method of claim 4 wherein the temperature is in the range of about 300 to 450 F., and an amount of potassium hydroxide in the range of about 0.2 to about 0.8% is used as the base.

6. The method of claim .2 wherein the clay treatment is subsequent to the base treatment. 2

7. The method of claim 6 wherein the temperature is in the range of about 300 to 450 F., and an amount of potassium hydroxide in the range of about 0.2 to about 0.8% is used as the base.

8. A lubricant obtained by the process of claim 1.

9. A lubricant obtained by the process of claim 2.

10. A lubricant obtained by the process of claim 3.

11. A lubricant obtained by the process of claim 4.

12. A lubricant obtained by the process of I claim 5.

13. A lubricant obtained by the process of claim 6.

14. A lubricant obtained by the process of claim 7.

JOHN D. BAR'I'LESON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,316,091 White Apr. 6, 1943 2,393,335 Musselman Jan. 22, 1946 2,398,429 Hughes Apr. 16, 1946 2,419,584 Noland Apr. 29, 1947 Certificate of Correction Patent No. 2,560,548 July 17, 1951 JOHN D. BARTLESON It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 7 4, strike out further and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oflice. Signed and sealed this 13th day of November, A. D. 1951.

THOMAS F. MURPHY,

Assistant Gommz'ssz'oner of Patents.

Claims

1. A METHOD OF FURTHER PROCESSING SOLVENT-EXTRACTED LUBRICATING OIL STOCK CONSISTING ESSENTIALLY OF HYDROCARBON MATERIAL TO YIELD AN OIL HAVING IMPROVED INHIBITION TO OXIDATION IN SERVICE, WHICH METHOD COMPRISES TREATING SAID STOCK WITH AN AMOUNT OF A PHOSPHORUS SULFIDE IN THE RANGE OF ABOUT 0.1 TO ABOUT 0.75% BY WEIGHT AT A TEMPERATURE IN THE RANGE OF ABOUT 275* TO 450* F., THEN WITH AN AMOUNT OF A BASE IN THE RANGE OF ABOUT 0.25 TO 6.0 EQUIVALENTS PER MOL OF THE PHOSPHORUS SULFIDE, AND INCLUDING AT LEAST ONE SEPARATE CLAY TREATING SUBSEQUENT TO THE SULFIDE TREATMENT.