US2560544A

US2560544A - Method of processing lubricating

Info

Publication number: US2560544A
Authority: US
Publication date: 1951-07-17
Anticipated expiration: 1968-07-17

Description

Patented July 17, 1951 METHOD OF PROCESSING LUBRICATING OIL BY TREATING WITH SULFURIC ACID, A PHOSPHORUS SULFIDE AND CLAY, AND THE RESULTING PRODUCT John 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. 30,204

Claims. i

This invention relates to processes of improving hydrocarbon base lubricants, and more particularly to the treatment of hydrocarbon lubricants with sulfuric acid followed by the treatment thereof with a small amount of a phosphorus sulfide, to form lubricants having improved properties, especially as to corrosion, lacquer, sludge, viscosity increase, and the like characteristics. It also relates to the resulting improved lubricants.

Many of the commercially used lubricants are based upon hydrocarbon stocks, which may be synthetically prepared or which may be derived from natural sources, such as petroleum. For many purposes so-called additives must be included with the hydrocarbon in order to provide a lubricant having suitable characteristics. This is especially so in the case of acid refined stocks. Generally the inclusion of such 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 (which does not involve solvent extraction) at a commercially interesting cost has been a particularly baiiling problem to the art.

In accordance with the invention, it has been found that hydrocarbon, lubricating oil stock may be refined by treatment with sulfuric acid in the conventional manner, and then may be further refined with a small amount of a phosphorus sulfide, and the resulting refined product is an improved lubricant; i. e., a chemically finished or refined lubricant. A clay treatment is included before or after the sulfide refining. Such lubricants are suitable for use under various conditions, including high temperatures or high pressures or both; as, for instance, use in an internal combustion engine operating at high temperatures and in which the lubricant is in close contact with metallic surfaces, metal compounds and high temperature gases. They are also suitable for use in extreme pressure lubricants, e. g., in oils and greases containing the same.

Treatment of the hydrocarbon oil with sulfuric acid may be carried on in the conventional manner, e. g., using from 1 to 100 lbs. of the acid per barrel of oil, at a treating temperature in the range of 32 F. to 300 F. A sludge or acid layer is removed. This step is long and well-known in the art. The resulting hydrocarbon oil is treated with the phosphorus sulfide. This 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 reaction or treating time is usually complete in about 10 hours or less time, generally 1 to 2 hours. The

time is a function of the temperature, the amount of sulfide that is to react, the subdivision of the reactants, the efiiciency of mixing the reactants, and the like.

The hydrocarbon lubricant stock is reacted with the phosphorus pentasulfide in a ratio of from about 0.1 to about 0.75% by weight, based on the weight of the hydrocarbon stock, and preferably about 0.25 to 0.6%. If a higher amount of the sulfide is used,.such as 1%, some of the characteristics of the resulting product are worse than the initial hydrocarbon oil, especially the viscosity increase. At least about 0.1% of the sulfide should be used to achieve the results desired on a commercial scale, although small amounts show improvement.

The treatment of the hydrocarbon with the phosphorus sulfide may be carried out in the presence or absence of air, or in an atmosphere of inert or non-deleterious gas, such as nitrogen or Has. It may also be carried out under pressure, e. g., pressure from the inert gas or that generated when the reaction is carried out in a closed vessel.

The sulfide treating temperature varies withv the hydrocarbon stock. Generally the temperature should be at'least 275 F., 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 finally treated oil is preferably centrifuged or filtered to remove any by-products, sludge, or other by-product material. If a volatile diluent is used, it may be removed by evaporation.

The stock is clay treated before or after the sulfide refining, i. e., after the acid treatment, or after the P285 treatment, or both. Treatment after the PzSs refining is preferred if only one clay treatment is given. The amount of clay is not critical. Any amount gives some improvement and the effect levels off with large amounts. Generally the amount will be 2 to 25 lbs. per barrel of oil (about 300 pounds) and preferably 6 to 18.

The hydrocarbon lubricant stock to which the process is applied may be a raw oil, i. e., a fluid hydrocarbon having a viscosity at F. of 10 to 500 centistokes, such as that used as the base for the 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.

In order to illustrate and point out some of the advantages of theinvention; but inno sense as a limitation thereof, the following specific embodiments are included.

In the following examples #300 Red Oil (a':

with the kind and amount of phosphorus sulfide indicated in the following table,;agitated-ford hour at 300 F., at atmospheric pressure. A. good yield is obtained, based on the hydrocarbon lubricating oil, and no sludge is formed in the phosphorus sulfide treating step. However, it is a preferred to filter the-final reaction product. In some-of the examples the clay treatment is usedbefore (third column), or after- (last column) or both, the phosphorus sulfide treatment, using the amounts of clay as indicated in the following table. The reaction product is identified hereinafter by the example number.

4 then with the clay makes some characteristics much worse than the raw oil alone, especially the viscosity increase, as shown on sample B and does not. materially help; Treating. the raw oil with the. phosphorus sulfide, and .then'with the acid, makes some characteristics worse than the raw oil alone, especiall the pentane insolubles andthe viscosity increase, as shown on sample C. This indicates thatthe phosphorus sulfide treatment.-must follow the acid treatment, as illustrated-byiExample 1.

In the following examples an S. A. 20 oil was used and the'treatment is evaluated in the table.

Amount-of 93 per cent ea Kind and Amount gF 'g f' E Sulfuric y of Phosphorus 8011- 3 sample 111 Lbs. s m Lbs umber Acid in er fidc 1n pe. cent by H Lbs. per g Weight of Hydro 1 Barrel 1 carbon Oil 0 o1 0.1 of on o 15 I s 0.2% ms; at 300 F; 7 l 8 0.2% P153 at 400 F 8 8 0.4%

The Sohio Corrosion Test was used in evalu-" ating lubricants made in accordance with the in; vention. This test is described in a copending Amount of Kind ml application of E. C. Hughea'J. D. Bartleson, MJL. 93 i -F Amount olPhos- 9".' Sunday and M. M. Fink, which also correlates the. Example a Sh Phmls Sulfide St res lt of th laborat r tests witha Chevrolet Number: Le. 2. asst by S 8 Y Barrel). Oil Weight of Hydro- Oil engine test.

on Essentially the laboratory test equipment con sists of a vertical thermostatically heated glass 10 0.4% rzsfl s test tube mm. outside diameter and 42 cm: is --g"-" long), into which is placed the corrosion test 10 5.1% 1 4's; 7.2 unit. An air inlet is provided for admitting air gg 5: 31 i into the lower end-of the corrosion unit in such 10 8 do... None a way that in rising the air'will cause the oil and 30 15 40 suspended material therein to circulate into the 1 Theacid treatment in this case is afterthe P285 treatment.

laboratory test procedures, as described in United States. Patent No. 2,403,474 at column 7, line 19 et seq; using the Standard test at 280 1 for 36 corrosion unit. The tube is filled with an amount of the oil'to be tested which is at least sufiicient to submerge the metals being tested.-

Thecorrosion testunit essentially'consists in a circular relatively fine grained copper-lezid test piece of O. D., which has a flfl'diameter hole in its center (i. e., shaped like an ordinary'washhours. The results given in Table I are repreer).- The test piece has an exposed-copper-lead sentative. surface of 3.00 sq. cm. Of this surface area, 1.85

Table I Lubricant Example No A 1 2 3 4 5 B C Lacquer Deposit (inMgmsz). 89.6 8 12. 2 2.0. 1 0 0 60.9 66.7 Corrosion (in' mgms.) Wt.

loss 0f-O'u-Pb 16.4 l.'2' 2. 5 4 5. 7 1. 2 9. 3 1-4. 8 Pentane lnsolubles (in mgnL/lfl g. of lubricant) 3 85 185 216 88.5 89.3 135.0 643 794' Acid Number; 4.6 1.6 'l.8 1.6 0.41 0.41 6.9; 7.3 Viscosity Increase (SUS) 362 81 73 64 10 76 888 398 Appearance Rating D A B- A 13+ 13+ D C sq. cm: acts as a loaded bearingyand'is contacted by a part of the cylindrical surface of a'hardened steel drill rod'-(14" diameter and 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 own axis and the surface of the drillrod which contacts the bearing is not charged) The corrosion test unit means for holding the bearing and the drill rod is a steel tubing (15 long and I O. D.) which is attached to 'a support. A steel cup (1" long,"1 %f O. Dfibyi Merelytreating the raw oil-with the acid and I. D.) is threaded into the steel'tubegat thelower end. The cup has a diameterholein the bottom for admitting the oil into the corrosion chamber. Th copper-lead test piece fits snugly intothe 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 bearings whichare fixedly'set in the outer steel tubing, one near the top and one near the lower (threaded) end thereof. Several holes are drilled just above and just below the lower hearing 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' self-aligning yoke and pin coupling. This assures instantaneous and continuous alignment of the drill rod bearing member against the bearing surface at all times. A pulley is fitted to the top of'th'e steel shaft and the shaft is connected therethrough to a power source. The shaft is rotated at about 6'75 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 the oil through the chamber containing the test piece and out through the holes in the steel tubing.

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 ap proximately 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 due to soluble iron are the most important. They are empirically duplicated by the addition of a soluble iron salt. Those due to lead-bromide are duplicated by its addition.

The test was correlated with the L4 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 4 hour intervals to 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 washed with 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 catalyst is added and the air flow is started. Lead-bromide 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 rate- 70 liters/hour 'Iime10 hours 6 Catalysts-Stee1; Copper-lead bearing. 3 sq. cm. area of which 1.85 sq. cm. is a bearing surface; ferric 2-ethyl hexoate: 0.05% as FezOa in C. P. benzene; lead bromide: 0.1% as precipitated powder. Bearing assembly Load -grams 600 Speed --R. P. M. 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 corrosion is determined by reweighing 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 sufiicient 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.

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

These Table II data also show the marked improvements achieved in accordance with the invention using the sesquisulfide. It may be noted that the 400 F., reaction temperature used in Example 7 does not appreciably improve the reaction product, as compared to the 300 F., reaction temperature of Example 6.

By comparable procedures, using any known comparable phosphorus sulfide, or amount of phosphor-us 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., tetraamyl silicate, an alkyl ortho-carbonate, 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 intend- 7 ed to claimsuch variations and"'-modifi'cati6fis broadly, except'as'do not 'come -within -th scope ofthe appended claims."

I claim:

1. A method of processing lubricating' oil stock consisting essentially of hydrocarbo i mate'rial to yield an -oilhaving improved-inhibition to oxidation in service, which method comprises treating said stock with sulfuric acid inaconventional manner, then treating the resulting acid-refined hydrocarbon with an amount in'the range of about 0.1 to about"0.75% by Weight of a phosphorus-sulfide at a temperature in the range of about-275 -to 450 F., and including. a separate clay-treating step subsequent to the acid-refining step.

2. The method of claim.1 wherein the hydrocarbon is treated with an amount of phosphorus pentasulfide in the range of about 0.1 to about 0.75%.

3. The method of claim 1 wherein the hydrocarbon is treated with an amount of phosphorus sesquisulfide in the range of about l1'to about 0.75%.

4. The method of claim3 wherein' the'hydi'ocarbon is treated with an amountof phosphorus sesquisulfide in the range of about 0.1 to about 0.6% at a temperature of about'300? td 450 F.

5. The method of claim 2 wherein 'the" claytreating step is subsequent to the phosphorus pentasulfide treating step.

6. The method of claim- 2 wherein-the'claytreating step is just prior to the phosphorus pentasulfide treating step. i

7. The method of claim 5 wherein the hydrocarbon is treated With an amount'of phosphorus pentasulfide in the range of about 0.25'to about 0.6% at a temperature in the range of about 300 to 450 F.

8. The method of claim 6 followed by an additional final treatment with clay.

:9. Thef'methodtofclaim 8- whereinzthvhydrocarbon is treated with an amount of phosphorus pentasulfide in. the range of about 0.25 to-about 0.6% at a temperature in the range of about 300 to'450" F.

10; The method of claim 9 wherein-the amount of the phosphorus pentasulfide is 0.4%.

11; The'refine'd lubricating oil obtained by the process of claim 1.

12. Therefined lubricating oil obtained' by'the process of claim 2.

13. The refined lubricating oil obtained the. process 'of claim 3.

' 14. The refined lubricating oil' obtained-by the process .of. claim 4. g

15. The refined lubricating oil obtained by: the processzof claim 5.

\ 16; The refined lubricating oil obtained-by the process of claim 6.

17; The re'fined'lubricating oil obtained [bye-the process of claim 7.

118. The refined lubricating oil obtained-bythe process of claim 8.

19.:The r'efined lubricating oil obtained bythe process'of claim 9.

20. The refined lubricating"oilobtainedby the process of claim 10.

JOHN D. BARTLESON.

REFERENCES CITED 'The following references are of record in -the me of this patent:

' UNITED STATES PATENTS

Claims

1. A METHOD OF PROCESSING LUBRICATING OIL STOCK CONSISTING ESSENTIALLY OF HYDROCARBON MATERIAL TO YIELD AN OIL HAVING IMPROVED INHIBITION TO OXIDATION IS SERVICE, WHICH METHOD COMPRISES TREATING SAID STOCK WITH SULFURIC ACID IN A CONVENTIONAL MANNER, THEN TREATING THE RESULTING ACID-REFINED HYDROCARBON WITH AN AMOUNT IN THE RANGE OF ABOUT 0.1 TO ABOUT 0.75% BY WEIGHT OF A PHOSPHORUS SULFIDE AT A TEMPERATURE IN THE RANGE OF ABOUT 275* TO 450* F., AND INCLUDING A SEPARATE CLAY-TREATING STEP SUBSEQUENT TO THE ACID-REFINING STEP.