US2691002A

US2691002A - Method of processing solvent-ex

Info

Publication number: US2691002A
Authority: US
Publication date: 1954-10-05
Anticipated expiration: 1971-10-05

Description

REA arm Patented Oct. 5, 1954 UNITED STATES PATENT OFFICE John D. Bartleson, Cleveland, and Harvey E.

Alford, Amherst, -Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio N Drawing. Application August 27, 1952, Serial No. 306,726

12 Claims.

This invention relates to a process of improving hydrocarbon base lubricants, and more particularly, to a process of treating solvent-extracted hydrocarbon lubricants with a small amount of phosphorus pentasulfide followed by treatment with potassium hydroxide to form lubricants having improved properties and to the resulting improved lubricants. The process is one of treating the entire body of oil to be used as a lubricant as distinguished from the manufacture of an additive for a lubricant.

Many of the commercially used lubricants are derived from hydrocarbon base stocks which may be prepared synthetically or which may be obtained from natural sources such as petroleum. In order to provide a lubricant having desirable characteristics, and particularly detergency, additives usually must be included in the stock. Solvent-extracted oils, for example, require the addition of additives to impart detergency thereto.

In U. S. Patent No. 2,560,546, dated July 17, 1951, to John D. Bartleson, a process of treating solvent-refined hydrocarbon base lubricating oil stocks has been described which imparts detergency thereto, thus avoiding the necessity of adding additives for this purpose. According to the process outlined in that patent, the solventrefined hydrocarbon lubricating oil stock is reacted with a small amount of phosphorus pentasulfide and then with up to eight equivalents of a base per mol of the sulfide used. Such lubricants have good antioxidant and corrosion inhibition properties, and are suitable for use under various conditions including high temperatures or high pressures, or both, as for instance, 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 lubricents, e. g., in oils and greases containing the same, The resulting reaction products thus can be described as chemically finished 0r refined improved lubricants, relative to the untreated solvent-refined hydrocarbon lubricating oil stock.

In accordance with the instant invention, it has been found that if the base employed in reacting with the phosphorus pentasulfidetreated solvent-refined hydrocarbon lubricating oil stock is potassium hydroxide, and an amount of base in excess of eight equivalents per mol of the sulfide is used at a reaction temperature in excess of 325 F., different products having especially desirable properties are obtained. Such products have a higher alkaline number, a higher ash content, and improved storage stability, and in service show improved detergency and. anti-acid-wear properties. Thus the products are quite different, in an unexpected way. In contrast to the products prepared in accordance with U. S. Patent No. 2,560,546, the products of the invention tend to be relatively poorer in oxidation inhibition and corrosion inhibition properties, although still better than the untreated oil in these respects. This, of course, can be corrected by addition of any antioxidant.

The reaction of the solvent-refined hydrocarbon base stock with the phosphorus pentasulfide can be carried out as set forth in the aforesaid U. S. Patent No. 2,560,546 to John D. Bartleson. Thus, the reaction may be conducted with direct admixture of the stock with the phosphorus pentasulfide, or, if desired, by their admixture in the presence of a diluent which may be subsequently removed. Generally a diluent is not necesssary. The reaction usually is complete in about ten hours or less time; generally from one to two hours. The reaction time is a function of the temperature, the amount of sulfide that is to react, the degree of sub-division of the reactants,

3 the efficiency of mixing the reactants, and the like.

The hydrocarbon lubricating stock to which the process is applied is a solvent-extracted or solvent-refined oil, i. e., oils treated in accordance with conventional modern methods of solvent-refined lubricating oils. The oil may be a fluid hydrocarbon lubricating base stock having a viscosity at 100 F. of to 500 centistokes, such as is used as the base for SAE No. 10 to 50 oils. It may be obtained as a distillate or from synthetic materials, such as petroleum, and oils produced by cracking, polymerization, dehydrogenation, and the like methods are also contemplated. The solvent-refining process is well known and generally involves a physical separation of impuritiesfromthe oil by extraction with a solvent. Uusually'the solvent selectecLsuch as furfural, phenol, sulfur dioxide, etc., dissolves such constituents as aromatic, unsaturated and low viscosity index materials, and these are separated. A clay treatment may follow, but while this is desirable, it is not essential. Where necessary, a separate propane or the like deasphalating treatment may be used in conjunction with the solvent-refining.

The solvent-refined hydrocarbon lubricating stock is reacted with the phosphorus pentasulfide in a ratio within the range from about 0.1 to about 0.75% by weight, based on the weight of the stock, desirably about 0.25 to about 0.60%, and preferably about 0.4 to about 0.6%. Higher amounts of the pentasulfide give products which are inferior to the hydrocarbon as to viscosity increase. Generally at least about 0.1% thereof should be used to achieve the desired result, although smaller amounts show some improvement.

The reaction of the solvent-refined hydrocarbon stock with the phosphorus pentasulfide can be carried out in the presence or absence of air or in an atmosphere of inert or non-deleterious gas such as nitrogen. It may also be carried out under pressure, such as the pressure enerated when the reaction is carried out in a closed vessel due to the liberation of gases in the course of the reaction.

During the reaction, nitrogen or other-inert gas can be bubbled through the reaction mixture. This assists in the removal and dissipation of hydrogen sulfide, shifting the reaction towards the desired end product and thus shortening the time required to complete the reaction.

The refining temperature varies with the hydrocarbon stock. Generally the treatment should be at least at 275 F. but should be below the temperature at which the reaction product would be decomposed. A temperaturein the range of about 300 to about 450 F. is preferred in many cases. The reaction product preferably is centrifuged or filtered to remove by-products, sludge or other material. A volatile diluent, if present, can be removed by evaporation or distillation.

The solvent-refined oil stock so treated is then treated with potassium hydroxide. This reaction can be carried out at a temperature of about 325 to 400 F., preferably 350 F. The sulfur content decreases with rising temperatures, while storage stability increases. Ash and alkaline number are at an optimum at 350 F. Ash and alkaline number are a measure of detergent properties. At temperatures above 400 F. the oil may begin to darken, which may be undesirable although it does not affect the good qualities of the reaction product, and the alkaline number also drops. At temperatures below 325 F. the beneficial results 4 obtainable from the use of the higher quantities of the potassium hydroxide are not realized.

If air is brought into the reaction mixture during the reaction of potassium hydroxide with the phosphorus sulfide-treated oil a larger amount of potassium hydroxide will react. Apparently the acidity of the material reacting with the po tassium hydroxide is increased possibly due to oxidation, so that more acid groups are made available for reaction with potassium hydroxide. Therefore, although good results are obtained without introduction of air, to obtain the maximum effect from the use of large amounts of potassium hydroxide, i. e., maximum utilization of the potassium hydroxide, from the standpoint of alkaline number and ash weight of the product. it is desirable to introduce air. The amount of air is not critical, the improvement increasing in proportion to the volume of air used. Amounts up to about 8 liters of air per grams of reaction mixture have been found to give satisfactory results, but more could be used if desired.

More than eight equivalents of potassium hydroxide are used per mol of the sulfide used in the solvent-refined stock, preferably 10.5 equivalents. There is no critical upper limit to the amount of potassium hydroxide except that more than will react with the solvent-refined stock would not be used because it would be filtered off as an unreacted material. Twelve equivalents have given excellent results, and sixteen equivalents have also been satisfactory.

Expressed on a weight basis, the amount of potassium hydroxide used should be more than two parts of potassium hydroxide to each part of sulfide used in the solvent-refined stock, preferably three parts of potassium hydroxide to each part of sulfide, by weight. A 4:1 ratio has been used and more than a 4:1 ratio of potassium hydroxide to sulfide could be used, if desired.

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

Examples 1 to 23 In these examples the hydrocarbon stock was a blend of 88.5 parts of 300 solvent-extracted neutral oil (300 SSU at 100 F.) and 5 parts each of bright stocks of '78 and 250 SSU, respectively, at 210 F. These stocks were refined by furfural extraction, methyl ethyl ketone dewaxing and clay treating, and are a good grade of solventrefined oil, available on the market, and typical of. such an oil.

The phosphorus pentasulflde was mixed with the hydrocarbon lubricating oil in the amounts indicated in the following table, and reacted for the time and at the temperature indicated, at atmospheric pressure in an open vessel, While blowing nitrogen through the reaction mixture. The base used was potassium hydroxide in the dry-appearing flake form containing about 12% water, and therefore 88% active KOH. This was reacted for the time and at the temperature indicated, while blowing nitrogen through the reaction mixture, which was in an open vessel exposed to the atmosphere. A11 weight per cents of potassium hydroxide in the table have been corrected to give the amount of active potassium hydroxide available for reaction. The product analysis also is included in the table. The examples identified by alphabetical letters are the intermediate phosphorus pentasulfide-oil reaction products, which were subsequently neutralized by treatment with potassium hydroxide.

Reaction Mols oi Conditions Pwdm Analysis His Sta- Example Percent Percent KOH bility in No. P15 KOH per mol storage at of P 8 Time Temp., Percent Percent Percent Alkaline F (Hrs) F. s Sulphur Phos. No.

None 1 300 O. 335 0.093 5 hrs. 1.06 10. 5 2 350 1. 33 0.26 0.095 4. 29 2 mos 1. 06 10. 5 2 350 1.48 0.25 0.097 4. 22 2 mos 1.06 10. 5 2 350 1. 27 0.32 0.077 4. 59 2 mos None 1 300 0. 45 0.110 5 hrs. 1.06 10. 5 2 360 l. 09 0. 30 0. 11 4. 94 2 mos None 1 300 5 hrs. 1.06 10, 5 2 350 0.815 0.285 0. 1O 4. 14 2 mos None l 300 0.315 0.056 5 hrs. 1. 06 10. 5 2 350 1.16 0. 215 0.053 3.88 2 mos None 1 300 0.335 0. 093 5 hrs. 0.7 7.0 2 350 1.0 0. 235 0.095 2. 33 2 mos 1.06 10. 5 2 250 O. 0.26 0.073 1.01 2 mos None l 300 0.385 5 hrs. 0.7 7 0 2 250 0.430 0.285 1.03 5 hrs. None 1 300 0. 390 5 hrs. 0. 8.8 2 250 0.395 0. 325 0.82 5 hrs. 1. 06 10. 5 2 250 O. 442 0.280 1.13 5 hrs. None 1 300 0.365 5 hrs.

1.06 7.0 2 350 1. 56 0. 345 4. 30 10 days 1. 58 10. 5 2 350 1.95 0. 300 6. 83 2 mos None 1 300 0. 445 5 hrs. 2.1 10. 5 2 350 1. O. 390 4. 96 2 mos None 1 300 .1 0. 415 5 hrS.

0. 7 7.0 2 350 1.04 0.295 2.16 2 mos. 2. 1 2 1 350 1. 84 0. 16 7. 28 1 mo.

1 Blown with air during reaction.

Examples 1-6 and 16 are all oils treated with 10.5 or twelve equivalents of KOH per mol of P285 and the amount of P285 used is 0.4%. These seven oils show a high ash content, sulfur content, alkaline number and Has storage stability, indicating superior detergency and anti-wear properties, compared to Examples 7 and 15 where only seven equivalents of KOH are used per mol of P285. Examples '7 and 15 have good antioxidant and corrosion inhibition properties, but Examples 1-6 and 16 are better in detergency and anti-wear properties.

It will be noted that the reactions of KOH with the P285 treated oil in Examples 1-6 and 15' and 16 were carried out at 350 F. Examples 8-11 est ash content and alkaline number of all of the products shown in the table.

Example 14 shows the benefits obtainable at 0.8% P285, the upper limit of phosphorus pentasulfide.

It is readily. seen from the above data that Example 13 is the best product of the group and the remainder, with the exception of Examples '7, 9, 12 and 15, are good equivalent products.

In the following, nitrogen and in some cases air are blown through the reaction mixture during the reaction of the phosphorus sulfide-oil reaction product with potassium hydroxide, and the reaction was carried out in a closed vessel to exclude atmospheric air:

M 1 Reaction Conditions Lit Percent Percent 0 es ers Percent Percent Percent Alkaline No. 150 Example No. KOH per added per P785 KOH mole P 8 Time Temp. Air Blow- 100 oil S] P Ash Total (hrs.) F.) ing 1 300 2 350 NOBEL. O. 0. 095 0. 74 2. 67 8 2 350 41./100 g 4 0. 095 0. 088 1- 55 5- 03 30 2 350 81.]100 g... 8 0.110 0. 088 1. 71 6. 22 30 2.4% KOH 1 300 2 350 None 0. 225 0. 0. 94 4- 18 8 2 350 41/100 g.. 4 O. 175 0. 120 1. 89 6. 76 30 2 350 81./1U0 g 0. 220 O. 110 2. 07 7. 37 30 1 Corrected for sulfur in the base oil.

Examples 16, 19 and 21 were stable to liberation of H20 for one month at room temperature. However, Examples 17, 18, 20, 22 and 23 were markedly superior in HzS stability at F. In

addition to improved HzS storage stability, air blowing also increases ash weight and alkaline number, showing a large amount of potassium hydroxide has reacted, without appreciable less in sulfur and phosphorus. Thus detergency is improved while sulfur content remains high enough to obtain satisfactory corrosion inhibilents of KOH. In fact, Example 13 has the high- 75 tion.

Example 4 was subjected to the L-4 Chevrolet engine test. The test duration was 36' hours. The following results were obtained:

Varnish total 47.50

Skirt 9.25 Sludge total 47.50 Corrosion/half-shell mgs 98.1 Used oil properties:

Vis. Inc 0.4

Per cent C5-Insols 0.1

Neut. No 0.99

Demerit rating 2.77-

This data shows that the oil gives satisfactory performance as an engine lubricating oil.

An engine wear test gave a 0.072 gram total ring weight loss for the oil of Example 6 ascompared with 0.1692 gram total ring weight loss for the base oil. This demonstrates the high antiwear characteristics of the treated oilof the invention.

The greatly improved characteristics of the chemically refined or finished lubricants of the invention, particularly with respect to odor stability, detergency and anti-acid wear is especially noteworthy since these are major problems with conventional solvent-refined oils. If desired, the improved lubricants of the invention can be used in blends together with other lubricants or other lubricant agents such as soap or the like in a grease.

An antioxidant usually would be added in service to oils treated by the invention. Any antioxidant can be used, such as dibutyl-p-cresol, sulfurized terpenes, dialkyl zinc dithiophosphates and tetramethyl-diamino-diphenyl methane.

An agent for improving the clarity of the oil'' may be included, e. g., lauryl alcohol and the like. Agents for preventing foaming may also 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 intended to claim such variations and modifications broadly except as do not come within the scope of the appended claims.

We claim: 1

1. A method of processing solvent-extracted lubricating oil stock consisting essentially of hydrocarbon material to yield an oil having improved properties in service which comprises treating said stock with an amount of phosphorus pentasulfide 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 potassium hydroxide in an amount more than eight 8 equivalents per mol of the phosphorus pentasulfide at a temperature of at least 325 F.

2. The method of claim 1 wherein the sulfi'de-treated stock is reacted with potassium hydroxide at a temperature within the range of about 325 to about 400 F. in an amount in the range of more than eight to about sixteen equivalents per mole of the phosphorus pentasulfide.

3. The method of claim 2 wherein the stock is treated with an amount of phosphorus pentasulfide in the range. of about 0.4'to about 0.6% and then with an amount of potassium hydroxide in the range of more than eight to about sixteen equivalents per mole of the phosphorus pentasulfide.

4. A lubricant obtained by the process oi! claim 1.

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

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

7. A method of processing solvent-extracted lubricating oil stock consisting essentially of hydrocarbon material to yield oil having improved properties in service which comprises treating said stock with an amount of phosphorus pentasulfide in the range of about 0.1 to about 0.75% by weight at a temperature in the range of about 275 to about 450 F. and then with an amount of. potassium hydroxide of more than three parts by weight to each part by weight of the phosphorus pentasulfide at a temperature of at least about 325 F.

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

9. A method in accordance with claim 7 in which the reaction with potassium hydroxide is carried out while blowing air through the reaction mixture.

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

11. A method in accordance with claim 1 in which the reaction with potassium hydroxide is carried out while blowing air through the reaction mixture.

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

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,466,408 Funk Apr. 5, 1949 2,476,813 Buckmann July 19, 1949 2,483,571 Brennan Oct. 4, 1949' 2,560,546 Bartleson July 17, 1951

Claims

1. A METHOD OF PROCESSING SOLVENT-EXTRACTED LUBRICATING OIL STOCK CONSISTING ESSENTIALLY OF HYDROCARBON MATERIAL TO YIELD AN OIL HAVING IMPROVED PROPERTIES IN SERVICE WHICH COMPRISES TREATING SAID STOCK WITH AN AMOUNT OF PHOSPHORUS PENTASULFIDE 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 POTASSIUM HYDROXIDE IN AN AMOUNT MORE THAN EIGHT EQUIVALENTS PER MOL OF THE PHOSPHOROUS PENTASULFIDE AT A TEMPERATURE OF AT LEAST 325* F.