US2895978A - Process for oxidizing petroleum oil and products thereof - Google Patents

Description

2,895,978 Patented July 21, 1959 PROCESS FOR OXIDIZING PETROLEUM oIL AND PRoDUcTs THEREOF John W. Brooks, Wenonah, NJ., assignor to Socouy Mobil Oil Company, Inc., a corporation of New York No Drawing. Application July 6, 1954 Serial No. 441,626

4 Claims; (01. 260-451) The invention has to do with the oxidation of petroleum oils and the products produced thereby. More specifically, it relates to a novel method for oxidizing petroleum oils to produce a new class of metal-containing oxidized oil products. The invention also contemplates the use of the new metal-containing oxidized oil products as detergents in mineral lubricating oils.

The oxidation of petroleum oils to produce acidic products and the conversion of these products to metal salts has been known heretofore. Thus, petroleum oils have been oxidized, in some instances, in the presence of catalytic amounts of alkaline materials, such as metal hydroxides, and then converted to normal salts by reaction with polyvalent metal hydroxides, either before or after separation from the unoxidized portion of the oil. These normal salts of oxidized oils have been utilized as lubricating oil additives, particularly as extreme pressure agents.

The present invention, however, is predicated on the I discovery that when petroleum oils are oxidized in the presence of excess amounts of basic metal salts, such as metal hydroxides, metal-containing oxidized oil products are produced which contain higher equivalent amounts of metal than the normal salts, or soaps, of oxidized oil products known heretofore. Thus, the metal salts provided by the method of this invention contain about 2.0 equivalents of metal per equivalent of acid-hydrogen formed during the course of the oxidation. These new products are, therefore, not normal salts of oxidized oils, but complex salts as will be shown hereinafter. These complex oxidized oil salts are excellent detergents for mineral lubricating oils. As far as is known, the oxidaever, the best detergents are provided when an excess of at least about 45 weight percent of the metal hydroxide is used. Conversely, the amount of the metal hydroxide to be utilized in the oxidation will range from a minimum of about 5% to a maximum of about 85% of that charged to the oil.

Broadly stated then, it \m'll be seen that the present invention provides a process for the preparation of a metal-containing oxidized oil product which comprises oxidizing a petroleum oil, in the presence of from about 2% to about 25%, by weight, of a metal hydroxide, to an extent such that from about 5% to about 85% of the metal hydroxide is incorporated into the oil and then filtering the reaction mixture to separate unreacted metal hydroxide from the metal-containing oxidized oil product.

In practicing the invention, the oil and the metal hydroxide reagent are mixed together in a suitable reactor having means for introducing the oxidizing gas, i.e., air or oxygen. The mixture is then heated to a temperature of from about 250 F. to about 600 F., preferably about 350450 F., while passing the oxidizing gas therethrough. The oxidation is continued for a time sufficient to effect reaction of from about 5% to about 85% of the metal hydroxide with the oxidized oil. The oxidation is then stopped and the reaction mixture 7 filtered and cooled.

tion of petroleum oils has never been conducted in the become apparent from the following description of the F invention.

By the term excess of metal hydroxide reagent, as used herein, is meant the addition to the oil, prior to the oxidation reaction, of an amount of the metal hydroxide over and above that which is eventually taken up by the oil during the oxidation. weight per cent of the metal hydroxide charged to the oil should be at least about 2% and may feasibly be as high as about 25%. It will be appreciated that the extent to which the oxidation is carried out will determine how much of the charged metal hydroxide reagent is taken up by the oil. It has been found that a substantial proportion, i.e., about 15%, of the charged amount of the metal hydroxide must remain unreacted at the termination of the oxidation if the resulting products are to be effective lubricating oil detergents. How- It is another object of the invention to provide a 5'7 The actual amount in terms of I? As aforesaid, the amount of metal hydroxide charged to the oil shall be from at least about 2% to about 25 based on the weight of the oil. Greater amounts may be used, but are not desirable from a practical standpoint as too great a proportion of the metal hydroxide reagent creates difficulties in handling and filtering the product. However, in instances where the filtration is diflicult it may be facilitated by diluting the product mixture with a suitable solvent prior to the filtration operation. Such solvents as cyclohexane, toluene, benzene, xylene and the like may be used. After the filtration the solvent is removed from the product by distillation.

The oxidation time in any case, of course, will depend upon several factors. Thus, the temperature of reaction, the type of oil stock employed, the rate of introduction of the oxidizing gas and the efliciency of the contacting of the oxidizing gas with the oil all effect the oxidation time. The quality of the product obtained, however, depends upon the amount of metal hydroxide remaining upon completion of the oxidation, or in other words, the extent to which the oxidation is carried out. It will be' appreciated that a suitable oxidation time in any case can be determined by conducting several oxidations for different periods of time, while maintaining the other reaction variables constant, and nothing the amount of metal hydroxide remaining unused in each instance. The proper oxidation time then will be that which provides the required excess of metal hydroxide. As will be seen from the examples highly satisfactory products have been obtained using oxidation times varying from a few hours up to as high as hours or more, depending upon the reaction conditions employed. From a practical standpoint it is, of course, ordinarly desirable to utilize reaction conditions which are conducive to'effecting the oxidation to the required extent in the shortest possible period of time. Accordingly, it is considered that modifications of the process designed to increase the efiiciency of the oxidation, such as by the use of known oxidation catalysts, special reactors and the like, are clearly Within the broad purview of this invention.

The metal hydroxide reagents utilizable for the preparation of the metal-containing oxidized oil products of the invention are those of the metals of Group II of Mendeleeifs Periodic Table of the Elements. Specifically, the hydroxides of calcium, barium, strontium, zinc and magnesium are suitable with calcium hydroxide eing particularly preferred. Various commercial grades of calcium oxide, calcium hydroxide and barium hydroxide are suitable for use in the invention. However, Grease Makers Lime (96% calcium hydroxide) is preferred because of its high purity, small particle size and its property of being wetted by the oil.

The oil to be oxidized may be any petroleum oil or light, medium or heavy grade, the chief limiting factor with respect thereto being the solubility in oil of the resulting product, as these products are contemplated particularly for use as detergents for lubricating oils. Generally, suitability from this standpoint requires that the oil have an average molecular weight of at least about 300. However, heavier oils having molecular weights of from about 600 up to about 1000 are particularly suitable. The use of conventionally refined oils having molecular weights in the latter range are especially preferred from the standpoint of solubility in oil of the resulting products. In terms of viscosity, oils having viscosities ranging from about 20 to 300 S.U.V. at 210 F. may be used, with those of from about 100 to 200 S.U.V. at 210 F. being preferred. The characteristics of several highly suitable oil stocks are shown in Table I.

4 the bottom. Sixty liters of air per hour were passed up through the oil at 400 F. for 24 hours. A portion of the reaction mixture was contacted with 4 weight percent of Hyflo and filtered. Analysis showed that the product contained 1.67% calcium. The excess calcium hydroxide in this instance was 71%.

The column reactor used in this example provides a much more efficient use of the oxidizing gas than the flask reactor utilized in the previous example, so that the time of oxidation is made much shorter.

Example 3 Twelve hundred grams of a percolated, solvent-refined Mid-Continent type bright stock and 87 grams of calcium hydroxide (7.25 weight percent) were charged to a flask reactor of the type used in Example 1, but in this case only two filter sticks for introduction of air were used. Ten liters of air per hour were bubbled into the stirred oil through each filter stick. The temperature was maintained at 375 F. during'the oxidation. The time of oxidation was 54 hours. After air introduction was stopped, the reaction mixture was stirred with 48 grams (4 weight percent) of Hyflo filter-aid and then filtered hot. The product thus obtained contained 1.12 weight percent calcium. The unused calcium hydroxide amounted to 72% of that charged to the reaction.

TABLE I.-PROPERTIES OF OIL STOCKS Specific Avg. SUV (Sec) Oil type gram, API Aniline mol. Percent V.I. Flash,

60/60 grav. pt., 0. wt. S F.

Percolated Mid-Continent Bright Stock..." 0.8996 25. 8 119. 2 720 0.7 1, 848 123. 8 94 525 Unpcrcolated M id-Continent Bright Stock" 0.8950 26. 6 121.2 880 1,903 125. 5 93. 5 East Texas Hvy. Waxy Dist. Stock 26, 9 470 0. 24 619 66.8 85 495 A full understanding of the process of the invention and of the nature of the products produced thereby may be had by reference to the following specific examples.

Example 1 Five thousand grams of a solvent-refined Mid-Continent bright stock and 1000 grams (20 weight percent) of calcium hydroxide were charged to a 3-liter, round-bottomed, 4-necked flask equipped with a stirrer, a thermometer and 6 medium-grained filter sticks for introduction and dispersion of air. The reaction mixture was heated and maintained at a temperature of approximately 375 while air was passed therethrough at a rate of liters per hour per filter stick for 78 hours. The introduction of air was then stopped, the reaction mixture was stirred with about 4 weight percent of Hyflo (a diatomaceous earth filter aid), filtered and cooled. The filtered oil product contained 1.50% calcium. The excess calcium hydroxide remaining unreacted was 86% of that charged.

As stated hereinabove, the metal-containing oxidized oil products of the invention contain about two equivalents of metal per equivalent of acid-hydrogen produced in the oxidation. To demonstrate this, the product obtained above was de-metallized by treatment with hydrochloric acid. The resulting material had a neutralization number (N.N.) of 21 and 'a saponification number (S.N.) of' 18. This neutralization number accounts for only 50% of the actual calcium content of the oxidized oil product. Accordingly, it must be concluded that the remaining 50% of the calcium is present as some type of coordinated, complexed or double salt.

Example 2 Two thousand grams of an unpercolated solvent-refined Mid-Continent bright stock and 218 grams (11 weight percent) of calcium hydroxide were charged to an electrically heated column reactor, 60 in. long by 3 in. in diameter, equipped with a fritted glass plate sealed in Example 5 A percolated, Mid-Continent bright stock of somewhat longer residum than that used in Example 4 was oxidized as in Example 4, but here the oxidation time was 50 hours and three air-inlet bubblers were used at 10 liters of air per hour per bubbler. The filtrate contained 1.29 weight percent of calcium, which accounted for 35% of the calcium charged to the reaction.

Example 6 The experiment of Example 5 was repeated with two changes. Only 29 grams of calcium hydroxide (2.4 weight percent) was used and the oxidation time was 68 hours. The filtrate contained 1.14 weight percent of calcium. The excess calcium hydroxide in this case was 11%.

Example 7 Example 4 was repeated, but 198 grams of calcium oxide was used. The filtrate contained 2.48 weight percent of calcium, which accounted for 25% of the calcium 70 charged to the reaction.

Example 8 Example 4 was repeated, but here the air was introduced through a single jet at 20 liters per hour and an oxidation time of 96 hours was used. The filtrate conen a /e Example 9 Two thousand and severity grams of an SAE 20, percolated, solvent-refined Penna, neutral-bright stock mixture and 150 grams of barium hydroxide (7.2 weight percent) were charged to a flask reactor of the type used in Example 4. One coarse-grained filter stick was used for introduction and dispersion of the oxidizing gas, which in this instance was oxygen. The oxygen rate was 0.34 liter per hour. The temperature was 490:10" F. The oxidation time was 66 hours. After oxygen introduction was stopped, the reaction mixture was diluted with an equal volume of cyclohexane. Hyflo filter-aid was added and the reaction mixture was filtered. The filtrate was topped to 350 F. at about 150 mm. pressure to remove solvent. The solvent-free filtrate contained :1 weight percent of barium, which accounted for 93% of the barium charged to the reaction, the excess barium being 7%.

Example 10 Three hundred and twenty-six grams of an SAE 20, percolated, solvent-refined Penna. neutral bright stock mixture and 74 grams of calcium hydroxide (10 weight percent) were charged to a flask type reactor equipped with a stirrer, a thermometer and one filter stick for introduction of air. The rate of air introduction in this instance was undetermined. After oxidation for 51 hours at a temperature of 480 F., the reaction mixture was diluted with cyclo'hexane and the product recovered as in Example 9. The solvent-free filtrate contained 1.04 weight percent calcium, which accounted for 10% of the calcium charged to the reaction.

Example 11 Example 10 was repeated using 350 grams of the oil and 50 grams of barium hydroxide in place of the calcium hydroxide. The absolute air rate was unknown here also, but it was the same as that used in Example 10.

.The solvent-free filtrate contained 4.26 weight percent barium, which accounted for 43% of the barium charged to the reaction.

DETERGENT ABILITY As is well known, internal combustion engine lubrieating oils, under the severe oxidizing conditions encountered in use, gradually deteriorate with attendant formation of sludge, lacquer and resinous materials which adhere to the engine parts, particularly the piston ring grooves and skirts, thereby lowering the efliciency of the engine and frequently causing the rings to stick. To counteract this condition, it has become the common practice in the art to fortify such oils by the addition thereto of minor amounts of chemical agents which have the ability to keepthe deposit-forming materials suspended in the oil and which thereby keep the engine in clean and efiicient operating condition for extended periods of time. Such chemical agents are known as detergents. As mentioned hereinabove, the metal-containing oxidized oil products produced by the method of this invention are excellent motor oil detergents, This has been shown by a series of engine tests conducted on ,oil blends of a number of the products shown in the preceding examples. The tests used were the Lauson D4-A detergency test and the CFR diesel D2l detergency test which are described below. All the products were com pared on an equivalent metal basis, viz., 0.058 weight percent for the calcium products and 0.2 weight percent for the barium products in the Lauson engine test; and, 0.088 weight percent for the calcium products and 0.3

.Weight percent for the barium products in the CFR diesel engine test. The test results are summarized in Table II. As indicated in the table, to some of the oil blends tested there was also added 1% of an anti-oxidant additive (a pinene-P S reaction product). This is a common prac' tice in evaluating oil detergents.

LAUSON ENGINE TEST follows:

Oil temperature F... 225 Jacket temperature F 275 Speed r.p.m 11825 Brake load H P 1.6

One-half throttle. 13-1 air-fuel ratio. Oil added every 20 hours (one-gallon sample used).

The duration of the test is hours.

CFR DIESEL ENGINE TEST This test determines theeifectiveness of the lubricating oil in preventing piston deposits and top ring wear.

A single cylinder, CPR, 4-cycle, super-charged diesel engine is used. The operating conditions are as follows:

Oil temperature F Jacket temperature F-.. 212 Speed r.p.m 1800 Brake load H.P 7.5 Oil addition every 8 hours starting at 4 hours (1 /2 gal. sample used). Heat input B.t.u./min 1260 The duration of the test is 60 hours. The results are reported in terms of piston cleanliness ratings as in the D 4A test.

Referring to Table II, it will be seen that the products produced according to the process of the invention, i.e., utilizing the prescribed excess amount of metal hydroxide reagent, were all effective detergents. On the other hand, the products produced utilizing less than the specified excess amounts of the metal hydroxide were not effective as detergents. See Examples 6 and 9. Furthermore, it will be noted that the products of these latter examples actually contained higher amounts of metal on a weight percent basis than several of the products which were good detergents. The necessity for the utilization of an excess of the metal hydroxide reagent as defined herein to provide a product having detergent ability is, therefore, evident.

It will be appreciated that the products of the invention are actually oil solutions of the complex oxidized oil salts and although the products shown in the examples presented herein vary with respect to their complex salt content, it will be understood that these dif ference can be eliminated by standardization of process procedure and also when required by distillation of a portion of the oil therefrom. The amount of-product required to be added to a lubricating oil to provide the desired increase in the detergent ability thereof will, therefore, vary depending upon the process conditions utilized in preparing the particular products. In general, however, the amount of the product to be utilized will range from about 1% to about 10%, by weight, the usual amount being from about 2% to about 5%.

The products of the invention may also be added to oils containing other additives designed to improve the various characteristics thereof, such as antioxidants, pour point depressants, viscosity index improvers, defoamants, rust preventives, etc.

Although the products of the invention are intended primarily for use as detergents for lubricating oils, they are also utilizable for many' of the purposes for which.-

'7 metal salts of organic acids are used, e.g., as components in coating compositions, paint driers,detergent soaps, dispersants, rust-preventive compositions, etc.

Although the invention has been described herein by means of certain specific embodiments and illustrative examples, it is not intended that it be limited in any way thereby, but only as indicated in the accompanying claims.

TABLE II.ENGINE EVALUATION to about 600 F., to eflfect oxidation of said oil and reaction of said calcium hydroxide with the oxidized oil, (3) continuing said oxidation for a time sufficient to effect the reaction of at least about 5% but not more than about 55%,of said calcium hydroxide and (4) subjecting the resulting reaction mixture to filtration to separate the calcium-containing oxidized oil product.

Lauson engine test Diesel engine test Percent Metal excess Percent Product hydroxide metal metal in reactant hydroxide product Percent l-h0ur Percent 60-hour product deterproduct deterin oil 1 gcncy in oil 2 gency rating rating Example 2 None Example 3 Ca(OH) 72 1.16 5.0 Example 4 Ca(OH) 45 2. 03 2. 9 Example 5 Oa(OH) 65 1.29 4. 5 Example 6--- Ca(OH) 11 1.14 5.1 Example 7 Ca(0H) 75 2. 48 2.3 Example 8 Ca(OH) 55 1.63 3.6 Example 9. Ba(OH) 7 5.1 6.0 Example 10. Ca(OH) 90 1. 04 5. 6 Example 11 Ba(OH) 57 4. 26 4. 7

1 SAE grad solvent-refined Penn. oil, K.V. at 100 F.=G3, K.V. at 210 F.=8.3. 2 SAE 30 grade solvent-refined Mid-Continent oil, K.V. at 100 F.=121, K.V. at 210 F. %)?1 blend contained 1% anti-oxidant (Pinene-Pzss reaction product).

What is claimed is:

1. A process for preparing a metal-containing oxidized oil product which comprises (1) forming a mixture comprising (a) a petroleum oil having a molecular weight of from about 300 to about 1000 and (b) from about 2% to about based on the weight of said oil, of a hydroxide of a metal of group II of the periodic table of the elements, (2) contacting said mixture with an oxidizing gas at a temperature of from about 250 F. to about 600 F., to efiect oxidation of said oil and reaction of said metal hydroxide with the oxidized oil, (3) continuing said oxidation for a time sufiicient to effect the reaction of at least about 5%, but not more than about 55%, of said metal hydroxide and (4) subjecting the resulting reaction mixture to filtration to separate the metal-containing oxidized oil product.

2. A process for preparing a metal-containing oxidized oil product which comprises (1) forming a mixture comprising (a) a petroleum oil having a molecular weight of from about 300 to about 1000 and (b) from about 2% to about 25 based on the weight of said oil, of an alkaline earth metal hydroxide, (2) contacting said mixture with an oxidizing gas at a temperature of from about 250 F. to about 600 F., to effect oxidation of said oil and reaction of said metal hydroxide with the oxidized oil, (3) continuing said oxidation for a time sufficient to efiiect the reaction of at least about 5%, but not more than about 55%, of said metal hydroxide and (4) subjecting the resulting reaction mixture to filtration to separate the metalcontaining oxidized oil product.

3. A process for preparing a calcium-containing oxidized oil product which comprises (1) forming a mixture comprising (a) a petroleum oil having a molecular weight of from about 300 to about 1000 and (b) from about 2% to about 25 based on the weight of said oil, of calcium hydroxide, (2) contacting said mixture with an oxidizing gas at a temperature of from about 250 F.

4. A process for preparing a barium-containing oxidized oil product which comprises (1) forming a mixture comprising (a) a petroleum oil having a molecular weight of from about 300 to about 1000 and (b) from about 2% to about 25%, based on the weight of said oil, of barium hydroxide, (2) contacting said mixture with an oxiding gas at a temperature of from about 250 F. to about 600 F., to effect oxidation of said oil and reaction of said barium hydroxide with the oxidized oil, (3) continuing said oxidation for a time sufiicient to etfect the reaction of at least about 5%, but not more than about 55%, of said barium hydroxide and (4) subjecting the resulting reaction mixture to filtration to separate the bariumcontaining oxidized oil product.

References Cited in the file of this patent UNITED STATES PATENTS 2,008,490 Dietrich et al. July 16, 1935 2,020,648 Hyman Nov. 12, 1935 2,274,057 Gerlicher Feb. 24, 1942 2,335,733 Burwell Nov. 30, 1943 2,389,090 Shields Nov. 13, 1945 2,417,428 McLennan Mar. 18, 1947 2,417,432 McLennan Mar. 18, 1947 2,430,864 Farkas et al. Nov. 18, 1947 2,447,794 Brewer Aug. 24, 1948 2,533,620 Polly Dec. 12, 1950 2,616,904 Assefif et al. Nov. 4, 1952 2,616,906 Assetf et al. Nov. 4, 1952 2,682,553 Kirk et a1 June 29, 1954 2,695,910 Asseff et al Nov. 30, 1954 2,779,737 Kroft et al. Jan. 29, 1957 FOREIGN PATENTS 386,715 Great Britain Jan. 26, 1933

Claims (1)

1. A PROCESS FOR PREPARING A METAL-CONTAINING OXIDIZED OIL PRODUCT WHICH COMPRISES (1) FORMING A MIXTURE COMPRISING (A) A PETROLEUM OIL HAVING A MOLECULAR WEIGHT OF FROM ABOUT 25%, BASED ON THE WEIGHT OF SAID OIL,OF A HYTO ABOUT 25%, BASED ON THE WEIGHT OF SAID OIL, OF A HYDROXIDE OF A METAL OF GROUP 11 OF THE PERIODIC TABLE OF THE ELEMENTS, (2) CONTACTING SAID MIXTURE WITH AN OXIDIZING GAS AT A TEMPERATURE OF FROM ABOUT 250*F. TO ABOUT 600* F., TO EFFECT OXIDATION OF SAID OIL AND REACTION OF SAID METAL HYDROXIDE WITH THE OXIDIZED OIL, (3) CONTINUING SAID OXIDATION FOR A TIME SUFFICIENT TO EFFECT THE REACTION OF AT LEAST ABOUT 5%, BUT NOT MORE THAN ABOUT 55%, OF SAID METAL HYDROXIDE AND (4) SUBJECTING THE RESULTING REACTION MIXTURE TO FILTRATION TO SEPERATE THE METAL-CONTAINING OXIDIZED OIL PRODUCT.