US 2305034 A
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Description (OCR text may contain errors)
p it a i gem,
den. n. i
veiopment Company, a
both, a a .1
u n M corporation Nu piication new 20, 1939,
The present invention relates to addition ants which bit the emulation of petroleum oils and more specifically to compounded lubria such addition agents. been proposed to use as addition agents :5 oxidation resisting qualities of eral oils cc t basic organic nitrogen comwrtl .by having a heterocylic ature con w a: nitrogen. Compounds of l a .11 in petroleum products which we been heated to distillation temperatures. M e these compo when used alone do inhibit oxidation to a certain extent, it has been found that considerably greater oxidation reaist mwer is conferred upon an oil when the elent sulfur is in some manner added to the oil with the nitrogen base.
addition of sulfur may be accomplished in various ways. One way is to sulfurize the nitrogen base directly, as, for example, by heating the base with sulfur, or by treating the base with sulfur dichloride in a suitable solution. The suliurized nitrogen base is then added to the mineral oil.
Another and somewhat more efiective method of adding sulfur to the nitrogen base antioxidant is to add to the oil, along with the base, a sulfura. 1.1 organic compound, preferably one which is itself a mineral oil oxidation inhibitor. The a. 1.: er in which the base and the sulfur or suifur-containing organic compound cooperate to give superior antioxidant eflects is not understood; but it has been found as'a'matter of experience that an oil treated in the manner described has considerably greater oxidation re- Cdt m p113 can M It lair:
sisting power than is indicated by the summation oi the known effects of the two ingredients when used separately. For example, a given weight of a mixture of approximately equal parts of a nitrogen base extracted from petroleum anda sulfurized polymer of isobutylene will give a much greater antioxidant eflect in an oil than an equal weight ofeither one of the materials alone.
Petroleum oils of all boiling point ranges are susceptible to improvement in oxygen resisting characteristics by the use of the addition agents herein described. These include kerosenes, Diesel .oiis,'transformer oils, lubricating oils and the like; but the invention is of particluar value in the production of lubricating oils which resist oxidation at normal internal combustion engine temperatures, and in the preparation of lubrieating greases containing mineral oils.
The nitrogen base compound which is employed as the basic addition agent may be any organic compound of base characteristics having a heterocylic ring structure containing nitrogen. Compounds of this type include, as examples, quinoline or acridine', or the alkyl or aryl derivatives of these compounds, or of pyridine. More especially preferred are the naphthenic bases, 1. e., those containing a hydroaromatic ring with an atom of nitrogen in such ring. Such compounds include substances of the type of alkylated piperidine, or the more complex basic materials obtained from petroleum distillates. It is desirable to employ compounds having boiling points above 300 F. at atmospheric pressure, and in the case of lubricating oil blends the addition agent should ordinarily have a boiling point above 350 F. Y
Convenient and economical sources of the preferred nitrogen bases of the present invention are the distillates obtained in the rectification of petroleum or shale oil. The asphaltic petroleums of California are particularly rich in nitrogen compounds, having a nitrogen content in the neighborhood of 1%. It has been found, however, that nitrogen bases are not contained in the crude oils, but are formed on heating the crude oils to the temperatures encountered in distillation processes, i. e., temperatures varying from 215 F. to 740 F. Cracking temperatures are less favorable, but do generate basic nitrogen compounds to some extent. Naphthenic bases obtained from California petroleum are predominantly of hydroaromatic character, but contain also a smaller percentage of aromatic bases. The compounds present have a varying and complex structure, but they consist only of carbon, hydrogen and nitrogen, the nitrogen being present in a heterocyclic ring,
The nitrogen bases may be separated from the oils by extraction with agents such as liquid sulfur dioxide, hydrochloric acid or sulfuric acid. By one convenient method of preparing the bases, a kerosene fraction obtained by the fractional distillation of a California asphaltic crude oil is extracted at about -7 C. with liquid sulfur dioxide. The mixture so'obtained is heated to about 38 C. under pounds pressure to evap orate off the excess sulfur dioxide, cooled and extracted with cold water to obtain an aqueous solution of acid suliites of nitrogen bases. The aqueous solution is further heated to remove as much sulfur dioxide as possible, the remaining sulfur dioxide being removedin a rectifying column, and an aqueous solution of sodium hyv thiophosphites, e.
oily layer and are removed in a separator and fractionally distilled to obtain a crude mixture of nitrogen bases. which may, if desired, be redistilled under high vacuum to secure pure narrow enter The sulfur-bearing antioxidants which are added to the petroleum oils, in addition to the Other suitable antioxidants are those sulfur;-
' ized oils obtained by heating fatty or mineral oils in the presence ofsulfur or sulfurizing agents, such as sulfur chloride, according to well known means.
Certain hydrocarbons, specifically polymers of low molecular weight olefins, particularly those having less than six carbon atoms, such as ethylene, propylene, butylenes and amylenes, are superior materials for sulfurization, in that the sulfurizatlon may be accomplished with very little cracking or polymerization, and without the production of darkly colored or otherwise obiectlonable constituents. Of these materials particularly satisfactory are the polymers of isobutylene and isoamylene in that these materials instead of cracking merely depolymerize to a certain extent during the sulfurizatlon treatment and therefore give rise to cleaner and more desirable products. Materials of this kind are therefore especially suited for blendingain lubricating oils and aiding in the inhibition of autoxidation.
The polymers which are disclosed above, and particularly the polymers of isoolefins, boil above 100 0., and preferably from about 150 to about 275 C. These materials may be made by polymerization of various oleflns or mixed oleflns, using catalysts such as sulfuric or phosphoric acid, aluminum chloride, zinc chloride, boron fluoride, or other similar active halide catalysts of the Friedel-Crafts type. ,In addition to these, various siliceous catalysts may also be used, such as fullers earth or clays, especially clays activated by treatment with mineral acids, such as sulfuric, phosphoric, hydrochloric or hydrofluorlc acids. Copolymers, also suitable for use in this invention, are forme y the polymerization of mixtures of ole'flns, referably an isoolefin, such as isobutylene, with the other olefins, such as normal propenes, butenes or pentenes of the same or a'diderent number of carbon atoms per molecule. The particular methods of producing the polymers and copolymers are well known and form no part of the present invention.
The present invention inculdes the use, as one of the addition agents which aid in the lowering of the oxidizing tendencies of petroleum oils, of the sulfurized products of the above described polymers. A suitable method for conducting the sulfurization is by heating the polymer or mixture of polymers with free sulfur at an elevated temperature and maintaining the temperature for a prolonged period. sulfurizaticn begins at asoaoaa about C. and is quite vigorous within the range from 200 to 250 C. The time of heating is governed by the temperature, lower tempera tures requiring a longer time, but ordinarily it should not be in'excess of 15 minutes at the upper end of the temperature range given above, and the preferred temperature range depends upon the boiling point of the reactants, and usually a temperature of 180 to 250 C. is desirable. The sulfur combines with the hydrocarbon polymer quite readily with an evolution of hydrogen sulfide.
The product produced above may be blown to eliminate hydrogen sulfide and washed and low boiling constituents may be evaporated or distilled 0d .with steam. In many cases a small amount of sulfur is present which has not reacted, and this'may be separated by filtration or otherwise, and after this is done the filtrate is stable and sulfur does not precipitate or settle out.
The polymers described above may also be sulfurized by other suitable methods; for example, they may be heated with sulfur halides, such as sulfur monochloride or sulfur dichloride. The resulting sulfurized polymer will contain small amounts of chlorine, and may be used in this form in lubricating compositions in which the halide is not objectionable. The sulfurized polymer may also be refined with alcoholic alkali to remove the halide.
Another method of preparing the sulfurized polymer oil is to heat-the polymer with sulfur to 250 C. for between 15 and 20 minutes in the presence of metallic oxides, especially zinc oxide, or with such metallic oxides in admixture with alkyl phenol sulfides, such as tertiary amyl phenol sulfide or disulfide, or compounds which are known to exert an accelerating influence upon the vulcanization of rubber hydrocarbons. Products so obtained are refined by treatment previously mentioned in connection with the preparation of the materials according to other procedures. .The advantages of this method of preparation are thatless sulfur is lost as hydrogen sulfide, and the time and temperature of the reaction are appreciably reduced.
A particularly valuable application of the present invention is' the use of the sulfurized oleflns with the nitrogen bases in lubricating oil compositions. A feature of the blending characteristics of the sulfurized polymer oil is that it causes little impairment of color or cast. As a matter of fact, the addition of the sulfurized olefin polymer produces a very desirable red color and may be used as a lubricating oil dye. This color efiect may be obtained in the presence of nitrogen bases which are also added to the lubricating oils in accordance with the present invention, since mproperly refined nitrogen base material will impart little or no color to the oil when used in small quantities as antioxidant. This is an advantage over sulfurized mineral oils which have been,previously employed as lubricating oil addition agents in that such materials cause some depreciation incolor when blended with lubricat- 11 3 oil stocks.
In accordance with the preferred method of carrying out the present invention, a compoimded oil is obtained by adding small quantities of both asulfur-bearing antioxidant andnitrogen bases to the hydrocarbon oil. The eflectiveness of the antioxidants is not impaired by the presence in the oil of naturally occurring sulfur or nitrogen.
to quantities,,it has been found preferable to i u ploy such an amount of sulfur-bearing antiomdaat as will provide from about 0.0075 to about 0.10%, and more preferably, especially in the cases where a sulfurized polymer oil is used, from 0.0075% to 0.015%, of sulfurin the form of a combination in the antioxidant compound in the finished oil. The sulfur so combined is not to be confused with the sulfur naturally present in the lubricating oil. In'other words, when an antioxidant containing about 10% of sulfur is used, such an antioxidant should be added to an oil in quantities varying from about 0.075% to about 1.0%. The nitrogen bases are preferably added in quantities varyinsfrom about 0.10% to about 1% or even up to 5% of the oil, a more preferred range being from 0.10% to- 025%. Where sulfurized nitrogen bases are added as the sole antioxidant, these are likewise preferably added in quantities from about 0.10% to about 1%. or even up to 5%.
It has been found that the addition agents of this invention do not have any detrimental effects on the physical character of the lubricating oil or other mineral oil to which they are added, such as viscosity. gravity and flash point, or on the amount of carbon residue formed on prolonged use of the oil. The present materials may be used as the sole blending agents or they may be added. as in the case of a lubricant. with other ingredients which serve other purposes. They are, for example, useful agents when added to leaded lubricating oils, that is to say lubricants containing lead oleate, lead naphthenate, lead sulfonate or other heavy metal soaps. They also may be added along with oiliness agents, pour depressants, lubricating oil dyes or agents to give fluorescence. They may be used in conjunction with any other antioxidants or with thickeners, sludge dispersers and the like. In the case of Diesel fuels, there may be present ignition promoters and other ingredients common to motor fuels.
As has been stated above, an efiective antioxidant for oils, superior to nitrogen bases alone, may be prepared by s a w in the nitrogen bases directly. The sulfurized products may be obtained, for example, by heating the bases with sulfur, or by treating the bases with sulfur dichloride in a suitable solution. The sulfurized products may be purified by treatment with sodium sulfide solution to improve the color and to render comparatively non-corrosive. Such purification lowers the sulfur content somewt. The final product lowers the oxygen absorption rate of a lubricating oil with which it is blended to a greater extent than the unsulfurized nitrogen base, but not as much as does a combition of a sulfur-bearing antioxidant, such as a sulfurized polymer oil, and a nitrogen base, which is the preferred embodiment of the present invention.
The value of the antioxidants of the present invention when used in lubricating oil blends have been determined by a standard oxygen absorption test. This test is used for the most viii in jud ing the oxidation susceptibility of a lubricating oil at enmne operation temperatures.
a wn amount of oxygen is bubbled through cc. of the lubricating oil maintained at 200 C. The oxygen is continuously recycled. At the asoaosi end of successive 15 minute periods the amount I of oxygen absorbed by 10 cc. of an oil per 15 minute intervals at 200 C.
In the following examples, methods of preparing a sulfurized' polymer oil, nitrogen bases and blends of these with lubricating oils are shown, together with data on the oxidation rates of oils containing such materials:
Example 1 An isobutylene polymer having a viscosity of 84 seconds Saybolt at 210 F. and open cup flash point of 305 F. was caused to react with 15% of sulfur by heating to 250 C. for about 15 minutes in the presence of 1% of zinc oxide and 1% of Pip-Pip" (piperidinium-pentamethylene-dithiocarbamate), a commercial vulcanization accelerator manufactured by the Monsanto Chemical Company. The product obtained by this method had asulfur content of 6.45%
Example 2 An oxygen absorption test, conducted according to the standard procedure described above, was made on a blend consisting of a refined mineral lubricating oil of 20 S. A. 8. grade to which had been added 0.125% by weight of a sulfurized polymer oil prepared according to Example 1 and 0.125% of a nitrogen base product prepared by the extraction of a'kerosene fraction of 8. California crude petroleum, the base used being. a fraction boiling at -165 C. at 4 mm. pressure and ,containing about 4.5% nitrogen. Corresponding oxygen absorption tests 'were made on a sample-of the unblended base oil, alsoon samples of this oil ntaining the same nitrogen base material alone, 0 the sulfurized polymer oil alone. and a sample blended with a s'ulfurized nitrogen base containingl.66% of sulfur. Thedata of the following table show the number'of cubic centimeters of oxygen absorbed by 10 cc. samples of the oils for several successive 15 minute intervals at 200 C.
The present invention is not to be considered as limited in any way by any of the herein described examples, which are given by way of illustration only, but is to be limited solely by the terms of the following claims in which it is desired to claim all novelty inherent in the invention.
1. An improved mineral oil composition comprising a petroleum oil fraction, a small proportion, not more than 5%, of an organic base having a heterocyclic structure containing nitro- 1 said organic base being an antioxidant for petroleum oils, and a1small proportion, not greater than 0.1%, of the element sulfur, said sulfur being present in an organic compound which is an antiomdantfor petroleum oils.
2. An improved mineral oilcomposition com prising a petroleum oil fraction, a small proportion, not more than 5%, of an organic heterocyclic nitrogen base extracted from a petroleum distillate. nitrogw dant, a proporti of a organic antiondant, the cunt b w to produce a conwntration of not more 0.1% of sulfur in the form of the said sulfurantiomdant.
3. an improved mineral oil composition com- 7 aseaeg mg a heterocyclic hydroaromatic ring structure con nitrogen. said organic base an antioxidant, and a small proportion of a sulfurized polymer of an olefin. sumcient to produce a concentration of not more than 0.1% of sulfur in the form of the sulfurized polymer.
5. An improved mineral oil composition comprising a petroleum oil fraction, a small proportion, not more than 5%, of an organic heteclic nitrogen base extracted from a mtroleum distillate, said nitrogen being an antioxidant. and a small proportion of a sulfurized polymer of an olefin, cient to produce a concentration of not more than 0.1% of sulfur in the form of the sulfurized polymer.
6. An improved lubricant comprising a hydrocarbon lubricating oil,'a small proportion, not more than 5%, of an organic nitrogen base having a heterocyclic structure and having men extracted from a petroleum distillate, said nitrogen base being an antiomdant, and a small proportion of a sulfurized polymer of an olefin, sumcientto produce a concentration of not more than 0.1% of sulfur in the form of the sulfurizei polymer. v
7. an improved lubricant comprising a hydrocarbon lubricating oil, a proportion, not more than 5%, of an organic nitrogen base having a heterocyclic structure and having extracted from a petroleum distillate, said nitrogen base being an antioxidant, and a small proportion of a sulfurized polymer of an olefin has less than six carbon atoms, cient to produce a concentration of not more than 0.1% of sulfur in the form of the sulfurined er.
8. an improved lubricant comp a hydrocarbon lubricating oil, a small proportion, not more than 5%, of an organic he a gen base extracted from a California asphaltic base crude petroleum oil, d nitrogen base being an ant, a ens proportion of a sulfurised polymer of an 01 having less than six carbon a deriv by suliurizing an olefin polymer having a point above 100 0., the amount a: cient. to produce a concentration of not more 0.1% of sulfur in the form of the sulf polymer.
. 9. An improved lubricant comprising a hydrocarbon lubricating oil, a small proportion, not more than 5%, of an organic heterocyclic nitrogen base extracted from a irerosene fraction of a California asphaltic base crude petroleum oil, said nitrogen base being an antioxidant, and a proportion of a sulfurized polymer of isobutylwe,
l cient to produce a concenn'ation of not more 7s '10. v lcant carbon lubs'im oil, a
a t $95, Of M1 he ob a by a tion of a Dalifornia tic oil with sulfur do,
M Ma m swims w aw polymer of iaobuwlene,
m ofmtmogg 1 clmt to produ g 0.1% of sulfurin the form of the mer.
11. an improvlut W a carbon iubriw oil, a more5%.ofaonofano rqcycflc a men mm l l a mew W a 1m ting a kerosene fraction of a o ascrude mtroleum oil with if diomde, said fraction of hi at having antiomdant promrties and he a dis tion of smut 1st" to about 165 C. at oters p and a small proportion a polymer of isobutylene derived a w anisobutylene polymer having a point H produce a concentration of not more 0.1% of sulfur in the form of the s polymer.
12. an improved mineral'oil composition comp a petroleum oil fraction, 0.10% to 1% by weight of an organic heterocyclic nitrogm b extracted from a' petroleum distillate, said nitrogen b being an antioxidant, and an amount of a sulfur-bearing organic antioxidant cient to give the component oil 0.il0'l5% to 0.10% by weight of sulfur combined in said antioxidant.
13. An improved lubricant comprising a hydro- "wrmn lubricating oil, 0.10% to 1% by weight of an no heterocyclic nitrogen base material ob by extracting a lrer fraction of a California asphaltic base crude petroleum oil with liquid sulfur dioxide, said nitrogen base material having antioxidant promrties, and an amount of a w g a r polymer of isobutylene to give the compounded oil 0.0075% to 0.10% by wht of sulfur combined with olefin polymer, said sulfurized polymer being formed by a ing an isobutylene polymer having a be point from to 275 C.
is. An improved lubricant comp a hydrocarbon lubricating ;oil, 0.10% to 0.25% by yvht of a fraction of an organic heterocyciic en material obtained by extracting a i e fraction of a California asphaltic crude mtroleum oil with liquid sulfur dioxide, said fraction of nitrogen material having antiomdant properties and having a distillation range about Mb" to smut C. at e millimeters presand an cunt of a sulf par of imbuiy cient to mve the compound oil 0.0M5% to 0.015% by Weight of sulfur with 1- polymer, sulf polymer formed by sulf an isobutylene a having a boiling point from W0 to 375 c.
Ill-ill powasoaoaa by suliurizing an antioxidant consisting of an organic heterocyclic nitrogen base extracted from a petroleum distillate, the amount being sumcient to produce a concentration of not more than 0.1 7 of sulfur in the form of the sulfurized nitrogen base.
17. An improved lubricating oil composition comprising a petroleum lubricating oil fraction, a small proportion, not more than 5%, of an organic base containing carbon, hydrogen and nitrogen, but substantially free from halogen, and having a heterocyclic structure contalningnltrogen, said organic base being-an antioxidant for petroleum oils, and a small proportion, not greater than 0.1%, of the element sulfur, said sulfur 15 being present in an organic compound which is an antioxidant for petroleum oils.
18. .An improved lubricant comprising a hydrocarbonlubricating oil and a small proportion, not more .than 5%, of a material obtained by sulfurizing an antioxidant consisting of an organic heterocyclic nitrogen base extracted from a kerosene fraction of a California asphaltic base crude petroleum oil with liquid sulfur dioxide, the amount of the sulfurized nitrogen base present being sumcient to produce a concentration of not more than 0.1% of sulfur in the form of such sulfurlzed iiitrogen base.
BEN W. GEDDES.