US2327158A - Process for preparing lubricating oils - Google Patents

Description

Aug. 17, 1943. G. H. VON FUCHS 2,327,158

PROCESS FOR PREPARING LUBRICATING OILS Filed March 3, 1941 nuhzs I I o I 2.5 5 1.5 10 Conczmmfion (KW) of Added Resins in Ftnon Bknd lnvznforsrGzorqz Hugo von Fuchs Hqman Diamon Patented Aug. 17, 1943 George Hugo von Fuchs and Hyman Diamond,

Alton, Ill., assignors to Shell Development Com- Dany, San Francisco,-

Delaware Calili, .a corporation of Application March 3, 1941; Serial No. 381,530

9 Claims.

This invention relates to a new method for processing mineral oils to' produce lubricating oils of high stability, and more-particularly deals with a method wherein lubricating oil stocks are fractionated and reblended according to a novel procedure. a v

The main purpose of this invention is to fractionate mineral lubricating oil stocks ina manher so that onreblending the several fractions, not only the viscosity of the blend can be controlled but within limits its oxidation stability as well,

It is common practice in the manufacture of lubricating oils to divide available lubricating oil stocks by. fractional distillation into. so-called neutral oils and bright stocks, i. e., residual oils, and thereafter producing oils of different viscosities by blending two or more of these frac-.

tions with each other in the necessary proportions to obtain whatever viscosity may be desirable. Thus relatively light oils as the SAE 10 and 2D grades normally comprisepredominating amounts or consist of neutral oils, while the heavier grades contain as a rule more bright stock. 1

Now we have discovered thatlubricating oils of different viscosities produced by blending given neutrals and bright stocks in different proportions have different oxidation stabilities. In the case of well-refined oils We have. found that as a rule intermediate-viscosity grades c'ontain-,

ing substantial portion of both neutrals and bright stocks, have the highest stabilities. We have concluded that the reasonfor this peculiar behavior is caused by a component which is normally contained in bright stocks in varyina amounts, namely, the bright stock resins. Bright stock resins as herein defined arehigh-boiling normal constituents of bright stocks. They are recognized by their ability of being adsorbed by silica gel and other acid solid adsorbents but are less readily adsorbed by alkaline or non-acidic adsorbents such as fullers earth, bauxite, zeolites, etc.

It ha been known for some time that highboiling mineral oils contain resins, and that an approximate'analytical method for determining their content has been described by Kalichevsky and Fulton in National Petroleum News. volume 23, Number 51, pages 33-6, 1931. It was heretofore generally believed that these resins form a more or less undesirable portion of lubricating oil being responsible for high carbon residue of lubricating oils. Therefore, considerable efforts have been expended in the past to find methods for deresining lubricating oils, in the hope of thereby reducing carbon residues. However, ap-

parently it remainedunnoticed that these resins have a verylstrong influence on the oxidation stabilities of the oils, which influence may be. beneficial or detrimental depending upon the concentration of the resins in the oil and on the, susceptibility of the particular oil to. the resins.

We have definitely established that any wellrefined mineral lubricating oil should contain a certain amount of resins for maximum stability.

What this'amount should be cannotbe stated; in general terms because of several diiiiculties.

In the first place, it appears that the group of. substances known as resins is-rather complex and apparently contains components some of which are efiective in, smaller concentrations than others. Moreover, in the usual processes of isolating or concentrating resins, resin concene trates are obtained which besides the resinsnor mally contain harmful impurities. These impurities actually may cause a decrease in the stability of blends containing otherwise an optimum quantity of the beneficial resins. Again different oils have vastly different susceptibili ties towards .the resins' Thus some oils may tolerate or necessitate relatively large amounts of resins, While others reach their maximum. stabilities at much lower concentrations; fur- V ther difliculty, resides in the inaccuracy'of the analytical method, which not only fails to give close checks between duplicate determinations, but also fail to distinguish. between the useful resins and certain inert or harmful impurities. which normally are associated with the former.

In View of the above, the only practical way of determining the optimum concentration of in any one oil isto add successively larger amounts'cf resins to different samplesof this oil and then determine the oxidation stability of the several blends so obtained by any of the accepted oxidation methods, preferably in the presence of iron. against the amount of resins or resin concentrate. added, the optimum blend is theneasily estab lished. v

Havingorice recognized that the presence of resins in limited amounts in lubricating oilshas definite advantages, our procedure of controlling both the viscosities and. the stabilities of lubrieating oils, resolves itself into producing besidesthe conventional neutral oils at least twohigh viscosity stocks, one of which i a bright stock, of low resin content and. the other is a resin con centrate. Our improved-oils are then produced;

By plotting the stabilities so obtained normally produced by blending neutral oil, lowresin content bright stock and resin concentrate in suitable proportions.

While, as previously pointed out, the most deirable amount of resins to .be added cannot be predicted but must be established experimentally for lubricating oils from different sources, .we

find that the optimum resin contents normally vary between about 1% to 10%, and more often than not between about 3% and "7%.

Bright stocks of low resin content and resin concentrates are most readily obtained by treating conventional bright stocks such as properly deasphalted '(and de'waxed, if necessary) heavy mineral oil distillation residues with normally gaseous hydrocarbons at elevated pressures, preferably at pressures and temperatures near or above the critical conditions of these light hydrocarbons.

critical conditions. v

The operation 'of deresining is well known in the art of "lubricating oil manufacture. ,Two fractions are thereby obtained, a bright stock of low resin content and a resin concentrate. As a rule, both the deresined bright stock and the"resin concentrate have lower oxidation stabilitie's than the bright stock fromwhich they are derived.

Bright stocks from which the resin concentrate's are obtainable may be produced by any c'onventionalmethod of manufacture, such as topping a crude petroleum oil containing lubricating oil stock to produce a residue having a suitable viscosity and removing asphalts (and waxes, if necessary) as by propane precipita-' tion or other known means. Vacuum-distilled heavy oils normally yield relatively small amounts of resins, In fact the natural resin content of such oils is normally lower than is required for optimum stability. They may, however, be used in place of the low-resin bright stock in making up blends.

The effectiveness of the resins as oxidation stabiliz rs may be considerably improved by removing therefrom certain impurities which are normally associated therewith. We have discovered that harmful impurities can effectively be separated from the desirable resins by treating the precipitated resin mixture or the resin concentrate with a neutral or alkaline-reacting adsorbent such as bauxite, brucite, basic permutites, naturally 'a'ctive decolorizing clays as Florida clay and Attapulgus clay, fullers earth, etc. These adsorbents peculiarly enough are selective for many of the impurities normally associated with the resins, but do not adsorb.

to any great extent the resins themselves. Therefore in our preferred procedure we treat the resin concentrate preferably in solution in a low-boiling hydrocarbon oil such as naphtha,

fled by acid treatment. Moreover, because'resins' These conditions are known as paraare susceptible to attack by sulfuric acid, it is not desirable to treat bright stocks from which resins are to be separated, with excessive amounts of sulfuric acid. If for some reason severe acid treatment of the bright stock is desired, this should be carried out after the resins have been separated to avoid their being destroyed.

In order to illustrate our invention, reference is had to the attached drawing which represents a graph wherein concentration of resins in vari- "ous lubricating oils of about the same viscosities is plotted against oxidation stability as measured by the time required to absorb 1800 cc. of oxygen per 100 grams of oil by contacting the oil under standardized conditions with oxygen in the presence of iron (temperature 313 F., 5 sq. cm. exposed iron surface per gram of oil, oxygen pressure 760 mm. Hg). The oils were prepared by blending a (1) resin-free bright stock, (2) a neutral oil and (3) resins, to produce mixtures containing 50% neutral and 50% mixed bright stock and resins, the ratio of bright stock to resins being different in the several mixtures. ,As will be seen from the drawing, a maximum stability is indicated at a resin con tent of about 5%.

Concerning the effects of impurities contained 7 in resins, the following data are significant: A

comprising producing at least one low resin con tent mineral lubricating oil and a petroleum 7 resin concentrate, purifying the latter without materially altering the resin content, and blendme said low resin content oil with the purified resin concentrate, in an approximate proportion to produce a blend containing between 3 and '7 resin and having about maximum oxidation stability.

2. Process for manufacturing lubricating oils comprising producing at least one low resin content mineral oil and a petroleum resin concentrate, contacting the latter with. a basic reacting mineral adsorbent whereby acidic impurities are adsorbed without'materially altering the resin content, and blending said low resin content oil with the contacted resin concentrate in an approximate proportion to produce a blend containing between 3 and 7% resin and having about maximum oxidation stability.

3. The process of claim 2 wherein said adsorbent is bauxite.

4. Process for manufacturing lubricating oil comprising producing at least one low resin -content mineral lubricating oil and a petroleum resin concentrate, separately subjecting said low I resin content oil to a refining treatment to improve its oxidation stability, contacting said resin concentrate with a basic reacting mineral adsorbent whereby acidic impurities are adsorbed wlthoutmaterially altering the resin content,

7 and blending the treated low resin oil with the contacted resin concentrate in an approximate proportion to produce a blend containing between 3 and 7% resin and having about maxi- 7. Process for manufacturing lubricating oil comprising subjecting a deasphalted residual lubricating oil stock of low wax content to a deresining treatment to produce a bright stock of lower resin content and a resin concentrate,

purifying the latter without materially altering the resin content, and blending said bright stock with at least one neutral oil and said resin concentrate in approximate proportions to produce the amount of resin in said blend being between 3 and 7%.

8. The process of claim 7 wherein said deresining treatment comprises treating the residual stock with a normally gaseous hydrocarbon under para-critical conditions of said hydrocarbon.

9. Process for manufacturing lubricating oils comprising subjecting a deasphalted residual lubricating stock of low wax content to a deresining treatment to produce a bright stock of low resin content and a resin concentrate, separately subjecting said bright stock to a refining treatment capable of improving its oxidation stabilitmcontacting said resin concentrate with a basic reacting mineral adsorbent whereby acidic impurities are adsorbed without materially altering the resin content, and blending the resulting refined low resin bright stock with at least one neutral oil and with the contacted resin concentrate in approximate proportions to produce a blend containing 3 and 7% resin and having about maximum oxidation stability.

GEORGE HUGO VON FUCHS. HYMAN DIAMOND.

a blend of about maximum oxidation resistance

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