US3725280A - Mixtures of mono-n-alkylbenzenes and di-n-alkylbenzenes - Google Patents

Abstract

LUBRICANT OILS COMPRISING 5-30 PARTS BY VOOLUME OF MONO-N-ALKYLBENZENES AND 70-95 PARTS BY VOLUME OF DI-N-ALKYLBENZENES.

Description

United States Patent Office 3,725,280 Patented Apr. 3, 1973 No Drawing. Continuation of abandoned application Ser.

No. 725,908, May 1, 1968. This application May 10, 1971, Ser. No. 148,266

Int. Cl. C10m 1/16 U.S. Cl. 252--59 13 Claims ABSTRACT OF THE DISCLOSURE Lubricant oils comprising -30 parts by volume of mono-n-alkylbenzenes and 70-95 parts by volume of di-n-alkylbenzenes.

CROSS-REFERENCE STATEMENT This application is a streamlined continuation of abandoned application Ser. No. 725,908, filed May 1, 1968.

BACKGROUND The present invention relates to synthetic hydrocarbon compositions having properties which render them particularly useful as lubricants in extremely low temperature operations.

Various petroleum fractions have been used as lubricants for many years. While the petroleum-derived lubricants have been satisfactory for most uses, there are fields of use, as for example, jet engine lubricants and arctic oils, wherein the requirements render the conventional petroleum-derived lubricants either unsatisfactory or of marginal utility. In an attempt to solve this problem synthetic lubricants (for example, diesters) have been developed having improved properties, particularly improved viscosity and pour point properties. Unfortunately, however, the synthetic lubricants of the prior art have been relatively expensive. It is thus apparent that it would be highly desirable to develop an inexpensive synthetic lubricant having very good viscosity, pour point and flash point properties.

PRIOR ART The following US. patents are believed to be the most pertinent prior art.

US. 3,288,716, to Becraft and Durr, teaches a synthetic hydrocarbon lubricant having good low temperature viscosity, excellent pour point and flash point properties. The composition of this patent contains the following materials: dialkylbenzenes; diphenylalkanes; alkyl tetralins, indanes, and other condensed alkyl aromatics; and, monoalkylbenzenes. The patent teaches (1) preferably, the diphenylalkanes are present in amounts of about 5 parts to about 50 parts by volume and (2) the monoalkylbenzenes are not desirable.

U.S. 3,173,965, to Pappas and Kant, teaches dialkylbenzenes as lubricants. The patent does not recognize that addition of monoalkylbenzenes to dialkylbenzenes can improve the physical properties of the product mixture. The patent teaches that the dialkylbenzenes are prepared by: (1) alkylating benzene with an alkylating agent and (2) alkylating the resulting monoalklybenzene with an alkylating agent. The patent further teaches that the alkylating agent can be a-olefins, monohydroxylated paraflins, or monohalogenated paraffins, and, in this connection states: Alkylation as used herein means a process for introducing alkyl substituents onto a benzene residue in which the linkage is through the a-carbon atom of the alkyl substituent.

It may be well to state at this: time that the hydrocarbon compositions of our invention are restricted to di-n-alkylbenzenes derived by disproportionation of monon-alkylbenzenes. We have found that products prepared by disproportionation give the best compromise of low temperature pour point and low temperature viscosity in the product. By contrast, use of alkylation to introduce the second alkyl group onto the benzene ring improves the viscosity property but deteriorates the pour point.

BRIEF SUMMARY OF THE INVENTION Broadly stated, our invention relates to synthetic hydrocarbon lubricating compositions consisting essentially of from about to about parts by volume of a disproportionated product derived from mono-n-alkylbenzenes, which are predominantly di-n-alkylbenzenes, and from about 5 to about 30 parts by volume mono-n-alkylbenzenes, the alkyl groups of said mono-n-alkylbenzenes and said di-n-alkylbenzenes containing from 10 to 15 carbon atoms, preferably from 12 to 14 carbon atoms, said compositions containing less than 4.5 percent, preferably less than 2 percent, by volume, diphenylalkanes.

The disproportionated products, which are derived from mono-n-alkylbenzenes, are sometimes referred to simply as di-n-alkylbenzenes, hereinafter.

In one aspect our invention relates to a method of lubrication employing as the lubricant the synthetic hydrocarbon compositions described in the foregoing. In particular this aspect relates to the lubrication of machinery and turbojet engines employing the synthetic hydrocarbon composition described in the foregoing.

It should be emphasized that the synthetic hydrocarbon lubricating compositions described in the foregoing in addition to having a specific chemical composition must meet certain specific physical properties described hereinafter.

DETAILED DESCRIPTION Description of desired physical properties MIL-L-IOZQSA SPECIFICATION S Requirement limits Physical property Minimum Maximum Viscosity, kinematic, cs.:

at 210 F Pour point, F Stable pour point, F Flash point, 00 0, F-

The requirements for a grade of oil suitable for use in jet aircraft engines for type 11 service are stated in military specification, MIL-L-23699A, which is listed below.

MIIF'IIZBGQQA. SPE GIFIOATION S Requirement limits Physical property Minimum Maximum The lubricant compositions of our invention meet one or both of the specifications stated above. Due to the variation of the physical requirements of the two specifications, it is extremely difficult for a lubricant composition to meet both specifications. Some of our composi tions meet both requirements. Generally, it is better to prepare a composition which meets only one of the specifications. Some of our compositions meet a single specification as stated above. It is within the scope of our invention to provide a composition which meets either of the specifications. Knowing the specification and having our invention before him any person skilled in this art can arrive at a composition which meets either specification.

While the lubricant compositions of our invention are effective as lubricants, it is customary in this art to incorporate in the lubricant various additives, such as oxidation inhibitors, corrosion inhibitors, anti-foam agents, and viscosity index improvers. For this reason, the term lubricant composition as used herein means a base lubricant composition, and not a compounded lubricant composition.

While the physical property requirements stated in MIL- L-10295A and MIL-L-23699A define absolute limits for the fully additive-compounded lubricant, rather than the base oil, our lubricant compositions meet these requirements, within the limits defined in the foregoing.

It has been our observation that the use of additives has an adverse effect on the physical properties, particularly viscosity properties, of the compounded lubricant. For this reason, it is preferable that the base lubricant, to be used in an arctic oil, have the following viscosity properties.

Viscosity, cs.: at 210 F.: minimum, 4.10; at 40 F.: maximum, 6,500.

A lubricant composition of our invention for use as an arctic oil, suitably, meets the MIL-L-10295A specification stated previously and, preferably, has the following more stringent viscosity properties:

Viscosity, cs. at 210 F.: 4.50 minimum; at -40 F.: 6,000 maximum.

Preparation of our compositions As stated previously, the compositions of our invention consist essentially of mixtures of mono-n-alkyl-benzenes and disproportionated products which are predominantly di-n-alkylbenzenes. Prior to describing in detail these materials, We believe it may be well at this time to describe the preferred method of preparing them.

Preferably, the mixture of mono-n-alkylbenzenes is prepared by alkylating benzene with a mixture of substantially monohalogenated paraffins, containing to carbon atoms, using a Friedel-Crafts catalyst. One such method is described in detail in US. Pat. No. 3,316,294 which is made a part of this disclosure.

Briefly, US. 3,316,294 relates to a process of preparing a detergent alkylate, wherein the process comprises the following steps, broadly stated: (a) separating a fraction of substantially straight-chain (l -C hydrocarbons from a petroleum distillate substantially free of olefins and containing said straight-chain hydrocarbons together with non-straight chain hydrocarbons, (b) chlorinating said fraction to the extent whereby between about 10 and about 35 mole percent of the straight-chain hydrocarbons present are substantially only mono-chlorinated, and (c) alkylating an aromatic compound, e.g. benzene, with the chlorination product of step (b) in the presence of an alkylation catalyst.

While US. 3,316,294 concerns a process which can use C to C hydrocarbons the present invention uses, at the most, hydrocarbons containing from 10 to 15 carbon atoms. This selection of 10 to 15 carbon atoms can be made either in the initial feedstock or by fractionation of the alkylbenzene product.

The mixture of mono-n-alkylbenzenes which is used per se in our lubricant compositions, and also to prepare the disproportionated products, has the following properties:

Suitable Preferred Preparation of disproportionated product The disproportionated product is derived from the above-described mono-n-alkylbenzenes. As a starting material for the disproportionation reaction we can use the entire mono-n-alkylbenzene fraction. Also, We can distill overhead selected amounts of the mono-n-alkylbenzene and use the overhead fraction. Further, we can subject the mono-n-alkyl-benzene to fractional distillation and use selected fractions.

Process conditions for disproportionation reaction Disproportionation of the mono-n-alkylbenzenes to di-n-alkylbenzenes is conducted using a Friedel-Crafts catalyst. The term Friedel-Crafts catalyst is well understood in the art and refers, generally, to materials such as the aluminum halides, boron trifluoride, boron trichloride, antimony chlorides, stannic chloride, zinc chloride, and mercuric chloride. Preferably, the Friedel-Crafts catalyst is aluminum chloride or aluminum bromide. The more preferred catalyst is aluminum chloride, which also includes in situ prepared aluminum chloride, or, in other words, the reaction product of aluminum metal and hydrogen chloride.

In some cases it is desirable to use a proton-donor promoter with the Friedel-Crafts catalyst. Suitable promoters include any material which, when added to the catalyst, yields a proton. Preferred promoters are hydrogen chloride and water. The amount of promoter is typically about 4 weight percent based on the weight of the catalyst employed.

Preferably, the catalyst is added to the reaction mixture after the mono-n-alkylbenzenes are brought to within the correct temperature range, which will be described below. The amount of the catalyst which is used can vary from about 0.1 weight percent to about 10 weight percent based on the mono-n-alkylbenzene starting material. Preferably, the amount of catalyst is from about 0.5 weight percent to about 3 weight percent.

The disproportionation process, suitably, is conducted at a temperature of from about 20 C. to about 130 C. Since maximum yields of the di-n-alkylbenzenes are obtained at temperatures between about 75 C. and 120 C., these temperatures are preferred. The most preferred temperature is about 100 C. When this temperature is used, preferably the amount of catalyst is from about 1 to about 2 weight percent.

Following the reaction, the reaction mass is distilled in order to remove the benzene, paraflins and unreacted mono n alkylbenzenes. The desired disproportionation product is the bottoms fraction with a distillation cut point of 197 C. at 5 mm. Hg. In other words the desired product distills above 197 C. at 5 mm. Hg.

While We have described in detail the process conditions for the disproportionation reaction, the disproportionation process is not part of our invention. This process is disclosed and claimed in application Ser. No. 529,- 284, filed Feb. 23, 1966, and now abandoned.

Description of mono-n-alkylbenzenes and di-n-alkylbenzenes Preferably, the mono-n-alkylbenzenes used in our invention, have a composition which can be represented by the following formula:

where R; is a straight-chain alkyl group containing 1 to 7 carbon atoms and R is a straight-chain alkyl group containing 1 to 8 carbon atoms, with the sum of R and R being from 9 to 14.

The mono-n-alkylbenzene mixture used in the final composition has a viscosity index (100-210 F. basis) of from about 75 to about 90, and a pour point of from about 70 F. to about 115 F.

The di-n-alkylbenzenes present in the disproportionated product used in our invention have alkyl groups of the same type as the mono-n-alkylbenzenes described in the foregoing. The disproportionated product used in the final composition has a viscosity index (100210 F. basis) of from about 105 to about 120 and a pour point of from about -55 to about 70 F. The disproportionated product contains at least 55 percent by weight di-n-alkylbenzenes, preferably at least 70 percent by weight di-n-alkylbenzenes.

The lubricating compositions of our invention contain the following amounts of mono-n-alkylbenzenes and disproportionated product (in parts by volume).

USES FOR OUR COMPOSITIONS The lubricant compositions of our invention are partic ularly useful wherever a combination of low pour point (eg 65 F.) and good viscosity properties at -40 F., F and 210 F. are needed. As stated previously they are particularly useful for lubricating machinery (internal combustion engines or otherwise) in arctic climates. They are also particularly useful as jet engine lubricants. They can be used in automatic transmission fluids and in hydraulic fluids. Their properties render them useful in a wide variety of specialized lubrication problems, an example of which is the lubrication of aircraft instruments. Moreover, they can be used as base lubricants in the preparation of specialty greases.

In order to disclose the nature of the present invention still more clearly, the following illustrative examples will be given. It is to be understood that the invention is not to be limited to the specific conditions or details set forth in these examples except insofar as such limitations are specified in the appended claims.

EXAMPLE 1 This example shows the preparation of a pilot plant batch of the lubricant of our invention.

DISPROPORTIONATION Two batches of disproportionate were prepared.

RUN A The charge was an alkylate fraction prepared by the process of US. 3,316,294. The alkylate fraction had the following composition and properties:

Mono-n-alkylbenzenes: Wt. percent C10 and C11 C 12.5 C 44.3 C 32.2

Wt. Percent Dialkyltetrahydronaphthalenes 8.0 Miscellaneous compounds 1.0

Molecular weight, 260. Boiling range, at 5 mm. Hg, -197 C.

Procedure To a SOO-gallon Pfaudler vessel were charged 2375 lbs. of the above-described alkylate. While stirring and heating the alkylate to 100 C., HCl was added until the alkylate was saturated. HCl addition was then stopped. A weight of 19 lbs. of anhydrous AlCl was added to the mixture as catalyst. The reaction mass was mixed at 100 C. for 1 hour following the catalyst addition. Mixing was stopped and the reaction mass was settled for about 2 hours. Spent catalyst sludge (43 lbs.) was re moved and the remaining product was caustic washed (5% caustic) and water washed using about /2 volume of Wash solution per volume of reaction mixture. The washed product Weighed 2299 lbs. GLC (gas-liquid chromatography) analysis showed about 5.7% benzene, 5.6% paraflins, 66.2% monoalkvlbenzene and 22.5% bottoms.

RUN B Procedure The procedure was similar to that of Run A; there were used 2381 lbs. of the alkylate described in Run A and 20 lbs. AlCl catalyst. The residence time for the reaction was 1 /2 hours. There were recovered from the reaction 2329 lbs. of washed product and 44 lbs. of spent sludge. GLC analysis of the product showed 6.5% benzene, 5.9% parafiin, 63.0% monoalkylate and 24.6% bottoms.

7 FRACTIONATION The products from Runs A and B were commingled and distilled in two batches in ll-barrel stills. Combined data on the charge and the fractions are shown below.

Temp. range,

General F. (corrccted Weight Fraction identification to 760 mm. Hg) (lbs.)

Charge Crude dispropor- 4,560

tionate.

Benzene IBP(l46)-194 217 Out #2 Paratlins IBP(l46)-55O 226 Out #3 Monoalkylbenzenes. 700 2,628 Bottoms Dialkylbenzones 700 1, 452 Percent recovery 97. 9

FORMULATION BLENDING Monoalkylbenzenes (-15 fraction) 767 Dialkylbenzenes (16-66 fraction) 8991 Blend 5981 The physical properties on the blend were as follows:

Viscosity at 210 F., cs. 4.23 Viscosity at 100 F., cs. 22.75 Viscosity at 40 F., cs. 5981 Flash, COC, F. 400

Pour point, F. *75

*And still flowing.

Blend 6333P was used as a base lubricant for an automatic transmission fluid test.

Fractions from the remaining three SO-gallon still distillations were blended to obtain a second blend, which was designated -6475P. The table below shows the origin and characteristics of this blend.

Volume percent Weight, Viscosity at Fraction overhead lbs. 40 F., cs.

Cut 1, disproportionate 5, 841 Outs 2 thru 10, disproportionate 584-2 21-67 62.0 8, 394

Out 1 disproportionate 6, 077 Cuts 2 thru 10, disproportionate 584-4 21-66 97.0 8, 962

Cuts 1 thru 7, disproportionate 584-5 0-14 28- 5, 547 Cuts 8 thru 19, disproportionate 584-5 -66 180.0

Total, ca 13%- 87% 39. 29 5, 642

IMAB; DAB.

Blend 6475P'had the following physical properties:

Gravity, API 32.1 Viscosity, at 210 F., cs. 4.19 Viscosity, at 100 F., cs. 22.22 Viscosity, at -40 F., cs. 5642 Viscosity index 100 Flash point, COC, F. 400

Pour point, F. (below) 80 EXAMPLE 2 Blend 633 3P was used as a base lubricant for an automatic transmission fluid. The compounded lubricant had the following composition:

Wt. percent 6333P 92.75 Dispersant-inhibitor 1.5 Dispersant-antirust 2.0 Antiwear oxidation inhibitor 1.0 Antiwear additive 0.75 V.I. improver 2.0

The test was a standard Power Glide transmission test. Duration of the test was 300 hours. The results of the test were as follows:

Varnish l Sludge 1 1. Oil seals: Front seal flexible, no cracking.

Other seals flexible with some cracking. 2. Composition clutch plates:

A. Drive unit, normal, no chipping of composition B. Reverse unit, normal, no chipping of composition 3. Steel clutch plates:

A. Drive unit.

B. Reverse unit 4. Clutch piston-inside 5. Servo interior: A. Piston.. B. Cover Pressure regulator valve Oil screen metal side. 8. Oil pan Total rating Average 1 Best possible rating is 10.

EXAMPLE 3 Blend 6475P was used as a base lubricant for a test in a 1-H Caterpillar engine. The compounded lubricant had the following composition:

Wt. percent 6475P 91.00 Dispersant-inhibitor 1.5 Dispersant-antirust 2.5 Antiwear oxidation inhibitor 2.25 V.I. improver 2.0 Antiwear additive 0.75

The compounded lubricant was tested for 480 hours in the Caterpillar engine.

The following examples illustrate the physical properties obtained by blending different ratios of monoalkylbenzenes and dialkylbenzenes. In all examples the monoalkylbenzenes were prepared by the preferred process described herein; the dialkylbenzenes were prepared by disproportionation of monoalkylbenzenes.

EXAMPLES 4-6 Ex. 4 Ex. 5 Ex. 6

Physical properties MAB DAB blend blend blend Viscosity at- 100 F., cs- 33.0 23.10 22. 13 21. 24

210 F., cs. 5. 64 4. 39 4. 25 4. 14

Pour point, F 50 55 60 65 9 EXAMPLE 7 I This example shows the effect on 40 F. viscosity of a blend containing 25% monoalkylbenzenes and 75% dialkylbenzenes. The physical properties were as follows:

MAB DAB blend EXAMPLE 8 This example shows the properties of a blend containing 91% dialkylbenzenes and 9% monoalkylbenzenes.

The physical properties were as follows:

Physical properties MAB DAB blend Viscosity at- 40 F., cs 498 8, 036 5, 902

100 F., cs 27. 84 23. 81

Pour point, F --75 80 The chemical composition of the monoalkylbenzene fraction, the dialkylbenzene fraction and the blend was as follows (based on mass spectrometer analysisby Z No. Identification).

This example shows the properties of a blend containing 88% dialkylbenzenes and 12% monoalkylbenzenes.

The physical properties were as follows:

Physical properties MAB DAB blend Viscosity at Pour point, I -110 70 -75 The chemical composition of the materials was as follows (based on mass spectrometer ana1ysis-Z No. Identification).

[Mass Spec. (by Z No. Identification)] Compound types volume percent Z No. Identification MAB DAB Blend Dihydronaphthaleues 1. 9 3. 4 3.2 8-- Tetr 18. 5 16. 0 15.7 -6 Alkylbenzenes... 84.3 76. 4 77. 3 Anthracenes 0. 2 O. 2 0.1 0.1 2.0 1.8 I 1. 8 1. 6

Total 100.0 99. 9 99. 9

While particular embodiments of the invention have been described, it will be understood, of course, that the invention is not limited thereto, since many modifications may be made; and it is, therefore, contemplated to cover by the appended claims any such modifications as fall within the true spirit and scope of the invention.

The invention having been described, what is claimed and desired to be secured by Letters Patent is:

1. A synthetic hydrocarbon lubricating composition consisting essentially of from about 70 to about parts by volume of disproportionated product, said disproportionated product comprising at least 55 percent by weight di-n-C -C -alkylbenzenes and being prepared by (1) contacting mono-n-C C -alkylbenzenes with a Friedel- Crafts catalyst at a temperature of from about 20 C. to about 130 C. and (2) recovering from the reaction product the disproportionated product fraction, and about 5 to about 30 parts by volume mono-n-C -C -alkylbenzenes, said lubricating composition containing less than about 4.5 volume percent diphenylalkanes and being characterized further as having the following physical prop erties:

Viscosity, cs. at 210 F.: At least 4.00

Viscosity, cs. at 40 F.: Not more than 13,000

Flash point, COC, F.: Above 290 Pour point, F.: Below -50 2. The hydrocarbon lubricating composition of claim 1 wherein (1) the Friedel-Crafts catalyst used to prepare the disproportionated product is selected from the group consisting of aluminum chloride and aluminum bromide and (2) the cut-point for recovering the disproportionated product from the reaction product is about 197 C. at 5 mm. Hg pressure.

3. The hydrocarbon lubricating composition of claim 2 wherein the Friedel-Crafts catalyst is aluminum chloride.

4. The hydrocarbon lubricating composition of claim 3 characterized further in that it consists essentially of from about 78 to about 92 parts by volume disproportionated product and from about 8 to about 22 parts by volume mono-n-alkylbenzenes.

5. The hydrocarbon lubricating composition of claim 4 characterized further in that it contains less than 2 volume percent diphenylalkanes.

6. The hydrocarbon lubricating composition of claim 5 characterized further in that it has a pour point of below -'65 F.

7. The hydrocarbon lubricating composition of claim 5 characterized further in that it has a flash point of above 450 F.

8. The hydrocarbon lubricating composition of claim 6 characterized further in that substantially all of the alkyl groups in both the di-n-alkylbenzenes and mono-nalkylbenzenes contain from 12 to 14 carbon atoms.

9. The hydrocarbon lubricating composition of claim 7 characterized further in that substantially all of the alkyl groups in both the di-n-alkylbenzenes and mono-nalkylbenzenes contain from 12 to 14 carbon atoms.

10. The hydrocarbon lubricating composition of claim 8 characterized further in that it consists essentially of from about 82 to about '90 parts by volume disproportionated product and from about 10 to about 18 parts by volume mono-n-alkylbenzenes.

11. The hydrocarbon lubricating composition of claim 9 characterized further in that it consists essentially of from about 82 to about 90 parts by volume disproportionated product and from about 10 to about 18 parts by volume monon-alkylbenzenes.

12. A synthetic hydrocarbon lubricating composition consisting essentially of about 13 parts by volume monon-C C -alkylbenzenes and about 87 parts by volume of disproportionated product, said disproportionated product comprising at least 70 percent by weight di-n-'C -C alkylbenzenes and being prepared by (1) contacting mono-n-C -C -alkylbenzenes with a catalyst selected from the group consisting of aluminum chloride and alurninum bromide at a temperature of from about 75 C. to about C. and (2) recovering from the reaction products the fraction distilling above about 197 C. at 5 mm. Hg pressure, said lubricating composition containing less than about 4.5 volume percent diphenylalkanes and being characterized further as having the following physical properties:

Viscosity, at 210 F., cs.: About 4.23

Viscosity, at 100 F., cs.: About 22.75

Viscosity, at 40 F., cs.: About 5981 Flash point, COC, F.: About 400 'Pour point, B: At least about 75.

13. The hydrocarbon lubricating composition of claim 12 wherein the catalyst used to prepare the disproportionated product is aluminum chloride.

DANIEL E.

12 References Cited UNITED STATES PATENTS WYMAN, Primary Examiner I. VAUGHN, Assistant Examiner US. Cl. X.R.