GB2078247A

GB2078247A - Oxidation-resistant Oil Composition

Info

Publication number: GB2078247A
Application number: GB8019729A
Authority: GB
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1980-06-17
Filing date: 1980-06-17
Publication date: 1982-01-06
Also published as: FR2484440A1; GB2078247B; FR2484440B1

Abstract

An oxidation-resistant oil composition suitable for use as an electrical oil or a turbine oil is made by forming a blend comprising 85 to 99.9 wt % of a hydrocarbon alkylate oil and 15 to 0.1 wt % of a refined fraction having a sulfur content of at least 1.0 wt % made by catalytically hydrogen-refining a hydrocarbon fraction having an aniline point not exceeding 60 DEG C and a sulfur content of at least 2.0 wt %, the catalytic hydrogen refining conditions comprising a temperature in the range 220 DEG C to 300 DEG C and a hydrogen partial pressure in the range of from 20 to 50 bars. In one embodiment, the hydrocarbon alkylate oil is propylene tetramer alkylate of benzene, and the hydrocarbon fraction is a fraction obtained from a thermal or catalytic cracking operation.

Description

SPECIFICATION Process for Production of Oxidation-Resistant Oil Composition, and Oxidation-Resistant Oil Composition Made Thereby The present invention relates to a process for the production of an oxidation-resistant oil composition and to an oxidation-resistant oil composition made thereby.

It is a common requirement that oil compositions should be stable, particularly to oxidation, and more particularly if there intended use extends over a relatively long period of time before they are replaced and/or discarded. The oxidation-stability of oil compositions is the more important and difficult to achieve because the usual conditions of use tend to promote oxidative degradation.

The present invention provides a process for producing an oil composition of high resistance to oxidation comprising the steps of: (a) subjecting a hydrocarbon fraction boiling in the temperature range of the desired final composition and having an aniline point not exceeding 600C and a sulfur content of at least 2.0 wt % to a catalytic hydrogen-refining treatment at a temperature in the range of from 2200C to 3000C and a partial pressure of hydrogen in the range of from 20 to 50 bars to produce a refined fraction having a sulfur content of at least 1.0 wt. %; and (b) forming a blend comprising from 85 to 99.9 wt % of a hydrogen oil made by alkylation and boiling in the temperature range of the desired final composition and 15 to 0.1 wt % of said refined fraction.

Preferably, the alkylate hydrocarbon oil and preferably the said refined fraction boil in the lube oil boiling range.

The blend obtained by the process of the invention is suitable for such uses as e.g. an electrical oil or a turbine oil.

An important advantage of the process of invention is that the physical properties of the resulting oil compositions are largely determined by the nature of the alkylate hydrocarbon oil, and within limits, it is possible to synthesize alkylate hydrocarbon oils to have physical properties, such as, e.g. viscosity, pour point and flash point, within a predetermined desired range.

Preferably, the hydrogen partial pressure in step (a) is in the range of from 30 to 40 bars, and preferably the temperature in step (a) is in the range of from 240 to 2800C.

Preferably, the said hydrocarbon fraction has an aniline point not exceeding 350C before the catalytic hydrogen-refining step, and preferably the refined fraction produced by step (a) has a sulfur content of at least 2.0 wt %.

The hydrocarbon fraction may have a sulfur content of at least 3.5 wt % before the catalytic hydrogen-refining step.

Step (a) may be performed at a LHSV (h-') in the range of from 0.3 to 2.0.

The catalytic hydrogen-refining of step (a) is preferably performed in the presence of a catalyst comprising a Group VI metal component and a non-noble Group VIII metal component.

The hydrocarbon fraction may be an aromatics-rich hydrocarbon fraction obtained by thermal or catalytic cracking of a heavy hydrocarbon feedstock. Thermal cracking, of course, includes steam cracking.

The said hydrocarbon oil is preferably made by the alkylation of an aromatic hydrocarbon with an olefin polymer, and preferably the olefin polymer is a polymer of propylene. A suitable olefin polymer comprises dodecane obtained by the polymerization of propylene in the presence of a catalyst comprising either BF3 and H20 or phosphoric acid.

Suitably, the aromatic hydrocarbon is benzene or mainly benzene.

The alkylation may be catalyzed by a catalyst comprising AICI3 or by any other of the well-known alkylation catalysts.

The present invention also provides an oil composition of high resistance to oxidation made by a process as described above.

The invention is now further described with reference to a non-limitative example thereof: A synthetic hydrocarbon base oil having physical characteristics suitable for use as a dielectric oil in a transformer was made as follows: Propylene was passed in contact with a commercially available polymerization catalyst comprising BF3 and water, and a C12 olefin polymer fraction was recovered from the polymer products.

The recovered polymer fraction was used to alkylate benzene in the presence of an alkylation catalyst comprising AICI3. The resulting alkylate, after purification, was found (by gas chromatography) to comprise 96 wt % of C12-al kylbenzene and 4 wt % of Cg to Cx5 alkylbenzenes. The alkylate had the following inspections: Viscosity (cS) @ -300C 505 OOC 3 1.6 2000 11.5 2100F(98.90C) 1.7 Flash point, COO, CC 133 Pour point CC -60 Bromine No. 0.25 The foregoing inspections suggest that the alkylate would be suitable for use as a transformer oil.

An accepted test of the suitability of transformer oils is the well-known BaaderTest. The alkylate was subjected to the BaaderTest, and the resulting Baader saponification No. was 4.2 mg.KOH/g which is well above the maximum limit of 0.6 mg.KOH/g set by the Verbindung Deutsche Elektrotechnische and adopted as the West German standard Dl N 0370.

Blends of the alkylate were formed with different sulfur-rich fractions containing aromatic hydrocarbons and which had been subjected to a catalytic hydrogen-refining treatment under relatively mild treating conditions.

One such fraction A was a fraction boiling in approximqtely the same range as the alkylate and obtained from a catalytic wracking operation. Another such fraction B was obtained by the distillation of a tar produced during steam cracking.

Fractions A and B were mildly hydrogen-refined in the presence of a catalyst of supported Ni and Mo under the following hydrogen-refining conditions: LHSV (h-') 0.7 H2 partial pressure (bars) 30 H2/fraction vol ratio 100 Temperature 240 The properties of fractions A and B before and after catalytic hydrogen refining were as follows: A B before after before after refining refining refining refining Refractive Index at 6000 1.587 1.572 1.631 1.615 Specific Gravity at 1500 1.007 0.989 1.060 1.051 Aniline point ( C) 33 32 14 9 Viscosity at 4000 15.6 13.3 8.7 7.4 Sulfur content (w.%) 3.5 2.4 5.0 4.0 Nitrogen content (ppm) 810 740 820 750 A blend was formed of 95 wt.% of the alkylate and 5 wt.% of each of the hydrogen-refined fractions A and B. Each blend was investigated for oxidation stability by the Baader test, and the results were as follows:~ Baader Saponification Blend No. fmg.KOHlg) 95 wt. % alkylate+5% refined A 0.06 95% alkylate+5% refined B 0.03 It will be seen from the foregoing that the blend of alkylate with a small proportion of the hydrogen-refined sulfur-rich, a romatics-rich fractions dramatically reduced the Baader saponification number, relative to that of the pure alkylate, to a value well below the maximum specified by DIN 0370. Such blends are well suited to applications where oxidation stability is important.

Similar benefits are obtained by the use of the invention when the alkylate is, e.g. a polyalphaolefin.

Claims

1. A process for producing the oil composition of high resistance to oxidation comprising the steps of: (a) subjecting a hydrocarbon fraction boiling substantially in the temperature range of the desired final composition and having an aniline point not exceeding 6000 and a sulfur content of at least 2.0 wt % to catalytic hydrogen-refining treatment at a temperature in the range of from 22000 to 30000 and a partial pressure of hydrogen in the range of from 20 to 50 bars to produce a refined fraction having a sulfur content of at least 1.0 wt %; and (b) forming a blend comprising from 85 to 99.9 wt % of a hydrocarbon oil made by alkylation and boiling in the temperature range of the desired final composition and 1 5 to 0.1 wt % of said refined fraction.

2. A process as in claim 1 in which the hydrogen partial pressure in step (a) is in the range of from 30 to 40 bars.

3. A process as in claim 1 or claim 2 in which the temperature in step (a) is in the range of from 240 to 28000.

4. A process as in any one of claims 1 to 3 in which the said hydrocarbon fraction has an aniline point not exceeding 350C before the catalytic hydrogen-refining step.

5. A process as in any one of claims 1 to 4 in which the refined fraction produced by step (a) has a sulfur content of at least 2.0 wt %.

6. A process as in any one of claims 1 to 5 in which the hydrocarbon fraction has a sulfur content of at least 3.5 wt %.

7. A process as in any one of claims 1 to 6 in which step (a) is performed at a LHSV (h-') in the range of from 0.3 to 2.0.

8. A process as in any one of claims 1 to 7 in which the catalytic hydrogen-refining of step (a) is performed in the presence of a catalyst comprising a Group VI metal component and a non-noble Group VIII metal component.

9. A process as in any one of claims 1 to 8 in which the hydrocarbon fraction is an atomaticsrich hydrocarbon fraction obtained by thermal or catalytic cracking of a heavy hydrocarbon feedstock.

10. A process as in any one of claims 1 to 9 in which the said hydrocarbon oil has been made by the alkylation of an aromatic hydrocarbon with an olefin polymer.

11. A process as in claim 10 in which the olefin polymer is a polymer of propylene.

12. A process as in claim 11 in which the olefin polymer comprises dodecane obtained by the polymerization of propylene in the presence of a catalyst comprising either BF3 and H 20 or phosphoric acid.

13. A process as in any one of claims 10 to 12 in which the aromatic hydrocarbon is benzene or mainly benzene.

14. A process as in any one of claims 10 to 13 in which the alkylation has been catalyzed by a catalyst comprising AICI3.

15. A process for producing an oil composition of high resistance to oxidation substantially as hereinbefore described.

16. An oil composition of high resistance to oxidation made by a process according to any one of claims 1 to 15.