NO140138B - PROCEDURE FOR THE PREPARATION OF SYNTHETIC LUBRICATION OILS BY POLYMERIZATION OF ALFA OLEFINES, CATALYTIC CRACKING, VACUUM DISTILLATION AND HYDROGENATION - Google Patents

Description

The present invention relates to a method for

position of synthetic lubricating oil with a high viscosity index,

very low pour point, low viscosity at -18°C, high thermal stability, good resistance to depolymerisation, high flame-

point and very low carbon residue, and the distinctive

the way according to the invention is that the polymers with high kinematic viscosity and boiling point higher than 175°C, obtained by polymerization at a manometric pressure of up to 1 kg/cm<2>

under an atmosphere of hydrogen and/or inert gas of normal α-olefins of the general formula R - CH = in which R is an alkyl radical with from 2 to 16 carbon atoms in the presence of the catalyst TiCl^/polyiminoalane, is subjected to catalytic cracking at atmospheric pressure at temperature from 250 to 300°C, with volume of liquid per volume of catalyst per hour is from 0.1 to 5, preferably from 0.5 to 2, the product obtained is distilled under vacuum to separate a distillation residue with a boiling point higher than 400°C at atmospheric pressure and this residue is hydrogenated catalytically.

The method according to the invention therefore mainly comprises two successive phases.

The first phase involves the production of polymers with a fairly

high molecular weight, with a wide range of viscosities between

250 cSt and 15,000 cSt at 99°C. These polymers are obtained with high yield by polymerizing mixtures of normal a-

olefins from wax cracking or of simple normal α-olefins with a general formula R - CH = CH2 in which R is an alkyl radical with from 2-16 carbon atoms, in the presence of a catalyst formed by the complex TiCl^/PIA (titanium tetrachloride/ polyiminoalane) by working in a hardened atmosphere or at least partially

added hydrogen and in any case at a manometric hydrogen pressure of no higher than 1 kg/cm and then by distilling the polymerization product up to a peak temperature of 175°C.

In the second phase of the method according to the invention, whereby synthetic lubricating oils are obtained, the polymer with a very high viscosity with a boiling point higher than 175°C, obtained in the first phase, is subjected to a catalytic cracking at atmospheric pressure,

to reduce the molecular weight of the polymers and obtain oils with viscosities within the range of lubricants.

In the aforementioned treatment with catalytic cracking of the polymers

ia&<3 a very high viscosity, lubricating oils with good properties are obtained

creates and especially their results with regard to thermal stability are improved considerably.

By appropriately changing catalyst type and operating conditions,

temperature and volume rate, oils can be obtained with all the desired viscosities, from 4 cSt up to 20 - 30 - 50 cSt at 99°C.

In the treatment with catalytic cracking of the polymers with a high molecular weight, it is preferred to use catalysts on supports with a weak acidity according to Lewis (of the alumina type)

in order to achieve as large a formation of low-boiling products as possible.

The catalyst itself advantageously consists of oxides or sulphides

of the metals in groups VI to VIII of the periodic table.

In the method according to the invention, with the use of a

particular catalyst, the variable factors are the temperature,

and the volume velocity. The usable temperatures range between

250 and 300°C. The volume velocity, LHSV, expressed as v/v/h, as liquid volume per volume of catalyst per hour, can be from 0.1 to 5", preferably between 0.5 and 2.

The catalytic cracking was carried out by bringing the very high viscosity polymer obtained in the first phase to flow at atmospheric pressure through a tubular electrically heated reactor containing the catalyst. The product thus obtained is fractionated at reduced pressure, up to a peak temperature, referred to atmospheric pressure, of <1>+00°C. The remainder with a boiling point higher than <1>+00°C constitutes the synthetic lubricating oil whose yield is calculated in weight-$ on the basis of the polymer with a boiling point higher than 175°C used as feed material.

Depending on the viscosity of the added polymers, in the range from 660 cSt up to 1,150 cSt at 99°C, the treatment gives yields in a range from 61 to 57$ if oils with a viscosity at 210°C of about 18 cSt are desired, and from 72 to 67% if oils with viscosities of about 30 cSt are desired.

The oil with a boiling point higher than <1>+00°C, obtained by the said treatment, is then subjected to hydrogenation to eliminate the unsaturation present in the oil.

The hydrogenation can be carried out by conventional and known methods. In particular, the hydrogenation is carried out in the presence of a catalyst containing 0.3$ Pd on aluminum oxide, at a temperature of 200 o C at an output hydrogen pressure of 100 kg/cm 2 , in the course of a total of 5 hours.

The hydrogenated oil with a boiling point higher than <i>fOO°C is the desired high quality synthetic lubricating oil.

A hydrogenated oil prepared according to the present invention, having a viscosity of about 19 cSt at 99°C,

has a viscosity index of 130? calculated in accordance with ASTM D 227O/A, and of 15<*>+ if calculated in accordance with ASTM'D 2270/B, a pour point of -50°C, considerable resistance

against dcpolymerization, high thermal stability, very low carbon residue, and ignition point of 2Lt-5°C.

The present invention shall be illustrated by means of the

following examples of preferred and exemplary embodiments.

In the examples, the kinematic viscosities were determined according to ASTM D M+5. For viscosity indices two values were determined, one calculated in accordance with ASTM D 2270/'A and the other in accordance with ASTM D 2270/B which is more correct, for viscosity indices higher than 100. The pour point was determined in accordance with D 97 - method. The iodine number was determined in accordance with the IP 8^ method.

Example 1.

A polymer with a boiling point higher than 175°C, obtained by polymerization of Cg - a -olefins from wax cracking, and with a viscosity at 99°C of 660 cSt, was subjected to catalytic cracking to reduce its viscosity and obtain lubricating oils . The treatment was carried out by causing the polymer to flow at atmospheric pressure and at a controlled rate through a tube-shaped electrically heated steel reactor of ho mm diameter, containing a catalytic layer of 200 ml of activated alumina, with a content of 99$ A12°3 (tablets approx. 3 nm)«

The products obtained in the various samples were distilled under vacuum up to a peak temperature at atmospheric pressure of k00°C. The rest, which had a boiling point higher than k00°C, constituted the synthetic lubricating oil.

The results obtained are reproduced in table I.

0

These samples showed that by catalytic cracking of a polymer with a viscosity of 660 cSt at 99°C, lubricating oil could be obtained by working at relatively low temperatures.

From a graphical representation, it was deduced that an oil having a viscosity of about 18 cSt at 90°C could be obtained with a yield of about 61% by weight, by operating at a temperature of about 268°C and a volume velocity of 1 .

Example 2.

The catalytic treatment was carried out by using as feed material a polymer with a boiling point higher than 175°C, obtained by polymerization of Cg - C1Q olefins from wax cracking and with a viscosity at 99°C of 1,160 cSt. The catalyst was the same as that used in example 1, and exactly 200 ml of activated alumina containing 99% Al 2 O 3 (tablets approx. 3 mm) were used.

The apparatus used was the same as in example 1.

The results of these trials are reproduced in table II.

By examining these results, it was deduced that by using as feed material a polymer with a viscosity of 1,160 cSt at 99°C, lubricating oils could be produced by working at relatively low temperatures.

From a graphical representation it was possible to deduce that an oil with a viscosity of about 18 cSt at 99°C could be obtained with a yield of about 57% by weight by working at a volume rate of 1 and a temperature of about 270°C .

Example 3.

The synthetic oil with a boiling point higher than U-00°C obtained in trial 2 of example 2 (see Table II) was hydrogenated for complete saturation of the olefinic double bonds. The operation was carried out in an autoclave in the presence of a catalyst containing 0.3% Pd on alumina at a temperature of

200 C, under a hydrogen pressure of 100 kg/cm, for a total of 5 hours.

The properties of the oil before and after hydrogenation are reproduced in Table III. From the above results, it was noted that the hydrogenation did not significantly modify the properties of the oil, which was still very good.

From the value for viscosities at 99°C and -18°C, as well as from the pour points, it was possible to conclude that the oil would have good properties both under hot and cold conditions.

Furthermore, the very low values for carbon residue and the high flash point were noted.

Example h.

The hydrogenated oil from example 3 was subjected to a test

on stability against shear stress with a "Raytheon" sonic oscillator for 15 minutes, at a temperature of 38°C (ASTM D 2603-70). The results are reproduced in table IV.

By looking at these results, it was possible to conclude that the hydrogenated oil obtained by the method according to the invention was resistant to the so-called sound depolymerization test.

Example 5.

The hydrogenated oil of Example 3 was subjected to a thermal stability test according to Federal Std. No. 2508 "Thermal Stability of Lubricating and Hydraulic Fluids", which consisted of keeping 200 ml of the oil at a temperature of 260°C for 2 hours,

for testing in a glass rudder which had been fused with flame when the oil had first been degassed.

The results of the test are reproduced in table V.

On the basis of the previous results, it is possible to confirm that the obtained oil was thermally stable.

Claims (2)

1. Process for the production of synthetic lubricating oil with a high viscosity index, very low pour point, low viscosity at -18°C, high thermal stability, good resistance to depolymerization, high flash point and very low carbon residue, characterized in that the polymers with high kinematic viscosity and boiling point higher than 175°C, obtained by polymerization at a manometric pressure of up to 1 kg/cm 2 under an atmosphere of hydrogen and/or inert gas of normal α-olefins of the general formula R - CH = CH2 in which R is a alkyl radical with from 2 to 16 carbon atoms in the presence of the catalyst TiCl^/polyiminoalane, is subjected to catalytic cracking at atmospheric pressure at a temperature from 250 to 300°C, since liquid volume per volume of catalyst per hour is from 0.1 to 5, preferably from 0.5 to 2, the obtained product is distilled under vacuum to separate a distillation residue with a boiling point higher than 400°C at atmospheric pressure and this residue is hydrogenated catalytically.. 2. Method as stated in claim 1, characterized in that a cracking catalyst is used containing oxides or sulphides of the metals in groups VI to VIII of the periodic table, arranged on a carrier with weak Lewis acidity.