CA1036587A - Synthetic lubricating oils from hydrogenating catalytic cracking of very high viscosity polymers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Hydrogenated synthetic lubricating oils are obtained by subjecting a polymer having a substantially high viscosity and a boiling point higher than 175°C, obtained by polymerizing normal alpha-olefines having the general formula R-CH = CH2 wherein R is an alkyl radical containing from 2 up to 16 carbon atoms, in the presence of a TiCl4/polyiminoalane catalyst and under an inert atmosphere possibly containing hydrogen up to a partial pressure of 1 kg/cm2, to a hydrogenating catalytic cracking carried out at a temperature comprised between 300 and 400°C and under a hydrogen pressure of from 20 to 200 kg/cm2, the volume of liquid per volume of catalyst per hour being comprised between 0.1 and 5, said catalyst contains oxides or sulfides of metals selected from the VI to the VIII group of the Periodical System and is supported on a carrier having a weak Lewis acidity,distilling the resulting product under vacuum up to a head temperature, referred to atmospheric pressure, of 400°C and finally separating the fraction having a boiling point higher than 400°C. The oils thereby obtained present high viscosity indices, very low pour points, low viscosities at 0°F, high flash points, high thermal stability, high resistance to depolymerization and very low carbon reisu.

Description

~36587 : .
The present invention relates to a process for the preparation of synthetic lubricants.
More particularly, according to the process of the . present invention, oils are obtained having high viscosity indices, very low pour points, low viscosities at 0F, remarkable resistance to depolymerization, high thermal stability, very low carbon residue and high flash points.
The process according to the present invention comprises two successive phases.
The first phase has already been described in a copending Canadian patent application no. 194,796 filed March 12, 1974 o~ the same applicant and concerns the preparation of polymers having considerably hiyh molecular weights and viscositi~s compris-:
ed w:ithin the rang~ o~ ~rom 250 cSt up to 15,000 cSt ~ 210E'. Such polymers are ob~ined w~h h~h yie:~s by polyrnerizing normaLa~ha-o~ins mixtures fram wax cracking or single norm~ a~ha-ole~ins having the general formula R-CH -CH2 wherein R is an alkyl radical con-taining ~rom 2 to 16 carbon atoms, in the presence o~ a catalyst formed by the complex TiC14/PIA (tetrachloride of titanium/poly-iminoalane~ and under an inert atmosphere possibly containing - hydrogen up to a partial pressure of 1 kg/cm2, and then by distil-i . .
ling the resulting product up to a head temperature of 175C.
~` The second phase of the process according to the pre-sent invention consists in subjecting the above ob~ained polymers having very high viscosities and boiling points higher than 175 C, ` to a hydrogenating catalytic cracking in order to reduce the mole-cular weight -thereo~ and to obtain thereby oils having viscosities .. . .
` comprised within the ~ield o~ lubricants.

; By means of such hydrogenating catalytic cracking, lubri-cating oils are obtained which present high characteristics and particularly improved thermic stability data.
By suitably changing the type o~ catalyst used and the operative conditions of the hydrogenating cracking, such as tem-:.:.

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3~51~17 . ~ peraturey space veloci-ty and hydrogen pressure, it is possible to obtain oils having any desired viscosi ty, from 4 cSt up to 20, 30 or 50 cSt at 210~.
In the hydrogenating catal~tic cracking treatment of the invention, it is preferable to use catalys-ts containing oxide~
or sul~ides of metals selected from the VI to -the VIII group of the Periodieal System, which are suppor-ted on carriers pos~essing a weak ~ewis acidity7such a3 the allumina type, for the purpose oP
; obtaining as much a~ possible the formation of lo~r boiling products.
'~he variables oP the above treatment are, for a defined catalyst, the temperature~space velocity and hydrogen pressure.
'llhe usePul temperatures are compri~ed between 300 and 4000a. '~he space velocity (L~ISV), expre~ed a~ ~/v/h, i.o., volu-me of liquid per volume of catalyst ~er hour, may ran~ ~rom 0.
to 5, pre~erably Prom 0.25 to 1.5.
'~he hydrogen pres~ure is comprised betwee~ 20 and 200 kg/cm2, pre~erably between 50 and 100 kg/cm2.
'~he hydrogenating ¢atalytic cracking is carried out by cau~ing the polymer, obtained in the first phase, to flow under a controlled hydrogen pressu-re through a tubular reactor electri-, , .
cally heated and containing the hydrogenating catal~st.
~ he resulting productis then fractionated undeI;a reduced pressureup to a head temperature, rePerred to atmosphere pressure of 400C. The residue having a boiling point higher than 400C
. .
constitutes the synthetic lubrica-ting oil of high quality.
Such a~ oil obtained ~rcm the above hydrogenating treat- ;
ment may be considered a~ saturated and~therefore~ does not need Purther hydrogenation. According to the viscosi-t~ of the polymers fed, which may be comprised between 660 ~ld 5330 oSt at 210~, the yield~ o~ oil having a boiling point higher than 400~ range respectively from 66% to 61~o iP oils having a viscosit~ of about 18 cSt at 210F are desired and ~rom 77~0 to 74% if a viscosity oP
about 30 cSt at 210F is needed~
~: .

~5~36587 .
An oil representa-tive o~ the pre~e~t invention~ having :
. ~ a viscosi-ty o~ about 18 cSt at 210F, presents a viscosity index - of 132 i~ calcula-ted according to the ~STM Method D 2270/A, and o~ 158 if calcula~ed according to -the AS'TM Method 2270/~, pour ... point of -48C, very low carbon residue, considerable re~i~tance . to depol~meri3ation, high thermal stability and a fla~h point of :.
.; .
246C. ~ .
'~he present invention will be bet-ter illustrated with ..reference to the .~ollowing examples and accompanying -tables, which must not be con~idered a~ limiting the scope o~ the invention.
; In these examples, the kinematic visco3ities were deter-minated accordin~ to the ASTM D 445 method. '~ne v~scoslty indic~s were reported by me~ns o~ two values, one which i~ calculated accor-ding to the AST~ ~ 2270/A method and the other on~ according to the ASTM D 2270/B method, the la-tter bein~ preferred for viscosity ndices ~ig~er than 100, ~he pour po.int was determ.ined according .
to the hS~ D 97 method and the iodine n~mber according to the IP 84 method.
EXAMP~E 1 20A polymer having a boiling point higher than 175C and a ~.
viscosity of 660 cSt a-t 210~F, obtained by polymerizing C8 - C10 ...
~ alpha-olefines ~rom wax cracking, was subjected to a hydrogenati.ng .,.; .
catalytic cracking according to the invention in order reduce the viscosity thereof and to obtain lubrica-ting oils.
~he treatment was carried out by causing the polymer to ` ~low at a controlled speed and under a hydrogen pressure o~ ~
.~ 50 - 1Q0 kg/cm2 through a tubular (40mm diameter) reactor electri- ;
. cally heated and containing 150 cc o~ a hydrogenating cataly~t i based on Co and Mo and supported on alumina. During the test~, ..
i. 30 there was a gas recycle o~ SCPF/bbl. The product~ obtained in the various tests were then distilled ùnder vacuum up to a head temperature, referred to.atmospheric pressureJ of 400a. The re- ..
, : ~ 3~

; :
~.~3~587 .' sidue having a boiling poin-t higher than 400C cons-tituted the ~ yn-thetic lubricating oil.
The results obtained are shown in -table I. :
~y examining such resul-ts, it may .be no-ticed that the ~ .................. .
'.~ most impor-tan-t variables are the temperature and space velocity, .'. while the hydrogen pressure.presents a negle~ible influence. In fact by maintaining the other variable~ constant, a ~ariation . oE the hydrogen pressure oE from 50 up to 100 kg/cm2 did not . substantially modify the re~ults.
Furthermore, it i~ possible to deduce that hydrogena'ted oils having boiling points higher than 400C and viscosity oE a about 18 cSt at 210~ ~an be obtained either by operatin~ with a space velocity of 0.25 at a temperature oE about 375~ o.r wlt.h a ~pace velocity of 0.5 at a ternperature o:E ~bout 3850a or with ~ '' . a ~pace ~elocity of 1~5 at a ternperature oE ~boub ~ooa.
'.' ~he yields of oil having such viscosity where about ~ equal and were of about 65-66 % by weight. '~he viscosity indices ': were high and the pour point~ very low. .' '~ Moreover, on the basis ofthe value o'~ the iodine number, , . . .
the oils ob-tained can be considered as saturatedO
.20 EX~MPLE ?
~'.................. The polymer used in example 1, having a boiling point higher than 175C and a viscosity of 660 cSt.at 210F, was subjec-ted -to a hydrogenating catalytic crac~;ing wherein use was made o~
. .
.": the same apparatus of example 1 and 150 cc of a catalyst based on cobal-t and molybdenum oxides and supported on a carrier constitu-ted by 25% o~ silice and 75~ E 1/16" alumina. ~he gas recycle was o~ 3000 SCF/bbl.
~he re~ults obtained are reported in ta'ble II.
By comparing these results with the ones of the precee-30 ding e~ample, lt ~ay be noticed that, the viscosit~esbeing equal the yields of oil having a boiling point higher than 400C were~
lower when use was made of a ca-talyst supported on a c~rrier pos---'1-- , .

36587sessing a hig.her acidi-ty ~nd of lower temperatures, It was furthecmore deduced that oils having a viscosity -.
. o~ about 18 cS-t at 210F could be obtained, with the aforesaid . catalyst, by operating either with a space velocity of 0.5 at a . temperature of about 355C or with a space veloci-ty of 1.5 at a !' ' t emperature o~' about 3fi5 ~a.
'l'he yields we.re in both ¢ase o~ about 60~, The vlscosity indices rernained high and the pour points very low.
: EX~MP~E 3 The hydrogenating cat~lytic cracking was carried out .. 10 by us.ing as feed a polymer having a boiling point higher than 175C and a viscosity o~' 5330 cSt a-t 210F, which was obtained from the polymerizatio~ of Ca - C10 alpha-oiefines ~rorn wax cracking. ,.
'l`he oataly~t was the ~ame a~ the one elnployed in e~ample 1, i.e.,.150 cc o~ a ca-talyst based on cobalt and molybdenum oxi-des and supported on alumina, The gas recycle was o~ 3000 SC~/bbl, .. ~he apparatus used was the same as that o~ example 1.
. ~he results obtained are reported in table III. :: .
By comparing such results with the ones of example 1, .. ~ ~:
the tests of which were carried out with the same cat~lyst suppor- ~ -; ~ .
,~ ted on alumina, it may be noticed that, by using as feed a poly- .;
., mer having a higher viscosity for obtaining oils with equal vis-:. cosities, it was ~ecessary to operate. at a higher temperature with .
.. lower resulting yields. : .
. It ma~.be ~urthermore noticed that an oil having a boi-. ling range o~ 400C~ and a viscosity of 18 cSt at 210F was ob- ..
; tained by operating with a space velocit~ o~ 0.5 at a temperature o~ about 390C and that the yields were o~ abou-t 61% b.w. ~he vis- .. .
. .
cosity indice~ o~ the oils of such viscosi-ty were more or les~
;~ 30 equal and the pour point~ remained very low.

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3~5~17 EXAMPLE ~
- '~he synthetic oil obtained according to te~t 11 of example 1 (~ee table I) was selected as representative of the process of the invention. 'This oil was compLetely saturated, as - - shows the value o~ its iodine number.
Other characteristics of such an oil are reported in table IV.
Frorn the values of t~e visco~ity at 210F and at 0F, besides that of the pour point, is is possible to deduce that the oil presents a good behaviour both at high and low temperatures.
A very low value of the carbon residue and a hlgh flash point were furthermore noticed.

'llhe oil ha~ine a boilin~ r~lg~ of 400a~ (boillng at a ;~ temperature higher than 400C) obtai~ec~ according to test 11 of example 1, was subjected to th~ Ra~theon ~ear stability test wi~
:, . , a 90nic oscillator for a time o~ 15 minutes, at a te~aperature of 1 00F (ASI'M D 2603-70) .
. ;j .
'~he results were the following:

. . OI~ ACCOR~ING TO qlEsll 11 0~ EXAMP~E 1 .. : . .
. . As such After test ~- Kinema-tic viscosity at 210F, cSt 17.6 17.6 Kinematic vi9~0sity at 100F, cSt 131 130 ~ rom such result~, it is po3~iblc to deduce that the oil which was obtained a¢cording to the process of the invention present~ a good resistance to the sonic depolymerization test.
.
XAMP~ 6 '~he 400C~ oil obtained according to te~t 11 of exa~ple 1 was subjected to a thermic stability test according to the ~ trademark 6 ' ~

. , ` '', ~ ' ' , ' ~ , -~36S~7 Federal Std method n 2508 "Therm2l Stability o~ ~ubricating and , Hydraulic ~luidsl'~ which co~siæts in maintaining at a tempera-ture : of 260C duri~g 24 hours, 20 cc of the oil under examination i~ aæaled glass tube, the oil being previously subjected to a degasin~
operation.
The results o~ the te~t were -the ~ollowing:
," .

As such After test Ki~ematic vi ~Gosity at 210~, -cSt 17.6 17.5 Kinematic viscosity at 100~, cSt 131 130 ; _ ___ , ..... . .
On the basis o~ the abo~e xesultsJ i.t i~ apparent that , the oil which wa~ obtained according to the process o~ the inven- ;
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tion i8 thermically stable.
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3.~36587 T~ E IV
.~ CHARACTFRISTICS 0~ SA~UR~I~D OI~
~ FROM ~ES~ 11 OF E ~IPIE 1 .. . " ' .
... M e -t h o d Saturated .
oil .
-- - ;: , :~ Specific gra~i~y at 20C ASTM D 1481 0.839 . . .
kinematlc visco~ity at 210F, cSt ~S~M D 4~5 17.6 :
kinematic ~iscosity at `
100F, cSt ~STM D 445 131 ~iscosit~ index ~SIM D 2270/A 132 ~ASI~ D 2270/~ 158 Ab~olute vi~cosity at 0F
(-18C), cP ~STM D 2602 5800 Pour poi~t C ~S'~M D.97 -48 : .
aarbon resldue Ramsbottom % b.w. AS~M D 524 0.010 ~lash point, C ASTM D 92 246 Molecular weight osmom. 650 Iodine number g/100 g IP 84 2.5 '.''`-;: , ."' , .

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Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Process for the preparation of synthetic lubrica-ting oils having high viscosity indices, very low pour points, low viscosities at 0°F, high flash points, high thermal stability, high resistance to depolymerization and very low carbon residue, characterized in that it comprises:
a) subjecting a polymer having a viscosity comprised between 660 and 5,330 cSt at 210°F and a boiling point higher than 175°C, obtained by polymerizing normal alpha-olefines having the general formula R-CH = CH2 wherein R is an alkyl radical containing from 2 up to 16 carbon atoms, in the presence of a TiCl4/polyiminoalane catalyst and under an inert atmosphere possibly containing hydrogen up to a partial pressure of 1 Kg/cm2, to a hydrogenating catalytic cracking carried out at a tempera-ture comprised between 300 and 400°C and under a hydrogen pres-sure of from 20 to 200 Kg/cm , the volume of liquid per volume of catalyst per hour being comprised between 0.1 and 5, said catalyst contains oxides or sulfides of metals selected from the VI to the VIII group of the Periodical System and is supported on a carrier having a weak Lewis acidity;
b) distilling the resulting product under vacuum up to a head temperature, referred to atmospheric pressure, of 400°C and.
c) separating the fraction having a boiling point higher than 400°C.

2. Process according to claim 1, wherein the hydro-genating catalytic cracking is carried out under a hydrogen pressure comprised between 50 and 100 kg/cm2.

3. Process according to claim 1, wherein the volume of liquid per volume of catalyst per hour is comprised between 0.25 and 1.5.

4. Process according to claim 1 or 3, wherein the catalyst used in the cracking step is supported on alumina.