Note: Descriptions are shown in the official language in which they were submitted.
:~7~2~;
-- 1 ~
K 9432
PROCESS FOR THE MANUF~CTURE OF
LUBRICATING BASE OILS FROM NAPHT~IENIC FEEDSTOCKS
The present invention relates to a process for the manufacture
of lubricating base oils from naphthenic feedstocks as well as to
lubricating base oils thus prepared.
One of the major problems associated with the production of
naphthenic base oils from naphthenic feedstocks concerns the
presence o~ naphthenic acids in the feeds to be processed. A
pre-treatment is required to reduce substantially the amount of
naphthenic acids present in the feedstock as they are unacceptable
from a process and product qualit:y point of view.
Reduction of the amount of naphthenic acids can be achieved by
applying a classic clay treatment or a more recent catalytic
hydrofinishing treatment, which moreover also reduces considerably
the amount of sulphur and nitrogen in the feed. Reference is made to
US Patent Specification 2,734,019 wherein a naphthenic lubricating
oil fraction is treated with a cobalt molybdate on alumina catalyst
at an elevated temperature and a moderate pressure (well below 60
bar~ to give a produce with a substantially reduced sulphur content
and a reduced nitrogen content whilst the neutralization number has
been reduced substantially to zero.
It should be noted, however, that the total aromatics content
of the naphthenic feedstock descrlbed in said US patent
specification, being at least 35 ~v, has only been reduced
marginally (i.e. by some 3-5 ~v) by said treatment over the cobalt
molybdate catalyst. Since it becomes increasingly important - for a
variety of reasons - to reduce the amount of aromatics present in
lubricating base oils, in particular those aromatic compounds
referred to as polycyclic aromatics as measured by the IP 346
method, to rather low levels, preferably not exceeding l0 YOW~ it
will be clear that the prior art process leaves much to desire.
~ .
,
... .
, , , , : ~ . ,. . . .: . -
.~ . . ' : ~ ' ' ' : : ' '
:~2'~SZ~S
tt has now leen found that naphtenic feedstocks, l.e. feeds
containing both naphthenic acids and a considerable amount of
aromatic compounds can be converted directly (i.e. without the
necessity of a pre~treatment) into naphthenic base oils of good
quality, having a viscosity index of up to 100 when use is made of
certain fluorided nickel-containing catalysts under rather severe
process conditions.
The present invention thus relates to a process for the
manufacture of naphthenic base oils having a viscosity index of up
]o to 100 by catalytically converting a naphthenic feedstock at
elevated temperature and pressure in the presence of hydrogen, which
process is carried out at a hydrogen partial pressure of at least
100 bar in the presence of a fluorided, nickel-containing catalyst
also comprising tungsten and/or molybdenum.
By using the specific catalyst and process conditions according
to the present invention it has become possible to substantially
reduce the aromatic content of the feedstock in a single operation,
e.g. by at least 50 ~OW, and often by more than 90 ~/OW, starting from
feedstoc~s containing aromatic compounds in amounts of at least
35 %w.
It should be noted that the naphthenic feedstock can, of
course, be sub~ected - if desired - to a neutralization
pre-treatment as referred to hereinbefore so as to reduce almost
completely the acidic components (whilst substantially leaving the
aromatic compounds in the feedstock)~but this is not necessary since
it is the process according to the present invention which allows a
substantial reduction of the initial aromatics content together with
complete removal of the acidic components.
The process according to the present invention can be used
advantageously in the manufacture of low viscosity index base oils
(which are applied e.g. as base oils for cutting oils and as
additive carriers) as well as of medium viscosity index base oils
(whlch are applied e.g. as base oils for refrigerator oils, large
engine lubricating oils as well as in white oil manufacture).
: ~' '. ' ' - :
-
. . - . : .
' . ' . ~ ' ~ '. ' , . ~:
12~SZ~S
-- 3 ~
Naphthenic base oils having a low viscosity index can now be
prepared in far higher yields and at a much lower polyc~clLc
aromatic components level than is possible when using a conventional
hydrotreatment and/or acid/clay treatment. It is now possible to
reduce the polycyclic aromatic content to well below 10 %w and often
to less than 6 %w, and even less than 3 %w which is of great
importance from an environmental point of view.
Naphthenic base oils having a medium viscosity index can now be
prepared in much higher yields by the process according to the
present invention than is achievable by using common solvent
extraction of neutralized feedstocks, followed, if desired, by a
hydrofinishing step.
Both neutralized and unneutralized naphthenic base oil
feedstocks can be suitably applied in the process according to the
present invention. Preferred feedstocks comprise unneutrali~ed
naphthenic distillates since they can be converted in a single
operation into valuable naphthenic base oils. The naphthenic
distillates to be used may contain up to ~ /OW of sulphur and up to
0.8 %w of nitrogen compounds. The acid number may be as high as 10
mg KOH/g. The naphthenic base oil feeclstocks to be processed
normally contain at least 35 ~/OW of aromatic compounds and often even
more then than 65 %w.
It is also advantageous to use blends of two or more
(un)neutralized naphthenic distillates as this increases the
flexibility in the production of various gr~des of lubricating basP
oils depending on the composition of the blend to be processed and
the severity of the conversion process itself.
The process according to the present invention has to be
carried ou~ at a hydrogen partial pressure of at least 100 bar
30 (104kPa) and preferably at a pressure between 100 and 200 bar.
Temperatures between 280 C and 425 C can be suitably applied;
preference is given to the use of temperatures between 325 and
400 C, depending to some extent on the base oil feedstock to be
processed and the base oil grade to be produced. Normally, the
35 hydrotreatment according to the present invention will be carried
.. . . . . . . .
.
:' :
S~'7~
-- 4 --
out at a space valocity between 0.1 and 5 kg/kg.h, in particular
between 0.2 and 2 kg/kg.h.
It has been found that the supported catalysts to be used in
the process according to the present invention have to contain
molybdenum and/or tungsten in addition to nickel.
The amount of nickel present in the catalyst can suitably vary
between 1 and 20 %w, calculated as oxide on total catalyst
composition, preference being given to amounts in the range of from
2 to 12 ~w. The amounts of molybdenum and tungsten may vary between
lO and 40 %w, calculated as oxide on total catalyst composition,
preference being given to amounts in the range between 10 and 30 %w.
Preferred catalysts contain both nickel and tungsten.
The metals and/or metal compounds may be incorporated into the
supports by any conventional technique, such as impregnation,
dry-impregnation, precipitation and combinations thereof. It is also
possible to prepare the catalysts by the hydrogel or the xerogel
methods as described in British Patent Specifications 1,493,620 and
1,546,398.
Any suitable support material may be used such as refractory
oxides conventionally used for hydrotreating catalysts, such as
silica, alumina, magnesia, ~irconia and mixtures thereof. Silica and
alumina are preferred support materials, in particular alumina.
Natural and synthetic crystalline aluminosilicates such as
faujasite, in particular Y-faujasite, and ZSM-5 type carriers can
also be applied.
The catalysts according to the present invention also contain
fluorine. The amount of fluorine in the catalysts under operating
conditions may vary between 0.5 and 10 ~OW, preferably between 2 and
8 %w, calculated on total catalyst. Fluorine can be introduced into
the catalyst by one or more of the fluorination techniques known in
the art. Preference is given to the introduction of at least part of
~he fluorine required in the catalyst by means of in-situ
fluorination. It is advantageous to incorporate substan~ially all
fluorine required in the catalyst by in-situ fluorination,
preferably in the initial stage of the hydrotreatment. It is also
.
.~ ' : . .- ~ :
': ,. ' ' '
~12';~5~
5 -
possible ~o supply, either continuously or intermlttantly, a small
amount of fluorine, e.g. between 5 and 100 ppm, calculated on
feedstock, during the hydrotreating process. Th:Ls can be suitably
achieved by adding an appropriate fluorine compound, e.g.
difluoroethane or o-fluoro toluene, to the feedstock to be
processed, The catalysts may also contain other compounds such as
phosphorus or boria.
The catalyst can be applied in the fonn o~ spheres or
extrudates. The extrudates may have different shapes depending on
the extrusion equipment used during their preparation.
The present invention will now be illustra~ed by means of the
following Examples.
Example 1
An unneutralized blend of various naphthenic distillates of
South American origin, containing 1.8 %w of sulphur, a total
nitrogen content of 760 ppm and an aromatics content of 55 70w,
including 10.4 %w of polycyclic aromatic compounds was hydrotreated
at a hydrogen partial pressure of 140 bar at a temperature of 345 C
and at ~ space velocity of 0.8 kg/kg.h over a commercially available
fluorinated nickel-tungsten on alumina catalyst. Naphthenic base
oils were obtained in a yield exceeding 95 %w, calculated on
starting material. They contained less than 4 %w of polycyclic
aromatic compounds, less then 250 ppm of nitrogen and not more than
0.25 %w of sulphur.
2r Example 2
An unneutralized blend of va~ious naphthenic distillates of
South American origin containing 1.8 %w of sulphur, a total nit~ogen
content of 760 ppm and an aromatic content of 55 %w, including
10.4 %w of polycyclic aromatic compounds was hydrotreated at a
hydrogen partial pressure of 140 bar at a temperature of 360 C and
at a space velocity o~ 0.8 kg/kg.h over a commercially available
fluorlnated nickel-tungsten on alumino catalyst. Naphthenic base
oils were obtained containing less than 2.5 %w of polycyclic
aromatic compounds whereas the amounts of sulphur were reduced to
0.06 %w and below and nitrogen to 73 ppm and below. The yield of the
naphthenic base oils was 97%, calculated on unneutralized feedstock.
..
., ' '
. ~ ,' '
-. . ~
~;~7 5i~7~
-- 6 --
Example _
An unneutralized naphthenlc distillate of South American origin
containing 1.73 ~w of sulphur, a total nitrogen content of 315 ppm,
an aromatics content of 49.8 ~w, including 13.7 %w of polycyclic
aromatic compounds and having a total acid number of 5.7 (mg KOH/g)
was hydrotreated using the catalyst described in Example 1 at 378 C
using the same space velocity as described in said Example. A
naphthenic base oil having an initial boiling point of 280 C and a
viscosity index of 45 was obtained in 5~.2 ~w yield, calculated on
unneutralized starting material. The base oil obtained contained
less than 5 ppm of nitrogen and less than 40 ppm of sulphur. The
total aromatic content had been reduced to less than 7 ~w, the
amount of polycyclic aromatic compounds being even less than l %w.
Example 4
An unneutralized naphthenic distillate of South American origin
containing 2.35% of sulphur and 1576 ppm of nitrogen, a total
aromatics conten~ of 63.9 ~w, including 31.5 %w of polycyclic
aromatic compounds and having a total acid number of 7.8 was
hydrotreated at 380 C and at a hydrogen partial pressure of 140 bar
at a space velocity of 0.6 kg/kg.h. A naphthenic base oil having an
initial boiling point of 400 C and a viscosity index of 35.8 was
obtained in 59.4~ yield, calculated on unneutralized starting
material. The base oil obtained contained less than l ppm of
nitrogen and no detectable amounts o~ sulphur. The total aromatics
content amounted to 21.8 ~Ow, only 1.8 ~/~w being attributed to poly-
cyclic aromatic compounds.
'
: , . , . , '~ ' '
-
.
- . : ,
