AN IMPROVED METHOD FOR MAKING A PROCESS OIL BY USING AROMATIC ENRICHMENT WITH EXTRACTION FOLLOWED BY SINGLE STAGE HYDROFINISHING

UNE METHODE AMELIOREE POUR PRODUIRE UNE HUILE DE MISE EN OEUVRE PAR ENRICHISSEMENT AROMATIQUE AVEC EXTRACTION SUIVI D'UN HYDROFINISSAGE EN UNE ETAPE

English Abstract

A method for producing a process oil is provided in which an aromatic
extract oil is added to a paraffinic rich feed to provide a blended feed. The
blended
feed is then extracted with an aromatic extraction solvent to yield a
raffinate which
subsequently is hydrotreated to provide a process oil.

Claims

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THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for producing a process oil comprising:
adding an aromatic extract oil to a paraffinic rich feed to provide a
blended feed;
extracting the blended feed with an aromatic extraction solvent at
a temperature of from about 50°C to about 150°C and a solvent to
feed ratio of about
0.5:1 to about 3:1 to obtain a raffinate for hydrotreating;
hydrotreating the raffinate in a single hydrotreating stage at a temperature
of about 275°C to about 375°C and a hydrogen partial pressure of
about 300 to about
2500 psia at a space velocity of about 0.1 to about 2.0 v/v/hr whereby a
process oil is
produced.
2. The method of claim 1 wherein the aromatic extraction solvent
contains from about 1 vol% to about 20 vol% water.
3. The method of claim 1 wherein the paraffinic rich feed is a
paraffinic distillate.
4. The method of claim 3 wherein aromatic extract oil is added to
the paraffinic feed in the volume ratio of about 10:90 to about 90:10.
5. The method of claim 4 wherein the volume ratio of aromatic
extract oil to paraffinic feed is the range of 25:75 to 50:50.
6. The method of claim 5 wherein the extraction solvent contains
greater than 5 vol% water.

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7. The method of claim 6 wherein the aromatic extract oil has an
aromatic content of about 50% to 90% by weight.
8. The method of claim 1 including dewaxing of the paraffinic rich
feed or the hydrofinished oil using catalytic dewaxing or alkane or ketone
dewaxing.
9. A method for producing a process oil comprising:
(a) solvent extracting a naphthenic rich feed with an aromatic
extraction solvent to obtain an aromatic rich solvent stream;
(b) removing the solvent from the aromatic rich solvent stream to
obtain an aromatic extract oil;
(c) adding the aromatic rich extract oil to a paraffinic rich feed to
obtain a blended feed;
(d) extracting the blended feed under milder conditions than the
extraction of step (a) with an aromatic extraction solvent at a temperature of
about 50°C
to about 150°C, and a solvent to feed ratio of about 0.5:1 to about 3:1
to obtain a
raffinate;
(e) hydrotreating the raffinate at a temperature in the range of about
275°C to about 375°C, at a hydrogen partial pressure of about
300 to about 2500 psia at
a space velocity of about 0.1 to about 2.0 v/v/hr.
10. The method of claim 9 wherein the aromatic extraction solvent
of step (d) contains from about 1 vol% to about 20 vol% water.
11. The method of claim 10 wherein the solvent of contains greater
than about 5 vol% water.

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12. The method of claim 9 of step (c) wherein the volume ratio of
aromatic extract oil to paraffinic feed in the blended feed is in the range of
about 10:90
to about 90: 10.
13. The method of claim 12 wherein the volume ratio of aromatic
extract oil to paraffinic feed is in the range 25:75 to 50:50.
14. The method of claim 8 wherein the feed or hydrotreated raffinate
oil is dewaxed using catalytic dewaxing or alkane or ketone or catalytic
dewaxing.

Description

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AN IMPROVED METHOD FOR MAKING A PROCESS OIL BY
USING AROMATIC ENRICHMENT WITH EXTRACTION FOLLOWED
BY SINGLE STAGE HYDROFI1VISHING
FIELD OF THE INVENTION
The present invention is concerned generally with the production of
process oils from paraffinic rich feeds.
BACKGROUND OF THE INVENTION
The properties of paraffinic rich feeds make them particularly useful in a
broad range of oils used in a wide variety of industrial applications. For
example, the
paraffinic oils may be used in rubber processing for reasons such as reducing
the
mixing temperature during the processing of the rubber, and preventing
scorching or
burning of the rubber polymer when it is being ground down to a powder, or
modifying
the physical properties of the finished rubber. These oils are finished by a
refining
procedure which imparts to the oils their excellent stability, low staining
characteristics
and consistent quality.
End-users of such process oils desire oils with increased solvency as
indicated by a lower aniline point. Accordingly, one object of the present
invention is
to provide a process oil that has a lower a aniline point and consequently
increased
solvency above what could be obtained from paraffinic distillates alone, by
using
paraffinic distillates in admixture with their co-produced extracts.
Due to the decline in the availability of conventional naphthenic feeds,
paraffinic distillates are being substituted for portions or all of some
naphthenic
distillates since the demand for higher solvency process oils is still
increasing.
Accordingly, it is another object of the present invention to provide process
oils with
increased solvency using lesser amounts of paraffinic rich feeds.
SUMMARY OF THE INVENTION
A method for producing a process oil is provided which comprises:

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adding an aromatic containing extract oil to a paraffinic rich feed to
provide a blended feed for processing;
extracting the blended feed with an aromatic extraction solvent at
temperatures in the range of about 50°C to about 150°C and at
solvent to feed ratios in
the range of about 0.5:1 to about 3:1 by volume to obtain a raffinate for
hydrofinishing;
and then hydrotreating the raffinate in a hydrotreating stage maintained
at a temperature of about 275°C to about 375°C, a hydrogen
partial pressure of about
300 to about 2500 psia, and at a space velocity of about 0.1 to about 2.0
v/v/hr to
provide a process oil.
These and other embodiments of the present invention will become
apparent after a reading of detailed description which follows.
DETAILED DESCRIPTION OF THE INVENTION
Typically the paraffinic rich feed used to produce process oils in
accordance with the method of the present invention will comprise virgin
and/or
synthetic hydrocarbons, although other paraffinic rich materials obtained by
extraction or alkane or ketone dewaxing, catalytic dewaxing and the like may
be
utilized.
In accordance with the present invention, an aromatic extract oil is
added to the paraffinic rich feed to provide a blended feed for hydrotreating.
Preferably the aromatic extract oil used in the present invention will have an
aniline
point less than about 60°C for high viscosity oils (e.g., greater than
about 35 cSt @
100°C) and less than about 70°C for low viscosity oils (e.g.,
about 2 cSt to about 35
cSt @ 100°C).

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Such an aromatic oil suitable in the process of the present invention is
readily obtained by extracting a naphthenic or paraffinic rich feed such as a
distillate
with aromatic extraction solvents at temperatures in the range of about
50°C to about
150°C in extraction units known in the art. Typical aromatic extraction
solvents include
N-methylpyrrolidone, phenol, N-N-dimethylformamide, dimethylsulfoxide,
methylcarbonate, morpholine, furfural, and the like and preferably N-
methylpyrrolidone
or phenol. Solvent to oil treat ratios are generally about 0.5:1 to about 3:1.
The
extraction solvent preferably contains water in the range o~ about 1 vol.%o to
about 20
vol. %. Basically the extraction can be conducted in a counter-current type
extraction
unit. The resultant aromatic rich solvent extract stream is then solvent
stripped to
provide an aromatic extract oil having an aromatic content of about 50% to 90%
by
weight.
The aromatic extract oil is mixed with the same or different viscosity
parafflnic rich feed in an extract to feed volume ratio in the range of about
10:90 to
about 90:10, preferably 25:75 to 50:50. Typical but not limiting examples of
paraffinic
feed and extract oils are provided in Tables 1 and 2 for Ivw and high
viscosity oils,
respectively.

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TABLE I
LOW VISCOSITY PARAFFINIC FEED AND EXTRACT OIL - 75N
Physical Properties (Waxy) Paraffinic Feed Extract Oil
Density, 15C 0.8866 0.9332
Calc Viscosity cSt @ 100C 3.2 3.6
Refractive Index @ 75C 1.4713 1.5021
Aniline Point, C 81.3 53.0
Pour Point, C 21.0 12.0
Sulfur, wt.% 1.2 2.0
Dewaxed Viscosity Index @ 71 N/A*
-9C Pour
Compositional Properties
(Waxy)
Saturates, wt.% 62 44
Polars & Aromatics, wt.% 38 56
* Viscosity Index of coproduced raffinate at -9°C pour is 95

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TABLE 2
HIGH VISCOSITY PARAFFINIC FEED AND EXTRACT OIL - 600N
Physical Properties (Waxy) Paraffinic Feed Extract Oil
Density 15C 0.9327 0.9670
Viscosity, cSt @ 100C 17.7 42.2
Refractive Index @ 75C 1.5036 1.5511
Aniline Point, C 90.3 44.0
Pour Point, C 48.0 6.0
Sulfur, wt.% 1.7 3.0
Dewaxed Viscosity Index 39 N/A*
@ -9 Pour
Compositional Properties
(Waxy)
Saturates, wt.% 42 17
Polars & Aromatics, wt.% 58 83
*Viscosity Index of coproduced raffinate at -9°C pour is 100

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The resultant mixture is then subjected to a solvent extraction using
aromatic extraction solvents such as those previously described in connection
with
obtaining the aromatic extract oil for blending, but under generally milder
conditions.
Thus, for example, in extracting the blended feed the ratio of solvent to
blended feed is
generally in the range of about 0.5:1 to about 3:1 and the extraction is
conducted at a
temperature in the range of about 50°C to about 150°C and the
extraction solvent
contains water in the range of about 1 vol% to about 20 vol%; and preferably
greater
than about 5 vol% to produce a raffinate.
The resultant raffinate is then subjected to a hydrotreating step in a single
hydrotreating stage which is maintained at a temperature in the range of about
275°C to
about 375°C and preferably within the range of 340°C to
365°C at a hydrogen partial
pressure in the range of about 300 to about 2500 psia and preferably from 500
to 1200
psia. Hydrotreating is conducted at a liquid hourly space velocity in the
range from
about 0. 1 to about 2.0 v/vlhour and preferably from 0.5 to 1.0 v/v/hour.
The hydrotreating is effected conventionally under hydrogen pressure and
with a conventional catalyst. Catalytic metals such as nickel, cobalt,
tungsten, iron,
molybdenum, manganese, platinum, palladium, and combinations of these
supported on
conventional supports such as alumina, silica, magnesia, and combinations of
these
with or without acid-acting substances such as halogens and phosphorous may be
employed. A particularly preferred catalyst is a nickel molybdenum phosphorus
catalyst supported on alumina, for example KF-840.
An optional dewaxing step could be conducted on the paraffinic rich feed
or the hydrofinished product using catalytic dewaxing or alkane or ketone or
catalytic
dewaxing.