U.S. patent number 3,639,229 [Application Number 05/050,976] was granted by the patent office on 1972-02-01 for refining of used lubricating oils.
This patent grant is currently assigned to Esso Research and Engineering Company. Invention is credited to Darrell W. Brownawell, Remi H. Renard.
United States Patent |
3,639,229 |
Brownawell , et al. |
February 1, 1972 |
REFINING OF USED LUBRICATING OILS
Abstract
Used lubricating oils, particularly those containing additives
such as V. I. improvers, dispersants and the like, are reclaimed by
a preliminary treat with a C.sub.4 to C.sub.5 aliphatic alcohol,
which causes the separation of a layer of sludge which contains
polar additives and oxidation products. The desludged oil is then
subjected to conventional lubricating oil refining steps such as
treatment with fuming sulfuric acid followed by neutralizing,
washing, and clay treating steps. Alternatively, the desludged oil
is subjected to a hydrogenation treatment rather than the sulfuric
acid treatment. Extraction with phenol, furfural, etc. can also be
included, as well as redistillation or fractionation. Advantages
over prior art oil reclaiming processes include higher yields of
finished reclaimed oil, the formation of appreciably less byproduct
sludge, and the obtaining of a more oxidation-resistant reclaimed
oil. BACKGROUND OF THE INVENTION It is well known in the prior art
to reclaim used lubricating oils by various methods, all of which
employ some means for removing undesirable constituents such as
oxidation products. A typical process will include the steps of
heating the oil and allowing separated matter to settle out,
subjecting the supernatant oil to an acid treating step and
removing from the oil the resultant acid sludge, then neutralizing
the oil with a basic material, followed by some form of clay
treating and filtration. Some reclaiming processes omit the acid
treating step and substitute a more severe clay treatment, which
may or may not be preceded by heating, fractionation or
distillation steps. In all of the prior art oil reclaiming
processes there is a serious problem in disposing of sulfuric acid
sludge and/or sludgy clay from the clay treating steps. In recent
years, with the realization that pollution problems are increasing,
there has been a demand for a more efficient oil reclaiming process
in which there will be a minimum of sludge, contaminated clay, and
the like to be disposed of. Furthermore, with the more extended use
of dispersants in lubricating oils the cost of reclaiming used oil
has increased. Rising costs of oil reclaiming have discouraged a
number of rerefiners from continuing in the oil reclaiming
business. However, because of the increased emphasis on reduction
of pollution, the disposal of used oil in sewers and rivers or by
dumping on open ground has been at least discouraged if not legally
barred. Thus, there is now a need for new reclaiming processes
which will allow the production of reclaimed lubricating oils at
reduced cost and increased yields.
Inventors: |
Brownawell; Darrell W. (Scotch
Plains, NJ), Renard; Remi H. (North Brunswick, NJ) |
Assignee: |
Esso Research and Engineering
Company (N/A)
|
Family
ID: |
21968638 |
Appl.
No.: |
05/050,976 |
Filed: |
June 29, 1970 |
Current U.S.
Class: |
208/181;
208/184 |
Current CPC
Class: |
C10M
175/005 (20130101) |
Current International
Class: |
C10M
175/00 (20060101); C10g 027/100 () |
Field of
Search: |
;208/181,180,182,183,179,95,88,211,88,96,337,266,270,271 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gantz; Delbert E.
Assistant Examiner: Nelson; J.
Claims
What is claimed is:
1. In a process for reclaiming a used lubricating oil wherein the
used oil is stripped of water and volatile constituents and
subsequently subjected to a conventional lubricating oil refining
step, the improvement which comprises removal of sludge components
of the used oil by treating the oil with from 30 to 200 volumes of
a C.sub. 4 or C.sub. 5 aliphatic alcohol per 100 volumes of used
oil following the stripping step and prior to the conventional
refining step.
2. Improvement as defined by claim 1 wherein said alcohol is normal
butanol.
3. Improvement as defined by claim 1 wherein said alcohol is mixed
with a minor proportion of a C.sub. 4 to C.sub. 6 aliphatic
hydrocarbon to facilitate precipitation of sludge.
4. Improvements as defined by claim 3 wherein said hydrocarbon is
pentane.
5. Improvement as defined by claim 1 wherein said subsequent
refining step includes acid treating.
6. Improvement as defined by claim 1 wherein said subsequent
refining step includes treatment with hydrogen.
7. Improvement as defined by claim 1 wherein said subsequent
refining step includes solvent extraction with phenol.
8. An improved process for reclaiming a used hydrocarbon
lubricating oil containing additives including V.I. improvers and
dispersants which includes the steps of distilling volatile
substituents from said oil, mixing 1 volume of the resulting
stripped oil with from one-third to 2 volumes of a mixture of
normal butanol and normal pentane whereby a sludge layer is caused
to precipitate from said oil, separating said sludge from said oil,
and thereafter subjecting said oil to a treatment with fuming
sulfuric acid followed by neutralizing the acid treated oil.
9. Process as defined by claim 8 which includes a final clay
treating step.
10. An improved process for reclaiming a used hydrocarbon oil
containing additives including V.I. improvers and dispersants which
includes the steps of distilling volatile constituents from the
oil, treating the stripped oil with a mixture of normal butanol and
normal pentane whereby a sludge layer is formed, separating said
sludge from said oil, and subjecting the sludge-free oil to a
hydrogenation step.
Description
DESCRIPTION OF THE INVENTION
In accordance with the present invention, it has been found that
the reclaiming of used lubricating oils can be greatly improved if
the used oil is first subjected to a precipitation step wherein an
oxygenated polar liquid is used to bring about the precipitation of
sludge, polymeric materials and the like. The precipitated material
contains useful components as will hereinafter be explained. The
oxygenated material used in this invention is an aliphatic
monohydric alcohol of from 4 to 5 carbon atoms. Alcohols of from 1
to 3 carbon atoms are not miscible with the oil and do not bring
about precipitation of polymers and sludge. Likewise diols
including 1,3-ethanediol, 1,4 -butane diol, and 1,5-pentane diol
are partly miscible with used oil and do not induce precipitation
of polymers and sludge. The preferred precipitation agent is normal
butanol. Other effective alcohols include secondary butyl alcohol,
isobutyl alcohol, and isoamyl alcohol, and mixtures of such
alcohols.
In conducting the precipitation step of the process of this
invention the used oil is mixed with from about one-third to twice
its volume of the precipitating alcohol; preferably about equal
volumes of used oil and alcohol are employed. The precipitation is
normally carried out at ambient temperatures, e.g., from about
about 60.degree. to 100.degree. F. Precipitation does not occur
immediately and will usually require from about 12 to 24 hours to
complete. Separation can be improved by centrifuging the mixture of
oil and alcohol, as for example, from 10 to 30 minutes at 700 -800
g's. Precipitation can be facilitated by employing a small quantity
of a C.sub.4 to C.sub. 6 aliphatic hydrocarbon, along with the
alcohol. This will usually be about 5 to 30 volumes of hydrocarbon
per 100 volumes of the alcohol, e.g., from about 10 to 25 parts of
pentane for each 100 parts of the alcohol. The pentane can be
normal pentane or mixed pentanes. Hexane could also be used as well
as mixed pentanes and hexanes. While butane is normally too
volatile its use can be made possible with pressure equipment. In
most instances pentane will be preferred.
Depending on the starting used oil, the precipitate obtained after
settling and/or centrifuging will amount to about 3 to 8 percent of
the used oil. The oil separated from the precipitated sludge can
then be subjected to acid and clay treatment or to a hydrogenation
treatment as shown in the examples. The separated oil can
additionally, or alternatively, be subjected to other conventional
lubricating oil refining steps, including solvent refining, e.g.,
extraction with phenol or furfural or the like, redistillation,
etc. Another alternative, if the oil reclaiming plant is part of a
conventional petroleum refinery, involves blending the separated
oil, obtained in the sludge precipitation steps of this invention,
with the usual lubricating oil fraction obtained in the
distillation of a crude oil, to be subsequently handled as part of
the freed stream sent to the lubricating oil section of the
refinery.
In some cases, when the used oil is subjected to the precipitation
step with C.sub. 4 to C.sub. 5 aliphatic alcohol, three layers are
formed, the bottom layer being sludge, the middle layer being a
viscous material which contains viscosity index improvers, and a
top oily layer containing recoverable lubricating oil. It is
feasible to reclaim and reuse the viscosity index improver that is
present the the middle layer. In other instances there will be only
two layers, in which case the viscosity index improver of the used
oil will come out with the sludge layer. The three-layer separation
appears to occur most often if the viscosity index improver is of
the polyisobutylene type. In the case of two layer separation
wherein the viscosity index improver tends to come out with the
sludge, and recovery of viscosity index improver therefrom is not
economically feasible, the viscous sludge layer could find use as a
rubber extender oil or as a component of newspaper printing
ink.
The nature of this invention and the manner in which it can be
practiced will be more fully understood from the following
examples, which include a preferred embodiment.
EXAMPLE 1
One hundred volumes of a sample of used crankcase oil containing
conventional additives, including V.I. improvers, was heated at
190.degree. C. to remove gasoline components and water, giving 97
volumes of stripped used oil. To this were added 78 volumes of
normal butyl alcohol and 19 volumes of pentane. After settling and
centrifuging, three distinct layers were formed, the bottom layer
being sludge, the middle layer being a viscous layer and the top
layer being an oily layer. The oily layer contained 92 volumes of
oil, 73 volumes of butanol and 18 volumes of pentane.
The oily layer was subjected to a distillation to recover the
pentane and normal butanol for recycle to the process, leaving 92
volumes of oil as bottoms. The 92 volumes of oil were then treated
with 14 volumes of fuming sulfuric acid (containing 20 weight
percent SO.sub. 3 ) causing the formation of 25 volumes of sludge
and 70 volumes of acid treated oil. The acid treated oil was
separated from the sludge and neutralized with 50 volumes of an
aqueous solution containing 10 percent (by weight) of sodium
carbonate. After the pH of the water layer reached a value of
between 7 and 8, eight volumes of isopropyl alcohol were added to
the blend. The purpose of this step was to neutralize the residual
acidity in the oil resulting from the sulfuric acid treat and to
extract the sodium sulfonates resulting from this
neutralization.
The mixture of oil, isopropyl alcohol and sodium carbonate solution
was allowed to settle, giving three layers. The bottom layer
contained the inorganic salts e.g., sodium carbonate and sodium
sulfate, dissolved in water diluted with some isopropyl alcohol.
The second layer contained the sodium sulfonates dissolved in
isopropyl alcohol diluted with some water. The top layer was the
neutralized oil diluted with some isopropyl alcohol and water.
Then the oil was stripped at 140.degree. C. and 15 millimeters
mercury pressure and yielded 61 weight percent of reclaimed oil
based on the amount of oil at the beginning of the process. The
ASTM color of this reclaimed oil was 3.5. Further improvement in
color was obtained by subjecting the oil to a clay treatment in
which 100 parts of oil were percolated for 45 minutes at
130.degree. C. with 5 parts by weight of Attapulgus clay. The
operation was followed by a filtration to separate the oil from the
clay.
The above steps of the reclaiming process and the products of each
of the steps are outlined in table I which follows: ##SPC1##
EXAMPLE 2
Another portion of the used oil described in example 1 was
subjected to the stripping and normal butanol precipitating steps
therein described. Portions of the thus treated oil were then
subjected to a hydrogenation treatment at various temperatures and
pressures using a nickel hydrogenation catalyst (Harshaw Ni-0104T).
In each case, 136 grams of the treated used oil and 34 grams of
catalyst were placed in a 300 milliliter high pressure cell and the
cell was then purged with nitrogen before the hydrogenation
treatment began. In each run hydrogenation was conducted for 18
hours. The total hydrogen absorbed was computed from a record of
the hydrogen that had been added to the high pressure cell. The
results obtained are shown in table II which follows: ##SPC2##
COMPARATIVE EXAMPLE
A portion of the used oil described in example 1 was stripped of
water and gasoline in the same manner as described in example 1.
Then the oil was treated with 15 vol. percent of fuming sulfuric
acid (20 percent SO.sub. 3 ), the temperature being maintained
below 110.degree. F. Resulting acid sludge was separated from the
product and the acid treated oil was then neutralized with a
mixture of isopropyl alcohol and 10 percent aqueous sodium
carbonate solution, the amount of alcohol being about 7 weight
percent based on the amount of used oil before stripping, and the
amount of sodium carbonate solution being approximately 50 weight
percent of the amount of starting oil. Three layers were formed,
one containing inorganic salts dissolved in a water-rich phase, one
containing sulfonates and the remaining one consisting of
neutralized oil. The oil then was stripped at 140.degree. C. and 15
millimeters mercury pressure and yielded 58 weight percent of
reclaimed oil based on the amount of oil at the beginning of the
process. In this example the amount of sulfuric acid sludge formed
was about 32 weight percent based on the starting oil, whereas in
example 1, using the process of the present invention, the amount
of sulfuric acid sludge formed was only 23 weight percent based on
the starting oil.
Inspection data of the reclaimed oil obtained in this comparative
example are compared with those of the reclaimed oil obtained in
example 1, in the following table III. ##SPC3##
The table also gives inspection data for typical refined
lubricating oil base stocks of about 150 and 200 SUS viscosity,
respectively, at 100.degree. F. These data show that the rerefined
oil obtained in accordance with the present invention had
properties that were comparable with those of a conventionally
refined lubricating oil and that were somewhat superior to those of
the oil reclaimed by conventional treatment with sulfuric acid
alone.
The foregoing examples demonstrate that the present invention
provides an improvement in the art of reclaiming used lubricating
oil wherein high quality lubricating oil can be obtained along with
useful byproducts heretofore discarded in the prior art reclaiming
processes. At the same time there is less acid sludge to be
disposed of.
It is, of course, not intended that this invention be limited in
any way by the specific examples, as numerous modifications thereof
are possible without departing from the scope of the invention as
defined by the appended claims.
* * * * *