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Patented Nov. 26, 1946 I
TREATMENT OF mnpngnoips
Lawton A. Burrows, Woodbury,=N.‘J., 'assigno'r to .
E. I. duPont de Nemours & Company, Wilming- '
ton, Del., a corporation of Delaware
g‘ , .
No Drawing. , Application June V15, 1945‘,
Serial No. 599,745
6 Claims. (01. 19,6713)
This invention relates to a novel method of
treating and re?ning mineral oils and more par
perature of 120° F. was maintained, at which tem
perature complete solution had resulted.
ticularly to a method of dewaxing such oils.
solution was then allowed to cool for one hour at
The problem of separating wax-like constitu
a temperature of around 32-37 ° R, where precip
ents from mineral oils has assumed much im
itation of wax resulted. The solution was ?ltered,
portance to the petroleum industry in recent
and the wax removed was transferred to another
years. The methods proposed and applied for
vessel, from which the nitrocyclohexane was re
accomplishing this result have in general com
moved by evaporation. The ?ltrate was trans
prised (1) cooling of the liquid oil, with crystal
ferred to a ?ask and the nitrocyclohexane dis
lization of the wax at the low temperatures ob 10 tilled off under 15 mm. pressure. The pour point
tained, (2) the use of solvents for selective solu
‘of the recovered oil Was 45° F. The amount of
tion of: certain ingredients and the separation
wax separated from'the oil was 11.5%.
of the oil into two distinct layers, or (3) the com-'
A similar procedure in which use was made of
bination of selective solvents and refrigeration.
a two-component solvent commonly used in oil
The last method has been the one'most success
fully applied. In all procedures, the waxy con
15 re?ning gave a pour point for the recovered oil
of 50° F. and a wax removal of 10%.
stituents have been separated from the body of
Nitrocyclohexane from the process described is
the mineral oil and, where present, the solvent
recovered in large part and can be used repeat
has been removed. While various solvents have
edly in successive operations, without removal of
been used, the results have not been completely
small amounts of hydrocarbon. Eventually puri
satisfactory because of the dif?culty of ?nding a
?cation of the repeatedly used solvent may ‘be
solvent possessing all the desirable character
The employment of nitrocyclohexane for pur
An object of the present invention is a, new
poses of .wax removal has been emphasized in
and improved method of treating mineral oils and 25 the foregoing, and it is this use which is partic
separating various constituents, in order to obtain
ularly important. The invention will include,
a re?ned product. A further object is such a
however, selective separation of any ingredients
method, which employs for the purpose a solvent ,
by means of nitrocyclohexane. It may be de
of superior properties. A still further object is a
sired,'for example, to separate mineral oils into
method of dewaxing mineral oils. Additional ob
portions richer respectively in para?in or naph
jects will be disclosed as the invention is de
thenic hydrocarbons, and my invention is in
scribed more at length in the following.
tended to cover such a process. Moreover, in
I have found that the foregoing objects are
addition to the removal of waxes by refrigeration
attained when the mineral oil for treatment is
of the solution in nitrocyclohexane and precipi
admixed with nitrocyclohexane and maintained 35 tation of the Waxy constituents, the separation‘
at a sufficiently elevated temperature to assure
may be into two liquid layers, one higher than
substantial solution or miscibility, and the solu
the other in wax content, rather than separation
tion is then cooled to a temperature at which
of a. solid from a liquid. It will be understood, -‘
segregation into more than one portion results.
therefore, that the invention covers all proced
‘The segregated portions are separated and the ni 40 ures whereby selective extraction and concen
trocyclohexane recovered from the respective por
tration are effected by use of the solvent de
tions, preferably by distillation under reduced
pressure. In the dewaxing of oils, the wax por
Whereas, also, the example has cited
a single batch extraction of the wax content of
tion will ordinarily precipitate out in solid form
the oil, it will frequently be desirable to employ
on cooling and will be separated from the oil by 45 a multiple extraction process, wherein fresh sol_
?ltration, centrifuging, or like procedures.
vent is caused to obtain extractable material from
The‘ following will serve as a speci?c example
ra?inates from previous extractions. vIt will be
of a procedure for carrying out the invention.
This is, of course, merely illustrative and is not
to betaken as limiting in any way.
A sample of Pennsylvania wax distillate was
used, having a pour point of 105° F. and a viscos
ity of 60 Saybolt Universal seconds at 210° F.
The oil was mixed with nitrocyclohexane in the
proportion of 30 to 70 respectively, and a tem
appreciated that the process described is- an ef
fective method of decreasing the pour point of
50 oils.
Nitrocyclohexane is excellently adapted for use
‘in the dewaxing of oils because of its properties
as a solvent, being miscible in all proportions
with such other solvents as ethanol, ether, ace
55 tone, benzene, kerosene, and the like. While it
has been disclosed as the sole solvent in extras‘ '
tive dewaxing processes, it may if desired be used
in accompaniment with other solvents; such as,
nitrobenzene, benzene, and the like.
It will be understood, therefore, that I intend
to be limited only by the following claims.
I claim: I
1. The process of treating mineral oils and sep
arating various constituents therein contained,
which comprises mixing the mineral oil with ni
trocyclohexane and effecting substantial solution
therebetween, cooling the solution to a tempera
ture at which segregation into more than one
portion results, and separating said segregated
2. The process of claim 1, in which two layers
of liquid are formed on cooling of the solution.
3. The process of claim 1, in which solidi?ca
tion of a. portion of the mineral 011 takes place
on cooling.
4. The process of re?ning mineral oils and sep
aratlng wax therefrom, which comprises e?ect
ing substantial solution of said oil in nitrocyclo
hexane at a temperature su?iciently elevated
therefor, cooling said solution to a temperature
at which separation of the wax in solid form takes
place, and removing the separated solid from
contact with’ substantially the bulk of the solu
5. The method of claim 4, in which the nitro
cyclohexane is recovered from the respective liq
uid and solid separated portions.
6. The method of claim 4, in which the nitro
cyclohexane is removed from the respective por
tions by distillation under reduced pressure.
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