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reamed Feb. s, was
" 2,107,291
' UNITED STATES PATENT OFFICE .
2,107,291
TREATMENT OF HYDBOCARBON 01L
Seymour W. Fen-ls, Aidan, Pa” anignor to The
Atlantic Re?ning Company, Philadelphia, Pa»
a corporation of Pennsylvania
.
No Drawlnl. Allliucliion April 19, 1935,
'
Serial No. 17,262
'
20 Claims. (Cl- 196-13)
The present invention vrelates to the art of.
mineral oil re?ning, and has particular reference
to the separation of crude petroleum or petroleum
paramn base oils. The usual criteria 0! the 116-‘
gree'of paramnicity or naphthenicity of‘ an oil
are the viscosity-gravity constant and the vis-‘
products into fractions of different chemical com
5 position while of approximately the same distil
lation range.
In accordance with my invention, crude pe
troleum or petroleum products, particularly oils
of substantial viscosity, are separated into various
10 fractions by extraction with a mixture of sol
vents, and more particularly with selective sol
cosity index. ‘The viscosity-gravity constant is
vents such as nitrobenzene, nitrotoluene, benz
aldehyde, dichloro ethyl ether, pyridine, cresylic
acid and furfural, to which has been added a
1.3 polyhydroxy cyclic compound such as, for ex
ample, resorcinol, pyrocatechin, pyrogaiiol, and
the homologues thereof.
It is recognized in the art that mineral oils,
such as petroleum, comprise essentially a mixture
20 of hydrocarbons of various groups or homo
logous series of compounds, such for example, as
parailins of the general formula CnH2n+2, ole?nes
of the general formula C1IH27l, hydroaromatics
and polymethylenes of the‘ same empirical for
35 mula, and various other series of compounds of
chain and/or ring structures in which the hy
drogen to carbon ratio is less than in the fore
going series. A large number of individual com
pounds of each series and of differing boiling
points are present in petroleum.
The various types of crude petroleum, which
are generally classi?ed into three groups, namely,
pai'a?inic base, naphthenic or asphaltic base, and
mixed base, contain the various series of hydro
35 carbons mentioned heretofore in different pro
portions. For example, in the paraf?nic base
crude oils, such as those obtained from the oil
fields of Pennsylvania, there is a relatively high
proportion of hydrocarbons having a chain struc
40 lure and a high hydrogen to carbon ratio, where
as in the naphthenic or asphaltic base crude oils,
there is a relatively large proportion of hydro
carbons having ring structures and a low hydro
_ gen to carbon ratio. Mixed base crude oils, such
b as are obtained from the Mid-Continent oil ?elds,
contain hydrocarbons in proportions intermedi
ate between these two extremes.
_
The para?in base oils and their distillates are
said to be more para?inic than the mixed base
DU
oils and their distillates and these in turn are
more para?inic than the naphthene base oils and
a constant relating viscosity and speci?c gravity 5
and is described in an article entitled “The vis
cosity-gravity constant of petroleum lubricating
oils” by J. B. Hill and H. B. Coates which will
be found in vol. 20, page 641 et seq., of Industrial
and Engineering Chemistry. Viscous oils result- 10
ing from the distillation of Pennsylvania type
crudes have viscosity-gravity constants ranging
from about .805 to about .828, and in most in
stances are below .820. Those resulting from the
distillation of Mid-Continent crudes have vis- l6
cosity-gravity constants ranging from about .835
to about .855, whereas those from naphthenic
crudes are generally higher than .860. The vis
cosity index is a coe?lcient based on the change
of viscosity with temperature, and is described 20
by Dean and Davis in vol. 36, page 618 of Chem
ical and Metallurgical Engineering. The more
para?inic oils are characterized by low viscosity
gravity constants and high viscosity indices,
whereas the more naphthenic oils are character- 25
ized by higher viscosity gravity constants and
lower viscosity indices.
_
My invention is based upon the discovery that
oils containing both the para?inic series of hy
drocarbons and the various naphthenic series 30
may be fractionally extracted with a selective
solvent in admixture with a polyhydroxy cyclic
compound. The various series of hydrocarbons
possess a differential solubility in such solvent
mixture, the naphthenic hydrocarbons being as
much more soluble therein than the para?inic
hydrocarbons. By means of extraction with such
solvent mixture, it is therefore possible to e?'ect
a’partial separation of the naphthenic hydrocar
bons from the para?inic, and to obtain from an 40
oil containing both classes of hydrocarbons, an
oil which is much more para?inic than the origi
nal oil and one which is much more naphthenic.
By my invention, for example, it is possible to
produce an oil of the quality normally obtained 4°
from Appalachian crudes, from crudes of the
mixed base type from the Mid-Continent area
or from those of the naphthenic base type and,
conversely, to obtain oils from mixed base crudes 50
or para?inic base crudes such as are normally
obtained from the naphthenic oils of the Gulf
their distillates. Conversely the naphthene base
Coast area. In general, from oils from any source
oils are more naphthenic than the mixed base
there may be obtained by my process, oils which
are respectively more para?inic and more naph- 55
oils and these in turn more naphthenic than the
2
2,107,291
thenic than the oils normally obtainedfrom such
crystallize before separation of fractions can be
source by distillation.
e?ected. However, by adding to the selective
solvent, e. g., nitrobenzene, a‘ suitable quantity
of a polyhydroxy cyclic compound, for example
5% or 10% of resorcinol, I am able to treat in a
satisfactory manner, even the very 'asphalti
I
It has been known heretofore to separate hy
drocarbon oils into fractions by means of solvents
such as sulfur dioxide, furfural, vand others.
Such separation is accomplished by agitating the
oil with the solvent and bringing the mixture to
such a temperature, below the temperature of
complete miscibility of the oil and solvent, that
10 the mixture separates into two layers, one of
which is the undissolved and more para?inic por
tion of the oil containing some dissolved solvent,
and the other of which is solvent containing dis
solved naphthenic constituents of the oil. These
two layers are separated at this “separation tem
perature" and the solvent may subsequently be
removed from each. I have found it highly ad
vantageous to eil'ect such separation by employ
ing a mixture of a selective solvent and a polyhy
20 droxy
cyclic compound. In particular, the
aromatic nitro solvents, for example, nitroben
zene, are highly selective but usually require a
separation temperature below, for example, 60°
F., due to their relatively low miscibility tem
perature with the hydrocarbon oils. The sep
aration temperatures employed are, in general,
about 45° F. below the miscibility temperature of
the ‘oil and solvent. By employing a suitable
mixture of a selective solvent and a polyhydroxy
30 cyclic compound, I am able to separate hydro
carbon oils into fractions at temperatures con
siderably above those which could be employed
with the selective solvent alone. For example,
100 parts, by volume, of a dewaxed high viscosity
35 oil from Barber's Hill (Texas) crude oil was mixed
with 150 parts, by volume, of nitrobenzene, and
the miscibility temperature was found to be
104° F. In general, this would indicate that the
extraction should be carried out attemperatures
40 not higher than about,60° F. When 100 parts
of the same oil was admixed with 150 parts of a
solvent composed of 95% by weight of nitroben
zene and 5% by weight of resorclnol, the mis
cibilty temperature was found to be 138° F., indi
cating that an extraction could be carried out»
satisfactorily at a temperature of the order of 95°
F. When 100 parts of the same oil were mixed
with 150 parts of solvent composed of 90% by
weight of nitrobenzene and 10% by weight of
resorcinol, the miscibility temperature was found
to be 192° R, which would permit of extraction
at temperatures as high as about 150° F.
It will
be understood, of course, that the quality of the
undissolved or more parafiinic oil fraction pro
55 duced by means of the solvent mixture will fre
quently be somewhat lower than that of a similar
fraction produced with nitrobenzene alone. In
California oils.
'
In accordance with my invention, I ?rst mix
the oil to be treated in a suitable proportion of
a mixture of a selective solvent and a polyhy
droxy cyclic compound at a temperature such
that complete solution is e?ected and a homo
geneous liquid obtained. I then cool the solution
to a temperature. at which separation of the
liquid into a two-layer system will take place.
one layer will contain a relatively small amount
of the solvent dissolved in _the para?lnic portion
of the oil while the other layer will contain‘ the
more naphthenic portion of the oil dissolved in
the major quantity of the solvent. Or, I may
agitate the mixture of solvent and oil at tem
peratures at which the liquids are only partially
miscible, and thereby etl'ect solution of the naph
thenic portion of the oil in the solvent. In either
of the above procedures I may take advantage
of the principles of countercurrent extraction.
After the extraction proper, I eii’ect separation
of the two layers which form, by any suitable
procedure, as for example, by decantation.‘ I
then remove from each of the separated layers,
the portion of solvent which each contains, by
suitable procedure, such as by vacuum distilla
tion, thereby to obtain two oils of similar distil
lation ranges but of different chemical composi
tion and diiferent vphysical characteristics.
Before removing the solvent from the undis
10
solved or more para?lnic layer, I may add a
further quantity of the solvent mixture and re
peat the extraction, thereby to remove addi
tional naphthenic constituents from said layer.
The extraction step may be repeated any desired
number of times, each repetition producing an
oil of higher paraihnicity as evidenced by its
lower viscosity-gravity constant.
‘
A countercurrent relationship in these succes
sive extractions may be established in the con
ventional manner by employing the partially
spent solvent containing dissolved naphthenic oil
from the succeeding stages of the extraction sys
tem to extract additional quantities of oil in the
preceding stages. In the event that the miscibil
ity temperature of the oil with the selective sol
vent in the latter stages of the system is su?l
. ciently high, the polyhydroxy cyclic compound
may be introduced at any desired preceding stage,
in order to lessen or eliminate the refrigeration
required in the earlier stages.
general, greater yields are obtained and higher‘
Where substantial quantities of waxy hydro
operating temperatures may be employed when carbons belonging to the true para?ln series
60 a mixture of a selective solvent and a polyhydroxy
(CnH2n+2) are present, such hydrocarbons re
cyclic compound is utilized. In any event, an main in the undissolved or more para?lnic layer
economic balance must be struck between the
yield and quality of the refined oil, and the cost and may cause such layer ‘to be solid or semi
solid, after the removal of the solvent therefrom.
of producing the same.
'
In some cases, the extraction and separation of
65
Furthermore, in accordance with my inven
tion, I am able to separate hydrocarbon oils into the layers may be effected at temperatures above
fractions with my solvent mixture, which could the melting point of the waxy hydrocarbons, .so
that substantial entrainment of oil in the molten
not be economically treated with a selective sol
vent alone. For example, it is not practical to or liquid war is avoided. Such layer may be sep
arated into solid and liquid hydrocarbons by any
70 employ a solvent, such as nitrobenzene, in treat
ing very asphaltic oil stocks such as those derived of the well-known dewaxing processes such as by 70
from some California crude oils, for the reason
cold-settling, filtering, or by centrifuging.
that the miscibility temperature of the oil and
many instances it may be advantageous to dewax
the oil prior to extraction. However, it is to be
understood that in accordance with my inven
solvent is very low, excessive refrigeration is re
75 quired, and in certain cases the nitrobenzene may
75
3.
aroma
tioh, dewaxing may ~be eifected either~ prior or
subsequent to extraction.
I
'
My invention will be further understood from
the following speci?c examples:
I. 100 parts by volume of a residuum from a
Gulf Coast crude oil having a viscosity of 518
seconds Saybolt universal at 210° F., a speci?c
gravity of 0.9759 at 60° F., and a viscosity-grav
ity constant of 0.894, was mixed with 200 parts
by volume of a solvent consisting of 90% by
weight of nitrobenzene and 10% ,-by weight of
pyrocatechin, and heated to slightly above the
temperature of complete miscibility, i. e., about
143° F. The homogeneous liquid which resulted
15 was cooled, with ‘agitation, to 95° F. and allowed
to settle, whereupon a two-layer system was
formed. After separation, the layers were each
freed of solvent by vacuum distillation. The
resulting undissolved oil fraction comprising
20 35.0% of the stock had a viscosity of 208 sec
onds Saybolt universal at 210° F., a speci?c grav
ity of 0.9188, and a viscosity-gravity constant of
0.833. The initial Gulf Coast residuum had a
miscibility temperature of 91° F; with nitro
benzene alone, and would have required extrac
tion at temperatures below 46° F., to effect a sat
isfactory separation of oil fractions.
.
II. 100 parts by volume of a Barber's I-Iill lu
bricating oil distillate having a viscosity of 110
30 seconds Saybolt universal at 210° F., a speci?c
gravity of 0.926 at 60° F., and a viscosity-gravity
constant of 0.854, was mixed with 200 parts by
Volume of a solvent consisting of 90% by weight
of nitrobenzene and 10% by weight of pyrogallol,
and heated to slightly above the temperature of
complete miscibility, i. e., about 185° F.
there may be obtained oil fractions which are
respectively more para?inic and more naphthenic
than the original oil. By repetition of the ex
traction process upon the undissolved fraction,
oils of even greater para?inicity will result. The
quantity of polyhydroxy cyclic compound to be ‘
employed in conjunction with the selective sol
vent will vary, depending upon the character of
the selective solvent, the temperature at which
the extraction is to be carried out, and the qual 10
ity of re?ned oil desired. In general, the quan
tity of polyhydroxy cyclic compound employed
‘will be of the order of from about 5% to about
10% by weight of the selective solvent. How
ever, more or less of the polyhydroxy compound
may be employed, depending upon the tempera
ture at which the extraction is. to be carried out.
While, in the above examples, I have shown
the use of. a selective solvent such as nitrobenzene
in admixture with various polyhydroxy cyclic
compounds, I do not intend to limit myself there
to, but may employ various selective solvents in
conjunction with the polyhydroxy cyclic com- '
pounds. The following table illustrates the effect
upon the miscibility temperature of oil with vari
ous selective solvents to which have been added
small quantities of a polyhydroxy cyclic com
pound. _ The miscibility temperatures were deter
mined by heating 1; volume of lubricating oil
30
stock with 2 volumes of selective solvent or sol
vent mixture, to a temperature such that com
plete solution of oil and solvent was obtained,
and thereafter cooling the solution until the
formation of a haze was noted, thus indicating
the separation of two liquid phases.
The
homogeneous liquid which resulted was cooled,
with agitation, to 158° F. and allowed to ‘settle,
whereupon a two-layer system formed. After
(0 separation, the layers were each freed of solvent
by vacuum distillation. The resulting undis~
solved fraction comprising 47.7% of the stock
had a viscosity of 94 seconds Saybolt universal
at 210° F., a specific gravity of 0.9088, and a vis
cosity-gravity constant of 0.834. The initial lu
bricating oil distillate had a miscibility tempera
ture of 110° F. with nitrobenzene alone, and
a viscosity-gravity constant of 0.857 was contin
55 uously extracted in a 3-stage countercurrent sys
tern with 114% by volume of a solvent consisting
of 90% by weight of nitrobenzene and 10% by
weight of resorcinol, at a temperature of about
149° F., or~about 49° F. below the temperature
of miscibility, i e., 198° F. The resulting un
dissolved oil fraction, after removal of solvent
by weight pound percent temp
by weight
°F.
increase
°F.
40
100
90
100
Do ________ ._
._
90
Benzaldehyde _____ ._
100
Doz ___________ __
'90
.............. __
Resorcinol 10
______________ __
Resorcinol 10
.............. __
Resorcinol i0
110
________ -_
201
01
77
........ __
170
93
103
________ __
201
98
143
_______ . .'_
BB’ dichloro ethyl
ether _____________ _ _
100
90
100
90
would have required extraction at temperatures
below 66° F., to effect a satisfactory separation of
50 oil‘ fractions.
III. A Gulf Coast lubricating oil stock having
a viscosity of 7'? seconds Saybolt universal at
210° F., a speci?c gravity of 0.923 at 60° F., and
Perccn t Polylhydroxy
bMlistciMis'cihil
eye it: comii.y my
amp
-
semen“ Solvent
mo
9O
.............. _ _
Resorcinol 10
______________ _.
Resorcinol i0
______________ __
Resoreinol 10
221
78
225
________ -_
289
64
103
......... __
237
74
My process is practically independent of the
particular nature or source of the crude oil or
oil fraction to be extracted. There may be pro
duced by my process oil products of desired char
acteristics from oil which by distillation will not Ca Ca
produce such products. Moreover, it will be
understood, that in accordance with my inven
tion, an important aspect thereof is the increase
of the miscibility temperature of the oil and
naphthenic solvent by the presence of the poly 60
hydroxy cyclic compound regardless of whatever,
by vacuum distillation, comprised 70% of the
oil stock charged to the extraction system. This
if any,.selective action such compound may have
re?ned oil fraction had a viscosity of 69 seconds
When, in the appended claims, oil is referred
to as being “viscous”, it is to be understood that
the oil is of substantial viscosity, i. e., of the order
of 50 seconds Saybolt universal at 100° F., or
Saybolt universal at 210° F., a speci?c gravity
of 0.9024, and a viscosity-gravity constant of
0.833.
The initial lubricating oil stock had a
miscibility temperature of 104° F. with nitro
benzene alone, and would have required extrac
70 tion at temperatures below 60° F., to e?ect a sat
isi’actory separation of the oil into fractions.
From the above examples, it will be noted that
by extraction of an oil with a solvent mixture
comprising a selective solvent, such as nitro
75 benzene and a polyhydroxy cyclic compound,‘
upon the oil.
more.
What I claim is:
1. In the art of re?ning mineral oils, the
process which comprises separating a viscous oil
containing paraf?nic and naphthenic hydro
carbons into fractions respectively richer in
para?inic and naphthenic compounds by extract
ing said oil with a selective solvent for naph
75
4
2,107,291
thenic hydrocarbons, said solvent containing a
polyhydroxy cyclic compound in suiilcient quan—
tity to substantially increase the miscibility tem
perature of said selective solvent with said oil.
2. In the art of refining mineral ‘oils, the
process which comprises adding to a viscous oil
thereof into contact with a selective solvent for
naphthenic hydrocarbons, said solvent contain
ing a polyhydroxy cyclic compound in sumcient
containing para?lnic and naphthenic hydrocar
quantity to substantially increase the miscibility
bons a selective solvent for naphthenic hydro
carbons, said solvent containing a polyhydroxy
cyclic compound, in. su?lcient quantity to sub
oil, thereby partially dissolving the oil, separat
- stantially increase the miscibility temperature
oi’ said selective solvent with said oil, heating the
mixture to such temperature as to effect solu
tion, cooling the solution ‘to form a two-layer
15
7. The method for producing paramnic lubri
cating oil from vmixed base crude; which com
prises distilling the crude and bringing a portion
system, and separating the upper layer from the
lower layer.
3. In the art of re?ning mineral oils, the
temperature of said selective solvent with said
ing the solution of oil so treated, and removing
the solvent from the treated oil.
8. In the art of. re?ning mineral lubricating oil
containing pa‘railinic and naphthenic hydrocar
bons, the step of‘ fractionally extracting the oil
with a selective solvent for naphthenic hydro 15
carbons, said solvent containing a polyhydroxy >
a cyclic compound in suil‘icient quantity to sub
process which comprises adding to a viscous 011
stantially increase the miscibility temperature of
containing para?lnic and naphthenic hydrocar
said selective solvent with said oil, to elect a
separation of fractions respectively richer in
bons a selective solvent fornaphthenic hydro
carbons, said solvent containing a polyhydroxy
cyclic compound .in su?lcient quantity to sub
‘ stantially increase the miscibility temperature of
said selective solvent with said oil, heating the
mixture to such temperature as to effect solu
tion, cooling the solution to form a two-layer
system, removing the lower layer, and similarly
re-treating the upper layer with said solvent mix
ture.
'
'30 ,' 4. In the art of re?ning mineral oils, the
process which comprises bringing a viscous
mineral oil containing para?inic and naphthenic
hydrocarbons into contact with a selective sol
vent for naphthenic hydrocarbons, said solvent
containing a polyhydroxy cyclic compound in
suiilcient quantity to substantially increase
the miscibility temperature of said selective sol
vent with said oil, thereby to e?’ect'solution of a
portion richer in naphthenic hydrocarbons in the
40 solvent
mixture, separating the solution so
formed from the remainder of the oil, and re-'
moving the solvent from both portions of. the
oil, thereby to obtain fractions of the oil respec
tively richer in para?lnic and naphthenic hydro
carbons.
'
'
para?lnicand naphthenic compounds.
I
9. The process of treating a viscous fraction of
a crude oil of one type containing parailinic‘ and
naphthenic hydrocarbons to procure a fraction
having the quality of va corresponding fraction 25
of a crude oil of di?erent type having a greater
content of. parai?nic hydrocarbons, which com
prises extracting the viscous fraction with a
- selective solvent for naphthenic hydrocarbons,
said solvent containing a polyhydroxy cyclic 30
compound in su?icient quantity to substantially'_
increase the miscibility temperature of said
selective solvent with said oil fraction, and sepa
rating the oil so treated into portions respectively
richer in para?inic and naphthenic hydrocar 35
bons.
.
10. The process of treating a viscous fraction
of a mixed base crude oil to procure a fraction
having the quality of a corresponding traction of
a parafiinic base crude, which comprises extract 40
ing the viscous fractionwith a selective solvent
for naphthenic hydrocarbons, said solvent con
taining a polyhydroxy cyclic compound in sum
cient quantity to substantially increase the mis
cibiiity temperature of said selective solvent with 45
5. The process for separating viscous mineral
said oil fraction, and separating the oil so treated
oils containing para?inic and naphthenic hydro
carbons into fractions, which comprises bringing
into portions respectively richer in paraillnic and
the oil into contact with a selective solvent for
11. In the art of. re?ning mineral oils, the
process which comprises bringing a viscous
hydrocarbon oil of a quality other than that of
a Pennsylvania type viscous oil, and containing
paraiilnic and naphthenic components into inti
naphthenic hydrocarbons, said solvent contain
ing a polyhydroxy cyclic compound in su?icient
quantity to substantially increase the miscibility
temperature of said selective solvent with said oil,
thereby to effect solution of a portion of the oil
richer in naphthenic hydrocarbons in the sol
vent mixture, separating the solution so formed
from the remainder of the oil, and distilling the
solvent from‘ both of the portions of the oil,
thereby to obtain fractions of the oil respectively
60 richer in para?inic and naphthenic hydrocar
bons.
-
-
6. In the art of re?ning mineral oils, the
process which comprises bringing‘a viscous min
eral oil containing paraiiinic and naphthenic
hydrocarbons into contact with a selective sol
10'
._
naphthenic compounds.
_
mate contact with a selective solvent for naph
thenic hydrocarbons, said solvent containing a
polyhydroxy cyclic compound in sufficient quan
tity to substantially increase the miscibility. tem
perature of said selective solvent with said oil,
thereby to dissolve from the ‘oil substantial
amounts of its naphthenic components, there
after removing the solvent mixture and oil dis
solved therein from that portion of the oil which
remains undissolved, thereby to produce an oil
such as is normally obtained from Pennsylvania
type crude by distillation.
vent for naphthenic hydrocarbons, said solvent
containing a polyhydroxy cyclic compound in
sufficient quantity to substantially increase the
miscibility temperature of said selective solvent
12. In the art of re?ning mineral oils,‘ the
process which comprises separating a viscous oil
with said oil, ther'eby to effect solution of a por
a?inic and naphthenic compounds by extracting 70
hydroxy cyclic compound.
tion richer in naphthenic hydrocarbonsrin the
solvent mixture, separating the solution so
formed from the remainder of the oil, and re
treating the oil remaining with
75 amounts of the solvent mixture.
additional
containing para?inic and naphthenic hydrocar
bons into fractions respectively richer in par
said oil with nitrobenzene containing a‘ poly
13. In the art of re?ning mineral oils, the
process which comprises bringing a-‘mineral oil
containing para?inic and naphthenic hydrocar 75
5
2,107,291
bons into contact with nitrobenzene containing a
polyhydroxy cyclic compound thereby to e?ect
_ solution of a portion richer in naphthenic hydro-y
carbons in the solvent, separating the solution
so formed from the remainder of the oil, there
by to obtain fractions of the oil respectively
richer in para?inic and naphthenic hydrocar
bone.
14. The process of treating a viscous fraction
of a crude oil of one type containing para?inic
and naphthenic hydrocarbons to procure a frac
tion having the quality of a corresponding frac
tion of a crude oil of different type having a
16. In‘ the process of decreasing the viscosity
gravity constant of a viscous mineral oil, the step
of extracting the oil with a solvent mixture‘ com
prising an aromatic nitro compound and a poly
hydroxy cyclic compound.
17. In the process of decreasing the viscosity
gravity constant of a viscous mineral oil, the
step of extracting the oil with nitrobenzene con
taining resorcinol.
18. In the processof decreasing the viscosity 10
gravity constant of a viscous mineral oil, the step
of extracting the oil with nitrobenzene contain
ing pyrogallol. ‘
_
'
comprises extracting the viscous fraction with
nitrobenzene containing a polyhydroxy cyclic
19. In the process of decreasing the viscosity
gravity constant of a viscous mineral oil, the step
of extracting the oil with nitrobenzene contain
compound, and separating the oil so treated into
ing pyrocateqhin.
greater content of para?inic hydrocarbons, which
portions respectively richer in para?inic and
naphthenic hydrocarbons.
15. The method for producing a para?inic
lubricating oil from a mixed base crude oil, which
comprises distilling the crude and bringing a por
tion thereof into contact with nitrobenzene con
taining a polyhydroxy cyclic compound, thereby
partially dissolving the oil, separating the solu
tion of the oil so treated,_and removing the sol
vent from the treated oil.
Y
'
20. A method for increasing the miscibility
temperature of a selective solvent with a hydro
carbon oil, which comprises adding to said sol 20
vent for naphthenic components a polyhydroxy
cyclic compound completely soluble therein and
capable of increasing to substantial extent the
miscibility temperature of the solvent with the
oil.
>
SEYMOUR W. FERRIS.
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