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Патент USA US2115704

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Patented May 3, 1938
2,115,704
UNITED STATES PATENT oFFIcE
2,115,704
_ TREATMENT OF HYDROGARBON OILS
‘Eugene R. Browns'combe, Aidan, Pa., assignor to
The Atlantic Re?ning Company, Philadelphia,
*
Pa., a corporation of Pennsylvania
No Drawing. Application April 25, 1925,
Serial No. 18,261
4 Claims.
(Cl. 196-13)
‘The present‘ invention relates to the art of min—
eral oil re?ning, and has particular reference to
the separation of crude petroleum or petroleum
gree of paraf?nicity or naphthenicity of an oil
are the viscosity-gravity constant and the vis—
cosity index. The viscosity-gravity constant is a
products into fractions of different chemical com
position while of approximately“ the‘same distil
and is described in an article entitled “The vis- 5
lation range.
‘
‘
cosity-gravity constant of petroleum lubricating
‘
In accordance with my invention, crude petro
leum or'petroleum products, particularly oils of
substantial viscosity, are separated into various
10 fractions by extraction with a mixture of solvents,
and more particularly with selective solvents such
as ‘nitrobenzene, nitrotoluene, benzaldehyde, di
chloro ethyl ether, cresylic acid and furfural, to
which has been added an organic acid anhydride
ll such as, for example, acetic, succinic, maleic,
phthalic anhydrides, and the homologues‘there
of.
‘
constant relating viscosity and speci?c gravity
,
‘It is recognized in the art that mineral oils,
such as petroleum, comprise essentially a mixture
26 of hydrocarbons of various groups’ or homologous
series of compounds, such for example, as paraf
?ns of‘ the'general formula CnH2n-I-2, olefines of
the general formula CnHZn, hydroaromatics and
polymethylenes of the same empirical formula,
25 and ‘various other series of compounds of chain
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
ing from the distillation of Pennsylvania type 10
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 viscos
ity-gravity constants ranging from about .835 15
to about .855, whereas those from naphthenic
crudes are generally higher than .860. The vis
cosity index is a. coef?cient based on the change
of viscosity with temperature and is described by
‘Dean and Davis in vol. 36, page 618 of Chemical 20
and Metallurgical Engineering. The more paraf
?nic oils are characterized by low viscosity-grew
ity constants and high viscosity indices, whereas
the more naphthenic oils are characterized by
higher viscosity-gravity constants and lower vis- 25
and/or ring structures in which the hydrogen to
cosity indices.
carbon ratio is less than in the foregoing series.
A large number of individual compounds of each
My invention is based upon the discovery that
oils containing both the para?inic series of hy
drocarbons and the various naphthenic series
series and of differing boiling points are present
‘
30 in‘ petroleum.
The various types of crude petroleum, which are
generally classi?ed into three groups, namely,
paraf?nicbase, naphthenic or asphaltic base, and
mixed base,'contain the Various‘series of hydro
'
may be fractionally extracted with a selective sol- 30
vent in admixture with an organic acid anhydride.
The various series of hydrocarbons possess a dif
ferential solubility in such solvent mixture, the
naphethenic hydrocarbons being much more sol
35 carbons mentioned heretofore in different propor- ‘ uble therein than the paraf?nic hydrocarbons. By 35
tions. For example, in the‘para?inic base crude
oils, such as those obtained ‘from the oil ?elds
of Pennsylvania, there is a relatively high propor
tion of hydrocarbons having a chain structure
40
means of extraction with such solvent mixture, it
is therefore possible to effect a partial separa~
tion of the naphthenic hydrocarbons from the
and a high hydrogen to ‘carbon ratio,v whereas
in the, naphthenic or asphaltic base crude oils,
para?inic, and to obtain from an oil containing
both classes of hydrocarbons, an oil which is
much more para?inic than the original oil and
there is a relatively large proportion of hydrocar~
bons having ring structures and a low hydrogen
one which is much more naphthetic. By my in
vention, for example, it is possible to produce an
to carbon‘ ratio. Mixed base crude oils, such as
are obtained from the Mid-Continent oil ?elds,
contain hydrocarbons in proportions intermediate
between these two extremes.
‘ The paraflin base‘ oils and their distillates are
said to be more para?inic than the mixed base
50 oils and their distillates and these in turn are
more paraf?nic than the naphthene base oils and
their distillates. Conversely the naphthene base
oils ‘are more naphthenic‘ than the mixed base
oils and these in turn more naphthenic than the‘
55. paraffin base oils. ‘The usual criteria of the de
oil of the quality normally obtained from Appa
lachian crudes, from crudes of the mixed base 45
type from the Mid-Continent area or from those
of the naphthenic base type and, conversely, to
obtain oils from mixed base crudes or paraf?nic
base crudes such as are normally obtained from
the naphthenic oils of the Gulf coast area. In 50
general, from oils from any source there may be
obtained by my process, oils which are respec
tively more para?inic and more naphthenic than
the oils normally obtained from such source by
distillation.
_
55
2
2,115,704
It has been known heretofore to separate hy
solvent, e. g., nitrobenzene, a suitable quantity of
an organic acid anhydride, for example 5% or
10% of maleic anhydride, I am able to treat in a
satisfactory manner, even the very asphaltic
drocarbon oils into fractions by means of solvents
such as sulfur dioxide, iurfural, and others. Such
separation is accomplished by agitating the oil
California oils.
with the solvent and bringing the mixture to such
a temperature, below the temperature of com
In accordance with my invention, I ?rst mix the
oil to be treated with a suitable-proportion of a
mixture of a selective solvent and an organic acid
plete miscibility of the oil and solvent, that the
mixture separates into two layers, one of which
is the undissolved and more para?inic portion of
anhydride at a temperature such that complete
solution is effected and a homogeneous liquid ob 10
tained. I then cool the solution to a temperature
at which separation of the liquid into a two-layer
10 the oil containing some dissolved solvent and the
other of which is solvent containing dissolved
naphthenic constituents of the oil. These two
layers are separated at this “separation tempera
ture” and the solvent may subsequently be re
15 moved from each. I have found it highly advan
tageous to eifect such separation by employing a
system will take place. One layer will contain
a relatively small amount of the solvent mixture
dissolved in the paraf?nic portion of the oil,
while the other layer Will contain the more naph
thenic portion of the oil dissolved in the major
quantity of the solvent mixture. Or, I may
agitate the mixture of solvent and organic acid
anhydride with the oil at temperatures at which
mixture of a selective solvent and an organic acid
anhydride. In particular‘, the aromatic nitro
solvents, for example, nitrobenzene, are highly
20 selective but usually require a separation tem
perature below, for example, 60° F., due to their
relatively low miscibility temperature with the
hydrocarbon oils. The separation temperatures
employed are, in general, about 45° F. below the
25 miscibility temperature of the oil and solvent.
the liquids are-only partially miscible, and thereby
effect solution of the naphthenic portion of the
oil in the solvent mixture. . In either of the above
procedures I may take advantage of the prin
ciples of countercurrent extraction.
After the extraction proper, I effect 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,
By employing a suitable mixture of a selective
solvent and an organic acid anhydride, I am able
to separate hydrocarbon oils into fractions at
temperatures considerably above those which
the portion of the solvent mixture which each .
30 could be employed with the selective solvent alone.
For example, 100 parts by volume, of a medium
viscosity lubricating oil distillate from Winkler
(W. Texas) crude oil was mixed with 200 parts,
contains, by suitable procedure, such as by vac
uum distillation, thereby to obtain two oils of simi
lar distillation ranges but of different chemical
by volume, of nitrobenzene, and the miscibility
composition and different physical characteristics.
35 temperature was found to be 79° F. In general,
this would indicate that the extraction should be
Before removing the solvent mixture from the _
undissolved or more paramnic layer, I may add a
further quantity of the solvent mixture and re
peat the extraction, thereby to remove additional
carried out at temperatures not higher than about
35° F.
When 109 parts of the same oil were ad
naphthenic constituents from said layer.
mixed with 200 parts of a solvent composed of
of maleic anhydride, the miscibility temperature
was found to be 104° F., indicating that an ex
traction could be carried out satisfactorily at a
temperature of the order of 60° F. When 100
45 parts, by volume, of the same oil were mixed with
cosity-gravity constant.
A countercurrent relationship in these succes
sive extractions may be established in the conven
tional manner by employing the partially spent
solvent mixture containing dissolved naphthenic
200 parts, by volume, of solvent composed of
90% by volume of nitrobenzene and 10% by
volume of maleic anhydride, the miscibility tem
oil from the succeeding stages of the extraction
system to extract additional quantities of oil in
the preceding stages. In the event that the
miscibility temperature of the oil with the se
lective solvent in the latter stages of the system
perature was found to be 129° R, which would
50 permit of extraction at temperatures as high as
about 85° F. It will be understood, of course,
that the quality of the undissolved or more par
is sufficiently high, the organic acid anhydride
a?inic oil fraction produced by means of the
solvent mixture will frequently be somewhat lower
than that of a similar fraction produced with
nitrobenzene alone. In general, greater yields
are obtained and higher operating temperatures
may be introduced at any desired preceding stage,
in order to lessen or eliminate the refrigeration
required in the earlier stages.
Where substantial quantities of waxy hydro
carbons belonging to the true para?in series
may be employed when a mixture of a selective
(CnH2n+2) are present, such hydrocarbons re
main in the undissolved or more para?inic layer 60
and may cause such layer to be solid or semi
solid, after the removal of the solvent mixture
therefrom. In some cases, the extraction and
separation of the layers may be effected at tem
solvent and an organic acid anhydride is utilized.
60 In any event, an economic balance must be
struck between the yield and quality of the re
?ned oil, and the cost of producing the same.
Furthermore, in accordance with my invention,
I am able to separate hydrocarbon oils into frac
65 tions with my solvent mixture, which oils could
not be economically treated with a selective
solvent alone. For example, it is not practical to
employ a solvent, such as nitrobenzene, in treat
ing very asphaltic oil stocks such as those derived
70 from some California crude oils, for the reason
that the miscibility temperature of the oil and
solvent is very low, excessive refrigeration is re
quired, and in certain cases the nitrobenzene may
crystallize before separation of fractions can be
effected. However, by adding to the selective
The
extraction step may be repeated any desired num 40
ber of times, each repetition producing an oil of
higher para?inicity as evidenced by its lower vis
40 95% by volume of nitrobenzene and 5% by volume
pertures above the melting point of the waxy
hydrocarbons, so that substantial entrainment
of oil in the molten or liquid wax is avoided.
Such layer may be separated into solid and liquid
hydrocarbons by any of the well-known dewax
ing processes, such as by cold-settling, ?ltering,
70
or by centrifuging. In many instances, it may
be advantageous to dewax the oil prior to ex
traction. However, it is ‘to be understood that
in accordance with my invention, dewaxing may
be effected either prior or subsequent to extrac
.
tion.
2,115,704
My invention will be further understood from
the following speci?c examples:
I. 100 parts by volume of‘ a residuum from at
Gulf Coast crude oil having a viscosity of 518
,1 seconds Saybolt universal at 210° F., a speci?c
gravity of 0.9759 at 60° FL, and a viscosity-gravity
constant of 0.894 were mixed with 200 parts by
volume of a solvent consisting of 90% by volume
of nitrobenzene and 10% by volume of acetic
105 anhydride, and heated to slightly above the tem
perature of complete miscibility, i. e., about 115°
F. The homogeneous liquid which resulted was
cooled, with agitation, to about 68° F,, and al
lowed to settle, whereupon a two-layer“ system
16 was formed. After separation, the layers were
each freed of solvent by vacuum distillation. The
resulting undissolved oil fraction comprising
40.3% of the stock had a viscosity of 221 seconds
Saybolt universal at 210° F., a speci?c gravity
20 of 0.9212, and a viscosity-gravity constant of
0.836. The initial Gulf Coast residuum had a
miscibility temperature of 91° F., with nitroben
zene alone, and would have required extraction
at temperatures below 46° F., to effect a satis
25 factory separation of oil fractions.
II. 100 parts by volume of a Barber’s Hill lubri
cating oil distillate having a viscosity of 110 sec
onds Saybolt universal at 210° F., a speci?c grav
ity of 0.926 at 60° F., and a viscosity-gravity con
30 stant of 0.854, were mixed with 200 parts by vol
ume of a solvent consisting of 90% by weight
of nitrobenzene and 10% by weight of phthalic
anhydride, and heated to slightly above the tem
perature of complete miscibility, i. e., about 144°
35 F.
The homogeneous liquid which resulted was
cooled, with agitation, to about 95° F., and al
lowed to settle, whereupon a two-layer system
formed. After separation, the layers were each
freed of solvent by vacuum distillation.
The re
sulting undissolved fraction comprising 56.0%
of the stock had a viscosity of 91 seconds Say
bolt universal at 210° F., a speci?c gravity of
0.9013, and a viscosity-gravity constant of 0.825.
The initial lubricating oil distillate had a mis
cibility temperature of 110° F., with nitrobenzene
alone, and would have required extraction at
temperatures below 65° F., to effect a satisfactory
separation of oil fractions.
3,
re?ned oil fraction had a viscosity of 84 seconds
Saybolt universal at 210° F., a speci?c gravity
of 0.8911, and a viscosity-gravity constant of
0.813. The initial lubricating oil stock had a‘
miscibility temperature of 110° F., with nitro
benzene alone, and would have required extrac
tion at temperatures below 65° F., to effect a
satisfactory separation of the oil into fractions.
From the above examples it will be noted that
by extraction of an oil with a solvent mixture 10
comprising a selective solvent, such as nitroben
zene, and an organic acid anhydride, there may
be obtained‘oil fractions which are respectively
more paraifinic and more naphthenic than the
original oil. By repetition of the extraction proc
ess upon the undissolved fraction, oils of even
greater paraffinicity will result. The quantity of 1
organic acid anhydride to be employed in con
junction with the selective solvent will vary,
depending upon the character of the selective
solvent, the temperature at which the extraction
is to be carried out, and the quality of re?ned
oil desired. In general, the quantity of organic
acid anhydride employed will be of the order
of from about 5% to about 10% of the selective 25
solvent.
However, more or less of the organic
acid anhydride may be employed, depending upon
the temperature at which the extraction is to
be carried out.
While, in the above examples, I have shown 30
the use of a selective solvent such as nitrobenzene
in admixture with various organic acid anhy
drides, I do not intend to limit myself thereto,
but may employ various selective solvents in con
junction with the organic acid anhydrides. The 35
following table illustrates the effect upon the mis
cibility temperature of oil with various selective
solvents to which have been added small quan
tities of an organic acid anhydride. The mis
cibility temperatures were determined by heating 40
1 volume of lubricating oil stock with 2 volumes
of selective solvent or solvent mixture, to a tem~
perature such that complete solution of oil and
solvent was obtained, and thereafter cooling the 45
solution until the formation of a haze was noted,
thus indicating the separation of two liquid
phases.
Selective solvent, percent by Acid anhydride, percent by
volume
volume
Misci-
‘38511133’
mm
increase
°F.
55
77
60
90
Bcnzaldehyde ___________ __
D0 __________________ ~_
“B, 8
°F.
110
174
0 __________________ __
M-i-Sci'
bility
tempera
________ _ ..
64
________ _ _
147
70
100
103
........ ._
90
165
62
BB’ diChlOl'O ethyl ether“ 100
143
________ __
D __________________ __
197
54
293
________ _.
313
25
163
225
________ _.
62
90
Furt'ural - __
DO ________ _ ..
Cresylic acid. .
Do __________________ _ .
III. The same Barber’s Hill lubricating oil dis
tillate as shown in Example II was continuously
extracted in a 3—stage countercurrent system with
200% by volume of a solvent comprising 90%
by volume of nitrobenzene and 10% by volume
of maleic anhydride, at a temperature of about
131° F., or about 43°
below the temperature
of miscibility, i. e., 174° F. The resulting undis
solved oil fraction, after removal of solvent by
vacuum distillation, comprised 45.2% of the oil
75 stock charged to the extraction system. This
Maleic anhydride ..... ._ 10
(i i)
My process is practically independent of the
particular nature or source of the crude oil or oil
fraction to be extracted. There may be produced
by my process oil products of desired character
istics from oil which by distillation will not pro
duce such products. Moreover, it will be under 70
stood, that in accordance with my invention, an
important aspect thereof is the increase of the
miscibility temperature of the oil and naphthenic
solvent by reason of the presence of the organic
acid anhydride, regardless of any selective sol
75
4
2,115,704
vent action the anhydride itself may have upon
the oil.
When, in the appended claims, oil is referred
to as being “viscous”, it is to be understood that
1 the oil is of substantial viscosity, i. e., of the
order of 50 seconds Sayboit universal at 100° F.,
or more.
What I claim is:
1. In the process of decreasing the viscosity
gravity constant of a viscous mineral oil, the step
substantially increase the miscibility temperature
of said nitrobenzene with said oil.
3. In the process of decreasing the viscosity
gravity constant of a viscous mineral oil, the step
of extracting the oil with nitrobenzene containing
acetic anhydride in suf?cient quantity to substan
tially increase the miscibility temperature of said
nitrobenzene with said oil.
4. In the process of decreasing the viscosity
gravity constant of a viscous mineral oil, the step 10’
of extracting the oil with nitrobenzene containing
of extracting the oil with nitrobenzene contain
maleic anhydride in suf?cient quantity to sub
ing an organic acid anhydride from the group
stantially increase the miscibility temperature of
consisting of acetic anhydride, maleic anhydride,
and phthalic anhydride, said anhydride being
said nitrobenzene with said oil.
2. In the process of decreasing the viscosity
gravity constant of a'viscous mineral oil, the step
of extracting the oil with nitrobenzene contain
ing phthalio anhydride in sui?cient quantity to
present in suf?cient quantity to substantially in— 151
crease the miscibility temperature of said nitro
benzene with said oil.
EUGENE R. BROWNSCOMBE.
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