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sept. l1o, -1946.v`
c. R. CLARK
2,407,364
PROCESS FOR THE RECOVERY OF TOLUENE FROM OILS
Filed July 1o, 1945
1
ATTORNEY
2,407,364
Patented Sept. 10, 1946.
UNITED STATES, PATENT OFFICE
PROCESS FOR THE REoovERyr OF TOLUENE
»
FROM OILS
Charles R. Clark, New York, N. Y., assignor to `
Allied Chemical & Dye Corporation, New York,
N. Y., a corporation of New York
Application July.10, 1945, Serial N0. 604,130
Vfron'ims. (ol. 2oz-_42)
'
This invention relates to a process for recover
ing toluene from mixtures containing it Aand
other organic liquids.
This application is a continuation-impart of
my co-pending application Serial No. 343,499,
iiled July 1,1940.
2
1
`
Numerous hydrocarbon oils are known which
contain toluene in varying proportions. For eX
arnple, catalytic treatment of a suitable petro
leum fraction in the presence of hydrogen, gives
an oil consisting chiefly of hydrocarbons of both
aromatic and non-aromatic character, and con
taining about 20% toluene. Gasoline fractions
obtained by the distillation of certain types of
petroleum frequently contain substantial propor
tions of` toluene, although mainly consisting of
other hydrocarbons. Oils of petroleum origin
fraction containing about 82% to 35% toluene
appears to represent a product of maximum tolu
ene concentration obtainable by direct fractional
distillation. Accordingly, recovery of toluene of
a relatively high purity from these sources pre
sents a diii‘lcultV problem of great industrial im-Y
portance.A
_
>
»
‘ For many purposes to which toluene is put, it is
desirable to use as pure a material as _may be
economically available. For example, toluene is
largely used for the production of TNT, for which
purpose a so-called “nitration grade” of toluene
is now preferred.
While toluene products con
taining substantial proportions of certain hydro
carbon oils other than toluene can be nitrated,
the mono-nitro compound vmade from them must
be purified prior to complete nitration. This ma
terially increases the cost and complexity of the
having a considerable content of aromatics, in
process for making TNT. Furthermore, even
cluding toluene, may be treated by well known
selective-solvent processes to produce fractions 20 though toluene containing substantial quantities
of certain other materials is sometimes used for
rich in aroma-tics;A for example, extraction of
nitration, this is only because the difficulties of
suitable fractions of such petroleum oils with
preparing a pure toluene have outweighed the
sulfur dioxide may yield fractions of high toluene
disadvantages of using the impure toluene for
content. In such cases toluene is accompanied
by non-aromatic oils which may be largely par- v 25 the production of explosives. Direct fractional
distillation, because of the difliculties pointed out
aliinic, naphthenic or olefinic in character. A
above, Will not eiT'ect a recovery of pure toluene
considerable portion of these oils cannot be comN
pletely separated from the toluene by direct-fram
from oils such as enumerated and in many cases
will not give fractions of suitably high toluene
tional distillation because of the closeness of
their boiling points to that of toluene or because 30 content or free from materials which even in
small concentrations adversely affect the nitra
.they form constant boiling mixtures with toluene.
tion of the toluene or the nitrated product.
Furthermore, while ordinarily toluenevis readily
It is an object of my invention to provide a
separable by direct fractional distillation from
process whereby toluene of any desired degree of
light oils produced by the gasification of coal, in
some cases the toluene is accompanied by diñl 35 purity may be recovered from Oils containing it
and other hydrocarbons which distill out over the
cultly separable non-aromatic oils of the same
same temperature range as >the toluene, which
general character as described, owing to car
will be referred to as “like-boiling, non-aromatic
bonization conditions, type of coal used or other
hydrocarbons.”
special circumstances. Also synthetic hydrocar
bon gas mixtures produced by various catalytic 40 I have now. discovered a relatively pure tolu
ene, accompanied by no more" than 5% of like
boiling, non-aromatic hydrocarbons, can be re
covered from many -oils containing toluene and
arable constituents.
~
,
other hydrocarbons by an azeotropic distillation
ABy fractional distillation of these oils contain
ing toluene, fractions relatively high in toluene` 45 of the oil under the conditions hereinafter de
scribed. '
content may be obtained. These toluene frac
processes may contain toluene which, when re->
covered, is accompanied by similar ldirliculty sep
tions, however, will still contain large amounts
In using my invention for the treatment of an
Oil such as has been described above, containing
of the other constituents. of the oil having boil»
toluene and other hydrocarbons, particularly
ing points in the neighborhood of the boiling
point of toluene or forming mixtures of constant 50> when the toluene concentration of the oil is low
boiling points in the range 0f temperatures at '
which toluene distills from the oil. For example,
by distillation of the above-described types of oils
or the oil is one containing materials of wide
boiling range, I prefer first to non-azeotropically
fractionally distill the oil (i. e., to fractionally
distill the oil in the absence of added azeotropic
ditions practicable for rectifying the vapors, a 55 agent) to recover therefromv an enriched tolu»
containing toluene under the most eilìcient con
2,407,364
3
4
ene fraction which contains, in addition to tolu
ene, other hydrocarbons Which distill at the same
temperatures as the toluene. Although toluene
fractions having an end boiling point substan
tially above the boiling point of toluene (e. g. a
in the still and/ or rectification column during the
distillation of the toluene fraction to selectively
carry over through the rectiñcation treatment the
vapors of the hydrocarbons to be removed from
the toluene. Some of the toluene may also bc
boiling point Urp to 113° C.) may be azeotropically
distilled in the manner hereinafter described, I
>carried over., ybut so long as the above tempera
tures are not exceeded, the undistilled residue
will be enriched in toluene and by continuing the
distillation, separation of the toluene from the
hydrocarbons of similar boiling range will be ac
prefer the toluene fraction recovered in the pre
liminary non-azeotropic distillation step by one
having a maximum boiling point substantially
corresponding to the boiling point Vof pure tolu
complished.
After the distillation has been carried to the
ene; i. e., 111° C. Further, for the reasons which
point at which the residue containing toluene has
the desired purity with respect to hydrocarbons
will be more specifically pointed out below, 1I pre
fer that the toluene fraction recovered by the
preliminary distillation of the crude toluene oil
distilling Vfrom the toluene fraction in the same
temperature range as the toluene distille there
be so cut as to exclude therefrom the forerun
from in the absence of the azeotropic agent, the
distillation may be stopped and the residue With
drawn from the still. Usually the toluene frac
tion subjected to azeotropic distillation in prac
nìngs which do not contain substantial propor
tions of toluene, for example to exclude any ma
terials distilling beloW 100° C.
A toluene fraction such as may be obtained by
ticing this invention will be one having a top
this preliminary distillation, which may contain
parafñns, naphthenes, or oleñns, is subjected -to
boiling point not above 118° C. and preferably not
above 111° C. The toluene fraction, therefore,
will contain little, if any, hydrocarbons boiling
from the fraction at `temperatures above those at
which toluene boils therefrom. Accordingly, the
residue Withdrawn from the still `ordinarily Will
contain toluene and other hydrocarbons in the
a second distillation in the presence of the
methyl, ethyl or butyl ether of ethylene glycol.
TheseV materials act as azeotropic agents during
the distillation. I have discovered that when one
of these materials is mixed With a toluene frac
tion such as described above and the mixture is
proportion of 95 or more parts toluene to 5 or
tion of the vapors under conditi-ons such vthat a 30 less parts of total hydrocarbons other than
toluene. It may be puriñed further, as desired, to
temperature not exceeding a Well deñned maxi
remove any azeotropic agent it contains and to
mum is maintained at a point in the rectiñcation
subjected to fractional distillation with rectifica
remove any other impurities present. When the
of the vapors, non-toluene hydrocarbons present
distillation is carried to the point at Which all of
in the toluene fraction are distilled from the mix
ture in the form of their azeotropes with the 35 the azeotropic agent has been distilled out of the
residue and lthe toluene constitutes substantially
99% or more of the »total hydrocarbon content of
the residue, the residue, which may be given a
azeotropic agen-t to leave a residue containing
toluene of a desirable high purity with respect to
its content of other hydrocarbons originally pres
ent in the toluene fraction and not separable
from the toluene by direct fractional distillation
of the toluene fraction in the absence of the
conventional treatment, for example, treatment
With sulfuric acid and redistillation, is suitable
for marketing as a nitration grade toluene of
particularly high purity.
azeotropic agent.
My invention comprises azeotropically distilling
’Instead of withdrawing the toluene residue
from the still, the distillation may be continued
a toluene fraction containing hydrocarbons which
have similar boiling points to that of the »toluene` 45 and the toluene distilled over and separately col
lected from the distillate containing the hydro
With rectification of the evolved vapors in the
carbons from which the toluene residue previously
presence of the azeotropic Vagent While maintain
has been separated by azeotropic distillation. If
ing at a point in the rectification of the vapors a
azeotropic agent is present during the distillation
temperature not -above the boiling point of the
azeotrope Vof toluene and the azeotropic agent 50 and collection of the toluene, the azeotrope of
toluene may be distilled out. The toluene may be
(hereinafter referred to as the “control tempera
separated in any suitable manner from the
ture”), until the unvaporized residue contains at
toluene
azeotrope recovered by distillation, for
least 95 parts by weight toluene for every 5 parts
example by extraction with a liquid which will
by weight of said hydrocarbons, which boil from
a mixture consisting of toluene and the hydro 55 form separate layers, one containing the toluene
and the other containing the azeotropic agent.
carbons in the same temperature range as the
Water is a suitable liquid for effecting this sepa
toluene boils therefrom. This control tempera
ration. In the absence of azeotropic agent, in
ture will depend upon the azeotropic agent used<
distilling out the toluene the temperature in the
The following Vtable gives for each material the
rectification
column may rise to the boiling point
control temperature» at or below which the vapors
'of toluene under the conditions prevailing as to
should be maintained at some point in their
pressure, etc.
rectification when using a given material for the
As stated above, ordinarily the toluene fraction
distillation of a toluene fraction:
.
U
Azeotropic agent
.
-
Control tem
treated in accordance With my invention will con
65 tain` little, if any, hydrocarbons distilling from the
hydrocarbon-toluene fraction at temperatures
perature
D
above those at which toluene distills therefrom.
On the other hand, it is not necessary that such
C’.
Mono-methyl ether of ethylene glycol ______________ ._
Mono-ethvl other of ethylene glycol ________________ ._
106
110
Mono-butyl ether of ethylene glycol _______________ . ,
110
high boiling hydrocarbons always be excluded
70 from the mixture of aaeotropic agent and toluene
fraction subjected to» distillation in accordance
with my invention. For example, one may desire
to azeotropically distill a toluene oil from which
Regulation of the temperature in the rectiñca
tion of the vapors to meet the conditions set
forth above is accomplished by maintaining an
adequate quantity of the azeotropic agent present
l75
all high boiling hydrocarbons have not been re
moved. In that case, the high boiling hydrocar
2,407,364
.
.
5
drawn therefrom. The cut in vessel 9 contains the
bons may be left with the toluene residue at the
conclusion of the azeotropic distillation of the
low boiling fraction of the original oil. The resi
due Withdrawn from the still contains the high
boiling components of that oil. This fraction and
residue may be treated or yused in any desired
toluene fraction under the conditions set forth .
above to separate the toluene from the hydrocar
bons of similar boiling range. After this separa
tion has been effected, one may then separate the
manner.
in the residue by fractional distillation in the ab
sence of the azeotropic agent.
My invention will be more particularly illus
trated and described vin conjunction with the fol
.
Instead of discontinuing the distillation after
the desired cutis taken off to vessel I0, the distil
toluene from» high Aboiling hydrocarbons present
lation may be continued and the condensate pass
10 ing forward through pipe 8 collected in a third
vessel, not shown in the drawing, While the distil
lation is continued as long as may be desired. The
cuts in vessel 9 and this third vessel contain low
lowing example.
The accompanying drawing diagrammatically
and high boiling fractions of the original oil. If
the processes of this example.
15 the cut taken ofi” to the third vessel is limited to
one containing substantial proportions of toluene, f
The apparatus of the drawing comprises a still
e. g. up to 115° C. or 120° C., this cut may be redis-`
I provided witha heater 2 and ‘connected with a
illustrates an apparatus suitable for carrying out Y
rectification column 3' and a condenser 4 for the
vapors leaving the top of the- column. By means
Vof valves 5 and 6, condensate flowing from con
denser 4 is returned through pipe 'I to the top of
column 3 and refluxed in contact with the vapors
rising in the column. The other portion of the
condensate is withdrawn through pipe 8. Two
receivers 9 and Ill are connected to pipe 8 through
valve-controlled branch pipes: II and I2 so that
the condensate drawn off through pipe B may be
divided and distributed as described below to the
vtwo receivers.
Receiver IQ is connected by a pipe I3 controlled
by valve I4 with a second still I5. Still I5, like
still I, is provided with a heaterk I 6, a rectification
column I‘I, a condenser I8 and pipes I9 and 29
controlled by valves 2| and 22 for return of de
termined proportions o-f condensate from con
denser I8 to the top of column I'I and withdrawal
of another portion of the condensate through pipe
20. Pipe 2D leads to a separator 23 into which
water may be introduced from a pipe 24.
In carrying out one embodiment of my inven
tilled o-r introduced to still I with a subsequent
~ batch of oil, and the toluene in this cut recovered.
20
With efñcient rectification of the vapors in col
umn 3 during the fractional 'distillation of the
crude toluene oiljthe cut collected in vessel I0
contains about '74% by Weight of toluene, as de
termined by the specific dispersion method for
25 analyzing hydrocarbon oils described in Industrial
and Engineering Chemistry, Analytical Edition,
vol. l1, page 614, November 15, 1939.
The toluene fraction collected in vessel Iß is
subjected to azeotropic distillation, which repre
30 sents the second stage of this example. For this
purpose the toluene fraction containing '74% tolu
ene was introduced into still I5 together with
commercial methyl ether of ethylene glycol. The
mixture o-f-methyl ether of ethylene glycol and
35 toluene fraction Was distilled with rectiiication
of the vapors in column I‘I and condensation of
the vapors: leaving the top of the column in con
denser I`8. Most of the condensate was returned
through pipe I9 to the top of column I‘I while the
40 remainder was withdrawn through pipe 20 to sep
tion in the apparatus described above, a liquid
arator 23.
n
,
hydrocarbon mixture containing about 20% tol«
Toluene and the methyl ether of ethylene gly
uene, 20% of other aromatic hydrocarbons and
the remainder substantially consisting of paraf
iinic and naphthenic hydrocarbons, with only
traces of oleñns, was introduced into still I. This
crude toluene material was produced by catalytic
treatment of a petroleum distillate in the presence
col form an azeotrope having a boiling point of
106° C. Azeotropes formed with the methyl ether
of hydrogen.
f
The charge of this hydrocarbon mixture intro- f
`duced into still I was boiled in the still and the
evolved vapors were counter-currently contacted
in column 3 with reñux from condenser 4, in
which the vapors leaving the top of the column
were substantially entirely condensed.
'
of ethylene glycol by the hydrocarbons other
than toluene present in the toluene 'fraction in
troduced into still I5 have boiling points suffi
ciently below that of the toluene azeotrope for
them to be preferentially vaporized and by recti
fication in column I1 to be largely separated from
the toluene and- any toluene-methyl ether of
ethylene glycol azeotrope which is vaporized in
still I5 and enters column I1 so long as there-is
suflicient methyl ether of ethylene glycol pres
Most 01"-,y f ent in the vapor and liquid phases in the recti
fication column. _ As pointed out above, the req
the condensate from condenser 4 was returned
through valve 5 and pipe ‘I to the top of the col
umn to furnish the reflux for the column, the re
uisite quantity of methyl ether of ethylene glycol
to be supplied is that which will maintain the
maining small portion of the condensate being
temperature at apoint in the rectification col
continuously withdrawn through valve G and pipe Gi) umn, preferably at the top of the column, not
8 and passed into collecting vessel 9. The distilla
above 106° C. In this example the requisite
tion was conducted under substantially atmos
quantity of methyl ether of ethylene glycol is
pheric pressure; i. e., the pressure in condenser d
vsupplied in the initial fcharge to the still by in
and at the top of column 3 was substantially at
troducing about 30 volumes of the methyl ether
mospheric and the pressure in still I was only.
of ethylene glycol for every 100 volumes of the
enough higher to force the vapor through the rec
toluene fraction.. Methyl ether of ethylene gly
tiñcation column to the condenser.
col is vaporized from the still, enters the recti
When the vapor temperature in the top of colñcation column as vapor and in part is returned
umn 3 reached 109.’7° C., the condensate passing
to the column as liquid in the condensate from
through pipe 8 was diverted to vessel I0. The cut ~ condenser I8. If insuiñcient methyl ether of eth
taken in vessel I0 included the distillaœ coming
ylene glycol is initially introduced in the charge
over up to and at a temperature of 110.8° C. at
to the still, additional methyl ether of ethylene
the top` of the column. After this out has ~been
glycol, sufficient to maintain the requisite tem
taken off to vessel I D, the distillation may be dis
perature in the rectification column, may be sup
continued and the residue left in the still with- '
plied as the distillation progresses. , This methyl
7
ether of ethylene glycol may be introduced either
into the still or into the rectification column it
self. The toluene is in large part returned down
the rectilication column and retained in the still,
5
the azeotropic agent a toluene fraction boiling,
for example, from 95° C. to 118° C., but the quan
tity of azeotropic agent present in the distilla
tion of the toluene fraction of wider boiling range
while the azeotropes of the methyl ether of ethyl- .i
must be substantially increased as compared with
ene glycol with the other hydrocarbons are dis
the quantity which sufñces for distilling the frac
tion of the narrower boiling range.
tilled out and are collected in separator 23. The
loss of toluene from the still to the condensate
While I have described my process in conjunc
ion with an example in which the two distillation
steps are batch procedures, either or both of
efficiency with which the vapors are rectiñed.
these distillations advantageously may be carried
Efficient rectiñcation is employed in order to keep
out continuously by well known continuous dis
down this loss of toluene.
tillation procedures suitable for the fractional
in carrying out the process of this example,
distillation of mixtures of two or more liquids.
as the distillation continued the temperature of
The minimum ratio of azeotropic agent to the
the vapors at the top of column l'l rose to about
toluene fraction which is suitable for carrying out
106C’ C. The toluene content of the oil obtained
my invention will vary with the particular agent
from the condensate withdrawn through pipe 2l)
used, the amount and nature of the hydrocarbon
by Washing the condensate with water to free it
impurities in the toluene fraction, the purity de
of methyl ether of ethylene glycol increased to
sired in the toluene residue _from the distillation,
about 99 %. At this point the distillation was
the proportion oi’ toluene in the original toluene
discontinued. The residue left in still I5 may
fraction which is to be recovered in the residue
be Washed with water to remove methyl ether
from the distillation, and theprocedure used for
of ethylene glycol. The oil layer which separates
the azeotropic distillation. The ratios of the
from a water-methyl ether of ethylene glycol
25 above examples are suitable for a batch process
layer contains about 99% toluene.
carried out according to the procedures of the
By agitating the distillate collected in separa
example. irrespective of the particular batch or
tor 23 with Water and allowing the liquid to re
continuous procedure used, the quantity of azeo
main quiescent for a short time, it will separate
tropic agent used in the distillation of hydro
into» two layers. The upper layer is an oil con
taining the non-toluene constituents of the tol- u carbons from a given quantity of toluene frac
tion should be in excess of that which will form
nene fraction originally supplied to still I5 and
azeotropic mixtures with the non-toluene hydro
the portion of the toluene carried over in the
carbons which are to be vaporized and taken over
distillation. 'This oil may be treated or used as
into the distillate. This quantity of azeotropic
desired. By separately recovering and treating
agent includes fresh agent introduced into the
the distillate in two portions, two oil fractions
material being distilled and also any of the azeo
may be obtained; one low in toluene, which may
tropic agent which may be separated from the
be added to toluene oil distilled in still I, and
distillate and. returned continuously or periodi
a second oil fraction high in toluene, for exam
cally to the still or rectiiication column while the
ple containing 74% toluene, which may be in
troduced into the toluene fraction from vessel I0 40 distillation of the toluene fraction is progressing.
rlleinperature readings are taken of the vapor at
and redistilled with this fraction in a subsequent
the top of the rectification column and, by sup
distillation in still i5. By thus reworking the dis- .
plying additional azeotropic agent when required
tillate the toluene it contains may be recovered.
to prevent this temperature from rising above the
The aqueous methyl ether of ethylene glycol layer
separated in treating the distillate with Water » boiling point of the toluene azeotrope, an ade
quate amount of azeotropic agent will be present
may be treated in any of the well known man
during the separation of the non-toluene hydro
ners to recover methyl ether of ethylene glycol
carbons from the toluene fraction. It is not
therefrom for use in distilling a subsequent batch
necessary that this point of control temperature
of toluene fraction.
l
be at the top of the column, although this is a
The procedure of this example may be em
drawn off through pipe 20 will depend upon the
ployed to recover 95% or purer toluene from the
starting hydrocarbon mixture using ethyl ether
of ethylene glycol or butyl ether of ethylene gly
col as the azeotropic agent in place of the methyl
ether of ethylene glycol.
Numerous changes and modiñcations may be
made in the above-described processes without
departing from my invention. While in the first
distillation step of the crude toluene oil it is pre
ferred to take off a toluene fraction having an
end boiling point of substantially 111° C. and
fractions with a higher end boiling point, such
satisfactory point for determining this tempera
ture in the equipment used for fractionating the
vapors and condensing the fractionated vapors in
the above examples for effective use of the recti
ñcation column. One skilled in the distillation art
will recognize suitable points for maintaining this
control temperature in any other specinc appara
tus according to well known distillation prin
ciples.
It is, of course, obvious preliminary distillation
of a crude toluene oil to obtain a toluene fraction
suitable for recovery of toluene therefrom by the
azeotrcpic distillation need not be carried out in
immediate conjunction with the azeotropic dis
leeway is permitted in the temperature at which 65 tillation. rlille toluene fraction may be produced
in one plant, transported to and treated later in
the toluene fraction starts to be taken off; i. e.,
another plant to aueotropically distill it. Nor is
in the initial boiling point of the toluene frac
my invention limited to any particular procedure
tion. Nevertheless, it is preferred the toluene
for the production oi’ the toluene fraction. My
fraction subjected to azeotropic distillation be
one boiling in the range of 100° C. to 111° C. 70 invention contemplates distilling with the methyl,
ethyl or butyl ether of ethylene glycol any oil
Such a fraction may be distilled in the azeotropic
containing toluene together with other hydro
distillation step of my process and pure toluene
carbons which, when the oil is distilled, vaporize
obtained with a relatively small quantity of azeo
as 118° C.; may be successfully distilled azeo
tropically to obtain pure toluene, even a larger
therefrom in the same temperature range as the
tropic agent present during the distillation.
Pure toluene may be obtained by distilling with 75 toluene and, therefore, are not separable from the
2,407,364
l0
toluene by direct fractional distillation. As used
in this speciñcation and the appended claims, the
which ordinarily distillV from said hydrocarbon
fraction in the same temperature range as toluene
containing oils, whether produced by fractional
distills therefrom which comprises azeotropically
distilling said hydrocarbon fraction in the
distillation or toluene-containing materials or by
presence of a sufficient amount of a material from
any other means.
the group consisting of the methyl, ethyl and
butyl ethers of ethylene glycol to vaporize the
non-aromatic hydrocarbons together With the
ether of ethylene glycol thereby leaving toluene
term “toluene fraction” refers to all such toluene
In this specification I have described the azeo
tropic distillation of toluene fractions as carried
out under substantially atmospheric pressure. It
is, of course, possible to aaeotropicaliy distill the
toluene fraction under pressures above or below
atmospheric. In that case the particular tem
perature used as a control for the amount of azeo
tropic agent present in the distillation will corre
spond to the change inthe boiling point of the `
toluene azeotrope with change in pressure. The
temperatures as given in this specification and
in the appended claims are corrected tempera
tures for oner atmosphere pressure (760 mm. of
Hg).
I claim:
l
’
-
" in the residue substantially completely separated
from the hydrocarbons other than the toluene.
3. A process for the treatment of a hydrocar
bon fraction containing toluene and non-aromatic
hydrocarbons to separate toluene from the non
aromatic hydrocarbons contained therein Which
ordinarily distill from said hydrocarbon fraction
in the same temperature range as toluene distills
therefrom which comprises azeotropically dis
tilling said hydrocarbon fraction in the presence
of a suñicient amount of methyl ether of ethylene f
glycol to vaporize the non-aromatic hydrocarbons
together With the methyl'ether of ethylene glycol
'
1. A process for the treatment of a hydrocar
bon fraction containing toluene and non-aromatic
thereby leaving a residue substantially enriched
hydrocarbons to separate toluene from the non
in toluene.
aromatic hydrocarbons contained therein which 25
4. A process for the treatment of a hydrocar
ordinarily distill from said hydrocarbon fraction
bon fraction containing toluene and non-aromatic
in the same temperature range as toluene distills
hydrocarbons to separate toluene from the non
aromatio hydrocarbons contained therein which
therefrom which comprises azeotropically distill
ing said hydrocarbon fraction in the presence of a
ordinarily distill from said hydrocarbon fraction
suñicient amount of a material from the group /
in the same temperature range as toluene distills
consisting of the methyl, ethyl and butyl ethers of
ethylene glycol t0 vaporize the non-aromatic
hydrocarbons together with the ether of ethylene
glycol thereby leaving a residue substantially en
therefrom which comprises azeotropically dis
tilling said hydrocarbon fraction in the presence
of a sufficient amount of methyl ether of ethylene
glycol to vaporize the non-aromatic hydrocarbons
together With the methyl ether of ethylene glycol
thereby leaving toluene in the residue substan
riched in toluene.
'
.
2. A process for the treatment of a hydrocar
bon fraction having an end boiling point not
above 118° C. and containing toluene and non
aromatic hydrocarbons to separate toluene from
the non-aromatic hydrocarbons contained therein
tially completely separated from the hydrocar
bons other than the toluene.
CHARLES R. CLARK.
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