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2,403,972
Patented July 16, 1946
UNETED STATES ‘PATENT. OFFICE
2,403,972
PROCESS FOR EXTRACTING AN AROMATIC
HYDROCARBON FROM A MIXTURE CON
TAINING OTHER HYDROCABBONS
Bernar'd S. Friedman, Riverside, Ill., assignor to
Universal Oil Products Company, Chicago, 111.,
a corporation of Delaware
No Drawing. Application May 20, 1948,
Serial No. 487,806 7
15 Claims.
This invention relates to a process for the sepa
ration of hydrocarbons, and particularly aro
matic hydrocarbons, and to a novel separating
agent therefor.
In a broad aspect the
prises the treatment of
with a separating agent
dissolved in sulfuric acid
and sulfonic acids.
(Cl. 260-4574)
2
1
present invention com
a hydrocarbon mixture
comprising a silver salt
or a mixture of sulfuric
In a speci?c embodiment the present invention
comprises the separation of aromatic hydrocar
bons from other constituents of a hydrocarbon
mixture by treatment with silver sulfate dissolved
in sulfuric acid under conditions to form an ex
tract phase and a rat?nate phase.
In another speci?c embodiment the present
invention comprises the separation of aromatic
hydrocarbons from other constituents of a hydro
carbon mixture by treatment with silver sulfate
dissolved in a mixture of sulfuric and sulfonic
acids under conditions to form an extract phase
and a ra?inate phase.
accordance with the present invention to sepa
rate the mono-cyclic from‘ the poly-cyclic aro->
matic‘ hydrocarbons.
"
The present invention is characterized by the
novel separating agent, which broadly comprises’
a solution of a silver salt in sulfuric ‘acid or a
mixture of sulfuric and sulfonic acids and par-V
ticularly a’ solution of'silver sulfate in sulfuric
acid or a mixture of sulfuric and aromatic'sul
fonic acids. I have discovered that the separat
ing‘ agent of the present invention is especially
eifective in'accomplishing the separation of aro
matic hydrocarbons. The separating agent vhere
in disclosed has a ‘high capacity; that is‘, it will
dissolve large proportions of the desired'com
pounds; and, in addition, it has a high selectivity;
that is, it will dissolve the aromatic hydrocarbons
preferentially to the non-aromatic hydrocarbons.
The-separating agent of "the present invention
20 preferably comprises silver sulfate dissolved .in
sulfuric acid orya mixture of sulfuric and sul-,
ionic acids. Any/suitable salt of silver may be
used, e. g.,! silver sulfate andrcarbonate, but not
The present invention is directed primarily to
necessarily with the equivalent results. The-oxide
the separation of aromatic hydrocarbons from a
hydrocarbon mixture containing the same and 25 of silver may also be employed in some instances.
My experiments have indicated that best' re
other constituents by means of the preferential
sults are'obtained when employing a high con’.
solubility of the aromatic hydrocarbons in the
centration of the silver salt. However, the con
separating agent of the present invention. Thus
centration of the silver salt which may be utilized
the present invention may be utilized for the
separation of aromatic hydrocarbons from a mix-. 30 in the separating agent is limited by theconcen»
tration of the sulfuric acid.‘ ' The concentration
ture containing the same and para?inic and/or
of sulfuric acid usually will range ‘from 65% to
naphthenic hydrocarbons. Likewise, the inven
100% or even more but preferably‘isfrom 75%
tion may be employed, for example, for the
to 100%.
~
2
»
i
puri?cation of a substantially saturated hydro
The separating agent of the present invention
carbon fraction such as straight run gasolines
which usually contains a small proportion of aro
matic hydrocarbons, the aromatic hydrocarbons
being removed from hydrocarbon fractions by
means of the present invention, to leave a sub
may readily be prepared by-adding a'suitable'
silver salt to sulfuric acid of the desired concen-..
tration in order to obtain a ?nal mixturehaving '
the vrequiredcomposition. Ingeneral, the con‘
stantially saturated hydrocarbon fraction which 1.10 centration‘ of the acid should be between‘ about.
757170 about 96% or more and the amount of silver‘
will contain substantially no aromatic hydrocar
salt added may range from about 1 part by weight. a
bons or at least less aromatic hydrocarbons than
to a saturated or1 even supersaturated solution.
were present in the original hydrocarbon frac
A suitable separating agent, for example, has been
tion. It is preferred that the hydrocarbon frac
tion treated in accordance with the present in
vention contains substantially no ole?nic hydro
carbons or that if there are olefins in the mix
ture, they should constitute less than say about
10% and preferably less than 5% of the mixture.
In certain cases the present invention may be
utilized for the treatment of a hydrocarbon frac
tion containing only aromatic hydrocarbons, these
being of different types. For example, a, hydro
carbon fraction containing mono-cyclic and poly
cyclic aromatic hydrocarbons may be treated in
. . prepared by admixing 10 parts by weight of silver
sulfate with 90 parts by weight of 96% sulfuric
acid.
7
“
"
A separating agentwhich has been prepared ,
as heretofore described will, when contacted
with ahydrocarbon mixture containing aromatic
hydrocarbons, react with the aromatic hydro
carbons to form aromatic sulfonic acids. I have
found that'the silver salt dissolved ina mixture
of sulfuric and sulfonic‘ acids is an effective sep
arating ‘agent for aromatic hydrocarbons.
2,403,972
3
4
As will hereinafter be described in detail, the
sulfonic acid enhances the solubility of silver
sulfate in the acid and thus permits dissolving
a greater amount of silver salt on the separating
agent. Therefore, it is desired to use a com-i
the sulfonic acid of toluene, mesitylene, amyl
naphthalene and diamyl-naphthalene under at
mospheric conditions, the silver sulfate-sulfuric
acid mixtures solidify and thus are unsatisfactory
for use at atmospheric conditions.
In certain cases the separating agent may com
prise a mixture of a silver salt dissolved in a
sulfonic acid without any appreciable amounts
of sulfuric acid being present. However, in cer
paratively high concentration of sulfuric acid not
only because it dissolves large quantities of the
silver salt, but also because the more highly, i
concentrated sulfuric acid will react with the
aromatic hydrocarbons to produce more aromatic 10 tain tests which I have conducted I have found
sulfonic acids.
'
.
.
that silver sulfate .is: only slightly soluble in ben
It is a particular feature of the present in
zene sulfonic acid and, therefore, in general such
vention that the separating agent may be pre
a mixture is not preferred. It is understood
pared by admixing the silver salt with sulfuric
nevertheless that there may be operations in
acid and subsequently, either as a separate step 15 which such a dilute solution is satisfactory and
or during the initial period of the separating
thus solutions of silver salt in sulfonic acid are
process, reacting the mixture of silver saltand
included within the broad scope of the present
sulfuric acid with aromatic hydrocarbons in
invention but not on an equivalent basis with
order to produce the sulfonic acid. Incommer
the mixtures containing sulfuric acid.
cial operations it probably will .be preferred to 2O
The temperature employed in the separation
prepare the desired mixture of silver salt and
process will depend upon the particular com
sulfuric acid and thenxcontact the mixture with
pounds being treated and upon the particular
the hydrocarbon fraction which it is desired to
separating agent being employed and may range
treat in the process, thus forming the sulfonic
from subatmospheric up to 150° F., or more, and
during the initial period of the separating 25 preferably of from about 50,110 about 100° F. Al
process.
though atmospheric, subatmospheric or super
Asanother feature of the present invention, it
atmospheric pressures may ‘be employed, it is
has been found that the sulfonic acid increases
generally preferred to employ su?icient super
thesolubility of the silver salt in the acid. For
atmospheric pressure in order, to maintain the
example, a separating agent comprising 100 parts
hydrocarbons in substantially liquid phase.
byweight of sulfuric acid of 65% concentration
Any suitable type of apparatus may be em
dissolved only 2 parts by Weight of silver sulfate
ployed for effecting the-desired separation, and
to form a saturated solution. On the other
this may take the form of a single or multiple
hand, 100 parts by weight of sulfuric acid of
stage operation._ Batch operations may be ef
65% concentration admixed with 186 parts by 35 fected by contactingthe hydrocarbon mixture
weight of benzene sulfonic acid dissolved 25 parts
and the separating, agent in a vessel which is
by Weight of silver sulfate.‘ However, it has
maintained at the proper temperature and pres
been_found that, even though such a mixture
sure conditions and which preferably is provided
of silver salt, sulfuric acid, sulfonic acid, and
with some sort of stirring mechanism. After
water, has been prepared, the mixturemay still
satisfactory mixing has been accomplished, the
react ‘to sulfonate additional aromatic hydro
mixture may be allowed tosettle into an extract
carbons until the point‘ is reached where the
phase and a raf?nate phase and each of these
mixture is completely stabilized. The term
phases may ~then be separately. withdrawn.
“stabilize” as used herein is intended to mean
Continuous operations are well-known in the
that 'the mixture of silver salt, sulfuric acid,
art at the present‘time and may take the form
sulfonic 'acidand water will‘ not effect further
of one or more vessels or zones which do or do
substantial sulfonation of aromatic 'hydrocar
not contain packing material such as clays, gravel,
bons. Thus, in one speci?c embodiment of the
synthetic materials, etc. and/or fractionating
invention once the composition of the truly
means such as ba?ie plates, bubble trays and the
stabilized solution has‘ been determined, it may 00 like; Either concurrent or countercurrent ?ow
conveniently be prepared by mixing the proper
may be employed and the mixture may then be
proportions of silver salt, sulfuric acid, sulfonic
allowed to settle in either the same or different
acid‘and water;
'
,
The preferred sulfonic acid comprises an aro
matic sulfonic acid, although it is understood 55
that other sulfonic acids, such as aliphatic or
naphthenic sulfonic acids may be employed but
not‘ necessarily with equivalent results; Like
zones'in order to separate an extract layer and
a raf?nate layer. These layers are then sep
arately withdrawn.
.
~ After separation of these layers the hydrocar~
bons. may be recovered from the separating agent
by any suitable means". The preferred method
of recovering the hydrocarbon from the separat
wise; it is understood that the sulfonic acids may
also ‘contain other substituent groups such as 60 ing agent is to use a secondary solvent which is
hydroxyl, nitro,- carboxyl, alkoxy,"‘etc. but here
again not necessarily with equivalent results.
. In general it is preferred that the aromatic
immiscible with the separating agent and which
is lower or‘higher boiling'than the aromatic hy
drocarbon. The secondary solvent preferably
hydrocarbons used in preparing the sulfonic acid
comprises a hydrocarbon and particularly a
be of the same type as the aromatic hydrocarbon 65 paraf?nic hydrocarbon such as propane, butane,
which is to be separated in the process. Thus,
pentan'e,‘cetane, etc‘. . r»
I
"
for example, if benzene is the aromatic which it
‘Another suitableimethod of recovering the hy
is desired to separate from a mixture thereof
drocarbon‘from the separating agent is by reduc
with‘fother hydrocarbons, the' sulfonic acid‘ is
ing the pressure of‘ the extract phase. This
preferably benzene sulfonic acid. However, the 70 method may have particular application when
sulfonic acid of certain aromatic hydrocarbons
the absorption step of the process is conducted
are too insoluble in a mixture of silver sulfate
under high pressure.v .Another method which may
and sulfuric acid, with the result that there is
be employed is by heating the extract phase to
produced a solid mass which is not desirable for
a higher temperature in orderto distill the hy'—
use as a ‘separating agent. For example, with. 75 drocarbons. '. However, ‘this method must be used.
2,403,972’?
5
6
with caution since the higher temperatures will
mination that the recovered benzene was of 9'?
to 99%:purity
result in additional sulfonation of the aromatic
hydrocarbons although in some cases, it may
even be preferred to utilize the higher tempera
tures in order to sulfonate the aromatic hydro
carbons to the full extent of the separating agent
and thereby avoid any further sulfonation in the
further use of the separating agent within the
Example III
-
"_ -_
A silver sulfate sulfuric acid separating agent
containing 7.4% by volume of dissolved ‘benzene
was treated With a secondary solvent to'give the
following results:
,
t
‘
process. In still some other instances it may be
r
( Per _ cent“ by, 'vol
advantageous to employ both an increased tem l0
Secondary solvent -' 5’
perature and a reduced pressure in the desorp
tion or recovery stage.
The addition of water to the extract phase will
effect the separation of the hydrocarbons and
the separating agent. However, in some cases it 15 Normal hexadecan __
Methylcyclohexane“
probably will be necessary to subject the sep
‘;v_ ~~ ‘benzene, extract
'
'ed‘bythe‘secondé
ary solvent.
Normal heptane"
pentane _____ ._
i
-
i
.
‘50 i
I
'1' Z
‘
'58
arating agent to distillation, preferably under
vacuum, to recover the ?nal traces of hydrocar
bons therefrom.
It is also within the scope of the invention to 20
_
Example IVv
,
' Various silver sulfate sulful’iclacid separating
agents containing different concentrations - of
recover the hydrocarbons from the separating
dissolved benzene were prepared in order to de-.
agent by multiple stage desorption conducted at
termine the amount of hydrocarbon which may
be recovered therefrom. The secondary solvent
increasing temperature and/or decreasing pres
sure. In this manner, the ?rst portion so de
sorbed or released will be richer in one type of
and,
, employed in these tests was normal pentane
the results obtained are'asfollows:
compound than will be the subsequently desorbed
portions.
Per cent by'vol-
It is understood, however, that the recited
methods of recovering the hydrocarbons from the
separating agent will not necessarily be equiva 30
1;, -
~ _ _
Per cent by vol- >
_nme of'benzenev ume of benzene
in the separating extracted by nor;
agent
mal pentane
lent in their effectiveness and that the choice as
7. 40
to the particular method to be used will depend
primarily upon the type of hydrocarbons under
3. 70
1.36
66
‘
62
.
67
going treatment.
After separation of the hydrocarbons, the sep 35 It is thus seen that the percentage of benzene ex
arating agent may be removed from the process
tracted by normalpentane does not vary consid
but preferably is recycled to the extraction zone
erably with the concentration of benzene in the
for further use therein. When desired, the sep
arating agent may be utilized for the separation
Example V
of other hydrocarbon mixtures in the same or 40
separatingagent.
‘
.
'
.
'
A practically‘ saturated solution of. silverv sul
different zones.
fate in sulfuric acridlofv 790% concentrationg'which
The invention will be further illustrated in the
following speci?c examples of several operations
of the process.
Example I
A saturated solution of silver sulfate in sulfuric
acid of 85% concentration was prepared which
contained 3.6% of silver by weight. This separat-.
solution contained ‘ 7.9% a by weight of silver sui
fate, dissolved 24 ml. ‘of benzene perlOO ml. of
Water vin the form of ice and
45 separating agent.
hydrogen chloride were'added-to theseparating.
agent containing the dissolved benzene in order
to recover the benzene.
By this means 10 ml.
of benzene were recovered, which amounted to
ing agent dissolved 12.5 cc. of benzene per 100 cc. 50 1.35 mols of benzene recovered per mol of ‘silver.
of solvent. The cc. of benzene dissolved per mol
However, 14 ml. of benzene underwent’ sulfonaé
of silver is 211. The mols of benzene dissolved
tion and were not recovered.‘
'
' ~
per mol of silver amount to 2.37.
Example VI
By comparison, a 70% aqueous solution of
silver nitrate which contained 44.5% by weight of
silver dissolved only 3.3 cc. of benzene per 100 cc.
of solution. On the basis of mol of benzene dis
solved per mol of silver, the separating agent
containing silver sulfate is 60 times more effec
tive than the silver nitrate solution.
Example II
A mixture comprising 50% vby volume of ben
zene and 50% by volume of normal heptane was
treated with an equal volume of separating agent
65
Another practically saturated solution of silver
sulfate in sulfuric acid of 96% concentration,
which solution contained 15% by Weight of sil
ver sulfate, dissolved 66 ml. of benzene per 100
ml. of separating agent. Water in the form of
ice and hydrogen chloride were added to the sep
arating agent as before in order to recover the_'
benzene‘ By this means 43 ml- ‘of benzene .W?i‘él
recovered, which amounted to 2.49 mols of ben
zene recovered per mol of silver. However, 21
ml. of benzene underwent sulfonation and were
comprising sulfuric acid of 85% concentration
containing about 2.7 % of silver. This separating
not recovered. ‘.On the basis of the higher solvent
agent dissolved 10 cc. of benzene per 100 cc. of
recovered per mol of silver, the‘separating agent‘
comprising 15% by weight of silver sulfate in
capacity and the more effective mols of benzene
separating agent. However, this particular sep
arating agent was only 3/; saturated with silver‘ 70, sulfuric acid of 96% concentration is one of the
sulfate and therefore is not as effective as it
would be if it were completely saturated.
The dissolved benzene was recovered from the
separating agent by diluting the mixture with
Water. It was found by index of refraction deter
preferred solventsrof the-present invention. ' I ~' '
_' Example VII
A separating agent comprising 7.9% by weight-r
75 of silver-sulfate in sulfuric acid of-90% concert-w
2,403,972’?
7
8
tration dissolved 42 ml. of cumene per 100 {:nl. of
separating agent. Upon the addition of ice and
comprised the sulfonic acid of the same type of
hydrogen chloride, 24 ml. of cumene were recov
aromatic hydrocarbon as that being dissolved in
ered, which amounted to 2.05 mols cumene re
the separating agent.
covered per mol of silver.
agents except that the aromatic sulfonic acid
‘
.
18 mls. of cumene un
derwent sulfonation.
Ezrample VIII
7. Aseparating agent comprising 15% by weight
ofsilver sulfate in sulfuric acid of 96% concen 10
Ml. of aromatics dissolved per
100 ml. of separating agent i .
Aromatic
Separating
Separating agent’
agent concontaining sul
taming ben- ionic acid of the
tration‘ dissolved 116 ml. of cumene per 100 m1.
zene sulfonic
acid
ofwsepara‘t-ing agent. Upon the addition of ice
and hydrogen chloride, 63 ml. of cumene were
recovered, which amounted to 2.32 mols cumene
recovered per mol of silver. 53 mls. of cumene
Benzene _________________________ __
l9
Toluene.‘ _________ -_
________ _-
Mesitylene_____
Ethylbenzene
Cumene ____ -_
Example IX
Sulfuric acid of 96% concentration was re
_____________ __
19
Meta-xylene. _ . . ___
were sulfonated.
aromatic hydro~
carbon
Solid
25
20.
15
18
Solid
20.
19
24.
Amylbenzene
11
16.
Te alin ______ __
Amylnaphthalene _______________ -_
26
24
23.
Solid.
'
”
acted with various aromatic hydrocarbons for 16 20
hours at a temperature of 122° F. in the pres
As heretofore described, the separating ‘agents
ence of 1% of silver sulfate in order to sulfonate
containing the sulfonic acids of toluene, mesityl
the aromatic hydrocarbons and thereby stabilize
ene and amylnaphthalene proved unsuitableun
der the particular conditions of the above tests.
acid layer Was then separated from the undis
Example XII
solved aromatic hydrocarbon and was enriched
with 9.1% of silver sulfate. This solution was
A solution comprising 41 parts of sulfuricyacid
tested for its solvent power for benzene, toluene
of 79% concentration, 52 parts of benzene sul
and cumene,'and gave the following results:
fonic acid and '7 parts of silver sulfate was used
30 to separate a mixture containing various percent
ages of benzene in admixture with normal hep
Aromatic
‘ ~~~ *» h ~ ~' Mlrperi'lw
of~~
Mols 8f
0 arbon
so ven _
aroma 10
tane. The results of these tests are listed below:
“3:83 to
Aromatic
'
hydrocarbon
the separating agent. The sulfuric acid-sulfonic
.
stabilize the
separating
hydrocarbon
d-
1
, 155° W
d
.
Dis-
agent
solved
recovered
Recov- Sulion-
ered
per mol of
ated
silver
Percent by volume of
35
Benzene"-.Toluene._.__
25
‘ '
27
19
6
22-
5
Oumene_____
28
23
5
Toluene“...
63
54
9
Cumene__-_-
42
41
1
benzenein'g'
>
Percent by vol- ' '
‘
'
wume ofthe
2. 28
'
zene extracted
by equal
> 2.16
2. 01
‘
'
-'
7 available ben
Charge
Ra?inate
46
36
14
Extract
volume of sep.
agent
6. 03
3. 77
40
23
It is to benoted that the sulfonic acid of cumene
also exerts a solvent power‘of its ownsince the
9
4
1
2
separating agent comprising ‘silver sulfate; sul
furic acid, cumene sulfonic acid, and water, dis
solved higher portions of aromatic hydrocarbons
Enample XIII
._A silver sulfate-benzene sulfonic acid-sulfuric
than did the benzene sulfonic acid mixture. A
_
V
ErampleX
acid separating agent containing various percent
_v
The stabilized agents‘ containing benzene .‘s’ul
ionic and cumene sulfonicacid of Example IX 50
ages of benzene may be treated with normal pen
tane in order to recover thebenzene as is shown
in the following table:
'
'
were utilized to separate benzene from a mixture
containing equal amounts of benzene and hep
Per 8
tane with the following results:
Benzene
Aromatic hydrocarbon used to
stabilize the separating agent
um: (gtbggzggle
_
Percent of available
in the
separat.
gyeggra?tmglwith
11
ac vo ume
mg agent
‘
M1. per 100 m1. of solvent
Dis-
Recov-
Sulfon
solved
ered
ated,
of pentane
14. 4
59
7. 3
3. 4
56
50
57
1. 1
60
Benzene ......................... _-
17
16
1
Oumene __________________________ _ _
14
6
8
Example XI
I claim as my invention: '
1. A process for extracting anaromatichydro
carbon from a mixture additionally ‘containing.
65 other hydrocarbons but relatively ‘free of . ole?ns
The following table shows the results obtained
in dissolving various aromatic hydrocarbons in a
separating agent which had been prepared by dis
solving 10 parts by weight of silver sulfate in 90
parts by weight of sulfuric acid of 96% concen 70
tration and then stabilizing with benzene 'at‘a
temperature of 158 to 176° F. followed by exhaus
tive extraction of the dissolved unsulfonated ben
zene with normal pentane. Comparable solubili
benzene recovered
which comprises ‘contacting ‘said’. mixture with “a
separating agent prepared'by dissolving a silver
compound selected .fro'mi'the group'cdn'sisting'of
silver sulfate, silver oxide and silver ‘carbonat'efin
sulfuric acid and then reacting the resulting mix, .
ture with a hydrocarbongto produce a ?nal mix
ture containing the silver.vcompoundnv sulfuric
acid and a sulfonic acid.
, I
1;;
i, f
2.,,A process for extracting an aromatic hydro_-._
ties were also, determinedwith similar separating 75 carbon, from a mixture additionally;cqntainlng.
2,403,972
10
other hydrocarbons but relatively free of ole?ns
which comprises contacting said mixture with a
,
other hydrocarbons but relatively free of ole?ns
which comprises passing said mixture in contact
separating agent prepared by dissolving silver
with a solvent for the aromatic hydrocarbon com
sulfate in sulfuric acid and then reacting the re
sulting mixture with an aromatic hydrocarbon
to produce a ?nal mixture containing the silver
sulfate, sulfuric acid and an aromatic sulfonic
acid.
3. A process for extracting an aromatic hydro
carbon from a mixture additionally containing 10
prising sulfuric acid having dissolved thereina
other hydrocarbons but relatively free of ole?ns
silver compound selected from the group consist
ing of silver sulfate, silver oxide and silver car
bonate and an aromatic sulfonic acid, separating
an extract phase comprising the solvent and dis
solved aromatic hydrocarbon from the remain
ing hydrocarbons and recovering the aromatic
hydrocarbon from the extract phase.
9. The process de?ned in claim 8 further char
acterized in that the aromatic sulfonic acid is
formed by reacting sulfuric acid with an aromatic
sulfate in sulfuric acid and then reacting the
resulting solution with benzene to produce a ?nal 15 hydrocarbon which is the same as that extracted
from said mixture.
solution containing the silver sulfate, sulfuric
10. The process de?ned in claim 8 further char
acid and benzene sulfonic acid.
acterized in that said solvent comprises anrequi
4. A process for extracting an aromatic hydro
carbon from a mixture additionally containing
librium mixture of sulfuric acid,'aromatic sul
other hydrocarbons but relatively free of ole?ns 20 fonic acid and silver compound.
which comprises contacting said mixture with a
11. The process de?ned in claim Bfurther char
acterized in that said aromatic sulfonic acid com
solvent for the aromatic hydrocarbon compris
prises benzene sulfonic acid.
7
ing sulfuric acid having dissolved therein a silver
12. The process de?ned in claim 8further char
compound selected from the group consisting of
acterized in that said aromatic sulfonic acid com
silver sulfate, silver oxide and silver carbonate.
prises cumene sulfonic acid.
5. The process de?ned in claim 4 further char
13. A process for separating benzene from a
acterized in that said solvent contains a sulfonic
mixture additionally containing other hydrocar- .
acid.
bons but relatively free of ole?ns, which com
6. The process de?ned in claim 4 further char
acterized in that the sulfuric acid concentration 30 prises contacting said mixture with a solvent for
the benzene comprising an equilibrium mixture
is from 65 to 100 percent.
of sulfuric acid of from 65 to 100 percent concen
7. A process for extracting an aromatic hydro
tration, benzene sulfonic acid and silver sulfate.
carbon from a mixture additionally containing
14. A process for separating benzene from a
other hydrocarbons but relatively free of ole?ns
which comprises contacting said mixture with a
separating agent prepared by dissolving silver
which comprises passing said mixture in contact 35 mixture additionally containing other hydrocar
bons but relatively free of ole?ns, which comprises
with a solvent for the aromatic hydrocarbon
contacting said mixture with a solvent for the
comprising sulfuric acid having dissolved therein
benzene comprising an equilibrium mixture of
a silver compound selected from the group con
sulfuric acid of from 65 to 100 percent concentra
sisting of silver sulfate, silver oxide and silver car
bonate, forming during the extraction treatment 40 tion, cumene sulfonic acid, and silver sulfate.
15. A process for extracting benzene from a 7
an aromatic sulfonic acid, separating an extract
phase comprising the solvent, the dissolved aro
matic hydrocarbon and the aromatic sulfonic acid
mixture additionally containing other hydrocar
from the remaining hydrocarbons, separating the
contacting said mixture with a benzene solvent
bons but relatively free of ole?ns which comprises
aromatic hydrocarbon from the remainder of the 45 prepared by reacting to equilibrium sulfuric acid
with an excess of benzene, and saturating the re- ,
extract phase and returning said remainder of
sultant sulfuric acid-benzene sulfonic acid solu
the extract phase for reuse in extracting aromatic
tion with silver sulfate.
hydrocarbons from said mixture.
8. A process for extracting an aromatic hydro
BERNARD S. FRIEDMAN.
carbon from a mixture additionally containing 50
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