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Патент USA US2405258

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Patented Aug. 6, 1946
2,405,258
UNITED STATES PATENT OFFICE
2,405,258
PROCESS FOR DESULPHURIZING
HYDROCARBONS
George R. Lake, Long Beach, Calif., asslgnor to
Union Oil Company of California, Los Angeles,
Calif., a corporation of California
No Drawing. Application December 8, 1942,
Serial No. 468,220
17 Claims. (01. 202-42)
'
2
aforementioned change will be referred to as
tion.
An object of the present invention is to further
the progress in preparing pure relatively sulphur
free compounds from heterogeneous hydrocarbon 10
mixtures, using in this particular case a method
115
20
25
and sulphur compounds.
A particular object of‘ my invention is to sep
arate non-aromatic hydrocarbons and sulphur
aromatic hydrocarbons by dis
The fractional
ture results in distilling
30
distillation residue ‘an aromatic hydrocarbon 85
fraction relatively free from non-aromatic hy
drocarbons and sulphur compounds.
The invention comprises adding to such hy
drocarbon fractions from which it is desired to 40
segregate a speci?c hydrocarbon or hydrocarbon
fraction, a substance or a mixture of substances
hereinafter disclosed having a preferential ailin
ity in the vapor state for one or more components
contained in the fractions, thus causing a dis 45
turbance of the vapor pressure equilibrium that
formerly existed in the fraction in such manner
that the partial vapor pressure or fugacity of at
su?iciently to permit its separation by controlled
fractional distillation. This type of fractional
distillation will be referred to hereinafter as azeo
tropic distillation and the substance or substances
which are added to the fraction which e?ect the
50
aromatic hydrocarbons
and yet contains sulphur, the azeotropic distilla
tion to remove sulphur from the remaining hy
drocarbon mixture, such as one containing par
a?ins and ole?ns and naphthenes, orv ole?ns and
naphthenes or mixtures of para?ins, ole?ns and
65 naphthenes may be accomplished by azeotropic
2,405,258
4
toluene, xylene, etc, boiling range since it is pref
distillation in which case the distillation residue
azeotrope former which has
a boiling point of not more than 50° F. difference
- erable to employ an
may consist of the relatively more aromatic hy
drocarbons, i. e. the hydrocarbon which does not
form an azeotrope with the azeotrope former or
f0rms a higher boiling azeotrope therewith. In I."
some cases, it may be desirable to remove only the
from the average boiling point of the hydro
carbon stock.
I have found that acetone is particularly e?i
‘cient for desulphurizing complex hydrocarbon
sulphur compounds from a hydrocarbon or hy
fractions containing benzene and sulphur com
drocarbon mixture.
This may also be accome
pounds and also non-aromatic hydrocarbons
plished by azeotropic distillation but in such cases
boiling between about 150 and 200° F. to produce
it may be necessary to more carefully control the
distillation to prevent substantial amounts of an
azeotrope or azeotropes of the hydrocarbons from
also distilling overhead in admixture with the sul
substantially pure benzene.
Acetone is an un
usually efficient azeotrope former for separating
benzene as it does not form an azeotrope with the
benzene. Substantially pure benzene is required
in the production of chemical compounds or de
The type of distillation to be used depends 15' rivatives such as for producing phenols which
the a‘ze'ot'ro‘p'e
' somewhat on the quantity of
are used in making plastics, and ethyl benzene
phur compounds.
.
.
former used. I may take any proportion of the
which may be converted to styrene and employed
hydrocarbon fraction to the added mixture that
in making synthetic rubber.
I desire, depending on the ef?ciency of the oper
I have also found that methyl ethyl ketone,
20
ation or the purity of the product desired,~ahd
preferably containing water is an extremely e?i
the technique to be usedin the distillation. The
cient azeotrope former for separating pure tolu
proportion of the azeotrope former may readily
ene from complex hydrocarbon fractions con
be adjusted on an ideal point, the de?nition of
this point again depending on whether I desire
taining toluene, non-aromatic hydrocarbons and
sulphur compounds boiling between 200 and 240°
the portion highin aromaticity to remain as 25 F. The production of substantially pure toluene
bottoms in the distillation column in a practi
cally pure state, i. e. free from non-‘aromatic
is highly important when it is to housed in the
manufacture of explosives by nitrating the tolu
hydrocarbons and sulphur compounds, or wheth
ene since small amounts of impurities seriously
er I wish to distill'a portion of the non-aromatic
impair the nitration process. Since this azeo
hydrocarbons, leaving a portion of the non-aro 30 trope former does not form an azeotrope with
matic hydrocarbons as bottoms together with
toluene but forms an azeotrope with only the
aromatic hydrocarbons.
Also, the distillation
non-aromatic hydrocarbons and sulphur oom- “
temperature and amount of. aze'otrop'e former
may be adjusted to effect the distillation of all of
pounds‘ in the mixture, the toluene will remain
as a distillation bottoms substantially free from
azeotrope former.
While the foregoing description of my inven
tion has been made with particular reference to
the use of ketones for desulphurizing hydrocar
the non-‘aromatic hydrocarbons and sulphur
compounds together with a portion of the aro
matic hydrocarbons. » In other words, the e?i
ciency of separation of the aromatic from non
aromatic hydrocarbons is ‘dependent upon the
bons, other azeotrope formers may be used for
a this purpose, it being understood that the choice
proper adjustment of the amount ‘of 'azeotro-pe
former used since a small amount may result in
of azeotrope former for the most efficient opera
tions will depend upon the character and boiling
range of the stock undergoing treatment. Ex
incomplete separation of the non-aromatic hy
drocarbons while the use of an excess of the
azeotrop'e former together with a relatively higher
distillation temperature may "cause distillation
45
amples of such azeotrope formers include alco
hols such as methyl, ethyl, propyl, butyl alcohol,
fatty acids such as acetic, ‘propionic, butyric,
valeric acid, polyglycols such as mono-, di-, tri-,
of a portion of the aromatic hydrocarbons, par
ticularly in the case where ‘the azeotrope former
also forms an azeotrope with the aroma-tic hy
tetra~, hexa-, mona-ethylene glycol, propylene
drocarbons. In the foregoing separations, the
and di-propylene glycol, ethers and esters of
50
sulphur compounds contained in the Stock will
such polyglycols, phenolic compounds such as
be distilled together with the non-aromatic hy
phenol, resorcinol, naphthol, saturated hetero
drocarbons or if desired the azeotropic distilla
cy'clic compounds of four carbon atoms such as
tion may be carried out to distill overhead sub
dioxane, morpholine, di-oxolane, nitrogen bases
stantially only sulphur compounds together with
such as picoline, pyridine, quinoline, 'r‘nonoe, di-,
azeotrope former. The latter is particularly de
tri-amylamine, nitroparaf?ns such as nitro
sirable in those cases where the stock is "essen
ethane, nitromethane and nitropropane.
tially aromatic containing only small amounts of
Sulphur compounds which may be removed
para?‘in, ole?n and/or naphthene hydrocarbons.
from hydrocarbon fractions by aze'otropic dis
I prefer, however, to carry out the distillation so
tillation, of course, include those which form
that at least a portion of the relatively less aro 60 azeotropes with the azeotrope former or those
matic hydrocarbons will also ‘distill overhead
together with the sulphur compounds.
which in conjunction with relatively nonearo
matic hydrocarbons form an azeotrope with the
I have found that ketones, such as aliphatic
azeotrope former. With some stock's, it is merely
ketones, for example, acetone, methyl ethyl ke
possible to remove by azeotropic distillation only
65
tone, diethyl ketone, methyl isopropyl ket‘one,
a portion of the sulphurrcompounds contained
diacetyl, acetonyl acetone and also ‘the cyclic
in the stock, leaving a portion of the sulphur
ketones, for example, cyclohexanone, methyl
compounds in the residue together with the rel
phenyl lieton , etc., are particularly emcient in
atively aromatic hydrocarbons. Nevertheless, I
separating substantially pure aromatic hydro
have found that the sulphur compounds which
carbons from complex hydrocarbon fractions of 7,0 are removable as overhead products either alone
relatively narrow boiling range containing sul
orv in admixture with relatively non-aromatic
phur compounds. The choice-of the azeotrope
hydrocarbons, together with the azeotro'pe form
former to be employed will‘generally depend upon
er, are not ordinarily removable from the stock
the characteristics of the hydrocarbon stock to,
by ordinary acid treatment. I have'also found
be ‘treated, i. e. whether‘ it is in the benzene,
2,405,258
water to dissolve and remove ‘substantially all of
the acetone contained therein. The 25 parts of
thus extracted oil had a sulphur content of about
by ‘ordinary acid treatment or extraction with
12%.
solvents either in the liquid phase or vapor phase.
The reasons that certain sulphur compounds
contained in stocks are removable as overhead
products together with azeotrope former by azeo
tropic distillation while other types of sulphur
sulphuric acid per barrel of bottoms and then
10 neutralized with caustic alkali which resulted in
compounds do not distill overhead with the azeo
producing a fraction having 0.014%
trope former and relatively non-aromatic hydro
carbons is not too clear. ‘However, one explana
tion may be found in the fact that certain sul
phur compounds such as thiophanes behave like
non-aromatic hydrocarbons such as parai?ns 15
while other sulphur compounds such as thio
phenes beh'ave like aromatic hydrocarbons.
Thus, when a stock contains a mixture of such
tures of sulphur compounds, it is nevertheless
possible to remove substantially all of the sul
phur compounds contained in the stock by a com
bination of steps involving ?rst an azeotropic
Example 2
1000 parts of the same hydrocarbon stock de
sulphur compounds, the sulphur compounds
which behave like non~aromatic hydrocarbons 20
are removed overhead by azeotropic distillation
together with the relatively non-aromatic h'ydro
carbons, while sulphur compounds which behave
like aromatic hydrocarbons remain in the residue
together with the aromatic hydrocarbons. In
those cases where the stock contains such mix
‘
The undistilled bottoms of the azeotropic dis
tillate had a sulphur content of 0.12%; This
fraction was then treated with 20 pounds of 98%
scribed in Example 1 and having a boiling range
of 172-225° F. was fractionated in a fractionating
column at a temperature of about 175° P. which
resulted in distilling overhead 140 parts of the
hydrocarbon fraction having a sulphur content
of about 1.5% and leaving about 860 parts of an
undistilled bottoms having a sulphur content of
about 0.10%.
The 140 parts of overhead fraction was con
densed and then mixed with about 110 parts of
acetone and the mixture was distilled at a tem
perature of 130° .F. and‘ at atmospheric pressure
distillation as described herein to remove over
head sulphur compounds either together withor
without the relatively non-aromatic hydrocar
bons and azeotrope former and second, an acid
treatment or extraction of the residue with a 35 traction with sufficient water, the fraction had a
solvent to remove the remaining portion of the
sulphur content of about 15%. The undistilled
sulphur compounds from the aromatic hydrocar
bottoms was substantially pure benzene having a
bons. Selective solvent extraction processes are
sulphur content of 0.04% and amounted to about
120 parts.
well known and need not be described further
herein. Processes of this character are described 40
The 860 parts of undistilled bottoms of the ini
in the McKittrick 2,162,963 and Roelfsema
tial fractionation was distilled at a temperature
2,069,329 patents. In general, the sulphur com
of about 190° F. which resulted in distilling over
pounds which may be removed by azeotropic dis
head about 800 parts of substantially pure ben
tillation include the th'iophanes, alkyl sulphides
zene having a sulphur content of 0.04%, leaving
and perhaps mercaptans and disulphides, while 45 as undistilled bottoms a fraction consisting main
those which are not separable by azeotropic dis
tillation or remain in the aromatic residue of an
azeotropic distillation process include the thio
phenes and thionaphthenes.
'
tropic distillation to produce about 920 parts of
Other objects, features and advantages of my 50 a benzene containing about 0.04% sulphur.
invention will be apparent to those skilled in the
blend was then treated with about 10 pounds of
98% sulphuric
art from the following examples of the invention
which are not to be taken as limiting but as illus
trative of my invention.
'
Example 1
In order to compare the above results with or
250 parts by volume of acetone were mixed with
1000 parts by volume of a. hydrocarbon fraction
obtained from coal tar having a boiling range of
approximately 172° F. to 225° F. and consisting of 60
approximately 92% benzene, 5% toluene, 1.5%
dinary acid treatment of the same stock, a por
tion of the same stock described above was treat
ed with about 20 pounds of 98% sulphuric acid
per barrel of stock and neutralized with caustic
alkali. The thus treated product showed a sul
phur content of about 0.20%.
sulphur. compounds and 1.5% of non-aromatic
hydrocarbons such as paraf?ns, naphthenes and
Example 3
ole?ns. The hydrocarbon fraction had a sulphur
A portion of the same stock described in the
content of 0.29% as determined by the lamp sul 65
preceding examples was fractionated to produce
phur method. The mixture of acetone and hy
a benzene fraction substantially free from toluene
drocarbon fraction was distilled in a fractionat
and having a boiling range of about 172° F. to
ing column at a temperature of about 130° F. and
at atmospheric pressure. This resulted in dis
180° F. This fraction contained about 0.29% sul
tilling overhead substantially all of the ‘acetone 70 phur. 600 parts of this fraction was then mixed
and approximately 25 parts of the hydrocarbon
with 1000 parts of methanol and the mixture was
distilled at a temperature of about 138° F. The
fraction which‘ consisted of approximately 15
parts of non-aromatic hydrocarbons and 10 parts
distillate was separately collected in about 4%
of sulphur compounds. This mixture was con
outs and each fraction was analyzed. Methanol
densed and subsequently extracted with sui?cient 75 distilled overhead with each out until all of the
hydrocarbon fraction had distilled overhead,
2,405,255
leaving substantially pure methanol as a distilla
tion residue. The methanol was removed from
each cut by extraction with sufficient water and
each hydrocarbon fraction was separately an
alyzed for sulphur content with the following re
sults:
The ?rst 5% of distilled oil showed a sulphur
content of about 2.0%; the next 5% showed a
sulphur content of 0.31%, while the next 80%
of distilled oil had an average sulphur content
of 0.06%. The next 7% of oil had a sulphur
content of 0.56% while the last 3% of oil con
sulphur compounds comprising thiophanes and
thiophenes to separate thiophanes therefrom,
which comprises distilling said aromatic hydro
carbon fraction in the presence of a su?icient
amount of a polar organic azeotrope former hav
ing a boiling point of not more than 50° F. dif
ference from the average boiling point of said
fraction to vaporize the sulphur compounds com
prising thiophanes together with azeotrope
former, thereby leaving aromatic hydrocarbons
and thiophenes in the residue substantially com
pletely separated from thiophanes.
5. A process for the treatment of a toluene
fraction containing a mixture of sulphur com
tained 3.0% sulphur.
The foregoing experiment indicates that the
pounds comprising thiophanes andthiophenes
stock contained at least two types of sulphur com
pounds, one of which was distilled overhead in
to separate thiophanes therefrom, which com
prises distilling said toluene fraction in the pres
the ?rst few percent of azeotropic distillate, while
the other type of sulphur compound remained as
ence of a sufficient amount of a polar organic
azeotrope former having a boiling point of not
more than 50° F. difference from the average boil
a distillation bottoms in the last 3% of oil which
was subsequently distilled as an azeotrope with 20 ing point of said fraction to vaporize the sulphur
the methanol. These sulphur compounds could
compounds comprising thiophanes together with
be recovered from the oil associated therewith by
well known methods.
The foregoing description of my invention is
azeotrope former, thereby leaving toluene and
thiophenes in the residue substantially completely
separated from said thiophanes.
6. A process for the treatment of a benzene
not to be taken as limiting my invention but only
fraction containing a mixture of sulphur com
as illustrative thereof since many variations may
pounds comprising thiophane and thiophene to
be made by those skilled in the art without de
separate thiophane therefrom, which comprises
parting from the scope of the following claims.
distilling said benzene fraction in the presence of
I claim:
1. A process for fractionating a mixture of sul 30 a su?icient amount of a polar organic azeotrope
former having a boiling point of not more than
phur compounds of the type contained in a coal
tar fraction boiling in the benzene boiling range
50° F. difference from the average boiling point
and comprising thiophane and thiophene which
comprises distilling said mixture of sulphur com
pounds in the presence of a suiiicient amount of
of said fraction to vaporize thiophane together
with azeotrope former, thereby leaving benzene
and thiophane in the residue substantially com
acetone adapted to form an azeotrope with thio
pletely separated from thiophane.
phane thereby vaporizing that portion of said
sulphur compounds comprising thiophane to
‘7. A process for the treatment of a hydrocar
bon fraction containing non-aromatic hydrocar
gether with acetone and leaving the remaining
portion of said sulphur compounds comprising
thiophene in the residue substantially completely
separated from thiophane.
40
2. A process for fractionating a mixture of sul
phur compounds comprising thiophanes and thio
phenes, which comprises distilling said mixture
of sulphur compounds in the presence of a suf
?cient amount of a polar organic azeotrope
former having a boiling point of not more than
50‘! F. difference from said mixture of sulphur
compounds and adapted to form an azeotrope 50
bons, aromatic hydrocarbons and a mixture of
sulphur compounds comprising thiophanes and
thiophenes to separate non-aromatic hydrocar
bons and thiophanes from aromatic hydrocar
bons and thiophenes, said non-aromatic and aro
matic hydrocarbons ordinarily distilling from the
hydrocarbon fraction in the same temperature
range as said aromatic hydrocarbons distill
therefrom, which comprises distilling said hy
drocarbon fraction in the presence of a sufficient -
with said thiophanes, thereby vaporizing that
amount of a polar organic azeotrope former hav
ing a boiling point of not more than 50° F. differ
ence from the average boiling point of said hy
portion of said sulphur compounds comprising
drocarbon fraction to vaporize substantially all
thiophanes together with azeotrope former and
leaving the remaining portion of said sulphur
of said non-aromatic hydrocarbons and said thi
ophanes together with azeotrope former, there
compounds comprising thiophenes in the residue 55 by leaving said aromatic hydrocarbons and said
thiophenes in the residue substantially com
substantially completely separated from thio
pletely separated from non-aromatic hydrocar
phanes.
3. A process for fractionating a mixture of sul
bons and thiophanes.
8. A process according to claim '7 in which said
phur compounds of the type contained in a coal
tar fraction boiling in the benzene boiling range 60 polar organic azeotrope former comprises a ke
and comprising thiophane, and thiophane which
tone.
9. A process for the treatment of a toluene
comprises distilling said mixture of sulphur com
fraction containing non-aromatic hydrocarbons
pounds in the presence of sufficient amount of
and a mixture of sulphur compounds comprising
a polar organic azeotrope former having a boil
ing point of not more than 50° F. difference from
thiophanes and thiophenes to separate non-aro
the average boiling point of said mixture of sul
matic hydrocarbons and thiophanes therefrom,
phur compounds and adapted to form an azeo
said non-aromatic hydrocarbons and sulphur
trope with thiophane, thereby vaporizing that
portion of said sulphur compounds comprising
compounds ordinarily distilling from the hydro
carbon fraction in the same temperature range
thiophane together with azeotrope former and 70 as said toluene distills therefrom, which com
leaving the remaining portion of said sulphur
prises distilling said toluene fraction in the pres
compounds in the residue substantially complete
ence of a sufiicient amount of a polar organic
azeotrope former having a boiling point of not
ly separated from thiophane,
4. A process for the treatment of an aromatic
hydrocarbon fraction containing a- mixture of
more than 50° F. difference from the average
2,405,258
i0
boiling point of said fraction to vaporize sulphur
compounds comprising thiophanes and non-aro
matic hydrocarbons together with azeotrope
former, thereby leaving toluene and sulphur
compounds comprising thiophenes in the residue
substantially completely separated from non
aromatic hydrocarbons and sulphur compounds
matic hydrocarbons.
10. A process according to claim 9 in which
said polar organic azeotrope former is methyl
14. A process according to claim 13 in which
said small proportion of sulphur compounds
comprising thiophenes is separated from said
matic hydrocarbons and thiophanes and cori~
taining a small proportion of sulphur compounds
comprising thiophenes and subsequently sepa
rating said small proportion of sulphur com
pounds comprising thiophenes from said aro
comprising thiophanes.
10 aromatic hydrocarbons by treatment with sul
ethyl ketone.
phuric acid.
15. A process according to claim 13 in which
said small proportion of sulphur compounds
drocarbons and a mixture of sulphur compounds
comprising thiophenes is separated from said
comprising thiophane and thiophene to separate
non-aromatic hydrocarbons and thiophane 15 aromatic hydrocarbons by extraction with a se
lective solvent for said thiophenes.
therefrom, said non-aromatic hydrocarbons and
16. A process for producing substantially pure
sulphur compounds ordinarily distilling from the
toluene from a hydrocarbon fraction containing
benzene fraction in the same temperature range
toluene, non-aromatic hydrocarbons and a mix
as said benzene distills therefrom, which com
ture of sulphur compounds comprising thio
prises distilling said benzene fraction in the pres
11. A process for the treatment of a benzene
fraction comprising benzene, non-aromatic hy
phanes and thiophenes, said non-aromatic hy
ence of a su?‘lcient amount of a polar organic
drocarbons and mixture of sulphur compounds
azeotrope former having a boiling point of not
comprising thiophanes and thiophenes distilling
more than 50° F. difference from the average
in the same temperature range as toluene, which
boiling point of said benzene fraction to vaporize
thiophane and substantially all of said non-aro 25 comprises distilling said hydrocarbon fraction in
the presence of sui?cient amount of methyl ethyl
matic hydrocarbons together with azeotrope
ketone to vaporize substantially all of said non
former, thereby leaving benzene and thiophene
aromatic hydrocarbons and said thiophanes to
in the residue substantially completely separated
from thiophane and non-aromatic hydrocarbons.
gether with methyl ethyl ketone, thereby leaving
12. A process according to claim 11 in which 30 toluene in the residue substantially completely
separated from non-aromatic hydrocarbons and
said polar organic azeotrope former is acetone.
thiophanes and containing small amounts of sul
13. A process for the treatment of a hydro
carbon fraction containing non-aromatic hydro
carbons, aromatic hydrocarbons and a mixture
of sulphur compounds comprising thiophanes
and thiophenes to separate sulphur compounds
35
phur compounds comprising thiophenes and sub
sequently treating said toluene containing small
amounts of sulphur compounds comprising thio
phenes to separate said small amounts of sulphur
compounds comprising thiophenes from said
and non-aromatic hydrocarbons from aromatic
toluene.
hydrocarbons contained in said hydrocarbon
17. A process for producing substantially pure
fraction, the non-aromatic and aromatic hydro
carbons and said sulphur compounds ordinarily 40 benzene from a hydrocarbon fraction containing
benzene, thiophane, thiophene and non-aromatic
all distilling from said hydrocarbon fraction in
hydrocarbons which distill in the same temper
the same temperature range, which comprises
ature range as benzene, which comprises dis
distilling said hydrocarbon fraction in the pres
tilling said hydrocarbon fraction in the presence
ence of a su?icient amount of a polar organic
azeotrope former having a boiling point of not 45
'
of acetone to vaporize sub
more than 50° F. difference from the average
boiling point of said hydrocarbon fraction to
vaporize substantially all of said non-aromatic
hydrocarbons and the sulphur compounds com
prising thiophanes together with said polar or 50
stantially all of said non-aromatic hydrocarbons
and said thiophane together with acetone, there
by leaving a mixture of benzene and thiophene in
ganic azeotrope former, thereby leaving said
the residue substantially completely separated
irom non-aromatic hydrocarbons and thiophane
and subsequently treating said mixture of ben
aromatic hydrocarbons in the residue substan
tially completely separated from said non-aro
zene and thiophene to separate said thiophene
from said benzene.
GEORGE R. LAKE.
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