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Патент USA US3072578

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United States Patent
1C6
3,072,568
‘Patented Jan. 8, 1963 ,
1
2
3,072,568
hydrocarbons from gasoline boiling range aromatic and
nonaromatic hydrocarbon mixtures.
SELECTIVE SOLVENT EXTRACTION PROCESS
IN THE GAS-OIL RANGE
Charles J. Norton, Denver, Colo., assignor to Marathon
Oil Company, a corporation of Ohio
{ N0 Drawing. Filed Mar. 28, 1960, Ser. No. 17,786
,'
r
4 Claims. (Cl. 208-314)
There are many selective solvents for the extraction
It is a further object of the invention to provide a
cyclic process for the separation of aromatic hydrocar
bons in the gasoline boiling range aromatic and nonaro
matic hydrocarbon feeds.
_
These and other objects and advantages of the in~
vention may be accomplished 'by selective solvent ex
traction of a mixture of aromatic and nonaromatic hy
of specific hydrocarbon components from various hydro— 10 drocarbons with a selective solvent selected from the class
carbon systems, especially in the petroleum industry,
of beta-propiolactones and beta-propiolactams, which are
and it is ‘obvious that there is no one selective solvent
cyclic compounds formed from certain beta-hydroxy and
which is adequate for all purposes. In using a selective
beta-amino acids.
solvent for the extraction of certain hydrocarbons com
In practice the hydrocarbon mixture containing the aro
ponents from hydrocarbon mixtures, there are several 15 matic and nonaromatic hydrocarbons is thoroughly ad
different systems for the subsequent separation of the
mixed with the desired selective solvent by any suitable
solvent from the extracted hydrocarbon. In one sys
means, as for example, mechanical agitation or in a
tem, for example, extracted aromatic hydrocarbon is re
countercurrent extraction column. On settling the two
moved from the selective solvent by water washing, some
immiscible phases which are formed are then separated.
times known as springing. In another system, the ex 20 The upper or ra?inate phase has an appreciably reduced
tracted hydrocarbon may be removed from the selective
content ‘of the aromatichydrocarbons and the lower layer
solvent by distillation. Where it is possible to use ‘an
or phase contains the’ major amount of selective solvent
‘atmospheric distillation, when the character of both the
which is substantially enriched in the aromatic hydro
selective solvent and the aromtic hydrocarbon being ex
carbons from the feed and a limited amount of nonaro
tracted permits such a distillation, this is generally a 25 matic hydrocarbons. The ra?i'natelmay be recovered by
desired procedure since it is economical and both com
washing with a small amount of water or distillation
ponents are recovered in a dry state. With certain selec
to remove residual amounts of the solvent dissolved there
.\
tive solvents the water springing is impossible since the
solvent decomposes in the water. Such decomposition
not only destroys the selective solvent but the reaction
products may contaminate the hydrocarbon fraction ex
distilled to recover the aromatic free from the solvent.‘
the aromatic hydrocarbon. This, obviously, introduces
boiling range hydrocarbon‘ mixture.
in. The extract phase may’ then the atmospheri-cally
The recovered solvent may then be used for subsequent
extractions in a cyclic process. In modi?ed procedure
tracted.
the extract phase may be washed with another hydrocar
One commonly used selective solvent is gamma~butyr
bon feed mixture, which is in a different boiling range,
to provide a raf?nate containing the aromatic hydrocar
olactone, which may be used with 'or without water,
showing a certain selectivity for aromatics from hydro 35 bon from the ?rst feed mixture and which was originally
dissolved in the solvent. This ratlinate is readily sepa‘
carbon mixtures, among other systems. Gamma-butyr
olactone has a boiling point of about 204° C. which
rated by atmospheric distillation. The aromaticthydro
makes direct distillation of it from an aromatic extract in
carbon from the second feed (now dissolved in the sol
the gas-oil range impractical. Thus when using the
vent) has replaced the original aromatic hydrocarbon
gamma-butyrolactone to extract aromatic hydrocarbons
mixture in the solvent, and it may then be recovered by
from many hydrocarbon feeds, the gamma-butyrolactone‘
distillation from the solvent or by mass action of an
must be washed with water or other “antisolvent” from
additional treatment with more of the original gasoline
‘
_
Following the latter mentioned procedure,‘ a cyclic
is not simply recovered completely dry or completely free 45 process may be derived wherein the hydrocarbon in the
gasoline boiling range is initially passed through the se
of the antisolvent. Many other solvents have been pro
posed in various systems, but in only a few instances are
lective solvent until the selective solvent is essentially
a still further component into the system since the solvent
there any selective solvents which boil out of the gas-oil
range and which will provide su?icient extraction for an
saturated with the aromatic hydrocarbons. Then a mix
ture of hydrocarbons in a different boiling range may
50 be passed through the aromatic-solvent mixture so that
economical system.
‘
'
the aromatic hydrocarbons in the second hydrocarbon
In one of the embodiments of the invention, beta-pro
feed replace the aromatic hydrocarbons dissolved in the
piolactone has been found useful as a selective solvent
solvent until the aromatics from the second feed essen
for removing aromatic hydrocarbons from nonaromatic
tially saturate the selective solvent. The feed‘ mixtures
hydrocarbons in the gas-oil range. Furthermore, sub
stituted beta-propiolactones and beta-propiolactams of 55 are passedlthrough the. solvent phase until the aromatics
the general formula
in the incoming feed replaces the aromatics dissolved in
the solvent. By alternately passing these feeds through
the solvent, 1a cyclic process is provided wherein two dif
ferent raffinates may be recovered each of which con
60 tains aromatics‘ in a'different boiling range. This pro
wherein Y‘ is selected from the class consisting of O and
vides a system in which the aromatics are readily sepa}
N~—R2; R2 is selected from the class consisting of H and
rated from the nonaromatics and recovered by a simple
lower alkyl groups of from C1 to C5; and R1 is selected
distillation process. In such processes it may be neces
from the class consisting of hydrogen, halogen, nitrite,
amine, and lower alkyl groups of from C1 to C5; are 65 sary to add small amounts of the selective solvent to
replace the selective solvent dissolved in the ra?inate leavq
useful for selectively removing aromatic hydrocarbons
from nonaromatic hydrocarbons.‘
.
An important object of the invention is to provide
the separation of one class of hydrocarbons from dilfer- 7
ing the system.
'
' '
Example I
A portion of'beta-propiolactone was shaken with a
cut classes of hydrocarbons by means, of certain beta
50~50 toluene-n-heptane mixture having refractive‘ ‘index
propiolactones and beta-propiolactams. A further object 70 of 111320 1.4400 at a two. to oneoil-to-solvent ratio. The
of the invention is to provide a separation of aromatic
recovered raf?nate, which ‘is the solvent lean phase, was
3,072,568
4
3
When a similar amount of light catalytic cycle oil is
recovered from an extract (which is an aromatic rich
solvent phase). On washing the rat?nate with water to
remove the solvent from both of these phases, the follow
shaken in a ratio of 2.5 to 1 oil-to-solvent ratio with
gamma-butyrolactone, the following results:
ing products were obtained, and the composition of these
are indicated from refractive index curve of known mix-
5
tures of the two, as is well known procedure:
V01. percent of
m,”
Mixture
Vol. percent Aro-
Rainnate ____________________________________ __
Aromatic Extract ___________________________ __
matics
Volume of
n 25
LOCO
"
79
22
1. 4916
1. 5795
-
10
Ra?inate ____________________ __'_ ______ -_
Amman“ Extract --------------------- --
74.3
25'7
1.4278
1'4743
38.7
81-0
When the light catalytic cycle oil is extracted with a
2.5 to 1 oil-to—solvent ratio of 95% aqueous gamma
butyrolactone, however, the following results:
The solvent, however, has a boiling point which is es
sentially within the gasoline boiling range, that is about 15
162° C. The solvent, therefore, may not be recovered
from the aromatics by direct distillation, but the mass
action principle of exchange may be applied wherein a
hydrocarbon mixture in a different boiling range may be
passed through the aromatic-solvent mixture so as to 20
replace the aromatic dissolved in the solvent with the aro
matic in the second feed.
Volume of
LC 00
11,,“
Rqf?natc
88
1. 5013
Aromatic Extract ___________________________ __
12
1. 5892
From these results it is readily seen that the beta-pro
piolactone is far superior to either gamma-butyrolactone
Example II
or the aqueous gamma-butyrolactone in its selectivity
A portion of beta-propiolactone was shaken with a 25 for the aromatics. While its capacity is essentially the
same as 95% aqueous gamma-butyrolactone, it is su
reformatephaving a refractive index of nD2° 1.4542 at a
perior in its selectivity of the aromatics. Further, the
two to l oil-to-solvent ratio. The primary rat?nate, that
beta-propiolactone boils at 162° making direct distilla
is the solvent-lean phase, and a primary extract phase,
solvent, the following products were obtained:
tion from the extract phase feasible. On the other hand
the gamma-butyrolactone boils at 204° C. and therefore
must be washed from the extract with water.
Vol. per
cent of
I claim:
1. A process of obtaining an extract rich in aromatic
hydrocarbons from a mixture of aromatic and non-aro
that is the solvent-rich phase, were separated. On wash
ing the samples of these phases with water to remove the
m."
Reformate
Primary Rat?nate ___________________________ ._
Primary Aromatic Extract __________________ __
89.2
10. 8
35 matic hydrocarbons by means of a phase separation com
prising extracting said hydrocarbon mixture with beta
propiolactone, and separating the aromatic rich extract
phase from the ra?inate phase.
1. 4496
1. 4921
2. A process of obtaining an extract rich in aromatic
Example II]
40 hydrocarbons from a mixture of aromatic and non-aro
matic hydrocarbons in the gas-oil range by means of a
If the primary extract obtained from Example II is
phase separation, comprising extracting said hydrocarbon
shaken with a light catalytic cycle oil at about a one to
mixture with beta-propiolactone as the selective solvent,
and then separating the aromatic rich extract phase from
two primary extract phase to light catalytic cycle oil, a
secondary raf?nate and a secondary extract phase result.
On washing these two phases with water to remove the 45 the raf?nate phase.
3. A process for obtaining an extract rich in aromatics
solvent from the phases, the following products were
from a mixture of aromatic and non-aromatic hydrocar
obtained:
bons in the gas-oil range by means of a phase separation
.
"D20
comprising extracting said hydrocarbon mixture with
Secondary raf?nate _______________________ __ 1.5000
about a 2 to 1 oil-to-solvent ratio of beta-propiolactone as
Secondary aromatic extract ________________ __ 1.5570 50
When refractive indices of these aromatic extracts are
a solvent, and then separating the aromatic rich solvent
phase from the ra?inate phase.
compared, it is apparent that the gasoline range aromatics
may be displaced from an extract phase by higher boil
ing aromatics from a gas-oil hydrocarbon mixture. After
4. A process of obtaining an extract rich in aromatics
from a mixture of aromatic and non-aromatic hydrocar
the exchange has occurred, the low boiling aromatics
which are then in secondary raf?nate (along with higher
boiling nonaromatics) may be removed by direct distilla
said hydrocarbon mixture having a ?rst boiling range
bons in the gas-oil boiling range comprising extracting
with beta-propiolactone as the selective solvent to form an
extract rich in the aromatics in the gas-oil boiling range,
extracting the resultant aromatic-rich solvent phase by
tion. The low boiling aromatics are recovered as the
overhead, and solvent may be recovered from the sec 60 adding a mixture of aromatic and non-aromatic hydro
carbons in a second boiling range different from boiling
ondary extract phase by direct distillation.
' range of said gas-oil hydrocarbon mixture to thereby re
Example IV
place the aromatics of the gas-oil range dissolved in the
solvent, and then distilling the resultant mixture contain
ing aromatics from the gas-oil range mixture and the non
aromatics from the different boiling range mixture to
thereby recover the gas-oil aromatics.
. A portion of beta-propiolactone solvent is shaken with
a light catalytic cycle oil (LCCO) in a ratio of about
2.5 to 1 volume of oil-to-solvent and raf?nate and extract
phases result. The two phases were separated and on
washing with water to remove the solvent from these
phases the following products were obtained:
70
Volume of
L000
Raf?nate ________________ __
Aromatic Extract _______ __
88
12
111,20
1. 4990
1. 5988
75
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,727,848
2,831,905
2.910.518
Georgian _____________ __ Dec. 20, 1955
Nelson _______________ __ Apr. 22, 1958
Lampert et a1 __________ __ Oct. 27, 1959
2,917,562
2,933,448
Templeman et al _______ __ Dec. 15, 1959
Morin et al ___________ __ Apr. 19, 1960
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