close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2407387

код для вставки
2,407,386
Patented Sept. 10, 1946
UNITED STATES PATENT OFFICE
2,407,386
RECOVERY OF SECONDARY OLEFINS FROM
ACID \EXTBACTS
Harold W. Scheeline, Elizabeth, N. J., assignor
to Standard Oil Development Company, a cor
poration of Delaware
Application February 14, 1942, Serial No. 430,872
3 Claims.
I
This invention relates to improvements in the
separation and recovery of secondary ole?ns
from mixtures of ole?ns and saturated hydro
carbons which are associated in gaseous and
(01. 260-677)
2
product as to render the process unpro?table.
In addition, in cases where butenes are to be
subjected to pyrolysis, as in butadiene manu-.
facture, dilution with para?ins causes (1) loss
5 of the para?in, which is a valuable material in
itself (e. g. isobutane) and (2) dif?culty in re
covering the desired product after pyrolysis.
Pure ole?nic hydrocarbons have been sepa
rated from naphthas containing the ole?ns di
light liquid hydrocarbon mixtures and more particularly the separation of ole?ns having from
3 to 5 carbon atoms to the molecule from mixtures of hydrocarbons or mixtures consisting
mainly of ole?ns and saturated hydrocarbons.
The separation of ole?ns by fractional distillae' 10 luted with paraf?nic hydrocarbons of approxi
tion from saturated hydrocarbons having the
mately the same boiling point by treating the
same number of carbon atoms to the molecule,
naphtha with sulfuric acid under such conditions
as in the case of mixtures produced by cracking
of acid strength, temperature, etc., as to selec
or pyrolysis of petroleum oils or other bituminous
tively extract the ole?ns into the acid phase.
materials, is very diiiicult. In most cases, it is 15 The acid extract containing ole?ns may then be
impossible for all practical purposes, for example,
subjected to conditions whereby the ole?n is re
to fractionally separate by distillation propylene
‘covered and the acid returned to the extraction
boiling at —48.2° C. from propane which boils at
step- This has been done heretofore by Suitable
—45.0° C. The separation of 4 carbon atom oledilution with water followed by steam stripping.
?ns and saturated hydrocarbons that are found 20
It is W611 known that Sulfuric acid may readily
in a cracked hydrocarbon mixture is still more
poiymeriZe the ole?ns and 15‘ vis Well known that,
di?icult, as they are more numerous‘ and have
the ole?n-sulfuric acid reaction products
the following boiling points:
Isobutane
'
are heated without sufficient dilution, polymer
Bomng Points 0 C
ization and secondary oxidation reactions occur,
_
‘_1’0? ' 25 such as the formation of_tar _or carbon, with
lsobutnne """""""""""""""""""""" "
__6'
1_bute;1e "* ““““““““““““““““““ "
.
----------------------- -'
6'1
_
'
Butadlene ““““““ ". ---------------- "
—4"75
n'Buta'ne --------------------------- —-
"0-6
Z'butene' tt'a’ns --------------------- -~
"IO-9g
decomposition of the sulfurlc ac1d to sulfur diox
ide and water.
conditions
It is also known that under these
excess
or
uncombined
sulfuric
increases the formation of polymers.
acid
Also, the
3o disadvantage of extract dilution and steam strip
ping process is in the expense involved in han
z'butene’ C15 ------------------------- -- +33“
The 5 carbon atom group of pentanes and pen-
dling, reconcentrating and reducing the carbon
Content of the 11013 dilute 510? acid'
tenes is even more complex and the separation
According to the present invention the sec
of these ole?ns from the associated saturated 350M131? ole?ns may be recovered from Ole?n
hydrocarbons by‘physical means has heretofore
sulfuric acid solution without any substantial
not been accomplished.
loss due to polymerization and secondary oxida
There are many chemical processes in which it
tion and without the dilution or heating of the
is a decided advantage to use a substantially pure
acid extract. The following description will be
ole?n, unmixed with inert diluents, such as sat- 40 related to normal butene separation but the pro
urated hydrocarbons. For example, in chemical
cess described will also have application to the
reactions with the gaseous ole?ns in which presrecovery of other secondary ole?ns, such as pro
sure is advantageous, the effective pressure is
pylene, normal amylene, etc.
normally the partial pressure of the reactive
vSulfuric acid of about 70% to 90%, preferably
ole?n in the mixture. In such cases, substan- 45 83%, concentration is used to absorb the secon
tially pure ole?ns permit much lower pressures
dary ole?ns. This may be done at an elevated
to be employed and less gas to be compressed
pressure in the liquid phase or at a lower pres
than in the case of gas mixtures poor in reactive
sure in the gas phase.
~
ole?n. Also, in many cases the ole?n reaction
When normal butenes react with H2804, the
may be reversible, the proportion of the desired 50 resulting extract has been found experimentally
product being dependent upon the concentrato contain some butene as such, some as secon
tion of the reactive ole?n in the mixture. In
dary butyl alcohol, and some as mono-or dibutyl
such cases, the dilution of the ole?n with an
sulfate. The extract is found to exert a consid
inert diluent, such as a saturated hydrocarbon, 5 erable vapor pressure of normal butylene, de
may so affect the yield of the desired reaction 5 pending on the concentration of hydrocarbon
2,407,386
3
4
and acid in the extract and on the temperature.
4 is provided and cooling coil 5 to regulate the
temperature. The mixture of sulfuric acid and
the hydrocarbons is then passed through pipe 8
Extracts of tertiary ole?ns, such as isobutylene,
on the other hand, contain the ole?n predomi
nately as the tertiary alcohol only and exert a
' negligible ole?n vapor pressure.
The separation and recovery of secondary ole»
into a settler l where the unabsorbed hydrocar
Cl bons are removed by means of pipe 8 consisting
mainly of butane.
?ns from strong sulfuric extracts is accomplished
The sulfuric acid extract is
removed from the settler 1 by means of pipe 9
by the counter-current action of a saturated hy
drocarbon gas having at least 20° C. difference in
and passed to the upper part of the liquid ex
traction tower ill. In the lower part of the liquid
the boiling point from the secondary ole?ns such 10 extraction tower Ill is passed a liquid para?‘inic
as propane or by extracting the ole?ns from the
hydrocarbon solvent, such as pentane, by means
strong ole?n-sulfuric acid extract by the counter
of pipe ll, which passes in countercurrent flow
current action of an inert liquid solvent such as
to the sulfuric acid in the tower. The sulfuric
pentane or hexane. It has been found that an
acid, with most of the ole?ns removed, is then
extract of 83% sulfuric acid containing 1 mol of
recycled by means of pipe l2 to the reactor l.
ole?n per mol of sulfuric acid at 30° C. is in
The liquid pentane with the ole?n solution is
equilibrium with a liquid naphtha containing 11%
removed from the extraction tower by means of
normal butene, while a similar extract contain
pipe l3 and passed to a fractionating tower M
ing 0.2 mol of ole?n per mol of sulfuric acid is
in equilibrium with a naptha containing 1.2%
normal butene. Therefore the corresponding ole- _
where the secondary ole?ns are distilled over to
pipe 15 and the liquid paraf?nic hydrocarbon sol
vent is removed by means of pipe I l and recycled
to extraction tower ill. The fractionating tower
?n vapor pressures of these two extracts are cal
culated to be 4.2 and 0.46 lb. per square inch,
i4 is provided with a condenser I? at the upper
respectively. Therefore an 83% sulfuric acid ex
part and a heating coil [8 at the lower part.
tract containing 1 mol of the ole?n per mol of 25
I claim:
the sulfuric acid can be stripped at 30° C. and at
1. Improvements in the separation and concen
atmospheric pressure by passing it down a tower
tration of a secondary ole?n from a hydrocarbon
oountercurrently through a stream of gaseous
mixture containing the said secondary ole?n
propane and the gas leaving the top of the tower
which comprises contacting a hydrocarbon mix
should contain approximately 25% normal butene
ture containing a secondary ole?n with sulfuric
and 75% propane.
The butene is then recov
acid of about 75%—°0% concentration, thereby
ered by fractionation and the propane recycled.
tion equipment.
forming a solution of the secondary ole?n in said
acid, extracting the secondary ole?n from said
acid solution by means of a saturated hydrocar
bon compound, the said saturated hydrocarbon
compound having at least 20° C. difference in
Alternately, a strong extract is treated counter
currently with liquid pentane and the liquid pen
tane leaving at the top of the extraction tower
of dissolving the secondary ole?n and separable
from the said secondary ole?n by fractionation.
The extract leaving the bottom of the tower con
tains only 0.2 mol of ole?n per mol of sulfuric
acid and is recycled directly to the ole?n absorp
contains approximately 10% normal butene.
boiling point from the secondary ole?n, capable
The 40
butene is recovered by fractionation and the pen
tane recycled to the extraction tower. When
some alkyl sulfate or alcohol is carried over
mechanically or otherwise by the pentane, it is
readily separated as bottoms in the fractionating
tower and is recycled to the extraction step along
with the pentane. The lean acid extract from
the extraction tower is recycled directly to the
ole?n absorption equipment.
The stripping or the extraction process requires
a suitable length of time as the reversion of al
2. Improvements in the separation and concen
tration of a secondary ole?n from a hydrocarbon
mixture containing the said secondary ole?n
which comprises contacting a hydrocarbon mix
ture containing a secondary ole?n with sulfuric
“ acid of about 75%-90% concentration, thereby
forming a solution of the secondary ole?n in said
acid, extracting the secondary ole?n from said
acid solution by means of a saturated hydro
carbon compound in the liquid phase, the said
saturated hydrocarbon compound having at least
20° (Indifference in boiling point from the sec
cohol or alkyl sulfate to ole?ns is relatively slow.
Since more time is generally allowed in extrac
ondary ole?n, capable of dissolving the secondary
tion equipment than in stripping equipment, there
ole?n by fractionation.
ole?n and separable from the said secondary
are certain mechanical advantages in recovering
3. Improvements in the separation and concen
the ole?n by extraction. The extraction or strip
tration of a secondary ole?n from a hydrocar
ping operation may be carried out at substan
bon mixture containing the said secondary ole?n
tially atmospheric pressure and at temperatures
which comprises contacting a hydrocarbon mix
below that at which substantial polymerization
ture containing a secondary ole?n with sulfuric
of the ole?ns in the acid extract will take place,
acid of about '75%—90% concentration, thereby
probably from 0 to 60° C.
forming a solution of the secondary ole?n in said
The invention will be more clearly understood
acid, extracting the secondary ole?n from said
on reading the following description with refer
acid solution by means of a saturated hydrocar
ence to the accompanying drawing.
bon compound in the vapor phase, the said sat~
Numeral 1 designates the reactor into which is 65 urated hydrocarbon compound having at least
passed, at the upper part, sulfuric acid of about
20° C. difference in boiling point from the sec
83% concentration by means of pipe 2, and a
ondary ole?n, capable of dissolving the secondary
mixture of hydrocarbons having four carbon
ole?n and separable from the said secondary
atoms to the molecule and containing both butane
’ ole?n by fractionation.
and a secondary ole?n is passed by means of pipe 70
3 into a lower part of the reactor. 'An agitator
HAROLD W. SCHEELINE.
Документ
Категория
Без категории
Просмотров
0
Размер файла
348 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа