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Patented Oct. 29, 1946
‘ George R. Bond, JrQ, Paulsboro, N. J., assignor to
Houdry Process Corporation, Wilmington, Del,
a corporation of Delaware
‘N0 Drawing. Application March 31, 1944,
Serial No. 528,949
4 Claims. (01. 2.605669)
The present invention relates to improved
methods for the puri?cation of styrene and its
homologues produced in the cracking of high
boiling hydrocarbon
I-Ieretofore the commercial preparation of com
pounds having a. styrene nucleus has been in
accordance with the classical methods, such as
molecular dehydration of betaJ-phenyl ethyl alco
hol. Recently dehydrogenation methods have
been employed such as the dehydrogenation of
ethyl benzene and iso-propyl benzene for the
tages of‘ the‘present invention will be apparent
as the description proceeds. '
‘ ‘
In‘ accordance with the preferred form of the
present invention a cut of a cracked hydrocarbon
oil containing'a styrene type ‘compound is‘puri
?ed o‘f‘fthe reactive materials by effecting reac- .
tion of theimpur‘ities in ‘the presence of sulphur
dioxide and by separating the high boiling'reac—‘
; tion ‘products from the cut. ‘
The cracked hydrocarbon, which is preferably
a narrow cut relatively rich innstyrene‘ or in a
homologue of styrene, is treated with sulphur di-‘
oxide;' ‘The cut may conveniently be saturated‘
spectively. The puri?cation of the dehydrogena
with sulphur dioxide by bubbling the gas through‘
tion product of these processes is relatively sim
the out, though obviously liquid phase sulphur‘
ple and involves the fractionation of the product
dioxide may be added to the cut‘in limited amount
to separate the ‘unsaturate from the saturate.
insufficient to leave any liquid phase sulphur ‘di- ,
It has heretofore been known in the arttthat‘
oxide undissolved in the. cut. ‘The cut contain
compounds having a‘styrene nucleus, by which it
ing dissolved sulphur dioxide is maintained at a
is intended to include. styreneand its homologues,
are obtained both in thermal and catalytic crack 20 temperature below about 130° F. for. at least 15
minutes; No catalyst is needed to effect the reac:
ing of gas oils. The percentage of such materials
tion and it is preferred )not‘to employ any’ inas
produced depends in both thermal and catalytic
much as catalysts will generally promote reaction
cracking to a substantial extent upon the condi
. of the‘ sulphur dioxide ‘with ‘styrene type ‘come
tionsof cracking, particularly upon the tempera
ture, higher temperatures being conducive to 25 pounds. Temperatures substantially below room
temperature are not desirable since'the rate of .'
higher yields of styrene and its homologues.
reaction is reduced. Operation at such tempera
Various methods have been proposed for the puri
production of styrene and tic-methyl styrene, re
tures though is within the scope of this invention.
The sulphur dioxide treatment causes the for
eral involve fractionation, and concentration by ,
30 mation of a tarrymaterial without anysubstantial
solvent extraction.
loss of either the styrene'materials or the prin
I have found that cuts of cracked hydrocarbon
cipal ole?ns present. It is not known de?nitely
oils containing styrenes also contain small per
what the impurities are which are removed or
centages of reactive materials which interfere
what the tarry material is, whether a polymer of
with the customary uses of styrene. These ma-v
the highly reactive ole?ns or a product of inter
terials also interfere with some of the purifica
action of the sulphur dioxide with the highlyreac
tion methods employed and in many instances
tive impurities. It is to be noted that under the
with the production of styrene derivatives. In
?cation of the styrenes so produced and in gen
general, these reactive materials can not readily
be separated from the styrene by known puri?
conditions of treatment‘ole?ns generally do not
react to any substantial extent with sulphur‘
cation methods, but remain with the styrene, this 40
Following the sulphur dioxide treatment the
being true both in conjunction with fractionation
tarry material formed from the reactive compo-f
and solvent extraction. An example'of the inter
nents is removed from the unreacted materials.
ference of these reactive materials with styrene
Likewise it is desirable to remove unreacted sul
is found in the preparation of nitrosites of the
phur dioxide. Convenient methods for the re
styrene. When nitric oxide is reacted with the
moval of these two are to distill the cut, prefer
styrene compounds in the hydrpcarbon oil the
ably with steam, whereby the tarry material is
product which. is produced is of a dark gummy
consistency instead of being in the form of the
separated, and to wash the wt either before or'
after steam distillation with an alkaline wash
characteristic light yellow crystals.
50 such as a solution of caustic soda.
to provide methods for the puri?cation of styrene
When it is desired to separate the styrene from
a cracked gasoline the sulphur dioxide treat
. compounds produced by cracking of hydrocarbon
oils and to free the styrene compounds of highly
ment may be effected either before or after mak
ing a narrow cut of the'gasoline, which cut con
Among the objects of the present invention are
reactive impurities.
Other objects and advan
56 tains the desired styrene components.
In ‘the
case of styrene itself the~cut will ordinarily con
tain styrene, ethyl benzene, xylene, and the paraf
?ns, naphthenes and less reactive ole?ns which
boil in substantially the styrene range. By sol
vent extraction the para?ins and naphthenes may
below 130° F. for at least 15 minutes in the ab
sence of undissolved liquid phase sulphur diox
ide, whereby reactive impurities are caused to re
~-act to form a high boiling reaction product and
:separating the reaction product and excess sul
be separated so that the fraction contains sty- 7 V phur dioxide from the hydrocarbon oil.
mm, ethyl benzene,xylene and‘ the less reactive
2. The process of purifying a crudestyrene
ole?ns. By close fractionation it is possible to
compound produced by the cracking of a higher
obtain a relatively pure styrene. The sulphur
boiling hydrocarbon oil resulting in the com
dioxide treatment may be employed at any stage 10 pound containing reactive impurities, which com
in the preparation, though it is preferred to treat
prises dissolving sulphur dioxide in the com
the relatively narrow out prior to solvent extrac
pound, maintaining sulphur dioxide dissolved in
said compound for a period of at least 15 min
A 120° to 150° C. cut of a naphtha obtained by
utes at a temperature below about 130° F. in the
thermal cracking of gas oil was saturated with
absence of undissolved liquid phase sulfur diox
sulphur dioxide by bubbling the sulphur dioxide
ide, whereby the reactive impurities are caused
through the cut at room temperature. The cut
to react to form a high boiling reaction product,
so saturated was allowed to stand for one ‘hour
and separating the reaction product from the
at room temperature. It was then washed with
caustic solution to remove free sulphur dioxide 20
3. The process of purifying cracked naphtha
and ‘steam distilled. ,A dark red gummy residue
was vleft following the distillation. A sample of
the cut prior to S02 treatment ‘was saturated
with nitrogen trioxide at roomtemperaturet0
of highly reactive impurities which comprises
dissolving sulphur dioxide in'the naphtha, main
taining the naphtha together with dissolved sul
phur dioxide at a temperature ‘below about 130°
form‘ the nitrosite of the styrene. vThis produced‘ 25 F. for at least about 15 minutes in‘ the absence
a nitrosite which was a dark’ reddish brown oily’v
of liquid ‘phase sulphur dioxide and in the 'ab
precipitate] The yieldoflnitrosit'e' after alcohol
sence of a catalyst whereby the reactive impuri
puri?cation ‘showed the naphtha ‘contained 25.5%
ties ‘are caused to react to form alhigh boiling'
styrene. Following SOzpuri?c'ation of the origi
reaction product, and separating the reaction
nal cut a nitrosite was formed by the same meth
od; which nitrosite was a relatively pure, pale
yellow crystalline precipitate which was easily
30 product from the] naphtha by distillation.
‘ 4. The method of purifying a hydrocarbon oil
containing a styrene compound, which hydrocar
?ltered. ' The yield of nitrosite showed that the
bon oil was produced by cracking a gas oil,,which
naphtha‘ after treatment contained 25.1% sty
comprises dissolving sulphur dioxide in the hydro;
rene. .The difference .in the indicated styrene 35 carbon oil, maintaining the oil with the sulphur
content was probablydue to the. difficulty of puri
dioxidedissolved therein “at a temperature below
?ca'tio'n of the oily nitrosite.
130° F. for at least 15’ minutesin the absence of
What ,Ilclaim is:
. '
.1. The method of purifying a hydrocarbon oil’
containinga styrene compound, which hydrocar
bonoiliwas produced by cracking a gas oil, which
comprises dissolving sulphur dioxide in the hy
drocarbon oil, maintaining the oil with the sul
phur dioxide ‘dissolved therein at a temperature
liquid phase sulphur dioxide undissolved in the
oil,'whereby reactive impurities are caused to re-'
40 act to form a high boiling reaction product and
separating the reaction product and excess sul
phur dioxide from the hydrocarbon oil.
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