close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2407862

код для вставки
Patented Sept. 17, 1946
2,407,861
UNITED STATES PATENT 0F ICE
2,407,861
‘
PROCESS OF TREATING HYDROCARBONS
I. Louis Wolk, Bartlesville, 0kla., assignor to '
Phillips Petroleum Company, a corporation‘ of
Delaware
No Drawing. ApplicatioIn September 5, 1942,
Serial No. 457,471
1
2 Claims.
(Cl. 202-57)
The present invention relates to the stabiliza
tion of polymerizable organic compounds against
giving rise to the numerous operating di?lculties.
polymerization and oxidation during concentra
The loss of even very small amounts of unsatu
tion and puri?cation and to stabilizers capable
rates through oxidation or polymerization may
of preventing the polymerization and deteriora
tion of the polymerizable compounds.
Among the most important monomers used at
the present time in the manufacture of synthetic
are theunsaturated hydrocarbons: bu
tenes, butadiene 1.3, piperylene, and their de
rivatives. Acrylonitrile, styrene, methyl aciylate,
and other polymerizable organic compounds may
be copolymerized with the unsaturated hydro
carbons to yield various rubber-like polymers
having characteristic properties. The polymeri
‘
An object of the present invention is to elimi
nate oxidation and polymerization of polymer
zable unsaturated organic compounds‘ during
their concentration and‘ puri?cation by distilla~
tion.
zation is advantageously carried out in an emul
‘
undesirable reactions.
For emulsion polymerization the mono
A further object of the
Solvent treatment, distillation, or both, may be.20 the prevention of losses of unsaturated com~
employed in the puri?cation and concentration
of the monomers. While distillation is in many
cases preferred as the operation by which the
sition of polymeric
tion products on the apparatus during distilla
tion.
'
‘Another object of the present invention is to
provide an effective and desirable method for the
distillation of polymerizable organic compounds.
Still another object is to provide suitable sta~
bilizers capable of inhibiting vapor phase poly
30 merization and/or oxidation during the distilla
tion of polymerizable organic compounds.
instances of record in
The present invention effectively prevents the
bilizers are added to protect against deteriora~
tion. Most of these stabilizers interfere with the 35
pollmerization and must be removed prior to the
in the liquid phase in
to concentrate near the bottom of the fractiona
polymerizationprocess, Stabilizers of high boil
ing point are most often used because they may
be separated from the monomer by distillation
tor. In some instances, fractionators may be
' prior to the polymerization procedure. Polymer 40 constructed of or contain certain metals or other
I formation and decomposition of the monomer,
materials which inhibit polymerization. Both
‘chie?y by oxidation, are apt to take place in
the high boiling inhibitor and the contact in
hibitor are inelfective for inhibition of the oxi
dation and/or polymerization of the monomer in
the vapor phase. I have observed that consid
erable polymer formation does occur in distilla
tion of monomers which contain'non-volatile or
the equipment used for separation of the sta
bilizer from the monomer. In the steam distilla
tion of styrene, for example, for separation from
the stabilizer prior to use in polymerization, con
siderable trouble with polymer formation is en
countered.
In the conventional fractionating systems, the
high boiling inhibitors. Since these inhibitors
50 are effective for the stabilization of the liquid
inclusion or introduction of atmospheric or other
'oxygen in the equipment results in or favors
oxidation and polymerization of these unsatu
rated organic compounds with the attendant
monomers in transfer and storage, polymeriza
tion in the vapor phase must take place during
the fractionation.
present invention. pre
losses in yield and deposition of polymers in the 55
apparatus and system. The conjugated diole?ns
are especially likely to undergo such reactions
and hence, are especially troublesome. This con
dition obviously is undesirable and results in
substantial losses of the monomers as well as 60
The present invention is performed by adding
2,407,861
3
_
4
portance in the manufacture of synthetic rubber
include:
to the monomer an inhibitor having a suitable
boiling point and solubility for incorporation in
the liquid material to be purified or in the water
if steam distillation is employed in the puri?ca
Compound
Boiling point
tion. The selection of a suitable stabilizer is de
‘' 0.
pendent upon the particular monomer to be in
hibited thereby. Preferably the inhibitor or sta
bilizer has approximately the same boiling point
Vinyl chlorido_‘___.,__....__...._
7
Chloroprcne ............. . _
59
139
2,3-dimethyl butadiene- ,
70
157
Acrylonitrilc .... _ .
as the monomer so_as to prevent oxidation and
78
Methyl acrylutc. .
10
polymerization during all the process steps pre
ceding the polymerization step in which it is co
polymerized with another monomer to form syn
Styrene . _ _ _ . . . _
. _ . . _ . _ . _ . _ . . . _ . _ . _ .
. _.
amines are preferred, since the amines may be
tolerated in minor proportions in the polymer
ization step and in the resulting product. For
the purpose of illustration, the boiling points of
some of the aliphatic amines are listed below:
Compound
Boiling point.
° 0.
Methylamine.......................... ..
Trimethylamme _ . .
with a conventional inhibitor. The stabilizer
Dimetbylaminc.
may be removed prior to the polymerization step 25 Ethylsmine.____.
Isopropylammer
as disclosed hereinafter or may in some instances
Methylethylamlne
be allowed to remain in the monomer since some
v
95
Amylamine____
distillation. For example, separations sometimes
an entrainer to aid in the fractionation. The in
183
203
210
255
264
130
146
140
266
295
155
311
_. ._.
156
N dihutylamine-..
284
313
159
318
Sec.-octylamine ____ __
164
327
Methyl heptylamine.
165
329
From a comparison of the boiling points it will
be apparent that methylamine, trimethylamine,
and dimethylamine are suitable for use in a mix
ture of C4 hydrocarbons, while the ethylamine,
isopropylamine, and methylethylamine are suit
able for use with the C5 hydrocarbons. Ethyl
propylisobutylamine is especially suited for use
with styrene since the boiling points are substan
tially identical. For inhibition of the higher‘
ing styrene, however, it is preferable to use a
60 mixture of acid soluble aliphatic amines boiling
—7
l9
-6
21
——5
23
1
34
4
39
26
79
86
ne-l _______ -_
30
2-methyl butane-1.
31
88
Isoprene. -.._
34
93
Pentene-2___.
36
97
2-methyl bute
Cyclopentadiene
..... -.
38
41
100
106
Piperylene . . . . . _
. . . _ _ _ _ -_
43
109
44
111
within the range of temperatures encountered
in the distillation of the organic compounds.
Such a mixture offers full protection against de
terioration during distillation since the compo
65 nents are distributed through both the liquid
phase and the vapor phase in the fractionator.
The inhibitor passing overhead in the fraction
ator is condensed with the condensate and‘may
be removed from the monomer by contact with
w
Of these, isobutene, butadiene, isoprene, and
p'iperylene are the most important in the man
an aqueous acid solution. The removal is readily ‘
accomplished by intimately contacting the mon—
omer with the aqueous acid solution and separat
ing the puri?ed monomer from the resulting
mixture.
‘
95
104
Methylamylamine.
Ethylpropylisobutylamine
45 Tripropylamine-_._
° F.
Butene-l ______ __
ufacture of synthetic rubber.
1114
196
196
198
boiling polymerizable organic compounds includ
Isobutene _________________________ ..
Cyclopentene ................................... _.
90
91
91
92
230
Boiling point
_____ ..
174
' 180
129
points as follows:
Pen
.
84
Hexylamine ...... _.
carbon atoms respectively and having boiling
. _ . . . . . ..
169
171
171
154
124
Among the ole?ns and diole?ns are the members
of these series having four carbon atoms and ?ve
1,4-pentadiene _ _ _ _ . _ _ .
147
76
77
77
68
110
invention.
My invention is applicable to the ole?ns, diole- ,
?ns, styrene, acrylonitrile, and other polymeriz
able and/or oxidizable unsaturated compounds.
..... __
145
64
Isohexylamine_._
Heptylamine _______________ _.
>
The invention will be more readily understood
by reference to the following examples which are
illustrative of the process-of my invention and
of compounds suitable for use in carrying out my
ilin
> 145
63
82
..... ..
Dnsobntylamine _ __
vention is also applicable to separation by the
Butane-2 (low bo1hng)_ _
56
63
_____
40 Dipropylamine ___________ _.
involve the formation of an azeotrope or use of
93
1 1'1
120
133
___________ __
......... _.
of the monomers by methods other than by simple
Butene-2 (high
63
45
49
may be employed equally ad
vantageously in the segregation and puri?cation
Butadiene-L3 _________ _.
17
79
merization step without adversely affecting the
° C’.
45
35
The aliphatic amines, particularly the tertiary
Hydrocarbon
39
7
34
........ ._
aliphatic amines, the mercaptans, and the alkyl
sul?des may, for example, be allowed to remain
in the monomers charged to the emulsion poly
19
4'
_
Tert.-butylamine ............... . _
.
° F.
-7
........ ..
..... ._
of the stabilizers, althou h effective in preventing
deterioration of the monomer, do not appreci
use of selective solvents.
177
205
in the present invention, the aliphatic alkyl
part higher boiling than the compound inhibited
or I may use a volatile inhibitor in conjunction
polymerization.
The inhibitors
173
80
146
Of the stabilizers or inhibitors suitable for use
thetic rubber latex. One addition of such a stabi
lizer is usually sufiicient since the stabilizer re
mains in admixture with the monomer through all
.the process steps. In any event, at least part of
the inhibitor exists in the vapor phase during dis
tillation. The boiling point of the inhibitor may
be such that it is entirely gaseous at the temper
ature and pressure of the distillation. I may use 20
a mixture of the inhibitors, part lower boiling and
ably retard copolymerization.
° F.
-—14
Other polymerizable organic materials. of im
75
-
I
The mercaptans may also be used as inhibitors
2,407,861
in accordance with the present invention. The
hydrazines enumerated may be used as inhibi
boiling points of some of the mercaptans suitable
for use are as follows:
Compound
Boiling point
“.__\_\__
_____
° 0. 6
Methyl mcrcaptan ______ _ .
Ethyl mercaplnn ........ _ ,
97
59
67
...... . _
1348
152 10
88
190
N. butyl mercaptam-
98
20%
N. amyl mercaptan. .
Isoamy] mcrcaptan__
125
130
257
266
149
300
_
N. hexyl mercaptan __; _______________ __
pounds with which they are used as inhibitors. ,
° 1'‘. 43
3t
Isopropyl mercaptan.
N. propyl mercaptau____
Isobutyl morcaptan. .
tors for styrene since they all will be vaporized
at temperatures below those at which the styrene
5 is vaporized. The alkyl hydrazines are powerful
reducing agents and are especially e?ective‘ in
preventing oxidation of the unsaturated com
_
Like the aliphatic amines, the dimethyl hydra
zines may be removed from the hydrocarbons by
contact with an aqueous acid solution.
Other inhibitors which may be used in my proc
ess include ammonia, B. P. —33° 0., and hydrogen
sul?de, B. F. —60° C. The normally gaseous
compounds may be used as inhibitors in the va
Methyl and ethyl mercaptans are suitable for 15 por phase during the distillation of the polymer
use in a mixture of C5 hydrocarbons, ethyl mer
izable compounds by dissolving in small propor
captan having thesame boiling point as Dentene
tions in the compounds or by addition directly
2. Isopropyl mercaptan has substantially the
‘to the still whereby the gases are admixed with
same boiling point as isoprene. N. propyl mer
captan, as well as the lower boiling mercaptanes, '
may be used as inhibitor for 2,3 dimethyl bu
and follow the volatile vapors from the still
through the fractionation steps. The ammonia
may be removed by a water wash, while the hy
tadiene-1, ,
drogen sul?de is preferably removed by contact
with aqueous alkaline solution.
The following examples illustrate more clearly
the application of the present invention and are
not to be construed as limiting the invention in _
any way
captans are readily removed from the polymer
izable organic liquid prior to the polymerization
step by contact with an aqueous alkaline solu
tion.
The alkali wash serves to remove organic '
peroxides as well as the mercaptans. Traces of
alkali in the monomer are not objectionable in
emulsion polymerization.
Example I
A mixture containing 50% butadiene along
with a substantial proportion of butenes-2 as im
purities is fed to a distillation system comprising
.
a packed column operated at about 75 pounds per
The alkyl sul?des may be used in my process.
square inch absolute and with a kettle tempera
Those having suitable boiling points are:
""
ture of about 113° F. Butadiene of about 98%
purity is taken overhead and butene removed
Compound
N
Methyl
from the bottom. Phenyl-beta-naphthylamine
Boiling point
about .05% by weight, is used asinhibitor. After
operating 48 hours, the distillation system was
torn down and cleaned out because the system
was so plugged that operation was impossible.
i
A large amount of pasty material was found in
the still. The column was stopped by a solid
white crystalline deposit. The ?rst pass of the
condenser ‘was packed with a mixture of the
white deposit and Raschig rings which had car
.
Methyl sul?de may be used as inhibitor in
the distillation of the C5 hydrocarbons and chlo
roprene or higher boiling polymerizable com
pounds. Methylethyl sul?de is especially suit
able as inhibitor for 2,3-dimethyl butadiene,1,3
and may be used with acrylonitrile or methyl
acrylate. N. propyl sul?de is especially suitable
for use with styrene, although the lower boiling
sul?des may also be used for inhibition of poly
ried over as the result of the formation of the
butadiene complex.
50
The above described system was cleaned out
and distillation of butadiene continued with the
use of .5% methylamine and .05% phenyl-beta
naphthylamine as inhibitors. After 48 hours the
distillation system was operating satisfactorily.
The methylamine was removed from the buta
diene by an aqueous acid treatment. About 1%
‘ to the polymerization
step by contacting the
monomer with a mercuric or cupric salt with
hydrogen sul?de was substituted for methyl
amine, being added continuously to the base of
the fractionator, and the distillation continued
24 hours. The hydrogen sul?de was removed by
which the sul?des form addition products.
Another series of compounds suitable for use 60 contact with an aqueous alkaline solution. The
in my process are the lower boiling alkyl hy
distillation was then continued 24 hours using
drazines.
small amounts of ammonia, about 1% by weight,
instead of the hydrogen sul?de, continuously in
Compound
troduced to the system with the feed.
Boiling point 65
Dimethylhydrazine (1111s.) _______ __
Dimethylhydrazine (sym.) ______ __
Methylhydrazine ________ ._
Diethylhydrazine _____________ _.
Ethylhydrazine _______________________________ __
The dimethyl hydrazines may be used as in
hibitors with 2,3-dimethyl butadiene-1,3, acrylo
The dis
tillation was shut down at the end of four days.
A small amount of pasty material was found in
the still. The column was not disassembled since
the pressure drop through the column had not
appreciably increased from the beginning of the
trial runs.
Example II
E?iuent from the catalytic dehydrogenation of
nitrile, and methyl acrylate. Any of the alkyl 75 ethylbenzene containing 2‘3.5 weight per cent
styrene inhibited with .1% tertiary butyl cate
2,407,861
Example V
A mixture containing 50% butadiene along with
chol was fractionated in a fractionator contain
ing the equivalent of 100 theoretical plates. The
a substantial proportion of butenes as impurities
is fed to the center of a sixty plate bubble cap
column and 95% acetone is supplied to the top
of the column in quantities ten times the weight
of the feed. Hydrogen sul?de is introduced near
benzene, together with small amounts of benzene
the bottom of the column and passes overhead
and toluene were taken overhead as vapors.
substantially unabsorbed by the acetone. The
Polymer was removed from the kettle in propor
tions such that an appreciable loss of styrene was 10 liquid flowing from the bottom of the column is
heated to boil out the puri?ed butadiene and is.
represented. Ammonia, hydrogen sul?de, ali
recirculated, while a portion of the butadiene
phatic amines, alkyl hydrazines, alkyl sul?des,
vapor is returned to the bottom of the column to
. and mercaptans were successively introduced to
maintain the'saturation of the descending sol
the base of the fractionator with the result that
vent.
The remainder of the butadiene recovered
the polymer formation was greatly decreased.
from the solvent is condensed and removed as the
Example III
I_
product. In this manner the butadiene is easily
enriched to 95% concentration.- On inspection
In the steam distillation of styrene for puri
of the apparatus, substantially no gum polymer
?cation and removal of high boiling inhibitor
the still or pot and the associated fractionating 20 is detected. This is apparently due to the incor
poration of the inhibitor, since a similar run
column ?lled with Raschig rings was heated to
under ordinary conditions without inhibitor re
100° C. with live steam. Styrene inhibited with
sults in noticeable gum or polymer formation,
phenyl-beta-naphthylamine was charged to the
particularly after continued operation.
still in 40 pound batches as it distilled so that
no more than 5 gallons of styrene was in the pot 25
Example VI
at any time. The distillation with steam con
The butadiene-containing mixture of the fore
tinued for two hours and forty-?ve minutes, dur
going example is contacted in the apparatus of
ing which time 200 pounds of styrene was charged
fractionator was operated at 'a pressure of 16
pounds per square inch absolute. Styrene of
99% purity was withdrawn from a point in the
lower section of the fractionator while ethyl
Of this amount 180.5 pounds of
the foregoing example with nitrobenzene at 10 to
during the distillation. Polystyrene was carried
mixture is regulated so that substantially no
butadiene is present in gases escaping at the top
to the still.
styrene was recovered, representing a loss of 9.8% 30. 20° C. The rate of feed of the solvent and gas
into and deposited in the column. The distilla
of the tower. The butadiene recovered from the
tion was continued an additional 4 hours during
solvent accumulating at the bottom by distillation
which 162 pounds of styrene was charged to the
still. The distillation was considerably slower 35 as in Example V is of high purity, being in the
neighborhood of 95% pure. Ammonia is used as
than previously due to polymer deposition in the
inhibitor. As in Example V, no appreciable poly
column. The loss at the slower distillation rate
mer formation takes place.
was somewhat less, being about 2.5%. Following
I claim:
‘
'
this distillation the still had to be shut down for
1. In the fractional distillation of a liquid poly
cleaning. The perforated plate supporting the 40 merizable
organic compound in a fractionation
Raschig rings was found to be nearly completely
zone wherein said compound is subjected to con
plugged with polymer. -
_
Styrene, inhibited by the addition of mixed
aliphatic amines boiling within the range of 290
ditions favorable to oxidation of said compound,
the improvement which comprises introducing
300° F., was distilled in the apparatus. ‘In six 45
hours operation 400 pounds of styrene was
charged to the still. The loss due to polymer
formation was reduced to less than 1%.
Example IV
50
A C4 fraction containing butadiene admixed
with butylenes, isobutylene and butane was passed
into countercurrent contact with furfural con
taining 5% water in a plate-type absorption col
umn/ The column was operated, 'at 65 pounds 55
per square inch absolute with a top temperature
of 120° F. and a bottom temperature of 240° F.
The C4 fraction contained .02% phenyl-beta
naphthylamine inhibitor. In a few hours the
into said fractionation zone an oxidation inhibi
tor substantially non-volatile under conditions of
distillation in an amount sui?cient to inhibit oxi
dation and polymerization of said compound in
the liquid stateI and continuously introducing
into said fractionation zone a second oxidation
inhibitor more volatile than said organic com
pound in an amount sufficient to inhibit oxidation
and polymerization of said compound in the vapor
state.
2. In the fractional distillation of a liquid poly
merizable organic compound in a fractionation
zone wherein said compound is subjected to con
ditions favorable to oxidation of said compound,
the improvement which comprises introducing
system was shut down because of the formation 60 into said fractionation zone an oxidation inhibi- -
of polymeric material in the lower section of the
column.
Using methylamine inhibitor, together with the
phenyl-beta-naphthylamine the furfural solvent
extraction of butadiene from the C4 hydrocarbons
was successfully carried out with very little ly-'
mer formation. The methylamine was partly
absorbed in the furfural. Traces of methylamine
were removed from the purified butadiene by in- '
timate contact with an aqueous acid solution.
tor substantially non-volatile under conditions of
distillation in an amount sufficient to inhibit oxi
dation and polymerization of said compound in
the liquid state, and continuously introducing
I into the base of said fractionation zone a second
‘oxidation inhibitor more volatile than said or-'
ganic compound in an amount su?icient to inhibit
oxidation and polymerization of said compound
in the vapor state. a
I. LOUIS WOLK.
Документ
Категория
Без категории
Просмотров
0
Размер файла
647 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа