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Патент USA US2409262

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^ Patented Oct. 15, 1946
Edmond L. d’ûuville and Bernard L. Evering, Chi
cago, Ill., assignors to Standard Gil Company,
Chicago, Ill., a corporation of Indiana
Application June 24, 1943, Serial No. 492,040
13 Claims. (Cl. 260-6835)
This invention relates to the production of _iso
butane from normal butane and more particularly
relates to the isomerization of normal butane and
hydrocarbon fractions containing a large propor
termittent operation, thus precluding continuous
Another difliculty inherent in processes using
supported aluminum chloride results from the
tion thereof into products consisting substantially
continuous drop in activity due to the loss of
of isobutane in the presence of a speciñc liquid 5 catalyst from the support. Thus with constant
catalyst of the aluminum chloride type.
feed rate a constantly diminishing conversion re
The present application is a continuation-in
sults. This change in activity can be compensated
part of our copending applications, Serial No.
for by varying the activator concentration so
422,983-4, filed December 15, 1941, which in turn
that the activator concentration is lowest at the
are continuations-in-part of applications which
highest catalyst activity and highest for the mini
have now matured into Letters Patent 2,266,01l~2.
mum catalyst activity for the cycle. This is ob
_ Isobutane has in recent years assumed increased
jectionable since it does not permit the continuous
importance as a basic or starting material for the
usecf the optimum activator concentration. In
preparation of valuable hydrocarbon products, as 15 practical operation it has been found more feasi
well as in the synthesis of many chemical com
ble to allow the conversion to fluctuate between
pounds. Isobutane can be alkylated, for example,
use of the optimum activator concentration. In
With oleñns such as propylene, butylene, or other
low boiling unsaturated hydrocarbons, or it can
predetermined limits giving an average conver
over catalysts such as chromic oxide gel or mag
ride has an appreciable solubility in liquid butane,
operation With supported catalysts is restricted to
vapor phase operation. Again'since the isomeri
sion measurably below the potential conversion
be dehydrogenated to isobutylene thermally or 20 of the given equipment. Since aluminum chlo
nesium chromite and the isobutylene polymerized
by known means to resins, lubricating oils, or
dîisobutylene. The latter compound is easily
converted to so-called isooctane by hydrogenation 25
and forms a convenient source of this valuable
product for use as premium or aviation fuels.
The conversion of normal butane to isobutane
has been investigated to a considerable extent and
many »processes have been proposed using alumi
num chloride as the catalyst. These processes al
though adopted commercially are subject to many
operational diñiculties which make them rela
tively inefficient. In addition the complicated
equipment required results in unusually high in
stallation costs.
Prominent among these proc
esses are those which make use of supported
zation reaction is exothermic and since supported
catalyst makes use of ceramic and clay type Sup
ports Which are notoriously poor conductors of
heat, special devices are necessary to dissipate the
heat of reaction. Finally, since solid aluminum
chloride is extremely susceptible to oleñns and
30 higher
hydrocarbons special and expensive pre- cautions are necessary to prepare a feed stock
which will not change the physical state of the
supported aluminum chloride, thus reducing the
active surface causing early depletion of the ac
35 tivity of the catalyst.
We have found that excellent yieldsof iso
butane can be obtained from normal butane with
aluminum chloride as catalyst. The principal
unusually long catalyst life by subjecting it at
diñiculty inherent in these processes results from
comparatively moderate temperatures and pres-v
the fugitive character of the catalyst. The alumi 40 sures to the action of a special liquid catalyst of`
num chloride is not retained permanently on the
the aluminum chloride complex type in the
support but on account of its appreciable vapor
presence of an activator.
pressure is carried along with the eiiluent hydro
‘It is an object of our invention to provide an
carbon vapor, Many devices have been tried to
improved process for the production of isobutane
prevent the escape of the aluminum chloride into 45 from normal butane and hydrocarbon fractions
lines Where plugging can result or into equipment
containing large proportions of normal butane.
the eil'icîency of which or even the operability of
Another object is to provide an economical
which can be seriously affected. For example,
method 4of preparing a product consisting sub
beds of clay have been placed down stream from
stantially of isobutane by the isomerization of nor
the catalyst chamber to adsorb the aluminum 50 mal butane. A further object is to provide a
chloride from the efliuent hydrocarbon.I An alter
process for the production of isobutane from nor
nate method has been to make use of alternate
mal butane in which a liquid catalyst of the alumi
layers of supported aluminum chloride and clay.
num chloride complex type is employed. It is also
Although these devices are effective they are
an object of our invention to provide a process for
but temporary expedients and as such require ín 5,5 the production of isobutane from which high
are obtained. It is an object of our invention to
tive aluminum” we mean the aluminum con
provide a truly continuous process for the conver
_tent of hydrolyzable aluminum co-mpounds;
sion of n-butane to isobutane. It is an object of
our invention to provide a process giving a high
e., this expression does
aluminum content of inactive compounds such
as oxides and hydroxides. A complex pre
and relatively constant conversion of n-butane to
isobutane. It is an object of our invention to pro
is an object of our invention to provide an iso
range of 67 to 82 large calories per gram atom
of active aluminum. By the expression “ac
yields of product per unit of catalyst consumed
vide a process wherein the optimum activator
concentration can be continuously employed. It
pared by the action of aluminum chloride and
hydrogen chloride on a light naphtha from nat
10 ural or straight-run gasoline substantially free
from aromatic and oleñnic hydrocarbons is em
inently suitable for use in the initial starting-up
merization process which will give high once
through conversion of n-butane to isobutane. It
of our process. Neither olefin complexes or aro
is an object of our invention to provide a process
matic or alkyl aromatic complexes (Gustavson
for the isomerization of n-butane which can
operate on the liquid phase. It is an object of 15 complexes) are desirable. After the process is
started it is only necessary to add make-up alu
minum halide or effect continuous or periodic re
generation to maintain the catalyst at the desired
level of activity.
preciably susceptible to deactivation by small 20 Throughout the specification and claims when
ever the terms “aluminum chloride-parañinic hy
amounts of olefin and higher hydrocarbons. Fur
drocarbon complex,” “parañinic complex,” or
ther objects, advantages and uses of our invention
similar expressions are employed they are in
will become apparent from the following detailed
tended to designate the liquid complex formed by
description read in conjunction with the drawings
which form a part of this specification and which 25 the reaction of aluminum halide with a saturated
hydrocarbon in accordance With a procedure of
show in a schematic manner systems suitable
the general type described above. We also refer
for carrying out our invention.
to our complex as containing “bound” hydro
In one of its broad aspects our invention com
carbons. This is to designate that the parañinic
prises treatingr hydrocarbon fractions containing
a large proportion of normal butane in the pres 30 hydrocarbon is joined to the aluminum halide by
chemical means and to distinguish the catalyst
ence of an aluminum chloride-hydrocarbon com
from such catalysts as those comprising a slurry
plex at a temperature of from about 120 to about
of an aluminum halide in a liquid hydrocarbon.
460° F. and at an elevated pressure, in the pres
However, since free aluminum chloride is appre
ence of an activator, with intermittent regenera
ciably soluble in aluminum chloride complex
tion of the catalyst to a mobile liquid form or
catalyst not all of the aluminum chloride is chem
with addition of makeup aluminum chloride in
our invention to provide an isomerization reactor
wherein the heat of reaction can be readily dissi
pated. Finally it is an object of our invention to
provide a process the catalyst of which is not ap
ically bound to hydrocarbon. The complex
preferably contains from about 16% to. about
40% hydrocarbons based on the total catalyst on
solution to maintain catalyst activity.
The feed stock for our process can be a rela
tively pure normal butane, but, generally speak
ing, essentially saturated hydrocarbon fractions 40 a weight percent basis.
composed predominantly of the butanes and con
taining a large proportion of normal butane are
preferred, since they are much `more readily
available. Suitable charging stocks, for exam
ple, are the butanes obtained by fractionating
the natural gasoline recovered from natural gas
or “distillate” wells by conventional methods or
the residual gas from a catalytic polymerization,
hydration or alkylation unit operated on a “plant
butane” cut, the oleñns in the cut ‘being substan 50
tially completely removed by the polymerization
If desired, the catalyst
can be fortified or maintained at desired activity
by dissolving sufficient aluminum halide in the
aluminum halide-hydrocarbon complex or in the
normal butane feed.
The solubility of aluminum chloride in butane
is approximately as follows:
Wt. percent of
A1013 dissolved
Lbs. of AlCls
per bbl. of
The butane fraction charged is
preferably substantially completely saturated,
. 3
. (i
l. 5
2. l
3. l
4. 3
ll. 3
or alkylation.
i. e. free from olefins, and it is also substantially
free from moisture.
U. (l2
The active liquid aluminum halide-hydrocar
bon complex used in accordance with our inven
tion may be prepared by the action of an alumi
num halide, such as anhydrous aluminum chlo
ride or aluminum bromide, and an activator af
fording a hydrogen halide on a substantially sat
Thus by simply controlling the amount and tem
perature of that portion of the butane charge
which is passed through a solution tank, the
60 quantity of make-up aluminum chloride may be
urated fraction containing, for example, paraffin
regulated with great precision. The aluminum
chloride-hydrocarbon catalyst exhibits great af
hydrocarbons at a temperature in the range from
about 50° F. to about 225° F. or more. Such a
tracts substantially completely dissolved alumi
ñnity for free aluminum chloride and hence ex
complex catalyst may be prepared, for example, 65 num chloride from the butane feed.
By introd
ducing the makeup at a rate within the approxi
2,300,249. Its activity may be measured by its
mate range of 0.1 to 1 pound per barrel or the
heat of hydrolysis as determined by any well
more limited range of 0.2 to 0.5 pound per barrel
known calorimetric method. Note U. S. Patent
of total butane charged, the added makeup is ef
In the case of aluminum chloride
fectively removed from the solution by the com
complexes such heats of hydrolysis are usually in
plex and is not carried from the reaction zone in
the approximate range of 60 to '75 large calories
solution in the effluent product.
per gram atom of active aluminum and in the
The above solubility data is based on substan
case of aluminum bromide complexes such heat
tially pure normal butane and fresh aluminum
in the manner described in our U. S. Patent
of hydrolysis is usually in the approximate 75
chloride. It has been found, however, that the
i. e. the tower may be about 1/¿ to 3A full of com
rate of solubility decreases in time when the
plex. The column of complex in the'tower should
_butane contains impurities due to an apparent
be at least ñve feet deep and preferably twenty
contamination of the aluminum chloride. This
to thirty feet deep or more. Since the top of the
can be compensated for easily by increasing the
column of complex is below the level at which
temperature of the butane and/or decreasing the
reaction products are withdrawn and since the
rate of flow of the butane through the aluminum
amount of make-up catalyst added and spent
chloride tanks. Also the difüculty may ‘be largely
catalyst withdrawn is quite small, the column of
remedied by passing through the tanks recycle
complex in the reaction zone is relatively sta
n-butane which has already been passed through 10 tionary. The term “relatively stationary” does
the reactors.
not mean quiescent because there will of course
The drawings which form a, part of this speci
ñcation are illustrative of two types of systems
according to the present invention.
Figure 1 is a ilow sheet of a system for carrying 15
out the invention by adding make-up aluminum
halide in complex; and
l‘ce a certain amount of turbulence within the
column itself. The term “relatively stationary”
means‘rather that the catalyst column is rela
tively nxed or stationary with regard to charging
stock flow as distinguished from concurrent and
countercurrent'i'low respectively.
Figure 2 is a ñow sheet of a system for prac
The isomerization reaction is carried out at
ticing the invention by adding make~up alumi
temperatures within the range from about 120°
num halide in at least a part of the entering 20 F. to about 400° F., preferably about 212° F.
butane stream.
Heat can be supplied by passing the butane and
Referring now to Figure 1, a n--butane feed
hydrogen chloride solution through a heater 2|
' stock of the type described above enters mixing
tank I0 through line || under pressure imposed
by the aid of pump I2. An activator such as an
hydrogen halide or a compound añording an
hydrogen halide under the reaction »conditions
enters mixing tank ID through line I3 and pump
in line I5 and/or by the use of a heating jacket
or other heating means 22 about section I9 of
isomerizer I8, any suitable heating medium en
tering through line 23 and being discharged
through line 24. Only the lower part of the
tower need be jacketed for temperature control,
I4. As an activator we prefer to employ an hy
and the whole tower covered by eiîective insulat
drogen halide such as ‘the chloride or `bromide 30 .ing material, or the heating jacket can extend
although we may use materials which yield hy
about the enlarged section as well as the narrow
drogen halide during the reaction.Y
section. depending upon whether it is deemed
Wherever the term “activator affording an hy
preferable to maintain the entire reactor at ap
drogen halide” or a similar expression is used
proximately the same temperature or to have the
throughout the specification and claims, it is in
two sections at diiîerent temperatures. Catalyst
tended to include not only such substances as
is added through line 25 and line 26 having valve
27 therein to the upper portion of tower I9 while
the reactants enter near the base of this tower
alkyl halides, organic' chlorides and chlorine, but
also the hydrogen halides themselves. For the
sake of simplicity the process will be described
relative to the use of hydrogen chloride, our pre
through a spraying means 28er other means for
40 dispersing the reactants through and in intimate
ferred activator. In mixing tank I0 the normal
Contact with the liquid catalyst if it appears
butano feed is partially saturated with hydrogen
chloride or other activator until the concentra
In order to maintain the activity of the alumi
tion of hydrogen halide, based on the total feed,
num halide-paralîinic hydrocarbon complex, the
lies between about 0.1% and about 20% or pref 45. complex can, if desired, be by-passed from line 25
erably between about 3% and 6% by weight'.
through line |22 and heater |23 to a tower I 24
The butane and hydrogen chloride in liquid phase
containing beds of solid aluminum chloride.
are then pumped through line I5 and line IB
Valve |25 in line |22 is open and valve |2t` in line
having valve Il therein to isomerizer I8. Al
25 is closed. In heater |23 the complex is heated
though our process can operate in either the 50 to such a, temperature that just suflicient alumi
vapor or liquid phase, the reaction is preferably
num chloride is dissolved to maintain the catalyst
carried out with the reactants in the liquid phase,
at the desired activity and the complex is allowed
and the pressure can lie within the range from
to flow over or otherwise contact the solid alu
about 100 to about 2000 pounds per square inch,
minum chloride in tower |24. Fresh aluminum
depending to a large extent upon the tempera 55 chloride can be added to tower |24 via line |21.
ture at which the reactor is maintained. A pre
The fortiñed complex then passes from tower |24
ferred pressure will be in the general vicinity of
through line §23 to line 25 at a point beyond
about 500 pounds per square inch, i. e. about 300
valve |20.
to 600 pounds per square inch.
The fortiiìcation of the complex may be con
Isomerizer I8 can ybe a reactor in the form of 60 trolled by means of valve |25, heater |23 and the
an elongated tower I 9 topped by a comparatively
quantity oi solid aluminum chloride in tower |24
short wide section 20. Other types of isomeriza
so that the amount of aluminum chloride taken
tion reactors such as those having mechanical
up lby the complex may be regulated to any de
mixing means therein or comprising elongated
sired amount. Usually it is desirable to intro
coils. etc., can be substituted if desired, and it is 65 duce the -iortiiied complex into the reaction zone
equally feasible to employ a tower having the
in such amounts that about 0.1 to about 1 pound,
same diameter throughout its length, leaving the
preferably about .2 to .5 pound, of dissolved alu
upper part free of catalyst to act as a “settling
minum chloride is introduced into thefreaction
section” or a separate separator can Ibe employed
zone per barrel of charging stock introduced
for this purpose. The narrow part of the tower 70 thereto.
I9 is filled with catalyst of the type described
The enlarged section 20 of îsomerizer I8 can
approximately to the point where the narrow
act as a “settling section” or separator allowing
portion I9 expands to form the enlarged section
any mechanically occluded catalyst to separate
20. With a tower of uniform diameter the com
out from the hydrocarbons and fall back into
plex may extend to a relatively high level therein; 75 tower I9. The products from'the isomerization
reactor including unconve?ted' normal
une 51; However, »itjisj "ffeq'ue?uy desistere 'ai
recover the Vis‘obutan'e'as a comparativelypure
any' degradation products suchl as propane and
fraction and therefore the normal and isobutane
lighter hydrocarbons, as well as hydrogen chlo
mixture can b_e passed .to fractionator 58 by open
ride, and isobutane pass overhead from isomerizer
I8 through line 29 to line 30 having valve 3| Ci ing valve 59 inline 60. Fractionator 58is any
conventional fractionating equipment for the
therein through cooler 32 to separator 33. The
separation of components of various boiling points
“weight space velocity” in the reactor will vary
ancl'isV provided with the necessary cooling and
widely depending on the activity of the catalyst,
heating means -for separating the normal> butano
temperature of operation, and degree of isomer
i'zation required. In general it will fall within l0 from the isobutane. The desired isobutane passes
the limits of 0.1 to 100 pounds of butane per hour
per pound of aluminum chloride in the reactor.
The volume space velocity for catalysts of aver
age activity (about 60 to 70 large calories per
gram atom of active aluminum in the case of
aluminum chloride) is within the approximate
range of .2 to 4 volumes> of liquid butane charged
per hour per volume of complex in the reaction
z'one or column. The pressure in separator 33 can
be substantially less than that in reactor I8, a
pressure reducing valve 34 in line 30 being pro
vided for this purpose.
Y Separator 33
diagramma-tically illustrates a
separation system for separating hydrogen chlo
ride and gases on one hand and catalyst material
on the other hand from the liquid product stream.
While a single vessel is illustrated in the draw
ings it should be understood that any number of
settling chambers, stripping columns, etc., may
be employed for this purpose. Separator 33 may
be operated at substantially reaction tempera
ture and may act as a combined settler and strip
per. The hydrogen chloride is taken overhead
through line 35, valve 36 in vent line 3l is closed,
valve 38 in line 39 is opened, and valve 40 is
likewise open so that the hydrogen chloride is
simply recycled to line I3. When the gases leav
ing the separator through line 35 contain un
desirably large amounts of gaseous hydrocarbons,
valve 45 may be closed, valve ¿EI opened and the
gases thus passed through line 42 to separator 43
wherein by absorption means or other methods
the hydrogen chloride may be separated from hy
drocarbons. The hydrogen chloride can then be
overhead through line 6Iv to storage (not shown)
while the normal butano is withdrawn through
line 62 and can be recovered as 4such by opening
valve 63 in_line 64,"b'ut preferably is recycledto
the isomerization reactor by opening valvev 65 in
line 66 which joins line Il. Any hydrocarbons
heavier than butane can be withdrawn Vthrough
line 62a and discarded or used otherwise 'as de
- We have thus far described our process as one
employing a single reactor I3. However, itis
often desirable formore complete conversion to
employ the reactorsin series. Accordingly, the
products from line" 29 can` if desired, bedirected
to isomerizer 61 by opening valve 68 in line 69
leading from line 29, valve 29a being closed. The
products pass from line 'I0 to a dispersing means
'II in the elongated tower 'I2 of isomerizer 6'I,
passing up through the catalyst pool to the en
larged portion 13. Catalyst can be added from
line 25 by opening valve 'I4 in line l5. The prod
ucts pass overhead from isomerizer 6'I through
line '16, valve 'I'I being open, to line 39 and the
separator andv fractionator previously described.
Another desirable mode of operation is to em
ploy isomerizer IS‘forr the conversion of normal
butane> to isobutane until the catalyst therein is
degraded to a point where it is no longer par
ticularly effective for promoting the reaction;
When this occurs valve I'I in line I6 can be closed
and valve 'I8 in'line 'I9 opened, directing the feed
stock through line 'I0 to is'omerizer 61. In this
event, of course, valve 2'! in line 26 will be closed,
valve 'I4 in line 'I5 being opened. While isomer'
returned by line 44 and line 39 to line I3 and 45 izer riì'I is “onstream” the'catalyst in isomerizer
I8 can be regenerated and alternatively when
the hydrocarbons vented from the system Ithrough
isomerizer I8 is “on'stream” the catalyst in iso-`
line 45.
merizer B'I can be regenerated.
When cooler 32 apprcciably lowers the temper
' The regenerationis preferably carried out by
ature, for example to 100° F. or lower, most of
the hydrogen chloride may remain in solution in 50 the use of hydrogen only in the pre-sence of an
hydrogen halide, if desired, at superatmospheric
the liquid product but in this- case light hydro
pressures. Hydrogen vfromv any source enters
carbon gases may be purged from the system by
through line 89 and is directed, for example. to
closing valve 38 and opening valve 36 to vent line
the base of tower I9 by opening valve 8l in line
37. In this case, however, a subsequent s-tripping
of the hydrogen chloride out of the liquid product 5 5 82. The temperatures employed for regeneration
will lie within the rangel ef from about 200° F. to
is desirable to avoid unduly large activator losses.
about 350° F. and'pressures of from about 500 t0
Any catalyst carried along mechanically or dis
1500 pounds per square inch are employed,_prefsolved in the products can be recovered from
erably 600 pounds to 1000 pounds per square
separation system 33, the lower temperature serv
ing to precipitate any dissolved aluminum chlo 60 inch. A minor amount of hydrogen chloride can
be added from line E3 by opening valve Sil if de
ride. Entrained complex together with precipi
sired. During the regeneration of the catalyst in'
tated catalyst accumulates as a liquid and may
isomerizer IB valve 3! in line 39 and valve 63 in
be withdrawn through line 46 either through
line 69 will be closed while valve 85 in line 85
valve A‘I and line 48 or preferably through valve
will be open to permit the escape of hydrogen,
.f 49 and line 50 which joins line 25.
which'can Je returned to the hydrogen source
The isomerized product, together with uncon
(not shown). For theregeneration of the cat
verted normal hydrocarbons, is withdrawn from
alyst in isomerizei` 5'! hydrogen input line 8'!
separator 33 through line 5I and passed through
with valve 88 is provided aswell as hydro-gen
wash tower 52 wherein any last remaining traces
of catalyst and/or hydrogen chloride are removed. 70 discharge line 99 having valve 90 therein. Re
generation per se is described in more detail in
Water or an alkali wash, which enters through
our U. S. Patent 2 293,891.
line 53 and is discarded through line 54, can
In another mode cfoperation the catalyst can
be employed. The washed products are with
be continuously or intermittently withdrawn from
drawn from wash tower 52 through line 55 and
can be recovered as such by opening" valve 56 in' 75 isomerizers I8v vand/0r 6'I via lines 9I andl92,
respectively, having valves 93 and’94 therein, to
line 95 while fresh catalyst is continuously added
tion is made between isobutane, propane and
lower boiling hydrocarbons on the one hand
" from line 25. The spent catalyst can ‘be discard
which are withdrawn from the top of the tower
|30 and normal butane, pentane and higher boil
is separately regenerated. To accomplish this, 5 ingrhydrocarbons on the other hand which are
valve 98 in line 99 is opened, the catalyst pass
withdrawn from the bottom of the tower |30
ed by opening valve 96 in line 91 but preferably
ing through heater |99 to regenerator |0|. Hy
drogen is added from line |02 and hydrogen chlo
ride from line ||4, the same conditions of pres
sure and temperature being maintained in regen 10
through line í3| to the normal butane tower |32.
rl‘he eliluent from tower |32 consists predomi
nantly of normal butane although minor amounts
of other saturated hydrocarbons can be tolerated.
erator |0| as were previously set forth for regen
eration of the spent catalyst in the reactors. No
Pentane and higher boiling hydrocarbons are re
moved from the Abottom of the normal butane
tower |32 through line |33. The normal butane
other promoters or regenerating agents are nec
essary, the hydrogen and hydrogen chloride alone
stream is passed through line |34 from the top
serving to reactivate the complex to a liquid mo» 15 of tower |32, through cooler |35 to drum |36.
bile form. The regenerated catalyst plus hydro
Part of the condensed normal butane stream may
gen is withdrawn from regeneratcr |0| which
be returned as reflux to the normal butane tower
has been providedV with a mixer |03 or other
through line |31 while the remainder is passed
means for insuring contact between the hydrogen
through line |38, heater |39 to any one or more
and the catalyst, through line |04 to separator
of the reactors |40, |4|, |42 and |43. If desired
|05, line |04 being provided with a pressure-re
the normal butane stream may be by-passed
ducing valve |06. The hydrogen, with or with
around heater |39 through line |44. An activator
out hydrogen chloride, passes overhead through
line | 01 and can be discarded through line |08
by opening valve |99 or recycled by opening valve
||0 inline ||| which joins line |02. Any hydro
carbons separated from the catalyst by the re
generation step can be discarded through line
||2 while the regenerated catalyst is withdrawn
through line ||3 and directed to line 25 where 30
affording hydrogen halide, such as hydrogen
chloride per se is introduced through line |45 to
the normal butane'stream in line |40 where it is
mixed with the normal butane in amounts of
about l to 10% or preferably 3 to 6% by weight
based on total butane charged. A portion of the
normal butane is withdrawn from line |43 (prior
to the point at which hydrogen chloride is added)
it can be re-utilized in the process. In no case
through line |41 and passed through towers |48
is the catalyst sludge regenerated to 'such an
and |49 which contain solid aluminum chloride.
extent that pure aluminum chloride is formed, as
Additional aluminum chloride may be introduced
has been suggested previously in the art, We
into the towers |48 and |49 at |50 and |5| respec
prefer to use a catalyst in the form of a mobile 35 tively. As shown in the drawings line |41 is pro
complex and not as a pure aluminum halide.
vided with valves |52, |53 and |54 so that the
It is also contemplated that when using the
portion of the normal butane may be passed
reactors in series the catalyst from one reactor
through either one of the towers |48 and |49 or
may be directed to the other reactor, in the event
through vboth towers simultaneously. In the alu
that the catalyst is not substantially or com
minum chloride towers the normal butane dis
pletely spent when it is withdrawn from the re
solves aluminum chloride in amounts controlled
actor. Such a mode of operation is particularly
by temperature and amounts of butane passed
advantageous if the reactors are maintained at
therethrough and this solution passes through
different temperatures, reactor 91 being main
lines |55 and |56 to line |51 whence it is intro
tained in the lower portion of the temperature
duced into any one or more of the reactors |40,
range described and reactor 61 in the upper por
|4|, |42 and |43 through lines |58, |59, |69 and
tion of the range, for example. The higher tem
|6| respectively. Obviously if desired the number
perature will allow the use of the catalyst to a
greater degree of conversion per unit of catalyst,
of reactors may be increased or decreased de
pending upon the size of the reactors, the capac
while the lower temperature permits a greater 50 ity of the system and other factors. The amount
degree of conversion per volume of feed. A part
of aluminum chloride dissolved in the normal
or all of the partially spent catalyst can be di
butane and hence the amount delivered to the
rected from one reactor to another, and alter
reactors is regulated by the amount and tem
natively a part can be sent to one of the reactors
perature of the butane feed passing through the
and the remainder withdrawn for regeneration. 55 towers |48 and |49 so that the activity of the
This can be accomplished by opening valve IIS
catalyst in the reactors may be controlled readily
and easily. It is desirable to introduce from about
sending the partially spent catalyst to the other
0.1 to 1 pound, usually about .2 to .5 pound of
reactor by opening valves ||8 or ||9 in lines ||1
dissolved aluminum chloride into the reaction
or |20,A joining lines 26 and 15 respectively, valve 60 zone per barrel of total charging stock.
| 2| in line 95 being closed. By the proper ad
Each of the reactors |40, |4|, |42 and |43 con
justment of valves ||6 and |2| a part of the cat
tains a column of aluminum chloride-hydrocar
alyst can be routed as above described and a part
bon complex as described hereinbefore. Since
withdrawn for regeneration. Ordinarily, with
the amount of make-up catalyst added and spent
drawal and recycle of thev spent catalyst to the 65 complex withdrawn is quite small, the column of
same reactor without intervening regeneration
complex in the reaction zone is relatively station
or aluminum chloride additives is not contem
ary. The term “relatively stationary” does Vnot
plated since it is expected that the catalyst will
mean “quiescent” because there will of course be
be retained within the reactor until it is no longer
a certain amount of turbulence within the column
effective for promoting the isomerization reac 70 itself. The term “relatively stationary” means
rather that the catalyst column is relatively ñxed
Another system for isomerizing normal butane
or stationary with regard to charging stock flow
is shown in Figure 2. In this figure the feed con
as distinguished from concurrent and counter
taining normal butane is introduced through line
current iiow respectively. This column should be
l 29 >to the isobutane tower |30 in which a separa >75 at least about 5 feet in depth and should prefer
in line || 5 which leads from lines 9| -or 92 and
ably _be about 20 to‘30 feet. As .shown inthe
drawingsA the normal butane is introduced at a
low point in the column while the make-up alu
minum chloride dissolved in a portion of the bu
tane feed is introduced at a higher point in the
column. The conditions existing in the reactors
are similar to those previously mentioned and are
favorable to the isomerization of normal butane
to isobutane; the pressure is suñicieht to main
_tain liquid phase conversion conditions, i. e. is
wit`.in the approximate range of 100 to 2000
pounds preferably about 300 to 600 pounds per
_square inch and the temperature is within the
gasesçwill be very small because under the con
ditions in accumulator |99 the hydrogen chlo
ride is enieny dissolved in the liquid productl
The overhead from the isobutane tower |30
contains not only the isobutane produced by the
system but also any isobutane which may be pres
ent in the feed in line |29. In addition, the over
head may contain propane. The overhead is with,
drawn through line |92, condensed in cooler |93
and introduced into tank |90, A portion ¿of- the
condensate may be pumped back to the isobutane
tower as reflux while another proportion is passed
approximate range of 120° F. to L100“ F., prefer
ably about 200° to 250° F. As stated above we
prefer to operate our process in the liquid phase
although we may also operate in vapor phase.
The space velocity with a catalyst of good activity
Ashould be within the approximate range of .2 _to 4
through line |95 to the depropanizer |96. The
bottoms from the depropanizer consist essentially
of isobutane and can be withdrawn through line
|91> to storage. The overhead from'the Vdcpro
panizer, consisting of propane and any lower boil-,
ing hydrocarbons that> may be present, is with
A5 in the case of the system illustrated in Fig
ure 1 the butane stream passes upwardly through
volumes of total butane charged per hour (liquid 20 drawn through line |98 and cooler |99 to‘reñux
drum 209 from which a portion of the condensate
basis) per volume of complex in the conversion
may be returned to the depropanizer as reñux and
zone. rl_`he vertical flow rate may be about 0.1 to
another portion withdrawn through valve‘d- line
1 foot, e. g. about .5 foot per minute.
the reactors as a dispersed phase in a continuous
The spent catalyst complex may be withdrawn
from the reactors i610, MI, |42 and |43 through
by line |66 through a pressure reducing valve |91,
catalyst complex may be withdrawn from the
lines 202, '203, 204, 205 and line 206 to catalyst
complex phase. At a point near the top of the
drum 201. Likewise active catalyst complex may
reactor the products of isomerization form a con
also be withdrawn from any one or more ’of the
tinuous phase and any catalyst complex which
is carried into this phase will tend to settle out 30 reactors to the storage drums when occasion de
mands and such active catalyst- may be returned
and return to the continuous complex phase in
to any one or more of the reactors by means of
the lower part of the reactor. The products of
pump 298 and line 209 and thence through line
reaction are removed from the top of the reactor
20,6 and lines 202, 203, 204 and/0r 205. Spent
through lines |62, |63, |94 and |65 and thence
catalyst drum through line 2|0. When 'spent
complex is withdrawn to drum 201 it passes
through a pressure-reducing valve in line 206
which permits the escape of hydrogen chloride
about 40 to 100° F.
Settled catalyst complex may be returned to 40 and hydrocarbon gases released by the reduction
a cooler |078 to an accumulator |69 which may
be operated within the range of about 90 to 150
pounds gage pressure and at a temperature of
the reactors through line |10, pump |1| and lines
|12, |13, |14 and |15. That portion of the liquid
products which passes over the bañie |16 in the
accumulator |99 is pumped through line |11 to
column |18 wherein the hydrogen halide acti
vator is stripped. Column |18 may be operated
at a pressure of about 450 with a top temperature
of about 125° F. and a bottom temperature of
about 270° F. The activator is withdrawn from
the top of the stripping column |18 through line
|19 and returned to the normal butane feed pass
ing through line |46.
The bottoms from the stripping column |10
are Withdrawn through line |30, cooler |8| and
subsequently purified by caustic which maybe
of pressure on the complex.
These gases are
vented through line 2| i. To prevent corrosion
and colring in drum 201 the spent complex is
protected from moisture and air by gas blanket
ing the drum with either dry inert or hydrocar
bon gas introduced through line 2 | 2.
As an example of the process according to the
present invention a plant stream consisting pre-v
dominantly of normal butane was charged
through `line |29 at the rate cfV one gallon per
hour for sixty hours to the isobutane towerI |30.
The bottoms 'comprising normal 'butane and
higher boiling hydrocarbons were subsequently
fractionated in tower |32. The. normal butane
stream which was taken overhead through line
|34 and subsequently passed> through line |38 was
heated by' heater |39 to a temperatures of ap
proximately 170°> F.. This lontane stream which
includes recycle normal butane derived from line
through line |94, or, if desired, in the case of only
partially spent caustic, it may be recycled to the 60 |90 is. fed to the> reactors at the -rate of approxi
mately 1.8 gallons per hour, Approximately 50%
settler through line |85. The treated products
of the normal butane stream in line |46 is passed
are withdrawn from the caustic settler through
through the aluminum> chloride drums |48 and
line |05 admixedwith wash water which is intro
|49 wherein a solution of aluminum Vchloride in
duced through line |81 and passed- through a
mixer to a water settler |99 where a separation 65 normal butane is formed. During the 60 hour
run .4 pound of aluminum chloride was dissolved
occurs; the water being withdrawn through line
by the normal butane. This is equivalent to -a
|99. The product which hasY thus been washed
product yield of 105 gallons of isobutane per
is passed via line |90 to the isobutane tower |39.
pound of make-up aluminum chloride. Hydro
During the course of the isomerization reaction
gen chloride was added to the normal butane
various gaseous products may be formed which
stream through line |45 in an amount equal to
must be vented from the system in order to pre
4.5 weight percent of reactor charge, The space
vent the accumulation thereof in the system. A
velocity within the reactors was rapproximately
vent is provided on the accumulator |09 and such
0.8. »In order to effect the isomerization ofV the
gases may be removed from the system by. line
|91. The loss of hydrogen chloridewith these 75 normal butane the reactors were maintained- at
introduced through line |82 and this mixture is
passed through a mixer to a caustic settler |83
from which spent caustic may be withdrawn
a temperature of about 215° F. and at a pressure
of about 400 pounds per square inch. The prod
uct stream in line |66 passes through the pres
sure reducing valve |61 to the accumulator |69.
The conditions therein are maintained 'at ap
proximately 90 to 100° F'. and 290 pounds per
square inch. After separation from any catalyst
complex which may have been carried over the
product stream is passed to the stripping column
plex in amounts suñicient to maintain the hydro
carbon content of the complex within'the range
of about 16% to about 40% by weight.
3. The method of converting normal butane to
isobutane which method comprises continuously
introducing a normal butane charging stock at a
low point in a relatively stationary column of liq
uid aluminum halide paraffinic hydrocarbon
complex, introducing a small amount of a hydro
|73. This column was maintained at a pressure l0 gen halide activator into said column of complex,
of about 300 pounds per square inch and had a
maintaining said column at a temperature effec
top temperature of 95° F. and a bottom tempera
tive for converting normal butane to isobutane
ture of 235° F. In this case a recycle hydrogen
and maintaining a column height suñicient to
chloride was sent to an adsorber. The bottoms
effect substantial conversion as the butane passes
from the stripping column were after purification 15 upwardly therethrough at a temperature below
returned Ato the isobutane tower |30. It was
about 300° F. and at a pressure suiiâcient to main
found that whereas the charging stock for the
tain the butane in liquid phase, continuously re
reactor contained only approximately 9% isobu
moving reaction products at conversion pressure
tane the product stream in line |90 contained
and in liquid phase from said relatively station
approximately 48% isobutane, The overhead 20 ary column to a settling zone of suñ‘ìcient cross
from the isobutane tower was stripped to remove
sectional area to permit the settling out of a sub
lower boiling hydrocarbons and the isobutane
stantial amount of entrained complex from liquid
product, containing 93% isobutane, was obtained.
butanes leaving said column, adding make-up
While we have illustrated our invention by ref
aluminum halide to said complex iny amounts
erence to the specific iiow diagrams, it `should be 25 sufficient to maintain the hydrocarbon content
emphasized that these are by way of illustration
of said complex within the range of about 16%
only and not limitations on the scope of our in
to about 40% by weight separating activator and
vention. Moreover, for the sake of simplicity,
any residual catalyst from liquid reaction prod
various details have been omitted from the draw
ucts and fractionating said products to obtain a
ings and description, such as heat exchange fea 30 fraction consisting essentially of isobutane.
tures, pumps, valves automatic control means,
4. The method of converting normal butane
etc., which omissions will be readily understood
to isobutane which method comprises maintain
and supplied by one skilled in the art wishing to
ing a column of liquid aluminum halide-par
practice our invention.
aftinic hydrocarbon complex in a reaction zone,
35 incorporating an aluminum halide into said com
We claim:
1. The method of producing isobutane which
plex in amounts sufficient to maintain a hydro
method comprises reacting a saturated hydrocar
carbon content in said complex within the range
bon with aluminum chloride in the presence of
of about 16% to about 40% by weight, intro
hydrogen chloride under conditions for producing
ducing a normal butane charging stock into said
a liquid aluminum chloride hydrocarbon com
40 reaction zone at a ñrst level at a low point in said
plex having a hydrocarbon content within the
range of 16% to 40% by weight based on total
complex, continuously contacting a charging
stock consisting chieñy of normal butane and
substantially free from oleiins with said complex
column, said column extending from said lirst
level up to a higher second level, introducing a
hydrogen halide activator in said column, passing
liquid charging stock upwardly through said col
umn as a dispersed phase in said column of com
in the presence of a hydrogen halide activator
plex between said iirst level and said second level,
maintaining a separation space in said reaction
zone above said second level wherein complex
under conversion conditions of temperature, pres
sure and space velocity for effecting isomeriza
tion, continuously separating hydrocarbon prod
may separate from upiiowing liquid conversion
ucts from said complex at substantially con 50 products and be returned to said column of com
version temperature and under a pressure suffi
plex, withdrawing reaction products at a third
cient to maintain at least a part of said product
level which is higher than said second level in
in a liquid phase, and adding make-up aluminum
said conversion zone and separating hydrogen
chloride to said complex employed in the contact
halide and any residual catalyst from the with
ing step at such a rate as to maintain the hy 55 drawn products.
drocarbon content of the complex within the
5. The method of converting normal butane to
range of 16% to 40% by weight.
isobutane which method comprises contacting in
2. A process for the conversion of normal bu
a reaction zone a normal butane charging stock
tane into isobutane which process comprises
substantially free from oleñns with a liquid alu
maintaining in a conversion zone a relatively sta
minum chloride-paraiìnic hydrocarbon complex
tionary column of liquid aluminum chloride
parafiinic hydrocarbon complex at isomerization
temperature and under suiiicient pressure to
maintain liquid phase conversion conditions in
said coulmn, continuously introducing a normal 65
containing an amount of hydrocarbons within
the range of about 16% to about 40% by weight
based on total complex, eiîecting said contacting
at a temperature within the range of 120° F. to
butane charging stock at a low point into said col
umn, introducing a hydrogen chloride activator
into said column, passing chargingstock as a dis
400° F. and under a pressure of at least about 100
pounds per square inch and sumcient to main
tain a liquid hydrocarbon phase in said reaction
zone, introducing hydrogen chloride into said
persed phase upwardly through said column, con
reaction zone in amounts within the range of .1
tinuously separating complex from butanes leav 70 to 20% by weight based on charging stock, em
ing the top of the column, continuously return
ploying a space velocity within the range of .1
ing separated complex to the upper part of said
to 100 pounds of butane per hour per pound of
column, continuously withdrawing separated bu
aluminum chloride in the reactor, adding alumi
tanes at a point above the top of said column and
num chloride to said complex in amounts suffi
adding make-up aluminum chloride to the com 75 cient to maintain the hydrocarbon content of
said complex within said range of about 16% to
about 40% during the conversion and removing
catalyst and activator from reaction products.
6. The method of claim 5 wherein the con
version temperature is in the general vicinity of
about 200° F., wherein the conversion zone 'is un
der` suñîcientpressure to maintain substantially
liquid» phase
conversion conditions, wherein
charging 'stoclc‘stream consisting chiefly of nor'
mal butane and substantially free from oleiins at
a low level in a relatively stationary column of
liquid aluminum chloride-parai’ñnic hydrocarbon
conversion zone, employing in said
column a complex having at least 16% by weight
but not more than 40% by weight hydrocarbon
component in its composition, adding a hydrogen
halide activator to the column, passing the dis
make-up aluminum chloride is introduced to the
reaction zone at the rate .of about .l to 1 pound 10 persedv charging stock upwardly through the col
umn under conversion conditions of temperature,
perubarrel. of total charging stock introduced
pressure and space velocity for effecting isomeri
thereto,whereinhydrogen chloride is introduced
Zation, fortifying said complex to maintain it in
into. saidconversion zone at the rate within -the
range,..of~about 3% to 6% by weight based on
total; charging stock and wherein the space ve
locity.- is within the vrange of„.'.2 to 4 volumes of
charging-‘stock per hour per volume of complex
active state by adding aluminum chloride thereto,
15 separating hydrocarbons as a liquid phase from
the column of complex and continuously with
drawing a hydrocarbon stream from the upper
part of saidconversion zone.
in‘- the conversion zone.
l1. The method of claim l0 wherein the rate
»FLA‘The‘ method; of. claimA 5 wherein said con
tacting is effected by introducing said charging 20 of aluminum chloride addition is within the
range of .l to l lb. per barrel of stock charged.
stock at-the Ybase ‘of a‘column of liquid catalyst
12. The method of claim 10 wherein the rateof
complex which is at least about 5 feet in height.
aluminum chloride addition is such as to main
. 8. >The method of-.olaim Y5 wherein saidy con
tain in the composition of the complex at least
tacting `is effected'by introducing said charging
stockA at `the base ci a column of_ liquid catalyst 25 about 16% but not more than about 40% by
weight of hydrocarbon components.
complex .which is within the range of 5 to 30 feet
13. The method of producing isobutane which
in height.
comprises continuously passing a charging stock
9.. The method ci producing isobutane which
consisting chieñy of normal butane and substan
method comprises continuously dispersing a
charging stock stream consisting-chiefly of nor 30 tially free from olefins upwardly through a col
umn of liquid aluminum chloride-paraffinic hy
mal butane and substantially free from oleñns at
drocarbon complex in the presence of added hy
a low level into a relatively stationary column of
drogen chloride at a temperature, pressure and
liquid aluminum halide-paramnic hydrocarbon
space velocity for eiîecting isomerization under
complex in'a conversion zone, employing in said
column a complex having at least 15% by Weight 35 liquid phase conversion conditions, producing said
complex by reaction of aluminum chloride in the
but not more than 40% by weight of hydrocarbon
presence ofhydrogen .chloride with a saturated
component in its composition, adding hydrogen
hydrocarbon which is substantially free from ole
halide activator to said column, passing said dis
?lns and aromatics and by employing an amount
persed charging stock upwardly thro-ugh said col
umn under conversion conditions of temperature, 40 of reactants in said complex producing step so
that the complex kin the isomerizing step will
pressure and space velocity for effecting isomeri
have a hydrocarbon content within the range of
zation, fortiiying the complex by addition of alu
16% to 40% by weight based on total complex,
minum halide `for maintaining its activity, sepa
and maintaining the activity'of the complex dur
rating hydrocarbons as a liquid phase from the
column of complex, and continuously withdraw 45 ing the continuous passage of charging stock
ing separated hydro-carbons from the upper part
of said conversionzone`
10. The method _of producing isobutane which
method comp-rises continuously dispersing a
therethrough by adding make-up aluminum chlo
ride to said complex.
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