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Патент USA US2407489

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Sept. 10, 1946‘
w.‘ B. FRANKLIN
'
ISOMERIZATION' PROCESS
'Filed Jan. 22, 1944
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Patented Sept7 10, 1946
2,407,488
UNITED .STAT ES
OFFICE
William B._ Franklin, Baytown, Tex,‘ assignor to
Standard Oil Development Company, a corpo
ration or Delaware
Application January 22, 1944, Serial No. 519,306
1
4 claims. (01. 260-6835)
.
The present invention relates to a process for
'2 .
}
employed may be formed by admixinggranules
or lumps of aluminum chloride with the desired
the catalytic isomerization of paraf?nic hydro
carbons, More particularly, it relates to the cat
quantities of dehydrated ‘Porocel and the mass
alytic isomerization of normal para?inic hydro~
heated while passing therethrough a stream of
carbons- having ‘at least four .carbon atoms in
inert vapor or gas such as nitrogen, carbon di
the molecule wherein feed stocks predominating
oxide, hydrogen, methane, ethane, propane, bu
in these types of hydrocarbons are subjected to
tane and the higher para?inic hydrocarbons.
the action of éFriedel-Crafts type catalysts in the
Or the mass may be produced in situ by charging
presence of halogen-containing promoters under
a suitable reactor with a quantity of dehydrated
suitable vapor phase isomerization reaction con‘ 10 Porocel and then employing the heretofore-men
ditions to produce the corresponding branched
tioned vapors as a carrier for aluminum chloride
chain para?inic hydrocarbons.
vapors which are introduced and passed through
Straight chain para?ins of at least four car
the bed of ‘Poroce‘l. The Porocel'then sorbs the
bon atoms per molecule have been ,isomerized in
aluminum chloride and the catalyst is thus
the presence 'of Friedel-Crafts type catalysts and
formed. Stillother methods have been employed
halogen-‘containing promoters to produce
in the past in order to make up the aluminum
branched chain para?ins. Numerous e?orts have
chloride-alumina catalyst composition for use in
been made in the past to increase the efficiency
vapor phase ‘and liquid phase normal para?ln
of the catalysts employed, particularly in an ef
isomerization
reactions. Similar methods may be
fort to minimize the degradation of the catalyst 20 employed in reactivating
a catalyst mass which
as well as the degradation of the feed stock while
has previously been employed in isomerization
reactions but which has decreased materially in
its catalytic activity and thus requires further
in contact with the catalyst. By so doing, an in
creased catalyst life is attained as is manifested
by a greater yield of isoparaflins per pound of
treatment in order to bring it back to a practical
catalyst employed. Particularly in commercial
operations, petroleum re?neries have large quan
isomerization level. This may be accomplished
by adding vapors of aluminum chloride or lumps
of aluminum chloride and vaporizing as hereto
fore described. No problem was apparent in ac
complishing this treatment in pilot: plant and
tities of light hydrocarbon mixtures available,
but there recently has sprung up a greaterde
mand for the isoparaf?nic hydrocarbons than
for the normal para?‘inic hydrocarbons, making it 30 laboratory scale operations, but considerable dif
vnecessary to incorporate isomerization facilities
?culty has been encountered in accomplishing
in the ordinary re?nery in order to obtain in
the
same operations Where commercial scale
creased amounts of the isoparaf?ns which serve
units are concerned.
}
notonly as blending agents for the normal par
It is an object of the present invention to min-i
a?ins but also as intermediates ‘and reactants in ‘ mile catalyst degradation in a large scale normal
the preparation of normally liquid hydrocarbons
which also are useful in motor fuels.
para?in isomerization operation involving the
.
vuse of a catalyst mass of aluminum. chloride
The vapor phase isomerization or normal par
a-f?ns such'as, for example, normal butane, to
isobutane, takes place with ease in the presence
sorbed in a porous alumina, while at the same
vof hydrogen halide promoters such as hydrogen
time maintaining substantially the same condi
tions in the ‘catalyst ‘chamber during the reacti
chloride, where a catalyst'comprisin'g essentially
vation or revivi?cation of the catalyst mass as
aluminum chloride sorbed ‘in an alumina is em
are maintained in the isomerization reaction
ployed. Ordinarily a catalyst bed is made up of
proper. 'By such a procedure a minimum oper
V Porocel or ‘some other suitable highly porous 45
alumina. This sorptive alumina 'is usually ?rst
treated ‘at temperatures ranging from 400° F. or
alyst back to a practical operating activity and in
500° F. up to as high as ‘1100" F. or 1;_200°¢F.‘f-or a
vperiod of hours ranging between about 1v and
about 5 or‘6 in order to ‘remove all traces of free
water which may 'be contained in ‘these alumina
carriers, since it has been found that free water
- in the presence of aluminum chloride tends to
hydrolyze the aluminum ‘chloride and thus lower
ational loss results both from the standpoint of
time involved in bringing the partially spent cat
' labor required to accomplish the revivi?cation
‘and reactivation of a partially spent aluminum
.50
'chloridecat‘alys‘t mass. It is a further object of
the invention to minimize the overall time ‘re
.quiredto maintain a practical isomeri‘zin'g cata
lyst mass at any desired practical operating level
-.of activity and to thus secure improved yields of
its overall catalytic activity. The catalyst mass .55 product per pound of aluminum chloride em
2,407,488
3
zone are altered over those employed in the isom
erization reaction proper but the hydrogen chlo
ride is withheld from its entry into the isomeri
zation reaction zone while the normal butane is
played and per unit of time of operation of any
particular unit.
‘
In the past, admixtures of normal butane and
hydrogen chloride, for example, have been fed
being fed, together with vapors of aluminum
to an isomerization reaction zone by passing the Cl chloride, into the catalyst bed for the purpose of
feed mixture through a superheater and into the
reactiyating the‘same. It is not necessary, how
catalyst massat the desired reactiontemperature
ever, that the normal butane be employed as the
under the ‘desired rate of throughput. 'Once the
carrier, but it is in practical operations the most
isomerization catalyst mass becomes degraded in
convenient carrier since it or other suitable nor
activity to a point where it is no longer practical
mal paraf?ns of at least four carbon atoms per
partially
deactivated
.~
to utilize the same in its
vmolecule is being employed as the feed stock to
condition, it is necessary either to dump thecata
the reactor. Any inert gas such as carbon diox
lyst and employ freshly prepared catalyst or to
ide, nitrogen, vhydrogen and the like, may also be
suspend operation su?‘iciently longto reactivate '
employed,,provided, however, that no halogen
or revivify that catalyst in order to‘bring it back
containing promoter is added to the reactor at
to a practical level of isomerization activity.
1
the,
same time. ‘Small amounts of hydrogen
From an economic standpoint, it is preferable vto
chloride will remain in the Porocel bed during the
employ the latter expedient. It is known to em
addition, ‘but the introduction of the aluminum
ploy the admixture of normal butane and hydro- ' J chloride vapors and carrier gas therein tends to
20
gen chloride, that 1s, the- feedstock to the isomer
‘purgethe reactor of the unabsorbed hydrogen
' ization unit, as a carrier medium for picking up
chloride'contained in that bed and no difficulties
sublimed aluminum chloride vapors and intro
such. as the formation of' aluminum chloride
ducing them into the catalyst mass. It is also
~hydrocarbon complexes develop. There is rela
known to employ'various other expedients for
tively no increase in pressure drop across the cat
accomplishing the reactivation of the catalyst
alystbed when this expedientis employed.
mass but in each case it hasbeen necessary to
The accompanying drawing illustrates in more
alter the reaction zone containing the deacti
or less diagrammatic fashion a flow plan of a
vated catalyst mass from the'isomerization con
commercial isomerization unit, and for the pur
ditions customarily maintained on that reactor.
poses of illustration only the operation of this
30
By-practicing these expedients, a lowering of the
isomerization plant will be described with refer
temperature of the catalyst bed is-usually re
ence to a feed stock of normal butane, the pro
quired in order to minimize the formation of
moter being hydrogen chloride, the vcatalyst alu
sludge and hydrocarbon-aluminum chloridecom
' mmum chloride sorbed on Porocel. Various feed
plexes which seem to form rapidly under such
stocks, such as straight run naphthasnormal
butane, normal pentane and higher straight chain
conditions with a resulting reduction in the life
‘of' the catalyst. 'In an effort to overcome these
obstacles,-a new method of reactivating the cata
lyst mass was tried in which the normal butane
was permitted to pick up vapors of aluminum
chloride and the resulting mixture was then in
troduced with hydrogen chloride into the isomer
ization catalyst bed'under the isomerization con
ditions obtaining. Although the aluminum chlo
ride was successfully sorbed- in the pores of the
paraf?nic homologues, ?eld butanes, normal bu
tane cuts from alkylation units, and the like, are
suitable feeds for the isomerization process. Also,
~10 other halogen-containing promoters which are
well known in the art may be employed. De
pending upon the impurities in the feed stock, it
may be desirable to treat the same with corn
centrated sulfuric acid of 90-100% strength in
order to remove water. sulfur and sulfur-contain
porous alumina, a considerable complex forma- .
ing impurities. and it is usually desirable after
such treatment to percolate the feed stock, pref
erably in liquid phase, or in vapor phase, through
tion took place at the point of entry vof these va
pors into the porous'mass, resulting in a subse:
quent extremely high pressure drop‘ across the
a bed of sorptive alumina in order to remove the
catalyst bed even when further -quantities_
of aluminum chloride vapors were subsequently
left out of the feed stream going to the
isomerization reaction zone. This dif?culty be
last traces of sulfuric acid, sulfur-containing
esters and sulfonates, and the like, since they
have been found to exert a deleterious influence
upon the aluminum chloride.
came so serious that it was necessary to dump
Such a feed stock, in the absence of hydrogen
chloride, and having a composition of
Percent
the entire catalyst bed, which, in the particular
case, amounted to 52,800 pounds of calcined
Porocel and about 5,600 pounds of aluminum
chloride.
C3 and lighter __________________________ __
This of course represented a serious
0.0
Normal butane _____________ _____________ __ 96.5
economic loss.
‘
-
'
The present invention is based upon the dis
covery that the isomerization reaction conditions
do not have to‘be materially altered in order to
successfully introduce vapors of aluminum chlo
ride into a partially deactivated catalyst mass
and at the same time the feed stock going to the
3.0
Ca and heavier _________________________ __
0.5
is introduced into the system through line 2', con
trolled by valve 3, and ?ows through heater 8
where it is raised to a temperature of between
about 220° F. and about 400° F. Anhydrous hy—
drogen chlorideis introduced into the system
through line 4, controlled by valve 5,.passes
through line 6, controlled byfvalve ‘I, and is ad
isomerization reaction zone may be employed as
the carrier mass‘ for the aluminum chloride va
pors. It has now been discovered that the essen
tial feature of adding these vapors, using normal
butane as the carrier therefor, to a catalyst bed
maintained under isomerization reaction condi
Isobutane ____________________________ _'___
70
mixed with the feed stock in line 2. The feed
mixture then passes through the heater as before
described and is introduced, by means of lines’?,
H] and 28, into the inlet sleeve 40 of the‘reactor
39 and passes into a catalyst bed substantially
' zone while the aluminum chloride vapors are be
?lling reactor 39 by ?rst going through a per
ing introduced. In‘ other words, in a commercial
forated steel tube 5% which acts as a distribut
75
operation no reaction conditions on the catalyst
tions lies in the fact that thehydrogen chloride
must be withheld from addition to the reaction
2,407,488
16
ing means for the mixture. A perforatedplate
valve 50. Permanent gases which may have been
above the feed inlet may also serve asthesup
port for the catalyst bed in place of tube 4 I. _ Re
actor 39 is charged with about 52,800 pounds of a
low iron content calcined Porocel of from 4 to 8
formed in the system may be withdrawn through
line 41, controlled byv valve 48. r The hydrocarbon
reaction product is then passed through line 5!,
controlled byv valve 52; into stripping column 53,
mesh and containing about 1.58% of volatile 0 wherein
the hydrogen chloride and some hydro
matter by reason of its having been pretreated
carbon vapors are removed overhead through line
to a temperature of about 1000-1100° F. forap
54 and may be withdrawn from the system
proximately one and one-half hours in order to
through line 55, controlled by valve 56. Prefer,
remove any free water which might be evolved l0 ably, however, they are recycled to the reactor 39
otherwise during the isomerization reaction.
through line 5?, controlled by valve 58, and line
Granular aluminum chloride was dispersed even
30, controlled by valve 31. The bottoms from
ly throughout the lower two-thirds of the Porocel,
stripper 53 are passed by means of line 59, con
while the remaining one-third of the Porocel in
trolled by valve 60, into mixer 6i. Caustic soda
the upper portion of the bed. contained no alumi
num chloride. The aluminum chloride was then
sublimed and sorbed on the Porocel by blowing a
portion of the normal butane vapor, heated. to
about 340° F., through the bed at a charged rate
15 solution or suitable alkaline material is intro
of about 4500 gallons per hour at atmospheric .
pressure until the temperature of the bed reached
about 335—340° F. After reaching this tempera
ture the treatment was continued for about 12
hours except the pressure within the reactor was
maintained at 40-50 pounds per square inch.
During the time the normal butane was being
passed through the reactor as above described,
Valves 7 and I4 remained closed so that no hy
duced into the system through lines 01 and 69,
controlled by valves. 68 and 10 respectively, and is
admixed ‘with the bottoms from stripper 53 in line
55%. Mixer 5| is provided with conventional mix
ing plates and the vtreatment in mixer 6! is de
signed to remove the last traces of aluminum
chloride and hydrogen chloride contained in the
product. This mixture is passed through line 62,
controlled by valve 63, into settler 04, where the
aqueous caustic solution introduced into the sys
tem though line 59 settles to the bottom and is
withdrawn from settler 54 through line 65, con
trolled by valve 65. It may be either returned to
drogen chloride except that which might be in
the mixing chamber 6! through line 6?, controlled
cidentally produced during the catalyst formation 30 by valve 68, or, if it is spent, it may be with
period was present in the reactor 39. After the
drawn from the system through line 69, controlled
period of catalyst formation, however, the hydro
[by valve 70. The neutralized hydrocarbon mix
gen chloride was introduced through lines 4 and
ture is withdrawn as an upper layer from settler
8 so that the ?nal feed composition entering line
64 through line ‘H, controlled by valve 72, and is
28 and feed sleeve 40 contained between about 2 35 passed into the fractionating tower 13 wherein
and about 8 weight per cent based on the nor
the residual quantities of propane and lighter
mal butane being charged.
products may be taken overhead through line 74,
During the period ofrcatalyst preparation, the
controlled by valve 15; or, if there are none, then
reactor was maintained at a temperature slightly
the tower may be operated 'so that the desired
higher than that to be employed in the isomeriz 40 product of the reaction. namely, isobutane, is
ation reaction proper, and upon the introduction
withdrawn through line 14, controlled by valve 15.
of the hydrogen chloride the reaction tempera
If appreciable quantities of light degradation
ture was allowed to drop to about 220° F. In gen
products are separated in fractionating tower 73,
eral, a bottoms temperature of about 220-350° F.
then the product of the reaction, namely, isobu
is desirable in reactor 39. The lower temperature
tane, may be withdrawn through line '16, con
is preferred for initial operation of the catalyst
trolled by .valve H. The bottoms from tower 13
bed while the higher temperature may be used
comprise essentially normal butane together with
during later operation when the catalyst is less
small amounts of C5 and heavier para?ins. These
active. A feed rate through the reactor of be
may be withdrawn from the tower '13 through line
tween about 3000 and about 6500 gallons of nor_ 50 ‘i9, controlled by valve 80, and withdrawn from
mal butane per hour was maintained during the
the system. Generally, however, these bottoms,
isomerization reaction and about 5600 pounds of
comprising essentially normal butane, may be re
aluminum chloride was employed in making up
cycled to feed line 2. However, a distillation op
the initial catalyst mass. This amounted to,
eration is desirable to remove the small amount
roughly, 10 weight per cent of aluminum chloride 55 of pentane or heavier'hydrocarbons formed in re
in the total catalyst mass. However, the catalyst
actor 39.
mass may be operated satisfactorily if it contains
It may be ‘desirable at times to introduce the
between about 5 and about 20 weight per cent of
hydrogen chloride in line 4, controlled by valve 5,
aluminum chloride. The actual amount of alu
into admixture with the normal butane feed at a
minum chloride depends to a large extent upon no point as close to the points of entry of the reac
the porosity of the speci?c porous alumina em
tants into reactor 39 as possible. This may be ac
ployed. It isnot desirable, however, to maintain
more aluminum chloride in the catalyst mass than
may be completely sorbed therein under the isom
erization conditions obtaining.
The reacted e?luent passes from reactor 39
through line 42, containing valve 36. The reacted
eiiluent is passed through cooler 43, wherein the
complished by closing valve 7 and opening valve
I4, permitting the hydrogen chloride to ?ow
through line I2.
In such an operation as has just been described,
wherein the unaltered catalyst mass was em
ployed over a long period of time, the yield of iso
butane in the product amounted to an average
ranging between about 32% and 41% of the re
temperature is reduced and the cooled mixture in
liquid phase is then passed through line 44, con 70 acted mixture. However, eventually the yield of
trolled by valve 45, into the product accumulator
46 wherein any liquid or solid particles such as
aluminum chloride or the degradation product of
aluminum chloride with hydrocarbons may be
. isobutane dropped below this ?gure, making it
uneconomical to continue on-stream for a longer
period of time without reactivating the catalyst
mass.
This reactivation was accomplished by
withdrawn through the outlet 49, controlled by 75 withholding the hydrogen chloride entry into re
‘2,407,488
7
actor 39. In other words, valves 1 and I4 were
closed and the hydrogen chloride stream from
stripper 53 ?owed through lines 54, 51, $2 and 34
while valve 31, in line 30, and valve 35, in line 35,
were completely closed. As aluminum chloride
vapors are introduced into the reactor 39 in the
manner to be hereinafter described, hydrogen
chloride and hydrocarbon vapors may be vented
from the system through line 41, controlled by .
valve 48, in order to maintain an even pressure
on the reactor. Several thousand pounds of gran
ular aluminum chloride are introduced into alu
minum chloride pickup chamber l9 through line
8
bon atoms per molecule in admixture with pro
motional amounts of hydrogen chloride under
isomerization reaction conditions by passing said
‘admixturethrough a catalyst bed comprising es
sentially aluminum chloride sorbed on an at least
partially dehydrated porous alumina, said alumi—
na being substantially incapable of evolving free
water under the isomerization reaction conditions
obtaining, continuing said isomerization until the
catalyst activity falls below the desired level,
withholding the introduction of hydrogen chlo
ride into the catalyst bed while at the same time
introducing vapors of aluminum chloride into the
catalyst‘ bed employing normal paraffin feed stock
20, controlled by valve 2!. Valve H is partially
as the carrier therefor, the catalyst bed being all
15
closed and part of the normal butane feed, after
the while maintained substantially‘under isomer
passing through heater 8 and into line 9, passes
iZation reaction conditions, stopping the alumi
through line H, controlled by valve l8, and
num chloride introduction when the catalyst bed
through aluminum chloride pickup chamber l9,
has had introduced‘ thereinto sufficient quantities
which is maintained at a temperature of between
of aluminum chloride so as to materially increase
about 220° F. and about 350° F. The vapors of
its isomerization activity but before saturation of
aluminum chloride and normal butane pass from
the alumina with aluminum chlorideunder the
aluminum chloride pickup chamber l0 through
isomerization conditions obtaining has been
line 24, controlled by valve 25, and are then intro
reached, and resuming the original isomerization
duced into reactor 39 by means of line to and line
process by feeding an admixture of normal paraf
28, controlled by valve 29, valves 35 and 3! re
?n feed stock and hydrogen chloride to the said
maining closed while valve 33 remains open. Aft
catalyst bed substantially under the original
er between about 1000 and 2000 pounds of alumi
num chloride have been added over a period of
isomerization reaction conditions. v
2. A process as in claim 1 wherein the feed
several hours, the aluminum chloride pickup
stock comprises essentially normal butane and
drum I9 is by-passed and the catalyst tempera 30 the alumina is a dehydrated bauxite containing
ture, as heretofore mentioned in connection with V
between about 7% and about 14% of aluminum
reactor 39, is reduced as stated therein, then the
chloride.
'
hydrogen chloride recycle in line 51 is permitted
3. In a continuous isomerization process in
once again to ?ow into reactor 39. In other
which a normal paraflin of at least four carbon
Words, at any time that hydrogen chloride is ?ow 35
atoms per molecule in admixture with promotion
ing through line 28 no aluminum chloride is flow»
al amounts of hydrogen halide are contacted un
ing into the system through line 9.4; and, con"
der isomerization reaction conditions with a cata
versely, if at any time aluminum chloride is ?ow
lyst comprising a porous support carrying alumi
ing into the system through line 24, then valves
num halide, the step of replacing, at intervals in
1, M, iii and 35 remain closed. This has been
dicated by decrease in activity of the catalyst, the
found highly advantageous, an d, curiously
hydrogen halide in the feed mixture with anhy
enough, some residual hydrogen chloride is still
drous aluminum halide without substantially al
in reactor 39, as evidenced by the fact that while
tering the conditions; of operation, the replace
the aluminum chloride vapor is being passed into
reactor 39 some 20%—25% of iso-butane is pro
duced during the operation. However, the pres
sure drop, upon placing the reactor 39 on stream
again, was substantially the same as that encoun
tered in a fresh charge of catalyst to the reactor.
Any liquid degradation
products which may be ,
formed in aluminum chloride pickup chamber l9
are’ removed from the system through line 22,
controlled by valve 23. Whereas the per cent of
isobutane found in the product prior to the introl
duction of further quantities of aluminum chlo 55
ride vapor into the catalyst mass was about 30%,
ment in each instance being of suf?cient duration
to effect a substantial restoration of the activity
of the catalyst.
'
4. A process for isomerizing a normal para?in
having at least four carbon atoms which com
prises continuously feeding said paraffin in ad
mixture with a promotional amount of hydrogen
halide into a reaction vessel containing a catalyst
comprising a porous support carrying an alumi
num halide and maintained under suitable isom
erization reaction conditions, continuously with—
drawing a product from said reaction vessel, con
tinuing this operation until the activity of the
aluminum halide catalyst falls substantially be
low the desired level, replacing the hydrogen hal
2000 pounds the conversion immediately returned
to about 45% and continued so for an inde?nite 60 ide in the feed stock with anhydrous aluminum
halide vapors without substantially altering the
period even though the reactor temperature was
conditions in the reaction vessel, continuing the
lower after catalyst reactivation than it was be
changed feed until the activity of the catalyst is
fore reactivation.
restored to a substantial degree and then re~
Having now thus fully described and illustrated
the nature and character of the invention, what 65 placing aluminum halide in the feed by hydrogen
is desired to be secured by Letters Patent is:
halide.
WILLIAM B. FRANKLIN.
1. A process which comprises continuously
after the introduction of the aluminum chloride
vapors in the amount of between about 1000 and
isomerizing normal para?in of at least four car
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