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Патент USA US2406868

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Patented Sept. 3, 1946
2,406,868
UNITED sTaTEsPATENT ornce
_ 2,406,868
' ~ New ISOMERIZATION rnoosss
Carl_0. 'vl‘ongberg, _West?eld, and Homer J. Hall.
Roselle, N. .L, asslgnors to Standard Oil De
velopment Company, a corporation oi’ Delaware
No Drawing. Application August 15, 1941,
~
Serial No. 407,008
'
'
‘7
13 Claims. (Cl. zoo-e835)
1
1
,
.
2
,
ess employing novel catalyst promoter to accom
containing a very small amount of cycle propane
or cyclo butane or their alkyl derivatives such
as methylcyclopropane, dimethylcyclopropane,
branched chain para?lns.
with aluminum chloride and one of the conven
This invention relates to the isomerization of
paramnic hydrocarbons by means of a novel proc
ethylcyclopropane', methylcyclobutane, dimethyl
plish the production of iso- or branched'chain
para?ins from either straight chain or less‘ 5 cyclobutane and ethylcyclobutane is isomerized
_
-
The preferred process resides in the isomeriza-
tional ‘promoters, the activity of the catalyst is
tion of normal para?lns to isop'ara?ins using at
materially increased over and above that which
least one aluminum halide as the catalyst with
would ordinarily be expected in the absence of
or without the‘ presence of the usual promoters 10 such naphthenes or \cyclo aliphatic hydrocarbons.‘
The exact nature of the. mechanism of the reac
therefor. These promoters may be free halogens,
tion which results in the increased life of the cat
for example chlorine or bromine, the hydrogen _
alyst is not de?nitely known. However, it is
halides, for example hydrogen chloride or hydro
thought that the naphthenes ortheir degradation
gen bromide, the alkyl halides, such as, for ex
ample, methyl, ethyl, propyl', butyl,_ amyl, chlo
rides or bromides, the alkyl polyhalides, such as,
for example, chloroform and carbon tetrachloride,
and the like.‘ Water may also be employed as a
promoter. It has been customary, in the past, to
subject various types of feed stocks predominat
ing in straight chain .para?inic hydrocarbons,
particularly of the butane and pentane feeds,‘ to
isomerization reactions in order to increase the '
15
products produced in the reaction zone combine
in some manner with the aluminum chloride to
produce a complex therewith which, in effect, is
the real catalyst for the reaction or which acti
vates secondarily the aluminum chloride in its
20 isomerizing activity of the normal pentane feed
stock.
I
'
Not only may the reaction be carried out with
a feed stock containing the heretofore mentioned
naphthenes in small amounts, but as a further
available quantities ‘of isobutane and isopentane.
However, one of the difficulties encountered in the 25 modi?cation of the invention, once the catalytic
isomerization of normal para?lns containing at
least 4 carbon atoms per molecule with aluminum
chloride, for example, and hydrogen chloride as a
promoter, is‘ the fact that catalyst life is not as
activity of the fresh aluminum chloride has been
enhanced by treatment with the naphthene-con
taining feed stock, the feed stock may be changed \
in a continuous process from the naphthene-con
great - as desired in commercial operation. It 30 taining feed to one free of naphthenes and com
posed essentially of the straight chain para?ln or
has been found that in the ordinary commercial
of the straight chain para?in admixed with small
continuous unit for isomerizing, for example nor
amounts of other para?inic hydrocarbons without
mal butane to isobutane in the presence of alu
the resultant usual loss of catalytic activity of the
- minum chloride and hydrogen chloride, that the
catalytic activity of the aluminum chloride, al 35 aluminum chloride which has been so treated.
'In other words, once the aluminum chloride has
though quite satisfactory at the beginning of its
been contacted with a naphthene-containing feed a
use, is found to be too rapidly degraded to the
stock, its effective catalyst life thereafter has now
point where the loss of activity for isomerizing
been found to be materially increased even though‘
requires that it be discarded and replaced by
the feed stock which is employed thereafter con
fresh aluminum chloride. This degradation and
tains no naphthenes.
'
'
loss of activity was thought to be as a result of
As a further embodiment of the invention, it is
the building up of contaminants on the surface‘
contemplated to carry out a continuous commer
of the catalyst, thereby reducing the effective
cial operation in either liquid phase or vapor
contact surface of the catalyst and also to the -»
building up of undesirable complexes between 45 phase with or without the presence of elemental
or free hydrogen ‘wherein the catalyst during its
the hydrocarbons and their degradation products
with the aluminum chloride.
‘
It now has been discovered that the effective
catalyst life of the aluminum chloride can be un
expectedly increased in these commercial opera
tions if the normal paraf?n feed stock contacted
with the freshly introduced aluminum chloride
contains‘small amounts of the 3 and 4 carbon
atom naphthenes.
By so conducting an isomeri-
zation reaction, for example if normal pentane
entire useful life has alternately contacted there
with a feed stock containing normal para?lns of
at least 4 carbon atoms per molecule and small
50 amounts of the 3 and 4 carbon atom naphthenes
and a naphthene-free para?lnic feed stock con
taining at least 4 carbon atoms and predominant
ly of straight chain con?guration though not nec
‘ essarily predominating in the same para?ln as
65 contained in the ?rst mentioned feed stock. The
"
3
2,406,868
alternate use of these two types of the feed stocks
may be so adjusted as to considerably lengthen
the catalyst life, and to thereby effectuate an in
creased yield of desired isomeric products per
pound of aluminum chloride employed in the al
4
feeds as ?eld butane are likewise desirable.
Mix
tures of one or more of these heretofore men
tioned straight chain para?inic hydrocarbons .are
likewise useful in the process, and mixtures which
contain' substantial amounts of normal parafiins
in conjunction with other paraflins are also suit
able for use in the present process. As hereto
spective feed stocks being contacted with‘ the
fore mentioned these materials as produced from
catalyts alternately as heretofore described will
petroleum may contain C3 or C4 naphthenes.
be disclosed in greater detail hereinafter.
It has been found that the naphthenes, cyclo 10 These naphthenes can be removed to give a
kylation reaction.
The periods of time of the re
propane and cyclobutane and their alkyl deriv
atives are ‘equally e?icacious in the practice of
the present invention regardless of their source
of supply. Thus, it is possible to employ as a .
naphthene-free feed stock by treatment with con
centrated sulfuric acid, halosulfonic acids such
as ?uoro- or chlorosulfonic acid, fresh or par
tially spent AlCla or by hydrogenation. '
feed stock for the process, a substantially pure
The amount of napthenes added to the alu
acyclic paraf?nic hydrocarbon mixture the con
stituents of which predominate in straight chain
minum chloride catalyst should preferably be
between about 0.10 and about 4% in the ordinary
paraf?ns of at least 4 carbon atoms per mole
operation of the process. As previously men
cule and to intermittently add from extraneous
tioned, if a greater concentration of naphthene
sources materials comprising substantially pure 20 is present, the catalyst becomes over-active too
cyclopropane and/or cyclobutane, or materials
quickly and, as a result, causes excessive degra
containing predominant para?inic acyclic hydro
dation of the norma] paraf?ns undergoing, isom
carbons but containing, also, small amounts of
erization'. When the catalyst has absorbed a
the desired naphthenes. As a further modi?ca
quantity of naphthenes su?icient to bring its ac
tion of this alternative process, it is possible to
operate on a feed stock of, for example, normal
butane or normal pentane, and to intermittently,
as the activity of the catalyst would indicate,
change to a similar hydrocarbon mixture contain
tivity to‘ the desired level the addition of naph
thenes can be discontinued until such time as
the catalyst activity materially decreases when
used in the isomerization of a naphthene-free
normal para?ln of at least 4 carbon atoms.
ing the desired naphthenes.
Superatmospheric pressure is customarily em
30
Among the naphthene-containing feed stocks
ployed in order to‘maintain a liquid phase oper
found in the oil re?ning industry may be men
ation, although it is to be distinctly understood
tioned the condensation of natural gas to produce
that vapor phase operations are likewise con
casinghead gasoline which is distilled to yield a
templated in connection with the present inven
C5 paraf?n cut, followed by the separation of the 35 tion. The superatmospheric pressures may be
normal para?ins from the isopara?ins in the C5
imposed su?icientto maintain a liquid phase op
cut, and the use of the normal pentane cut as a
eration under the reaction conditions obtained,
feed stock in the present process. This stock
and it may also be desired to'use pressures up
ordinarily will contain traces of alkyl derivatives
to as high as 1000 ‘lbs/sq. in. when operating in
of cyclopropane, cyclobutane, and/or its alkyl de 40 either liquid or vapor phase. These pressures
rivatives. This source of the naphthenes may
are designed to suppress the tendency toward
be employed exclusively as the feed stock for a
cracking, the degradation of the hydrocarbons
limited time or as a blending or addition agent
treated, particularly where the hydrocarbons
to the naphthene-free feed stock ordinarily em
ployed in the manner heretofore indicated. An
other suitable source of supply of feed stocks
which are found to contain the desired'naph
thenes may be obtained by the distillation of
either parafllnic or preferably naphthenic crude
treated are of higher molecular weights, for ex
. and which contains the desired naphthenes as a
ity of the catalyst, thereby resulting in excessive
degradation of the feed stock, molecular hydro
ample, the hexanes and heptanes and to give
increased contact times and throughputs. 'I'he
pressures may be obtained partially by the use
of the halogen-containing promoters heretofore
mentioned, or they may be also attained by the
oils to obtain a C5 fraction, followed by the seg 50 introduction of free or molecular hydrogen either
regation of the normal pentane from the isopen
alone or in conjunction with the halogen-con
tane and the use of this normal pentane fraction,
taining promoters. To prevent excessive activ
feed stock for the reaction. Straight run naph
thas with or without small amounts of naph
thenes contained therein may also be employed
as feed stocks and sources of naphthenes in the
present process.
Of course, as heretofore mentioned, naphthenes
prepared synthetically, or obtained from other
gen has been found to be particularly effective.
The reaction conditions are those customarily
employed when carrying out para?inic isomeri
ployed, if desired, in conjunction with feed stocks
zation reactions in the presence of aluminum
chloride or aluminum bromide. The quantity of
catalyst may be varied between about 1 and
about 150% by weight based on the para?in
maintained in the reaction zone at any one time.
which do not contain the requisite amounts of _
In vapor phase operation the amount of catalyst
sources in more or less pure form may be em
naphthenes. The heretofore mentioned sources
may be much higher. Optimum catalyst con
of normal pentane which naturally contain the 65 centrations vary depending upon the other re
desired naphthenes may be used in varying
action conditions maintained. Preferably a
amounts and for varied lengths of time, depend
ing to a large extent upon the amount of the C:
catalyst concentration between about 15. and
about 70% by weight is sufficient in liquid phase
and/or C4 naphthenes ‘contained therein.
operation. Likewise, the amount of promoter
When it is desired to operate with a feed stock 70 employed, may vary considerably, for example,
substantially free of the heretofore discussed
between about.2 and about 24% by weight of
naphthenes, the ordinary feeds may be employed.
the hydrocarbon present in the reaction zone at
Thus, for example, normal butane, normal pen
any one time but preferably it is maintained be
tane, normal hexane, normal heptane, and the
tween about 4 and about‘10%. The tempera
higher homologues, may be employed. Such 75 ture of the reaction zone is maintained depend
2,400,808
5",
moval from the isomerization reactor or reactors
is well known in the art and generally embodies
the stripping of the promoter from the reacted
erably between about 100 and about 225° F; for
mixture followed by the removal of any residual
liquid phase operation. In vapor phase opera
tion the temperature oflthe reaction zone may be . 5 amounts of aluminum chloride or aluminum chlo
ride complex, as the case may be, and the semi
maintained at between about 150° F. and about
ration of the‘ 'unreacted- portion of the reacted
500° F. preferably between about 275 and about
' mixture-from the isomeric products produced ~
375° F. These temperatures are customarily
in the reaction by convenient means such as,
employed with normal butane isomeriz'ation re
actions. However, in ‘the case of normal pe'n- 10 for example, fractionation together with the re
cycle of the promoter to the isomerizatlon reac
tane, a somewhat less drastic temperature con
tors with the optional recycle of unreacted re
dition is customarily employed. However, in the
actants as well.
,
present case, where it may be desirable to em
As one mode of carrying out the invention, a
ploy a C5 feed stock when contacting the cata
lyst with naphthenes and a C4 feed stock when 15 feed stock of normal pentane with and without "
traces of naphthenes will be described. A feed
contacting the naphthene activated catalyst
with isomerizing reactants, the temperatures ~ stock containing no naphthenes and composed
predominantly of normal pentane under a given
“ may vary as between the various types of feed
set of reaction conditions with aluminum chlo
stocks so as to maintain optimum reaction con
ditions for each type of feed stock. On the other 20 ride and promoter will give a 50% conversion of
normal pentane to isopentane. Under similar .
hand, the reaction conditions may be maintained
conditions, wherein the normal pentane contains
constant, regardless of the feed stock employed
from one-tenth'to 1% of naphthenes, particue
except that the time of contact may be varied
' ent, of course, upon the other reaction conditions,
usually between about to and about 300° F., pref
to suit the particular feed stock.
Thus, for ex-
_ ' larly cyclopropane and/ or cyclobutane, a conver
ample, if the catalyst zone is maintained at a 25 sion of about 75% of the normal pentane con
tacting the catalyst will be attained with a grad-- - '
temperature of 75°F. and it is desired'to have
ual increase in catalyst activity to the point where
the temperature maintainedregardless of the
excessive degradation of the'normal C5 feed will
feed stock, the treatment of the catalyst with a
occur. In operating the process, andin'order
naphthene-containing feed stock,‘ for example, a
C5 normal pentane containing something like 30 to maintain the activity of the catalyst, one of
two possible courses of action are .desirable.
1% or less of Ca. and C4 naphthenes, may be con
When the catalyst activity becomesexcessive with
‘tacted at the rate of between about 1 or 2 hours
normal pentane, the feed stock may then be
until the catalyst activity is such that further
shifted to a normal butane isomerization in which
treatment with this feed stock will result'in ex
cessive degradation of the normal pentane. At 35 no naphthenes are contained, in which case the
over activity of the catalyst is, to some extent,
the end of this time, the temperature and
alleviated by the fact, that normal butane is more
amount of catalyst is allowed to remain the same
di?icult to isomerize than normal pentane, or the
and a naphthene-free feed stock, say, for exam
catalyst may be contacted under the same or
ple, normal butane, is contacted under the same
reaction conditions except that the time of rest-"40 milder conditions with normal pentane substan
tially free of naphthenes for such a length of
dence of the normal butane in contact with the
time that the conversion governed, of course, by
aluminum chloride may be somewhat lengthened,
the catalytic activity, drops to, say 30 or 40%
say to 2 or 3 hours, dependent upon the activity _
of the particular catalyst mass. Ordinarily, the . depending upon the desired economical opera’
time of- contact will be between about 0.1 and 45 tion of the process. It should be understood, of
,course, that ii the activity level of the catalyst is
about 20 hours, usually between about 2 and
not of any economical importance, the conver
about 10 hours, for liquid phase operation and
sion may be dropped to 20 or 25% or even lower,
between about 15 seconds and about 15 minutes
if desired. Once the catalyst activity has dropped
preferably between about 20 seconds and about 3
minutes for vapor Operation depending, of 50 to this point, it may be restored to somewhere
near the original activity by re-feeding thenaph
course, as heretofore mentioned,‘ upon the other
theme-containing normal pentane until the ac
reaction conditions.
tivity has once again risen to somewhere around
A number of ‘reactors may be employed in se
a conversion of ‘75%. This procedure as described
ries or in parallel so that the feed stocks may be
interchangeably fed to the various reactors so 55 may be repeated until the catalytic activity is no
longer capable of being restored, in which’case
that while one catalyst mass is undergoing treat
the catalyst is discarded and new catalyst em
ment with a naphthene-containing feed, another
which has been activated in this manner may be ‘
ployed.
-
Where it is desirable to accurately control the
taining no naphthenes. ,A differential in reac- no amount of naphthenes entering into contact with
the aluminum chloride, it may be advantageous
tion conditions to suit the optimum isomerizing
to remove all naphthenes from the feed stock .
activity of the particular feed stock may con
and introduce controlled amounts thereof for a
veniently be maintained where a plurality of re
better control of the catalyst activity. In order
actors is employed where such could not be
readily accomplished in a commercial operation 65 to remove the naphthenes from a normal par
a?in containing at least 4 carbon atoms‘ per
if a single reactor were employed. Mechanical
molecule, treatment with such compounds as
means for agitating the contents of the reactors
concentrated sulfuric acid, ?uor and chlor sul
when liquid phase operation is employed may be
fonic acids, and the like, are found to e?ectively
by such devices as motor driven propellers, jets ,
of restricted internal diameter, turbo mixers, and 70 remove the naphthenes
As illustrative of the increased activity of thev
the like. A percolation of the liquid feed stock
catalyst when employing small amounts of naph
through a bed of solid catalyst may also be em
thenes, theiollowing example is presented al
ployed. Likewise for vapor phase operation, a
though it is obviously not- intended that the in
bed of catalyst is employed.
.
The treatment of the reacted mixture upon re- 75 vention be limited thereto.
activating the isomerization of a feed stock con
2,406,868
7
Example
action conditions and in the presence of a small
amount or at least one naphthene taken from the
A shaking bomb of 500 cc. capacity was charged
with 150 grams of substantially pure normal
group consisting of cyclopropane, cyclobutane '
normal conversion of a n-pentane feed using
group consisting of cyclopropane, cyclobutane,
and alkyl derivatives thereof, said three- and
pentane, about 150 grams of aluminum chloride, 5 four-membered ring naphthenes being substan
2.25 grams of cyclopropane, and between about
tially the only naphthenes present.
3 and about 4% of hydrogen chloride. The mix
8. A process as in claim 7 wherein the naph
ture was heated to a temperature of about 78°
thene is present in an amount between about
and shaken for about3 hours, at the end of
0.1 and about 4% by weight of the feed.
which time the reacted product was foundto con 10
9. A process which comprises isomerizing a
tain isopentane to the extent that about 73%
normal para?in containing at least 4 carbon
of the normal pentane had been converted. Un
atoms per molecule substantially free of naph
der similar conditions, using fresh aluminum
thenes under isomerizing reaction conditions in
chloride but in which no cyclopropane was pre
the presence or a promoter and a catalyst mass
sent, the normal pentane reacted to the extent 15 formed by treating aluminum chloride under iso
of only about 44%.
merization reaction conditions with a feed stock
'As an example of the promotional eifect of
containing small amounts of at least one low
naphthenes present in paraf?nic feed stocks, the
molecular weight naphthene taken from the
100% AlCh, 22% HCl, a temperature of 75° F., 20 and alkyl derivatives thereof and discontinuing
with 2 hours shaking is about 75% whereas when
the treatment prior to the activity of the catalyst
the naphthenes present are removed by pretreat
becoming such as to cause excessive degradation
ing the feed with sulfuric acid, fiuor- or chloro
of normal paraf?ns containing at least 4 carbon
sulfonic acid or by hydrogenation treatment only
atoms per molecule under isomerization reaction
44%, 50%, 51% and 48% conversion respectively 25 conditions.
is obtained.
Having now thus fully described and illus
10. The process as in claim 9 wherein nor
mal pentane is employed as the feed stock.
trated the character of the invention, what is
11. The process as in claim 9 wherein super
claimed as ‘new and useful and desired to be
atmospheric pressure is maintained by intro
secured by Letters Patent is:
80 ducing molecular hydrogen.
1. A process which comprises contacting at
12. A process which comprises contacting a
least one normal para?in containing at least 4
normal para?in containing at least 4 carbon
carbon atoms per molecule in the presence of
atoms per molecule under isomerizatlon reaction
an aluminum halide under isomerization reac
conditions in the presence of a small amount of
tion conditions and in the presence of a halogen 85 a low molecular weight naphthene taken from
containing promoter and a small amount of a
the group consisting of cyclopropane, cyclobu
naphthene taken from the group consisting of
tane, and alkyl derivatives thereof, a promoter,
cyclopropane, cyclobutane and alkyl derivatives
thereof, said three- and four-membered ring
and an aluminum halide followed by the con
tacting of the resulting catalyst mass with a
naphthenes being substantially the only naph
thenes present.
naphthene-free feed stock comprising essential
ly at least one normal para?in containing at
,
2. A process which comprises. carrying out a
process as ‘in claim 1 wherein superatmospheric
pressure is maintained by the use of molecular
hydrogen.
least 4 carbon atoms under lsomerization reac
tion conditions and in the presence of a pro
moter.
45 13. A process as in claim 12 wherein a, con
tinuous process is carried out in which the cata
3. A process as in claim‘ 1 wherein the naph
thene is present in an amount between about 0.1
lyst is contacted alternately with a naphthene
and about 4% by weight of the feed.
containing feed stock and a naphthene-free feed '
4. A process which comprises contacting at
stock.
least one normal paraffin containing at least 4 50 14. A process which comprises contacting nor
carbon atoms per molecule in the presence of
mal pentane containing at least one naphthene
aluminum chloride under isomerization reaction
taken from the group consisting of cyclopropane,
cyclobutane and alkyl derivatives thereof with
aluminum chloride in the presence of hydrogen
conditions and in the presence of at least one
hydrogen halide and a small amount of a naph- .
thehe taken from the group consisting of cyclo
propane, cyclobutane and alkyl derivatives there
of, said three- and four-membered ring naph
thenes being substantially the only naphthenes
present.
55 chloride under isomerization reaction conditions
for a period of time only suflicient to maintain
about a 75% conversion of the normal pentane
to isopentane followed by contacting the catalyst
with a normal C5 paraffin hydrocarbon fraction
5. A process which comprises contacting nor 60 substantially free of naphthenes under isomeri
mal pentane in the presence of aluminum chlo
zation reaction conditions and in the presence
ride and hydrogen chloride under isomerizing. of hydrogen chloride and recovering isopentane.
reaction conditions while maintaining in the re
15. A process as in claim 14 wherein the naph
action zone a small amount of at least one naph
thene-free feed stock comprises ?eld butane.
thene taken from the group consisting of cyclo 65 16. A process which comprises contacting con
propane, cyclobutane and alkyl derivatives
tinuously aluminum chloride under isomerizing
thereof, said three- and four-membered ring
reaction conditions with a normal pentane feed
naphthenes being substantially the only naph—
stock containing at least one low molecular
thenes present.
weight naphthene taken from the group consist
6. A process as in claim 5 wherein the naph 70 ing of cyclopropane, cyclobutane, and alkyl de
thene is present in an amount between about
rivatives thereof until the catalytic activity has
0.1 and about 4% by weight of the feed.
7. A process which comprises contacting nor
mal butane in the presence of aluminum chlo-}
ride and hydrogen chloride under isomerizing re 75
increased to a high level followed by the treat
ment of the resultant catalyst mass with nor
mal butane substantially free of naphthenes un- '
til such time as the catalytic activity of the
“oases
'
i
-9
_
10
catalyst mass is reduced substantially and alter
superatmospheric pressure is maintained to in
nately and continuously contacting the catalytic
sure liquid phase operation. '
mass with the naphthene-containing feed and
the naphthene-free feed until the catalytic ac-‘
-
18. A process as in claim 16 in which the re
action is carried out in the vapor phase and
.tivity of the catalyst has become substantially l the catalyst mass constitutes a plurality of beds.
completely spent.
CARL O. TONGBERG.
17. A process as in claim 16 wherein sumcient v
HOMER J. HALL.
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