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2,436,484
Patented Feb. 24,’ 1948
UNITED spares- PATENT OFFICE
2,436,484
ISOMERIZATION OF SATURATED
HYDROCARBONS
Herman Pines, Chicago, 111., assignor to Universal
Oil Products Company, Chicago, 111., a corpora
tion oi‘ vDelaware
No Drawing. Application March 28, 1946,
Serial No. 657,905
9 Claims. (Cl.
260-6835)
'
2
1
?culties which are inherent in the use of hy
This invention relates to the catalytic isomer
ization of isomerizable saturated hydrocarbons
drogen.
In one embodiment, the invention comprises a
and is more speci?cally concerned with an im
proved process wherein these hydrocarbons are
isomerized under carefully selected conditions of
operation in the presence of certain partially hy
process for isomerizing a saturated hydrogen by
contacting said hydrocarbon with an isomerizing
catalyst under isomerization conditions in the
drogenated polynuclear aromatic hydrocarbons.
presence of a relatively minor amount of a par
Moreover, these isomerized products, especially
aromatic hydrocarbon,
I have discovered that the addition of these
tially hydrogenated polynuclear aromatic hydro
The isomerization of saturated hydrocarbons
carbon.
has assumed considerable importance at the pres
In a more speci?c embodiment the invention
ent time, particularly the isomerization of nor 10
consists of an isomerization- process which com
mally liquid para?inic hydrocarbons such as pen
prises contacting a normally liquid paraffin hy
tane, hexanes, heptanes, etc., which upon isomer
drocarbon with a Friedel-Crafts type isomerizing
ization produce compounds which have very de
catalyst under isomerizing conditions and in the
sirable antiknock properties when included in
aviation gasoline blends and other motor fuels. 15 presence of a partially hydrogenated polynuclear
the isomers having at least one tertiary carbon
partially hydrogenated polynuclear aromatic _hy
drocarbons selectively suppresses the decomposi
atom per molecule, may be alkylated with an
alkylating agent such as an ole?n, alcohol, etc.,
to produce higher molecular weight alkyl deriva 20 tion reactions and permits the isomerization of
the saturated hydrocarbons with a high degree
tives which have very desirable antiknock quali
ties and which are useful intermediates in organic
of e?iciency and low catalyst consumption. The
exact mechanism by which the polynuclear aro
matics suppress decomposition reactions is not
It is well known that saturated hydrocarbons
may be isomerized using catalysts oi the Friedel 25 thoroughly understood, but it Will be evident from
the experimental data hereinafter presented that
Crafts type such as aluminum halides, zinc
greatly improved results are obtained when these
halides, zirconium halides, or mixtures thereof in
hydrocarbons are present.
the presence of a hydrogen halide. The primary
The hydrocarbons which may be employed to
operating di?iculty accompanying these isomer
ization operations is the tendency toward high 30 suppress decomposition reactions during the
isomerization of saturated hydrocarbons com
catalyst consumption due to the formation of
synthesis.
'
prise broadly those hydrocarbons containing at
metal halide-hydrocarbon complexes. The cata
lyst complexes or sludges are formed by the inter
action of the metal halide with the products of
decomposition reactions which occur simulta
neously with the isomerization reaction.
least one partially hydrogenated polynuclear aro- v
matic group.
35
Various methods have been proposed to prevent
the decomposition of the saturated hydrocarbons
thereby preventing high catalyst consumptions.
For example, it has been proposed to introduce 40
hydrogen into thereaction zone to suppress de
composition and presumably to hydrogenate un
saturated hydrocarbon fragments formed by de
composition of the charging stock. The use of
hydrogen as a decomposition suppressor has been
found to be very expensive and entails the use of
a considerable amount of auxiliary equipment
such as compressors, separators, etc., to provide
a means for recycling the hydrogen to the reac
tion zone.
It is an object of the present invention to pro
vide a method for suppressing the decomposition
of the isomerizable hydrocarbons which is eco
nomical and practical and which obviates the dif
Examples of these compounds are tetralin, hy
drindene, di- and octahydroanthracene, and di
and octahydrophenanthrene. Alkyl and aryl de
rivatives of these and similar compounds also may
be employed.
The various partially hydrogenated polynuclear
aromatics are not necessarily equivalent in their
effectiveness since obviously different amounts of
suppressor may be required dependent upon the
nature of the catalyst and charging stock and
45 also upon the operating conditions employed.
The concentration of the suppressor in the isom
erizatien charging stock is generally from about
9.1% to about 5% by weight. The use of the
above mentioned partially hydrogenated aro
50 matic hydrocarbons to suppress decomposition
reactions is particularly applicable to the isomer
ization of normal pentane and normal hexane
because these particular hydrocarbons exhibit an
unusual tendency to undergo decomposition when
55 subjected to isomerizing conditions. The various
2,436,484
4
partially hydrogenated polynuclear aromatics are
separated from the isomerization reaction prod
tended that these examples unduly limit the gen
erally broad scope of this invention.
ucts by fractionation or other suitable means and
may be recycled to the isomerization step.
The operating conditions or the isomerization
vestigate the effect of tetralin and dihydroan
A series of experiments was conducted to in
thracene in the normal pentane isomerization re
process such as temperature and pressure will
action. An electrically heated autoclave equipped
vary somewhat depending upon the charge stock
with a mechanical stirrer was charged with 85
grams of normal pentane and the designated
and catalyst employed. Ordinarily, temperatures
within the range of about 50° F. to about 350° F.
amount of aromatic, and anhydrous aluminum
and more preferably within the range of from 1. chloride and hydrogen chloride were added. The
about 120° F. to about 250° F. and pressures vary
autoclave was sealed and the reaction was carried
ing from substantially atmospheric to about 500
out for a period of six hours. A blank run was
pounds per square inch or more are desirable.
also made without the addition of an aromatic
Any of the isomerization catalysts, such as
to suppress decomposition reactions. The perti
boron tri?uoride-hydrogen ?uoride-nickel, the ll nent data from these tests are tabulated as fol
reaction product of aluminum chloride and phos
lows:
phoric acid, and the like, may be employed but
the preferred isomerization catalysts are those
Run No
of the Friedel-Crafts type. In the following dis
cussion it is to be understood that the term cata 29 Charge, grams:
lyst means those of the Friedel-Crafts type. It
Aluminum chloride _______________________ __
Hydrogen chloride _____________ -_
is desirable that a hydrogen halide such’ as hy
drogen chloride and hydrogen bromide be used
Dihydroanthracene
in conjunction with these catalytic materials.
Temperature, 0C. ____
__
age
The ordinary concentration of the hydrogen 25 Maximum pressure, p
Time, hours ................. __
halide is within the range of about i to about 49
Analysis of product, Mol percent:
mol per cent of the charge and preferably from
i-Butane _________________________________ -_
n-But-one.
about 5 to about 20 mol per cent. The preferred
i-Pentane__._
n-Pcntane.__
catalysts comprise the chlorides and bromides of
n-Pcntane ______________________ __
Tetraliu .......... ..
aluminum, zinc, zirconium, and iron, either alone 30
or in admixture with one another.
1
l
@0 0nd
Bennie and highs
These cata
lysts may be employed in the solid granular state
or upon inert supporting materials such as alu
mina, silica, thoria, crushed ?rebrick, quartz, ac
tivated clays, and activated chars.
It is also within the scope of this invention to‘
employ mixtures of these compounds and in par
ticular the aluminum halides with the halides of
antimony, bismuth, and arsenic, to form catalyst
In run 1, which was the blank run, it will be
noted that although 19.2% isopentane was ob
tained there was also a total butane production
of 62.2% which represents a relatively low e?i
ciency of conversion to isopentane. In run 2 em
ploying tetralin, 52.4% isopentane was obtained
with only 8.7% of butane thus indicating the
marked effect of tetralin in suppressing decompo
composites which are molten under the conditions 40 sition reactions. It will also be noted in run 2
of operation.
that 35.1% of unconverted normal pentane was
. The isomerization operation may be conducted
recovered which could be recycled for further
in various ways. For example, the heated hydro
conversion in a continuous method of operation.
carbon charge, which may be a naphthene but
In run 3, dihydroanthracene was employed.
which is preferably a normal parailin, containing 45 Comparing the results of this test with the re
the added partially hydrogenated polynuclear arc
sults obtained in run 1, it will be noted that the
matic, may be passed either in the liquid, vapor,
or mixed phase through a reaction zone contain
ing a bed of solid granular catalyst either sup
presence of the dihydroanthracene suppressed the
butane production to a very marked extent and
resulted in a high yield of isopentane.
~
ported or unsupported, and the reaction product 50
I claim as my invention:
may be separated into the desired isomers and
1. An isomerization process which comprises
unconverted material and the latter recycled to
contacting an isomerizable saturated hydrocarbon
the reaction zone.
under isomerizing conditions with an isomerizing
Another method of operation consists of em
catalyst in the presence of a relatively minor
ploying a catalyst supply chamber containing 55 amount of a partially hydrogenated polynuclear
a bed of granular catalyst through which a stream
aromatic hydrocarbon.
of the charge is passed in liquid phase to dissolve
2. An isomerization process which comprises
the required amount of catalyst. This catalyst»
contacting a paraf?n with a Friedel-Crafts type
containing stream is introduced into a reaction
isomerizing catalyst under isomerizing conditions
zone along with a regulated amount of the hydro
and in the presence of a partially hydrogenated
gen halide, and a substantial portion of the hy
polynuclear aromatic hydrocarbon.
drocarbon is isomerized therein. This reaction
3. An isomerization process which comprises
zone may comprise a large vessel which will pro
contacting a normally liquid para?in with a
vide su?icient time for the reaction to occur or
Friedel-Crafts type isomerizing catalyst under
it may be ?lled with a retaining material, such 65 isomerizing conditions and in the presence of a
as molten salts, hydrocarbon-metal halide com
partially hydrogenated polynuclear aromatic hy
plexes, or solid packing materials such as bauxite,
drocarbon.
4, An isomerization process which comprises
other materials well known to those skilled in
contacting a normally liquid parai?n hydrocarbon
the art.
70 with a metal halide of the Friedel-Crafts type
The following examples illustrate in a general
and a hydrogen halide under isomerizing condi
way the effectiveness of the partially hydrogenated
tions in the presence of a partially hydrogenated
polyn-uclear aromatic hydrocarbons disclosed
polynuclear aromatic hydrocarbon.
herein in suppressing decomposition reactions
5. An isomerization process which comprises
during the isomerization operation. It is not in 75 contacting a normally liquid para?‘in with alu
Raschig rings, berl saddles, granular quartz and
2,436,484
5
minum chloride and hydrogen chloride under
9. An isomerization‘ process which comprises
isomerizing conditions and in the presence of a
contacting n-hexane with aluminum chloride and
hydrogen chloride under isomerizing conditions
partially hydrogenated polynuclear aromatic hy
and in the presence of a partially hydrogenated
6. The process of claim 2 further characterized 5 polynuclear aromatic hydrocarbon.
HERMAN PINES.
in that said partially hydrogenated polynuclear
drocarloon.
aromatic hydrocarbon comprises a partially hy
REFERENCES CITED
The following references are of record in the
in that said partially hydrogenated polynuclear 10 ?le of this patent:
hydrocarbon comprises a partially hydrogenated
UNITED STATES PATENTS
anthracene.
8. An isomerization process which comprises
Number ,
Name
Date
contacting n-pentane with aluminum chloride
2,382,815
Sutton et a1 _______ _- Aug. 14, 1945
and hydrogen chloride under isomerizing condi 15 2,404,436
Crawford et a1. .'_____ July 23, 1946
tions and in the presence of a partially hydro
2,406,967
Pines ____________ __ Sept. 3, 1946
drogenated naphthalene.
7. The process of claim 2 further characterized
genated polynucleararomatic hydrocarbon,
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