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Патент USA US2408140

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2,408,139
Patented Sept. 24, 1.946
UNITED STATES PATENT OFFICE’
2,408,139 ’
DEHYDROGENATION PROCESS
Carlos L. Gutzeit, Terre Haute, Ind., assignor to
Shell Development Company, a corporation of
,
Delaware
No Drawing. Application March 6, 1944,
Serial No. 525,299
7 Claims. (01. 260-680)
1
This invention relates to a new and improved
process for effecting dehydrogenations of a cer
tain type and to new and improved catalysts
therefor. More particularly the invention re
lates to a process for the production of diole?ns
by catalytic dehydrogenation characterized by the
2
' 580° C. In order. to produce the corresponding
diole?ns more or less selectively, the ole?ns
treated are therefore those which may be heated
to temperatures above about 580° C. without sub
stantial decomposition. Since the tendency for
the various ole?ns to undergo thermal cracking
increases with their molecular weights, preferred
use of special catalysts under special conditions.
ole?ns to be treated are the lower ole?ns having
A particular aspect of the invention relates to a
from 4 to about 6 non-quaternary carbon atoms
process for the production of butadiene by the
catalytic dehydrogenation of normal butylenes.
10 in a straight chain. The ole?n to be dehydro
' genated may be a single hydrocarbon or, if de
An object of the invention is to provide a proc
sired, a mixture of ole?ns may be dehydrogenated
ess whereby the dehydrogenation of mono-ole?ns
to produce a mixture of diole?ns. Also, in some
to the corresponding diole?ns and certain other
cases a single diole?n may be‘produced from a
related dehydrogenation processes, for instance
the dehydrogenation of ethyl benzene to styrene, l5 mixture of isomeric ole?ns. For example, buta
diene may be produced from either butene-l or
may be more economically carried out with good
butene-2 or a mixture of the two, and isoprene
conversions and excellent e?iciency at ordinary
may be produced from methyl ethyl ethylene, tri
or moderate pressures. Another object of the in
methyl ethylene, or isopropyl ethylene, or amix
vention is to provide new and improved catalysts
which are particularly suited for e?'ecting dehy .20 ture of these ole?ns. ‘
In order to facilitate the recovery of the di
drogenation reactions of the described type at 1
ole?n and unconverted mono-ole?n from the
elevated temperatures in the presence of steam.
product and 'for various other practical reasons,
Another object is to provide a process of the de
it is usually desirable that the feed consist essen
scribed type which maybe carried out substan
tially continuously.
25 tially of_ the desired ole?n or mixture of ole?ns.
This is, however, not essential and in some cases
In the preferred embodiment of the invention
suitable mono-ole?ns are converted more or less
it may be more advantageous to use ole?n frac
tions comprising appreciable amounts of relatively
inert diluents. Thus, for example, in the produc
. peratures above about 580° C. in the presence of 30 tion of, butadiene, a so-called butane-butylene
selectively in’ good yields to the corresponding
diolé?ns by catalytic dehydrogenation at tem
at least two mols of steam per mol of mono
ole?n with special alkalized iron oxide and/or _
fraction containing substantial amounts of bu
cobalt oxide catalysts containing minor concen
trations of bismuth oxide. The iron oxide and/or
cobalt oxide in the catalysts isin molecular excess
with respect to the total of any additional con
stituents of the catalyst which react with the iron
oxide and/or cobalt oxide under the process con
are substantially unaffected in the process of the
invention and may be considered as inert dilu
ents. In this respect the process of the invention
tane may be used.
The para?in hydrocarbons
differs fundamentally from most of the known '
dehydrogenation processes which are much more
suited for the dehydrogenation of para?ins than
for the dehydrogenation of ole?ns and are totally
ditions.
The process of the invention is particularly ad 40 incapable of selectively dehydrogenating ole?ns
in the presence of para?lns.
vantageous for the production of butadiene by
The dehydrogenation of ole?ns to the corre
‘catalytic dehydrogenation of normal butylenes
sponding diole?ns cli?ers from most other dehy
such, for instance, as the various commercial bu
drogenation processes in requiring a low partial
tylene fractions consisting essentially of butene-l
and/or butenee2. It is, however, also applicable 45 pressure of reactants in the reaction zone. Thus,
in all known processes for the production of di
and advantageous for the production of other di
ole?ns by dehydrogenation, it is necessary either
ole?ns and particularly conjugated diole?ns, such
to carry out-the dehydrogenation under a sub
as piperylene, isoprene, the various hexadienes,
, stantial vacuum or to employ large quantities of
etc., from the corresponding mono-ole?ns. Thus,
theprocess may generally be applied for the pro 50 a diluent. Operation under diminished pressure is
very costly. The use of inert diluents to decrease
duction of diole?ns from the corresponding mono
the partial pressure of the reactants usually
ole?ns having at least four non-quaternary car
makes the ei?cient separation and recovery of the
bon atoms in a straight chain. The process of
diole?n from the product very dif?cult and this
the invention involves the treatment of the ole?ns
in the vapor phase at temperatures above about 55 is a serious disadvantage. . Steam is an ideal
3
2,408,139
I
4
diluent but, unfortunately, many of the most
active dehydrogenation catalysts are not suited
for use in the presence of steam. Also, most of
the known catalysts are not suf?ciently selective
Iron oxide produced as a by-product in the pro
duction of alumina, for instance, is suitable.
Suitable iron oxide may also be produced from
certain iron ores such, for instance, as high grade
in their action and, if steam is used as a diluent,
hematite. These ores per se generally give rela~
they catalyze the oxidation of the reactants by the
tively poor catalysts.
steam, thus giving low yields.
able, however, .by grinding them and retorting
The above-described ole?ns are dehydrogenated, according to the process of the invention,
with ammonium sulfate. The ammonium sulfate
may be recovered and reused,
They may be made suit
in the presence of a substantial mol excess of 10
‘ The iron oxide is used in intimate association
steam with special catalysts which are designed
to selectively dehydrogenate ole?ns in the presence of steam over long periods of time with relatively infrequent regeneration. In the process
of the invention the use of steam is not merely 15
with minor concentrations of bismuth oxide.
Bismuth oxide, when in intimate association with
iron oxide, it appears, prevents the reduction to
below a given oxidation state which is dependent
upon the composition of the reactant feed, the
permissible; the steam besides being an ideal -
I temperature in the reaction zone, and the effec
diluent has other important functions and is es-
tive concentration of bismuth oxide. The effec~
sential. Thus, in the present process the material ~
tive concentration of bismuth oxide is a function
to be dehydrogenated is contacted with the cataof the actual concentration and the intimacy
lyst in the presence of at least two and preferably 20 of contact with the iron oxide. By the use of
at least seven mol proportions of steam. In the
suitable effective concentrations of bismuth oxide
dehydrogenation of butylene to butadiene, for
the desired most active state of oxidation of the
example, the best results have been obtained
iron oxide is stabilized and excessive reduction
when using from about 7 to 30 mols of steam per
of the iron oxide with its consequent catalyzation
mol of butylene.
25 of the formation of large amounts of carbon is
In order to use the above-speci?ed concentraprevented. In order to establish, stabilize and
tions of steam advantageously, it is necessary that
maintain the desired state of oxidation of the
the process be carried out at relatively high temiron oxide under the speci?ed conditions, concen
peratures. Thus, the dehydrogenation is carried
trations of bismuth oxide of between about 1 and
out in the present process at a temperature above 30 40 mol per cent (calculated as B1203) and prefer
about 580° C. and more generally at a temperaably between about 2 and 25 mol per cent (the
ture between about 660° C. and 700° C‘. Somebalance being iron oxide calculated as F6203) are
what higher temperatures may be used but are
indicated.
generally unnecessary.
The iron oxide and bismuth oxide may be
The above-speci?ed ole?ns are dehydrogen- 35 brought into a suitable intimate association in a
ated according to the process of the invention
variety of ways. For instance, a mixture of iron
by contacting them under the conditions set forth
and bismuth salts, for instance the nitrates, may
with special catalysts consisting essentially of
be thermally decomposed and the powdered mix
alkalized iron oxide provided with minor concenture pelleted; or the hydrous Oxides Of iron and
trations of bismuth oxide. Cobalt oxide is some- 40 bismuth may be mixed and the mixture partly
what more active than iron oxide and may be
dried and pilled or extruded; 01‘ an iron Oxide s01
substituted for part or all of the iron oxide. Howmay be mixed With bismuth oxide or may be im
ever, in view of the relatively high cost of cobalt
Dregnated With a Suitable bismuth salt decom
oxide, its practical application is probably limited
posable t0 the Oxide by heating
to use in minor concentrations. In the following 45 In the Catalyst of the invention it is essential
the catalysts are referred to as iron oxide catathat the iron oxide be alkalized with a small
lysts with the understanding that the iron oxide
amount of an alka1i. Compounds of the alkali
may, if desired, be substituted in part by its equivalent, cobalt oxide.
metals (Li, Na, K, Rb, CS) are Suitable of these,
the compounds of potassium are preferred. The
It appears that the state of oxidation and also 50 alkaline earth metals (Ca, Sr and Ba) and Copper
possibly the State of hydration of, the iron Oxide
and silver also exert a similar effect and their
are important in determining the activity of the 1
catalyst The exact states of Oxidation and hydration of the iron oxide during use of the catalyst are not known. It appears, however, that 55
Compounds may be used in Place Of part Of the
alkali metal compounds. The alkali or mixture
of alkalis may be incorporated into the catalyst
in the form of various compounds such as the
the maximum activity and selectivity of the cata-
nitrate, hydroXide, acetate, sulfate, carbonate
lyst for these particular reactions are obtained
and the like. These compounds are probably
when the iron oxide is in an intermediate state
decomposed or reduced in part to the oxides dur
of oxidation between ferrous oxide and ferrosoing the preparation and/or use of the catalyst.
ferric oxide, and is slightly hydrated. The de- 60 The concentration of alkali, calculated as the
sired States Of Oxidation and hydration, Whatever
oxide, should be at 1east0.2 mol per cent based
they may be, are established and maintained by
on the iron and bismuth oxides _(calculated as
the particular combinations and concentrations - R203) and is preferably somewhat higher for
of bismuth oxide and alkalis and the particular
instance between about 0.5 mol per cent and 5
reaction conditions. Consequently, the catalysts 65 mol percent. The alkali may be incorporated
of the inventien may be prepared from iron oxide
into the catalyst at any convenient stage of the
derived from a variety of sources. Suitable iron
preparation. In such case, however, Where the
oXldes may be Prepared, T01‘ Instance, by the
catalyst is formed into particles of a desired size
thermal decomposition of iron compounds such
by pilling, extruding or the like, the alkali is
as fernc nitrate, ferric acetate, ferrous oxalate, 70 preferably incorporated prior to the forming op~
ferric ammonium oxalate, etc. Also, very suitable
eration. During extended use of the catalyst
iron~ox1des may be produced in the wet way by
the alkali used, particularly if it is potassium
precipitation of the hydrous oxides from solumay be partly lost from the catalyst ‘by vglatjljl
tions of iron salts such as ferric nitrate, ferric
zation and this may cause a decline in the ac
sulfate and the like, followed by dehydration. 75 tivi‘ty of the catalyst. If this happens, the activ
2,408,13d
5
6
ity of the catalyst may be restored by simply
adding additional alkali, for instance by impreg
nation, or by adding a small amount of potas
in the presence of steam, and, as pointed out,
steampis essential for their use. If, during use,
they become relatively inef?cient due to lack of
sium carbonate with the steam.
su?icient steam, they may be restored to essen- '
'
tially their original activity by simply steaming
The inclusion of minor amounts of additionalv
agents in the catalyst is not precluded. For ex
them for a few hours, preferably at a tempera
ture between about 600° C. and 800° C.
ample, a small amount of barium oxide .or cop
The process of the invention may be carried
per oxide appears to exert an additional e?ect
out in a so-called dust catalyst, ?uidized cata
and may be present. However, the major active
lyst, or moving bed system. In these systems the
constituent should be the described alkalized iron
dehydrogenation may be carried out continu
oxide-bismuth oxide and any components which
ously in one reactor and if desired the catalyst
are capable of reacting with the iron oxide under
may be continuously treated to retain its effec
the process conditions, for instance to form a
spinel, if present at all, are present in minor
tiveness in a second reactor. The process can,
mol amounts with respect to the iron oxide. For 15 however, also be carried out substantially con
tinuously when simply passing the reactant va
this reason, such materials as alumina, magnesia
porsand steam through a ?xed bed of the cat
etc., if present at all, are present in minor con
centrations and cannot be used'as supports, car
alyst provided in a suitable converter, catalyst
riers 0r diluent-s.
‘
a
case, or elongated reaction tube maintained at
As is known, most catalysts’ are deactiviated or 20 the desired temperature. For the purpose of the
severely damaged if subjected to fairly high tem
present speci?cation an operation in which the
peratures. The loss of catalytic activity mayfbe
conversion and, conversion e?iciency remain
due to several factors ‘but is usually due to loss
with no appreciable drop for a period of continu
of available catalytic surface caused by sinter
ous operation of at least 10 hours under a ?xed
ing and recrystallization, or to change of the 25 set of conditions is considered to be an essen~
catalyst constituents into inactive forms, or to
tially continuous operation. Conversion is herein
chemical interaction of the catalyst constituents
de?ned as the percent of the reactant applied
with one another to form inactive materials.
which undergoes reaction and'is converted into
Few catalysts are capable of retaining their ac
a different product. Conversion e?iciency is de
tivity when subjected to temperatures above
?ned as the percent of the material converted or
about 700° C. For this reason it is the practice
reacted which is converted to the desired prod
to avoid subjecting catalysts to temperatures
uct-in this case, diole?ns having the same num
above those absolutely necessary. The catalysts
ber of carbon atoms as the parent material. The
used in the process of the invention are very
rugged and are capable of withstanding temper 35 conversion and conversion ei?ciency are inter
dependent, the conversion efficiency becoming
atures in excess of 800° C. without any loss of
lower as the conversion is increased. The opti
mum conversion and conversion ei?ciency for any
often materially improved by subjecting them
given
operation, therefore, depend upon the par—
to a drastic heat treatment. This treatment is
bene?cial in all cases but is particularly bene?cial 40 ticular economic factors. In the production of
butadiene by the present process, by way of ex
when applied to‘ catalysts which initially have
ample, conversions of about 25-30% are consid
a relatively large available surface, for instance
activity. Furthermore, it is found that they are
above about 30 square meters pergram.. Thus,
it is particularly bene?cial whenapplied to cat
ered at present to be quite suitable.
In the production of diole?ns according to the
alysts prepared from precipitated iron hydroxide
The heat treatment apparently destroys certain
q process of the invention, thecontact time of the
ole?n with the catalyst a?ording the optimum re
sults depends upon the particular ole?n or mix
extra-?ne pores in the catalyst and thereby de
ture of ole?ns being dehydrogenated and the par
creases, the available surface. Thus, although it
ticular conditions chosen, and may best be de
is not essential, it is usually desirable to calcine
the catalyst prior to use to reduce the available 50 termined for any given case by starting with a
very short contact time and then gradually in
‘surface to below about 30 square meters per
creasing ‘the contact time until the desired con
gram. The calcination may be carried out at
temperatures of from about ‘700° C. to about
version and conversion efficiency are obtained.
Suitable contact times for the dehydrogenation
'1000° C., for instance 750° C. to 900° C. In some
cases the bene?cial effect may be obtained with 55 of butylenes to butadiene, by way of example, are
of the order of 0.02 to 0.5 second. Since the true
only a short heat treatment; the time of cal
contact time is dif?cult to determine accurately,
cination is, however, not critical and rather long
it is desirable to speak in terms of gaseous hour
calcination-s, for instance 24 hours, may be em
ly space velocity (G. H. S. V.) which is de?ned
ployed without damage to the catalyst.
The catalyst may be used in any of the con 60 as the volumes of reactant gas (N. T. P.) con
tacted with a unit volume of catalyst bed per
ventional forms such as powder, pills, spheres,
hour. The process of the invention allows excel
saddles, extrudates or irregular ‘fragments of a
lent conversions todiole?ns to be obtained quite
shape and size adapted. for the reaction system
selectively over a considerable range of suitable
to be used. These catalysts, it is found, are us
ually sensitive to changes in the particle size; 65 space velocities. Applicable gaseous hourly space
velocities are, for example, between about 300
Thus, their effectiveness increases markedly with
and 3000.
decrease in size of the catalyst particles. For
The process‘, may be carried out under partial
this reason it is desirable to use the catalyst in
vacuum or under superatmospheric pressures.
the smallest size consistent with the allowable
pressure drop in the converter.
‘
,
.One of the advantages of the process is, however,
The above-described catalysts are exception
that neither vacuum nor high pressures are re
ally rugged and may be heated ‘to temperatures
quired and that excellent results may be obtained
while workingat atmospheric pressure or very
up to about 900° C. to 1000° C. in'the presence of
steam without loss of efficiency. They are par
moderate pressures, for instance pressures of
ticularly adapted for use at high temperatures " 75
from 1 to 3 atmospheres.
"
* ‘ i
' "
'
2,408,139
7
Example I
A catalyst consisting of an essentially ho
mogeneous mixture of iron oxide and bismuth
oxide (mole ratio of Fe to Bi=80:20) alkalized
with 0.5 mole per cent of potassium nitrate was
prepared as follows: The hydrous oxides of iron
8
very practical process for the production of di
ole?ns from the corresponding mono-olefins by
dehydrogenation. The dehydrogenation of ole~
?ns to the corresponding diole?ns di?ers funda
mentally from most other dehydrogenation proc
esses.
This is evident from the conditions re
quired. Thus, dehydrogenation of mono-ole?ns
to diole?ns requires a low partial pressure of re
tion of ferric sulfate and bismuth nitrate (con
actants in the reaction zone, requires very high
taining 3 moles of nitric acid per mole of bismuth
temperatures, and requires very short contact
nitrate) with ammonium hydroxide at a ?nal pH 10 times. . These drastic and unusual dehydrogena
of about 8.5. The co-precipitated hydrous oxide
tion conditions are perhaps necessitated partly
mixture was ?ltered, washed, and then mixed.
by the great polymerizing tendency of the prod
with the required amount of potassium nitrate.
uct. Since the process of the invention is par
The mixture was then dried at about 110° C. and
15 ticularly designed to selectively dehydrogenate
?nally calcined at 750° C. for 6 hours. ’
mono-ole?ns to diole?ns under these special ‘con
This catalyst after pretreating for 1 hour with
ditions, it cannot be expected to be advantageous
and bismuth were co-precipitated from a solu
a mixture of steam and hydrogen at 600° C. was
or even applicable for other types of dehydrogena
used for the continuous production of butadiene
tion reactions. An exception is, however, the pro
by catalytic dehydrogenation of a typical normal
duction of styrene and its homologues by the de
20
butylene fraction consisting essentially of butene
hydrogenation of the corresponding alkyl aro
l and butene-2. The butylene was vaporized and
matic hydrocarbons. This dehydrogenation can
preheated and passed in admixture with steam
be advantageously carried out under the condi
through a stationary bed of the catalyst. The
tions speci?ed for the production of diole?ns.
dehydrogenation conditions were as follows:
I claim as my invention:
1. A process for the continuous production of
Temperature __________________ __ About 625° C.
locity ________ __' ________________ __ About 500
butadiene from normal butylene by dehydrogen
ation which comprises continuously contacting a
Steam gaseous hourly space velocity_ About 7000
normal butylene in the presence of at least two
Butylene gaseous hourly space ve
Pressure (at exit) __ About 1 atmosphere absolute 30 mols of steam per mol of butylene at a tempera
ture above about 580° C. and at a gaseous hourly
space velocity between about 300 and 3000 with
a dehydrogenation catalyst consisting essentially
of an essentially homogeneous mixture of iron
oxide and bismuth oxide and potassium oxide
containing said iron oxide as the major constitu
butylene applied. The conversion efficiency was
ent and from 1 to 40 mol percent of bismuth oxide
therefore about 75%.
and from 0.2 to 5 mol percent of potassium oxide.
2. A process for the continuous production of
Example II
butadiene from normal butylene by dehydrogen
A catalyst consisting of an essentially ho 40 ation which comprises continuously contacting
mogeneous mixture of iron oxide and bismuth
a stream of a normal butylene in the presence
oxide (mole ratio of ‘Fe to Bi=99:1) alkalized
of from '7 to 30 mols of steam per mol of butylene
with 0.5 mole per cent of potassium nitrate was
at a temperature above about 530° C. and at a
prepared as follows: The hydrous oxides of iron
g; Cl gaseous hourly space velocity between about 300
and bismuth were'co-precipitated from a solu
and 3000 with a dehydrogenation catalyst con
tion of ferric sulfate and bismuth nitrate (con
sisting essentially of an essentially homogeneous
taining 3 moles of nitric acid per mole of bismuth
mixture of iron oxide, bismuth oxide and potas
nitrate) with ammonium hydroxide at a ?nal pH
sium oxide, containing said iron oxide as the
of about 8.5. The co-precipitated hydrous oxide
major constituent and from 1 to 40 mol percent
mixture was ?ltered, washed, and then mixed
of bismuth oxide and from 0.2 to 5 mol percent of
with the required amount of potassium nitrate.
potassium oxide.
The mixture was then dried at about 110° C. and
3. A process for the continuous production of
?nally calcined at 750° C. for 6 hours.
butadiene from normal butylene by dehydrogen
This catalyst after pretreating for 1 hour with
ation which comprises continuously contacting
The operation was carried out continuously.
The conversion of normal butylene to butadiene
increased during the ?rst 12 hours of operation
to about 25% and showed no signs of decline. The
amount of butylene reacted was about 33% of the
a mixture of steam and hydrogen at 600° C. was
a normal butylene in the presence of at least two
mols of steam per mol of butylene at a tempera
ture above about 580° C. and at a gaseous hourly
space velocity between about 300 and 3000 with
used for the continuous production of butadiene
by catalytic dehydrogenation of a typical nor
mal butylene fraction consisting essentially of
butene-l and butene~2.
The butylene was va
a dehydrogenation catalyst consisting essentially
porized and preheated and passed in admixture
of an essentially homogeneous mixture of iron
with steam through a stationary bed of the cat
alyst. The dehydrogenation conditions were as
follows:
oxide, bismuth oxide and potassium oxide, con
taining said iron oxide as the major constituent,
.
a minor amount of an alkaline compound of po
Temperature __________________ __ About 625° C.
tassium and from 2 to 25 mol percent of bismuth
Butylene gaseous hourly space ve
Steam gaseous hourly space velocity- About 7000
oxide.
4. A process for the continuous production of
butadiene from normal butylene by dehydrogen
Pressure (at exit) __ About 1 atmosphere absolute
ation which comprises continuously contacting
The operation was carried out continuously.
The catalyst did not show any noticeable induc
anormal butylene in the presence of at least two
mole of steam per mol of butylene at a tempera
ture above about 580° C. and at a gaseous hourly
space velocity between about 300 and 3000 with a
locity __________________________ __ About 500
tion period. The conversion of butylene to buta
diene remained substantially constant at about
22%. The conversion e?iciency was about I75%.
In the above I have described. and illustrated a
is
dehydrogenation catalyst consisting essentially of
an alkalized essentially homogeneous mixture of
2,408,139
.
10 r
iron oxide and bismuth oxide, containing said iron
of steamper mol of mono-ole?n at a temperature
oxide as the major constituent and from 1 to 40
mol percent of bismuth oxide.
5. A process for the continuous production of
a diole?n from the corresponding mono-ole?n by
catalytic dehydrogenation which comprises con
tinuously contacting a mono-ole?n having at
least four non-quaternary carbon atoms in a
straight chain in the presence of at least two
above about 580° C. and at a gaseous hourly space
velocity between about 300 and 3000 with a de
hydrogenation catalyst consisting essentially of
an essentially homogeneous mixture of iron oxide,
bismuth oxide and potassium oxide, containing
said iron oxide as the major constituent, a minor
amount of potassium oxide and from 2 to 25 mol
percent of bismuth oxide.
'
7. A process for the continuous production of
mols of steam per mol of ‘mono-ole?n at a tem 10
perature above about 580° C. and at a gaseous
a diole?n from the corresponding mono-ole?n by
catalytic dehydrogenation which comprises con
tinuously contacting a mono-ole?n having at‘
least four non-quaternary carbon atoms in a
sentially of an essentially homogeneous mixture
of iron oxide, bismuth oxide and potassium oxide, 15 straight chain in the presence of at least two mols
of steam per mol of mono-ole?n at a temperature
containing said iron oxide as the major constitu
above about 580° C. and at a gaseous hourly space
ent and from 1 to 40 molnpercvent of bismuth
hourly space velocity between about 300 and 3000'
with a dehydrogenation catalyst consisting es
velocity between about 300 and 3000 with a de
oxide and from 0.2 to 5 mol percent of potassium
hydrogenation catalyst consisting essentially of
oxide.
6. A process for the continuous production of 20 an alkaliz-ed essentially homogeneous mixture of
iron oxide and bismuth oxide containing said
a diole?n from the corresponding mono-ole?n by
catalytic dehydrogenation which comprises con
iron oxide as the major constituent and from 1
to 40 mol percent of bismuth oxide.
‘
tinuously contacting a mono-ole?n having at
least four non-quaternary carbon atoms in a
CARLOS L. GUTZEIT.
straight chain in the presence of at least two mols 25
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