Патент USA US2389215

NOV- 29, 1945.
H. M. SINGL’ETON
. 2,389,215
PROCESS FOR DEHYDROGENATING HYDROCARBONS
Filed Feb. 15, 1943'
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WM’. INVENTOR.
BY
Mm
ATTORNEY
Patented Nov.,20, 1945
_ * 2,389,215
UNITEDVSTATES PATENT OFFICE. I -j
,
2,389,215
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PROCESS FOR DEHYDBOGENATING A
HYDROCABBON
Henry M. Singleton, Goose Creek, Tex., assignor
to Standard Oil Development Company,-a cor
poration of Delaware
Application February 15, 1943, Serial No. ‘475,866
12 Claims.
(Cl. 260-669)
The present invention is directed- to the de
hydrogenation of hydrocarbons.
,
In recent years dehydrogenation has become
an extremely important tool to the re?ner of
petroleum oil. It is one treatment to which gaso-v
line is subjected in order to improve its octane
number. Most of the important syntheses start
with unsaturated hydrocarbons which do not
occur naturally and must be otbained primarily
by dehydrogenation of naturally occurring sat
urated hydrocarbons.’
which are contemplated for use in accordance
with the present invention. These various com
pounds will be referred to hereinafter as hydrogen
acceptors.
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These organic compounds are characterized, in
addition to their property of combining readily
with hydrogen, by their susceptibility to decom
position into free radicals at elevated tempera
tures. The formation of these free radicals en
10 hances the power of these organic compounds
Ole?ns'for use in poly- ‘
to consume hydrogen, particularly the nascent
merization and ‘alkylation are obtained by de
type, which results from the dehydrogenation of
hydrocarbons. Under certain conditions these
hydrogenation of the corresponding paramns.
Diole?ns ‘for the production of rubber are ob
free radicals combine either with themselves or
tained by further dehydrogenation of the ole?ns. 15 with the dehydrogenatedhydrocarbons to yield
Diole?ns, such as butadiene, are also obtained
useful by-products. The generation of these free‘
from hydroaromatic hydrocarbons by a reaction
radicals can be controlled by the use of suitable
which involves dehydrogenation. For example, ,
addition agents. For example, small percentages
cyclohexane is ?rst dehydrogenated to cyclo
of acid-reacting substances, such as strong min-‘
hexene, which then breaks down into butadiene 20 eral acids, tend to acceleratethe production of
and ethylene. Polymerizable aromatic hydrocar
free radicals from these compounds, while the
bons, such'as styrene, are obtained from alkylated
compounds‘are stabilized and the formation of
aromatics by‘aiehydrogenation.
_free radicals suppressed by the presence of basic
From the foregoing discussion it will be evi
substances such as ammonia or amino compounds.
dent that the process of dehydrogenation of hy 25 Thus, if, in a given reaction, the operating tem
drocarbons is one which has been intensively
perature is such as to promote the decomposition
studied with a, view of increasing its economy and
of the hydrogen acceptor and such decomposi
efficiency. Various catalysts have been suggested
tion is not desired, a certain percentage of am
as promoters of dehydrogenation. The condi
monia, aniline, pyridine, or the like is included
tions best suited for dehydrogenation of various 30 in the feed stock. On theother hand, if, under- _
hydrocarbons in the presence of and in the ab
the operating conditions, the hydrogen acceptor
sence of catalysts have been fairly well estab
is relatively stable and decomposition thereof is
lished after careful investigation. The e?ect of
desired, either for the purpose of increasing the
pressure, including the partial pressure of hy
hydrogen consumption or of producing additional
drogen, on the reaction has been fully disclosed 35 amounts of desired end product, a small amount
in the literature.
of an acidic substance, such as nitric acid, h-y- I
According to the present invention, the ef
drochloric acid, sulfuric acid, sulfur dioxide, or
?ciency and economy of processes involving the
the like is included in the feed.
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dehydrogenation of hydrocarbons are favorably
The various dehydrogenation reactions con
in?uenced by carrying out the dehydrogenation 40 templated by the present invention are well es
in the presence of certain organic compounds
tablished in the art, and the operating conditions
which possess the property of rapidly consuming
therefor are well known. The modi?cation of
large quantities of hydrogen, and in some cases
these well known processes by the‘ present inven
cf undergoing conversion themselves to yield fur
tion does not necessarily alter these operating
53-1181‘ quantities of the desired reaction product. 45 conditions, although the invention does afford
"l'hese organic compounds may be referred to
the possibility of increasing the desired conver
generally as heterocyclic compounds,-which.in-'
sion at any given set. of conditions.v To put it,
clude in their ring structure at least one of’ the _
elements oxygen, nitrogen, and sulfur. Examples
of such organic compounds are furan, thiophene,
pyrrole and derivatives thereof. Readily avail
able compounds ofthis type are furfural and
another way, the present invention makes -pos-,
sible the realization under milder conditions of ~
50 yields heretofore requiring more severe condi
. tions. As has previously been indicated, the pres
ent invention is applicable to dehydrogenation
effected both by heat alone, as well as by heat
and catalysts. Suitable catalysts for these reac
‘ types speci?ed above are typical of compounds 55 tions are numerous and fully disclosed .in the
furf‘uryl alcohol. The alkyl derivatives and the
partial reduction compounds of the three general
i
2,889,216
2
reactions may occur. After the process is once
prior art. Especially effective catalysts are oxides
started, all of the fresh feed may be introduced
by way of line 6. The mixture of reaction prod
uct and fresh feed is conducted by line ‘I to a
fractionating tower 8, ahead of which is ar
ranged atemperature controlled unit 9 which may
be utilized to impart heat to, or cool, the mix—
ture in line ‘I, as required. The fractionator 8
and sulfides of metals of group VI of the periodic
system, alone or in conjunction with supports
such as activated aluminum. Molybdenum sul
?de and chromium oxide may be mentioned as
representative examples of group VI dehydro
genation catalysts.
In general, dehydrogenation reactions contem
is so operated as to give off, as an overhead
plated by the present invention are carried out
stream through line I0, butadiene and lower boil
10
at temperatures ranging from about 600° to
ing compounds. Unreacted cyclohexane is with
1400“ F. Reactions which involve the conversion
drawn. as bottoms by way of line I I and recycled
of ole?ns to diole?ns are ordinarily carried out
to line I.
in the upper end of this range, while the dehydro
genation of the para?ins to ole?ns is ordinarily
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The temperature inside reactor 3 is maintained .
preferably between about 1l00° and 1400" F.
The pressure should preferably be less than about
100 lbs/sq. in., 30 lbs/sq. in. being satisfactory.
At this pressure the partial pressure of the re
acting material is reduced by including in the
conducted in the lower end of the range. A
higher operating pressure than ordinarily em
ployed in dehydrogenation is permissible in the
practice of the present invention because the re
action, when carried out according to the present
invention, is not necessarily accompanied by an
increase ‘in volume. Pressures as high as 250
lbs/sq. in. may be employed, but lower pressures I
are preferred. It is advantageous to dilute the '
reaction mixture with an inert gas, such as nitro
gen, steam, molecular hydrogen, or natural gas.
A ratio of diluent-to product as high as 50:1 may
be employed, but preferably this ratio is main
reaction mixture an inert gas. For this purpose,
steam may be introduced into line I by way of
branch line I2. Nitrogen may be used if desired.
Methane is also a useful diluent and in some cases
may find its way into the ?nal product, as herein
after suggested.
In operating according to the present inven
tion, a hydrogen acceptor is introduced into line
I by branch line I3. In the particular embodi
ment shown, the hydrogen‘ acceptor may be as
presence of the diluent makes possible the em
sumed to be’ furfural. This hydrogen acceptor
ployment of higher pressures without giving rise 30 may be used in an amount equal to, and prefer
to excessive polymerization, to which there may
ably somewhat in excess of, the amount theo
be a considerable tendency under the operating
retically required to consume the hydrogen lib
conditions with certain hydrocarbons. The same
' erated in the conversion of cyclohexane to buta
tained below 20:1 when diluent is used.
The >
effect as that realized with a diluent may be ob
diene and ethylene. Of course, for a lesser effect
tained by using a su?iciently high feed rate to 35 a smaller amount of the hydrogen acceptor is em
provide a large amount of unreacted feed at all
ployed. There is no objection to using a con
times in the reaction chamber. ‘This type of oper- - siderable‘excess of the hydrogen acceptor, except
and
ation yields only a low conversion per pass,
that it reduces the capacity of the unit for the
involves considerable recycling.
desired reaction. A slight excess over stoichio- .
The nature of the present invention may be 40 metrical requirements will ordinarily be satis
better understood by reference to the accompany
factory. Under the particular conditions em
ing drawing, in which is shown, in front eleva
ployed furfural, in taking up hydrogen, is con
tion in diagrammatic form, an apparatus of the
verted ?rst to furfuryl alcohol, which, through
type suitable for the practice of the method.
further absorption of hydrogen, yields piperylene
In referring to the drawing in detail, a spe
as an end product. Piperylene is a highly desir
cific embodiment of the process of the present
able by-product since it may be used as a raw
invention will be discussed. This particular em
material for the production of synthetic rubber,
bodiment is the production of butadiene from
either by way of polymerization or copolymeriza
cyclohexane, to the treatment of which the appa
tion with isobutylene or butadiene or other rub
ratus shown is particularly adapted. Itwill be
understood, of course, that, with slight modifica
tion, the apparatus can be used forthe dehydro
genation or conversion of other materials.-
ber forming unsaturated hydrocarbons. Pipery_
lene is advantageously recovered from the system
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Numeral one designates a. fresh feed line, in
which is arranged a heating coil 2, where the feed
stock is supplied with suflicient heat to support
the subsequent reaction. The feed is discharged
as a side stream from fractionator 8 by way of
draw-oi! line I4. Any unconverted furfural or
residual furfuryl alcohol or intermediate prod
ucts boiling above piperylene and still capable of
taking up hydrogen go into the bottoms with un
clzlonvfrted cyclohexane and are returned to inlet
from line 1 into the bottom of reactor 3, which,
in the particular case illustrated, is provided at
It is believed to be evident that, instead of
its lower end with a bed 4 of catalytic material 60 using
furfural as the initial hydrogen acceptor,
effective for catalyzing dehydrogenation. Also
furfuryl
alcohol may be employed with equal suc
included in the catalyst bed may be substances
cess. It may beobserved that, depending upon
‘which favor the splitting of molecules, such as
the specific conditions of working employed, the
free iron, nickel, cobalt, copper, and the like. In
hydrogen acceptor may exhibit a greater or lesser
the upper part of reactor 3 is provided a heating
tendency to decompose into free radicals. As has
element 5 which may be used to supply any heat
'ne
required to complete the conversion of the cyclo
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previously been suggested, this tendency may be
enhanced by adding a small amount of an acid
hexane to butadiene and ethylene.
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reacting substance to the feed. When an acid
Arranged as close to ‘the outlet of reactor 3 as
convenient is an inlet line 6 for the introduction 70 reacting substance is employed it may be used in
an amount ranging from 0.01% to about 10% of
of cold fresh feed. The purpose of introducing
cold feed at this point is to quench the reaction ' the hydrogen acceptor. Ordinarily, the concen
tration of the acid-reacting substance need not
products so as to reduce them, as rapidly as possi
substantially .exceed 1% of the hydrogen ac
ble, from reaction temperature to a temperature
below that at which polymerization and other side ' 75 ceptor. Particularly when methane is employed
2,889,915
as a diluent, it is desirable to promote the fema
tion of free radicals in the reactor. In this cue,
a substantial excess of the hydrogen acceptor
over that normally required to assimilate the hy
drogen given up by the cyclohexane is‘advan
tageous. With methane and free} radicals pres
ent in the reactor, the yield of useful product is
increased by including phosphoric acid either in
the catalyst bed 4 or by arranging a separate bed
3.
molecular weight of the initial hydrocarbon ma
terial.
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3. A process for converting a hydrocarbon into
a less saturated hydrocarbon which comprises
subjecting the hydrocarbon in admixture with
an organic heterocyclic compound containing a
plurality of double bonds in its ring structure to t
a temperature sufiicient to split 0!! hydrogen
from said hydrocarbon and favoring formation
of phosphoric acid on a suitable support, such as 10 of‘ free radicals from said organic heterocyclic
silica gel or activated alumina in the upper part
compound, the formation of free radicals being
of the reactor. In this case, a more careful
promoted by adding to the organic heterocyclic
fractionation of the product, or additional frac
tionation of the bottoms drawn oil.’ from frac
tionator 8 by line I I is advisable.
In like manner, if the operating conditions are
such that an undesirably high‘ conversion of the
compound an acid reacting substance.
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,4- A process in accordance with claim 3 in
which the acid reacting substance is a mineral
acid.
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5. A process for dehydrogenating a hydrocar
hydrogen acceptor into free radicals occurs in
bon which comprises subjecting the hydrocarbon
the reactor 3, there is added to the reaction mix
in admixture with a compound of the furan se
ture, by way of line II, a basic substance in addi 20 ries to a temperature between 600° F. and 1400'
tion to the hydrogen acceptor. ' A suitable basic‘
substance for this purpose is aniline or pyridine,
although ammonia itself may be employed.
F., said dehydrogenation being promoted by ad
dition of a mineral acid to said compound of
the furan series. _
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When the apparatus shown in the drawing is '
6. A process in accordance with claim 5 in
utilized for the dehydrogenation of other hydro 25 which the mineral acid added to said compound
carbons, such as the dehydrogenation of para?ins
to the corresponding ole?ns, it may be advan
tageously modi?ed by either ?lling the reactor 3
entirely with catalyst or, if desired, leaving the
of the furan series is in an amount ranging be
tween 0.01% to 10% of the‘ compound of the
furan series in admixture withthe hydrocarbon.
7. A process for converting; hydrocarbon into
reactor entirely empty. Likewise, in this case the 30 a hydrocarbon of less saturated nature which
comprises subjecting the hydrocarbon in admix
tion and may be omitted, the entire fresh feed
ture with an organic heterocyclic compound con- '
being introduced by way of line I. When, ‘how
taining a plurality of double bonds in its ring
ever, the apparatus is used for the conversion of
structure to a temperature sufiicient to split oi!
quenching operation serves no particular func
ole?ns into diole?ns, the quenching step is highly 35 hydrogen from said hydrocarbon and favoring '
desirable. It will be understood that the use of
the formation of free radicals, said formation of
a catalyst is not necessary in any of these dehy
free radicals being inhibited by adding to said
drogenation reactions. When the apparatus is
organic heterocyclic compound a basic substance.
used for the production of styrene from ethyl
8. A process in accordance with claim '7 in
benzene it will be understood that the fractiona
which the basic substance is a nitrogen com
tion step must be suitably modified. Here the
degradation products of‘ the hydrogen acceptor
_ 9. A process for dehydrogenating a hydrocar
boiling below styrene'are taken oi! as an over
bon which comprises adding to the hydrocarbon
head stream and the styrene taken of! as a side _
an organic heterocyclic compound containing a
stream, leaving unconverted ethylbenrene in the
plurality
of double bonds in its ring structure
bottoms together with the hydrogen acceptor
and subjecting the mixture to the action of a
where the latter is furfural or furfuryl alcohol.
dehydrogenation catalyst at a temperature be
The nature and objects of the present inven
tween about 600" F. and 1400" 1".
tion having been thus described and illustrated,
10. A method according to claim 9 in which
what is claimed as new and useful and is desired
the heterocyclic compound is used in an amount
to be secured by Letters Patent is:
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-_ranging from 0.01% to 10% of the amount of
1. A method for subjecting a hydrocarbon to a
hydrocarbon employed.
conversion involving dehydrogenation which
11. A method for converting cyclohexane into
comprises adding an organic heterocyclic com
' unsaturated compounds which comprises
pound containing a plurality of double bonds in
cyclohexane in admixture with an organic hetero
its ring structure to the hydrocarbon to be con
cyclic
compound containing a plurality of double
verted and subjecting the hydrocarbon in admix
bonds in its ring ‘structure into contact with a
ture with the organic heterocyclic compound to
dehydrogenation catalyst at a temperature be
conditions suitable for said conversion.
tween about 1100° F'. and 1400° F. fora limited
2. A method for converting a hydrocarbon into
period of time, quenching the reaction products
a less saturated hydrocarbon which comprises
pound.
adding an organic heterocyclic compound con
taining a plurality of double bonds in its ring
structure to the hydrocarbon to be converted and
subjecting the hydrocarbon in admixture with
the‘ organic heterocyclic-compound to a tem
perature su?icient to split o? hydrogen from a
said hydrocarbon, said temperature being at
least 600° F. and being higher the lower the
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and recovering unsaturated hydrocarbons there- .
from
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12. A process according to claim 11 in which
‘the reaction products are quenched with fresh
cyclohexane feed and the latter is recovered from ,
the quenched reaction products and ‘fed to the
catalyst zone.
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HENRY H; BINGIIION.
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