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Патент USA US2411726

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Patented Nov. 26, 1946 '1
< 2,411,726
umrao's'ra'ras ' PATENT OFFICE PRODUCTION OF ABOMATIC
HYDRO CARBON8
itonald Holroyd and David Hallam Primrose Peel,
Norton-on-Tees, England, assignora to Imperial
’
Chemical Industries Limited, a corporation‘ of
v Great Britain
,No Drawing. Application March 3, 1942, Serial
No. 433,238. In Great Britain April 20, 1939
‘ 15 Claims.
(01.260-668)
tween 250° C. and 400° C., the life of the catalyst
This invention relates to the catalytic dehydro
genation of saturated cyclic hydrocarbons having
at least one ring containingsix carbon atoms
is lengthened by carrying out the reaction in _
the presence of added hydrogen.
with any given catalyst, reaction material,
throughput and reaction temperature, as the
amount of added hydrogen is increased the rate‘
ple, methyl cyclohexane and dimethyl- cyclo
of catalyst deterioration decreases and ?nally
hexanes, to the corresponding aromatic'hydro- I
reaches» zero. With further increase in the
carbons, for example, toluene and xylenes.
amountof hydrogen added the rate of deteriora
It is known to dehydrogenate pure hexamethyl
, ene naphthenes and mixtures thereof into the 10 tion of catalyst ‘activity remains zero, but even
(hereinafter referred to as hexamethylene ‘naph
themes) or mixtures containing them for exam
’ tually a concentration of hydrogen, depending on
corresponding aromatic hydrocarbons by heating
the other conditions of operation, is reached at
them in the presence of highly ‘active catalysts,
which hydrogenation predominates over dehydro
genation. It will be understood that such
for example, rare metals. However, in carrying
out this process it is found that the highly active
catalysts rapidlyv deteriorate if the hexamethylene 15 amounts of hydrogen which cause hydrogenation
to predominate over dehydrogenation should not
naphthenes are accompanied by para?ln hydro
carbons, and/or pentamethylene naphthenes
(cyclopentane homologues), and/or unsaturated
be added. .
Generally it will be found desirable to add an
amount of hydrogen whichprevents any loss of
activity of the catalyst during a period of at
and its compounds. The term “toxigen,” as em 20
least 100 hours.
ployed in "the appended claims, is to be under
hydrocarbons, such as oleiines, and/or sulphur
'
. The amount of hydrogen required'to achieve
stood as signifying one of those substances just
enumerated which cause rapid ‘deterioration of
such highly active catalysts in the stated dehy
drogenation process. -
any given diminution in the rate of deterioration
' of catalyst activity can be readily gauged by
25 small scale trials. It depends on the reaction
material and the reaction conditions, and in
We have now found that, in the ‘dehydro
.creases with the temperature, with the concen- .
genation to the corresponding aromatic hydro
car-bons of hexamethylene naphthenes in mix; I
trationv ofpara?ins, pentamethylene naphthenes,
unsaturated hydrocarbons, sulphur and its com
30 pounds in the reaction material, and with the
_ bons and/or pentamethylene naphthenes and/or
working pressure.
‘
_
unsaturated hydrocarbons and/or small amounts
It is desirable that sulphur and its compounds
of sulphur or sulphur compounds by_‘treatment
should be as low in concentration as possible in
of the mixtures at temperatures not exceeding
‘the reaction vessel since, these have been found
450° C. in the presence of highly active dehydro
genating catalysts, the rate of deterioration in 35 ,to have a very unfavourable effect on the reac
tion. Unsaturated hydrocarbons should also be
activity of the said catalysts can be diminished
present in as low a concentration as possible. In
and even reduced to zero by adding hydro-gen at
addition, carbon monoxide, and any substances
the commencement of the reaction zone. The
capable of giving rise to the same under the re
hydrogen to be added may be obtained from
external sources or may be that previously pro 40 action ‘condltions, for example carbon dioxide, oxygen or steam, as well as ammonia, and other
duced in the dehydrogenation itself, after sep
nitrogen compounds, should be kept low in con
aration‘ from the other reaction products, for
centration or removed entirely from the hydrogen
example byv cooling.
According to the invention, therefore, in a 45 fed to the reaction since‘these also have been
found to have an unfavourable effect on the re
process for the dehydrogenation to aromatic hy~
action. If desired, the reaction material to be
drocarbons of the corresponding hexamethylene
dehydrogenated and/or the hydrogen to be added
naphthenes in a mixture containing also para?in
‘may
be subjected to a preliminary treatment to
hydrocarbons and/or pentamethylene hydrocar
remove
constituents harmful to the catalyst, or
bons and/or unsaturated hydrocarbons and/or 50
to reduce their concentration.
sulphur or sulphur compounds, in the presence of
' The preliminary treatment of the reaction ma~ I
a catalyst consisting of or comprising at least one
terial
to remove sulphur may consist in subjecting
of the metals of group VIII'of the periodic sys
the crude mixture in the vaporphas'e to treatment
tem excepting iron, cobalt and nickel, supported ~ with
hydrogen in the presence of a mild hydro
on activated carbon, maintained at a temper
tures of the same containing parail‘ln hydrocar
‘ ature not exceeding 450° C. and preferably be
a
55
genating catalyst whereby sulphur compounds
9,41 1,790
4
are converted into hydrogen sulphide which is
then removed from the hydrocarbons in any con
one or more stages, with or without recycling a
proportion of the products.
venient manner. Such a preliminary hydrogena
tion treatment also serves to decrease the amount
of unsaturated hydrocarbons in the mixture 5
which have been found to have a detrimental
effect on the life. of the catalyst. It is pre
ferred to employ for this preliminary treatment
a hydrogenating catalyst which is also capable of
absorbing the hydrogen sulphide so that the va
pours from the preliminary hydrogenation stage
can be passed to the dehydrogenation stage
without condensation which would otherwise be
necessary in order to separate the hydrogen sul
15
phide from the hydrocarbons.
The highly active dehydrogenating catalysts
employed according to the invention may be pre
pared in any known manner, for example in the
case of platinum supported on activated carbon,
Example 1
~ A petrol from the hydrogenation of a middle
oil contained by weight 5.9% aromatics, 42.5%
para?in hydrocarbons, 35.5% pentamethylene
naphthenes, and 16.1% of hexamethyiene naph
thenes, This petrol was distilled to give 44% by
weight of a fraction boiling up to 95° C. and 56%
of a heavier fraction boiling above 95° C. The
separation into two fractions concentrated 90%
of the hexamethylene naphthenes present in the
total petrol into the heavier fraction, while this
fraction only contained 25% of the para?ln hy
'drocarbons present in the total petrol. The
heavier fraction boiling above‘ 95° C. contained
8%‘ aromatic hydrocarbons, 19% para?ln hydro
carbons, 747% pentamethylene naphthenes and
the latter may be impregnated with a solution of 20 26% of hexamethylene naphthenes.
The heavier fraction was then subjected to a
chloroplatinic acid, dried and reduced in a stream
of hydrogen, preferably in the reaction vessel it
self.
The dehydrogenation is preferably carried out
preliminary treatment for the removal of sul
phur compounds‘ by passage with hydrogen, in
the vapour phase and at atmospheric pressure,
at atmospheric pressure, but pressures higher 25 over a mildly h'ydrogenating catalyst consisting
of a mixture of zinc oxide and nickel made by
than atmospheric may be used if desired. The
reduction in hydrogen at 400° C. of a mixture of
hydrogen pressure, however, must obviously not
1 part of zinc carbonate to 24 parts of nickel car
be so great as to cause hydrogenation to pre
bonate. The treatment was carried out at a tem
dominate over dehydrogenation.
perature of about 290° C. with a feed. rate of 0.5
The present invention is particularly valuable 30 kilogram/litre of catalyst/hour and a hydrogen
for improving the anti-knock quality of petrols
concentration of 150 cubic metres of pure hydro
containing hexamethylene naphthenes. It is pos
gen/ton of material treated. The hydrogen sul
sible to treat the whole of a petrol by the process
phide produced by the reaction was absorbed by
of the present invention with this end in view, 35 the catalyst, which had to be removed from time
but it is preferable to separate it ?rst into two
or more fractions, one or more of which is richer
> to time.
The dehydrogenation treatment was carried
in hexamethylene naphthenes than the original
out over a catalyst’ consisting of 5% of platinum
petrol, and then to treat the fraction or frac
,supported on steam-activated cocoanut-shell
tions richer in hexamethylene'naphthenes by the 40 charcoal. It was made by impregnation of the
method of the present invention. The products
charcoal with a solution of chloroplatinic acid,
of dehydrogenation may then be added wholly
with subsequent reduction, after drying, at 350°
or in part to the whole or part of the untreated '
C. in a stream of pure hydrogen in the reaction
fraction or fractions.
The petrol may be sepa
vessel itself.
_
rated into two fractions, the out being made at 45
The vapours of the heavier petrol fraction.
a temperature between 80° C. and 120° C., for
after pretreatment as described above, were then
example 95° C. The higher boiling fraction
passed over the above dehydrogenation catalyst
thereby contains a larger proportion of hexa- .
at atmospheric pressure and at a rate of 2.5 kilo
methylene naphthenes and at the same time a
grams/litre of catalyst/hour, together with 640
relatively smaller proportion of para?in hydro 60 cubic metres of pure hydrogen/ton of reaction
carbons than the original petrol. By subjecting
material. At a temperature ranging from 280° C.
only the higher boiling fraction to dehydrogena
to 320° C. through the catalyst, the whole of the
tion the advantages as compared with treating
26% of hexamethylene naphthenes present in
the whole petrol are that the quantity of reac-,
this petrol fraction were dehydrogenated to the
tion material. treated in the dehydrogenation 55 corresponding aromatic hydrocarbons. The va
plant is smaller, more satisfactory operation of
pours were then condensed, giving a dehydro
the catalyst is obtained because of the smaller
genated product which contained 34% aromatic
amount of para?in hydrocarbons and that there
hydrocarbons, 19% para?in hydrocarbons and
is less’loss of low boiling constituents by entrain
47% of pentamethylene hydrocarbons.
ment in the gas stream.
The dehydrogenated product was then mixed
60
Separation of the petrol into more than two
with the untreated fraction boiling below 95° 0.,
fractions is of advantage where it is desired to
thereby giving a petrol which then contained 22%
dehydrogenate the various hexamethylene naph
of aromatic hydrocarbons as against the original
thenes under different conditions, or to adjust
5.9%, while the octane number was then 80 as
the characteristics of the ?nal petrol, or to ob 65 against an original 75.
_
tain particular fractions of aromatic hydro‘
Dehydrogenation of the hexamethylene naph
carbons.
'
thenes to the corresponding aromatic hydrocar
It is possible by the present invention to dehy
bons is substantially the only reaction. Forma
drogenate substantially the whole 0! the hexa
tion of unsaturated hydrocarbons by dehydro
methylene naphthenes in the reaction material, 70 genation of the paraf?ns or pentamethylene
but obviously, where required, it is possible, by
naphthenes was less than 1/z% of the reaction
suitable selection of operating conditions to de¢
material, while less than 1% of the reaction ma
,hydrogenate any desired proportion of the hexa
terial was broken down to hydrocarbon gases.
methylene naphthenes in the reaction material.
With the above amount of pure hydrogen
The dehydrogenation may be carried out in
added to the reaction material very satisfactory
o
9,411,700
of hydrogen added, the higher this proportion the
operation was obtained and the catalyst did not
lower is the poisoning effect or a given amount
.deteriorate over a period of 500 hours, dehydro
genation oi’ the whole of the hexamethylene.
naphthenes present in the reaction material be
ing attained without any further adjustment oi’
the reaction conditions.
'
or sulphur.
We claim:
,.
7
a
l. A process for the dehydrogenation to aro
matic hydrocarbons or the corresponding hexa-v
methylene naphthenes contained in a mixture
-
containing also at least one toxigen, which com
prises separating from the mixture a relatively
Example 2
Another petrol fraction containing 45% or
heavy fraction richer in hexamethylene naph
hexamethylene naphthenes, . which on testing 10 thenes than said mixture and, having an initial
with mercury gave an indication of the presence
boiling point between 80° C. and 120° C. and sub
of sulphur, after a mild hydrogenation treatment
jecting said fraction together with added hydro
as described in Example 1 was passed over the
gen at a temperature not'exceeding450“ C, to
I , dehydrogenation catalyst of Example 1 under the
conditions described therein, but with 380 cubic
.metres of pure hydrogen added per ton reaction
material. A 100% conversion of the hexameth
ylene' naphthenes was obtained over a period of
100 hours.v Dehydrogenation treatment of the
15
the action of a catalyst containing at least one
of the metals of group VIII of the periodic sys
tem except iron, cobalt and nickel, supported on
activated carbon, the proportion oi.’ hydrogen add
ed being' suilicient to prevent substantial loss'oi'
activity of the catalyst during a prolonged‘ op
original petrol fraction without the preliminary - 2,0 erating period, but not suf?cient to cause hydro
hydrogenation treatment to remove sulphur com
. pounds gave only 80% conversion of the hexa
methylene naphthenes present.
-
genation to predominate over dehydrogenation.
2. A process for the dehydrogenation to aro
a
The following data illustrate the e?ects of vari
ations in the amount of added hydrogen and in '
the amount of sulphur compounds present.
(1) Effect of varying the amount of added
hydrogen
.
With the same reaction material described in
Example 1, and the same catalyst and reaction
conditions, no deterioration of the catalyst was
matic hydrocarbons of the corresponding hexa
methylene naphthenes contained in a mixture
containing also a deleterious sulphur compound
which comprises largely removing s'aid compound
_- from the mixture and subjecting the residual
mixture together with added hydrogen at a tem
perature. not exceeding 450° C. to the action of
a catalyst containing at leastione of the metals.
of group VIII of the periodic system except iron,
cobalt and nickel, supported on activated carbon,
apparent over a period of 100 hours when 380 I the proportion of hydrogen added being suiiicient
cubic metres of pure hydrogen were added per
to prevent substantial lossof activity or the cat
ton of reaction material instead of 640 cubic
alyst during a prolonged operating period, but
metres per ton. However, with 160 cubic metres
"not su?icient to cause hydrogenation to pre
per ton, the conversion of hexamethylene naph
dominate over dehydrogenation.
thenes to aromatic hydrocarbons fell from 100%
- 3. Av process for the dehydrogenation to aro
to 97% in 15 hours. With only 64 cubic metres
matic hydrocarbons of the-corresponding hexa
per ton the conversion fell to 79% in 2'7 hours, 41 methylene naphthenes contained in a mixture
while with 32 cubic metres per ton the conversion
fell to 64% in 18 hours. With no added-hydro
gen the conversion fell very rapidly to 48% in
12 hours. In all cases where the catalyst is de
teriorating due to insu?icient hydrogen there is
some formation of unsaturated hydrocarbons
which contribute to the deterioration oi’ the cat
alyst.
. containing also a deleterious sulphur compound
which comprises subjecting the said mixture in
the vapour phase to treatment with hydrogen in
the presence of‘ a mildhydrogenating catalyst so
'as largely to convert the sulphur of said com
pound into hydrogen sulphide, separating the
hydrogen sulphide from the mixture and sub
' jecting the residualmixture together with added
'
(2) Effect of d'i?erent amounts of sulphur
compounds
A petrol fraction boiling above 95° C. and con
taining 30% of hexamethylene naphthenes, after
it ‘had been subjected to the preliminary mild
' hydrogenation process for sulphur removal de
scribed in the above example, was subjected to
dehydrogenation. Complete conversion of the
hexamethylene naphthenes to aromatic hydro
, carbons was maintained under the reaction con
50 hydrogen at a concentration of between 200 and I
640 cubic meters per ton of mixture treated, and
at a temperature not exceeding 450° C., to the
action of a catalyst containing at least one of- the
metals of. group VIII oi’ the periodic system ex
' c'ept iron, cobalt and nickel, supported on acti
vated’ carbon.
‘ 4. A'process for the dehydrogenation to aro-~
matic hydrocarbons of the corresponding hexa
methylene naphthenes contained in a mixture
containing also at least one toxigen which com
ditions described in Example 1 for a period of 60 prises separating from the mixture a relatively
200 hours, with the addition of 640 cubic metres
of pure hydrogen/ton of reaction material, Ad
dition of 0.0035% by weight of sulphur to the re
action material, either as propyl sulphide or as
thiopene, reduced the conversion from 100% to
11% in a period of 30 hours.
In another case,
the addition of 0.000'7% by weight of sulphur as
propyl sulphide reduced . the conversion from
100% to ‘74% in 40 hours, while addition of
heavy fraction richer in hexamethylene naph
thenes than said mixture and having. an initial
boiling point between 80° C. and 120° C. and sub
jectin'g said fraction together with- added hydro-J
gen at a temperature between 250° C. and 400° C.
to the action of a catalyst containing at least
one of the metals of group VIII of the periodic
> system except iron, cobalt and nickel, supported
on activated carbon, the proportion of hydrogen
0.008'l% of sulphur reduced the conversion to 70 added being suf?cient to prevent substantial loss
5% in the same period. In each case 640 cubic
of activity of the catalyst during a prolonged
metres of pure hydrogen per ton were added and
operating period, but not su?lcient to cause hy-p,
in each case the activity of the catalyst reached
-drogenation to predominate over dehydrogena
a constant level and did not fall'further. This
_ level of activity is dependent on the proportion 75 tion.
9,41 1,786
7
.
5. A process for the dehydrogenation to aro
matic hydrocarbons of the corresponding hexa
methylene naphthenes contained in a mixture con
taining also at least one toxigen, which comprises
separating from the mixture a relatively heavy
fraction richer in hexamethylene naphthenes
containlng also at least one toxigen, which com
prises subjecting the mixture in vapor phase,
together with added hydrogen, at a temperature
not exceeding 450° C., to the action of a catalyst
containing at least one of the metals of group
VIII or the periodic system except iron, cobalt
than said mixture and having an initial boiling
and
nickel, supported on activated carbon, the
point between 80° C. and 120° C. and subjecting
proportion of hydrogen added being suil'lcient to
said fraction together with added hydrogen in‘an
prevent substantial loss Of activity 01' the cat
amount of at least 200 cubic metres per metric 10 alyst during a prolonged operating period, but
ton of the fraction and at a temperature not ex
not sufficient to cause hydrogenation to predom
ceeding 450° C. to the action of a catalyst con
inate over dehydrogenation,
taining at‘least one of the metals of group VIII
9. A process for the dehydrogenation to aro
of the periodic system except iron, cobalt and
matic hydrocarbons of the corresponding hexa
nickel, supported on activated carbon, the pro 15 methylene naphthenes contained in a mixture
portion of hydrogen added being su?icient to pre
containing also at least one toxigen, which com
vent substantial loss of activity oflthe catalyst
prises subjecting the mixture in vapor phase, to
during a prolonged operating period, but not suf
gether with added hydrogen, at a, temperature
?cient to cause hydrogenation to predominate
not exceeding 450° C., to the action of a catalyst
over dehydrogenation.
20 containing at least one of the metals of group
6. A process for the dehydrogenation to aro
VIII of the‘periodic system except iron, cobalt
matic hydrocarbons of the corresponding hexa~
and nickel, supported on activated carbon, the ‘
methylene naphthenes contained in a‘ mixture
proportion of hydrogen added being su?icient to
containing also at least one toxigen, which com
prevent substantial loss of activity ‘of the catalyst
prises separatingfrom the mixture a relatively
during an operating period of at least one hun
heavy fraction richer in hexamethylene naph 25 dred hours, but not su?icient 'to cause hydro
thenes than said mixture and having an initial
genation to predominate over dehydrogenation.
boiling point between 80° C. and 120° C. and sub
10. The process de?ned in claim 8 wherein the
jecting said fraction together with-added hydro
hydrogen is added in the proportion at; at least
gen at a temperature not exceeding 450° C. to
200 cubic meters per ton of reaction ma erial.
the action of a catalyst containing platinum sup 30
11. The process de?ned in claim 8 wherein the
ported on activated carbon, the proportion or
operating temperature is maintained between
hydrogen added being su?icient' to prevent sub
250° C. and 400° C.
'
stantial loss of activity of the catalyst during a
12.
The
process
de?ned
claim 9 wherein the‘
prolonged. operating period, but not su?icient to 35 operating temperature is in~m'aintained
between
cause hydrogenation to predominate over de
‘ hydrogenation.
250° C. and 400° C. '
'
13. A process for the dehydrogenation to aro
7. A process for the dehydrogenation to aro
matic hydrocarbons of the corresponding hexa
matic hydrocarbons of the corresponding hexa
methylene naphthenes contained in a, mixture
methylene naphthenes contained in a mixture 40 containing also at least one toxigen, which com
containing also a deleterious sulphur compound
prises subjecting the mixture in vapor phase, to
which comprises subjectingv the said mixture in
gether with added hydrogen, at a temperature
the vapour phase to treatment with hydrogen
not exceeding 450° 0., to the action of a catalyst
in the presence of a mild hydrogenating catalyst
containing platinum supported on activated car
so as largely to convert the sulphur of said com
bon, theproportion of hydrogen added being su?i
pound into hydrogen sulphide, separating the hy
cient to prevent substantial loss of‘ activity of
drogen sulphide from the mixture and subjecting
the catalyst during an operating period of at
the residual mixture together with added hydro
least one hundred .hours, but not su?lcient to
gen at a temperature not exceeding 450° C. to
cause hydrogenation to predominate over de
the action of a catalyst containing platinum sup 50 hydrogenation.
porting on activated carbon, the proportion of
14. The process de?ned in claim 13, wherein
hydrogen added being sufficient to prevent sub
the hydrogen is added in the proportion of at
stantial loss of activity of the catalyst during a
least 200 cubic meters per ton of reaction ma
prolonged operating period, but not su?icient to
terial.
cause hydrogenation to predominate over dehy 55
15. The process de?ned in claim 13, wherein
drogenation.
the operating, temperature is maintained be
8. A process for the dehydrogenation to aro
tween 250° C. and 400° C.
matic hydrocarbons of the corresponding hexa
RONALD HOLROYD.
methylene naphthenes contained in a mixture
DAVID HALLAM PBIMROSE PEEL.
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