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Патент USA US2403757

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Patented July 9, v1946
7
2,403,757
"UNITED STATE s PATENT OFFICE
2,403,757
,
PROCESS OF ISOMERIZING DIALKYL
‘
BENZENES.
EdwardpD. Reeves, Cranford, N. J., assignor to
Standard Oil Development Company, a cor
poration of Delaware‘
N0 Drawing.
Ap'pueation August 18, 1943,
Serial No. 499,117
10 Claims.‘ (Cl. 260-668)
,
I
Q
The present invention relates to the isomeriza- .
‘ ‘The present invention resides in the prepara
tion of aromatic hydrocarbons and pertains more
tion of novel catalyst compositions which, upon
being used in the heretofore-mentioned isomer
particularly to the catalytic isomerization of
ortho substituted dialkyl benzenes."
‘
It has been known that ortho xylene and other
301'
ization reaction, obviate the dif?culties heretofore '
encountered in the known processes; Where a
corresponding ortho substituted dialkyl benzenes
liquid or vapor phase feed stock predominating
could be isomerized to meta and para forms using
in or composed solely of ortho dialkyl benzenes
aluminum chloride as the catalyst and, if desired,
is fediat a temperature between about 500° F.
hydrogen chloride as the promoter. It has also
and about 1150° F., at a throughput of between
been known in the past to isomerize and dispro 10 about 0.4 and 6.0 liquid volumes of feed per vol
portionate such ortho dialkyl benzenes under ~
temperatures of the order of 1300” F. to 1420° F.
ume of catalyst mass per hour, in contact with
a novel catalyst composition which may comprise
in the absence of any catalyst. These methods
a synthetic alumina-silica catalyst mass, su?i
are, however, disadvantageous for several reasons.
cient superatmospheric pressures are employed
In the ?rst instance, where aluminum chloride 15 within the lower’ portion of this range, that is,
is. employed, the catalyst is generally not recov
at at'emperature below 650° F. to maintain liquid
erable and considerable amounts of feed stock
phase operation if desired. Superatmospheric
were lost due to reaction with the catalyst to form
pressures may also be employed where vapor
complexes with aluminum chloride. Further
phase reaction is contemplated, generally the
more, by the complex formation over an extended 20 pressure amounting to from'1.5 to 10 atmospheres.
period of time, large losses of aluminum chloride"
occurred for ‘the same reason.‘ This, of course,
necessitates replacement of the “ ‘catalyst mass
The novel catalyst mass may be prepared in a
number of various ways. Thus, for example, a
silica gel may ?rst be formed by acidifying a
dilute solution of sodium silicate with a moderate
with aluminum chloride, or the complete shut
down of a unit while fresh, catalyst mass is sub 25 excess of an acid such as hydrochloric acid
stituted for the spent mass. In the case of the
whereby a desired silica hydrogel is obtained.
thermal isomerization of ortho xylene or other
This may then be ?ltered and washed to remove
ortho substituted dialkyl benzene, the fuel re
the sodium ions therefrom, after which the gel
quirements and the demand for special alloy steel
may be washed with ammonia to free it of acid
capable of withstanding high temperatures and 30 ions and thereafter-heated to a relatively low
pressures necessitate the expenditure of large
temperature to ‘evaporate the water. During the
sums of money, and from the economic stand
?nal stages of heating, however, the temperature
point such 'a'process is not particularly desirable,
is gradually raised to a temperature of 800° F._
where commercial scale operations are contem~
and maintained at that temperature for a period
plated.
35 of 3 hours to effect the ?nal drying of the silica
It is an object of the present invention to carry
gel. This procedure is described in the Patrick
out the isomerization and disproportionation of
Patent No. 1,297,794. To this silica gel produced
ortho dialkyl benzenes to produce the correspond
in accordance with this method or any other suit
ing meta and para isomers in the presence of
able method there is added alumina either as a
novel catalyst compositions. It is a further object 40 gelatinous precipitate of aluminum hydroxide, as
of the invention to obtain substantial amounts
alumina hydrogel, alumina hydrosol or alumina
of meta and para dialkyl benzenes by the isomer
gel, or Activated Alumina, and‘the mixture is
' ization and disproportionation of the correspond
commingled with heatingto produce the ?nal
ing ortho dialkyl benzenes through the use of
‘dried product which serves as the catalyst in the
novel’ catalyst masses which are relatively stable 45 present reaction. A homogenization treatment
‘during the isomerization and'are recoverable for
of the ‘silica and alumina may be employed if
regeneration and reuse in the process. It is a
the hydrogel of alumina and the hydrogel of silica
further object oi theinvention to conserve feed
are ?rst mixed together then homogenized and
stock and to prevent disintegration and degrada
?nally ‘dried to remove the water contained
tion of the feed stocks and catalysts employed 50 therein. A suitable catalyst composition for use 7
in the isomerization and .disproportionation of
in the present reaction contains about 87.5 weight
ortho dialkyl benzenes to form the corresponding
percent of silica gel. and about 12.5 weight per
meta vand para' forms thereof. Other objects will
cent of alumina. The mass may contain a total
be apparent upon a fuller understanding of the
‘ of 15% water but in general a smaller percentage
invention‘ herein‘ described. _
'
55 vis desirable.
2,403,757
3
4
ization and disproportionation reaction to pro
duce the corresponding meta and para dialkyl
The catalyst may also be prepared in accord
ance with the procedure outlined in U. S. appli
benzenes. Feed stocks which are suitable for use
cation No. 233,159, ?led October 4, 1938, in which
in the reaction comprise any one or more of the
a mixture of silica and alumina is formed by com
following substances: ortho Xylene; 2-ethyl tolu
bining the alumina with silica while the latter is
ene; 1,2-diethyl benzene; Z-n-propyl toluene; 2
in hydrous form and thereafter dehydrating the
isopropyl toluene, and similar Ca, Ca and C10 aro
hydrous silica.
matic ortho dialkyl benzene fractions. These
A still further method for the preparation of
may be obtained for use in the present process
catalyst compositions useful in carrying out the
process of the present invention resides in the 10 through the recovery of ortho Xylene concentrates
or C9 aromatic fractions obtained in the catalytic
impregnation of silica gel with a dry powdered
hydroforming of petroleum fractions, or the feed
alumina while the silica gel is in the form of hy
stock may also be obtained from selected frac
drogel and thereafter converting the said hydro
tions of the required boiling ranges obtained in
gel into a dry gel. A still further method of pre
paring the novel catalyst composition resides in 15 coal tar distillations. The ortho Xylene concen
trate may be easily isolated from the hydroformed
impregnating a silica gel with an aluminum com
product by efficient fractional distillation as may
pound capable of being decomposed either by heat
the C9 aromatic fraction which usually contains
or by chemical reactioninto the oxide such as, '
substantial amounts of‘ ortho dialkyl benzenes.
for example, aluminum nitrate, aluminum chlo
Also suitable feed stocks ‘are obtainable by taking
ride or aluminum acetate, followed by the suit 20
the selected cuts and fractions of aromatic type
able treatment to reduce the compound to the
from products obtained in the catalytic cracking
aluminum oxide in situ. A solution of aluminum
of petroleum re?nery fractions. The process ?nds
sulfate may be added to a silica gel either in
its greatest utility ,at the present time in using
the form of the hydrosol or as the dried gel. The
resulting mixture may then be soaked with am
25
'18 heretofore-mentioned feed stocks.
It is rec
ognized, however, that the isomerization reaction
monium hydroxide to precipitate the aluminum
involves the attainment of an equilibrium and
hydroxide. The mixture then is washed free of
that the process is also applicable to the isomeri
acid and base ions and calcined at a temperature
zation of meta and/or para dialkyl benzenes to
of around 800° F. to give the required catalyst.
produce the corresponding ortho isomers thereof.
30
Upon using aluminum nitrate, acetate or chlo
Thus, too,,a meta substituted type of feed stock
ride, the oxide is derived therefrom merely by
yields ortho and para isomers; a para type yields
heating the mass without resorting to the use of
ortho and meta isomers.
ammonium hydroxide to. convert it to the alumi
In general, the temperature lies between about
num oxide ?rst. Plural gels of alumina and sil
500°
F. and about 1150° F., although it is preferred
35
ica, wherein both are formed simultaneously in
to operate between about r750° F. and about 1025°
admixture with each other, are contemplated as
F. In general, the throughput rate is between
well.
about 0.4 and about 6.0 liquid volumes of feed
Other methods of preparing the catalyst are
stock per volume of catalyst per hour, but pref
likewise known. However, the invention is not
erably the rate of throughput lies between about
limited to any speci?c method for preparing the
0.6 and about 4 liquid volumes of- feed stock per
mixed silica-alumina catalyst mass. In general,
volume
of catalyst per hour. The process of the
the mass may contain from 2:1 to as high as
present invention is readilyadaptable to com
10:1 mols of silica per mol of alumina, although
mercial operations involving a continuous vapor
molar ratios outside of this range may likewise
phase operation in which the vaporized feed stock
be employed without appreciably affecting the ef
is passed through a bed of catalyst mass main
?ciency of the catalyst for isomerizing the ortho
tained under the required reaction conditions.
dialkyl benzenes, as more fully hereinafter de
This catalyst mass may be maintained on stream
scribed.
for between about 1 hour and about 20 hours,
In addition to the use of catalysts composed
50 preferably between about 2 and about 12 hours,
exclusively of silica and alumina as above de
after which it is removed from the reaction and
scribed, the invention also contemplates the use
the catalyst mass is subjected to a short regen
of catalysts containing, in addition to the silica
eration treatment involving 1 to 5 hours, prefer
and alumina, small amounts of metal oxides such
ably between about 2 and about 3 hours, wherein
as magnesia, thoria, zirconia and the oxide of
boron. These catalysts may be prepared by the 55 air or any other gas containing free or uncom
bined oxygen in dilute form is passed there
addition of the corresponding nitrates, acetates
through for a sufficient length of time and under
or hydroxides of these metals to the hydrogels
followed by the addition of ammonium hydroxide
to obtain a mixed mass of hydrated alumina
and/or hydrated silica coupled with hydrated
thoria, hydrated zirconia, hydrated boron oxide
or hydrated magnesia. The resultant admixture
is ?ltered and dried and after drying to a tem
perature of from 300° F. to 400° F. at ?rst, and
?nally at a temperature of 800° F. to 900° F., the
resultant catalyst mass is ready for use. The per
controlled temperature such that the carbona
ceous impurities are burned from the pores of
60 the catalyst mass within the time required, after
which the regenerated catalyst may be again
placed on stream for effecting and activating
the isomerization reaction. One of the chief ad
vantages of the present process resides in the
fact that the need for regeneration of the catalyst
mass at frequent intervals is umiecessary because
centage of the various metal oxides other than
the silica and alumina present in the catalyst
even at the relatively high operating temperatures
desired.
less of whether or not the present operation is car
ried out using'a catalyst involving a ?xed bed, a
moving bed or a ?uid catalyst type of technique.
the coke formed on the catalyst mass is of the
order of 0.6 weight per cent while ‘maintaining
mass may range between about 3% and 10% based
on the silica-alumina present, although percent 70 an ortho xylene conversion, of 60% or better.
The process is readily adaptable for combination
ages outside of these ranges may be employed if
As previously stated, the resultant catalyst mass
is employed in carrying out the isomerization of
the ortho dialkyl benzenes by-a combined isomer
with other petroleum re?ning operations regard
2,403,757 7
5
7
jThe process may be worked in conjunction with
those processes previously mentioned which pro
of meta and‘para xylenes are concerned, was-ob
vide the source ‘of orthoxylene or other ortho
dialkyl aromatics, such as hydroformingor cata
tained when the per cent of ortho xylene under
going reaction (conversion) was about 40%. This
gave a selectivity of about 98. By selectivity is
lytic cracking, and the Xprocessis particularly
designed for use in combination with a catalytic
meant the percentage of ortho xylene converted
.togmeta and para xylenes and ethyl benzene.
crackingvoperation since the same type of cata
lyst may beused in both operations at substan
tially thesazme temperatures and
However, the utilityv of the invention includes the '
‘formation. of lower ‘boiling aromatics such as
single or
common regenerator may be employed in the ?uid
toluene or‘ethylbenzene, vthe concentration of
catalyst technique common for both the catalytic
which is. much, greater when higher conversion
cracking operation andthe'isomerization reac
' leveIsare employed, The'pl'oducts need not be
tion, the regenerated catalyst being fed, to each
segregated into their'respective constituents since
of the two units (from acommon source and the
spent catalyst ‘from eachof ‘the two units being
fed toa common regenerator for treatment with
.15
air or other free-oxygen-contaim'ng gas as here
practically all of them have excellent blending
values for usein aviation fuels or in safety fuels.
:. .
.
Weight per eent Weight per cent Weight per cent
Weight per cent
total liquid
gas ‘
coke '
conversion
vtofore described.
The syntheticalmnina-silica catalyst may be
employed not only in the form ofv granules of
highly ~porous structure but it may be ?rst pilled
with“ graphite or starch and'regenerated to render
it even more highly porous, or. the catalyst may
6
The purest product. so far as the production
20
be pilled with. graphite orstarch’and used ,fresh
,in the [an-stream operation without ?rst regener
ating the same, although it is preferred .to re
generate the catalyst if in the pilling operation
eithergraphite or starch has been added as a
cohesion agent.
900° F. 975° F. 900° F. 975°F. 900°F. 975°F.
racems
.05
.1
-z
.1
2
0.
'0.
0.
l.
While :higher gas yields are obtained at the
higher temperatures, the total liquid recovery is
excellent in the entire temperature range shown.
A series of experimental runs were made to de- '* The coke formation was so lowthat it was dif
?cult to determine whether the indicated inde
'termine the reaction variables employed from I
pendence of temperature level was real or was '
which a number of observations can be made. At
'due'
to an experimental error. It was found also
a given throughput the. temperaturemaintained
that not’ only did the selectivity decrease with
increasing conversion but that this was not af
fected by the temperature of the operation, the
in the reaction zone has a pronounced effect on
the conversion. For example, by increasing the
temperature from 750° F. to 975°F. while main
taining 0.6 liquid volume of ‘feed. per” volume of
catalyst per hour the conversion was increased
from 44% of the ortho xylene to 77% thereof.
length of time of ion-stream. operation ‘of the
catalystor-thé. throughput of.ther feed» stock '
through the catalyst mass.
illustrated injithe following table:
C8 aromatic fraction having a boiling range of
290-293" F. and of the heretofore-speci?ed com
position through a closed reaction tube ?lled with
about 200 cc. of analumina-silica catalyst whose
composition was, roughly, 87.5 weight per cent
usilicaand 12.5 weight percent alumina. The
products were condensed and collected, theprod
Weight 'per cent conver
sion at the indicated
am"),
- ‘ .? 7:
feeld. rate‘
‘
~ I
_
0.5‘ 1.8 _ ‘at 1140
52.5
The experimental
?ndings were obtained bypassing the vapor of a
not analyzed for constituents rangingin boiling‘
________________ __
50
t2 , 52.5
point between about 265° F. and about 295°. F.
H Arun carried out at 985° F. with a throughput
It‘ is observed that at a given temperature the
lyst perhour forv 12' hours produced a product
’-_ 79'
58
70
57.5
or‘ 0.6.liquid volume of feed per volumeof cata
containing 4 weight percent ethyl benzene, 16
conversion decreases with increasing feed rate.
weight per cent para xylene, 49 weight per cent
Thus, at 1000° F. the conversion drops from 79%
to 52.5%, while the liquid volume of feed stock
per volume of catalyst per hour is increased from
0.6 to 4.0. In general, if reaction occurs, the
meta xylene and 26 weight per cent unconverted
ortho xylene. The yield of the product was about
755% based on the feed stock, with 12%1of the
' product in the benzene range and 3% accounted
?nal product in connection with the isomeriza
for by gas and coke produced.
tion and disproportionation of ortho xylene has
the following weight per cent composition:
Weight per cent
34
Ortho xylene
Meta xylene
A considerable number of experimental runs
were carried out on two-hour reaction periods
using a ?xed bed of 200 cc. capacity through
/
‘which the heretofore speci?cally mentioned feed
49
Para xylene
l2
5 65
Ethyl benzene '
The feed stock employed in this particular
series of runs had the following‘ composition:
stock was passed in the vapor phase. The prod
ucts obtained varied in composition but gen
erally ranged within the following composition:
,
Weight
'
Per cent
Ortho xylene _________________________ __ 26-42
7
Weight per cent
Ethyl benzene _____________________ .__
0
Para xylene _____________ _; ______ __‘__
Meta xylene ______________________ __
0-1
6.5-7
Ortho xylene ______________________ _;
84-87.5
Total aromatics g __________________ __
91-95
70 Meta Xylene
31-49 I
Para xylene _____________ s. ___________ __
3-17
Ethyl benzene ________________________ __
0-5
Total aromatics produced _____________ __ 93-97
The particular percentage of constituents in the
?nal product as heretofore mentioned varies con
2,403,757
7
siderably depending upon the specific reaction
conditions employed, but in general the product
obtained will vary within the heretofore-men
tioned ranges. The product may be isolated
through fractional distillation means ‘or it may
be ‘employed in the form produced directly as a
blending agent in aviation or safety fuels. Ap
preciable amounts of benzene and toluene were
obtained where temperatures in the vupper ‘range
or the heretofore-mentioned temperature ranges
were employed with relatively ‘low rates of
throughput. Thus, ‘for example, when employ»
ing 0.6 volume ‘of feed stock per volume of catalyst
per hour while maintaining a temperature of
1025° F. the result was the production of from
group consisting of boron oxide, thoria, zirconia
and magnesia.
4. A process which comprises isomerizing a feed
stock comprising ‘essentially ortho ‘xylene at a
temperature of about 985° F. at a throughput of
about 0.6 liquid volume of feed per volume of
catalyst per hour while in contact with a catalyst
of silica gel containing alumina and at least one
oxide taken from the group consisting of boron
oxide, thoria, zirconia and magnesia.
’
5. A process as in claim 4 wherein the vfeed
stock is a Ca aromatic fraction obtained from a
catalytic cracking of a petroleum oil.
6. A process as in claim 4'wherein the feed
stock is a Ca aromatic fraction obtained from the
hydroforming of ya petroleum fraction.
20% to 23% of toluene out based on the ortho
'7. A process for the production of meta and
'xylene fed to the reaction zone. The same’ run
para xylene which comprises contacting a feed
produced, on the same basis, from 3.5% to ‘6%
stock comprising‘ essentially ortho ‘xylene vat a
of a benzene fraction. 'In a commercial opera
temperature
between about 750° F. and about
20
tion, however, ‘the use of a temperature of this
1025“ F. a-ta throughput of between about 0.6 and
order would call for the use of a throughput of
about 4.0 liquid volumes of feed stock per volume
from 3 to 3%; liquid volumes of feed stock per
of catalyst per hour with a catalyst comprising
volume of catalyst per hour if it were desired to
essentially synthetic alumina-silica gel, contain
obtain as high a yield as possible of the meta and
25 ing at least one oxide taken “from the group ‘con
para xylenes.
'
sisting of boron oxide, thoria, zirconia and mag
Having thus described and illustrated the
nesia.
nature of the invention, what is desired to be
8. A process as in claim '7 wherein ‘the catalyst
secured by Letters Patent is:
mass is employed in the reaction for a period of
1. .A'prooess for the isomerization vof ortho di
alkyl benzenes which comprises contacting a feed 30 time between about \6 and about 12 hours and
stock comprising essentially said ortho substituted
dialkyl benzenes at a temperature between about
500° F. and about 1100“ F. with a catalyst mass
regenerated with a gas containing free or uncom
bined oxygen for between about 2 and about 3
hours prior to being re-employed for activating
the isomerization reaction, and so employing said
comprising a synthetic alumina-silica gel for -'a
regenerated catalyst.
.
35
suf?cient length of time to form substantial
9. A process for the production of 'meta and
amounts of meta and para isomers, said gel conpara-dialkyl benzenes which comprises contacting
taining at least one oxide taken ‘from the group
a feed stock comprising essentially the corre
consisting of boron oxide, thoria, zirconia and
sponding ortho dialkyl benzenes at a temperature
‘magnesia.
2. In a process of catalytically isomerizing 1,2 40 between about 750° F. and about 1025*’ F. ‘at ‘a
throughput of between about 0.6 and about 4.0
dialkyl benzenes to form the corresponding 1,3
liquid volumes of feed stock per volume of catalyst
and 1,4 dialkyl benzenes under isomerization re
mass ‘per hour with a, catalyst comprising es
action conditions, the ‘improvement comprising
catalyzing the said reaction ‘with a, catalyst mass
sentially synthetic alumina-silica gel, containing
comprising a synthetic alumina-silica gel, con 45 at least one oxide taken from the group consist
ing of boron oxide, thoria, zirconia and magnesia.
taining at least one oxide taken vfrom the group
10. A process as in claim 9 wherein the catalyst
consisting of boron oxide, ‘thoria, zirconia ‘and
magnesia.
3. A process which comprises isomerizing ortho
xylene at a temperature between about 500° ‘F.
and about 1'100° F‘. at a throughput of between
about 0.4 and about 6.0 liquid volumes of ortho
xylene per volume of catalyst mass per hour while
in contact with ‘a synthetic alumina-silica mixed
gel, containing at least one oxide taken from'the 55
mass is employed in the reaction for a, period of
time between about 6 and about 12 hours and re
generated with a gas containing free or uncom
bined oxygen for between about 2 and about 3
hours prior to being re-employed for, activating
the isomerization reaction, and so employing said
regenerated catalyst.
EDWARD D. REEVES.
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