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Патент USA US3079456

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erally about 10 or 25 to 100% by weight of naphthenes,
preferably about 50 to 95% by weight, are in the reac
tion product. In the second stage of the invention the
isomerized naphthenes are dehydrogenated to aromatics.
Our hydrocarbon conversion catalyst for the ?rst stage
Patented Feb. 25, 1953»
-PLA ‘1
Ronald S. Bartlett, Thornton, Glenn 0. Michaels, Park
Forest, and Owen H. Thomas, Bolton, 111., assignors,
by mesne assignments, to Sinclair Research, Inc., New
York, N.Y., a corporation of Delaware
No Drawing. Filed dune 13, 1960, Ser. No. 35,423
6 Claims. (Cl. 269-668)
This invention relates to a process for the isomeriza
tion of alkyl aromatics.
Alkyl aromatic isomerization reactions can usually be
includes catalytically etfective amounts of a noble or
platinum group metal and boria supported on an alumina
base. The catalyst generally contains about 0.05 to 2
weight percent, preferably 0.1 to 1 weight percent, of
10 one or more of the platinum metals of group VIII e.g.
platinum, palladium, rhodium, ruthenium, osmium or
iridium, with the metals having face centered cubes being
preferred. The small amount of noble metal may be
divided into at least two distinct types. One type involves
present in the metallic form or as a sul?de, oxide or
the migration of an alkyl group around the aromatic ring 15 other combined form. The metal may interact with
as in the conversion of isodurene to durene. This type
other constituents of the catalyst, but if during use the
of reaction presumably does not involve rupture of the
noble metal be present in metallic form then it is pre
bonds within the ring and it usually proceeds rapidly
ferred that it be so ?nely divided that it is not detectable
without too much di?iculty. Another type of isomeriza
by X-ray diffraction means, i.e. that it exists as crystals
tion involves the conversion of ethyl, propyl and higher 20 of less than about 50 Angstrom units size. Of the noble
alkyl groups on the ring into methyl-substituted aromatics
metals platinum, palladium and rhodium are used most
or into aromatics having side chains with fewer carbon
atoms. This type of reaction presumably involves a ring
The boria component is surface dispersible on the sup
expansion-contraction mechanism and is usually much
port. It is employed in amounts su?icient to enhance the
slower than the migration of alkyl groups around the 25 acidity of the alumina support and such amounts are,
ring. In particular, as the number of carbon atoms in
therefore, preferably added in direct proportion to the
the side chain increases, there is a greater tendency for
area of the support. For instance, the amount of boria
the alkyl groups to split off (dealkylate) from the arc
will usually be about 0.5 to 20 weight percent, and prefer
matic ring forming lower molecular weight aromatics and
ably about 5 to 15 weight percent, of the catalyst. These
cracked products. Thus, isomerizations of this latter type 30 amounts are particularly e?ective on aluminas having
generally demonstrate a relatively poor selectivity to the
‘surface areas of about 350 to 600 square meters per gram
methyl-substituted aromatics of the same molecular
weight as the alkyl aromatic isomerized.
We have now discovered a two-stage process for in
(BET) before use.
The noble metal and boria constituents of the catalyst
are deposited on an absorptive alumina base of the ac
creasing the selectivity of the isomerization reaction of 35 tivated or calcined type. The base is usually the major
certain alkyl aromatics to methyl-substituted aromatics.
component of the catalyst, generally constituting at least
According to the present invention a benzene aromatic
hydrocarbon in the C8 to C12 range preferably in the C9
about 75 weight percent on the basis of the catalyst,
preferably at least about 80 to 90%. The catalyst base
to C10 range, having one or more alkyl groups of 2 or
is an activated or gamma-alumina such as those derived
more carbon atoms, preferably 3 or more carbon atoms, 40 by calcination of amorphous hydrous alumina, alumina
in length, attached to the aromatic ring is ?rst contacted
monohydrate, alumina trihydrate or their mixtures. The
under vapor phase isomerization conditions and in the
catalyst base precursor most advantageously is a mixture
presence of free hydrogen with a catalyst consisting essen
predominating, for instance about 65 to 95 weight per
tially of alumina and catalytic amounts of boria and a
cent, in one or more of the alumina trihydrates, bayerite
platinum group metal. In the second stage of the present 45 ‘I, bayerite II (randomite or nordstrandite) or gibbsite,
and about 5 to 35 weight percent of alumina mono
invention, isomerized product from the first stage is de
hydrogenated in the presence of a dehydrogenation
hydrate (-boehmite), amorphous'hydrous alumina or their
catalyst under dehydrogenation conditions to obtain a
mixture. The alumina base can contain small amounts
product which is mostly or even substantially entirely
of other solid oxides such as silica, magnesia, natural or
activated clays (such as kaolinite, mcntmorillontrite, hal
The isomerization reaction conditions of the ?rst step
loysite, etc.), titania, zirconia, etc., or their mixtures.
in the present invention include a temperature su?icient
to maintain the alkyl aromatic feed in the vapor phase
Although the components of the catalyst can vary as
stated. a preferred catalyst contains platinum and boria
under the pressure employed. Generally this tempera 55 deposited on activated alumina at least about 200 square
meters per gram surface area before use.
As previously stated the preferred catalyst base ma
terial is an activated or gamma-alumina made by calcining
superatmospheric, for instance, ranging from about 50 to
a precursor predominating in alumina trihydrate. An
2000 p.s.i.g., preferably about 300 to 600 p.s.i.g. The
alumina of this type is disclosed in US. Patent No.
catalyst can be used as a ?xed, moving or ?uidized bed
ture will be from about 500 to 740 or 750° F., prefer
ably about 550 to 650° F., while the pressure will be
or in any other convenient type of handling system. The
?xed bed system seems most advantageous at this time
and the weight hourly space velocity will in most cases
be from about 0.25 to 50, preferably about 1 to 10. Free
molecular hydrogen must be present in our reaction sys
tem and the hydrogen to alkyl aromatic molar ratio will
usually be from about 1 to 20:1 or more, preferably about
4 to 12:1. In this stage of the present invention, gen
60 2,838,444.
The alumina base is derived from a precursor
alumina hydrate composition containing about 65 to 95
Weight percent of one or more of the alumina trihydrate
forms gibbsite, bayerite I and bayerite ll (randomite or
nordstrandite) as de?ned by X-ray di?raction analysis.
The substantial balance of the hydrate is amorphous
hydrous or monohydrate alumina. Trihydrates are pres
ent as well de?ned crystallites; that is, they are crystal
line in form when examined by X—ray diffraction means.
be employed. Minor catalytic amounts, usually less than
'Ifheicrystallitesize of- the precursor alumina trihydrate
is-relatively- largeandusually the 100 to1000 Ang
about 10% or 20%..and atleast about 0.1% of. these in-,_
gredients can be dispersed on or carried as promoters
strom unit range. The calcined alumina has a large por
tion of its pore volume in the pore size range of about
by solid materials such as charcoal, oxides, silicates or
mixtures or oxides and silicates. Since a dehydrogenation
100 to 1000 Angstrom units generally having about 0.1 to
about 0.5 and preferably about 0.15 to about 0.3 cc./ g.
of pore volume in this range. As described in the patent
the calcined catalyst base can be characterized by large
catalyst which causes little, if any, dealkylation is pre
ferred, the carrier material or support is preferably es
sentially non-acidic. The more acidic the support is, the
less severe should be the dehydrogenation conditions so as
surfaceiarea ranging from about-.350 to about 550 or more
square vmeters/ gram when in the virgin state. as determined,
for? example, . by the BET absorption . technique. A low:
to avoid'dealkylation.‘ The composite-is usually calcined,
or activated after the promoting metal is added. Speci?c
examples of suitable dehydrogenation catalysts arelplati
area catalyst base prepared by treatingthe. predominantly
trihydrate: base precursor. is described in US. Patent-No. ' mom or alumina, platium-on-charcoal, cobalt-molybdena;
on-alumina, nickel-tungsten,oxide-on-alumina,nickel-tung
2,838,445. This base when in the virgin state has sub
stantially no pores of radius less than about 10 Angstrom 15 sten sul?de-on-alumina, cohalt-molybdena-on-silicaaluml
na and palladium-on-charcoal.
units an'dith‘e surface area of the catalyst base is less than
The alkyl aromatic, feed. material employed. in our.
about'350- square meters/ gram and most advantageously is
process is a material that contains as the major fraction a
inthe range of about 150 to 300 square meters/ gram.
C8: to C12 benzene aromatic hydrocarbon. having attached
The platinum group metal component of the. catalyst
canibe added to the alumina base by known=procedures. 20 to its aromatic ring one or more alkylvgroups of at least.
2' carbon: atoms, preferablyv ' off :at_ ‘least. 3 carbon, atoms.
For instance,_the' platinum metal component can1be1de
The preferred: alkyl aromatic feeds arethose. containing
‘as-a major‘ fI'aCtlO?uC/g and- Cm benzene der-ivativesin
positedion alcalcined oractivated-alumina, but’ it is pre
ferreduto, add- the platinum .metal-component-_to the
alumina hydrateprecursor.‘ Thus‘ platinum can‘be. added
throughzreaction of a halogen platinumv acid, for instance,
?uoror, ,ch1oro-,,bromo- or iodo-platinic acid, and-hydro
which at‘ least; one. side chaindslonger- than two carbon
The following . speci?c . examples will serve vto ; illustrate
our invention but. arevnotto be- considered limiting._
gen-sul?de inv an aqueous slurry‘ of thelaluminav hydrate;
The-hydrogen sul?de can beemployedias agas or‘v an aque
oussolution. Alternatively, the platinum component-can
be provided by mixing an aqueous platinum sul?de. sol 30
‘300 grams of'fa calcined platinum-alumina catalyst. of
with the alumina hydrate. This ‘sol can be made by re
the type. described in _U.S. Patent No. 2,838,444’ were
action-in‘ anaqueousrmedium of a halogen'platinic acid
weighed" into a 6" crystallizingdish'. The catalyst‘ an
with hydrogen sul?de. The aluminahydrate containing
alyzed 0.6%, platinum and‘ at the time or platinum‘ addi
the platinum metal canvbe dried‘ and‘calcined usually.- at
a- temperature fromsabout 750 to 1200? Ror more to pro— 35
vide-the activated or gamma-alumina modi?cations. The
boria can. be added tot'he-catalyst in. any stage of its‘prep
ara'tionn‘ It. vmay be incorporated; in the support,,for in
tion. and-,hefore'calcination the, alumina comprised about
70% trihydrate. (42% bayerite, 18%, randomite, 11%
gibbsite). with. the remaining being, substantially, of, the
amorphous. of monohydrate forms. After calcination at- a
stance, by precipitation, coprecipitation,impregnation, and
maximum temperature of about 925 °' ‘F; ' the; catalyst
VIII-metal. ' ltjcan alsobe applied by impregnation from
fromabout 350 to 550 square ‘meters’ pergram. 59
mulling either before or after the addition of’ the group 40 composition had an area (BET method) within the range
solution .(water, organic or inorganic solvents) ‘or from.
atgasphasepf However, it is frequently added to the cata
lyst1afterithasbeen formed by tableting, or extrusion-and
calcined'.. After the boria is added ‘in this procedure-the
grams of. B31303 were dissolved in ‘279ml; of deionized
water by heating to boiling. The hot. boric acid‘ solution
was poured» over the. platinum—alum_ina catalyst‘ and stirred
catalystrcan be recalcined, Preferably, the boria is added
by pouring. a hot vsolution of'boric. acidover the. platinum
alumina catalystystirrin‘g thoroughly, and thendrying and
hours“: Thejcatalystwas stirred. occasionally while drying,
The oven¢dried catalystv was transferred. to a sagger and
placed in a muffle furnace preheated to 1000" F. The
The catalyst of the present. invention can beyearsily
regenerated employingxconvention'al procedures,’ for .in
stance, by subjectingfit. to an‘Voxygen-containing gasat
temperatures su?icient to- burn off carbon deposited on; the
catalyst. during the conversion of- petroleum hydrocarbon
feedstock. This. oxygen-containing gas,.;e.g. an oxygen
ni'trogen mixture, can. contain about 0.01 Weight percent
.to" Sweight. percent oxygenbut preferably contains about
at a rate of 0.5 to 1.0 cubic foot per hour for 3' hours
_ The'dehydro'genation conditions. of the second stageof
‘Examples of suitable catalyst ingredients employed in
to insure. platinum reduction.‘ At this. time ‘feedstock
composed of 1 mole of’ cumene/ 1 mole of diethylbenzene
is passedover the. catalyst from a pump and the. reaction
is. conducted under the conditions, shown in, Table vI.
thepre'sent invention generally employed will ,fall. within
the‘following ranges: temperature, about 600 to 1000°.F,,
:mole' ratio, about 1 to 20:1, preferably about 6 to 12:1.
A 1"’ UniversalStainless Steel reactoris charged with
88,‘ g. (.100 cc.) of a platinum-alumina-boria catalyst pre
pared essentially as above. Hydrogen ?owis maintained
‘?ow Iatesuch that the maximum temperature at the; site
‘preferably about 700 to 900° F.; pressure, atmospheric to
about 600>p.s.i.g., preferably atmospheric to about 200
.p._'s.i.'g.;' weight hourly space velocity, about 0.25 to 20,
preferably about 1 to 10; free hydrogen to hydrocarbon
.catalyst was held, at- 1000° F, 'for' 2. hours, and cooled
ima. desiccator. Analysis 9.95%v B203,
0.5 to 1.5 weight percent oxygen and .is introduced. at a
oflcornbustion is'below about. 1000"‘ .F.
thoroughly with; a rubber spatula.v The ‘catalyst was
placed in a torced
drying even, ‘set. at 284° Fffor 4
Atrthe endzyot a three hour reaction period the runis
terminated and the products removed to a dehydro
genation?zone and contacted ‘with a-platinum-oni-carbon
catalyst at a temperature of 900° F., pressureof 200
p.s.i.g., WHSV of 10 and a hydrogen to hydrocarbon
ratio of 4/ 1. The products from the dehydrogenation
reaction are analyzed by mass spectrograph and infrared.
the dehydrogenation stage are any of the dehydrogenation 70
The results are shown in Table I. For ‘comparative
catalysts such as molybdenum, tungsten, vanadium, tin,
purposes runs of a one’ stage isomerization, process em
chromium, the group VIII metals, for instance, iron, co
balt, nickel, platinum group metals and their oxides, sul
?des and other combined forms. Mixtures of these ma.
ploying the same platinum-boriaalumina catalyst are
shown. The reaction conditions employed in “the
-tlerials or compounds or two or more of the oxides can 75 .are also shown in Table II.
Table I
quite as marked. At 20% conversion of diethylbenzenc,
the selectivity to ethyl Xylene plus tetramethyl bcnzcnes
was 64% in the one-stage process. At 38% conversion,
selectivity dropped to 34% when operating in one stage.
In the two-stage process of the present invention, the
selectivity was 44% at greater than 50% conversion.
The data indicate that selectivity of the isomerization of
{Isomerization Catalyst: 0.6% Pit-10% 13203-111103. Feed: 1 mole of
cumene/l mole of Diethylbenzenc]
One One
stage stage
stage 1
diethylbcnzene decreases rapidly as the conversion in
Isomerization conditions:
Temperature, ° F _______________________ __
Pressure, p.s.i."___
_____ __
8. 4
Hz/HO __________________________ __
Weight percent naphthenes at equil. ____
Overall recovery, weight percent:
creases. It is apparent that the optimum conditions for
10 the conversion ‘of diethylbenzcne are more severe than
are required for the conversion of cumene, so higher over
~17. 5
3. 5
all selectivitics can be obtained if the two types of com
pounds are isomcrizcd in separate reaction zones.
Cn aromatics, weight percent _____ __ 47. 5
Cw aromatics, weight percent ____ _- 52.5
2 21
2 37
91. 6
90. 6
19. 5
37. 7
53. 4
36. 9
9. 3
23. 4
24. 6
20. 6
Conversion of cumene, weight
percent ______________________________ __
Conversion of dietbcnzene, weight
percent ______________________________ __
Selectivity of the conversion of
cumene to trimethyl benzenes,
reight percent _______________________ __
Pure grade curnenc was isomerized in accordance with
the two-stage process of the present invention and also
by a one-stage process. The isomerization catalyst in
both instances was 0.6% Pt, 10% B203 on A1203. The
Selectivity of the conversion of diet
benzene to ethylxylenes, weight
percent ______________________________ __
Selectivity of the conversion of diet
benzene to tetramethylbenzene,
weight percent _______________________ __
dehydrogenation catalyst employed in the second step of
the two-stage process was 0.6% Pt-Al2O3. The re
1 Dehydrogenation catalyst: 0.6% Pt on carbon; 900° F., 200 p.s.i.g., 25
action conditions and results are given in Table II. A
1O WHSV, ~4/1 Hr/HC.
2 Overall recovery from both the isomerization step and the dehydro
comparison of the one-step and two-step processes as to
genetion step.
selectivity is given in Table III.
3 First stage.
Table II
Run number _______________________________ ._
Catalyst ___________________________________ __ Pt-Bzoa-Alzoz lat-A1203
Pt-BzOs-AlzOa Pt-BgO3-AlgO3 Pt-AIQO3
P.G. cumene Prod. from Prod. from P.G. cumenc P.G. cumene Prod. from
Isomerization conditions:
Temperature, ‘‘ F__
................ -_
Pressure, p.s.i.g._
4. 4
s. 0
s. 4
1. 4
1. 9
5. 7
100. 4
89. 4
S9. 4
4. 2
Percent 11 p. at equi ._.
Recovery, weight percent:
Liq. prod ______________________________ __
Dry gas ________ -F.
6.9(3. 1)
VPO analysis of total liquid product:
15. 6
26. 1
18.8 83.6
30. 8(25. 2)
-4. 1
12.0(10. 6)
-4. 0
s2. 4
as. 1
12.5 66.6
17.1 61.4
19.0 72 9
25. s
4s. 0
0. 9
1. 1
46. 3
22. 4
31. 2
54. 9
18. 8
27. 3
2s. 7
0. 5
5. a
0, 4
VPC analysis of normalized Ce fraction:
Cumene _______________________________ -_
Ethyltoluene __________________________ -Trimethylbenzenes ____________________ _-
8. 1
26. 1
65_ 3
1 N aphthenes.
The data demonstrates the advantage of using the two- 65
stage process of the present invention over a one-stage
isomerization process for the conversion of cumcne.
Table III
85-92% conversion of curnene', the selectivity to tri-
One-step Two-step process.
rncthylbcnzenes 15 only 3—9% in the one-stage process
whereas the selectivity to trimethylbenzcnes in the two- 70
stage process of the present invention is about 4 times as
great at the same conversion level.
There is also signi?cant advantage in using the two-stage
Run #54 R1111 #58
Conwrsion ofcumene
86 5
gelec?ivigy £0 btQInZIeneIIIII _______ "
16: 8
t- .
e co ivi y 0 e
y to uene _____ __
process of the present invcntlon
for the isomcrization
_____ __
diethyl substituted aromatics but the dl?crencc is not 75
‘Examination ‘of Table III shows that in the two-stage
platinum group metal, to convert at least about 10% of
process, rtheconversion of curnene to benzene was only
6-7% even at the 95% conversion level. ‘In the one
then dehydrogenating resulting isomerized' product in the
stage process, the degradation of- cumene'to benzene was
overitwice as high at 37%; conversion. Furthermore, the
ation conditions including a temperature of about 600- to
‘the alkyl benzene feed to‘ naphthene hydrocarbon and
presence vof a dehydrogenation catalyst under dehydrogen
selectivity to trir'neth'yl b'enzenes was almost twice as great »
in the-two-stage process as-Vin the one-stage operation.
10 tains 3 carbon atoms.‘
of ; the C9 aromatics was formed.
4. The process :ofclairn 3 wherein the catalyst consists
essentially of ‘alumina, about ‘0.1 to 1 weight ‘percent of a
platinum group metal and about '5 to 15 weight percent
5. The process of claim 4 wherein the platinum group
metal is platinum.
Equilibrium YPO analysis
distribution of C9 product
3. The process of claim 2 wherein the alkyl group con
Run iNo. ‘ ‘993:5 8 shows vthat near. equilibrium distribution
Ethyl toluene _________________________ ._
Trimethylbenzenes ...... -7 ...... -1. ‘.__._
72. The method of claim 1 in which the alkyl benzene
.feed has 9tto 1.0 carbon .atoms.
lA-n examination-of the c9‘ fraction in the product from
1000" F.
at 620° FJ
1 Chemical Thermodynamics Properties of Hydrocarbons. Frederick
Rossini. American Petroleum Institute Research ;Project>No. 454!
6. The process of claim 5 wherein the alumina is de
rived byrcalcination of hydrous alumina containingabout
65 to 95 percent trihydrate and has a surface areaof about
20 ,350 to 550 square meters per gram before use.
References (Iited in the ?le of this patent
We ‘claim: .
1.-- A wastage-process forisomerizins 68 10-012 alkyl
benzene hydrocarbons having at leastone alkyl'groupwn
{raining at least 2,,carbon atomswhich isconverted to a
"methyl-substituent vwhich comprises contacting v.saicl. alkyl
benzene hydrocarbon under [vapor , phase isomerization
conditionsat a temperature of aboutSOO to 750° F. and
in the presence of free hydrogen with acatalyst consisting
essentially of alumina and catalytic amounts of boria and a
2,403,757 r
Reeves _..V_VH,__H_Y_V,._H_,,,,,,____ July 9,1946
Heinemann ___________ __ June 19, 1956
Pitts et al.: “Industrial and Engineering Chemistry,”
vol. 47, pages 770-773, April 1955.
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