Note: Descriptions are shown in the official language in which they were submitted.
Crystalline aluminosilicates, or zeolites, of which mordenite is
one example, are well known in the art and have found extensive application
as hydrocarbon conversion catalysts or as a component thereof. Such mate-
rials are of ordered crystalline structure often visualized as a three-
dimensional network of fundamental structural units consisting of silicon-
centered SiO4 and aluminum-centered A10~ tetrahedra, the tetrahedra being
interconnected by a mutual sharing oF apical oxygen atoms and arranged to
form cages or cavities in open communication through smaller intracrystalline
channels or pore openings whose narrowest cross section has essentially a
un1form diameter characteristic of each crystalline aluminosilicate variety.
To effect a chem1cal balance, each A104 tetrahedra has a cation associated
therewith -- usually a sodium or other exchangeàble cation. The aforemen-
tioned cages or cavities are occupied by water molecules and by the last
mentioned cations, both of which exhibit considerable freedom of movement
permitting ion-exchange and reversable dehydration.
The crystalline aluminosilicates, or zeolites, employed in the
manufacture of the catalytic composite of this invention, are of the mor-
denite crystal structure, highly siliceous in nature and generally charac-
terized by a siliGa-alumina mole ratio of from about 6 to about 12 as found
in nature. The mordenite crystal structure comprises four- and five-membered
rings of the SiO~ and A104 tetrahedra so arranged that the crystal lattice
comprises pores and channels running parallel along the crystal axis to give
a tubular con~iguration. This structure is unique among the crystalline
aluminosilicates since the channels or tubes do not intersectS and access
to the cages or cavities is in only one direction. For this reason, the
mordenite structure is Frequently re-ferred to as two-dimensional. This
is in contrast to other well-known crystalline aluminosilicates, for example
Faujasite, in which the cavities can be entered from three directions.
Mordenite, clinoptilolite, or mordenite which has been synthesized or acid
extracted, caustic extracted, or otherwise treated to increase the silica-
alumina mole ratio to about 20:1 or more while maintaining the mordenite
crystal structure, may be used in the manufacture of the catalytic composite
of this invention.
Crystalline aluminosilicates having a mordenite crystal structure
have heretofore been utilized composited with a refractory inorganic oxide,
typically alumina, as a hydrocarbon conversion catalyst, and are particularly
useful with respect to the transalkylation of alkylaromatic hydrocarbons.
It is an object of this invention to present a new and useful method of
manu~acture provlding a catalytic composite of improved activity.
In one of its broad aspects, the present invention embodies a
method of manufacture which comprises subjécting a zeolite of the ~ordenite
crystal structure and containlng less than about 5 wt. % sodium as Na20,
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to an aqueous ammoniacal trea-tment at a pH of at least about 9.5, and cal-
cining the thus treated zeolite in intimate admixture with a refractory
inorganic oxide to form a catalytic composite therwith.
One of the more specific embodiments relates to a method of
manufacture providing a catalytic composite of improved activity which
comprises subjecting a zeolite of the mordenite crystal structure contain-
ing less than about 5 wt. % sodium as Na20, to an aqueous ammoniacal treat-
ment at a pH of From about 10 to about 12, and calcining the thus treated
zeolite in intimate admixture with alumina to form a catalytic composite
therewith.
A still more specific embodiment is in a method of manufacture
which comprises subjecting mordenite, containing less than about 5 wt. %
sodium as Na20, to an aqueous ammoniacal treatment with a pH of from about
10 to about 12 and at a temperature of from about 75 to about 200C. in
intimate admixture with alpha-alumina monohydrate, and calcining said
zeolite in intimate admixture with said alumina to form a catalytic
composite therewith.
Other objects and embodiments of this invention will become
apparent in the following detailed specification.
Pursuant to the present invention, the zeolite is subjected to
an aqueous ammoniacal treatment at a pH of at least about 9.5, and said
treatment can be prior to admixture with the refractory inorganic oxide or
after admixture therewith, the latter being preFerred. The aqueous ammoniacal
treatment can be efferted at a temperature of From about 75 to about 200C.
over a period of from about 1 to about 24 hours. The treatment can be
eFfected at subskantially atmospheric pressure in an open vessel at about
the reflux temperature of the aqueous ammoniacal solution albeit over a
more extended period up to about 24 hours. The treatment is effective
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over a substantially shorter period, say from about 1 to about 10 hours at
autogenous pressures utilizing a closed vessel. Switable ammoniacal solu-
tions include solutions of bases such as ammonium hydroxide, hydroxylamine,
hydrazine, tetramethylammonium hydroxide, etc., or strong organic amines
like methylamine 9 dimethylamine, ethylamine, diethylamine, propylamine,
diisopropylamine, n-butylamine, t-butylamine, diisobutylarnine, n-amylamine,
n-hexylamine, ethylene diamine, hexamethylenediamine, benzylamine, aniline,
piperazine, piperadine, and the like, the selected base being employed in
sufficient concentration to provide a pH of at least about 9.5, and
preferably from about 10 to about 12.
The crystalline aluminosilicate, or zeolite, employed herein as
a starting material should contain, or should be treated to contain, less
than about 5 wt. % sodium as Na20. The sodium can be reduced to an
acceptable level by conventional and widely practiced ion-exchange tech-
niques. Typically, ammonium cations are exchanged for sodium cations ontreating the zeolite in contact with an aqueous ammonium salt solution, for
example an aqueous ammonium chloride solution. The resulting anlmonium-
exchanged zeolite is thereafter heat-treated to effect thermal decomposition
of the ammonium cations and formation of the hydrogen form of the zeolite.
In any case, the treatment may be e~fected one or more times to reduce the
sodium content to less than about 5 wt. % as Na20.
Refractory inorganic oxides for use in accordance with the method
of this invention include the naturally occurring as well as the synthetically
prepared refractory inorganic oxides. Suitable refractory inorganic oxides
are such as alumina, silica, ~irconia, titania, thoria, boria, magnesia,
chromia, stannic oxide, and the like, as well as combinations and composites
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thereof, for example~ alumina~si:lica, alumina-zircon:ia,
alumina-tita3lia, etc. Alumina is a preferred refractoxy
inorganic oxide for use herein, particularly with respec-t ~o
the manufacture of a catalytic composite for use in the trans~
alkylation of alkylaromatic hydroca.rbons. The alumina may be
any of the various hydrous aluminum oxides such as alpha-
alumina monohydrate of the boehmite structure, alpha~alwnina
trihydrate oE the gibbsite structure, ~eta-alumina trihydrate
of the bayerite structure, and the like, the first mentioned
alpha alumina monohydrate being preferred.
The zeolite may be combined in intimate admixture
with the refractory inorganic oxide in any conventional or
otherwise convenient manner. For example, the zeolite can he
admixed with an alumina precursor subsequently converted to
alumina to provide the zeolite in intimate admixture with the
aluminaO One preferred alumina precursor for use in this
manner is a basic aluminum sul:Eate such as is precipitated
from an aqueous solution of aluminum sulfate and ammonium
hydroxide at a pH of about 6.
The zeolite may be combined in intimate admixture
with refractory inorganic oxi.de in any conventional or otherwise
convenient manner to form spheres, pills, pellets, granules,
extrudates, or other suitable particle shape. ~ more preferred
method comprises commingling
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the zeolite wlth a powdered refractory inorganic oxide, adding a binder
and/or lubricant to the mixture, and compressing the mixt:ure into pills or
pellets of uniform size and shape. Alternatively, and still more preferably,
the zeolite is mulled with a powdered form of the refractory inorganic
oxide, and with a peptizing agent such as nitric acid, to form an extrudable
dough. The dough can be pressured through a die of predetermined size
to form extrudate particles utilized as such or rolled into spheres in a
spinning drum prior to calcination. In any case, the zeolite can be sub-
jected to the aqueous ammoniacal treatment herein contemplated either before
bein~ admixed with the refractory inorganic oxide or after being ad~ixed
therewith, the latter being preFerred. The zeolite is preferably calcined
in intimate admixture with the selected refractory inorganic oxide in a
weight ratio of from about 1:3 to about 3:1.
Regardless of whether the zeolite is subjected to the aqueous
ammoniacal treatment before or after admixture with refractory inorganic
oxide, the treated zeolite is calcined in intimate admixture therewith to
form a catalytic composite. Calcination is suitably in an air atmosphere
at a temperature of from about 425 to about 750C., preferably at a tem-
perature of from about 475 to about 550C.9 over a period of from about
0.5 to about lO hours.
The catalytic composite of this inYention is particularly useful
for the transalkylation of alkylaromatic hydrocarbons. Thus, an alkyl-
aromatic hydrocarbon having from about 7 to about 15 carbon atoms per
molecule is treated at transalkylation conditions including a temperature
of from about 200 to about 480 C. and a pressure of from about atmospher~c
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to about 1500 pounds per square inch gauge (psig) in contact with a
catalyst comprising essentially the cataly-tic composite of this invention
to form products of higher and lower number of carbon atoms than said alkyl-
aromatic hydrocarbon. The preferred composition employed as the catalytic
composite comprises mordenite in admixture with alumina, said mordenite
comprising from about 25 to about 75 wt. % of said composite.
The alkylaromatic hydrocarbon feed stock can be a substantially
pure alkylaromatic hydrocarbon of from about 7 to about 15 carbon atoms,
a mixture of such alkylaromatic hydrocarbons, or a hydrocarbon fraction
rich in said alkylaromatics. Suitable alkylaromatic hydrocarbons include
alkylbenzenes and alkylnaphthalenes, preferably with an alkyl group oF
less than about 4 carbon atoms. The catalytic composite is particularly
effective in the treatment of the more difficultly transalkylatable toluene
to form benzene, xylenes, or other polymethylbenzenes.
The transalkylation, or disproportionation, reaction can be
effected in contact with the catalytic composite of this invention in any
conventional or otherwise convenient manner and may comprise a batch or
continuous type of operation. A preferred type of operation is of the
continuous type. For example, the above described catalyst is disposed
in a fixed bed in a reaction zone of a vertical tubular reactor and the
alkylaromatic feed stock charged in an upflow or downflow manner, the
reaction zone being maintained at a temperature of from about 200~ to
about 480~ C., preferably at a temperature of from about 220 to about
460 C. Although pressure doés not appear to be an important variable
with respect to the transalkylation reaction of this invention, the pro-
cess is generally conducted in the presence of an imposed hydrogen pressure
to provide from about 1 to about 10 moles of hydrogen per mole of hydrocarbon.
However, there is no net consumption of hydrogen in the process, and the
hydrogen charge is recovered from the reactor effluent and recycled.
The transalkylation reaction can be effected over a wide range of
space velocities. In general, the process is conducted at a space velocity
of from about 0.2 to about 10. Space velocities herein re-ferred to are
liquid hourly space velocities, (L~ISV) i.e., volume of charge per volurne
of catalyst per hour. While the catalytic composite prepared by the
present method permits unusually high space velocities indicative of high
activity, the catalytic composite is particularly note~orthy because of
its relatively high stability at a high activity level.
The composite prepared in accordance with the method of this
invention may be employed as a component of a catalyst comprising any of
the several catalytically active metallic materials in the oxidized or
reduced state. Of particular interest are those catalytic composites com-
prising one or more metals of Group VIB and VIII including molybdenum,
tungsten, chromium, iron, nickel, cobalt, platinum, palladium, ruthenium9
rhodium, osmium and iridium. Thus, the composite of this invention can be
utilized advantageously as a catalyst or component thereof to effect a
variety of hydrocarbon conversion reactions involving reaction conditions
comprising a temperature in the 25-760C. range. The catalysts are particu-
larly useful in effecting the hydrocracking of heavy oils, including vacuum
residuals, to form petroleum products in the middle distillate range uti-
llzing a temperature of from about 260 to about 1560C. and pressures of
from about 500 to about 1000 psig. Said~hydrocarbon conversion reactions
further include polymerization of olefins, particularly ethylene, propylene~
l-butene, 2-butene, isobutylene and also higher boiling olefins, at
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polymerization reaction conditions. The composite of this invention is
also useful as a catalyst or component thereof in effecting the alkylation
of isoparaffins with olefins or other alkylating agents including, for
example, alkyl halides and -the like; and also the alkylation of isobutane,
isopentane, and/or isohexane with ethylene, propylene, l-butene, etc., or
mixtures thereof; and also the alkylation of aromatics with olefins or
other alkylating agents, particularly the alkylation of benzene, toluene,
etc., with propylene, butylene, and higher boiling olefins, including
nonenes, decenes, undecenes, etc., the foregoing alkylation reactions being
effected at alkylation conditions disclosed in the art. The composite of
this invention is further useful in the -isomerization of paraffins, par-
ticularly n-butane, n-pentane, n-hexane, n-heptane, n-octane, etc., or
mixtures thereof, including isomerization of less highly branched chain
saturated hydrocarbons to more hi~hly branched chain saturated hydrocarbons
such as the isomerization of 2- or 3-methyl pentane to 2,2- and 2,3-dimethyl-
butane, isomerization of naphthenes, for examples the iso~erization of
dimethylcyclopentane to methylcyclohexane, isomerization of methylcyclo-
pentane to cyclohexane, etc., at isomerization reaction conditions. Other
hydrocarbon conversion reactions including the reforming of naphtha to
gasoline, dehydroyenation of ethylbenzene to styrene, and hydrogenation of
benzene to cyclohexane, are effectively catalyzed utilizing the composite
of this lnvention as a catalyst or as a component thereof.
The following examples are presented in illustration of the method
of this invention and are not intended as an undue limitation on the gen-
erally broad scope of the invention as set out in the appended~claims.
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EXAMPLE I
In this example, a catalytic composite of mordenite and alumina
was prepared without the benefit of the a4ueous am~oniacal trea1nnent herein
described. Thus, 595 grams of a commercial mordenite (H Zeolon) containing
about 0.16 wt. % sodium as Na20 and 16 wt. ~ volatile matter, as evidenced
by weight loss on ignition at 900C., was thoroughly dry-mixed with 694
grams of a commercial alpha-alumina monohydrate (Kaiser medium) containing
about 28Y3 volatile matter. Approximately 20 milliliters of concentrated
nitric acid and 420 milliliters of water was admixed therewith, and the
mixture mulled to form an extrudable dough. The resulting dough was ex-
truded through a 1/16 inch die and the extrudate segmented and balled in
a spinning drum with the formation of 1/16-1/8 inch spheroidal particles.
The spheroiclal product was subsequently calcilled in air at 500C. for 1 hour.
EXAMPLE II
The preparation was repeated in accordance with the method of
Example I except that the mordenite was subjected to an aqueous ammoniacal
treatment and calcined in intimate admixture with the alumina, the aqueous
ammoniacal trPatment in this case being after admixture with the alumina
pursuant to one preferred embodiment of this invention. In this instance,
the spheroidal product oF Example I was immersed in an aqueous solution of
ammonium hydroxide containing 5 wt. % NH3 and having a pH oF about 11.6.
Five volumes of the aqueous ammoniacal solution were employed per volume
of spheroidal product treated. The treatment was at atmospheric pressure
conditions utilizing a glass flask with an overhead condenser. The treat-
ment was effected at reflux temperature -~ about 90C. 9 over a 16 hour
period. The thus treated material was subsequently water-washed, dried,
and calcined for 1 hour at 500C.
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EXAMPLE III
The preparation of Example I was again repeated except that the
mordenite was subjected to an aqueous ammoniacal treatment and calcined in
intimate admixture with the a1umina, the aqueous ammoniacal treatment in
this case being after admixture with the alumina and at an elevated pres-
sure pursuant to one preferred embodiment of this invention. In this
instance, the spheroidal product of Example I was sealed in a glass-lined
rotating autoclave together with an aqueous ammoniacal solution substan-
tially as described in Example II. The aqueous ammoniacal solution was
employed in an amount equivalent to 2 volumes per volume oF said spheroidal
product. The autoclave was heated to 110C. and the spheroidal product
treated at this temperature under autogenous pressure conditions for 2
hours. The thus treated product was recovered, water-washed, dried and
calcined at 500C. ~or 1 hour.
The above-described preparations were evaluated with respect to
the transalkylation of toluene. In each case, toluene, in admixture with
hydrogen to provide a hydrogen/hydrocarbon mole ratio of about 10, was
charged downflow through a 50 cubic centimeter bed of approximately 1~8
inch spheroidal catalyst particles ak a liquid hourly space velocity of
2.0, and at transall~ylation conditions including a pressure of 500 ps~g.
The temperature of the catalyst bed was adjusted to effect a 40% conversion
of a toluene feed stoc~, the temperature in each case being taken as a
measure of catalyst activity.
The catalytic composites of Examples I, II and III required tem-
peratures of 475, 3~1 and 368C., respectively~ the latter two being
prepared according to the method of this invention.
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EXAMPLE IV
The preparation of Example I was again repeated except that the
mordenite therein described was subjected to an aqueous ammoniacal treat-
ment prior to admixture with the alumina, the mordenite being subsequently
calcined in intimate admixture with the alumina. In this example, the
mordenite was first immersed in the aqueous ammoniacal solution of Example
II. Five volumes of solution were employed per volume of mordenite. The
aqueous ammoniacal treatment was effected under reflux conditions utilizing
a glass flask equipped with an overhead condenser. The treatment was
effected over a 16 hour period at substantially atmospheric pressure con-
ditions, after which the mordenite was recovered and dried. The mordenite
was thereafter thoroughly dry-mixed with the alpha-alumina monohydrate to
provide a 50-50 weight mixture with 20 milliliters of concentrated nitric
acid in 420 milliliters of water being subsequently added. After thorough
mulling to provide an extrudable dough, the dough was extruded, segmented,
and formed into spheres as heretofore described. The spheroidal product
was calcined in air for 1 hour at 500C. and thereafter evaluated with
respect to the transalkylation of toluene in the described manner. A 40~
conversion was achieved at 380C.
EXAMPLE V
In this example, the mordenite employed was an ammonium iun-exchanged
mordenite as opposed to the aqueous ammoniacal solution-treated mordenite
of this invention. Thus, a solution of 260 grams of ammonium nitrate in
2340 cubic centimeters of water was used to a~monium ion-exchange 600 grams
of the mordenite. The mordenite was slurried in 600 cc portions of the solu-
; tion at about 55C. for about 1/2 hour, the mordenite being recovered by
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filtration after each of three such anlmonium ion-exchange treatments. After
the final treatment the mordenite was dried at about 950e. The mordenite
was thereafter thoroughly dry-mixed with the alpha-alum'lna monohydrate to
provide a 50-50 weight mixture with 20 milliliters of concentrated nitric
acid in 420 milliliters of water being subsequently added. After thorough
mulling to provide an extrudable dough, the dough was extruded, segmented
and ~ormed into spheres as heretofore described. The spheroidal product
was calcined in air for 1 hour at 500C., and thereafter evaluated with
respect to the transalkylation of toluene in the described manner. A 40%
conversion was achieved at 463C.
EXAMPLE VI
A substantially pure rnordenite (H Zeolonj, in the form of extrudate
particles was calcined in air for 1 hour at 500C. and thereafter eYaluated
with respect to the transalkylation of toluene in the described manner. In
this instance, a temperature of 508C. was required to achieve a 40% con-
version. In a separate experiment, the calcined extrudate was further
treated with an aqueous ammoniacal solution substantially in accordance
with the method of Example III9 and then further calcined in air at 500C.
for 1 hour. Although the temperature requ;red to effect a 40% conversion
of toluene was reduced to 473C., the temperature is substantially higher
than that required when the treated mordenite is calcined in intimate
admixture with aluminaO
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