Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a process for preparing
alkyl aromatic compounds by alkylating an aromatic compound
with a paraffin alkylating agent employing an alkylation
catalyst comprising synthetic porous crystalline material
from a particular class of materials characterized by an X-
ray powder diffraction pattern including interplanar d-
spacings at 12.36 ~ 0.4, 11.03 ~ 0.2, 8.83 ~ 0.14, 6.18 ~
0.12, 6.00 ~ 0.10, 4.06 ~ 0.07, 3.91 ~ 0.07, and 3.42 ~
0.06 Angstroms.
U.S. Patent Nos. 4,962,256; 4,992,606; 4,954,663;
5,001,295: and 5,043,501, each incorporated herein by
reference in its entirety, teach alkylation of aromatic
compounds with various alkylating agents over catalyst
comprising a particular crystalline material, such as PSH-3
or MCM-22. U.S. Patent No. 4,962,256 describes preparing
long chain alkylaromatic compounds by alkylating an
aromatic compound with a long chain alkylating agent. U.S.
Patent No. 4,992,606 describes preparing short chain
alkylaromatics by alkylating an aromatic compound with a
short chain alkylating agent. U.S. Patent No. 4,954,663
teaches alkylation of phenols, and U.S. Patent No.
5,001,295 teaches alkylation of naphthalene. U.S. Patent
No. 5,043,501 describes preparation of 2,6-
dimethylnaphthalene. The alkylating agents taught for use
in these patents are olefins such as ethylene, propylene,
the butenes, and the pentenes; alcohols (inclusive of
monoalcohols, dialcohols, trialcohols, etc.) such as
methanol, ethanol, the propanols, the butanols, and the
'30 pentanols; aldehydes such as formaldehyde, acetaldehyde,
propionaldehyde, butyraldehyde, and n-valeraldehyde; and
alkyl halides such as methyl chloride, ethyl chloride, the
propyl chlorides, the butyl chlorides, and the pentyl
chlorides, and so forth.
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It is an object of this invention to provide a process
for the alkylation of an aromatic compound with a paraffin
alkylating agent to produce alkyl aromatic product
employing an alkylation catalyst comprising a particular,
porous crystalline material characterized by an X-ray
diffraction pattern including interplanar d-spacings at
12.36 ~ 0.4, 11.03 ~ 0.2, 8.83 ~ 0.14, 6.18 ~ 0.12, 6.00 ~
0.10, 4.06 ~ 0.07, 3.91 ~ 0.07, and 3.42 ~ 0.06 Angstroms.
By way of realizing the foregoing and other objects of
the invention, a process for preparing alkyl aromatic
compounds is provided which comprises contacting at least
one alkylatable aromatic compound with at least one
paraffin alkylating agent under alkylation reaction
conditions and in the presence of an alkylation catalyst to
provide an alkylated aromatic product possessing at least
one alkyl group derived from said paraffin alkylating
agent, said catalyst comprising a synthetic porous
crystalline material characterized by an
X-ray diffraction pattern substantially as set forth
hereinafter.
The term "aromatic" in reference to the alkylatable
compounds which are useful herein is to be understood in
accordance with its art-recognized scope which includes
alkyl substituted and unsubstituted mono- and polynuclear
compounds. Compounds of an aromatic character which
possess a hetero atom are also useful provided they do not
act as catalyst poisons under the reaction conditions
selected.
Substituted aromatic compounds which can be alkylated
herein must possess at least one hydrogen atom directly
bonded to the aromatic nucleus. The aromatic rings can be
substituted with one or more alkyl, aryl, alkaryl, alkoxy,
aryloxy, cycloalkyl, halide, and/or other groups which do
not interfere with the alkylation reaction.
Suitable aromatic hydrocarbons include benzene,
naphthalene, anthracene, naphthacene, perylene, coronene
and phenanthrene.
,.
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Generally the alkyl groups which can be present as
substituents on the aromatic compound contain from one to
about 22 carbon atoms and usually from about one to eight
carbon atoms, and most usually from about one to four
,5 carbon atoms.
Suitable alkyl substituted aromatic compounds include
toluene, xylene, isopropylbenzene, normal propylbenzene,
alpha-methylnaphthalene, ethylbenzene, cumene, mesitylene,
durene, p-cymene, butylbenzene, pseudocumene,
o-diethylbenzene, m-diethylbenzene, p-diethylbenzene,
isoamylbenzene, isohexylbenzene, pentaethylbenzene,
pentamethylbenzene; 1,2,3,4- tetraethylbenzene; 1,2,3,5-
tetramethylbenzene: 1,2,4-triethylbenzene: 1,2,3-
trimethylbenzene, m-butyltoluene; p-butyltoluene; 3,5-
diethyltoluene: o-ethyltoluene; p-ethyltoluene; m-
propyltoluene: 4-ethyl-m-xylene; dimethylnaphthalenes;
ethylnaphthalene; 2,3-dimethylanthracene; 9-
ethylanthracene; 2-methylanthracene; o-methylanthracene;
9,10-dimethylphenanthrene; and 3-methyl-phenanthrene.
Higher molecular weight alkylaromatic hydrocarbons can also
be used as starting materials and include aromatic
hydrocarbons such as are produced by the alkylation of
aromatic hydrocarbons with olefin oligomers. Such products
are frequently referred to in the art as alkylate and
include hexylbenzene, nonylbenzene, dodecylbenzene,
pentadecylbenzene, hexyltoluene, nonyltoluene,
dodecyltoluene, pentadecytoluene, etc. Very often alkylate
is obtained as a high boiling fraction in which the alkyl
group attached to the aromatic nucleus varies in size from
about C6 to about C12.
Reformate containing substantial quantities of
benzene, toluene and/or xylene constitutes a particularly
useful feed for the alkylation process of this invention.
The alkylating agents which are useful in the process
of this invention generally include paraffins having from
about 1 to about 14 carbon atoms, preferably from about 1
to about 8 carbon atoms. Non-limiting examples of suitable
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alkylating agents are propane, butanes, pentanes, hexanes,
heptanes, octanes and mixtures thereof. Branched
alkylating agents, especially isobutane and isopentane, are
also useful herein.
In its calcined form, the synthetic porous crystalline
material component employed in the catalyst composition
used in the process of this invention is characterized by
an X-ray diffraction pattern including the following lines:
......_...._.,..,~"."._ .. .. T.. , ." . ..
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TABLE A
Interplanar d-Snacina fA~ Relative Intensity. I,/Io x
100
12.36 ~ 0.4 M-VS
11.03 0.2 M-S
8.83 0.14 M-VS
6.18 + 0.12 M-VS
6.00 0.10 W-M
4.06 + 0.07 M-S
3.91 0.07 M-VS
3.42 0.06 VS
Alternatively, it may be characterized by an X-ray
diffraction pattern in its calcined form including the
following lines:
TABLE B
Interplanar d-S~acina ~(A~ Relative Intensit,~y., IfIo x
100
30.0 + 2.2 W-M
22.1 + 1.3 W
12.36 ~ 0.4 M-VS
11.03 ~ 0.2 M-S
8.83 ~ 0.14 M-VS
6.18 ~ 0.12 M-VS
6.00 + 0.10 W-M
4.06 + 0.07 M-S
' 3.91 + 0.07 M-VS
3.42 + 0.06 VS
More specifically, the calcined form may be characterized
by an X-ray diffraction pattern including the following
lines:
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TABr E C
Interglanar d-Spacing (Al Rel ati ve Inten~ i t~y., I f o x
100
12.36 0.4 M-VS
11.03 0.2 M-S
8.83 0.14 M-VS
6.86 0.14 W-M
6.18 0.12 M-VS
6.00 0.10 W-M
5.54 0.10 W-M
4.92 0.0g W
4.64 0.08 W
4.41 0.08 W-M
4.25 0.08 W
4.10 0.07 W-S
4.06 0.07 M-S
3.91 0.07 M-VS
3.75 0.06 W-M
3.56 0.06 W-M
3.42 0.06 VS
3.30 0.05 W-M
3.20 0.05 W-M
3.14 0.05 W-M
3.07 0.05 W
2.99 0.05 W
2.82 0.05 W
2.78 0.05 W
2.68 0.05 W
2.59 0.05 W
Most specifically, it may be characterized in its
calcined form by an X-ray diffraction pattern including the
following lines:
._~ ..._.....~..w.~.,.... r ,
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~nter~lanar d-S~acing~ (A~ Relative Intensity. I,Io x
100
30.0 + 2.2 W-M
22.1 + 1.3 W
12.36 + 0.4 M-VS
11.03 0.2 M-S
8.83 + 0.14 M-VS
6.86 + 0.14 W-M
6.18 + 0.12 M-VS
6.00 + 0.10 W-M
5.54 + O.IO W-M
4.92 + 0.09 W
4.64 + 0.08 W
4.41 + 0.08 W-M
4.25 + 0.08 W
4.10 + 0.07 W-S
4.06 + 0.07 M-S
3.91 0.07 M-VS
3.75 + 0.06 W-M
3.56 + 0.06 W-M
3.42 + 0.06 VS
3.30 + 0.05 W-M
3.20 + 0.05 W-M
3.14 + 0.05 W-M
3.07 + 0.05 W
2.99 + 0.05 W
2.82 0.05 W
2.78 + 0.05 W
~30 2.68 0.05 W
2.59 0.05 W
These values were determined by standard techniques.
The radiation was the K-alpha doublet of copper and a
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diffractometer equipped with a scintillation counter and an
associated computer was used. The peak heights, I, and the
positions as a function of 2 theta, where theta is the
Bragg angle, were determined using algorithms on the
computer associated with the diffractometer. From these,
the relative intensities, 100 I/Io, where Io is the
intensity of the strongest line or peak, and d (obs.) the
interplanar spacing in Angstrom units (A), corresponding to
the recorded lines, were determined. In Tables A-D, the
relative intensities are given in terms of the symbols W =
weak, M = medium, S = strong, and VS = very strong. In
terms of intensities, these may be generally designated as
follows:
W = 0-20
M = zo-4a
S = 40-60
VS = 60-100
It should be understood that these X-ray diffraction
patterns are characteristic of all species of the synthetic
porous crystalline material. The sodium form as well as
other cationic forms reveal substantially the same pattern
with some minor shifts in interplanar spacing and variation
in relative intensity. Other minor variations can occur
depending on the ratio of structural components, e.g.,
silicon to aluminum ratio of the particular sample, as well
as its degree of thermal treatment. Examples of such
porous crystalline materials include the PSH-3 composition
of U.S. Patent 4,439,409, and MCM-22 of U.S. Patent
4,954,325.
The synthetic porous crystalline material herein can
also be used in intimate combination with a hydrogenating
component such as tungsten, vanadium, molybdenum, rhenium,
nickel, cobalt, chromium, manganese, or a noble metal such
as platinum or palladium where a hydrogenation-
dehydrogenation function is to be performed. Such
component can be introduced by way of co-crystallization,
exchanged into the material to the extent a Group IIIA
,,
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element, e.g., aluminum, is in the structure, impregnated
therein or intimately physically admixed therewith. Such
component can be impregnated in, or on, the synthetic
porous crystalline material such as, for example, by, in
the case of platinum, treating the material with a solution
containing a platinum metal-containing ion. Thus, suitable
platinum compounds for this purpose include chloroplatinic
acid, platinum halides and various compounds containing the
platinum ammine complex.
The synthetic porous crystalline material for use
herein, especially in its metal, hydrogen and ammonium
forms, can be beneficially converted to another form by
thermal treatment. This thermal treatment is generally
performed by heating one of these forms at a temperature of
at least about 370°C for at least 1 minute and generally
not longer than 20 hours. While subatmospheric pressure
can be employed for the thermal treatment, atmospheric
pressure is preferred simply for reasons of convenience.
The thermal treatment can be performed at a temperature of
up to about 925°C.
Prior to its use in the alkylation process of this
invention, the synthetic porous crystalline material should
be dehydrated, at least partially. This can be done by
heating the crystalline material to a temperature in the
range of from about 200°C to about 595°C in an atmosphere
such as air, nitrogen, etc., and at atmospheric,
subatmospheric or superatmospheric pressures for between
about 30 minutes to about 48 hours. Dehydration can also
be performed at room temperature merely by placing the
crystalline material in a vacuum, but a longer time is
required to obtain a sufficient amount of dehydration.
It may be desired to incorporate the synthetic porous
crystalline material for use herein with another material
' resistant to the temperatures and other conditions employed
in organic conversion processes. Such materials include
active and inactive materials and synthetic or naturally
occurring zeolites as well as inorganic materials such as
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clays, silica and/or metal oxides such as alumina. The
latter may be either naturally occurring or in the form of
gelatinous precipitates or gels including mixtures of
silica and metal oxides. Use of a material in conjunction
with the synthetic porous crystalline material, i.e.,
combined therewith or present during synthesis of the
crystalline material, which is active, tends to change the
conversion and/or selectivity of the catalyst in certain
organic conversion processes. Inactive materials suitably
serve as diluents to control the amount of conversion in a
given process so that products can be obtained economically
and orderly without employing other means for controlling
the rate of reaction. These materials may be incorporated
into naturally occurring clays, e.g., bentonite and kaolin,
to improve the crush strength of the catalyst under
commercial operating conditions. Said materials, i.e.,
clays, oxides, etc., function as binders for the catalyst.
It is desirable to provide a catalyst having good crush
strength because in commercial use it is desirable to
prevent the catalyst from breaking down into powder-like
materials. These clay and/or oxide binders have been
employed normally only for the purpose of improving the
crush strength of the catalyst.
Naturally occurring clays which can be composited with
the synthetic porous crystalline material include the
montmorillonite and kaolin family, which families include
the subbentonites, and the kaolins commonly known as Dixie,
McNamee, Georgia and Florida clays or others in which the
main mineral constituent is halloysite, kaolinite, dickite,
nacrite, or anauxite. Such clays can be used in the raw
state as originally mined or initially subjected to
calcination, acid treatment or chemical modification.
Binders useful for compositing with the present crystalline
material. also include inorganic oxides, notably alumina.
In addition to the foregoing materials, the
crystalline material can be composited with a porous matrix
material such as silica-alumina, silica-magnesia, silica-
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zirconia, silica-thoria, silica-beryllia, silica-titania as
well as ternary compositions such as silica-alumina-thoria,
silica-alumina-zirconia silica-alumina-magnesia and silica-
magnesia-zirconia.
The relative proportions of finely divided crystalline
material and inorganic oxide matrix vary widely, with the
crystal content ranging from about 1 to about 90 percent by
weight and more usually, particularly when the composite is
prepared in the form of beads, in the range of about 2 to
about 80 weight percent of the composite.
The stability of the catalyst for use herein may be
increased, by, for example, combining the as-synthesized
crystalline material with an alumina binder, converting the
alumina-bound material to the hydrogen form, and steaming
the alumina-bound material under conditions sufficient to
increase the stability of the catalyst. U.S. Patent Nos.
4,663,492; 4,594,146; 4,522,929; and, 4,429,176 describe
conditions for the steam stabilization of zeolite catalysts
which can be utilized to steam-stabilize the present
crystalline material. The steam stabilization conditions
include contacting the alumina- bound material with, e.g.,
5-1000 steam at a temperature of at least about 300°C
(e. g., 300-650°C) for at least one hour (e. g., 1-200 hours)
at a pressure of 101-2,500 kPa. In a more particular
embodiment, the alumina-bound crystalline material can be
made to undergo steaming with 75-100 steam at 315°-500°C
and atmospheric pressure for 2-25 hours. In accordance
with the steam stabilization treatment described in the
above-mentioned patents, steaming can take place under
conditions sufficient to initially increase the Alpha Value
of the catalyst, the significance of which is discussed
1~, and produce a steamed catalyst having a peak Alpha
Value. If desired, steaming can be continued to
' subsequently reduce the Alpha Value from the peak Alpha
Value to an Alpha Value which is substantially the same as
the Alpha Value of the unsteamed catalyst.
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The alkylation process of this invention is conducted
such that the organic reactants, i.e., the alkylatable
aromatic compound and the paraffin alkylating agent, are
brought into contact with the catalyst composition in a
suitable reaction zone such as, for example, in a flow
reactor containing a fixed bed of the catalyst composition,
under effective alkylation conditions. Such conditions
include a temperature of from about 0°C to about 500°C, a
pressure of from about 0.2 to about 250 atmospheres, a feed
weight hourly space velocity (WHSV) of from about 0.1 hr-1
to about 500 hr 1 and an alkylatable aromatic compound to
alkylating agent mole ratio of from about 0.1:1 to about
50:1. The WHSV is based upon the weight of the catalyst
composition employed, i.e., the total weight of active
catalyst (and binder if present). Preferred reaction
conditions include a temperature within the approximate
range of from about 100°C to about 450°C, a pressure of
from about 1 to about 25 atmospheres, a WHSV of from about
0.5 to about 100 hr-1 and an alkylatable aromatic compound
to alkylating agent mole ratio of from about 0.5:1 to about
5:1. The reactants can be in either the vapor phase or the
liquid phase and can be neat, i.e., free from intentional
admixture or dilution with other material, ar they can be
brought into contact with the zeolite catalyst composition
with the aid of carrier gases or diluents such as, for
example, hydrogen or nitrogen.
The alkylation process described herein can be carried
out as a batch-type, semi-continuous or continuous
operation utilizing a fixed or moving bed catalyst system.
A preferred embodiment entails use of a catalyst zone
wherein the hydrocarbon charge is passed concurrently or
countercurrently through a moving bed of particle-form
catalyst. The latter, after use, is conducted to a
regeneration zone where coke is burned from the catalyst in
an oxygen-containing atmosphere (such as air) at elevated
temperature, after which the regenerated catalyst is
_.. ... ~ , .
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recycled to the conversion zone for further contact with
the organic reactants.
As an embodiment of the present invention, benzene
levels in gasoline inventory are reduced by contacting the
gasoline stream with a C1-CS paraffin stream in, for
example, a 1:5 molar ratio over catalyst comprising MCM-22
at, for example, about 315°C, 500 psig, 1 hr-1 WHSV, and 0.5
HZ/paraffin molar ratio. The resultant alkylated product
will contain a lower benzene level due to ring alkylation
by the paraffin.
Another particularly useful embodiment of the present
invention results in improved light cycle oil (LCO)
quality. This is accomplished by contacting LCO with a C1-
C14 paraffin in, for example, a 1:5 molar ratio over
catalyst comprising MCM-22 at, for example, about 315°C,
500 psig, 1 hrl WHSV, and 2:1 H2/paraffin ratio.
Alklyation with C1-C6 paraffins will result in improved
distillate cetane values while reaction with the higher
molecular weight paraffins can produce a lubricant range
material, potentiallly removing the need for further
hydrotreating of the hydrocarbon stream.
In order to more fully illustrate the nature of the
invention and the manner of practicing same, the following
examples are presented.
To prepare a 65% MCM-22/35% alumina-bound catalyst for
use herein, a sample of as-synthesized MCM-22 was washed
with deionized water and dried at 120°C. A portion of the
resultant crystals was combined with A1203 to form a mixture
of 65 parts, by weight, MCM-22 and 35 parts alumina.
Sufficient water was added to this mixture to allow the
resulting catalyst to be formed into extrudates. The
catalyst.was calcined at 482°C in nitrogen followed by 6
hours in air at 538°C. The calcined extrudate was
exchanged with 1 N NHqN03 for 2 hours at room temperature.
The exchanged catalyst was washed with deionized water and
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the ammonium nitrate/water wash procedure repeated twice.
After drying at 120°C, the-catalyst particles were calcined
for 3 hours at 538°C in air.
F~X&MEhE 2
The catalyst of Example 1 was sized to 14/24 mesh, and
4 grams (8 cc) was loaded into a fixed-bed reactor. The
catalyst was dried by flowing 150 cc/minute of nitrogen for
3 hours at 260°C and 800 psig. Isobutane was then
introduced with an Isco pump at 56 grams/hour for 1 hour,
and then the flow rate was reduced to 4 grams/hour. 1-
Methylnaphthalene was then introduced at a rate of 4
grams/hour with a Milton Roy Mini-pump. Effective WHSV was
2 hr-1 overall. The temperature of the reactor was varied
from 367°C to 454°C and the pressure was maintained at 1000
psig. Both the liquid and gas products were evaluated with
a Hewlett-Packard gas chromatograph equipped with a DB-1
column. Liquid products were further characterized by gas
chromatography/mass spectrometry utilizing a Finnigan TSQ70
2o Triple Quadrupole Mass Spectometer equipped with a Varian
Gas Chromatograph with a DB-5 column. The results of the
experimental study of this example are shown in Table E.
The results are normalized to back out the isobutane in the
products.
These results show that under the experimental
conditions of this study we have been able to alkylate
methylnaphthalene with isobutane and also with lighter C1-C3
paraffin compounds which probably were formed from
isobutane cracking and subsequent naphthalene alkylation.
r , ,
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TABLE E
Temperature, C 367 399 427 454
Pressure, psig 1000 1000 1000 1000
%
t
t
d
~ ~
' S s, w 0. 00 0. 042 0. 134 0. 529
.
Co~onen
ze
No~a
Cl-Cz
C3 0.11 0.144 0.215 0.822
i-C9! 0.066 0.123 0.221 0.446
Other CQ 0.072 0.179 0.350 1.151
0 0.012 0.041 0.383
C8-Clo 0.127 0.455 0.343 0.323
Naphthalene 0.161 0.516 1.164 2.171
2-Methylnaphthalene 1.954 9.699 24.026 37.887
1-Methylnaphthalene 95.507 87.43 70.893 52.058
Cz Naphthalene 0.219 0.567 1.053 1.633
C3 Naphthalene 0.083 0.176 0.200 0.286
C9 Naphthalene 0 0.031 0.198 0.746
butyl-1-Me-Naphthalene 0.145 0.411 0.765 1.156
Unknown C11-Cls 0.557 0.200 0.383 0.391
C16+ 0 0.017 0.014 0.018
1-methyl-Naphthalene Conv. 2.238 11.445 28.181 47.270
Total methyl naphthalene
Conv. (1 & 2 based) 0.700 2.056 4.266 9.296
Isobutyl-Me-Naphthalene
Selectivity (1 & 2 based) 20.845 20.178 18.094 12.537
