Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
21 93951
~WO g~/Ol~i89 . ~ ,.S.
--1--
CATALYTIC SYSTEN FOR THE
REDUCTION OF NITROGEN OXIDES
.
This invention is concerned with the abatement of
nitrogen oxides and, optionally, other undesirable
compounds, in industrial and engine exhaust gases. In
particular, it is concerned with a catalytic method for
efficiently eliminating these undesirable " before
discharge to the a, ,h~re. It is more particularly
c~n~PrnPd with the use of a specially prepared catalyst
comprising an intermediate pore size zeolite that has been
treated or modified to contain iron or an iron ~- onnd for
the selective catalytic reduction of the NOX present in the
exhaust gas.
The present invention concerns a catalyst that is
useful for treating an exhaust gas comprising NOX and
ammonia, the catalyst comprising an int~ te pore size
zeolite and iron or an iron , _ ' that has been
hydrothermally treated, the hydrothermal treatment and the
iron concentration being effective to produce a catalyst
that is capable of converting at least 75 percent of the
NOy and ammonia present in the exhaust gas after the
catalyst has been treated in 100 percent steam at a
temperature of 700~C for 10 hours.
The present invention also concerns a process for
treating exhaust gas comprising NOX and ammonia comprising
contacting the exhaust gas with the catalyst described
above under conditions effective for the conversion of at
least a portion of the NOX and ammonia to innocuous
~ --
An embodiment of the invention is a method for
treating a gas mixture comprising NOX, ammonia, and,
optionally, at least one of CO and a hydrocarbon and
mixtures thereof, said method comprising directing the gas
mixture along with a source of oxygen, such as air, over a
catalyst under conditions effective for the selective
catalytic reduction of NOX, said catalyst comprising an
WO96/016~9 2 1 9 3 9 5 1 .~
int~ te pore size zeolite which has been treated to
contain iron or an iron _ulld, has been hydroth~rr~lly
treated at least once, and optionally further comprises a
binder.
As mentioned above, catalysts useful in this invention
comprise int~ te pore size zeolites that have been
treated or modified with iron or an iron ~- ~. The
iron may be added by ferrocene impregnation, ion-exchange
under specified conditions, contacting the zeolite with a
water soluble i~Uli containing salt or salt precursor,
contacting the zeolite with another type of inorganic iron-
containing ~ ', e.g., iron oxide, or the iron may be
incoL~ ted into the zeolite during the in-situ production
of the zeolite from zeolite seeds, silica, and ~lay. Each
of these methods will be further described below.
The term "exhaust gas" as used herein means any waste
gas which is formed in an industrial process or operation
and which is normally dicpo5~d of by discharge to the
~1 ~h~re, with or without additional treatment. "Exhaust
gas" also includes the gas produced by internal combustion
engines. The composition of such a gas varies and depends
on the particular process or operation which leads to its
formation.
The conversion of N0x to Nz is believed to proceed
Z5 generally according to equations (1) and (2).
2 N02+ 4 NH3 +~2 - > 3 N2+ 6 H20 (1)
4 N0 + 4 NH, +0z- > 4 N2~ 6 H20 (2)
This invention is effective for treating exhaust gas
containing the approximate stoichiometric amount of
ammonia. The ammonia may be present in the gas, may be
added to the gas, or may be produced by an upstream
process. As used herein, the expression "approximate
stoichiometric amount of ammonia" is intended to mean 0.75
to 1.25 times the molar amount of ammonia indicated in
equations tl) and (2) when excess oxygen is present.
Carbon monoxide and hydrocarbons present in the
exhaust gas may be oxidized to carbon dioxide and water
2 1 ~395 t
~ WO96~1~9 PCT~S9S/08253
--3--
over the catalyst. Additionally, hydrocarbons may be
selectively absorbed/~q~rhed on the catalyst.
Feeds
This invention is effective to treat industrial and
engine exhaust gases to remove N0x, and optionally other
undesirable c ~ ds~ such as C0 and hydrocarbons, if
present. These exhaust gases are typically produced in
internal combustion engines, and coal or gas-fired or oil-
fired furnaces, boilers and incinerators, and by the
manufacture of nitric acid, by the nitration of organic
~h~;C.~15, and by other chemical operations such as the
~e~,uc--~inq of spent nuclear fuel rods by dissolution in
nitric acid to recover uranyl nitrate followed by
calcination to convert the nitrate to uranium oxide.
Process Conditions
The exhaust gas may be treated in the catalytic system
of this invention at a temperature of 200 C to l,OOO-C or
more, e.g., within the range of 225~C to 900-C, e.g., of
225~C to 750~C, e.g., of 250-C to 600~C and at a gas hourly
space velocity, GHS~, (vols. of gas at STP per volume of
catalyst per hour) adjusted to provide the desired
conversion. The GHSV can be from 1,000 to 500,000 hr~l,
e.g., within the range of 2,500 to 250,000 hr~~, e.g., from
5,000 to 150,000 hr~l, e.g., from 10,000 to 100,000 hr~l.
The process of this invention may be operated at
subd ~-ric to superatmospheric pressure, e.g. at 34.5
to 3,450 kPaa (5 to 500 psia), e.g., at 68.9 to 345 kPaa
(10 to 50 psia), i.e. near or slightly abo~e ai ~ ric
pressure.
The gas mixture directed over the catalyst m~y contain
at least a stoichiometric amount of oxygen as indicated by
eguations (1) and (2) above. Excess levels of oxygen above
the stoichiometric amount may be desirable. In the method
of this invention, a source of oxygen, such as air, is co-
fed over the catalyst along with the exhaust gas. If
2 1 93q5 1
WO'~6/01689
--4--
sufficient oxygen is not present in the exhaust gas, a
source of oxygen, e.g. air, may be added to the exhaust
gas, and if sufficient oxygen i5 present in the exhaust
gas, no air need be added to the exhaust gas.
Adequate conversion may be readily achieved with a
simple stationary fixed-bed of catalyst. However, other
contacting means are also contemplated, such as contacting
with a fluid bed, a transport bed, and a monolithic
catalyst structure such as a honeycomb. Suitable mixing
may be used in the exhaust gas before the treatment
according to the present invention to produce a homogeneous
gas mixture for treatment.
Catalvst r~nn~itiOn
Catalysts useful in this invention may comprise an
active material and a support or binder. The support for
the catalysts of this invention may be the samc as the
active material and further can be a synthetic or naturally
occurring substance as well as an inorganic material such
as clay, silica, zirconia, titania and~or one or more other
metal oxides. One binder that is suitable is d low acidity
titania prepared from a mixture comprising a low acidity
titanium oxide binder material and an aqueous slurry of
titanium oxide hydrate. The preferred support is one that
is a high surface area material that also possesses a high
temperature stability and further possesses a high
oxidation stability.
The binder may be prepared according to methods
disclosed in U.S. Patent Nos. 5,430,000; 4,631,267;
4,631,268; 4,637,995; and 4,657,880. Also, the catalysts
described herein may be combined with any of the binder
precursors described in the above application and patents,
and then may be formed, such as by extrusion, into the
shape desired, and then hydrothermally treated and/or
calcined as hereinafter described. The preferred binder
may include less than 50 weight percent alumina, e.g., less
than 2 weight percent alumina, e.g., is substantially free
= =
21 93951
~ WO ~IG89 -~ P~
--5--
of alumina. By the term "substantially free of alumina" is
meant that no alumina is intentionally added to the binder,
however, it is recognized that trace amounts of alumina may
be present.
When low acidity titania is used as a binder, it may
be desirable that the formable, e.g., extrudable, mass
prepared by combininy the zeolite, the iron salt, and the
titania binder precursors contain at least 0.5 wt.%, e.g.,
1 wt.% to 20 wt.%, e.g., 2 to 8 wt.~ of the aqueous slurry
of titanium oxide hydrate.
The low acidity titania may be added in dry
particulate form, e.g., titanium oxide hydrate, so as to
control the moisture content of the binder/dispersant
mixture at a level to promote satisfactory forming, e.g.,
lS extrusion.
The catalysts may also contain stabilizers such as
~lk~l in~ earth oxides, phosphates and combinations thereof.
Catalysts useful in invention are frequently used with
a substrate. A material can be both substrate and part of
the catalyst. The catalyst may be combined with the
substrate in any method that ensures that the catalyst will
remain intact during the catalytic reaction, e,g., the
c~talyst may be present as a coating on the substrate, or
it can be present as an integral part of the substrate.
The catalyst useful in this invention will now be
described in detail. It comprises an intermediate pore
size zeolite (e.g., less than 7 Angstroms pore size, such
as from 5 to less than 7 Angstroms) having a silica to
alumina molar ratio of at least 5, e.g., at least 20, e.g.,
between 40 and 1000, e.g., 50 to 500, a Constraint Index of
1 to 12, said zeolite having been treated or modified to
contain iron or a iron compound. The Constraint Index
qualifies it as having an intermediate pore size. The
method by which Constraint Index is det~min~d is described
fully in U.S. Pat. No. 4,016,218.
Examples of such zeolites include ZSM-5 (U.S. Patent
No. 3,702,886 and Re. 29,948); ZSM-ll (U.S. Patent No.
WO96~16~ ~ 2 1 q 3 ~ 5 ~ r~
-6-
3,709,979); 28M-12 (U.S. Patent No. 3,8~2,449~; ZSM-21
~U.S. Patent No. 4,046,859); ZSM-22 (U.S. Patent No.
4,556,477); Z~3N-23 (U.S. Patent No. 4,076,842~; ZSM-35
(U.S. Patent No. 4,016,245); ZSM-38 (U.S. Patent No.
4,406,859~; gSM-48 (U.S. Patent No. 4,397,827); ZSM-57
(U.S. Patent No. 4,046,685); and ZSM-58 (U.S. Patent No.
4,417,780).
A catalyst useful in the method of this invention may
be prepared by combining a zeolite, such as ~ZSM-5, an iron
salt or other iron containing _ ~, a high molecular
weight, hydroxy functional silicone, such as Dow Corning
~6-2230 silicone resin, a suitable extrusion aid, such as
methyl cellulose, and a suitable polar, water soluble
carrier, such as methanol, ethanol, isopropyl alcohol, N-
methyl pyrrolidone or a dibasic ester along with water asneeded, then forming the mixture into the desired shape,
such as by extrusion, then simultaneously calcining and
hydrothermally treating the formed material. One
particular methyl cellulose that is effective as an
extrusion aid in the method of this invention i8 a
hydroxypropyl methyl cellulose, such as K75M Methocel~,
available from Dow Ch~mic~l CO. Dibasic esters that are
useful in this invention include dimethyl glutarate,
dimethyl succinate, dimethyl adipate, and mixtures thereof,
one example of which is DuPont Chemical Co. DBE, which
typically comprises 50 to 75 percent dimethyl glutarate, 10
to 25 percent dimethyl adipate, 19 to 26 percent dimethyl
succinate and less than 0.2 wt.% methanol. Other silicone
resins that may be used in the method of this invention
include those described in U.S. Patent No. 3,090,691.
The relative proportions of zeolite component and the
support material on an anhydrous basis may vary widely with
the zeolite content ranging from between 5 to 99 percent by
weight and more usually in the range of 10 to 95 percent by
weight, specifically from 20 to 9o percent by weight of the
dry composite.
2 1 9395 ~
~ WO96~1689 r~
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Original ions, e.g., alkali or alkaline earth metal,
of the as-synthesized intermediate pore size material and
any found in the zeolite/support material can be replaced
in accordance with terhniq~C well known in the art, at
least in part, by ion-exchanye with other ions. For the
present catalyst composition, preferred replacing ions
include hydL~g~n ions and hydL~gell precursor, e.g.,
; ;nn ions. ZSM-5 in the hydrogen exchanged form is
referred to herein as HZSM-5. Representative ion-exchange
techniques are disclosed in a wide variety of patents
including U.S. Patents 3,140,249: 3,140,251; and
3,140,253.
The desired iron loadiny on the zeolite -nent of
the catalyst is O.Ol to 5 wt.%, e.g., at least 0.4 wt.~,
e.g., at least 0.6 wt.%, e.g., at least 1 wt.%, e.g., at
least 1.5 wt.~, preferably 2 wt.%, iron into the zeolite.
The catalyst may also optionally include another metal,
such as a transition metal, preferably a noble metal, the
combination of the metals being able to oxidize other
undesirable -c present in the exhaust gas along with
allowing the SCR of NOX. The metal may be at least one of
copper, zinc, vanadium, chroïnium, r-nq~n~ce, cobalt,
nickel, palladium, platinum, molybdenum, tungsten, sodium,
potassium, magnesium, calcium, barium, cerium and mixtures
thereof, with the noble metals, platinum, palladium and
combinations of these, along with cerium, particularly
preferred. The terms "metal" and "iron" as used herein are
intended to include the elemental metal as well as metal
oxides, metal sulfides, and other metal containing
compounds.
After the int~ te pore size zeolites have been
treated or modified to contain iron or an iron compound,
they may be washed with water and dried at a temperature
ranging from 65 C to 315~C. They may also be calcined or
thermally treated in air, or in an inert gas, at
temperatures ranging from 260~C to 925 C for periods of
time ranging from 1 to 48 hours or more, typically at 538~C
2 ~ 939~ 1
WO 96/lll6X9 rc
-8-
for 4 to 6 hours. ~hile suba ---phlric or superatmospheric
can be employed for the thermal treatment,
~ Aric p~es~uL~ is preferred simply for reasons of
convenience.
Catalysts of i L~ved selectivity and other beneficial
properties, such as improved resistance to ageing in an
atmosphere containing steam, can be obtained by subjecting
the iron containing zeolite to at least one treatment with
strea~s containing steam (hydrothermally treating the
catalysts) at elevated temperatures ranging from 260-C to
goo-C, e.g., 400~C to 850-C, e.g., 500~C to 750 c. The
hydrothermal treatment may be accomplished in an atmosphere
containing at least 20 ppm, 0.5%, 5, 10~, 20%, even up to
99% steam in air or some other suitable gas stream or in an
ai - ~'~re consisting of steam or nitrogen and some other
gas which is essentially inert to the zeolite. Optionally,
more than one hydrothermal treatment may be used,
specifically two, three, or more hydrothermal treatments at
different temperatures, e.g., increasing temperatures, may
be used. Examples of steaming conditions include 600 C
with 10 percent steam in air for 10 hours, 700 to 750-C
with 5 to 10 percent steam in air for 6 to 10 hours, and
850-C with 20 percent steam in air for 6 hours. Typical
steaming conditions are described in U.S. Patent Nos.
4,429,176; 4,522,929; 4,594,146; and 4,6~3,492. The
calcination and hydroth~r-l treatments of the catalysts
are preferably combined into one treatment step and
-conducted simultaneously.
As mentioned above, the iron may be added to the
catalyst by ferrocene impregnation, ion-exchange under
specified conditions, contacting the zeolite with an
inorganic iron-containing salt or salt precursor,
contacting the zeolite with another type of inorganic iron-
containing compound, e.g., iron powder or iron oxide, or
the iron may be incorporated into the zeolite during the
in-situ production of the zeolite from zeolite seeds,
silica, and clay.
2 1 9395 1~ WO9~0lC89 r~
_9_
Ferrocene impregnated catalysts may be prepared by
contacting the zeolite with ferrocene which has been
dissolved in a suitable solvent. Suitable solvents are
those which dissolve the ferrocene and may then be removed
from the impregnated zeolite under conditions sufficiently
mild as to avoid causing the ferrocene to sublimate off the
zeolite. Examples of suitable organic solvents include
benzene, toluene, xylenes, and hexane among others. The
impregnation is typically conducted for more than 4 hours,
specifically from 4 hours to several days, more
specifically from 6 hours to 100 hours. The impregnation
is generally conducted at conditions cffective to achieve
the desired iron loading or iron concentration on the
zeolite.
The impregnation may occur either before or after the
zeolite is combined with the support. For example, if the
zeolite is first combined with the support and then
impregnated, ferrocene that is deposited on the surface of
the zeolite and on the support may be washed off using a
solvent having an effective atomic diameter that is larger
than the zeolite pore size, e.g., an organic solvent such
as Tetralin~.
The impregnation may be conducted after first drying
or dehydrating the zeolite. Also, the ferrocene solution
may be preparcd using a water-free or dry solvent.
The impregnated zeolite is recovered by removing the
solvent from the zeolite. It is desired to remove the
solvent without causing the rerrocene to sublimate off the
zeolite. One possible way i5 to evaporate the solvent at a
temperature less than the ferrocene sublimation
temperature, 100-C. This solvent removal may be done at
superai _~h~ric pressure, if desired, or pressures ranging
from sub~ ric to atmospheric. The recovered
ferrocene impregnated zeolite then may be calcined at 450-C
to 550~C to oxidize the ferrocene and to convert the iron
to its oxide.
21 ~3951
WO g6,0~68~ . ~ I .
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Another catalyst comprises an inti ~';~te pore size
zeolite which has been exposed to at leas~ one ion-exchange
sequence under specific conditions, wherein the ion-
exchange sequence comprises the steps of contacting the
in~r~ te pore size zeolite with an aqueous solution of
a ferrous, Fe(II), salt under suitable conditions,
recovering the zeolite, and calcining the zeolite. The
conditions include those effective to ~uba~dl,Lially prevent
oxidation of the ferrous ion to the ferric form, such as
using nitrogen, argon and the like inert gases to blanket
the solution. The conditions also include stirring or
mixing at a temperature of above 55-C, specifically above
65-C, or those temperatures effective to reduce the
hydration sphere of the ferrous cation to a size small
enough to enter the pores of the zeolite. The ferrous
cation is reported to have an ionic radius in an aqueous
solution of about 0.0000000006 meters (6 A) at 25'C, which
is too large to enter ~SM-5 pores, which are slightly
smaller than this. Increasing temperature is believed to
reduce the size of the hydration sphere associated with the
ferrous cation. For example, with increasing temperature,
a ferrous ~ _ ', ferrous sulfate, changes from the
heptahydrate form to the tetrahydrate form (at 56.6 C) and
then to the monohydrate form (at 65-C~.
The ion-exchange may be conducted for more than 4
hours, e.g., from 4 hours to several days, e.g., from 6
hours to 100 hours. During the ion-exchange, the pH of the
aqueous solution may be maintained between 1 and 4.~ or at
a pH level effective to prevent precipitation of the
ferrous salt.
It has been found that ferrous, Fe(II~, ions are more
readily exchanged into the zeolite than ferric, Fe(III),
ions.
Ferrous, ~e(II), salts useful in this invention
include the water soluble salts, such as, ferrous ~mm~n;um
sulfate, ferrous chloride, ferrous fluosilicate, ferrous
hyposulfite, ferrous iodide, ferrous lactate, ferrous
21 93951
~WO96101689 -ll- r~
nitrate, ferrous perchlorate, ferrous sulfate, and ferrous
thiocyanate.
After the iron has been ion-oYrh~nqed into the
zeolite, the zeolite may be recovered by cooling the
aqueous solution below 55~C to 65-C, filtering the zeolite
from the aqueous solution and washing the filtered zeolite
with a neutral or slightly basic solvent, for example, an
aqueous solvent with a pH of from 6 to 9, such as distilled
or deionized water. The solvent washing may be conducted
at conditions effective to avoid leaching the iron from the
zeolite. The aqueous solution and the ion-exchanged
zeolite need not be maintained under inert conditions after
the solution has been cooled. The I~cuv~ed zeolite may be
dried, calcined and hydrothermally treated as more fully
described herein.
The ion-exchange sequence described above may be
conducted at least once, e.g., at least twice, e.g., at
least three times, e.g., four or more times.
Another method to incorporate iron onto the zeolite is
to contact an into ~ te pore size zeolite with an iron
salt or salt precursor. In this method, the iron salt may
first be dissolved in water or another suitable solvent and
then the zeolite may be contacted with the solution.
Alternatively, the iron salt and the zeolite, and any
binder material desired, may be physically combined and
then water or another suitable solvent added and the
mixture recovered and formed, as desired. The formed
material may be dried, calcined, or hydrothermally treated
as is more fully described herein. A~ will be apparent to
one skilled in the art, any method that is effective to
contact the zeolite with the iron salt and to achieve a
high degree of iron distribution on and inside the zeolite
may be used, including, but not limited to an incipient
wetness torhnique~
Suitable iron salts include all of the ferrous salts
mentioned above, as well as ferric acetate, iron(III)
benzoate, iron(III) cacodylate, iron(III) dichromate,
WOs6~ 2 1 9 3 9 5 1 ~
-12-
iron(III) citrate, iron~III) fluoride, iron(III)
fluosilicate, iron(III) formate, iron(III)
glycelvL,~ h~te, iron(III) llydsogel, cyanide, iron(IlI)
hydrosulfate, iron(III~ lactate, iron(III) malate,
iron(III) oxalate, iron(III) orth~ te~ iron(III)
hypophosphite~ iron(III) sulfide, iron(III) thiocyanate,
ferric acetylacetonate, ferric ammoniumchloride, ferric
chloride, iron(III) nitrate nanohydrate, iron~III) sulfate
pentahydrate, i inm ferric sulfate, ferric bromide,
ferric iodide, and any other ferrous, ferric, or other iron
salts that are water soluble. Also included are precursors
of all of the salts mentioned above.
The incorporation of iron onto the zeolite may be
accomplished by contacting an intermediate pore size
zeolite with an iron salt or salt precursor, such as those
mentioned above. In this method, the iron salt may first
be dissolved in water or another suitable carrier or
solvent and then the zeolite may be contacted with the
solution, recovered from the solution, dried and then bound
20 if desired. Alternatively, the iron salt and the zeolite,
and any binder material desired, may be physically combined
with water or another suitable carrier or solvent to
produce a mixture and the mixture recovered and formed,
such as by extrusion. The formed material may be dried,
calcined, or hydrothermally treated as is more fully
described herein. As will be apparent to one skilled in
the art, any method that is effective to contact the
zeolite with the iron salt may be used, including, but not
limited to mulling or an incipient wetness techni~ue.
Yet another method that is suitable to add iron to the
zeolite is to physically contact an intermediate pore size
zeolite with an inorganic iron-containing compound, e.g.,
iron oxide. In this method, it is preferred to use a
finely divided iron-containing compound, such as a fine
pigment grade red iron oxide. It is also preferred to add
a binder pLe~UL~VS to the physical mixture of the iron-
containing compound and the zeolite and to form the
2 1 9395 1
~ W096/016~ -13- P~~
physical mixture. After the desired shape has been formed,
the i~on contacted zeolite may be calcined and
hydrothermally treated as is more fully described herein.
Another catalyst may be prepared by in-situ
crystallization of an ay~L~te~ e.g., a preformed clay
E~.~Ley~te. The ay~L~te comprises four ~ A~ts: seeds
of an int~ te pore size zeolite, e.g., ZSM-5 seeds,
silica, e.g., a colloidal silica such as Ludox~ available
from E. I. DuPont de Nemours & Co., clay, and iron oxide.
optionally, the aggregate can also include alumina.
Various terhni~lAc for preparing an in-situ crystallized
zeolite are described in U.S. Patent Nos. 4,522,705;
4,091,007; and 4,800,187.
The zeolite may be prepared from a clay aggregate
which comprises a non-clay added source of silica. The
sources of silica in the reaction mixture may include both
a clay and a non-clay source of silica, or a clay alone.
Non-clay sources of silica that can be employed in the
synthesis are Ludox~, an aqueous dispersion of colloidal
silica, water glass, sand, silica gel, fused silica, and
finely-divided precipitated silicas, such as Hi-Sil, Quso,
and Zeosil 100.
The clay cn~pon-Ant which is treated to form the
zeolite-containing catalyst can be selected from the group
consisting of kaolin, halloysite, montmorillonite, illite,
and dickite, with kaolin preferred.
The preformed aggregate may be treated for one or more
hours at a temperature sufficient to convert the clay into
the me~k~nl in phase, e.g., greater than 927~C to 1000~C.
After the thermal treatment of the aggregate, the zeolite
may be crystallized by treatment at a temperature of
greater than 135'C, e.g., 149~C, in the presence of water,
alkali metal cations, and optionally, a directing agent
such as tetraalkylammonium ions, e.g., a tetraalkylammonium
halide, such as tetrapropylammonium bromide, or a n-
alkylamine, such as n-propylamine, with no additional
nutrients for zeolite formation.
WO~0168~ 2 l 9 3 9 5 1 r~
-14-
The in-situ formed zeolite may be prepared from a
aggregate comprising about 3-5% zeolite seeds, e.g., ZSM-5
seeds; 23-25~ silica, e.g. colloidal silica; 68-70% clay,
e.g., kaolin clay; and 0.01-5$ metal oxide, e.g., iron
oxide.
As noted above, the catalytic reduction of nitrogen
oxides is substantially effected by the use of the present
process. By substantially effected is meant a conversion
of greater than 40, 75, 80, 85, 90, 95, or even 99% or more
of the nitrogen oxides and the ammonia in the exhaust gas
to innocuous ~ _ -c, such as nitrogen, through the use
of this process. This is also referred to herein as
conversion of a substantial portion of the N0x and ammonia
in the exhaust gas to innocuouq compounds.
Exam~le 1
Base ZSM-5
A HZS~-5 sample, prepared according to U.S. Patent No.
3,702,886, was used as the reference sample and was used as
the basis for all of the other examples.
Exam~le 2
Preparation of an iron containing ZSM-5
An iron containing ZSM-5 sample was prepared by the
following method: lO0 g of distilled water was heated to
about 85-C with constant stirring under a blanket of dry
nitrogen. Approximately 0.11 g of ferrous sulfate and 5.1
g o~ the same HZSM-5 as Example l were added to the heated
water. A solution p~ of about 2 was maintained by dropwise
addition of nitric acid or ammonium hydroxide, as needed.
The exchange solution was maintained at about 85-C under a
nitrogen blanket with continued stirring for approximately
17 hours. The solution was subsequently cooled to room
temperature, filtered and washed with distilled water. The
filtered solid was calcined in air for 8 hours at 538 C to
produce the iron containing catalyst, Catalyst A. The iron
loading of this catalyst as prepared is about 0.5 wt.~.
~ WO96~1689 2 1 9 3 9 5 ~
-15-
Example 3
Comparative testing against the base ZSM-5
In this example, the SCR activity of Catalyst A is
compared with the base HZSM-5 catalyst from Example l. The
catalyst samples were evaluated using a fixed bed quartz
reactor operating between 250-550-C. The reactor inlet
contained 500 ppm N0, 500 ppm NH" and 5 vol.% ~2 in a He
carrier flowing at a constant gas hourly space velocity
(GHSV) of 12,000 hr~1. The effluent from the reactor was
cont;nuouCly monitored by non-dispersive infrared
spectroscopy (NDIR) detectors. Catalyst activity results
are reported below in Table l.
Table l
Percent N in Feed Converted to N~
Tem~erature. ~C Base ZS~-5 Catalvst Catalvst A
550 89% 93%
455 100% 98%
400 lO0~ 98~
345 71~ 97%
250 26~ 92
Exam~le 4
Preparation of an Iron Containing ZSM-5
An iron containing ZSM-5 sample was prepared by the
following method: a solution containing 25 g of the same
HZSM-5 as Example l and 500 g of distilled water was heated
to about 77 C with constant stirring under a blanket of dry
argon. Approximately 0.3 g of ammonium ferrous sulfate was
added to the heated solution. A solution pH of 3 was
maintained by dropwise addition of nitric acid or ammonium
hydroxide, as needed. The exchange solution was maintained
at about 77 C under an argon blanket with continuous
stirring for approximately 9 hours. The solution was
subsequently cooled to room tcmperature, filtered and
21 93q51
W096101689
-16-
washed with distilled water. The filtered solid was
calcined in air $or 8 hours at 538 C to produce the iron
c~nt~ining catalyst, Catalyst B. Ihe iron loading of this
catalyst as prepared is about 0.5 wt.%.
ExamPle 5
Comparative testing against a base ZSM-5
In this example, the SCR activity of Catalyst B is
compared with the base HZSM-5 catalyst from Example l. The
catalyst samples were evaluated using similar equipment and
the same procedure as Example 3. Catalyst activity results
are reported below in Table 2.
Table 2
Percent N in Feed Converted to N2
I~ _L~uLe. 'Ç Base ZSM-5 Çatalvst Çatalvst B
15 550 8g% 100%
455 100% 100%
400 '100% 100%
345 71% 100%
250 26% 90%
Exam~le 6
Preparation of an Iron Containing ZSM-5
An iron containing ZSM-5 sample was prepared by the
following method: a solution containing 0.2354 g of
ferrous acetate in 30 g distilled water was added to a
flask containing 15 g of the same HZSM-5 as Example l at
room te1.y~L~LuL~. The catalyst slurry was mixed for
approxi~ately 2 hours and was air dried at room temperature
for about 16 hours. The dried catalyst was calcined in air
~or 8 hours at 538-C to produce the iron containing
catalyst, Catalyst C. The iron loading of this catalyst as
prepared is about 0.5 wt.%.
2 1 ~3~5 1
~ WO96/01689 ~ .iA
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ExamPle 7
Comparative testing against a base ZSM-5 and Catalyst A
In this example, the SCR activity of Catalyst C is
compared with the base HZSM-5 catalyst from Example 1 and
Catalyst A as prepared in Example 2. The catalyst samples
were evaluated using similar equipment and the same
pLOCedu~e as Example 3. Catalyst activity results are
reported below in Table 3.
Table 3
Percent N in Feed Converted to N2
TemPerature,~C Base Catalvst CatalYst A Catalvst C
550 89% 93% 89%
455 100% 98% 91%
400 100% 98% 91%
345 71% 97% 90%
250 26% 92% 85%
ExamPle 8
Preparation of an iron containing HZSM-5
An iron containing ZSM-5 catalyst was prepared by the
following method: 7.6 g of the same HZSM-5 as that of
Example 1 was heated in a stream of dry nitrogen to 375 C.
After this temperature was maintained for 4 hours, the
catalyst was cooled, in a stream of dry nitrogen, to room
temperature. A solution of 0.5 g of ferrocene
(dicyclopentadienyliron) in 30 g dry benzene was then added
to the calcined zeolite and the slurry allowed to mix on a
roller for about 16 hours. The benzene was allowed to
evaporate at room temperature to give a benzene/ferrocene
wetted zeolite. This wet solid was then heated to a
temperature that did not exceed lOO-C in a vacuum oven so
as to remove the residual benzene. This dry catalyst was
then calcined in a stream of air at about 450-C for about 6
Wo96~16~ 2 1 9 3 q 5 1 . ~
-18-
hours to produce the desired iron containing catalyst,
Catalyst D. The iron loading of this catalyst is about 1.8
wt.~.
Exam~le 9
Catalytic evaluation of Catalyst D
In this example, the SCR activity of Catalyst D from
Example 8 was evaluated. The catalyst sample was evaluated
using similar equipment and the same procedure as Example
3. Catalyst activity results are reported below in
Table 4.
Tab~e 4
Percent N in Feed Converted to N~
T~nerature. ~C Catalvst D
550 9o~
455 97
400 98~
345 98%
250 95%
Exam~le lo
Preparation of an iron containing HZSM-5
An iron containing ZSM-5 catalyst was prepared by the
following method: about lO g of the same H2SM-5 as that of
Example 1 was heated in a stream o~ dry air to 375~C for 4
hours and then was cooled to room temperature. A solution
of 0.1667 g of ferrocene (dicyclopentadienyliron) in 30 g
dry toluene was then added to the dried zeolite and the
slurry was mixed at room temperature overnight. Excess
toluene was allowed to evaporate at room temperature to
give a toluene/ferrocene wetted zeolite. The recovered
solid was then calcined in a stream of dry air at about
538-C for about 6 hours to produce the desired iron
containing catalyst, Catalyst E. The iron loading of this
catalyst is about 0.45 wt.~.
21 93951
~wo s6ml6ss -19- r~
ExamPle 11
Catalytic evaluation of Catalyst E
In this example, the SCR activity of Catalyst E from
Example 10 was evaluated using similar ~li --L and the
same procedure as Example 3. Catalyst activity results are
reported below in Table 5.
Tab~e 5
Percent N in Feed Converted to N2
Tem~erature. ~C CatalYst E
550 98
455 99%
400 99%
345 98%
250 81%
Exam~le 12
Preparation of an iron containing HZSM-5
An iron containing ZSM-5 catalyst was prepared by the
following method: about 10 g of the same HZSM-5 as that of
Example 1 was heated in a stream of dry air to 375~C for 4
hours and then was cooled to room temperature. A solution
of 0.3331 g of ferrocene tdicyclopentadienyliron) in 30 g
dry toluene was then added to the dried zeolite and the
slurry was mixed at room temperature overnight. The slurry
was filtered and washed once with 100 ml of Tetralin~ to
remove excess ferrocene from the external surface of the
zeolite. Excess Tetralin~ was, allowed to evaporate at room
temperature to give a TetralinX/ferrocene wetted zeolite.
The recovered solid was then calcined in a stream of dry
air at about 538'C for about 6 hours to produce the desired
iron containing catalyst, Catalyst F. The iron loading of
this catalyst is about 0.66 wt.%.
wo g6,0l689 2 1 9 3 9 5 1 P ~u~
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Exam~le 13
Catalytic evaluation of Catalyst F
In this example, the SCR activity of Catalyst F from
Example 12 was evaluated using similar e~ and the
same ploceduLe as Example 3. Catalyst activity results are
reported below in Table 6.
Table 6
Percent N in Feed Converted to N2
Tem~erature. ~C CatalYst F
550 96
455 98~
400 98%
345 96%
250 88%
Exam~le 14
Preparation of an iron containing HZSM-5
An iron containing ZSM-5 catalyst was prepared by the
following method: about 10 g of the same HZSN-5 as that of
Example 1 was heated in a stream of dry air to 3~5-C for 4
hours and then was cooled to room temperature. A solution
of 0.3331 g of ferrocene (dicyclopentadienyliron) in 30 g
dry toluene was then added to the dried zeolite and the
slurry was mixed at room temperature overnight. Excess
toluene was allowed to evaporate at room temperature to
give a toluene~ferrocene wetted zeolite. The recovered
solid was then calcined in a stream of dry air at about
538-C for about 6 hours to produce the desired iron
containing catalyst, Catalyst G. The iron loading of this
catalyst is about 1.05 wt.%.
2 1 9395 1
~ WO96~1689
-21-
Example 15
Catalytic evaluation of Catalyst G
In this example, the SCR activity of Catalyst G from
Example 14 was evaluated using similar e~uipment and the
same pLuCed~L- as Example 3. Catalyst activity results are
reported below in Table 7.
Table 7
Percent N in Feed Converted to N2
Temperature. ~C CatalYst G
550 95%
455 98%
400 98%
345 97%
250 91%
Exam~le 16
Aging of the HZSM-5 catalysts
The base HZSM-5 of Example 1 and Catalysts D through G
as prepared above in Examples 8, 10, 12, and 14 were
hydrothcrmally aged. Approximately 5 g of each catalyst
was placed in individual identical crucibles and put in a
controlled al ~ re furnace. The furnace was
continuously purged with air containing 20 wt.% water
vapor. The samples were treated in this moist atmosphere
at 850~C for 6 hours. The treated samples will be referred
to as aged base HZSM-5, and aged Catalysts D through G.
Exam~le 17
Catalytic evaluation of aged base HZSM-5
In this example, the SCR activity of the aged base
HZSM-5 from Example 16 was evaluated using similar
~cll; nt and the same procedure as Example 3. Catalyst
activity results are reported below in Table 8.
21 93951
W0~6~1689 r~u~
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Table 8
Percent N in Feed Converted to N2
I~ ~Lur~. ~C A~ed base HZSM-5
550 82
4S5 56
400 36
345 20
250 9
Exam~le 18
Catalytic evaluation of aged Catalyst D
In this example, the SCR activity o~ the aged Catalyst
D from Example 16 was evaluated using similar equipment and
the same ~ ed~e as Example 3. Catalyst activity results
are reported below in Table 9.
Table 9
Percent N in Feed Converted to ~2
Te~era~e. ~C Aqed Catalvst D
550 g8%
455 100%
400 100%
345 98
250 96
Exam~le 19
Catalytic evaluation of aged Catalyst E
In this example, the SCR activity o~ the aged Catalyst
E from Example 16 was evaluated using si~ilar ~ and
the same procedure as Example 3. Catalyst activity results
are reported below in Table 10.
_ _ _ _ _ _ _ _ .. . . . _ . . _ ...
2 1 93951
~ W096l0l68~ -23- I~
Tahle 10
Percent N in Feed Converted to N2
Tem~erature, ~C Aaed Catalvst E
550 98%
455 100~
400 99%
345 88~
250 37%
ExamPle 20
Catalytic evaluation of aqed Catalyst F
In this example, the SCR activity of the aged Catalyst
F from Example 16 was evaluated using similar equipment and
the same procedure as Example 3. Catalyst activity results
are reported below in Table 11.
Table 11
Percent N in Feed Converted to N2
TP~n~rature. ~C A~ed CatalYst F
550 9g%
455 99%
400 92%
345 57%
250 27%
Exam~le 21
Catalytic evaluation of aged Catalyst G
In this example, the SC~ activity of the aged Catalyst
G from Example 16 was evaluated using similar equipment and
the same procedure as Examplc 3. Catalyst activity results
are reported below in Table 12.
WO 9~11689 2 1 9 3 9 5 1 "~ J, ~
- 24 -
Table 12
Percent N in Feed Converted to N2
Te~nerature. 'C A~ed Catalvst G
550 97%
455 100~
400 99%
345 90
250 33
ExamPle 22
Preparation of an iron containing ZSM-5
An iron containing ZSM-5 catalyst was prepared by the
following method: about 20 g of illm iron(III~ sulfate
was dissolved in 74 g distilled water. This solution was
added to about 120 g of the base HZSM-5 and the slurry was
15 mixed at about room temperature and was then dried at about
lOO-C overnight. Approximately 10 g of the dri.ed,
impregnated solid was then calcined in air at about 600 C
with about 10% steam for about 10 hours to produce the
desired iron containing catalyst, Catalyst ~. The iron
loading of this catalyst is about 2 wt.~.
ExamPle 23
Catalytic evaluation of Catalyst H
In this example, the SCR activity of Catalyst H from
Example 22 was evaluated using similar equipment and the
25 same procedure as Example 3. Catalyst activity results are
reported below in Table 13.
21 93951
~ WOg610168g IR,~ el
-25-
Table 13
Percent N in Feed Converted to N,
T~nerat~re. ~C Catalvst H
550 76%
455 95
400 99%
345 98
250 90
Exam~le 24
Preparation of an iron containing ZSM-5
An iron containing ZSM-5 catalyst was prepared by the
following method: about 1.5 g of iron~III) nitrate was
dissolved in 6.5 g distilled water. This solution was
added to about 10 g of the base HZSM-.S and the slurry was
mixed at about room temperature and was then dried at about
lOO-C overnight. The dried, impregnated solid was then
calcined in air at about 600~C with about 10~ steam for
about 10 hours to produce the desired iron containing
catalyst, Catalyst I. The i3'0n loading of this catalyst is
about 2 wt.~.
ExamPle 25
Catalytic evaluation of Catalyst I
In this example, the SCR activity of Catalyst I from
Example 24 was evaluated using similar equipment and the
same procedure as Example 3. Catalyst activity results are
reported below in Table 14.
21 93951
WO96/01~89 l~1
-26-
Table l~
Percent N in Feed Converted to N
TeDDerature. 'C Catalvst I
550 86%
455 97%
400 99%
345 99
250 92%
Exam~le 26
Preparation of a silica bound-iron containing ~SM-5
A silica bound iron containing ~SM-5 catalyst was
prepared by the following method: about lO0 g of the
dried, iron impregnated HZSM-5 catalyst prepared in Example
22 was dry blended with about 22 g of Dow Corning siliconc
resin (Q6-2230~ and about 6.8 g of X75M Methocel~
(available from Dow Ch~mic~l Co.~. Approximately 89 ml of
a l:l by volume mixture of water:isopropyl alcohol was then
added to the dry blended powder. The slurry was mulled for
a minimum of 5 minutes until the mixture reached the proper
consistency for extrusion. The mixture was then extruded
into l/16 inch diameter cylindrical strands ir a screw
extruder and was allowed to dry. Approximately lO g of the
dried extrudate was calcined in air at 600-C with lO~ steam
for lO hours to produce the desired iron containing
catalyst, Catalyst J. The iron loading of this catalyst is
about 2 wt.~.
Exam~le 27
Catalytic evaluation of Catalyst J
In this example, the SCR activity of Catalyst J from
ExaDple 26 was evaluated using similar equipment and the
same procedure as Example 3. Catalyst activity results are
reported below in Table 15.
2 t 93~51
~ WO961~1689 r~l,u~
-Z7-
Table 15
Percent N in Feed Converted to N2
~em~erature. ~C Catalyst J
550 74%
455 97%
400 100%
345 99%
250 88%
Examl~le 28
Comparative testing after steaming
In this example, the SCR activity of the base HZSM-5
and Catalysts H, I, and J are compared after each of the
catalyst were treated with 100% steam at 700~C for 7 hours.
The catalyst samples were evaluated using similar equipment
and the same procedure as Example 3. Catalyst activity
results are reported below in Table 16.
Table 16
Percent N in Feed Converted to N2
Steamed Catalvsts
Tem~.. ~C Base Catalvst Catalvst H CatalYst I CatalYst J
550 56% 92% 98% 92%
455 46~100% 98% 100%
400 36%100% 97% 100%
345 zo%1~0% 99% 100%
250 6% 96% 77% 95%
Exam~le 29
An iron containing ZSM-5 catalyst was prepared by the
following method: Approximately 1.5g of iron (III) nitrate
was dissolved in 6.5g distilled water. This solution was
_ _ _ _ _ _ _ _ _ _ _ _ _ , .. . . .. . . . . . . . . .
21 93951
W0~6~l6
-28-
added to about lOg of the base HZSM-5 and the resulting
slurry was mixed and dried at room temperature overnight.
The dried inpregnated solid was then calcined in air at
600-C with 10% steam for 10 hours to produce the desired
catalyst, Catalyst R. The nominal iron loading of this
sample is about 2 wt%.
Exam~le 30
In this example, the SCR activity of Catalyst R from
Example 29 was evaluated using similar equipment and the
same reaction conditions as Example 3. See Table 17 below.
Table 17
Percent N in Feed Converted to N2
Temperature, 'C Catalyst K
550 86~
455 97%
400 99%
345 99%
250 92%
Exam~le 31
In this example Catalyst K was hydrothermally
treated at 850-C in air containing 20% steam for 6 hours.
This catalyst is re~erred to as Catalyst L.
~Y~le 32
In this example, the SCR activity of the
hydroth~rr=lly treated cdtalyst~ Cataly5t L, from Ex~mple
31 was evaluated using similar equipment the same reaction
conditions as Example 3. Catalyst activity results are
reported below in Table 18.
21 93q51
~ W096l0l689 l~ll. .
-29-
TAhle 18
Percent N in Feed Converted to N2
Temperature, ~C Hydroth~rr-lly
treated
Catalyst L
550 ~ g6%
455 g9%
400 9g%
345 99
250 96
EYAmnle 33
In this example the hydrothermally treated catalyst,
Catalyst L, from Example 31 was aged at 700-C in 100% steam
for 7 hours. This catalyst is referred to as Catalyst M.
Exa~le 34
In this example, the SCR activity of the aged,
hydro~h~r~lly treated catalyst, Catalyst M, from Example
33 was evaluated using similar equipment and the same
reaction conditions as Example 3. Catalyst activity
results are reported below in Table 19.
Table 19
Percent N in Feed Converted to N2
Temperature, ~C Aged Catalyst
o~ Example 33
550 99~
455 96%
400 95%
345 93%
250 82~
WO9610168g 21~3~51 p ,,~ ~
-30-
Exam~le 35
In this example the aged, hydrothermally treated
catalyst, Catalyst ~, from Example 33 was further aged at
900-C in lO0~ steam for 7 hours. This catalyst is referred
to as Catalyst N.
ExamPle 36
In this example, the SCR activity of the aged,
hydrothermally treated catalyst, Catalyst N, from Example
35 was evaluatad using similar equipment and the same
reaction conditions as Example 3. Catalyst activity
results are reported below in Table 20.
Table 20
Percent N in Feed Converted to N2
Temperature, ~C Aged Catalyst
of Example 35
550 86~
455 71%
ioo 53%
345 28%
250 ll~
ExamPle 37
In this example Catalyst K was aged at 700 C in 100%
steam for 7 hours without the intermediate hydrothermal
treatment. This catalyst will be referred to as Catalyst
0.
Exa~le 38
In this example, the SCR activity of the aged
catalyst, Catalyst 0 from Example 37 was evaluated using
similar equipment and the same reaction conditions as
Example 3. Catalyst activity results are reported below in
Table 21.
.. ..... .. _ _ _ _ _ . _
21 93951
~ W096l0~689 ~1/ L ~!,.l
-31-
Table 21
Percent N in Feed Converted to N2
T~ tUL~, ~C Aged Catalyst
of Example 37
550 98%
455 98%
400 97%
345 99%
250 77%
Exam~le 39
In this example the aged catalyst, Catalyst 0, from
Example 37 was further aged at 900-C in 100% steam for 7
hours. This catalyst will be referred to as Catalyst P.
Exam~le 40
In this example, the SCR activity of the twice-aged
catalyst, Catalyst P, from Example 39 was evaluated using
similar equipment and the same reaction conditions as
Example 3. Catalyst activity results are reported below in
Table 22.
Table 22
Percent N in Feed Converted to N2
Temperature, ~C Aged Catalyst
of Example 39
550 56%
455 32%
400 21%
345 14%
250 8%
21 g~q51
WO961~1689 r~a,~
-32-
Exam~le 41
A ZSN-5 catalyst was prepared by the i'ollowing ~ethod:
99 grams of calcined ZSM-5 were mixed in a muller with 20
grams of Dow Corning Q6-2230 silicone resin, and 6.5 grams
of Dow ~ht~ic~l Co. K75M Methocel~. To this dry blend,
52.9 grams of distilled water znd 23.l grams of E. I.
DuPont de Nemours & Co. DBE (dibasic ester) were added
while mulling. The mixture was then extruded to form l/16
inch cylindrical extrudates. The extrudates were dried
overnight at lZO-C and then calcined at 600-C in 10% steam
for lO hours to produce a ZSM-5 containing catalyst. This
catalyst is referred to herein as Catalyst Q.
F~nle 42
An iron containing ZSM-5 sample was prepared by the
following method: 99 grams of calcined ZSM-5 were mixed in
a muller with 20 grams of Dow Corning Q6-2Z30 silicone
resin, 6.5 grams of Dow K75M Methocel~, and 3.2 grams of
iron oxide, Fe20~. To this dry blend, 52.9 grams of
distilled water and 23.l grams of DuPont DBE (dibasic
ester) were added while mulling. The mixture was then
formed into 1~16 inch cylindrical extrudates. The
extrudates were dried overnight at 120-C and then calcined
at 600 C in 10% steam for lO hours to produce an iron
containing catalyst, Catalyst R.
Exam~le 43
In this example, the SCR activity of Catalyst Q is
compared with the SCR activity of Catalyst R. The catalyst
samples were evaluated using a fixed-bed quartz reactor
operating between 250 and 550~C. The reactor was loaded
with 2.75 grams of catalyst with inlet qases consisting of
500 ppm N0, 500 ppm NH3, and 5% 0~ in a N2 carrier flowing
at a constant flow rate of l,ooo cc/min. The effluent from
~ W096l01689 2 1 9395 I p
-33-
the reactor was contin~n~ly monitored by FTIR (Fourier
Transform Infrared) analysis. Catalyst activity results
are summarized below in Table 23.
T~hle 23
Net N0 Conversion, %
Tem~erature. ~CCatalvst 0 CatalYst R
550 71% 92
454 74% 96%
398 72~ 96%
343 60% 96~
250 25% 65%
Exammle 44
An iron containing ZSM-5 sample was prepared by the
following method: 99 grams of calcined ZSM-5 were mixed in
a muller with 20 grams of Dow Corning Q6-2230 silicone
resin, 6.5 grams of Dow ~75M Methocel~, and 0.32 grams of
iron oxide, Fe203. To this dry blend, 52.9 grams of
distilled water and 23.1 grams of DuPont DBE (dibasic
ester) were added while mulling. The mixture was then
formed into 1/16 inch cylindrical extrudates. The
extrudates were dried overnight at 120-C and then calcined
at 600-C in 10~ steam for 10 hours to produce an iron
containing catalyst, Catalyst S.
Exam~le 45
In this example, the SCR activity of Catalyst Q is
compared with the SCR activity of Catalyst S. The catalyst
samples were evaluated using a fixed-bed quartz reactor
operating between 250 and 550-C. The reactor was loaded
with 2.75 grams of catalyst with inlet gases consisting of
WOg6l~l689 2 1 9 3 9 5 ~
-34-
500 ppm N0, 500 ppm NH3, and 5% ~2 in a N2 carrier flowing
at a constant flow rate of 1,000 cc~min. The effluent from
the reactor was continuously monitored by FTIR ~Fourier
Transform Infrared) analysis. Catalyst activity results
are summarized below in Table 24.
T~hle 24
Net N0 Conversion, %
Tem~erature. 'C CatalYst Q CatalYst S
550 71% ~4%
454 74% S6%
398 72% 87
343 60% 82
250 25% 40
~xam~le 46
A component of the in-situ grown ZSM-5 clay aggregate
catalyst precursor was prepared by mixing 140 grams of
calcined ZSM-5 seeds with 1~60 grams of kaolin clay
(Kaopaque lOS, a Georgia kaolin clay, Dry Branch Chemical
Co., Dry Branch, GA). The mixed cu~ olle.lLs will be
referred to herein as Component A.
Exam~le 47
An in-situ grown ZSM-5 clay aggregate catalyst
precursor was prepared by mixing 75.9 grams of Component A
from Example 46 with 7.6 grams of Dow Chemical Co. K75M
Methocel~ in a muller. To this dry blend, 60.3 grams of E.
I. DuPont de Nemours & Co. Ludox~ AS-40 colloidal silica
were added while mulling. The mixture was then extruded
into 1/16 inch cylindrical extrudates. The extrudates were
dried overnight at 120-C and then calcined at lOlO-C for 3
hours to produce an in-situ grown ZSM-5 catalyst precursor,
Precursor A.
... .. . , . . , _ _ _ _ _ . _
2 1 9395 1
~ WO96tO1689
-35-
Exam~le 48
An iron containing in-situ grown ZSM-5 clay aggregate
catalyst ~e~ul~oI was prepared by mixing 75.9 grams of
C~ J~L A from Example 46 with 7.6 grams of Dow ~75M
Methocel~ and 3.6 grams of Fe203 in a muller. To this dry
blend, 60.3 grams of DuPont Ludox~ AS-40 colloidal silica
were added while mulling. The mixture was then extruded
into 1/16 inch cylindrical extrudates. The extrudates were
dried overnight at 120-C and then calcined at 1010-C for 3
hours to produce an in-situ grown ZSM-5 catalyst precursor,
Precursor B.
Exammle 49
An in-situ grown ZSM-5 catalyst was prepared by the
following method: 100 grams of Precursor A from Example 47
were placed in the bottom of a 1 liter autoclave with 384
grams of water, 16.1 grams of a 50% NaOH solution, and 5.9
grams of n-propylamine. Crystallization was completed
under autog~nollq pressure at 149-C for 6 hours with no
additional nutrients. After synthesis, the extrudates were
cooled to room temperature, washed and dried at 120-C. The
extrudates were NH~t exchanged three times. A hybrid
calcination followed which consisted of three hours in
nitrogen at 482-C, with air slowly bled in to minimize the
exotherm, then the temperature was raised to 537 C and held
for six hours to produce an in-situ grown ZSM-5 catalyst,
Catalyst T (greater than about 30% crystallinity).
Exam~le 50
An in-situ grown iron-containing ZSM-5 catalyst that
should be effective in the mcthod of this invention may be
- prepared by the following method: about 100 grams of
Precursor B from Example 48 may be placed in the bottom of
a 1 liter autoclave with about 384 grams of water, about
16.1 grams of a 50% NaOH solution, and about 5.9 grams of
n-propylamine. Crystallization should be possible by
treating the mixture under autogenous pressure at about
2 1 ~3~5 1
WO96/01689 I~
-36-
149-C for about 6 hours with no additional nutrients.
After cynthesis, the extrudates may be cooled to room
t , ~LULe~ and then may be washed and may be dried at
120-C. The extrudates should be NH~ ~Yrh~ngr~ three times.
The illm exchanged extrudates may be hybrid ralcinr~d~
by treating them for about three hours in nitrogen at about
482-C, and then by slowly bleeding air in to m;nimize the
exotherm that may be developed, then raising the
temperature to 537"C and holding the extrudates at that
temperature for about six hours.
-
