United States Patent [191
`Byrne
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,961,917
`Oct. 9, 1990
`
`[54] METHOD FOR REDUCTION OF NITROGEN
`OXIDES WITH AMMONIA USING
`PROMOTED ZEOLITE CATALYSTS
`
`[75] Inventor: John W. Byrne, Edison, N .J .
`[73] Assignee: Engelhard Corporation, Edison, NJ.
`[21] Appl. No.: 341,405
`[22] Filed:
`Apr. 20, 1989
`[51] Int. Cl.5 ........................ .. B01J 8/00; C01B 21/00
`[52] U.S. Cl. .................................................. .. 423/239
`[58] Field of Search ................. .. 423/239 A, 239, 235,
`.
`423/235 D
`References Cited
`U.S. PATENT DOCUMENTS
`
`[56]
`
`3,895,094 ' 7/1975 Carter et al. ...................... .. 423/239
`4,104,361 8/ 1978 Nishikawa et a1
`423/239
`4,220,632 9/1980 Pence et al. .
`423/239
`4,473,535 9/1984 Kittrell et al.
`423/239
`4,735,927 4/1988 Gerdes et a1. ..................... .. 423/239
`Primary Examiner-Gregory A. Heller
`[57]
`ABSTRACT
`A method in accordance with the invention comprises
`
`passing through a zeolite catalyst as described below, a
`gaseous stream containing nitrogen oxides, ammonia
`and oxygen to selectively catalyze the reduction of
`nitrogen oxides and, if excess or unreacted ammonia is
`present, to oxidize the excess of unreacted ammonia
`with oxygen to hydrogen and water. The method in
`cludes the use of a zeolite catalyst composition which
`comprises a metal (e.g., iron or copper) promoted zeo
`lite, the zeolite being characterized by having a silica to
`alumina ratio of at least about 10 and a pore structure
`which is interconnected in all three crystallographic
`dimensions by pores having an average kinetic pore
`diameter of at least about 7 Angstrorns. Promoted zeo
`lites of the above type have demonstrated high toler
`ance for sulfur poisoning, good activity for the selective
`catalytic reduction of nitrogen oxides with ammonia,
`good activity for the oxidation of ammonia with oxy
`gen, and the retention of such good activities even
`under high temperature operations, e.g., 400° C. or
`higher, and hydrothermal conditions.
`
`7 Claims, 2 Drawing Sheets
`
`Umicore AG & Co. KG
`Exhibit 1110
`Page 1 of 10
`
`

`

`US. Patent Oct.9, 1990
`
`Sheet 1 0f 2
`
`I00“
`
`90
`
`80
`
`U 2.8 Fe BETA
`
`o 2.5 CU BETA
`
`>< 4.4 Fe BETA‘
`
`360
`
`560
`450
`460
`350
`INLET GAS TEMPERATURE-“c
`Figs. I
`
`5:50
`
`sbo
`
`250
`
`l
`
`300
`
`l
`
`450
`460
`350
`INLET GAS TEMPERATURE-°C
`
`560
`
`550
`
`o AGED
`
`C’ FRESH
`
`Umicore AG & Co. KG
`Exhibit 1110
`Page 2 of 10
`
`

`

`US. Patent Oct.9, 1990
`
`Sheet 2 0f 2
`
`4,961,917
`
`2 30-
`°\°
`
`D
`
`250
`
`300
`
`4:50
`460
`3'50
`INLET GAS TEMPERATURE-"c
`FIG. 3
`
`HOURS OF
`AGING
`00
`B840
`
`560
`
`550
`
`(0 O J
`0:) O |
`
`FIG. 4
`
`o
`
`
`
`% NO CONVERSION
`
`
`
`[\J ()1 b <2 9 <2
`
`0 4.4'Fe BETA
`
`K3‘
`
`o NH4 BETA
`
`O
`I
`250
`
`I
`300
`
`I
`350
`
`460
`
`I
`450
`
`560
`
`In
`550
`
`600
`
`INLET GAS TEMPERATURE-"c
`
`Umicore AG & Co. KG
`Exhibit 1110
`Page 3 of 10
`
`

`

`1
`METHOD FOR REDUCTION OF NITROGEN
`OXIDES WITH AMlVIONIA USING PROMOTED
`ZEOLITE CATALYSTS
`
`5
`
`4,961,917
`2
`silica to alumina ratio greater than 10, preferably
`greater than 20 (column 6, lines 23-28). Representative
`high-silica zeolites are described at columns 6-8 of the
`patent and include (column 6, lines 29-33) silicalite (as
`described in U.S. Pat. No. 4,061,724), ZSM-S, ZSM-S,
`ZSM-ll, ZSM-12, hyper Y, ultrastabilized Y, Beta,
`mordenite and erionite. Ultrastabilized Y is described
`(column 7, lines 22-25) as “a form of zeolite Y which
`has been treated to give it the organophilic characteris
`tic of the adsorbents of the present invention.” Example
`6 of the patent is stated to show no measureable loss in
`combustion activity of the copper-promoted zeolite
`catalyst due to sulfur poisoning (exposure of the catalyst
`to methylmercaptan in the gaseous stream). The patent
`thus discloses the utility of the copper-promoted speci
`?ed zeolites for three-way conversion in an exhaust gas
`generated by a lean air to fuel ratio combustion mixture.
`The art thus shows an awareness of the utility of
`metal-promoted zeolite catalysts including, among oth
`ers, iron-promoted and copper-promoted zeolite cata
`lysts, for the selective catalytic reduction of nitrogen
`oxides with ammonia.
`
`40
`
`50
`
`BACKGROUND OF THE INVENTION
`1. Field of The Invention
`The present invention is concerned with a method of
`catalyzing the reduction of nitrogen oxides with ammo
`nia, especially the selective reduction of nitrogen ox
`ides with ammonia in the presence of oxygen, using
`zeolite catalysts, especially metalpromoted zeolite cata
`lysts.
`2. The Related Art
`Both synthetic and natural zeolites and their use in
`promoting certain reactions, including the selective
`reduction of nitrogen oxides with ammonia in the pres
`ence of oxygen, are well known in the art. Zeolites are
`aluminosilcate crystalline materials having rather uni
`form pore sizes which, depending upon the type of
`zeolite and the type and amount of cations included in
`the zeolite lattice, range from about 3 to 10 Angstroms
`in diameter.
`'
`Japanese Patent Publication (Kokai) No. 51-69476,
`published Jun. 16, 1976 on Application No. 49-142463,
`?led Dec. 13, 1974, discloses a method for reducing
`nitrogen oxides in waste gases by reaction with ammo
`nia in the presence of a metal-promoted, dealuminized
`synthetic or natural mordenite zeolite. The resistance of
`the catalyst to sulfurous poisons, particularly sulfur
`trioxide and sulfuric acid mist, is said to be enhanced by
`dealuminizing the mordenite to increase the silica to
`alumina ratio to more than 12, preferably to more than
`15. The zeolite is promoted with 0.5 to 30 weight per
`cent of at least one of a number of promoters including
`copper, vanadium, chromium, iron, cobalt or nickel and
`used at a reaction temperature of 200° to 500° C. with
`from 0.5 to three times the stoichiometric amount of
`ammonia reductant. Example 1 of the Publication illus
`trates an iron-promoted mordenite ore as being effec
`tive for the reduction of nitrogen oxides. In connection
`with Example 2, it is stated that a slight decrease of the
`activity of a high silica to alumina ratio, copper-pro
`moted mordenite catalyst is recognized when sulfur
`trioxide is included in the gasstream. However, an
`“extreme improvemen ” of resistance to sulfur trioxide
`poisoning is noted in comparison with a copper mor
`denite which has not been dealuminized to increase the
`silica to alumina ratio.
`UK patent application No. 2,193,655A discloses a
`catalyst containing a low surface area titania and a cop
`per-promoted zeolite for use in the reduction of nitro
`gen oxides with ammonia. The zeolite has an average
`pore diameter of 10 Angstroms or less, preferably 8
`Angstroms or less, and a silica to alumina molar ratio of
`10 or more, preferably 20 or more; the resultant titania/
`promoted zeolite catalysts having these characteristics
`are stated to have good mechanical strength and to be
`resistant to volatile catalyst poisons such as arsenic,
`selenium, tellurium, etc., contained in exhaust gases.
`Examples of suitable zeolites are mordenite, ZSM-S,
`and ferrierite.
`U.S. Pat. No. 4,297,328 discloses a “three-way con
`version” catalytic process for the simultaneous catalytic
`oxidation of carbon monoxide and hydrocarbons and
`reduction of nitrogen oxides for purifying the exhaust
`gas of automobile engines operated within a prescribed
`range of air to fuel ratio (column 4, lines 63-68). The
`’ disclosed catalyst is a copper-promoted zeolite having a
`
`SUMMARY OF THE INVENTION
`In accordance with the present invention, there is
`provided a method for the reduction of nitrogen oxides
`with ammonia, the method comprising the following
`steps. A gaseous stream containing nitrogen oxides and
`ammonia, and which may also contain oxygen, is con
`tacted at a temperature of from about 250° C. to 600° C.
`with a sulfur-tolerant catalyst composition. The catalyst
`composition comprises a zeolite having a silica to alu
`mina ratio of at least about 10, and a pore structure
`which is interconnected in all three crystallographic
`dimensions by pores having an average kinetic pore
`diameter of a least about 7 Angstroms, e.g., from about
`7 to 8 Angstroms, and one or both of an iron and a
`copper promoter present in the zeolite, for example, in
`the amount of from about 0.1 to 30 percent by weight,
`preferably from about 1 to 5 percent by weight, of the
`total weight of promoter plus zeolite.
`Another aspect of the invention provides that the
`promoter is an iron promoter.
`Still another aspect of the present invention provides
`that the zeolite comprises one or more of USY, Beta and
`ZSM-20. A refractory binder may be admixed with the
`zeolites.
`The gaseous stream may contain from about 0.7 to 2
`moles of ammonia per mole of nitrogen oxides. Oxygen
`may also be present in the gaseous stream in an amount
`of from about 0.5 to 30 volume percent of the gaseous
`stream.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a plot showing the percent conversion of
`NO versus inlet temperature for various metal-pro
`moted zeolite catalysts;
`FIG. 2 is a plot showing the percent conversion of
`NO versus the inlet temperature of a gaseous stream to
`be treated for aged and fresh copper-promoted zeolite
`catalysts;
`FIG. 3 is a plot showing the percent conversion of
`NO versus inlet temperature of a gas stream passed
`through aged and fresh iron promoted beta zeolite cata
`lysts; and
`
`60
`
`65
`
`Umicore AG & Co. KG
`Exhibit 1110
`Page 4 of 10
`
`

`

`4,961,917
`3
`FIG. 4 is a plot showing the percent conversion of
`ammonia versus inlet temperature of a gas stream fed to
`different beta zeolite catalysts.
`References herein and in the claims to a zeolite cata
`lyst containing a percent “by weight” promoter means
`a percentage calculated as the weight of promoter, as
`the metal, divided by the combined weights of pro
`moter (as the metal) plus the zeolite.
`Reference herein and in the claims to “metal”, “iron”
`and “copper” with respect to the promoters should not
`be taken to imply that the promoter is necessarily in the
`elemental or zero valence state; the terms enclosed in
`quotes should be understood to include the presence of
`promoters as they exist in the catalyst compositions,
`e.g., as exchanged ions and/or impregnated ionic or
`other species.
`
`20
`
`25
`
`DETAILED DESCRIPTION OF THE
`INVENTION AND PREFERRED
`EMBODIMENTS THEREOF
`In order to reduce the emissions of nitrogen oxides
`from ?ue and exhaust gases, such as the exhaust gener
`ated by gas turbine engines, ammonia is added to the
`gaseous stream containing the nitrogen oxides and the
`gaseous stream is then contacted with a suitable catalyst
`at elevated temperatures in order to catalyze the reduc
`tion of nitrogen oxides with ammonia. Such gaseous
`streams often inherently contain substantial amounts of
`oxygen. For example, a typical exhaust gas of a turbine
`engine contains from about 2 to 15 volume percent
`oxygen and from about 20 to 500 volume parts per
`million nitrogen oxides, the latter normally comprising
`a mixture of NO and N02. Usually, there is suf?cient
`oxygen present in the gaseous stream to oxidize residual
`ammonia, even when an excess over the stoichiometric
`amount of ammonia required to reduce all the nitrogen
`oxides present is employed. However, in cases where a
`very large excess over the stoichiometric amount of
`ammonia is utilized, or wherein the gaseous stream to be
`treated is lacking or low in oxygen content, an oxygen
`containing gas, usually air, may be introduced between
`the ?rst catalyst zone and the second catalyst zone, in
`order to insure that adequate oxygen is present in the
`second catalyst zone for the oxidation of residual or
`excess ammonia. The reduction of ammonia with nitro
`gen oxides to form nitrogen and H20 can be catalyzed
`by metal-promoted zeolites to take place preferentially
`to the oxidation of ammonia by the oxygen, hence the
`process is often referred to as the “selective” catalytic
`reduction (“SCR”) of nitrogen oxides, and is sometimes
`referred to herein simply as the “SCR” process.
`The catalysts employed in the SCR process ideally
`should be able to retain good catalytic activity under
`high temperature conditions of use, for example, 400° C.
`or higher, under hydrothermal conditions and in the
`presence of sulfur compounds. High temperature and
`hydrothermal conditions are often encountered in prac
`tice, such as in the treatment of gas turbine engine ex
`hausts. The presence of sulfur or sulfur compounds is
`often encountered in treating the exhaust gases of coal
`fred power plants and of turbines or other engines
`fueled with sulfurcontaining fuels such as fuel oils and
`the like.
`Theoretically, it would be desirable in the SCR pro
`cess to provide ammonia in excess of the stoichiometric
`amount required to react completely with the nitrogen
`oxides present, both to favor driving the reaction to
`completion and to help overcome inadequate mixing of
`
`4
`the ammonia in the gaseous stream. However, in prac
`tice, signi?cant excess ammonia over the stoichiometric
`amount is normally not provided because the discharge
`of unreacted ammonia from the catalyst would itself
`engender an air pollution problem. Such discharge of
`unreacted ammonia can occur even in cases where am
`monia is present only in a stoichiometric or sub-stoichi
`ometric amount, as a result of incomplete reaction and
`/or poor mixing of the ammonia in the gaseous stream.
`Channels of high ammonia concentration are formed in
`the gaseous stream by poor mixing and are of particular
`concern when utilizing catalysts comprising monolithic
`honeycomb-type carriers comprising refractory bodies
`having a plurality of fine, parallel gas flow paths extend
`ing therethrough because, unlike the case with beds of
`particulate catalysts, there is no opportunity for gas
`mixing between channels. It is therefore also desirable
`that the catalyst employed to catalyze the selective
`catalytic reduction of nitrogen oxides, be effective to
`catalyze the reaction of oxygen and ammonia, in order
`to oxidize excess or unreacted ammonia to N2 and H20.
`The present invention is predicated on the discovery
`that a certain class of zeolites, especially when pro
`moted with a promoter such as iron or copper, espe
`cially iron, exhibits desired characteristics as described
`above by providing a sulfur tolerant catalyst which
`shows good activity for both (1) the selective catalytic
`reduction of nitrogen oxides by reaction with ammonia,
`even in the presence of oxygen, and (2) the oxidation of
`ammonia with oxygen when nitrogen oxides are at very
`low concentrations. The catalysts of the present inven
`tion retain such activity even after prolonged exposure
`to high temperatures, hydrothermal conditions, and
`sulfate contamination of the type often encountered in
`use, e.g., in the treatment of coal-?red power plants or
`turbine engine exhaust gases.
`Generally, in accordance with the practices of the
`present invention, a catalyst is provided which com
`prises a zeolite having speci?c properties as described
`below, and which is promoted by a metal, preferably
`iron, in order to enhance its catalytic activity. The zeo
`lite may be provided in the form of a ?ne powder which
`is admixed with or coated by a suitable refractory
`binder, such as bentonite or silica, and formed into a
`slurry which is deposited upon a suitable refractory
`carrier. Typically, the carrier comprises a member,
`often referred to as a “honeycomb” carrier, comprising
`one or more refractory bodies having a plurality of ?ne,
`parallel gas ?ow passages extending therethrough. Such
`carriers are, of course, well known in the art and may be
`made of any suitable material such as cordierite or the
`like. The catalysts of the present invention may also be
`provided in the form of extrudates, pellets, tablets or
`particles of any other suitable shape, for use as a packed
`bed of particulate catalyst, or as shaped pieces such as
`plates, saddles, tubes or the like.
`The catalysts of the present invention show a marked
`resistance to poisoning by sulfates (or other sulfur com
`pounds) which are often contained in the gas streams
`which are treatable by the catalysts of the present in
`vention. Without wishing to be bound by any particular
`theory, it appears that SO; poisoning has both short
`term and long term effects. For example, ?owing a gas
`stream containing 2,000 parts per million by volume
`(“Vppm”) S02 through catalysts comprising copper
`promoted small to medium pore zeolites such as ZSM-S,
`naturally occurring chabazite and clinoptilolite, re
`sulted in 10 to 40 percent reduction in SCR process
`
`40
`
`45
`
`55
`
`60
`
`Umicore AG & Co. KG
`Exhibit 1110
`Page 5 of 10
`
`

`

`20
`
`25
`
`4,961,917
`5
`6
`activity. Even at $0; levels as low as 130 Vppm S02,
`more or less regularly recurring connections, intersec
`signi?cant activity reduction for the SCR process was
`tions and the like. Pores having a particular characteris
`noted for such catalysts. On the other hand, larger pore
`tic, such as a given dimension diameter or cross-sec
`zeolites such as Y, L and USY exhibited no short-term
`tional con?guration, are said to be one dimensional if
`S02 susceptibility. With operating temperatures at
`those pores do not intersect with other like pores. If the
`about 350‘ C., the short-term S02 poisoning effect on a
`pores intersect only within a given plane with other like
`copper-promoted mordenite was shown to be revers
`pores, the pores of that characteristic are said to be
`ible. Thus, when the supply of S0; to the test gas stream
`interconnected in two (crystallographic) dimensions. If
`passing through the copper-promoted mordenite cata
`the pores intersect with other like pores lying both in
`lyst was turned off, the activity for catalytic reduction
`the same plane and in other planes, such like pores are
`of NO immediately returned to the same level attained
`said to be interconnected in three dimensions, i.e., to be
`by the catalyst prior to introducing the S02. Appar
`“three dimensional”. It has been found that zeolites
`ently, S02 is absorbed, but not tightly bound in the
`which are highly resistant to sulfate poisoning and pro
`zeolite pores. In the case of the small to medium pore
`vide good activity for both the SCR process and the
`zeolites, this competition absorption with NH3 and NO
`oxidation of ammonia with oxygen, and which retain
`probably results in a physical blockage and/or diffu
`good activity even when subject to high temperatures,
`sional restriction.
`hydrothermal conditions and sulfate poisons, are zeo
`On the other hand, when zeolite catalysts are sub
`lites which have pores which exhibit a pore diameter of
`jected to higher S02 concentrations for longer periods
`at least about 7 Angstroms and are interconnected in
`of time, such as 5,000 Vppm S0; for protracted periods,
`three dimensions. Without wishing to be bound by any
`such as overnight, a 15 to 25 percent activity reduction
`speci?c theory, it is believed that the interconnection of
`for the SCR process was noted for copper promoted,
`pores of at least 7 Angstroms diameter in three dimen
`synthetic iron-free zeolites. A 60 percent reduction in
`sions provides for good mobility of sulfate molecules
`SCR process activity is typical for Fe2O3 containing
`throughout the zeolite structure, thereby permitting the
`natural chabazite. Similar results were sustained with
`sulfate molecules to be released from the catalyst to free
`iron promoted mordenite catalysts.
`a large number of the available adsorbent sites for reac
`Even at lower levels of S02 concentration, similar to
`tant NOx and NH; molecules and reactant NH; and O;
`those likely to be encountered in commercial opera
`molecules. Any zeolites meeting the foregoing criteria
`tions, a permanent activity loss for the SCR process is
`are suitable for use in the practices of the present inven
`shown by many zeolite catalysts. For example, a cop
`tion; speci?c zeolites which meet these criteria are
`per-promoted mordenite catalyst was subjected over
`USY, Beta and ZSM-20. Other zeolites may also satisfy
`night to passage through it of a gaseous stream contain
`the aforementioned criteria.
`ing 540 Vppm S02, and showed a permanent activity
`A number of tests were conducted in order to evalu
`loss comparable to that described above for the cata
`ate the catalytic activity and selectivity for the SCR
`lysts subjected to the 5000 Vppm sOz-containing gas.
`process and ammonia oxidation, of both fresh and aged
`For zeolites with silica-to-alumina ratios of less than
`catalysts comprising iron promoted zeolites and copper
`10, the activity loss appears to be associated with insuf
`promoted zeolites. All the catalysts employed in these
`ficient stability under the simulated acidic aging condi
`tests were prepared from the same NH4+form of Beta
`tions. As indicated by the prior art noted above, the
`zeolite powder, which was synthesized as described in
`utilization of high ratios of silica to alumina is known to
`the following Example 1.
`enhance acid resistance of the zeolite and to provide
`Reference is made below to the weights of solids
`enhanced resistance of the zeolite to acid sulfur poison
`being on a “vf basis”. The term in quotes means a vola
`ing. Generally, silica to alumina ratios well in excess of
`tiles-free basis, and is used to indicate the weight that
`the minimum of 10 may be employed. Conversion ef?
`the solid in question would have if it were calcined at
`ciencies of 90 to 93% for NO,, reduction with ammonia
`45
`1000“ C. to drive off volatiles. Thus, if 10.1 grams of a
`have been attained with fresh copper promoted Beta
`substance contains 0.1 gram of such volatiles, the 10.1
`zeolites having silica to alumina ratios of 20, 26, 28, 37
`grams is reported as “10 grams (vf basis)”. Unless spe
`and 62. A conversion efficiency of 77% was attained by
`ci?cally otherwise stated, all percentages by weight
`a fresh copper promoted ZSM-5 zeolite having a silica
`herein and in the claims are on a vf basis.
`to alumina ratio of 46. However, fresh copper promoted
`USY zeolites with silica to alumina ratios of, respec
`tively, 8 and 30 provided 85% and 39% conversions of
`NOX, suggesting that at least for USY, silica to alumina
`ratios should be signi?cantly less than 30.
`However, resistance to short term sulfur poisoning
`and the ability to sustain a high level of activity for both
`the SCR process and the oxidation of ammonia by oxy
`gen has been found to be provided by zeolites which
`also exhibit pore size large enough to permit adequate
`movement of the reactant molecules NO and NH3 in to,
`and the product molecules N2 and H20 out of, the pore
`system in the presence of sulfur oxide molecules result
`ing from short term sulfur poisoning, and/or sulfate
`deposits resulting from long term sulfur poisoning. The
`pore system of suitable size is interconnected in all three
`65
`crystallographic dimensions. As is well known to the
`those skilled in the zeolite art, the crystalline structure
`of zeolites exhibits a complex pore structure having
`
`EXAMPLE 1
`I. Synthesis of Batch 1:
`A. The following materials were combined in a 100
`gallon, titanium lined, autoclave reactor and stirred
`suf?ciently to maintain the solids in suspension:
`1. 18.28 Kg of Hi-sil ® #233 silica powder
`2. Suf?cient amounts of each of the following to
`result in molar ratios of SiO2, NazO, H20, and
`(T etraethylammoniumhO to A1203 of 23.1, 1.94,
`767, and 1.62, respectively:
`a. Nalco sodium aluminate solution (20.9% A1
`203,
`N820, 54.0% H20)
`b. 40% solution of Tetraethylammonium hy
`droxide (TEAOH)
`c. Deionized water
`B. To the mixture obtained in step A was added 1.38
`Kg (vf basis) of zeolite Beta powder.
`
`35
`
`40
`
`55
`
`Umicore AG & Co. KG
`Exhibit 1110
`Page 6 of 10
`
`

`

`4,961,917
`
`10
`
`7
`8
`C. The reactor was sealed and heated to 150° C. with
`EXAMPLE 2
`continued stirring.
`I. A portion of the NH4+ Beta powder of Example 1
`D. After 6 days at 150° C. the reactor was cooled to
`room temperature and three separate batches as the
`was promoted with iron as follows.
`A. 8.35 Kg (vf) of the NH4+ Beta exchanged powder
`slurry contained in the reactor were ?ltered in a 5
`was combined (with stirring) with an aqueous solu
`twelve inch square ?lter press to separate the solids
`tion of Fe2(SO4)3 that contained 3% by weight Fe.
`from the reaction liquor. The solids from the ?rst
`A ratio of 2.5 parts by weight of solution per part
`two ?lter batches were not washed, while the
`by weight of NH4+ Beta powder (on a vf basis)
`solids from the third batch was‘ washed with sev-
`was used.
`eral gallons of deionized water.
`B. With continued stirring, the slurry of Step A was
`E. The resultant ?lter cakes were combined and dried
`heated to 82° C. for one hour, and then cooled.
`at 100° C. Next, a 13.0 Kg batch of the dried solids
`C. The cooled slurry of Step B was then vacuum
`was calcined for 1 hour at 316° C. followed by 1
`?ltered and washed with a equal volume of deion
`hour at 593° C. The resultant calcined powder,
`ized water.
`which was designated Batch 1, had a molar SiOg- 15
`D. The ?lter cake of Step C was dried at 100° C. to
`/Al203 ratio of 17/1 (by chemical analysis) and a
`provide an iron-promoted Beta powder, designated
`BET surface area of 562 m2/ g. Analysis by x-ray
`Fe Beta 1.
`diffraction showed the characteristic peaks associ-
`B. Chemical analysis of Fe Beta 1 showed that it
`ated with Beta zeolite.
`contained 2.78% iron (expressed as the metal on a
`II. Synthesis of Batch 2:
`vf basis).
`A. Step A of the procedure used to prepare Batch 1
`was repeated, except that 36.56 Kg of Hi-sil ® F. One half of the Fe Beta 1 had additional Fe added
`#233 silica powder and suf?cient amounts of the
`to it, using the same procedure described in steps
`same materials as used in Step A of the preparation 25
`A-D above, except that the iron sulfate solution
`of Batch 1 were used to result in molar ratios of
`contained only 1.5% by weight Fe. After drying,
`SiO2, NazO, H20, and (T etraethylammonium)2O
`this material was calcined for 2 hours at 538° C. to
`to A1203 of 23.1, 1.94, 383, and 1.62 respectively.
`provide an iron promoted Beta powder designated
`B. To the mixture obtained in Step A was added 2.76
`Fe Beta 2.
`Kg (vf basis) of zeolite Beta powder of Batch 1.
`G. Chemical analysis of Fe Beta 2 showed that it
`C. The reactor was sealed and heated to 150‘ with
`contained 4.42% iron (expressed as the metal on a
`continued stirring.
`vf basis).
`D. After 6 days at 150° C. the reactor was cooled to
`The Nl-La,+ Beta of Example 4 was used to prepare
`room temperature and batches of the slurry con
`copper promoted zeolite catalysts, as shown in the fol
`lowing Example 3.
`tained therein were ?ltered in a twelve square inch 35
`?lter press to separate the solids from the reaction
`liquor. All the solids obtained were washed by
`passing deionized water through the ?lter cake.
`E. The resultant ?lter cake solids were combined and
`dried at 100° C. A 26.4 Kg (vf basis) batch of the
`dried solids was calcined for 1 hour at 316° C., 40
`followed by 1 hour at 593° C. The resultant cal-
`cined powder, which was designated Batch 2, had
`a molar SiOg/AlgO; ratio of 18/1 (by chemical
`analysis) and a BET surface area of 577 mZ/g. 45
`Analysis by x-ray diffraction showed the charac-
`teristic peaks associated with Beta zeolite.
`III. A master lot of zeolite Beta was made by combining
`7.7 Kg of the Batch 1 powder and 26.4 Kg of the
`Batch 2 powder. The resultant 34.1 Kg master lot of 50
`zeolite Beta was NH4+ion exchanged, as follows.
`A. A solution was prepared by mixing 51.1 Kg of
`54% NH4NO3 solution with 68.1 Kg of deionized
`water.
`B. To the solution of Step A was added the master lot 55
`of Beta powder, with stirring sufficient to suspend
`the solids.
`C. The pH of the suspension of Step B was adjusted
`from 3.9 to 3.15 using 484 g of concentrated HNO3,
`and the slurry was heated to 82° C.
`D. After 30 minutes at 82° C., the slurry was cooled,
`and then ?ltered on a vacuum ?lter to separate the
`solids from the spent exchange solution and pro-
`vide an NH4+ Beta powder, designated NH4+
`Beta. N820 analysis was 0.47% by weight, vf basis. 65
`The resultant NH4+ Beta was used to prepare iron
`promoted zeolite catalysts, as shown in the following
`Example 2.
`
`EXAMPLE 3
`A portion of the NH4+ Beta powder of Example 1
`was promoted with copper as follows:
`A. 25.0 Kg (vf) of the NH4+ Beta powder was added
`to 56.25 Kg of Cu(SO4) solution containing 5% by
`weight Cu, with stirring to suspend the solids and
`disperse the lumps.
`B. With continued stirring, the slurry of Step A was
`heated to 82° C. for one hour, and then cooled.
`C. The cooled slurry of Step B was vacuum ?ltered
`to separate the solids from the liquid, and the solids
`were washed with a volume of deionized water
`equal to the volume of the separated liquid.
`D. The powder of Step C was dried at 100° C. to
`provide a copper promoted Beta powder, desig
`nated Cu Beta 1. Chemical analysis showed that the
`Cu Beta 1 powder contained 3.42% by weight Cu
`(expressed as the metal on a vf basis).
`E. Two-thirds by weight of the Cu Beta 1 dried pow
`der was reslurried (with continuous stirring) in
`deionized water in a ratio of 3 parts by weight of
`water to one part by weight (vf basis) of the Cu
`Beta 1 powder.
`F. After one hour at room temperature, the slurry of
`Step E was vacuum ?ltered to remove the water
`and allowed to air dry overnight.
`G. The powder obtained from Step E was again sub
`jected to the re-slurrying ?ltering and drying of
`Steps E and F, but with a weight ratio of water/
`powder of 2.5/l instead of 3/1.
`H. The air dried ?lter cake obtained from Step G was
`oven dried at 100° C., and then calcined for 2 hours
`
`20
`
`30
`
`60
`
`Umicore AG & Co. KG
`Exhibit 1110
`Page 7 of 10
`
`

`

`4,961,917
`9
`at 538° C. to provide a copper promoted Beta des
`ignated Cu Beta 2.
`I. Chemical analysis of Cu Beta 2 showed that this
`powder contained 2.56% Cu (expressed as the
`metal on a vf basis).
`The NH4+ Beta obtained in Example 1 and the iron (Fe
`Beta 1 and Fe Beta 2) and copper (Cu Beta 1 and Cu
`Beta 2) promoted catalysts obtained in Examples 2 and
`3 were prepared for testing as described in the follow
`ing Example 4.
`
`10
`
`10
`wool to serve as the catalyst bed, and a Vycor
`thermocouple well was positioned just above the
`catalyst bed.
`C. Between 1 and 3 reactors were placed in a reactor
`furnace and connected to the gas supply system.
`D. N2 and air were mixed into a gas containing 10%
`O2 and the balance N2, and this was passed through
`a furnace where it was preheated to 350° C.
`E. The heated gas stream of Step D was then divided
`among the reactors such that each reactor received
`a flow rate of 2 l/min. (for a space velocity of
`l.2>< l06 ccg-lhr-l).
`F. The reactor furnace was then heated to a tempera
`ture nominally 50° C. above the test temperature,
`such that the reactor thermocouples read the nomi
`nal test temperature.
`G. The reaction gases were than added to the inlet
`gas stream in the following amounts:
`1. For SCR testing, 200 parts per million parts by
`volume “Vppm” each of NO and NH3 were
`added to the gas.
`2. For NH3 oxidation activity testing, 200 Vppm of
`NH3 was added to the gas.
`H. After all the ?ows and temperatures had stabi
`lized, the inlet and outlet concentrations of NOX
`and NH3 were measured using a Thermoelectron
`Model 10 NO,, analyzer for both NOX and NH;
`analysis. Periodic NH3 measurements were veri?ed
`using the Draeger tube method.
`I. The gas temperature was then changed, and the
`measurements repeated as in Step H above.
`The results obtained by the tests of Example 5 are plot
`ted in FIGS. 1-4.
`In each of FIGS. 1, 2 and 3 the percentage conver
`sion of nitric oxide (NO) in the test gas is plotted on the
`vertical axis, and the test gas inlet temperature (to the
`catalyst bed) is plotted on the horizontal axis. The nitric
`oxide (NO) content of the test gas is representative of
`nitrogen oxides (NOx) generally, and so reference
`below is made to NO,‘ conversion.
`FIG. 1 compares the NO; SCR process conversion in
`the test gas flowed through beds comprised of fresh
`samples of Cu Beta-2, Fe Beta"1 and Fe Beta 2. In
`FIG. 1, data points for Cu Beta 2 are shown by
`diamonds, for Fe Beta 1 by rectangles and for Fe Beta
`2 by Xs. The data of FIG. show that the copper and
`iron promoted Beta powders have similar SCR activi
`ties and selectivities although, as evidenced by the slight
`conversion d