CA1074081A - Perovskite catalytic compositions having crystal structures and containing metals of the platinum group - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Metal oxides of the type /A11-xA2x//B'1-yMey/O3 having perovakite-type crystal structures in which A1 and A2 are each one or more mono-, di-, or trivalent metals having ionic radii between about 0.8 and 1.65 Angstroms;
B' is one or more metals having ionic radii between about 0.4 and 1.4 Angstroms;
Me is one or more metals of the platinum group (ruthenium, osmium, rhodium, iridium, palladium, and platinum);
x is between about 0.01 and 0.99; and y is between about 0.01 and 0.20 are useful as catalyssts for the oxidation of hydrocarbons and carbon monoxide and for the reduction of nitrogen oxides under conditions typical of those involved in the cleanup of the exhaust gases of internal combustion engines.

Description

BACKG~OUND OF TEE INVENTION
1. Field o~ the Invention Thi5 lnvention relates to novel metal oxldes having perovskite-type cry~tal structures and containing metals Or the platinum group. These o~ides are catalytically active, especially ~n heteroeeneous gas-pha~e reaction~ like those in~olved in the oxidation-reductlon purification o~ the exhaust gases from internal combustion engine~.

2. me Prior Art Much e~rort has been expended in recent year~ in developlng impro~ed heterogeneous catalysts ~or ~he oxidatlon Or volatile carbon compounds in air and for the re*uction Or nitrogen oxldes to nitrogen by hydrogen, carbon mono~ide, and other carbon compounds. Such e~orts haYe been dlrected to~ard the reduct~on of atmospheric pollution by indu6trial processes but have also been largely dlrected to~ard the reductlon of atmospherlc pollution by exhaust gase~ from lnternal combu~tion engine~. Cataly~t~ useful in 8uch proces8es ~ill desirably be low ln cost, selectiv~ in pro tlng deslred oxidation ~nd/or reduction reactlon~ at relatlvely lo~ temperAtures, active ror long perlods at the temperatures involved and in the pre~ence Or the materials incidental to these reactions, simple to pre-pare in suitable form~ having high catalytic activity, active at relatively lo~ surrace areas per unit ~ei8ht of catalytic material, and ~ill al~o dasirably h~e other properties ~ell recogni~ed in the art.
Among the catalytic materials proposed for use ln promoting che~lcal reaction~ such a~ tho~e involved ln the puri~ication Or automotive exh~ust gases are catalysts con-tainlng the platinum metals ruthenium, osmium, rhodium,iridium, palladi~m, and platinum. Such catalytlc materi~ls -2- ~

.

1074~1 are relatively expen~ive; require ~ometime~ impractically large amounts o~ ~carce materlals; frequently must be pre-pared by carerully controlled processes ~or optlmum catalytic activity; are relatively short-llved, apparently because Or eithcr the formation o~ relatlvely volatlle oxldeæ (osmium and ruthenium), becau~e of changes in crystallite particle size or ~urface properties~ or because Or interaction ~ith various components o~ exhaust ga~es in ~ayB ~hich reduce their cata-lytic activity (for instance by rorming catalytically les~
acti~ compounds or alloy8 and by ror~ing volatile halide compounds); and are unsati~f~ctory in other ways.
SUMMARY OF THE INVENTION
me present invention comprises compound~ having cations of metsls in sites of Type A and of Type B with o~ygen lons in the proportions AE03 and having the perovskite crystal structure wherein the ~ites of ~ype A are occupied by catlons of at least two dlf~erent metals having lonlc radii bet~een 0.8 And 1.65A, each belng present ln at least 1% of sald type A sites; from about 1% to 20% o~ the Type B ~ites are occupled by ions of the platinum metals; and the remain-ing Iype B sltes are occupied by ion~ of nonplatinum metals having lonic radil bet~een 0.4 and 1.4A.
Such metal oxlde compounds sre useful as cataly~t~
~or the oxidation o~ carbon monoside and gaseous hydrocarbons and for the reduction Or nltrogen oxides under condltion~
typical Or those involved in the cleanup of the e~h~ust ga~28 rrom lnternal combustion engine~. They are partlcularly attrac-tlve catalysts for the purlfication of ~utomotive e~hau~t ga~s~
becau~e of their relatlvely lo~ cost, ~tability in such e~haust gase~ under o~idizing and reduclng condltlons at high tempera-ture~, 8impllcity in preparat~on ln suitable fo D having high 7~
catalytic activity (even when having relatively low ~urface area~ and when containing relatively small amount~ of expen-~ive metal~), and because they catalyze relatively complete conversion of the obnoxious components of automotive exhaust gases to innocuous substances.
The compounds of thls invention require the presence of platinum group metals (ruthenium, osmium, iridium, rhodium, palladlum and platinum~ occupying from 1~ to 20~ of the Type B
sites, The remaining B sites, which will be called B' sites, are occupied by other, more readily available metals, which can be divided into two broad classes, (1 metal ions which can exist in the perovskite str-~cture in more than one valence and which preferably contribute to the utility of the compounds ~ catalysts (most preferably such metals are present in more than one valence state~ and (2) metal ion~ present in a single fixed valence stRte (~uch as aluminum~ whlch contrlbute mainly to the stability of the compounds~ The compositions necessarily have at least 50~
of the B' ~ites occupied by members of only one of the above cla88e8. Preferably 75~ and most preferably all of the B' qites are occupied by ions of one of the aforesaid cla~ses.
The metal ions occupying B' sites are from groups lA, lB, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6B, 7B, or 8 or from the lanthanlde or actinide rare earth metals and normally have valences one to seven (usually one to five~.
The preferred B' metals having valence one are from groups lA
and lB; those having valence two are from groups lB, 2A, 2B, 3B
6B, 7B, and 8; those having valence three are from groups 3A, 3B, 4B, 5B, 6B, 7B and 8 and the lanthanide and actinide rare earth metals, those havlng valence four are from groups 4A, 4B, 5B, 6B, and 7B or from the transition elements of the first .

~ ~7~

period, and thoQe having valence rive are rrom groups 5A, 5B, 6B and 7B.
One pre~erred class of Bl metsl lon~ are Or tran-sltion metals o~ atomic number 22 to 29 inclw ive ~hlch can e~ist in more than one valence and whereln part Or the B
metal is in one valence ~nd another part is in a second valence. PartlculRrly prererred are iron, nickel and cobalt ~hich are preferably in the trivalent state with from 5% to 50% Or at least one specles in the tetravalent state.
A pre~erred class of io~s having ~i~ed valence ~hlch occupy Bl slte~ are ions o~ the metals of Group IIIA
Or the Perlodic T~ble of ~hich aluminu~ i~ most pref~rred.
Each o~ the metals o~ Type A 18 present in ~t lea~t 1% o~ the total atomic a unt of all the metals Or Type A.
The Type A metals ar~ rrom groups lA, lB, 2A, 2B, 3B, 4A
and 5A from the lanthanlde rare earth metals, or ~rom the actinide rare earth met~ln. me Type A metals ~ill normally have v~lences from one to three. Prererably the Type A matals having valence one are ~rom group8 lA and lB; the Iype A met~ls havlng valence t~o are ~rom group8 2A, 2B, 4A, and the lanthR-nlde rsre esrth metals ~hich ~orm oxide~ o~ the typ~ RE(II)O, and the Type A metals havlng valence three are from group 3B
or rrom the l~nthanlde rare earth metals. Mo~t preferably ~t least two of the ~ype A metal lons dl~fer in ~alence.
A pre~erred class Or compounds hs~ing variable valence metal ions occupylng Bl sltes and h~Ying the perovskite structure ha~e from about 1% to up to 20% Or the B cation site~
occupied by ruthenium or pl~tinum ion~ and the remainder o~
the B catlon sltes occup~ed by ions con~isting e~entially of cobalt ion~, and the A cation sites are occupied by lanthanide 1074~81 ions of atomic number 57 to n and ion~ Or ~t least one m~tal Or groups lA, 2A and 4A Or the periodic table having ionic radil o~ about 0,~ Ang~troms to 1.65 Angstroms and propor-tioned ~o th~t no mnre than 50% Or the cobalt ions are tetravalent and the remaining cobalt ions are trivalent.
Particularly pre~erred are compositions h~ving the formula [Srx~al_x~ CC1_YR~ 3 ~hereln y 18 rrom 0.01 to 0.2 and (l-x) i~ 0.95(1-y) to 0.5(1-y) and compositions having rormuls ~SrXLal_~Cl [Cl yPty~o3 ~herein y iB from 0.01 to 0.1 and (l-x) i8 0.95(1-y) to o.5(1-y).
In other aspects this in~ention comprises ~ny Or the abo~e compounds on a shaped ~upport and afflxed to such a support ~ith a blnder. The preferred embodiment Or the support is alumina shaped in the form Or a hon~ycomb.
THE DRA~INGS
Figure 1 shows the percentage conver~ion obtsined in the catalytic reduction o~ nitrogen oxides (NOX) snd in the o~idation o~ carbon monoxide as a ~unctlon Or exces~ carbon monoxlde and Or excess oxygen in ~ internal combu~tlon exhaust ga8 treated ~ith the catalyst Or Example 2.
Figure 2 sho~s the percentage conver~ion o~ nltrogen oxides and c~rbon monoxide as a function Or time using the cAtaly~t Or Example 2.
DETAILED DESCRIPTION OF ~l~n~ INVENTION
me metal oxlde compounds o~ this lnvention are oxldes Or the general empirical ~ormula AB03 (equ~valent to A2B206 iL~74~
A3B309, etc~) containing subst~ntlally equal number~ of catlons of two di~erent types Or metals, called hereln metal~
of Type A and metals Or ffl e B, and at least two difrerent m~tal~ Or each o~ the t~o types. Thus they can be con~idered oxide~ of the formula ~lA2 ~. Al] [BlB2 .. Bi~o3 ln ~hich the total number of lons, ~l, A2~ ~. Ai, i~ æub~tantially equal to the total number o~ ions, B , B2, .. Bi, and in ~hich there are ~t least t~o dif~erent m~tals Bl and B2 0~ Type B. In the ldeal perov~kite structure such oxide~ contaln cations o~ approprlate relatlve 8ize8 and coordination propertles and ha~e cubic crystalline forms in which the cornars of the unlt cube~ are occupied by the larger Type A cations (each coordinated with t~elve o~ygen atoms), the centers of the cubes are occupled by the smAller Type B catlon~ (each coordinated ~ith 8iX oxy~en atom~), and the ~aces of the cubes are occupied by oxygen stoms. Varlations and distortion~
of thls ~undamental cubic crystal structure are known among material~ commonly consldered to be perovskites or perovskite-like. Di~tortions o~ the cubic crystal structure of perovskite and pero~sklte-l~ke metal o~ide~ include rhombohedral, ortho-rhombic, pseudocubic, tetragonal, and pseudotetragonal modi-fications.
A~ indicated, the compounds of thls invention con-tain at lea~t tNo metals o~ ~gpe A and at lea~t ~o metal~ o~
~ype B. At l~ast one o~ the metal8 of Iype B i8 a metal o~ the platinum group (element~ of the second and third long perloda in ~roup 8 ln the periodic table) and at least one of the metals of ~ype B i8 a Bt metal (not o~ the platinum group).
Thererore the compounds of this in~ention include metal oxides o~ the type tA11 ,~A23 CBI~ e~03 ~7~
havlng perovskite crystal structures in which Al and A2 are eaeh one or more mono-~ di-, or trivalent metal~ having ionic radii between about 0.8 and 1.65 Angstrom~;
B~ iB one or more non-plat~num group metals having ionic radii between About 0.4 and 1~4 Angstroms;
Me i8 one or more of the platlnum metal~ ruthenium, o~mium, rhodlum, lridium, pall~dium, and platinum;
X i8 between about 0.05 and 0,95; and ~ i8 between about 0~01 and 0.20.
The particular T~pe A metals pre~ent in the metal oxide compounds of this invention are le~æ critical than th~ Type B metals, an importAnt property of the Type A
metals b~ing the radli Or their cations. The importance o~
ionic radii ln p~rovskite crystal structures has be~n dls-cuss~d by many authors, e.g. by Krebs in ~Fundamentals Or Inorganic Cryst~l Chemistry~, McGrs~ Hill, ~ondon (1968).
Assuming that the cry~tal structure i8 formed by the packing o~ spherlcal lons, there can be derived the relationship RA + Ro ~ t ~ ( ~ + Ro) in ~hich RA, ~, and Ro are the ionie radli Or the Type A
metal, the Iype B metal, and the o~ygen ions respectlvely and t i~ a tolerance factor. Tetragonal perov~klte crystal atructures are usually obtained in ~imple ternary compounds ~hen t i8 bet~een about 0.9 and 1Ø Dl~torted perov8kite-type structures usually result ~hen t i~ bet~e~n about 0~8 and 0.9. Perov~kite-type structures can be obtained with Nidor departures ~rom thls ldeallzed picture in the more com-plex compounds o~ the pre~ent lnvention, particularly when these compound~ contain small proportions o~ ions havlng radil larger or ~maller than would be acco d~ted Nlth the - ~ .
~ .

tolerance factor t between 0,~ and 1,0, Ionic radii have been tabulated by Shannon and Prewitt Acta. Cryst. B26 10ll6 (1970); B25 925 (1969~.
The metals of Type A can be from the periodic table groups lA, lB, 2A, 2B, 3B, 4A, and 5A, from the lanthanide rare earth metals (atomic number 57 through 71~ and from the actinide rare earth ~etals (atomic number 89 through 104~ .
The metal of Type A in these compounds which have valence one are metals from groups lA and lB. Preferably they are cesium, rubiaium, potasslum, sodium, or silver and more preferably they are potassium or sodium.
Similarly the Type A metals having valence two are from groups 2A, 2B, 4A, and the lanthanide rare earth metal~
~hich form oxides of the type RE(II~0. Preferably they are barium, strontlum, calcium, or lead and more preferably they are strontium or barium.
Llkewise the Type A metals having valence three are from group 3B, 5A, and the lanthanide and actinlde rare earth metals. Preferably they are lanthanum or a mixture of the lanthanlde rare earth metals (e.g. a mlxture contalning about one-half cerlum, one-third lanthanum, one-sixth neodymium, and smaller amounts of the remaining metals of atomic number 58 through 71 or a slmllar mixture from which a ma~or part of the cerium has been removed), which mixture 18 deslgnated hereln by the ~ymbol _ The B' metals which constltute about 80% to ~9~ of the metals of Type B in the invention compounds are ~rom groups lA, lB, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6B, 7B, and 8 or from the lanthanide or actinide rare earth metals, The B' metals having valence one are from groups lA
and lB, Preferably they are sodiu~ sllver, or copper.

_g_ ,~

., .

The Bl metals having valence two are from groups lB, 2A, 2BJ 3B, 6B~ 7B and 8. Preferably the~ are ~agne~ium, calcium, ~trontlum, chromium, manga~ese, iron, cobalt, nickel or copper.
me B' metal~ having vslence three are ~rom groups 3A, 3B, 4B, 5B, 6B, 7B, and 8 and khe lanthanide and actinide rar~ earth metals. Preferably they are lanth~num, a lanthanide rare earth metal, aluminum, chromium, manganese, iron, ~obalt, or nlckel.
The B' metsl~ havin~ valence ~our are from groups 4A, 4B, 5B, 6B, 7B and 8. Pre~erably they are titanlum, tin, vanadium, chromium, molybdenum, mangane~e, iron, cobalt, nickel, or rhenlum.
The B' metal~ having valence flve are from group8 5A, 5B, and 7B. Prefer~bly they are antimony, niobium, tantalum~ vanadium, or rhenium.
The Bt metals having valence 8i~ and ~even are pre~erably tungæten, molybdenum, or rhenium.
Bet~een about 1% and about 20% of the cations of metals of Type B in the inventlon compounds are the lon~ Or platlnum metal Ruthenium, osmium, rhodium, and iridium are capable of occupying all o~ the Iype B cation sites in perovskite cry~tal structures, but little additional beneflt is achieved ~h~n re thsn about 20% of the sites are occupied by these metal~. Palladium and platinum ions are larger than rutheniu~, osmium, rhodium, and iridium ions and generally not more than about 10% of the Type B ~lte~ of crystalline o~ides of the AB03 type can be occup~ed by the lons o~ the~e metal~ ~lth retention of a perov3kite structure. Palladium i~
typically divalent; rhodlum i~ typicall~ tri~alent; ruthenium, .

lridlum, and platinum are typically tetravalent; and osmium can have ~ valence of four, ~ive, ~;ix or seven in these com-pound~. Mixtures Or the platinum metals obtained by the partial refining Or their ores are use~ul in these compound~.
me metal oxide~ of this invention containing ruthenium are partlcularly use~ul as catalysts for the reduc-tion of nitrogen oxides. They generally catalyze the reduction Or these oxides to innocuou~ compounds (e.g. nitrogen) instead o~ to ammonia. Such oxides containing ruthenium arer in general, more stable th~n similar compounds containing 08mium~
po~sibly because of the lower volatillty of ruthenium oxides, and are also preferred because of the generally greater tosicity o~ osmium compound~. Metal oxides containing platinum and palladium are particularly useful as catalysts for the complete o~id~tion of carbon compounds to carbon dloxide.
me metals of Type A and of Type B indlcated to be preferred in the various valences one to seven are pre~erred because of on~ or more Or the following reasons:
(1) their ionic size, with correspondingly lncreased ease Or rormatlon and greater stability o~ perovskite crystal ~tructures;
(2) thelr capability Or exi~ting in perovskite crystal structures in whlch they are in more than one valence;

(3) their generally high catalytic activlty and/or selectivity in metal oxide compounds; or

(4) thelr greater abund~nce and corre~pondlng generally lo~r co~t.
(5~ their stability in perovskite ~tructures.
Certaln compounds o~ t~L~ in~ention contain B~
metals having a single rixed valence, Such compound~

~4~
have a maJor proportion (e.g. at least 50% and preferably 75~ or more) o~ Bl sites occupled b~ metal ion~ which are known in perovskite crystal ~tructures primarlly or only in one valence in ~ddition to the ions of the platinum metal.
The B' metal ions of this group are:
valence 1: llthium, sodium, silver;
valence 2: magne~ium, calcium, ~trontium, barium, ~inc, cadmium;
valence 3: aluminum, gallium, lndium, thallium, lanthanum, yttxium and neodynium;
valence 4: zirconium, hafnium, thorium, germanium, tin;
valence 5: antlmony, tantalum;
valence 6: tungsten.
Preferably the Bl metals o~ thls clasæ are sodium, magnesium, calcium, ~trontium, aluminum, tin or antimony. mese rela-tlvely abundant metals can be present in the compounds of thi~
embodiment in ma~or proportions with relatively sm~ll reduc-tlons ln the catalytic sctivity contributed to these compound~
by other le~ readily ~ailable metal~ and therefore represent relati~ely ine~pensive diluents in such compounds. More preferably, the compounds contain aluminum as the m~or B~
metal. Aluminum iB not only an inexpensive diluent but 8180 i~part~ to perovskite cry~tal structures a high degree of thermal stsbility and durability in catslytic appllcation~.
Another class o~ compound~ contain a maJor propor-tion (e.g. at lea~t 50% and pre~erably more than 75%) Or B~
sites occupied by met~l ions which are kno~n in a ~irst Yalence in one pcrov~kite compound and in a second Yslence in a second pero~skite compound. Such B' metal~ kno~n in perovskite crystal structure~ in two valences dir~ering in increments of one or two - ~, , ~ . .' ' .

~074 [)~3~

valence units Bra valences l and 2: copper;
valences 2 and 3: scandium, ~lamarlum, ytterbium;
~alence~ 2 and 4: lead;
valences 2, 3, and 4: chroml~, manganese, iron, cobalt, nlckel, and cerium;
valence~ 3 and 4: titanlum, pra~eo~ymlum;
valences 3, 4, and 5: vanadium;
valences 3 and 5: bismuth niobium valences 4 and 6: molybdenum;
valences ~J 5, and 6: rhenium and uranium.
The compounds o~ thl~ class contain one and pre~erably two or more 3uch vari~ble~valence B' metals, particularly those non-platlnum metal tran8ition metal~ whlch have atomlc number~
between 22 and 29 inclusive (tltanium, vanadium, chromium, mangane~e, iron, cobalt, nickel and copper. Most pre~erred are lron, cobalt and nickel. The~e metals are relatively av~ilable and compounds contain~ng them are more generally actlve catalysts, possibly because these metals sre capable Or exi~ting ln perovskite cry~tal structures in two or three valences di~rerlng by one valence unit increments.
In particular, the compounds of this cla~s wherein the variable valence B~ element i~ present in t~o valences con~t~tute an important a3pect Or this invention. Such metal o~ides have lncreased activity 88 catalysts over similar compounds ln ~hich each of the componentmetals i8 present ln only a single valence, pos~lbl~ because o~ the enhanced electron mobllity through thelr crystal ~tructure~ resulting ~rom the pre~ence of a variable-valence metal, when the B' sites are occupied by at about 5~ of a variable-valence metal in ~ ~irst valence and at least 5% Or the Bt slte nnd occupied ~7~

by the same metal in a second valence, The valence~ will u~ually di~rer by one unit but wil:l differ by two units with ~ome metals (e.g., lead and niobiu~).
The proportion Or the t~ valences o~ any variAble-valence metal can be determined by the other metals in the perovskite, their valence~, thelr relatlve amounts, and their total amount relatlve to the amount o~ oxygen in the compound a~ descxibed herein below. Thu~ the compositlon rcao~2Lao~8~ [CovgRuo~1]o3 can be ~ormulated [Ca(II)O ~a(III)O~ rCo(III)O,gCo(IV)O,lRU(IV)O,lJ03 ~ith cobalt present in valences three and four 80 that the total ~alence charge of the metal~ equals the total valence charge o~ the oxygen atoms. Other examples ~nclude ~Sr(II)O 2RE(III)0~8]~co(III)o.8co(Iv)o.lRu(Iv)o~lJo3 [Sr(II)o ~ (III)o~g~tco(III)o~8co(lv)o~lpt(Iv)~ 3 ~K(I)O.2Sr(II)O~2La(III)O.6~ CC(III)O,4C(rV)O,4RU(~V)O,2~03 ~Ba(II)0.5La(III)o~s] [Li(I)o~ )o.4~(IV)o~4s(vI)o~l~o3 In those compo~itions ~hich contain t~o or more metal3 which may be present in t~o valences (e.g., manganese and osmlum the last composition above), the assignment of the relative amounts o~ each metal to a given Yalence claæs can be made ln accordance ~ith the discussion~ hereinabo~e o~ the metals ~hich ~re capable o~ existing in perovskite and perovsklte-like crystal structures ln more thsn one vAlence and of the import~nce o~ ionic radii in the ~ormation and distortlon of perov8kite structures.
Among the particularly preferred compounds withln thi~ subgroup are compounds ha~ing the formNla ~Sr ~ l~x~tC l-y~ y~ 3 ~hereln Me i8 platinum or ruthenium, y i8 about 0.01 to 0.2, ~7~

~hen Me i8 ruthenium and about 0.01 to 0.1 when Me i8 platinum, and x i~ selected to gi~e 5% to 50% o~ the cobalt ions in the tetravalent ætate. From the requirement o~
electrical neutrality it follows that (l-x~ )(l-r) ~hen ~ 1B the rraction Or the cobalt lons in the tetra~alent ~tate, 80 that with the above limitatlons (l-x) = 0.95(1-y) to 0.5(1-y), In the above, the stoichiometric requisite Or metals and oxygen are met. However, this invention should be understood to lnclude compounds containing defect structure~
with an exce~ or A deficlency of metal ions Or up to 25 atomic percent Or the requiRite for the ideal AB03 perov~klte crys~al ~tructure, Compounds in which metals are ln particulsr valences ma~, however, form st lower temperatures, be re ~ctive cata-lyst~, or be more ~tsble as catal~ts ln ~ome processe~. For example, there are indications that perovskite~ containing the tran~ition metals ti~anium through copper form at lower temperatures with a lsrger ~raction Or titanium in vslence rour than ln valance three, Nith more nearly e~ual fractlon~
o~ chromium, manganese, iron and cobalt ln valence~ four and three, with a larger ~raction of nlckel in valence three than in valence two, and with a larger fraction Or copper in valence tw~ than in valence one. Vanadium is commonly ~ound in perovskltes in ~alence five.
Other compounds within the scope o~ this invention include o~ 3SrO. 3Ndo, ~} tCUo, ~ T~o 880 l~ o3 ~7~3~

[ 0.025 (II)O~O5RE(III)O,925J [Nit) 9PtO 1]3 .2Bao,2Lao,6~ ~cUo 2Tio 6Ruo 2103 ~RbO. 05SrO, 10LaO~ 85J ~FeO~ 8RUO 2]3 [ -5 aO.2RE(III)O.75] ~CO 8RUO 1~b0 1]3 ~KO 1CaO 2RE(III~O~7] tC0.3~0,4NbO,20SO,1] 3 [K 1SrO 2~ I)0,7~ [PtO,05TiO.7VO.25J 3 ERb0 4C~O 6] ~Pt0. 1Nb0~ 8W~ 1JO3 ~RbO 9BaO.1~ ~tO.1M 0.9 3 ~K0 8BaO- 2~ ~RU0. 2VO. 8~ 3 ~Rb0 7PbO 31 ~Ce0. 2M0, 7PtO. 11 3 rKO.95SrO,O5J ~PdO 05NbO 95~3 ~KO, 25S~O, 75J ~TiO. 65MO. 25RU0. 1]3 ~C~o. 2I'aO. 8] E~o. ~P~o . lTio . 3~ o3 ~C80 lLaO 7Nd0~2J [C0~4cro~4Iro~lp~o.l]o3 ~NaO o5RE( III) 0. 95~ tCuo. lCrO. 2Ni0. 2FeO. 3RU 2] 3 ~CBO 4NdO.6] [C0.3~0.2PtO.2 0-3~ 3 ~;rO 5Bao. 5~ ~Nio. 45PtO. 1VO. 45~ 3 rKO sLaO, 5J ~Tio. 8RU0. 2]3 ~aO, 5LaO, 5~ ~ TiO. 95PtO 05~ 3 20 ~Rbo 5Lao.5~ ~Mo~9pto.l~ 3 ~Rbo 5Ndo.~J ~Tio.g5Pdo.o5~ 3 tC80. 5NdO. 5~ O,9PdO. 033PtO. 033~UO, 033~ 3 EPbo 2SrO. 8~ ~CuO, 2Rh0. 2Nb0. 6~ 3 rBaO. gPbo~ lJ ~Tio. 8RUO. 2]3 CSrO. 6CaO, 4~ tVo. gPto. 1~ 3 ~SrO.9Pbo~ TiO095Iro. o5Jo3 CcaO~ 5BaO. 5~ ~Tlo. gPto~ 1~ 3 rBao~ 3Ndo . 7~ ~0. 4CrO~ 4Ruo. lNbo. 1~ 3 ~ .
~SrO 2La0. 8~ ~CoO. gIrO. 1] 3 30 [Pbo lLaO ~ [CuO. lCrO . 7RUo, 2~ 3 74~

~CaO 3LaO 7~ ~Cdo, lFeO. 5Pto, lT o~ 3~ 3 r~bo~ 5LaO, 5J ~Mno.9Iro~l~o3 ~Bal/2Lal/2] ~Mnl/2Til/3RUl/6] 3 rl/2Lal/2J ~ /2T 1/3P 1/6J 3 tcal/2Yl/2~ /3Rhl/6Til/2] 3 2/3Lal/3~ ~Fel/3Til/3Zrl/6Rul/6~ 3 ~pbl/3srl/3Lal/3~ 3Til/2ptl/6~ o3 EBaO lREo 9~ ~Tio~gPto~lJ 3 ~BaO lLao. 9~ [Tio. gPto, 1~ 3 ~ o~lLaO~g~ tcuo~lNio.4coo 480 1]3 ~SrO 2LaO, 8; 1 I?~o . 8IrO. 2 ~ 3 CBaO.4LaO,6] ~eo.6IrO.1] 3 [SrO 2I~aO, 8] tcoo . 8RUO. 2~ 3 ~SrO lL~o.~J ~io.gPto.l]3 tsro 2I~aO ~ tcoo gPdo 1]3 ~SrO 3I~Io,7~ ~Feo.9Ruo~l] 3 tsro ~0,8~rC00.9~0.1]03 ~BaO 4La0~63 tCoo~9pto.l]o3 ~srO 4Lao, 6J tcoo~ gPto. 1~3 tLao.6Ndo,4] ~Cuo~o5Feo gPto 05~3 ~L~3~4Cel/4] ~e7/8RUl/8] 3 [~1/2Gdl/2~ EP~1/2Cl/3Rhl/6~3 [Kl/3Bal/3Lal/3~ [A11/3Til/6RUl/6Nbl/3~ o3 bo~2Bao~2Lao~6~Ago~lc~o 4Tio 3Nbo 180 1~
~Rbo l~aO lNdo, 8~ tCuo~ 2Coo~ 3zro~ 4RUo, l~ o3 tc80 2BaO 2La0.~ tCu0~2Tio~6Ruo~2~ 3 [Ko~ 025Pb, o5Ndo~ 925] CA10 gRUo 133 t 0, 3C80. 7~ ~rO. 5Moo, 480 1~ 3 [Rbl/4K3/4~ tsb5/6osl/6]o3 3 [Rbo 2BaO 8]tLio lcuo~lcro.3Ruo.o5Iro~o5~,qoo~2 ~o~ 3 tCso 3Ndo 7~ [NaO, lFeO, 4Alo, lIrO~ 2WC). 2~ 3 CRbo lLaO gJ ~M~;o~ 2N~o, 3ZnO. 2WO. lReO. 1 0.1] 3 ~KO 5LaO~ 5~ ~SnO, 8RUO. 2] 3 ~CSO 4NdO 6~ tC0~3~0~2P 0.2 0.3 3 ~1/2La1/2~ [~r1/2Ta1/30 S1/6 ~ 03 rBaO 9SrO 1] ~AgO~ 1TiO, 880.1~ 3 CSr1/2B~1/2] ~Na1/2Re1/3OS1/63 3 ~PbO 2B~O 8~ CI'iO 1CrO. 4COO. 4WO, 050SO, 05] 3 CBa1/2Pb1/2] [Na1j4Rh1/4W1/2~3 tB~.O, 9CdO . 1J CLiO . 1NiO, 3CrO ~ 2C0, 3WO, 05 ~0 . 05~ 3 tCaO, 1BaO, 9~ tAgO. 1CUO, 1~0. 05CrO. 2PtO. 1VO. 05NbO, 2OSO~ 1ReO. 1~ 3 CPbO 6SrO 4~ 6Pd1/6Ti1/3W1/3J 3 CBa1/2Sr1/2~ tA11/2M1/381/6 ] 3 Ccal/2Bal/2] [Mgl/2Wl/3 Bl/6~ 3 ~SrO 5BE~o. 5J tzrO. gIro. 1~3 0.1 0,2LaO,7~ O,2MhO 4Alo lTio lWo lQ50 1~
tCaO 3I,aO 7] tcdo~ lFeO, sPto~ lTiO. 3] 3 CBaO lLaO,g~ tFeo.7Rho.2ZrO.1~o3 [SrO 2LA0.8~ ~ho~ o~2Ruo~l~o3 tsro, 2LaO, 8~ G~lo. 8Ruo 2 ~3 [SrO, 2La0. 8~ ~lo, 7~Rho, 1~0., 2'~3 [BAO 1REO,9~ CTiO~9PtO~1~ 3 tSro~ o6Lao. 94 ~ ~Alo. 80Co. l6RUo. 0~ 3 CRE( ~ [LiO, 2NaO, lAgo. lCrO, lsMho~ 15Pt0. lNbO. lReO. 1 ~3 C 0.4NdO,6~CCUO~1CrO~2COO 2N1 2Fe 2RU 1~03 t 0,5NdO,5~ ~LiO.3~0,3TiO 3OSO 1~3 CF~1 ~ 0.85 0.15] 3 [RE] [CUO, 1COO, ~UO~ 1~3 CRE~ E~O,gIrO 1~3 ~9'7~

~RE~Cuo~lAlo.8Iro.l] 3 [Lal/2 1~2~ ~ 1/2 1/3 lJ6~ 3 tRE][Feo~gcro~lRho~l]o3 ~RE][Mgo~5Tio~4sIro~o5} 3 ~Lal/2Ndl/2~Mgl/2Til/3RUl/6~ 3 ~RE(III)] [Cuo~sTio.4pto~l~ 3 ~RE(III~ ~Cdo~Pdo~lTio~5~ 3 [La3/4Cel/4]~Fe7/8~Ul/8~ 3 Compound Prep~ration -The compounds of this in~ention can be prepared by heating mixtures of metal oxides, h~droxldes, metals and/or metal salts ~or suff~cient times at temperatures ~hlch permit ; spontaneou~ formation of the compounds. The mixture o~
materials which are heated are preferably finely ~ubdivided and intimately mixed before heating and are thoroughly ground and mixed by any conventional techniques several times during the heating period, ~ince the compounds are in many instances formed by atomic diffusion, without melting of any of the st~rting or potential intermediate materials, and are subJect 2~ to coating Or unreacted particles by reaction products. The heating times and temperatures required ~or the ~ormation of significant amounts o~ these catalytic compounds depend upon the particular compositions being formed, the required times usually being shorter at higher temperatures. Temperatures above about 800C. are usually suitable for the ~ormation o~
the~e compounds but temperatures aboYe about 900C. are usually ; preferred with firing times of hours to d4ys with occasional intermediate grindlng and mixing and temperatures of 1,000 to 1,500C. may be used.
In forming the compounds Or this invent~on, stoichiometric mixtures of starting materials are pre~erably heated in air or other oxygen-containing ga~ mixture.

The startlng material~ w3ed in preparing the com-pounds Or this invention by anhydrous processes can be any 8alt8 which are converted to oxide~ by prolonged heatlng in oxidizing stmospheres at the temperatures at which these com-positlon~ are ~ormed. For example, they can be carbonates, salts Or carboxylic acids (e.g. J a~etates, oxalates, tartrates, etc ), salts of the acids of sulfur (e.g., 8ul-fide~, sulfltes, sulfAte~, ets.), halogen acid salts ~hich are converted to oxldes ~lthout volatilizatlon te.g., ruthenium chloride, strontlum chlorate, barium perchlorate), ~alt~ of the acids of nitrogen (e.g., nitrates, nltrltes, etc. 3 . Preferably they are carbonates, nitrates or sulfate~.
The presence of 8mall amounts of the salt~ of other such acids in a mixture whlch i~ predominately oxldes or car-bonates lg u~ually not significantly deleteriou~ since such salts are converted into oxides during heatlng to prepare these catalytlc compositlons.
me compounds of this inventlon are presumed to ~unction as catalyst~ pri~arlly at their ~ur~aces, 80 com-position~ with signlficant sur~ace areas are preferred.me surface areas o~ compounds prepared by heating mixtures of material~ can be increased by grlnding and other conven-tional method~. Catalytically active compounds with surraee areas between about 0.1 and 10 quare meters per gram (determlned by the well-kno~n Brunauer-Emmett-Teller ~ethod) can be obtained. Compounds ~ith ~urface areas greater than about one square meter per gram are pre~erred. The surface area of these compounds remalns relatively unchanged during use by virtue Or their compositional and structural stability at high temperature~.

~ ~ 7 ~

Catalyst Forms The compounds described herein can be used as cata-lysts in the form of free-flowing p~wders, for instance in ~luid-bed reaction systems, or ln the form of shaped struc-tures providing efficient contact between the catalyst and the reactant ga~e~, Such catalyst structures can contain minor (e.g,, less than about 50~ or major (e~g., more than about 50% to about 98~) amounts of catalytically inert material~.
The~e inert materials can be either porous or solid, with the 1~ catalytic compounds primarily on the surface~ thereof or more or le~s uniformly dispersed throughout. For example, the powdered compounds can be formed into porous catalyst pellets in which they are dispersed throughout by conventlonal tech-niques employing pellet presses, rolling mixers, extruders, etc. Preferably such pellets contain suitable dispersants, lubricants, and/or binders.
One p~rticularly useful dispersant-binder for use t~ in forming extr,llded pellet catalyst structures containing the catalyst compositions described herein is a high-purity alpha alumina monohydrate sold by the Continental Oil Co. as "Dispal"*.
This material is a white, free-flowing powder of small partlcle slze formed o~ very fine ultimate crystallites having a sur-face area of about 200 square meters per gram and a bulk den-sity o~ 45 to 50 pound~ per cubic foot. It forms th~xotroplc dispersions at concentration~ of about 3% to 30~ in water con-taining about 4% to 6~ commercial concentrated (37~ HCL~ hydro-chloric acid based on the weight of alumina, which dispersions become thicker upon standing. Thick di~persions containing about 20 to 30 parts of the alumina monohydrate and about 100 to 150 parts of acldified water per 100 parts of a catalytic composition having a surface area of about two ~uare meter~

* denotes trade mark ~A

~, ~

~07~81 per gram can be extruded through ~mall orifice~ to obtain structures which retain their rorm ~hen ~et and have significant strength when dried Or gross water and heated at about 500C.
to about 900C. to remove at least a part of the water present in the alumina monohydrate.
The compounds of thi~ in~ention are preferably employed as catalysts in the rorm of coatings on suitable re~ractory supports. Such ~upport~ can be in any convenient ~hape, including powders~ granules, spheres, rings, tablets~
pill~, bar~, tubes, extruded shapes, rolls, spirals, screens, beads, coil~, and the more elaborate shape~ (e.g., corrugated and ~lat sheets, honeycombs, etc.) prepared by a variety of methods and recently available to the art.
Suitable support~ can be composed solely or primarily of sillca, of ceramic compositions having softening or melting temperatures above the temperatures involved in ~orming or coating these catalytic compositions on such supports, o~
natural silicious materials ~uch as dlatomaceow earths and pumice, as well as of alundum, gamma alumina, silicon carbide, titania, ~irconia, and other such reractory materials.
A particularly use~ul refractory support $~ an alumina ceramic described by Tal~ma in U.S. Patents 3,255~027;
2,338,995; and 3,397,154. Such materials can be made by coatlng an aluminum foll fabricated into a ~haped structure having the deslred final configuration with a fluxing agent and rirlng to convert the ~lumlnum into substantially pure alpha alumina. Sultable flu~ing agents include alkali and alkaline earth metal oxide~ and compounds which yield such oxides on firing (e.g, sodium ~ilicate) which serve to pre-~ent inhlbition Or oxidatlon of the aluminum due to oxide scum formation on the surface of the alumlnum. One suchalumina contains, ror example, small amounts of magnesium aluminate and aluminum silicate. A~ discloæed in the Talsma patent~, honeycomb structures can be made by placlng flux-coated corrugate sheets o~ aluminum together node-to-node and flring. Similar ~tructure~ can be obtained by applying a composition containing aluminum powder, a binder, a fluxing agent, and a liquid carrier to a corrugated paper honeycomb structure and firing in an oxidizing atmosphere to burn out the paper structure and oxidize the aluminum to alumina.
Honeycomb structure~ o~ such alumins compositions can be pur-chased ~rom the Indu~trlal Chemicals Department, E.I. du Pont de Nemour~ & Company, under the trade mark "Torvex". The pre-rerred structures have nominal cell slzes 1/16 to 1/4 inch.
The compounds can be applied to suitable ~upports in several ways. For e~ample, they can be ~ormed upon ~upports which are su~iciently high melt~ng and nonreactive by soaking the support structure in a solution Or a ~uitable mixture of salts, dry~ng, and firlng the impregnated support to a temperature and ~or a time sufficlent to form the ca~alytic structure. Alternately, the compounds can be pre~ormed and applied to the support structure in a 81urry which can optionally contaln diluent materlals which can also be cata-lytic materials. A particularly userul dispersant-binder for u~e in such slurry-coating processe~ iB the "Dlspal" alpha alumina monohydrate described here~nabove as a disper~ant-binder useful in making extruded catalyst structures. Iypi-cally, acidi~ied dispersions containing about 4% to 10% alpha alumina hydrate and a comparable amount of the ground cata-30 lytic composition are prepared, piece6 o~ the support material : . ' :, ' ~07~08~.

are coated wlth the dispersion, the coated pieces are dried~
and the dried coated pieces are heated to a temperature and for a time (e.g., ror 2 to 24 hour~ at 500C. to 900C.) to remove at lea~t a portion of the water ~rom the alpha alumina monohydrate. Other support material~ and techniques for applying catalytic materials to supports, useful and errective Nith the compounds o~ thi~ lnvention, are described by So~ard~ and Stiles in U.S. Patent 3,518,206 and by Aarons in U.S. Patent 3,554,929.
Advanta~es o~ Compounds as Catalysts The metal oxides o~ the present lnvention are stAble and durable at high temperatures and have been shown to cata-lyze the oxidatlon o~ hydrocarbons and carbon monoxide and also the reaction bet~een nitrogen oxide (NOx) and carbon monoxide to give nltrogen and carbon dioxide. They are not poisoned b~
the lead compounds present in the exhaust of internal combus-tion engines operated on leaded gasoline. Accordlng}y, an important use of the cataly~ts of this invention is the removal of noxlou~ components from the exhaust o~ internal combustion englne~. For this purpose the catalyst~ are preferably supported on shaped alumlna supports, slthough other supports inert to the exhaust gas at the operating temperature may be used.
A~ ~orm~d by heRting and grinding, the compounds of the present invention are obtained in the form of a crystal-line powder. Particularly e~ecti~e and durable catalysts for use in treating the exhaust gases o~ internal combustion englnes operatlng with leaded ~uels are obtained when this powder is supported on an alumlna ~upport, pref~rably the honeycomb-8tructured alumina supports sold under the trade name ~Torvex" described hereinabo~e. The catalyst powder ~ )7~8:i should be applied to the surface, together with a binder to a~fix the same to the support, in an amount sufficient to coat the entire surface, usually in an amount o~ ~rom 2 to 25~ by weight of the support.
The catalytic compounds of the present invention may be employed to catalyze other reactions similar to the reactions occurring in the purificatlon of internal combus-tion engine exhausts. For such applicati~ns, where lead compounds are absent, a wider variety of support materials may be employed such as pellets or other shaped structures of mullite, cordierite and silica.
This invention is further illustrated by the following specific examples which should not, however, be construed as fully delineating the scope of the discovery.
EXAMP~E 1 Preparation of Catalytic Com~osition A metal oxide of the nominal composition [srO 2LaO ~ ~0O 8Ruo ~o3 wa~ prepared by mixing 10.96 grams of lanthanum oxide (La203), 2.48 grams of strontium carbonate (SrC03), 8.oo grams of cobalt carbonate ~CoC03~, and 2.24 grams ruthenium oxide (Ru02~, grinding and mixing until homogeneous, and heating the mixture in air in a platinum boat inside a "Vycor"* brand silica tube closed with glas~ wool plugs at 950-1000C. for about 4 days during which the mixture was occasionally reground and remixed, There was no significant evidence of volatilization of ruthenium oxide or of its con-densation in the cooler portions of the tube or in the glass wool plugs in the ends of the tube during the heating of the mixture. The resulting composition was ground and passed through a 325-mesh Tyler standard sieve screen.

* denotes trade mark .. . -~ i . . .

1~7~

Application of Catal~tic Composition to a Support One gram of "Dispal" M alumina di~persant and binder was mlxed with 17 milliliters o~ water containing three drop~
of commercial concentrated hydrochloric acid. To thi~ mix-ture was added 7.5 gram~ of the catalytic composition [SrO~2Lao~8~coo.8Ruo.2]o3 described above to obtain a stable thixotropic slurry. A cylinder of alumina ceramic hone~comb with straight-throu~h cells sold under the trade name "Torvex"
was ~oaked ln water. ThiB cyllnder weighed 5.77 grams, wa~
about 2.5 centimeters in diameter and thickne~ and nominally had a cell size of 1~16 inch, wall thickne~ of 0.018 inch, open area Or 50%, 253 hexagonal holes per squAre inch, and a nominal geometric surface area of 462 square ~eet per cubic ~oot. me water-soaked cylinder ~as dipped into the slurry of the catalytlc compo~ition, the gross excess Or slurry was removed by blowing the cylinder with air, the cylinder was dried, and the cylinder coAted with the catalytic compo~ltion and blnder Na~ heated ~or about 30 minutes in a mu~rle furnace at about 700C The cooled support was again dipped into the ~lurry, blown free of gross slurry, and dried and was then heatod for about two hours in the muffle furnace at about 650C. The support wlth adherent catalytic compoæltion and binder weighed 7.74 grams, or 25.5% more than the dry uncoated support. It contained about 0.0106 gram o~ the catalyt~c composition and blnder per æquare centimeter of geom~tric 8ur-~ace.
Catalytic ~ctivity in the Reduction o~
Nitric O~ide by Carbon Monoxide me "Torvex" ceramlc honeycomb cylinder coated with 0.2 0,8 ~ ~CoO. ~u0.2 703 and binder was in~talled in a ~L~7~

~tainles~ steel ~hamber with a nom~nal ~nternal diameter Or 2.5 centimeters, height o~ 2.5 centimeters, and volume of 12.3 cubic centimeters. Nitrogen containing about 2000 parts per million of nitric oxide and about 10,000 parts per million Or carbon monoxide was passed through the chamber at a nominal hourly space ~elocity o~ about 40,000 hr. 1 and pressure o~ 1 pound per ~quare inch gage while the feed gas and the catalyst chamber were heated in a programmed manner 80 that the temperature Or the ga~ entering the cataly~t chamber increased ~rom about 60C to about 600C 0~8r about 90 mlnutes. Samples of the inlet and exit gaæes were ob-tained periodically. me nitric oxide ~n these samples wa~
oxidized to nitrogen dio~ide and the re~ulting gas mixture was analyzed by a modirication of the colorimetric proced-: ure described by B.E. Saltzman in "Analytical Chemistry", Volume 26, pages 1949-1955 (1954). The percent reduction in the nitric oxlde concentration o~ the gas upon pa~sing through the cata}y~t chamber was ~ound to be nil at a catalyst chamber inlet temperature or 200C, 14.3% at 300C, 97.1% at 400C, 98.6% at 500C, and 98.6% at 600C. me catalyst temperature wa~ about 660C with the gas entering the cata-ly~t chamber at 600C. From a ~mooth cur~e through a plot Or th~se re~ults it WaB estlmated that the converæion Or nitric oxide wa~ 25% at about 315C, 50% at about 340C, and 90% at about 390C and that the "light-off" temperature ~the inter-cept Nith the temperature axis o~ an extrapolation of the portion of the curve in which the degree of conversion chang~d rapidly with temperature) was abou~ 280C. The "light-o~f~ temperature and the temperatures of 25%, 50%, ~7~08~
and 9090~ conversion a:Pter heating the catalyst-coated honey-comb cylinder at about 900C for 116 hours and for 216 hours are given in Table I along wlth similar data from evaluations of the catalytic activity of the compositions described in Examples 2 through 9.

Catalytic Activity in the Oxidation of Carbon MonQxide .
The catalytic activity of the above-described "Torvex" cylinder coated with [SrO 2La0 ~ rCO 8Ruo ~o3 10 in the oxidation of carbon monoxide wa9 determined in a similar apparatus and by a similar procedure. Nitrogen containing about 10 000 parts per million of carbon monoxide and 10 000 parts per million of oxygen wa~ passed through the catalyst chamber and the entering and exitlng gas mix-tures were analyzed chromatographically using a column con-taining granules of "Linde "* 13X molecular sieve The con-version of carbon monoxide was found to be 6.6~ with a catalyst chamber inlet temperature of 140C3 7.1% at 200C,

5.4~¢ at 245C, and 100% at 275C and at 305C. The tem-20 perature of the catalyst was 330C with a catalyst chamberinlet temperature of 275C. From a smooth curve through a plot of these result~ it was estimated that the conversion of carbon monoxide was 25% at about 250C, 50~¢ at about 260C, and 90,¢ at about 270C and that the "light-off" tem-perature was about 245C. The "light-off" temperatures and the temperatures of 25%, 50%, and 90% eonver~ion after heat-ing the catalyst-co~ted honeycomb cylinder at about 900C
for 116 hours and for 216 hours are given in Table I along with similar data from evaluations of the catalytic sctivity 30 of other compositions described in Examples 2 through 10.

* denotes trade mark -2~--7~
Catalytic Activity in the Oxidation of pro~ane The above-described '~orvex" ceramic honeycomb cylin-C 0.2Lao 8~ @oO 8Ruo ~ 03 and binder was heated in a muffle furnace at about 900C for 116 hours, The catalytic activity of the cylinder in the oxidation of propane was then determined in a ~imilar apparatus and by a similar procedure, Ni-trogen containing about 1300 parts per million of propane and 880 parts per million of oxygen was passed through the catalyst chamber and the entering and exiting gases were analyzed chromatographlcally using a column containing 80-100 mesh "Poropak~* Q. The conversion of propane was found to be 7,9~ with a catalyst chamber inlet temperature of 190C, 8,9~ at 285C, 29.9~ at 385C, 78.0% at 505C, and 94.6% at ~00C. The catalyst tempera-ture was 605C with a catalyQt chamber inlet temperature of 505C. From a smooth plot of these results it was estimated that propane converslon was 25% at about 250C, 50% at about 415C, 75% at about 490C and 90% at about 565C

and that the "ligh~-off" temperature was about 290C. The "light-off" temperature and the temperatures of 25%, 50~, and 90% conversion after heating the catalyst-coated honey-- comb at about 900C for 216 hours are given in Table I
alone with similar data from evaluations of the catalytic activlty of other compositions de~cribed in Examples 2 through 10, * denotes trade mark A

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Pre~aration o~ Catalytic Composition -A metal oxlde having the nominal composition ~r0.2Lao~8 ~ ~oO.9RUo 1~ 3 was prepared by dissolving 351.8 grams o~ lanthanum nitrate (La(N03)3.5H20~, 44.5 gramæ
Or strontlum nitrate (Sr(N03)2), and 275.5 grams of cobalt nitrate (Co(N03)2.6~20) in about 4 liters of water, adding quickly and with rapid agitation a solution of 402.5 grams o~ potasslum carbonate (K2C03) in about two liters of water~
separating the precipitated mixture of carbonates, drying the separated carbonates overnieht at 120C, adding 14.0 grams Or ruthenium oxide (RU02), mixing thoroughly, heating in a mu~fle furnace at about 1000C ~or 1 hour, grinding and mix-ing thoroughly, and then heating at about 950C ror 4 day~
during which the composition ~as ground and mixed at 3 inter-mediate times. The resulting black composition was ground and passed through a 325-mesh Tyler standard ~ieve screen.
It contained 4.0% ruthenium, determined by X-ray rluorescence spectroscopy and comparable to the 4.22% ruthenium indicated by the ~ormula and included in the preparation.
Another preparation ~howed that an equivalent com-position was obtained when ruthenium oxide was added to a pre-cipitated mixture o~ carbonates be~ore separatlng the mixture from the supernatant liquid.
The X-ray di~fraction pattern o~ the above-describ-ed catalytic composition ~rO.2LaO.8 7 ~oO,gR 0.1 ~ 3 ed the composition to be a single phase having a structure of the perovskite type similar to that of LaCoO3. The precision Or cell dimensions calculated from this pattern ~as reduced by the presence in the pattern of broad and/or weak lines ' .

~0740~

reflecting~ in part, the introduction of small fractions of strontium and ruthenium into LaCoO3. Cry~tal cell dimensions calculated from some of the lines of the X-ray pattern indicat-ed a cell volume of 56.39 cubic Angstroms per formula unit, which value i8 significantly different from the corresponding dimenslons of the known perovskiteæ LaCoO3 (cell volume 55~960), SrO 2LaO 8CoO3 (cell volume 56.13) and SrRuO3 (cell volume 60.45~. me different cell volume reflects the ex-pected enlargement o~ the crystal cell upon introduction Or a small amount of ruthenium into the crystal structure of SrO. 2LaO. 8Co3' Application to a Su~port The above-described catalyst composition 0~2Lao~8~7 ~CoO gRuo 1-73 was applied to pleces of l'Torvexl' alumina ceramic honeycomb substantially as described in Example 1~ using a thick thixotropic slurry containing 53 grams of ~Dispal'l M alumina dlspersant and binder, 3 milliliters of commercial concentrated hydrochloric acid, and 20 grams of the cataly~t compositlon in 453 milliliters of water. The 20 ceramlc honeycomb pieces were of two types: one piece llke that described in Example 1 and 6 pieces each about 5.0 cen-timeters in diameter and 2.5 centimeters thick and weighing about 34 grams, with a nominal cell size of 1/8 lnch, wall thickness of 0,03 inch, open area oP 60%, area per roughly hexagonal hole of 0.01 square inch, and geometric ~ur~ace area of 384 square ~eet per cubic foot. The dried and heated coated pieces weighed about 20% more than the dried untreated pieces. me larger coated pieces contained about 0.0127 gram of the catalyst composition and the smaller piece contained 30 about 0.0107 gram of the catalyst composition per square ., :

~ 074~
centimeter of the geometric surface area.
Catalytic Activity in Reduction of Nitric Oxlde by Carbon Monoxide The catalytic activity of the above-descrlbed smaller cyllnder of "Torvex" alumina ceramic honeycomb coated with the composition CSrO ~LaO 8~ E -9 ~ 3 in the reduction of nitric oxide by carbon monoxide and in the oxidatlon of carbon monoxide was determined substantially as described in EXample 1. The "light-off" temperatures and temperatures of 25%, 50~ and 90% conversion are given in Table I.

Catalytic Activity with Automotive Exhaust Gases The 6 larger pieces of "Torvex" alumina ceramic honeycomb coated wlth ~rO 2LaO,~ ~ 0 9 0 ~ 3 binder, weighing in all 246 grams, were mounted in an insul-ated stainless steel chamber bolted to the exhaust port of a "Kohler"* Model K91 single-cylinder gasoline engine (8.86 cubic inches displacement, nominally 4 hor~epower~ fitted with an electronic spark ignition system and loaded wlth a heavy fan, The engine was operated at 3000 revolutions per minute at an air/fuel ratio of approximately 13.9, using an unleaded premium grade gasoline to which was added 2.0 grams per gallon of lead as "Motor Mix"~etraethyllead antiknock compound con-t~ining the usual amounts of ethylenedichlorlde and ethylene-dibromide scavengers and a commerclal premium grade heavy duty SAE 40 grade lubricating oil containing a typical com-bination of additive~ including phosphoru~, sulfur, etc. The engine was overhauled at intervals of about 300 hours. Under 3 these operating conditions the exhaust gas temperature was 690-750C (typically 720C~, the nominal gas hourly space * denotes trade mark ; ~

.
-~ ~74q~

velocity Or ~xhaust gas through the catalyst chamber w~about 18,000 hr. , ~nd the exhauæt gas contslned about 2.8%
carbon monoxide, 0.1% nitrogen oxides, and 0.9% oxygen. The nitrogen oxide~ were determined as deæcribed in Example 1 and the carbon monoxide and oxygen were determined chromatograph-ically arter condensing most of the water in the exhau~t g~8 in a trap cooled by an ice bath and passing the remaining gas through a small-pore ~llter to remo~e entrained and particul-ate matter.
A~ter each 100 hours Or steady-state operatlon under these conditions, the air/ftuel ratio was increased to obtain in the exhau~t gas sbout 3% excess oxygen, defined as Excess 2 (%~ Mea9Ured 2 (%) - O-5 ~easured C0(%) ~. me engine and catalyst were allowed to come to temperature equilibrium and the conversions o~ nitrogen oxide~ and Or carbon monoxlde were determined. ml~ procedure was rapeated with step~ise reduction of the air/~uel ratlo until the exhaust gas con-tained about 3% exces~ carbon monoxide, defined as Excess C0 (%) ~ Measured C0 (%) - 2 ~easured 2 (%) ~.
The conversions o~ nltrogen oxldes and of carbon monoxlde thu~ determined with di~erent exhaust-ga~ composltions after 100 and 1000 hours of engine operation are shoNn in Figure 1.
Converslons Or nltrogen oxldes and of carbon monoxlde obtained after 100-hour intervals ~rom plots like that of Figure 2 are ~hown ln Table II and in Figure 2. me temperature of the cataly~t Wa8 typicall~ 820C during ~teady-~tate operation.
After 1000 hours the cAtalyst ~eighed 223 grams J representing A net 10B8 from the catalyæt chamber o~ 23 grams. The ga~o-llne con~umed durlng the 1000-hour test contained 468 grams o~
lead. During the test a total o~ 3075 gram~ o~ makeup oll wa~

~7~

added to the engine crankcase.

Prep~ration o Catalyti c Compo8i tion Another metal oxide oomposition having the nominal ~ SrO.2La0.8 ~ ~CoO~gRUo~1~3 wa~ prepared by dis~olv-lng 41.2 grams of lanthanum nitrate (L~(N03)3.5H20), 5.5 gram~
o~ ~trontium nitrate ~Sr(N03)2), 335.3 gram~ of cobalt nitrste (Co(N03)2.6~ 0) and 30.0 grams o~ ruthenium chloride (RuC13.2H20, containing about 41.5~ Ru) in about 4 liters of ~ater, adding 810~1y and with vigorous stirring a solution of 509.1 gram~ Or potassium carbonate (K2C03) in 1700 milliliters of w~ter~ eparating the precipitated mixture of carbonate~, drying At 120C, under reduced pressure, heating for one hour at 1000C, grinding and mixing thoroughly, and heating ~or sn addltlonal 3 dags at 1000C during ~hich the bulk volume of the composition reduced rrom about 1200 milllliters to about 300 mllliliters. me re~ulting black composition wa8 ground and pa~s~d throu~h ~ 325-mesh screen sleve. me X-ray di~rrac-tion spectrum of thls compositlon ~as essentlally identical ~ith that o~ a compo~ition o~ Example 2 and was sub8tantially unchanged by heating ~or an addltional 100 hours at 900C.
Applic~tion of Catalytlc Composition To a Su~port Procedure~ 8imil8r to those of Exsmple 2 were u~ed to apply the above-de~cribed catalytlc composition ~rO 2LaO 8 ~ ~ oO gRuO l ~03 to cylinder~ o~ "Torvex" alumina ceramic honeycomb of the 2 ~lzes described in Example 20 me coated cylinders weighed 15.2 to 18.2% m~re than the dry un~
coated cylinders.
Catalytic Activity o~ Supported _ Com~o~itlon The catalytic acti~ity of the above-de~cribed ~79~C~81 alumina ceramlc honeycomb coated l~th the composition ~SrO 2LaO~8~7 ~oO,gRuO 1 ~3 and blnder in the reduction of nitric oxide by carbon monoxide and in the oxidation of pro-pane were determined sub~tantial~r a~ described in Example 1.
The "light-o~f" temperature and the temperatures Or 25%, 50%
and 90% conversion are glven in Table I.
Catalytic Activity o~ Supported Composition with Automotive E~hau~t GAses The above-described coated alumina ceramic honey-comb cylinders had substantially the same catalytic act~vity a~ the cataly~t of Example 2 in the reduction of nitrogen oxides and in the oxidation o~ carbon noxlde in automotive exhaust gases in a 1000-hour te~t substantially identlcal to that descrlbed in Example 2. Table II includes conversions Or nitrogen oxides and of carbon noxide obtained at 100-hour intervals during this te~t.
Preparatlon of Extruded Cataly~t Composition A thick paste containing 50 grams o~ the above-described cat~lytic composition ~ rO ~ 0 8~7 ~o gRuo 1 ~3 42.5 gram~ o~ ~Dlspal~ alumina dlspersant and binder, 12.5 drop~ o~ commerclal concentrated hydrochloric acid, and 62.5 milliliters o~ water was extruded under pre~sure through a hole nominally 0.125 inch in diameter. The extruded forms ~o ob-talned were dried at 120C under reduced pre~sure, broken into ~egments about 0.25 inch long, and heated ~or 100 hours at about 900C.
Catalytic Activit~ o~ Extruded Catalyst Compo~ition These extrusion product~ containing the catalytic ~ 0.2 0.8 ~ ~CoO gRuo~l ~03 ~nd binder were placed in a cataly~t chamber about 3.0 centimeter~ long and 1.5 centimeters in diameter and their catalytic activity in the reduction of nitric oxide with carbon monoxide, the oxlda-` 1(~7~a~8~

tion of carbon monoxide, and the oxidation Or propane was determined as described in Examplle 1 at an hourly gas space velocity o~ about 50,000 hr. 1 before and a~ter heatlng ~or an additional 220 hours at about 900C. me "light-ofr" tem-peratures and the temperatures of 25%, 50% and 90% conversion are given in Table I.

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~ .¢ CU
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~ s~

co~ o o o o o o o oo o o h 00 O O O O O O OO O O
:5 0 ~I C~ ) ~ O

~74~8~

Preparation o~ Catalyt;ic Composition A metal oxide having the nominal compositlon ~SrO 21aO~ CoO,gRuO~l_703 was prepared by dissolving 50 gram~ of lanthanum nitrate (La(N03)3.6H20), 6.11 eramS of strontium nitrate (Sr(N03)2), 38.0 grams of cobalt nitrate (Co(N03)2.6H20), and 3.4 grams of ruthenium chloride (RuCl3.xH20 containing about 41.5% ruthenium) in 500 milli-llters of water, adding a solution of 57.7 grams Or pota~-sium carbonate (K2C03) in 200 milliliters of ~ater ælowly and with vigorou~ stirring, ~eparatlng the precipitated mixture Or carbonates, drying at 120C under reduced pre~-sure, heatlng in a mu~fle furnace at 1000C for l hour, grinding and mixing, and then heating at about 1000C ~or 3 days with occasional grlnding and mixing, The resulting catalytic composltlon was ground and passed through a 325-mesh sieve screen. The filtrate ~rom the precipitated mixed carbonate~ contained an lnslgnificant amount of ruthenium. The X-ray dif~ractlon pattern o~ the catalytic composltion (obtained wlth nickel-filtered CuK radiation) contained line~ ~ith the following Angstrom spaclngs and relative intensities: 3.86, 18%; 2.73, 100%; 2.23, 15%;
2.20, 6%; 1.92, 32%; 1.72, 26%; 1.36, 8%; 1.35, 7%.
Application of Catalytic compo8ition to A Support Procedures simil~r to those o~ Example l were used to apply the above-described catalytic composition 0.2 0.8 ~ ~CoO.gRuO.l ~03 to two cylinders of "Torvex"
alumina ceramic honeycomb. me coated cylinders weighed 30 19.4% and 21.9% more than the dry uncoated cylinders.
. ~.

, ~79~
Catalytic Activity of Supported Catalytlc _ Composition The catalytic activity of the abo~e-de~cribed alumina ceramic honeycombs coated with the composition fSrO.21aO.8~7 ~oO gRuo 1 ~3 and binder was determined sub-stantially a~ described in Example 1 to obtain the data given in Table I.

Preparation of Catalytic Composition _ on a Support A support coated with a catalytic compo~ition hav-ing the nominal ~ormula ~SrO 2LaO 8 ~ CC0.9RUO.1 ~3 formed on the support was prepared by soaking a cylinder of "Torvex"
alumina ceramic honeycomb like that de~crlbed in E~ample 1 in a solution of 10.0 grams o~ lanthanum nitrate (La(N03)3.6H20), 1.22 gram~ of strontium nitrate (Sr(N03)2) J
7.57 grams of cobalt nitrate (Co(N03)2.6~20), and 0.735 grams of ruthenium chloride (RuC13.xH20, 39.71% Ru) in 100 milli-liters Or water, drying the cylinder at 120C under reduced pressure, heating the cylinder ror 30 minutes at 1000C, soak-ing the cylinder again in the solution, drying the cylinder, and heating the c~linder overnight at 1000C. The coated and heated cylinder welghed 3.4% ~ore than the dry uncoated cylinder.
Catalytic Activity o~ Supported Catalytic Composltlon The catalytic activity o~ the above-de~cribed ~lumina ceramic honeycomb coated with the compo~ition ~ rO 21a0 8 ~ ~CoO gRuo ~03 ~as determined substantially a~ descrlbed in Example 1 to obtain the data given in Table I.

~1~7~08~L

Preparation o~ Catalytic Composition A metal oxide having the nominal composition o~8 ~CoO. gRuo~ 1 ~o3 was prepared by dissolving 25 OE am~ of lanthanum nitrate (La(N03)3.6H20, 3.77 grams o~
barium nltrate (Ba(N03)2), 19 grams cobalt nitrate (Co(N03)2.6H20) and 1.79 grams of ruthenium chloride (RuC13.2~0, about 41.5% Ru) in 250 milliliters o~ water, adding slowly and with stirring a solution o~ 28.9 gram~ of potassium carbonate (K2C03) in 100 milliliters of water, separating the precipitated mixture of carbonates, drying at 120C under reduced pressure, heating in a mur~le furnace at 1000C for one hour, grinding and mixing, and heating at 1000C ~or 4 days with occasional grinding and m~xing. The resulting catalytic composltion was ground and passed through a 325-mesh ~ieve screen.
Application of Catalytic Compositlon to a Su~ort , Procedures similar to those of Example 1 were used to apply the aboYe-described catalytic compo~ition O 2LaO 8~7 ~CoO gRuo 1 ~3 to a cylinder of "Torvex" alumlna ceramic honeycomb. The coated cylinder weighed 16.6% more than the dry uncoated cylinder.
Catalytic Activlty of Supported Catalytic Compo~ition , The catalytic activity o~ the above-described alumina ceramic honeycomb coated with the compsotion ~aO 2Lao 8J ~coO gRuo 1 ~3 ~as determined substantially a~ described in Example 1 to obt~in the data given in Table I.

..

~,o7~

_XAMPLE 7 A metal oxide having the nominal composition 8 ~ CO gRUo 1 ~3 in which RE represents a mix-ture Or rare earth metal~ in substantially the proportionQ
in whlch they occur in monazite ore was prepared substantial-ly by the procedure de~cribed in Example 6 from 30.0 grams of mixed rare earth nitrate (RE(No3)3.5H20j containing nominal-ly about 48% Ce, 24% La, 17% Nd, 5% Pr, 3% Sm~ 2~ Gd, 0.2% Y, and 0.8% other rare earth metals by weight as the oxides), 3.74 grams of strontlum nitrate (Sr(N03)2), 23.1 grams of cobalt nitrate (Co(N03)2.6H20), and 3.74 grams of ruthenium chlorlde (RuC13.2H20, about 41.5% Ru). me X-ray dirfraction pattern of the black catalytic composition 80 obtained con-tained lines with the following Angstrom spacings and the indicated relative intensities: 3.87, 9%; 2.72, lOG%; 2.22, 10%; 1.92, 62%; 1.57, 22%; 1.56, 7%; 1.42, 7%; 1~35, 12%.
Application of Catalytic Composition to a Support Procedures similar to those of Example 1 were used to apply the above-descrlbed catalytic composition ~rO 2RE0 87 ~o gRUo 1 ~3 to a cylinder of "Torvex" alumina ceramlc honeycomb. The coated cylinder ~eighed 22.2% more than the dry uncoated cyllnder.
Catalytlc Activity of Supported Catalytic Com~osltion The catalytic activity o~ the above-described alumina ceramic honeycomb coated wlth the composition Cro~2REo~8;7 ~oO,gRuO~l ~03 and binder was determined sub-stantially as described in Example 1 to obtain the data given in Table I.

~74~

Preparation of Catalytlc Com~osition A metal oxide havlng thle nominal composition ~SrO.2LaO,8 ~ ~Coo~98Ruo~o2 ~3 wa~ made by substantially the procedure~ of Example 1 from 16.0 grams o~ lanthanum oxide (La203), 0.33 grams o~ ruthenium oxide (Ru02), 3.62 grams o~
~trontium carbonate (Sr(C03)2), and 14.31 grams Or cobalt carbonate (CoC03). The X-r~y dif~raction pattern of the resulting black catalytic composition wa~ not signi~icantly di~erent rrom that o~ a metal oxide havlng the nominal com-positlon SrO,2LaO 8CoO3. me æurface area o~ the ground composition determlned by the Brunauer-Emmett-Teller method, was 1.0 square meter per gr~m.
Application Or Catalytic Gomposltion to a Support The above-de~cribed composltion CSrO 2LaO 8 ~-~CoO o8Ruo 02 ~3 wa~ applied to a cylinder o~ "Torvex"
alumlna ceramic honeycomb substantially as descrlbed in Example 1, using a slurry containlng 7.5 gram~ o~ the com-position 2.0 gram~ of "Dlspal" alumina dlspersant and binder~and 3 drops of commerclal concentrated hydrochlorlc acid ln 17 mllllllter~ o~ water. me dried and heated ceramlc honeycomb cylinder weighed 24% more than the dried uncoated cyllnder.
Catalytlc Actl~ity o~ Supported Catalytlc Composltion me eatalytlc activlty o~ the above-described alumina ceramic honeycomb coated wlth the compo~ition 0.2 0.8 ~ ~Coo.98Ruo~o2 ~3 and binder was determined ~ub-stantially as described in Example 1 to obtain the data glven ln Table I.

.

.

74~

r ~r~R~ro~ talytic Com~osition A metal oxide having the nominal composition O~2laO~8 ~ ~oo~95Ruo.o5~ 03 ~aæ prepared substantially by the procedure of Example 6 using 400 gram~ of lanthanum nitrate (~a(N03)3.6H20), 49.0 grams of strontium nitrate (Sr(N03)2), 320 grams of cobalt nitrate (Co(N03)2.6H20), and 15.9 gram~ of ruthenium chloride (RuC13.xH20, 39.71~ Ru) in ~ liters of water and 461 grams o~ potas~ium csrbonate (K2C03) in 1500 mllliliters of ~ater. The resulting black catalytic compositlon had an X-ray dir~raction pattern ~imilar to an oxide having the formula SrO 2LaO 8CoO3 containing a trace o~ lanthQnum oxide (La203).
Applic~tion of Catalytic Composition to a Support The above-described catalytic composition .2L~o.8~7 ~CoO.95RU0~05 ~o3 was applied to cylinders of "Torvex~' alumlna ceramic honeycomb by procedures substanti-ally like those de~cribed in Example 1 to obtain cylinders cont~ining in one set (9A) 11.8~ to 16.1% catalyst compo~i-tion and binder and in another set (9B) 3.2% to 6.4% catalyst composition and binder.
Catalytic Activity of Supported Catalytic Composition .
The catalytic activity of the above-deæcribed ~lumina ceramic honeycombæ coated with the compo~ition O.2LaO.8 ~ ~ oO,95Ruo~o5 ~o3 and binder at a loading Or about 13% was determined subætantially a~ described in Example 1 to obtain the data ~iven in Table I, -~5-,, ,:

)740~

Preparation o~ Catalytic Composition A metal oxide of the composition ~Ko 2SrO 2LaO 6~-~oO 8Ruo 2 ~3 wa~ prepared from a mixture Or 2.97 grams o~
potaæsi~ carbonate, 3.17 grams of strontium carbonate, 10.51 grams of lanthanum oxide, 10.23 grams o~ cobalt car-bonate and 5.0 grams of ruthenium oxide dihydrate (43.5~ Ru) by heating for 4 dayæ in a ~urnace at 1000C ~ollowing the procedure o~ Example 1. The cataly~t composition ~o prepared was coated onto a cylinder of aluminwm ceramic honeycomb ~old under the trade name "Torvex" by the procedure of Example 1, the comblned weight of cataly~t and binder and support being 15.6% by weight greater than the uncoated support.
Cataly c Activity The catalytic activity o~ the above composition ln the reductlon of nitric oxide and the oxidation o~ carbon monoxide and the oxldation of propane i8 given in Table I.

Preparation o~ Catalytic Composition The cOmposition ~rO.2LaO.8;7 ~o.gPtO.1~703 w prepared by dissolving 35.2 grams of lanthanum nitrate (LA(N03)3.5H20), 4.45 gram~ o~ strontium nitrate (Sr(N03)2~, and 27.6 grams of cobalt nitrate (Co(N03)3.6H20) in 500 milliliters of water, addlng 40.3 grams of potas~ium car-bonate in 200 milliliters of water and 2.43 gram~ o~
platinum dioxide (PtO2, 84.2% Pt), separatlng the preclpitat-ed carbonates and added oxlde, drying at 120C under reduced pressure, and heating the dried mixture at 1000C ~or 4 d~y~
wlth daily grinding and mixing. The resulting black catalytic composition was ground and pa~sed throueh a 325-mesh sleve screen.

.
, ' . ' . ': ' ' ~ '~

~7~11 The X-ray dif~raction 01~ this catalytic composition showed it to be a nearly single-phase composition of the perov-skite crystal type, with a ~ew unLdentified line~ not attri-butable to platinum metal or to platinum dioxlde and an indi-csted cell volume Or 56.81 cubic Angstroms per ~ormula unit.
The ~ize o~ the unit cell reflected the introduction o~ the relatively large platinum ion into the crystal lattice of ~SrO,2La0.8~7 ~Co~03 (cell ~olume 56.13).
~E~1cat10n~ to a Sup~
Procedures similar to those o~ Example 1 were u~ed to apply the above catalytlc composition to a cylinder o~
"Torvex" alumina ceramic honeycomb. me coated cylinder weighed 15.8% more than the dry uncoated cylinder.
Catalytic Activity o~ Supported Composition me catalytic actlvity o~ the abo~e-described alu-mina honeycomb coated wlth the described compo~ition and binder Wa8 determined substantially as described in Example 1 to obtain the dats given in Table III.

~74~)8~

.:

p O Ll~ O Lr~
o o o~ ~ ~, ~11 H N ~ ~
~1 O
: O

~C I ,1o~ 0 00 . O

l ~ O ~
O r-l (~ N N N
. O

~ O Lt~
H ¦ O 0 1 N

v o~ O O O Lr~ O O
oo~ o cJ~
5; ~~ ~S ~_1 ~
CO ~ .4 01 0 N 0~
~ ~ r :, N
o '5 ~3 .~ O
~ .
i' E~ ~ V
5~ O o ~' H
o o o 'C o v c~ ~ 6) a) ..
H C ~
~3 V ~ N In O~

' ~07 Pre~aration of Catalytic Compositions __.
Metal oxldes having the nominal composition~
12A: [BaO lLaO ~ ~lo~gPto~] 3 12B: CsrO,2LaO,g [Co~9pdo~l] 3 were prepared and coated onto cyllnders of "Torvex" alumina ceramic honeycomb supports by sub~tantially the procedures de~cribed in Example 1, using the ingxedients, heating for the times and at the temperatures, snd obtaining the amounts of the compo~ition~ on the ceramic honeycomb which are glven in Table IV. The X-ray difrraction patterns Or these metal oxides indicated 12A: a maJor component ha~ing an expanded LaA103 pero~skite lattice, not more th~n about 5% La203, and le~ than 0,2% platinum in the metallic state.
12B: a pattern essentlally the same a~ that o~
[SrO 2L8o.8] ~COo~gPdo~l]o3 (ExAmple 13D~ indicating the presence o~ less than 2% 2 3' 2 3' detectable palladium in the metallic state.
Catalytic Activit~
The catalytic actiYity of these composition~ in the reductlon of n~tric o~lde by carbon monoxide, the oxidation of earbon monoxide, and the oxidstion of propane, determined by the procedures de~cribed in Example 1 before and a~ter heating the composltions on their supports for an additional 100 hour~
at about 900C9 are indicated by the data in Table V.

' ' ' , ~ , ~ : ' , ~7401!3~

TABLE IV
reparation o~ _mposition~ o~ Example 12 Grams o~ Ingredients Employed Example: 12A 12B
Ingredients Barium oxlde, BaO 1.43 --Strontium carbonate, SrC03 -- 16.42 Lanthanum oxide, La203 13.33 72.72 Aluminum oxide, A1203 4.18 ~-Cobalt carbonate, CoC03 -- 59.66 Platinum oxide~ PtO .xX O 2.19 --83.37% Pt 2 2 Palladium oxide, PdO.XH20, -- 8.00 74.18% Pd Days heated ~n furnace 4* 4 Furnace ~emperature, C 900 900 Percent composition and binder on support 15.3 14.5 *Followed by 60 hours at 1,400C before grinding and passing through a screen.
TABLE V
_talytic Acti~ity of Compositions of Example 12 Composltion: 12A 12B 12B
Hours at 900C~
Reduction of Nitri~ Oxlde : ~Light-of~t~ temp., C 320 280 360 25% conversion, C 370 310 395 50% conversion, C 425 465 430 90% conversion, C 510 540 485 Oxid~tion o~ Carbon Monoxide "Light-orf" temp., C 305 290 230 25~ conversion, C 320 320 235 50% converæion, C 340 350 260 90% conversion, C 370 400 290 Oxidation o~ Propane IlLight-o~" tempO, C 420 385 335 25% conversion, C 490 505 ~25 50% conversion, C 550 - 515 90% conversion, C - - --5o-.
- . :
.

~7~8~

Preparat on of Catal~tic ~
Metal oxides having the nominal compositions 13A ~rO o6Lao.9~ Elo. 80~00 16RUO O~ 3 13B: ~SrO lLaO.~ Elo gRUoO ~ 3 13C: ~rO~3Lao~ ~eO.9RUO.~ 3 13D CrO.2Lao,~ [o gRho ~ 3 were prepared and coated onto cyllnders o~ "Torvex" alumina ceramic honeycomb supports by ~ubstantially the procedures de~cribed in Example 3, using the ingredients, heating for time~ and at the temperatures, and obtainlng the amountæ o~
the composltions on the ceramic honeycomb which are given in Table VI. The X-r~y dif~raction patterns of these metal oxides indicated 13A: a diætorted perov~kite crystal structure like LaA103, with no suggestion of the pre~ence o~ the cobslt spinel CoA1204.
13B: a single phaæe having a structure of the perov~kite type similar to that of LaA103. Crystal cell dimen-sions calculated from some o~ the line3 indicated a cell volume Or 55,10 cubic Angstroms per ~ormula unit. A solid solution of 90% LaA103 (unit cell volume 54.46 cubic Angstroms) and 10% SrRuO3 (unit cell volume 60.45 cubic Angstroms) is calculated to have a unit cell volume of 55.05 cubic Angstroms 13C: an expanded LaFeO3-type perovskite crystal structure with no evidence o~ binary metal oxides.
13D: a ~aCoo3-type crystal ~tructure with an expanded lattice nnd an X-ra~ pattern ~ubstantially identical ~7~

to thQt o~ the perovskite [SrO 2LaO 8]~CoO,gRuO~1~03 (Example 2) _a alytic _ tivity The catalytic activity o~ these composltions in the reduction Qf nitric oxide by carbon monoxide~ the oxidation of carbon monoxide, and the oxidation of propane, determined by the procedures described in Example 1 before and after heating the compositions on the ~upports for an additional 100 hours at about 900C, are indicated by the data in Table VII.

, . . .:

~)7'~3~

_ABLE VI
Preparation Or Co po~itions o~ Example 13 Grams o~ Ingredients Employed Example: 13A 13B 13C 13D
Ingredients Strontlum nitrate, SrC03 6.24 4.15 25.0 40.75 Lanthanum nitrate, ~ 51.88 La(N3)3-6H2 Lanthanum nitrateJ 200 76.2 119 --La(N3~3-6H2 Aluminum nitrate,147.4 -- -- --Al(N3)3 6H2 Aluminum nitrate, -- 66.o -- --Al(N03)3-9H2 Cobalt nitrate 29,9 -- -- 40,75 C(N3)3 6H2 Ferric nitrate, -- -- 143 --Fe(N03)3 9H2 Ruthenium chlorlde,5.02 5.0 10.0 --RuC13.xH20, 39.71% Ru Rhodium chloride, -- -- -- 4.00 RhC13.xH20, 40% Rh Potas6ium carbonate,234.96 95.6 165.9 63-3 D4ys heated in ~urnace 4 4 4 4 Furnace Temperature, C1000 950 950 950 Percent composition and15.4 16.2 16.7 21.1 binder on support .

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1~77~81 Preparation of Catalytic Compositions Metal oxides havlng the nominal compoæitions 14A: ~rO lLaO~ ~Nio~ ~p ol~ ~ 3 14B: [B~o 4LaO.~ ~oO.9PtO ~ 3 14C ~SrO 4LaO ~ ~OoogPtO 3 o3 were prepared and coated onto cylinders of "Torvex" alumlna ceramic honeycomb supports by substantlally the procedures des-cribed in Example 11, uQing the ingredients, heating for the times and at the temperatures, and obtaining the amount~ of the composition~ on the ceramic honeycomb which are given in Table VIII. me X-ray dirfraction pattern~ Or the~e metal oxides lndicated 14A: a LaNiO3 perovskite lattice containing NiA1204 and lesæ than about 0.2% Or NiO and platinum metal.
14B: a lattice-expanded ~aCoO3 perovskite structure with no evidence o~ binary oxides or metallic platinum.
14C: a perovskite crystal structure similar to that of IaCoO3 but with displacement to larger d-spacings and less than about 0.2% of platinum metal.
Catalytlc Activity me catalytlc activity of these compo~itions in the reduction o~ nitric oxide by carbon monoxide, the oxidation of carbon monoxide, and the oxidation of propane, determined by the procedures described in Example 1 before and after heating the composltions on their ~upports ~or an additional 100 hour~
at about 400C, are indicated by the data in Table IX~

~7~
T~BLE VIII
Preparation o~ Compositions of Example 14 G:ramæ o~ Ingredients ~mployed Example: 14A 14B 14C
Ingredlents Barium nitrate, Ba(N03)2 -- 126 --Strontium nitrate, Sr(N03)2 10.9 ~~ 98.4 Lanthanum nitrate, La(N3)3-5H2 200 -- 301 Lanthanum nitrate, L~(N3)3-6H2 -- 300 --Cobalt nitrate, Co(N03)2.H20 -- 317~2 303 Nickel nitrRte, Ni(No3)2.6H2o 134-2 -- --Potaæsium cfirbonate, K2C03 200.1 441 422 Platinum oxide, PtO.xH20, 8109~ Pt 12.34 ~~ 27.9 Platinum oxide, PtO.~H20, 83.37~ Pt -- 28.3 ~~
~ays heated in ~urnace 4 4 4 Furnace temperature, C 950 900 950 Percent composition and binder on 8upport 22.4 14.4 15.1 ~07~

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Preparation of Catalytic Compositions Metal oxides having the nominal compositions 15A: Ccao~5Bao~3 ~io gP 0.~ 3 15B: [SrO 2LaO~ ~CrO.9RUOr~ 3 15C ~aO.gLaO.~ ~lo, gPto~ 3 15D: [Rbo 2BiO.~ [Ti-9RU ~ 3 were prepared and coated onto cyllnders of "Torvex" alumina ceramic honeycomb ~upports by ~ubstantially the procedures de~crlbed in Example 11 using the ingredients, heating for the times and at the temperatures, and obtaining the amounts of the compositions on the ceramic honeycomb which are given in Table X. The X-ray di~fraction patterns of these metal oxldes indicated:
15A: a pattern ~imilar to that of the perovskite BaTiO3 with shorter d-spacings and traces (les~ than 0.2%) o~ the perovskite CaTiO3 and o~ platinum in the metallic state.
15B: an unldenti~ied pattern, with no evidence of binary metal oxides.
15C: an expanded LaA103 perovskite lattice containing not more than 5~ La203, and traces (less than 0.2%) o~
platinum ln the metallic state.
15D: a pattern similar to that o~ Bi4(TiO4)3, with no evidence of binary metal oxides.
Catalytic Activity me c~talytic activity o~ the~e compositions ln the reduction of nitric oxide by carbon monoxide, the oxidation of carbon monoxide, the oxidation of propane, determined b~ the procedures degcribed in Example 1 before and a~ter heating the compositions on their supports for an additional 100 hours at about 900C, are indicated by the data in Table XI.

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Claims (36)

The embodiments of the invention in which an ex-clusive property or privilege is claimed are defined as follows:

1. A compound having a perovskite type ABO3 crystal structure, wherein

1. the sites of Type A are occupied by cations of at least two different metals selected from the group consisting of the metals from groups 1A, 1B, 2A, 2B, 3B, 4A, 5A, the lanthanide rare earth metals and the Actinide rare earth metals, each occupying at least 1% of the Type A cation sites and having an ionic radius between 0.8 and 1.65 .ANG.
and 2. from about 1% up to about 20% of the sites of Type B are occupied by ions of the platinum group metals, selected from the group consisting of ruthenium, osmium, iridium, rhodium, palladium and platinum, and the remaining sites of Type B
are occupied by ions of nonplatinum group metals selected from the group consisting of the metals from groups 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6B, 7B, 8, the Lanthanide rare earth metals and the Actinide rare earth metals, having ionic radii between about 0.4 and 1.4 .ANG..

2. A compound of claim 1 wherein at least about 50% of the remaining sites of Type B are occupied by non-platinum metal group ions of variable valence.

3. A compound of claim 2 wherein said metal ions of variable valence have atomic number of from 22 to 29 inclusive.

4. A compound of claim 3 wherein said metal ions of variable valence are iron, nickel or cobalt ions.

5. A compound of claim 4 wherein said A site metal ions are selected from ions of potassium, strontium, barium, lanthanum and metals of atomic number 58 to 71, inclusive.

6. A compound of claim 5 wherein said ions of the platinum group metals are selected from ruthenium and platinum ions.

7. A compound of claim 2 wherein at least 5% of the said remaining B sites are occupied by metal ions of a variable valence in a first valence state and at least a further 5% of the said remaining B sites are occupied by ions of the same metal of variable valence in a second valence state.

8. A compound of claim 7 wherein said A site metal ions are selected from ions of potassium, strontium, barium, lanthanum and metals of atomic number 58 to 71 inclusive.

9. A compound of claim 8 wherein said ions of platinum group metals are selected from ruthenium and platinum ions.

10. A compound of claim 9 wherein said variable valence metal is selected from iron, nickel and cobalt.

11. A compound of claim 2 wherein all of the remaining sites of Type B are occupied by non-platinum group metal ions of variable valence.

12. A compound of claim 11 wherein said metal ions of variable valence have atomic number of from 22 to 29 inclusive.

13. A compound of claim 12 wherein said metal ions of variable valence are selected from iron, nickel and cobalt ions.

14. A compound of claim 13 wherein said A site metal ions are selected from ions of potassium, strontium, barium, lanthanum and metals of atomic number 58 to 71, inclusive.

15. A compound of claim 14 wherein said ions of the platinum group metals are selected from ruthenium and platinum ions.

16. A compound of claim 11 wherein at least 5% of the said remaining B sites are occupied by non-platinum metal ions of a variable valence in a first valence state and at least a further 5% of the said remaining B sites are occupied by non-platinum metal ions of the same metal of variable valence in a second valence state.

17. A compound of claim 16 wherein said non-platinum metal ions of variable valence have atomic number of from 22 to 29 inclusive.

18. A compound of claim 17 wherein said non-platinum metal ions of variable valence are selected from iron, nickel and cobalt ions.

19. A compound of claim 18 wherein said A site metal ions are selected from ions of potassium, strontium, barium, lanthanum and metals of atomic number 58 to 71, inclusive.

20. A compound of claim 19 wherein said ions of the platinum group metals are selected from ruthenium and platinum ions.

21. A compound of claim 20 having the formula [SrxLa1-x] [Co1-yRuy]O3 wherein y is from 0.01 to 0.2 and (1-x) is from 0.95 (1-y) to 0.5 (1-y).

22. A compound of claim 20 having the formula [SrxLa1-x] [Co1-yPty]O3 wherein y is from 0.01 to 0.1 and (1-x) is from 0.95 (1-y) to 0.5 (1-y).

23. A compound of claim 1 wherein at least about 50% of the said remaining sites of Type B are occupied by ions of non-platinum group metals having a single fixed valence.

24. A compound of claim 23 wherein said metal is a metal of Group IIIa of the periodic table.

25. A compound of claim 24 wherein said metal is aluminum.

26. A compound of claim 25 wherein said A sites are occupied by metal ions selected from ions of potassium, strontium, barium, lanthanum and metals of atomic number 58 to 71 inclusive.

27. A compound of claim 25 wherein said ions of platinum group metals are selected from ruthenium and platinum ions.

28. A compound of claim 23 wherein all of said remaining B sites are occupied by ions of non-platinum group metals having a single, fixed valence.

29. A compound of claim 28 wherein said metal is a metal of Group IIIa of the periodic table.

30. A compound of claim 29 wherein said metal is aluminum.

31. A compound of claim 30 wherein said A sites are occupied by metal ions selected from ions of potassium, strontium, barium, lanthanum and metals of atomic number 58 to 71 inclusive.

32. A compound of claim 31 wherein said ions of platinum group metals are selected from ruthenium and platinum ions.

33. A catalyst comprising a compound of claim 1 on a shaped support.

34. A catalyst of claim 33 wherein said compound is preformed and is affixed to the support with a binder.

35. A catalyst of claim 34 wherein said support is alumina.

36. A catalyst of claim 35 wherein said support is shaped in the form of a honeycomb.