CA2003944A1

CA2003944A1 - Phosphate-containing ceramic structure for catalyst support and fluid filtering

Info

Publication number: CA2003944A1
Application number: CA002003944A
Authority: CA
Inventors: Irwin Morris Lachman; Jimmie Lewis Williams; Kenneth Elmer Zaun
Original assignee: Corning Glass Works
Current assignee: Corning Inc
Priority date: 1989-01-10
Filing date: 1989-11-27
Publication date: 1990-07-10
Also published as: JPH02229773A; EP0377960A2; EP0377960A3; US5039644A

Abstract

PHOSPHATE-CONTAINING CERAMIC STRUCTURES FOR
CATALYST SUPPORT AND FLUID FILTERING

Abstract of the Invention A monolithic ceramic structure, useful as a support for catalytic material or as a fluid filter, has a high surface area phase which consists essentially of a porous metal oxide material, at least 50% by weight of which is alumina, titania, and/or zirconia, and phosphate dispersed substantially throughout the porous metal oxide material.
The presence of the phosphate stabilizes the porous metal oxide material against thermal degradation during sintering or exposure to elevated temperatures encountered in cata-lytic service and thereby aids in the retention of higher overall surface area in the monolithic structure.

Description

~ ~ac~nan-Williarns-Zaun 35-3-1 ~0(~39~

PHOSPHATE-CONTAINING CERAMIC STRUCTURES FOR
CATALYST SUPPORT AND FLUID FILTERING

~; Background of the Invention :'.''~
` This lnvention is directed to high surface area mono-, `~ 5 lithic structures composed of sintered ceramic oxide materials which have high porosity. The structures are useful as filters for fluids and as catalytic substrates in ~; that they provide high s~rface area for particular filtra-tion or for deposition of catalytic material. The inven-tion is more particularly directed to structures in which the ceramic material is primarily alumina, titania, or zirconia which has been modified, prior to firing or sintering, by admixture with a phosphate material that generates P2O5 upon heating. The structures are particu-~ 15 larly useful as catalyst supports in the conversion of - automotive exhausts and in reduction of NOx emissions from ~- industrial sources, and as fluid filters, such as those used in diesel engines.
Conventional monolithic ceramic catalyst supports consist of an underlying ceramic support material with a coating of high surface area material upon which the catalyst itself is actually deposited. In particular, the ceramic support is prepared by sintering a mold of clay or other ceramic oxide (alumina, titania, cordierite, etc.) at a temperature suf~iciently high to densify and strengthen the material. Temperatures high enough to result in eiiective sintering, however, also cause pore shrinkage and ' ~ , . .

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other microstructural changes that result in the sintered material's having a very low surface area. Consequently, the sintered ceramic must be coated with another material having a higher surface area, often a ceramic material 5 itself that has not been sintered or pre-reacted, on which to actually deposit the catalyst. This procedure of applying a high surface area "wash-coat" on the low surface area ceramic wall is disclosed, for example, in U.S. Patent Nos. 2,742,437 and 3,824,196.
In addition to the exposure to high temperature during sintering, however, catalyst support structures can also be exposed to elevated temperatures in service. The surface area of a wash-coat can be substantially degraded, and the surface area of the underlying ceramic may also further be reduced in some instances, because of the high service temperatures, such as those of automotive exhaust gases, to ` which they are e~posed. It is therefore desirable to use ceramic materials that are, or can be modified to be, resistant to loss of surface area when exposed to elevated temperatures either during firing or service. One such material is a mixture of 50-93% by weight alumina and 7-50%
by weight silica as disclosed in U.S. Patent No. 4,631,269 (Lachman et al, issued December 23, 19~36).
It is an object of the present invention to provide an improved monolithic structure that can be sintered to provide structural strength and integrity without loss of appreciable surface area. It is a further object of the invention to provide a structure that resists thermal degradation o~ its porosity and available surface area despite exposure to elevated temperatures in catalytic conversion processes.

Summary of the Invention The present invention provides a~ improved monolithic structure, useful as a filter or catalyst support, compris-ing (1) a sintered ceramic phase oi a porous metal oxide, :

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at least 50~ by weight of which is alumlna, titania, and/or zirconia, and ~2) about 0.5-35% by weight of P2O5 (based on the total weight of the P205 and the alumina, titania, and/or zirconia) substantially dispersed throughout the ; S porous metal oxide phase. In preferred embodiments directed to its use as a catalyst support structure, the monolith further contains catalytic metals, such as transi-tion metals (including rare earth metals), or their oxides, distributed throughout the sintered ceramic phase of porous metal oxide or on the surfaces of the porous metal oxide.
The combination of P2O5 with ceramic oxide material as ~ described herein provides a supporting substrate for - catalyst that retains high surface area and effective pore size distribution despite being subjected to the elevated `~ l; temperatures of ceramic firing and catalytic service.
Efficient catalytic activity, which is dependent on surface area and porosity, can therefore be maintained over longer service periods.

Brief Description of the Drawinqs Figure 1 is a graph depicting the surface area re-tained, after firing, of a P2O5-containing alumina material of the present invention.
Figure 2 is a graph depicting the surface area re-tained, after firing, of a P2O5-containing titania material of the present invention.

Detailed Descri~tion of the Invention According ts the present invention, a sintered mono-lithic structure is provided which comprises a high surface area of porous ceramic metal oxide, at least 50% by weight of which is alumina, titania, and/or zirconia, and about 35 0.5-35% by weight of P2O~ or equivalent phosphate-containing compound dispersed substantially throughout the porous metal oxide material. ~he struoture is prepared by ;

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a~mixing the porous oxide material and a phosphate material capable of generating P2O5 at or below the firing tempexa-ture, forming the admixture into a desired shape, and firing the shape according to conventional techniques of the ceramic arts to form a structure having substantial strength and high surface area. It has been found that the presence of the phosphate material, in intimate mixture with the ceramic porous oxide material, permits the oxide to be ~ired to an effective level of strength while retain-ing an acceptable surface area and catalytically-effective pore size distribution.
The porous oxide materials suitable for use are those which, after calcining, have a surface area of at least 20 square meters per gram, preferably at least 100 square meters per gram, and most preferably at least 200 square meters per gram. (As used herein, "calcining" means heating a material to a temperature sufficiently high to - substantially eliminate volatiles but below the temperature at which the material begins to densify.) At least 50% by weight of the porous oxide material is alumina, titania, zirconia, or a mixture of these three. The balance, if any, of the porous oxide material can be any other ceramic material that has commonly been used as a catalyst support in the past and which has the above-described characteris-tics. Preferably, the porous oxide material is at least 75-80% by weight of alumina, titania, and/or zirconia (hereinafter, the "core metal oxides"). In particularly preferred embodiments, substantially all the porous oxide material is one or more of these core metal oxides.
The aluminas useful as the porous metal oxide are those which, upon calcining or firing, provide gamma-alumina or other transition aluminas having the specified surface area. Colloidal gamma-alumina can be ~Ised directly or materials which generate a transition alumina upon calcining, such as alpha~alumina monohydrate or alumina trihydrate, can also be used. The colloidal gamma-alumina is generally in the form of particles of 1 micron size or X~ 94~

less. When alpha-alumina monohydrate or alumina trihydrate is used, the particle size can be from less than 1 micron up to 100 microns, but preferably less than about 75-80 microns. Suitable commercially available materials of this kind are Kaiser SA substrate alumina, CATAPAL alumina available from Vista Chemical Company, and DISPURAL alumina monohydrate from Remet Chemical Corporation.
The alumina coMponent can also be introduced in the form of a precursor such as a hydrated alumina, a hydrolyzed aluminum alkoxide, or aluminum chlorohydrate.
The hydrated aluminas are preferably in the form of an aqueous suspension and are commercially available, for example, from the Ethyl Corp. The most preferable aluminum alkoxide is hydrolyzed aluminum isopropoxide, which is commercially available as a dispersion in alcohol. For example, a dispersion of aluminum isopropoxide, 30-35% by weight in isobutanol, is available from the Alpha Products Division of Morton Thiokol Inc. Aluminum chlorohydrate is available in the form of an aqueous solution, for example, as CHLORHYDROL 50% or REHABOND CB-65S from Reheis Chemical Co. Aluminum chlorohydrate is also available in solid particulate form, for example as CHLORHYDROL Powder from Reheis Chemical Co.
High surface area titanias suitable for use as the ceramic porous metal oxide of this invention are commer-cially available, for example, from the Degussa Corporation as P25 TiO2. The titania can also be introduced in the form of a precursor such as a suspension of an amorphous hydrated titanium oxide, which can be in the form of a hydrolyzed titanium alkoxide, such as titanium isopropoxide (tetraisopropyl titanate), or a slurry of titanium hydrate.
Slurries of titanium hydrate are commercially available, for example from SCM Corp. In all cases, the solid titania or solid portion of the titania precursor is generally in particulate form with a primary particle size less than about 100 microns, preferably less than about 75-80 microns, and more preferably less than 20 microns.

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The zirconia material useful in the practice of the invention can generally be in any form heretofore used in the ceramic arts. Generally, a pre-reacted zirconia in particulate form with a primary particle size in the same ranges as described immediately above is used. The zirconia can also be added in the form of a precursor. The preferred precursor is a suspension of an amorphous hydrated zirconium oxide, which can be in the form of a hydrolyzed zirconium alkoxide (such as zirconium n-propoxide) or a slurry of zirconium hydrate.
Up to 50% by weight of the porous metal oxide materialof the monolith can be composed of one or more ceramic metal oxides other than the above-described core metal oxides. This component of the monolith can be any of the well-known sinterable materials capable of providing mechanical strength and thermal properties in monolithic supports as heretofore prepared by those skilled in the art. Preferably this material is selected from cordierite, mullite, clay (preferably kaolin clay), talc, spinels, silicates such as lithium alumino-silicates, alpha alumina, aluminates, aluminum titanate, aluminum titanate solid solutions, stabilized zirconias, silica, glasses, and glass ceramics. Any mixture or combination of these materials can be used.
Spinels useful in the present invention are the magnesium aluminate spinels heretofore used as catalyst supports, including spinel solid solutions in which magne-sium is partially replaced by such other metals as manga-nese, cobalt, zirconium, or zinc. Preferred spinels are magnesium aluminate spinels having 1-7% by weight alumina in excess of 1:1 MgO.Al2O3 spinel; that is, those having about 72.0-73.5 weight percent A12O3 (balance MgO). Spinels of this kind can be prepared by coprecipitation or wet-mixing of precursors of alumina and magnesia, followed by drying and calcining. Such a procedure is described in U.S. Patent No. 4,239,656, the disclosure of which is hereby incorporated by reference as filed. As a supplement ~)3~4~

to this disclosure, however, it has been found that cal-cining of the spinels should normally not exceed 1300C for 2-2.5 hours. Calcining temperatures below 1200C are preferred. Suitable alumina precursors for preparation of the spinels are hydroly~ed aluminum alkoxides or hydrated aluminas, both of which are commercially available. Mag-nesium oxide component powders found to be suitable are magnesium hydroxide slurry, about 40 weight percent MgO, available from Dow Chemical Company, or hydrated magnesium carbonate.
High surface area silicas that can be used in the practice of the present invention are the amorphous silicas of about 1-10 microns or sub-micron particle size such as Cabosil3 EH-5 colloidal silica, available from Cabot Corporation. Colloidal silica derived from gels, such as Grade 952 from the Davison Chemical Division of W. R. Grace & Co. can also be used.
Cordierite, one of the preferred ceramic materials for use as the additional substrate material herein, can be in the precursor or "raw" form which becomes true cordierite upon heating, or can be used in pre-reacted form. When raw cordierite is used, it is preferred that up to 10% by weight, based on cordierite weight, of B2O3 be added to the batch to initiate cordierite formation at lower than usual temperatures and to impart additional strength.
Unless otherwise specified above, these additional ceramic materials should be in particulate form, preferably of a size finer than 200 mesh (U.S. Standard) and more prefera~ly finer than 325 mesh (U.S. Standard~. With such characteristics, the ceramic material can be more easily sintered, during the subsequent formation of the monolith, at temperatures below those at which surface area of these materials, as well as the core metal oxides, might be adversely affected.

3 5 The phosphate component of the invention is incorpo-rated into the monolith by admixing into the starting batch a compound capable of generating P2O5 at or below the 2~ 94'~

firing or sint~ring temperature to be used. The source of the phosphate is not critical. Phosphoric anhydride itself or phosphoric acid can be added, or a phosphate precursor, preferably one soluble in water, can be used. Preferred precursors of this kind are (NH4)2HPO4 tdibasic ammonium phosphate) and Al(H2PO4)3 (aluminum dihydrogen phosphate).
Generally, the phosphate material is added to the batch in an amount that will provide about 0.5-35% by weight of P2O5, based on the combined weights of P2O5 and the core porous oxides. Preferably, the final weight of P2O5 in the monolith will be about 1-25 weight percent.
When substantially all of the core porous oxide is alumina, a more preferred final weight percentage of P2O5 is about 1-10%, and most preferably 3-7%. When the core porous oxide is substantially all titania, a more preferred final weight percentage of P2O5 is about 1.5-15%, and most preferably about 3-10%. When substantially all of the core porous oxide is zirconia, a more preferred final weight percentage of P2O5 is about 1.5-15%.
The monolithic structures of this invention are prepared by admixing into a substantially homogeneous batch (a) the porous metal oxide material, (b) the phosphate-generating material, and optionally (c) a temporary binder.
Preferably, 1-30% by weight of temporary binder, ~ased on the total katch weight, is used. Any binder material conventionally used in ceramic catalyst support manufacture is suitable. Preferred are binders that are decomposed and :
burned-off at temperatures of about 250-600C. Examples are disclosed in: "Ceramic Processing Before Firing,l- ed/
by George Y. Onoda, Jr. & L.L. Hench, John Wiley & Sons, ~ New York; "Study of Several Groups of Organic Binders Under Lo~-Pressure Extrusion," C.C. Treischel & E.E. Emrich, Jour. Am. Cer. Soc. (29), pp. 129-132, 1946; "organic (Temporary) Binders for Ceramic Systems," S. Levine, Ceramic Age, (75) No. 2, pp. 39+, January 1960; and "Tempo-rary Organic Binders for Ceramic Systems" S. Levine, Ceramic Age, (75) No. 2, pp. 25+, February 1960. The most ~, .
, .

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g preferred binder is methyl cellulose, available as METHOCEL
A4M from the Dow Chemical Co.
Mixing of the batch ingredients is preferably performed in a step-wise procedure in which any dry ingredients are first blended together. This preliminary dry-blending operation can be performed in any conventional mixing equipment, but the use of a Littleford intensive mixer is preferred. The dry mixture is then plasticized by being further mixed, preferably in a mix muller, with a liquid medium (preferably water) which acts as a plasticizer. During this stage, all remaining constituents are added. Up to about 1% by weight, based upon total mixture weight, of a surfactant such as sodium stearate can also be added to facilitate mixing and flow for subsequent processing. Mixing of all constituents should be continued until a homogeneous or substantially homogeneous plasticized mass is obtained.
To effect further mixing, the plasticized batch can be extruded through a "spaghetti" die one or more times.
Ultimately, the batch is formed into the desired "green"
shape for the monolithic structure, preferably by extrusion through a die or by injection molding. The material processing method of this invention is particularly well suited to the preparation of structures in the shape of thin-walled honeycombs and wagon-wheels. The preferred shape is that of a honeycomb having about 25 2400, more preferably 200-400, through-and-through cells per square inch of frontal surface area (equivalent to about 4-370, more preferably about 30-60, cells per square centimeter of surface area~.
Finally, the "green" structures are fired in order to harden the material. The firing step generally takes plac~
at 500-1200C, although the use of temperatures belo~ about 1100C are preferred. For most ceramic materials, the temperature selected and the duration of the firing period will result in actual sintering of the material. This is preferred but not necessary. The strength requirements of X6~33~3~

the i.ntended end use of the structure will determine for the s~illed artisan whether the additional densification and hardening provided by fully sintering the material will be necessary. The firing/sintering step can be conducted in an inert atmosphere or in one which promotes either reduction or oxidation, depending on the presence and identity of catalytically active metal compounds in the batch, as discussed more fully below. Optionally, the firing/sintering step can be preceded by drying the shapes 10 at about 100-120C, preferably by steam heat.
In the fired article, the P2O5 is dispersed substan-tially throughout the porous metal oxide material. As those skilled in the art will recognize, however, the P2O5 may not necessarily exist as a free phase but may combine with the porous metal oxide materials to form phosphate com-pounds or complexes. For e~ample, AlPO4 and 5Tio2-2p2os are the common result of firing a phosphate-generating material with alumina and titania, respectively. In one particularly preferred embodiment of this invention, the final monolith consists essentially of alumina and about 4-23% by weight AlPO4. In another particularly preferred embodiment, the final structure consists essentially o~
titania and about 5-12% by weight 5TiO2-2P2O5. The pres-ence of P2O5 dispersed substantially throughout the ceramic metal oxide material aids its retention of high surface - area despite elevated firing, sintering, or service temper-::~ atures. This benefit is illustrated in the Fiqures. With particular reference to Figur~ 1, there is shown a graph of temperatures versus surface area retained after a 6-hour heat soak for a batch material consisting of 1~0% alumina and a batch material consisting of 87% by weight alumina and 13% by weight AlPO4. In Figure 2 there is shown a graph of temperature versus surface area retained after a 6-hour heat soak for a batch material of 100% titania and a batch material of 92% by weight titania and 8% by weight 5Tio2-2P2o5. In both cases, the surface area retained ~ [)039~
~11-after firing is shown to be greater for the phosphate-containing material than for the control.
The monolithic supports of this invention may have some catalytic activity of their own by virtue of the chemistry and structure of the high surface area phosphate-containing porous oxide phases. Nevertheless, the support structures of this invention are also intended to carry additional catalytically active ingredients on the surfaces thereof. (As used herein, the term "surfaces" refers to those surfaces of the monolithic support, including surfaces forming the pore cavities, that are normally intended to be in contact with the work stream of material to be catalyzed.) This catalytically active material can be any of the metallic catalysts heretofore used for NOx 15 reduction, for general chemical processing, or ~or automo- -tive exhaust catalysis. Preferred catalytic materials are the transition metals (including the rare earth metals) and metals of Group IIB. The metals can be used in elemental form or in the form of their oxides~ Preferred metals are zinc and such transition metals as tungsten, platinum, palladium, molybdenum, iron, manganese, vanadium, and copper. These additional catalytic ingredients can be deposited on the surfaces of the monolith by methods well known in the art, such as by preparing a solution or slurry of the materials for spraying, dip-coating, or impregnating the monolithic support.
In a particularly preferred embodiment, however, the additional catalytic ingredient is admixed directly into - the original batch and then co-extruded and sintered with the porous metal oxide material and phosphate material.
Generally the catalytic material is incorporated into the batch in an amount of about 3-20 weight percent, preferably 5-10 weight percent, based on the total batch weight. In this embodiment, it is preferred that the admixed catalytic material be in particulate form with a primary particle size no greater than about 20 microns, preferably no greater than about 2.0 microns, and most preferably no .. i ~39~

greater than about 1.5 microns. In one embodiment of the invention, this reduced particle size is obtained by slurrying the oxide of the catalytic metal, or a precursor therefor, with distilled water, and then adjusting the pH
and heating to dissolve the material. After all the material is dissolved, a portion of the ceramic oxide material to be used in the monolithic catalyst support is added to the solution. The resultant mixture is then neutralized, with a slight excess of the required acid or base, to precipitate very fine particles of the catalytic metal oxide so that they are substantially intimately admixed with particles of the porous ceramic oxide. The solids are separated by centrifugation and the resultant wet cake is then admixed with additional porous metal oxide material and phosphate material to prepare the monolith as earlier described. As a further alternative, the wet cake remaining a~ter centrifugation can be calcined at a temper-ature of about 250-300C. The calcined material is then milled to a size finer than 100 mesh, preferably finer than 200 mesh. In this form, the material contains very fine particles (generally less than about 2.0 micron) of cata-lytic material intimately admixed with finely divided particles of the porous metal oxide material. The monolith is then prepared by admixing this calcined and milled material, as earlier described, with additional porous metal oxide material and phosphate material.
`~ In another aspect of this invention, a composite monolith is provided in which 2 high surface area support phase, consisting essentially of the core metal oxides and 0.5-35~ by weight of the phosphate material, is combined with a separate phase of ceramic material that, upon sintering, provides the actual structural integrity and strength to the monolith. In this embodiment, a pre-formed mixture of the core porous o~ide material and phosphate material is coextruded with the sinterable ceramic struc-tural material in a single step, so that the two phases are physically integrated in their green states, but the high 4~

surfac~ area phase remains as a separate and discrete phase within the ceramic matrix after the monolith is fired.
Composite monoliths of this kind, in which the high surface area support phase is a specific mixture of alumina and silica, are disclosed in U.S. Patent No. 4,631,269 issued December 23, 1986, to Lachman et al. The disclosures of this patent, which are hereby incorporated by reference, can be followed to prepare composite monoliths in which the high surface area support phase is the mixture of core porous metal oxide and phosphate material of the present invention.
The following examples are illustrative, ~ut not limiting, of the invention.

Example 1 Three batches of phosphate-containing alumina material (designated below as lA, lB, and lC) and one control batch (10q% alumina, no phosphate addition) were prepared, extruded, shaped into honeycomb monoliths, and sintered, and their properties tested. The phosphate-containing monoliths were prepared from batch ingredients as follows:

Composition (parts by weight) Inqredient Ex. lA Ex. lB Ex. lC
A12O3 H2O (CATAPAL-B, 87.4 92.0676.94 Vista Chem. Co.) Al2(OH)5Cl (CHLORHYDROL 50%, - - 8.16 aqueous solution, Reheis Chem. Co.) A ( 2 4)3 12.6 - 14.9 (50% in water) (NH4)2HPO4 (Baker Chem. Co.) 7.94 METHOCEL (Dow Chem. Co.)6.0 6.0 6.0 Distilled water 38.3 40.8 35.0 ~ 39~

In each case, the ingredients were combined in a mix muller and the batch mixed until substantial homogeneity and plasticity were attained. The batch was extruded through a "spaghetti" die two times and then through a shaping die to form honeycomb monoliths of l-inch (2.54 cm) diameter having 200 square cells per square inch (about 30 cells per square centimeter). The "control" material was prepared by forming a slurry of 83.5 parts by weight distilled water, 15 parts al~nina monohydrate (DISPURAL, Remet Chem Corp.) and 1.5 parts acetic acid. 40 parts by weight of this slurry were then combined, in a mix muller, with a previously-made mixture of 100 parts by weight CATAPAL-B
alumina monohydrate, 6 parts METHOCEL, and 16 parts dis-tilled water. The batch was mixed and extruded to form a honeycomb as described above. In all cases, the honeycombs were fired at temperatures from 500-1200C for six hours, and their surface area (m2/g) measured by BET. For strength determination, rods of the batch material (approximately 1.3 cm in diameter) were also extruded and fired according to the same schedule, and the modulus of rupture (MOR) of the material was determined as described in U.S. Patent No.
4,631,267. The results are shown in Table 1 below.
.

Table 1 - Firing EX. lA EX. lB EX. lC Control Schedule SA MOR SA MOR SA MOR SA
(6 hours) (m2/g) (~si) (m2/g) (psi) (m2/g) (p~i) (m2 500C 221.9 666 226.7 1930217.1 9~2 190.0 750C 200.9 560 203.6 20~0197.51143 139.4 301000C 125.2 903 128.3 1540133.1 649 84.~
1100C 99.6 764 100.0 186094.7 716 6.1 1200C 18.3 1840 15.6 544014.8 2203 Example 2 Batches of alumina material with varying amounts of phosphate material addition (designated below as Examples ~)3~4~

2A-2F) and a control (100% alumina) were prepared by admixing the materials shown in Table 2 below and extruding the batched materials to form honeycombs. In examples 2A-2F, the indicated alumina and phosphate materials were combined in a mix muller with 6.0 parts by weight of METHOCEL and a sufficient amount of distilled water to provide plasticization. The "control" material was pre-pared and extruded as described in Example 1. The extruded honeycombs were then fired for 6 hours at 1000C and 1200C. For each example, Table 2 provides the alumina and phosphate batch ingredients as well as the composition and BET surface area of the fired material.

Table 2 Batch CompositionFired Composition (parts by weight) (weight %) ExamPle(NH4)2HP-o4 Al23 H2- Al AlPO4 2A 2 98 97.5 2.5 2B 5 95 93.8 6.2 - 20 2C 8 92 89.9 10.1 2D 16 84 79.3 20.7 2E 24 76 68.3 31.7 2F 40 60 44.5 ~5.5 Control 0 100 100 0 Surface Area Surface Area (1000C) (1200C) Example (m /g) (m /q) 2A 116.1 22.4 30 2B 127.0 29.2 2C 136.0 29.2 2D 129.4 16.3 2E 77.1 7.9 2F 0.6 0.3 35Control 86.8 6.1 ~1)(13~4~

Example 3 Batches of titania material with varying amounts of phosphate ~aterial addition (designated below as Examples s 3A-I) and a control (100% titania) were prepared by admixing the materials shown in Table 3 below, according to the procedure described in Example 1. In Examples 3A-I, the indicated titania and phosphate materials were combined in a mix muller with 6.0 parts by weight of METHOCEL and a sufficient amount of distilled water to provide plasticiza-tion. The "control" material was prepared in similar fashion with the exception that no phosphate material was added to the batch. In all cases, the batched material was dried at 110~C and then fired for 6 hours at 800C. For each example, Table 3 provides the titania and phosphate batch ingredients as well as the composition and BET
surface area of the fired material.

Table 3 Batch Composition Fired Composition Surface (parts by weight) (weight %) Area Example (NH4)2HP4 Ti2 P205 TiO2 (m2/q) 3A 60 4n 44.6 55.4 3.3 3B 40 60 26.4 73.6 12.4 25 3C 30 70 18.7 81.3 20.5 3D 20 80 11.8 88.2 25.9 3E 10 90 5.6 94.4 34.8 3F 8 92 4.5 95.5 35.3 3G 6 94 3.3 96.7 36.6 30 3H 4 96 2.1 97.9 36.3 3I 2 98 1.1 98.9 30.8 Control 0 100 100 0 3.0 Example 4 A suspension of 36 grams of zinc oxide in 1200 ml of distilled water was prepared. To this suspension was added 3~4~

108 ml of c3ncentrated hydrochloric acid. The resultant mixture was heated, with stirring, until all of the zinc oxide had dissolved. To this solution was then added 490.2 gra~s of titanium dioxide (Degussa Corp. P25) and the mixture was then neutralized with 108 ml of concentrated ammonium hydroxide, which caused a precipitation of the zinc oxide. The precipitated solution was centrifuged three times at 7000 rpm for 15 minutes, and the recovered solids material was transferred to an evaporating dish and heated at 110C until dry. The dried material was calcined for 3 hours at 300C and the calcined material then ball milled to a particle size finer than 100 mesh. The calcined and milled material was dry-mixed with 36 grams of METHOCEL binder and placed in a mix muller, into which was further charged a previously prepared solution of 37 grams of ammonium biphosphate dissolved in 75 ml of distilled water. Tetraisopropyl titanate, 199.8 grams, was then added to the muller, and the resulting batch was mixed in the presence of sufficient additional distilled water to plasticize the mixture. The plasticized material was extruded through a "spaghetti" die and then through a final die to form a honeycom~ shape having 300 square cells per square centimeter of frontal surface area. The extruded honeycombs were dried at 60C for 48-72 hours and then at 110C for 24 hours, after which they were fired at 500C
for 6 hours.

Example 5 A suspension of 30 grams of ferric oxide (Fe2O3) in 1200 ml of distilled water was prepared. To this suspen-sion was added 600 ml of concentrated hydrochloric acid.
The resultant mixture was heated, with stirring, until all of the ~erric oxide had dissolved. To this solution was then added 514.8 grams of titanium dioxide (Degussa Corp.
P25) and the mixture was then neutralized with 600 ml of 50% sodium hydroxide (aqueous), which caused a precipita-tion of the ferric oxide. The precipitated solution was centrifuged at 7000 rpm for 15 minutes. Centrifuging was repeated three times and the recovered solids material was transferred to an evaporating dish and heated at 110C
until dry. The dried material was calcined for 3 hours at 300C and the calcined material then ball milled to a particle size finer than 100 mesh. The calcined and milled material was dry-mixed with 36 grams of METHOCEL binder and placed into a mix muller, into which was further charged a previously prepared solution of 37 grams ammonium biphos-phate in 75 ml of distilled water. Tetraisopropyl titanate, 200 grams, was added to the muller and the resulting batch was mixed in the presence of sufficient additional dis-tilled water to plasticize the mixture. The plasticized material was extruded through a "spaghetti" die and then through a inal die to form a honeycomb shape having a~out 30 square cells per square centimeter of frontal surface area. The extruded honeycombs were dried at 60C for 48-72 hours and then at 110C for 24 hours, after which they were fired at 500C for 6 hours.

Example 6 A suspension of 36 grams of manganese dioxide in 1200 ml of distilled water was prepared. To this suspension was added 828 ml of concentrated hydrochloric acid. The resultant mixture was heated with stirring until all of the manganese dioxide had dissolved. To this solution was then - added 490.2 grams of titanium dioxide (Degussa Corp. P25) and the mixture then neutralized with 792 ml of concen-trated ammonium hydroxide, which caused a precipitation of - the manganese dioxide. The precipitated solution was centrifuged at 7000 rpm for lS minutes. Centrifuging was repeated three times and the recovered solids material was transferred to an evaporating dish and heated at 110C
until dry. The dried material was calcined for 3 hours at 300~C and the calcined material then ball milled to a X~ 94~

particle size finer than 100 mesh. The calcined and milled material was dry-mixed with 36 grams of METHOCEL binder and placed into a mix muller, into which was further charged a f previously prepared solution of 37 grams ammonium 5 biphosphate in 75 ml of distilled water. Tetraisopropyl titanate, 200 grams, was added to the muller and the resulting batch was mixed in the presence of sufficient additional distilled water to plasticize the mixture. The plasticized material was extruded through a "spaghetti" die 10 and then through a final die to form a honeycomb shape having 200 square cells per square inch of frontal surface area. The extruded honeycombs were dried at 60C for 48-72 hours and then at 110C for 24 hours, after which they were fired at 500C for 6 hours.

3~

Claims

1. A fired monolithic structure comprising (a) a porous metal oxide material, at least 50% by weight of which is alumina, titania, zirconia, or mixtures of these; and (b) P2O5 substantially dispersed throughout the porous metal oxide material in an amount of about 0.5-35% by weight, based on the total weight of P2O5 plus alumina, titania, and/or zirconia.

2. The monolith structure of claim 1 in which at least 80% by weight of the porous metal oxide material is alumina, titania, zirconia, or mixtures of these.

3. The monolithic structure of claim 1 in which substan-tially all the porous metal oxide material is alumina and in which the structure comprises about 1-10 weight percent P2O5, based on the total weight of alumina and P2O5.

4. The monolithic structure of claim 1 in which substan-tially all the porous metal oxide material is alumina, substantially all the P2O5 is in the form of AlPO4, and said AlPO4 constitutes about 4-23 weight percent of the structure.

5. The monolithic structure of claim 1 in which substan-tially all the porous metal oxide material is titania and in which the structure comprises about 1.5-15 weight percent P2O5, based on the total weight of titania and P2O5.

6. The monolithic structure of claim 1 in which substan-tially all the porous metal oxide material is titania, substantially all the P2O5 is in the form of 5TiO2-2P2O5, and said P2O5 compound constitutes about 5-12 weight percent of the structure.

7. The monolithic structure of claim 1 in which substan-tially all the porous metal oxide material is zirconia and in which the support comprises about 1-25 weight percent P2O5, based on the total weight of zirconia and P2O5.

8. The monolithic structure of claim 2 which is in the form of a catalyst support and which further comprises at least one catalytic metal or oxide thereof selected from the group consisting of transition metals and Group IIB
metals.

9. The monolithic catalyst support of claim 8 which comprises at least one catalytic metal or oxide thereof selected from the group consisting of zinc, molybdenum, vanadium, manganese, tungsten, copper, iron, platinum, and palladium.

10. The monolithic support of claim 9 in which the cata-lytic metal is about 3-20% by weight of the monolith.

11. The monolithic catalyst support of claim 8 which comprises about 3-20 weight percent of a catalytic metal selected from the group consisting of platinum, palladium, and mixtures of these.

12. The monolithic structure of claim 2 which is a fluid filter in the form of a honeycomb having about 4-370 cells per square centimeter of surface area.

13. A method of producing a fired monolithic structure comprising:
(a) admixing into a substantially homogeneous batch (i) a porous metal oxide material, at least 50%
by weight of which is alumina, titania, zirconia, a precursor therefor, or mixtures of these; and (ii) P2O5 or a precursor therefor in an amount sufficient to provide, after firing, about 0.5-35% by weight of P2O5 based on the total weight of P2O5 plus alumina, titania, and/or zirconia;
(b) forming said batch into a desired shape; and (c) firing the shape.

14. The method of claim 13 in which at least 80% by weight of the porous metal oxide material is alumina, titania, zirconia, or mixtures of these.

15. The method of claim 14 in which the P2O5 is provided in the form of phosphoric acid, dibasic ammonium phosphate, or aluminum dihydrogen phosphate.

16. The method of claim 13 in which substantially all the porous metal oxide material is alumina and in which suffi-cient P2O5 material is provided to generate about 1-10 weight percent P2O5 in the monolith following firing.

17. The method of claim 13 in which substantially all the porous metal oxide material is titania and in which suffi-cient P2O5 material is provided to generate about 1.5-15 weight percent P2O5 in the monolith following firing.

18. The method of claim 13 in which substantially all the porous metal oxide material is zirconia and in which sufficient P2O5 is provided to generate about 1-25 weight percent P2O5 in the monolith following firing.

19. The method of claim 14 which further comprises admixing into said batch about 3-20 weight percent, based on the total batch weight, of at least one catalytic metal or oxide thereof selected from the group consisting of transition metals and Group IIB metals, said catalytic metal or oxide thereof being in particulate form with an average primary particle size of up to about 20 microns.

20. The method of claim 19 in which said catalytic metal or oxide thereof has an average primary particle size of up to about 2.0 microns and is selected from the group con-sisting of zinc, vanadium, molybdenum, tungsten, palladium, platinum, iron, manganese, and copper.

21. The method of claim 19 in which said admixing step consists of admixing into said batch platinum, palladium, or a combination of these.

22. An improved monolithic catalyst support structure comprising a structural phase of a sintered ceramic material and a separate high surface area support phase of a porous metal oxide integral with the structural phase, wherein the porous metal oxide phase consists essentially of alumina, titania, zirconia, or mixtures of these and about 0.5-35% by weight, based on the total weight of the porous metal oxide phase, of P2O5 dispersed substantially throughout said phase.

23. The monolithic catalyst support of claim 22 in which said porous metal oxide phase consists essentially of alumina and about 1-10 weight percent P2O5.

24. The monolithic catalyst support of claim 22 in which said porous metal oxide phase consists essentially of titania and about 1.5-15 weight percent P2O5.

25. The improved monolithic catalyst support of claim 22 in which said porous metal oxide phase consists essentially of zirconia and about 1-25 weight percent P2O5.