A METHOD FOR PREPARING MIXED METAL OXIDES

Abstract: A process for preparing a mixed metal oxide, which process includes providing a metal carbonate-containing compound including a metal carbonate-containing anion with at least one cation; and at least a second cation; subjecting the metal carbonate-containing compound to ion exchange with the second cation to form a mixed metal-carbonate complex; and subjecting the complex to a heating step to form a mixed metal oxide.

Description: A METHOD FOR PREPARING MIXED METAL OXIDES The present invention relates to a process for preparing mixed metal oxides by cation-exchange from anionic carbonate-containing compounds. Mixed metal oxide phases known in the prior art have a wide variety of applications including use by themselves or as components in catalysts, corrosion resistant coatings, glazes, electrically conducting coatings, pigments, cosmetics, fillers, pharmaceuticals, plastics additives, alloy precursors and phosphors. Mixed metal oxides may consist of single phases, comprised of two or more metal species in chemical combination with oxygen, or of intimate mixtures of two or more phases. Industrial processes known in the prior art for preparation of mixed metal oxides include: (i) Solid state reaction between intimate mixtures of precursor oxide carbonate or other phases in definite proportions, generally at elevated temperatures, to produce a mixed metal oxide. This process often suffers from the necessity to employ severe reaction conditions and may require one or more cycles of grinding and heating to achieve complete reaction. (ϋ) Decomposition of precursor complexes containing mixtures of the metals in chemical combination or in solid solution in definite proportions. Known processes in the prior art have been of limited application as there has been a limited number of chemical combinations which are readily available for conversion to the oxide form. These can be produced by co-precipitation of an insoluble species, such as a hydroxide or carbonate, from aqueous or other solutions. Such procedures require that a set of conditions (eg pH, solvent) can be found to dissolve all the components before precipitation. Similarly, methods relying on solid solution formation in the precursor require similarity in chemical properties between the metal precursors. Sol-gel techniques have been successful in preparing mixed oxides. However, the cost of precursor species (generally alkoxides) can be extremely high. Prior art synthesis procedures for mixed oxide phases include the manufacture of the so-called β-aluminas such as, Ba0.6Al 2 0_ and La_0 3 .11A1 2 0 3 . These oxides are used as solid electrolytes and as stable support materials for high temperature catalytic reactions, and may be prepared utilizing the following methods: (i) Hydrolysis of mixed metal alkoxides, in which Ba metal and Al(iso-OPr)-, are stirred and refluxed at 80°C in 2-propanol under „ atmosphere, followed by hydrolysis to form mixed hydroxide. Calcination at high temperature results in the formation of Ba0.6Al_0 3 . This process, whilst useful, is limited by the expense of availability of starting materials. The process is also complex and difficult to control and thus not conducive to scale-up. (ii) Chemical co-precipitation, in which a mixture of La(OH)_ and Al(OH)_ is formed by co-precipitation from La(NO_)_ and Al(NO_) 3 . After calcining at 500°C, the powder with 1 wt% graphite was tabletted into a columnar shape and then fired to a higher temperature to obtain La_0,.11A1_0_ . Control of co-precipitation is, however, very difficult as the two species tend to disaggregate on crystallisation. Thus atomic mixing is very difficult to achieve. In a further example of known prior art methods partially and fully Y 2 0 3 -stabilised zirconias, which have applications as high performance ceramic, are usually prepared by chemical co-precipitation of hydroxides followed by calcination at high temperature. In practice, the distribution of the stabilising oxides depends on the detailed method of preparation. This process, whilst again useful, suffers from similar problems to other chemical co-precipitation processes. Binary oxides, such as those with spinel or perovskite structures,and which may be used in the ceramic and catalysis areas, are usually made by fusion or solid state reaction of intimately mixed powders chemical precipitation. Many of these methods afford products which are compositionally heterogeneous or have low surface areas, and hence are often unsuitable for use as catalysts. Accordingly it is an object of the present invention to overcome or at least alleviate one or more of the difficulties associated with the prior art. Accordingly, in a first aspect of the invention, there is provided a process for preparing a mixed metal oxide, which process includes providing a metal carbonate-containing compound including a metal carbonate-containing anion with at least one cation; and at least a second cation; subjecting the metal carbonate-containing compound to ion exchange with the second cation to form a mixed metal-carbonate complex; and subjecting the complex to a heating step to form a mixed metal oxide. The process according to the present invention is characterised in that production of mixed metal oxides requires only a simple process and the reaction conditons needed are relatively mild. For example, the complex is heated to significantly lower temperatures than required in the prior art. Further the precursor compounds used may be relatively inexpensive to produce. Moreover, the ratio of the metal and second cation can be varied quantitatively as required. Heating or calcining the mixed metal-carbonate complex may assist in decomposing any intermediate complex species formed, to form a mixed metal oxide. The metal carbonate-containing anion in the metal carbonate compound may be of any suitable type. Most preferably, the metal carbonate-containing anion may be - A - selected from anions of the general formula: [M(OH) y (C0 3 ) v (H 2 0) n X χ ] a - where M is selected from Be, Mg, Al, Ga, Sc, Y, rare earths, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Sn Cd, Pb or mixtures thereof; X is an anionic ligand; (typical anionic ligands include SCN, halide, phosphate, oxalate or an organic ligand) ; n, x, y, v and z are an integer or non-integer having a value between 0 and approximately 6 depending upon the metal, its oxidation state and its coordination requirements, with the proviso that v 0. The metal carbonate-containing anion in the metal carbonate containing compound may be obtained from any suitable source, such as, a pure inorganic salt or co-ordination complex, a simple metal or mixed metal oxide, a mineral ore or concentrate or spent catalysts, e.g. as industrial manufacturing or waste products. The cation in the metal carbonate compound may be of any suitable type. The cation may be selected from one or more of NH., an alkali metal, an alkaline earth, a substituted ammonium, phosphonium or arsonium, Zn, Mg, Tl or mixtures thereof. The second cation utilized in the ion exchange step may be of any suitable type. The second cation contains a metal which may be selected from one or more of Co, Ni, Cr, Fe, Ru, Pt, Pd, U, K, Al, Zn, Mn, Cu, Ag, Ba, Sr or Y, or rare earths, e.g. Ce, La. Any suitable form of this cation may be utilized. The second cation may be provided in the form of a hydroxide, oxide, carbonate, nitrate or acetate. The metal carbonate-containing compound may be utilized in any suitable form. The compound may be utilized alone, that is in the solid state, or in the form of a solution. Examples of metal-carbonate compounds that may be utilized in the process of the present invention include the following compositions: K 2 [Mg(C0 3 ) 2 ] (NH 4 )[A1(0H) 2 (C0 3 )] (NH 4 )[Ga(OH) 2 (C0 3 )] (NH 4 )[Cr(OH) 2 (C0 3 )] (NH 4 ) 3 [Zr(OH)(C0 3 ) 3 ] [N(C 2 H 5 ) 4 ] β [Ce(C0 3 ) 6 ] a 4 [U0 2 (C0 3 ) 2 ] (NH 4 [Co(1,2-ethylenediamine) 2 (C0 3 ) 2 ] (NH 4 ) 2 (guanidinium) 2 [Ce(C0 3 ) 5 (H 2 0)] κ 6 [Beθ 4 (C0 3 ) 6 ] Na g [Sc 2 (oxalato) 3 (C0 3 ) 3 ] Some or all of the exchangeable cations in the metal carbonate containing compound are exchanged with the second cation or mixture of cations in predetermined proportions. Accordingly in a preferred aspect of the present invention there is provided a process for preparing a mixed metal oxide, which process includes providing a metal carbonate-containing compound selected from K 2 [Mg(C0 3 ) 2 ] (NH 4 )[A1(0H) 2 (C0 3 )] (NH 4 )[Ga(OH) 2 (C0 3 )] (NH 4 )[Cr(OH) 2 (C0 3 )] (NH 4 ) 3 [Zr(OH)(C0 3 ) 3 ] [N(C 2 H 5 ) 4 ] 8 [Ce(C0 3 ) 6 ] Na 4 [U0 2 (C0 3 ) 2 ] (NH 4 tCo(1,2-ethylenediamine) 2 (C0 3 ) 2 ] (NH 4 ) 2 (guanidinium) 2 [Ce(C0 3 ) 5 (H 2 0)] K 6 [Be0 4 (C0 3 ) 6 ] Na g [Sc 2 (oxalato) 3 (C0 3 ) 3 ] (NH 4 ) 3 [Zr(OH)(C0 3 ) 3 ]; and a second cation selected from salts of Barium Yttrium, Lanthanum and Nickel; subjecting the metal-carbonate containing compound to ion exchange with the cation to form a mixed metal-carbonate complex; and subjecting the complex to a heating step to form a mixed metal oxide. Most preferably, the metal carbonate-containing compound is selected from; K 2 [Mg(C0 3 ) 2 ] (NH 4 )[A1(0H)(C0 3 ) 3 ] or (NH 4 )[Zr(OH)(C0 3 ) 3 ] The ion exchange reaction may be performed in any suitable solvent, such as water or methanol and at a suitable temperature. The temperature should be high enough to complete the exchange reaction, but low enough to deter any decomposition of the carbonate complex. Temperatures in the range of approximately 2°C to 100°C are preferred. However temperatures in the range of approximately 5°C to 40°C have been found to be most suitable. The reaction product may then be heated at elevated temperatures to decompose any intermediate complex. Most suitably the heating may continue for approximately 4 to 48 hours. Temperatures in the range of approximately 25°C to 1600°C, depending upon the combination of metals selected and end use proposed. Preferably approximately 400°C to 1200°C may be used. Most preferably the temperature may be raised progressively to reach a maximum temperature of approximately 1200°C. Materials which stabilise the metal carbonate in solution, such as inorganic or organic ligands, ammonium carbonate, NH_ or CO ? may optionally be added. The pH or acidity of the solution should be such as to minimise any solvolysis reaction or displacement of the coordinated carbonate. The degree of ion exchange may be controlled by choice of a time sufficient for completion of the reaction or by repetitive exchange, or by an appropriate choice of the concentrations and ratios of the reactants. In particular, the composition of the resulting mixed oxide may be controlled by full or partial ion exchange of initial cation with the second cation in the appropriate proportions. The ion exchange product may be anhydrous or hydrated or mixed hydroxide, carbonate, hydroxycarbonate, or oxo complexes or a combination thereof. These, complexes may be converted into the anhydrous mixed oxide by an appropriate thermal treatment. The ion exchange reaction may be performed in any suitable vessel, either in the slurry phase, or in solution. Alternatively, the metal-carbonate component may be coated onto or impregnated in any suitable porous or non-porous substrate and the ion exchange reaction performed subsequently. Mixed oxides prepared by the process of the present invention may contain two or more different kinds of cations at varying proportions and may be a single phase chemical compound, a solid solution, or a mixture of compounds. Typical mixed metal oxides may be selected from β aluminas, such as Ba0.6Al 2 0 3 , La_0 3 .11A1 2 0 3 , Y 2 0 3 stabilized Zirconia, Ni supported on Zirconia and Ni supported on Alumina and binary oxides such as BaZr0 3 . The β aluminas may exhibit increased surface areas. The Yttrium-stablized zirconia may exhibit an improved distribution of the stabilizing oxide. The binary oxides may exhibit improved compositional homogeneity and increased surface area. The mixed metal oxides according to the present invention may function as supported metal catalyst precursors. Supported metal catalysts comprise an active metallic phase dispersed over a support material. The primary role of the support is to achieve a high surface area active metal phase and to maintain this high area by stabilising the catalyst against agglomeration and coalescence. The support also acts to improve the poison resistance of the catalyst and its cost. Most commonly (but not exclusively), support materials are acidic, basic, neutral or amphoteric oxides (examples of common supports: alumina, silica, silica-alumina, titania, zirconia, magnesia (MgAlO.). For high temperature applications stabilised aluminas (e.g. Ba0.6Al_0_, La 2 0 3 .IlAl 2 0 3 ) are often used. Supported metals are synthesised in the prior art by producing a reducible metal/support precursor (reducible metals: Co, Fe, Ni, Cu, Ag, Au, Ru, Rh, Pd, Re, Os, Ir, Pt) which is subsequently converted to the active catalyst by heat treatment in a reducing atmosphere (containing hydrogen or carbon monoxide) which produces the active metallic phase. Catalyst precursors are commonly produced by impregnating the support with a metal compound, co-precipitation of support and metal compound, or ion exchange of a metal compound with the support. The present invention provides a new method for obtaining a supported metal catalyst precursor by exchange of reducible metal ions with a metal-carbonate containing compound. In this aspect, the metal-carbonate containing compound functions as a support precursor. Subsequent heat treatment decomposes the carbonate compound to form an oxide support. The active supported metal catalyst is produced by heat treatment of the obtained precursor in a reducing atmosphere. Accordingly, in a further aspect of the present invention there is provided a process for preparing a supported metal catalyst which process includes providing a metal carbonate-containing compound including a metal carbonate-containing anion with at least one cation; and at least a second cation; subjecting the metal carbonate-containing compound to ion exchange with the second cation to form a mixed metal-carbonate complex; subjecting the complex to a first heating step to form a mixed metal oxide; and subjecting the mixed metal oxide to a second heating step under reducing conditions to form a supported metal catalyst. The temperature range and composition of the required reducing conditions is determined by the type of metal and type of precursor species. Temperatures in the range of from approximately 300°C to 1000°C may be used. The second heating step may be conducted in a reducing atmosphere. The reducing atmosphere may contain hydrogen or carbon monoxide. For example, mixed NiO/Zr0 2 and NiO/Al 2 0 3 phases are converted to supported Ni/Zr0 2 and Ni/Al 2 0 3 catalysts by heat treatment in an atmosphere containing hydrogen in the temperature range of from approximately 400°C to 600°C. In the following description, the invention will be more fully described with reference to the accompanying examples. It should be understood, however, that the following examples are illustrative only, and should not be taken in any way as a restriction on the generality of the invention described above. EXAMPLE 1 Ba(OH) 2 .8H 2 0 (1.02 g) was added to a slurry of NH 4 Al(OH) 2 C0 3 nH 2 0 (7.5 g, 26.5 wt% A1 2 0 3 ) in H 2 0 (40 ml) with vigorous stirring under nitrogen at 21°C. After stirring the mixture for 3 days the solid was removed by filtration and washed with water (3 x 100 ml) . The isolated solid sample (2.3 g) was then calcined in air at 400°C for 16 hours, 600°C for 4 hours and then 800°C for 2 hours. Further calcination at (i) 1000°C, (ii) 1100 β C, (iii) 1200°C, (iv) 1300°C, (v) 1400°C gave the surface areas of 125, 74, 20, 10 and 10m 2/g respectively. The presence of Ba0.6Al ? 0_ as the only crystalline phase was confirmed by powder XRD, by comparison with JCPDS Data File (#26-135) . EXAMPLE 2 PREPARATION OF 5 wt% BaO/Al O The procedure of Example 1 was followed, except that 0.26 g of Ba(OH) 2 .8H 2 0 and 9.lg ( H 4 )A1(0H) 2 C0 3 .nH 2 0 (26.4 wt% A1 2 0 3 ) was used, to afford 2.4 g of product. Analysis by atomic absorption spectrophotometry showed the presence of 4.7 wt% BaO. The BET surface areas of the product, after heating to 1000°C, 1100°C, 1200°C, 1300°C aanndd 1 1440000°°CC,, were 123, 108, 23, 10 and 10m 2 /g respectively. EXAMPLE 3 PREPARATION OF 10 wt BaO/Al-O. ^ 2-3 The procedure of Example 1 was followed, except that 0.52 g of Ba(OH) 2 .8H 2 0 and 8.3 g (NH 4 )A1(OH) 2 C0 3 .nH 2 0 (26.4 wt% A1_0 3 ) was used, to afford 2.3 g of product, containing 10.0 wt% BaO. The BET surface areas of the product, after heating to 1000°C, 1100°C, 1200°C, 1300°C aanndd 11440000°°CC,, were 178, 134 30, 10 and 10m 2 /g respectively, EXAMPLE 4 PREPARATION OF 15 wt% Ba0/A1 2 Q 3 The procedure of Example 1 was followed, except that 0.79 g of Ba(OH) 2 .8H 2 0 and 8.2 g (NH 4 )A1(0H) 2 C0 3 .nH 2 0 (26.4 wt% Al 2_0~3)' was used, to afford 2.4 g of product, containing 15.3 wt% BaO. The BET surface areas of the product, after heating to 1000°C, 1100°C, 1200°C, 1300°C and 1400°C, were 143, 104, 12, 11 and 10m 2 /g respectively. EXAMPLE 5 PREPARATION OF La^ . HAl^ The procedure of Example 1 was followed, except that La(N0 3 ) 3 .6H 2 0 (1.70 g) in ethanol (20 ml), was Stirred with ( H 4 )A1(0H) 2 C0 3 .nH 2 0 (8.4 g, 26.4 wt% A1_0 3 ) to afford a white powder (2.6 g) . The presence of La 2 0 3 .llAl 2 0 3 as the only crystalline phase in the heated product was determined by powder XRD, by comparison with the JCPDS Powder File, #28-502. The BET surface areas of the product, after heating to 1000°C, 1200°C and 1400°C, were 33, 21 and 10m 2 /g respectively. EXAMPLE 6 PREPARATION OF 11 wt% La 2 Q /Al O The procedure of Example 5 was followed, except that 0.76 g of La(N0 3 ) 3 .6H 2 0 and 8.5 g (NH 4 )A1(OH) 2 C0 3 .nH 2 0 (26.4 wt% A1 2 0 3 ) was used, to afford 2.3 g of product (11 wt La ° ^y atom i c absorption spectrophotometry). The BET surface areas of the product, after heating to 1000°C, 1200°C and 1400°C, were 92, 28 and 10m 2 /g respectively. EXAMPLE 7 PREPARATION OF MαAl 0 4 Mg(N0 3 ) 2 .6H 2 0 (4.8 g) was added to a slurry of (NH 4 )Al(0H) 2 C0 3 nH 2 0 (4.8 g, 26.4 wt% Al^) in ethanol (20 ml) under nitrogen at 21°C and the slurry vigorously stirred for 20 hours. The resultant white solid was filtered and washed with ethanol (2 x 100 ml). To ensure complete exchange the treatment with Mg N0 3 > 2 .6H 2 0 solution was repeated 3 times on the solid residue. A comparison of the IR spectra of (NH 4 )Al(OH) 2 CO_nH 2 0 with the product indicated full ion-exchange of the NH 4 + had occurred after the 4th exchange step. The wet solid was dried in air for 1 day and then calcined in air at 400°C for 16 hours, 600°C for 4 hours, and 800 β C for 4 hours. The XRD trace of the product (1.8 g) indicated the formation of MgAl 2 0 4 . After calcining the solid further at 1000°C for 2 hours, the BEt surface 2 area of the solid was 102m /g. Comparison with JCPDS Powder Data File (#21-1152) confirmed the presence of M ALO, as the only crystalline product. EXAMPLE 8 PREPARATION OF NiAl 2-—O4. (NH 4 )Al(OH) 2 C0 3 .nH 2 0 (1.75 g, 26.4 wt% Al^) was added to a solution of i(N0 3 ) 2 .6H 2 0 (42.4 g) in methanol (50 ml) and the slurry vigorously stirred in a sealed conical flask at 21 β C for 30 hours. The resultant solid was filtered, washed with water (3 x 50 ml) and dried in air for 1 day. A comparison of the IR spectra of (NH 4 )Al(0H) 2 C0 3 .nH 2 0 and the product indicated full ion-exchange of the NH had occurred. The green product (0.7 g) was calcined in air at 400°C for 16 hours, 600°C for 4 hours, and 850°C for 2 hours. A XRD powder pattern confirmed that NiAl_0 4 was the only crystalline phase, by comparison with the JCPDS Powder File (#10-330). EXAMPLE 9 SUPPORTED Ni/A1 2 Q CATALYST A supported i/Al 2 0 3 catalyst was prepared by the procedure of Example 8, except that 7.63 g Ni (N0 3 ) 2 .6H 2 0 in 200 ml MeOH was used. The isolated solid sample was then calcined in air at 600°C, to give a green product (0.4 g, 6 wt% NiO by atomic absorption spectrophotometry) . Temperature programmed reduction (from 20°C to 950°C at 10°C C/min) NiO/Al 0 3 in a stream of flowing 3% H„/N_ resulted in quantitative reduction of the NiO to Ni metal, with the maximum reduction rate observed at about 675°C. EXAMPLE 10 PREPARATION OF Y^-STABILISED ZIRCONIA To a solution of Y(N0 3 ) 3 -6H 2 0 (0.23 g) in methanol (50 ml), (NH 4 ) 3 Zr(OH) (C0 3 ) 3 (3.67 g, 32.5 wt % ZrO ? ) was added and stirred under N 2 at 20°C for 48 hours. The solid was separated by filtration, washed with methanol (3 x 100 ml) and dried in vacuo at room temperature. The material was calcined at 400°C in air for 4 hours and then 800°C for 4 hours to afford 1.2 g of product. A XRD powder pattern demonstrated the formation of tetragonal ZrO_ as the only crystalline product, by comparison with the JCPDS Powder Diffraction File, #17-923. EXAMPLE 11 PREPARATION OF BaZrQ 3 To a solution of BaBr 2 .2H 2 0 (6.7 g) in methanol (50 ml), (NH 4 ) 3 Zr(OH)(C0 3 ) 3 (3.78 g, 32.5 wt% Zr0 2 was added and stirred under N 2 at 20°C for 48 hours. The solid was separated and the excess BaBr_ was washed away with methanol (3 x 100 ml), followed by drying in vacuo at room temperature. The residue was calcined at 400°C in air for 4 hours then 800°C for 16 hours to afford 2.5 g of product. The XRD trace indicated the formation of BaZr0 3 as the only crystalline phase, by comparison with the JCPDS Powder Diffraction File, #6-399. EXAMPLE 12 AN ALTERNATIVE PREPARATION OF BaZrO, '3 A solution of Ba(0H)2.8H 2 0 (3.15 g) in water (50 ml) was added to a slurry of (NH 4 ) 3 Zr(0H) (C0 3 ) 3 (3.78 g, 32.5 wt% Zr0 2 ) in water (20 ml) with vigorous stirring under 2 at 20°C. The exchange reaction was allowed to continue for 16 hours. The precipitate was washed with water (3 x 100 ml), followed by drying in air at room temperature. The product was then calcined at 800°C for 16 hours. The XRD trace indicated the formation of BaZrO_ as the only crystalline phase. EXAMPLE 13 PREPARATION OF SUPPORTED NiO/Zr0 2 A solution of Ni(N0 3 ) 2 .6H 2 0 (17.5 g) in methanol (80 ml) was added to a slurry of (NH 4 ).,Zr(OH)(C0 3 ) 3 (7.56 g, 32.5 wt% Zr0 2 ) n methanol (50 ml) with vigorous stirring at 20°C. The exchange reaction was allowed to continue for 48 hours. The solid was separated and the excess of Ni(N0 3 ) 2 was washed away with methanol (3 x 100 ml) followed by drying in vacuo at room temperature. The residue was calcined in air at 400°C for 4 hours then at 1000°C for 4 hours, to afford 4.5 g of product, containing 45 wt% NiO as determined by atomic absorption spectrophotometry. A XRD powder pattern shows the presence of a mixture of NiO and tetragonal ZrO ? , by comparison with the JCPDS Powder Diffraction Files, #22-1189 and #17-923. Temperature programmed reduction (from 20°C to 950°C at 10°C/min) NiO/Zr0 2 in a stream of flowing 3% H 2 /N 2 resulted in quantitative reduction of the NiO to Ni metal, with the maximum reduction rate observed at about 480°C. Finally, it is to be understood that various other modifications and/or alterations may be made without departing from the spirit of the invention as outlined herein.

Claims: Claims 1. A process for preparing a mixed metal oxide, which process includes providing a metal carbonate-containing compound including a metal carbonate-containing anion with at least one cation; and at least a second cation; subjecting the metal carbonate-containing compound to ion exchange with the second cation to form a mixed metal-carbonate complex; and subjecting the complex to a heating step to form a mixed metal oxide. 2. A process according to claim 1, wherein the metal carbonate-containing anion is selected from anions having the formula [M(0H) y (C0 3 ) v (H 2 0) n X χ ] a - where M is selected from Be, Mg, Al, Ga, Sc, Y, rare earths, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Sn Cd, Pb or mixtures thereof; X is an anionic ligand; n, x, y, v and z are an integer or non-integer having a value between 0 and approximately 6 depending upon the metal, its oxidation state and its coordination requirements, with the proviso that v ≠ 0 . 3. A process according to claim 2, wherein the cation in the metal carbonate compound is selected from one or more of NH 4 , an alkali metal, an alkaline earth, a substituted ammonium, phosphonium or arsonium, Zn, Mg, Tl or mixtures thereof. 4. A process according to claim 1, wherein the second cation is selected from one or more of Co, Ni, Cr, Fe, Ru, Pt, Pd, U, K, Al, Zn, Mn, Cu, Ag, Ba, Sr or Y, or rare earths. 5. A process according to claim 4, wherein the second cation is provided in the form of a hydroxide, oxide, carbonate, nitrate or acetate. 6. A process according to claim 3, wherein the metal carbonate-containing compound is selected from K 2 [Mg(C0 3 ) 2 ] (NH 4 )[A1(0H) 2 (C0 3 )] (NH 4 )[Ga(OH) 2 (C0 3 )] (NH 4 )[Cr(OH) 2 (C0 3 )] (NH 4 ) 3 [Zr(0H)(C0 3 ) 3 ] [N(C 2 H 5 ) 4 ] 8 [Ce(C0 3 ) 6 ] Na 4 [U0 2 (C0 3 ) 2 3 (NH 4 [Co(1,2-ethylenediamine) 2 (C0 3 ) 2 ] (NH 4 ) 2 (guanidinium) 2 [Ce(C0 3 ) 5 (H 2 0)] K g [Be0 4 (C0 3 )g] Na g [Sc 2 (oxalato) 3 (C0 3 ) 3 ] . 7. A process according to claim 1, which process includes providing a metal carbonate-containing compound selected from K 2 [Mg(C0 3 ) 2 ] (NH 4 )[A1(0H) 2 (C0 3 )] (NH 4 )[Ga(OH) 2 (C0 3 )] (NH 4 )[Cr(OH) 2 (C0 3 )] (NH 4 ) 3 [Zr(0H)(C0 3 ) 3 l [N(C 2 H 5 ) 4 ] 8 [Ce(C0 3 ) 6 ] Na 4 [U0 2 (C0 3 ) 2 ] (NH 4 [Co ( 1 , 2-ethylenediamine) 2 (C0 3 ) 2 ] (NH 4 ) 2 (guanidinium) 2 [Ce(C0 3 ) 5 (H 2 0)] K 6 [Be0 4 (C0 3 ) 6 ] Na g [Sc 2 (oxalato) 3 (C0 3 ) 3 ] (NH 4 ) 3 [Zr(OH)(C0 3 ) 3 ]; and a second cation selected from salts of Barium Yttrium, Lanthanum and Nickel; subjecting the metal-carbonate containing compound to ion exchange with the cation to form a mixed metal-carbonate complex; and subjecting the complex to a heating step to form a mixed metal oxide. 8. A process according to claim 7, wherein the metal- containing compound is selected from K 2 [Mg(C0 3 ) 2 ] (NH 4 )[A1(0H)(C0 3 ) 3 ] or (NH 4 )[Zr(OH)(C0 3 ) 3 ]. 9. A process according to claim 1, wherein the ion exchange reaction is conducted at a temperature in the range of from approximately 2°C to 100°C. 10. A process according to claim 9, wherein the complex formed is heated to a temperature in the range of 25°C to 1600°C and heating continues for approximately 4 to 48 hours. 11. A mixed metal oxide, whenever prepared by a process according to any one of the preceding claims. 12. A mixed metal oxide according to claim 11, which is selected from β-aluminas, Y 2 ° 3 ' stabilized zirconia, and binary oxides. 13. A process for preparing a supported metal catalyst, which process includes providing a metal carbonate-containing compound including a metal carbonate-containing anion with at least one cation; and at least a second cation; subjecting the metal carbonate-containing compound to ion exchange with the second cation to form a mixed metal-carbonate complex; subjecting the complex to a first heating step to form a mixed metal oxide; and subjecting the mixed metal oxide to a second heating step under reducing conditions to form a supported metal catalyst. 14. A process according to claim 13, wherein the second heating step is conducted in a reducing atmosphere at a temperature in the range of approximately 300°C to 1000°C. 15. A supported metal catalyst wherever prepared by a process according to claims 13 or 14. 16. A supported metal catalyst according to claim 15, selected from nickel supported on zirconia and nickel supported on alumina. 17. A process according to claim 1, substantially as hereinbefore described with reference to any one of the examples.

Inventors: FOGER KARL, HOANG MANH, TURNEY TERENCE WILLIAM, FOGER, KARL, HOANG, MANH, TURNEY, TERENCE, WILLIAM
Applicants: COMMW SCIENT IND RES ORG, FOGER KARL, HOANG MANH, TURNEY TERENCE WILLIAM, COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH OR
Application year: 1993
Main classification: C01G1
IPC codes: B01J23, B01J37, C01B13, C01F5, C01F7, C01F17, C01G25, C01G53