WO2008116081A2

WO2008116081A2 - Anderson-type heteropolyanions

Info

Publication number: WO2008116081A2
Application number: PCT/US2008/057683
Authority: WO
Inventors: Paul O'connor; Dennis Stamires; William Jones; Michael F. Brady
Original assignee: Albemarle Netherlands B.V.
Priority date: 2007-03-21
Filing date: 2008-03-20
Publication date: 2008-09-25
Also published as: WO2008116081A3

Abstract

The preparation of Anderson-type heteropolyanions that are more economical and environmentally attractive, as well as more suitable for industrial, large-scale production, is disclosed generally comprising the steps of providing at least one solid source of a polyvalent metal Me, heat treating the at least one solid source of a polyvalent metal Me, and contacting the heat treated polyvalent metal Me with an aqueous solution of at least one source of a transition metal TM, wherein the polyvalent metal Me is not the same as the transition metal TM, and wherein the atomic ratio TM:Me is at least about 2.5.

Description

ANDERSON-TYPE HETEROPQL YANIONS

[0001] Anderson-type heteropolyanions are known from the literature and are represented by the general formula [H_xXM₆O₂₄]^11" (with X being a heteroatom and M being Mo or W), and are named after Anderson who suggested a structure for such anions in 1937 (Anderson, J.S. (1937), Nature (London), 150, 850). Anderson-type heteropolyanions are classified into the A-type (x=0) and the B-type (x=6) by the number of attached protons, although some polyanions with x other than 0 or 6 have also been reported.

[0002] Anderson-type heteropolyanions can be prepared according to the methods described by Nomiya et.al. (Nomiya, K., Takahashi, T., Shirai, T. & Miwa, M. (1987), Polyhedron, 6, 213-218). These methods relate to the preparation of A-type and B-type Anderson-type heteropolyanions wherein M = Mo or W, and X is a divalent or trivalent metal ion such as Zn(II) or Al(III). The methods comprise in general preparing molybdo- or tungsto- polyanions by adding an aqueous solution of metal sulfates or alums to a boiling aqueous solution of ammonium heptamolybdate hydrate, further evaporating on a steam-bath, followed by filtering the hot solution and cooling.

[0003] The present invention provides a method for the preparation of Anderson-type heteropolyanions that is more economical and environmentally attractive, as well as more suitable for industrial, large-scale production, wherein the use of boiling solutions are avoided and the use of soluble salts is optional.

[0004] Also provided are methods for the production of new Anderson-type heteropolyanion compounds that consist of an Anderson-type heteropolyanion in a matrix, such as an inorganic oxide matrix like an alumina source (e.g. gibbsite, boehmite etc), nickel oxide, and the like, which method provides Anderson-type heteropolyanions with diverse and adaptable properties.

[0005] It has surprisingly been found that the method according to the invention is suitable for the production of many different Anderson-type heteropolyanions, containing for example as the heteroatom, and W and Mo as the transition metal. Therefore the method of the invention enables the production of various, diverse Anderson-type heteropolyanions, incorporating divalent, trivalent metals (or metals of higher valency) and transition metals (for example W and Mo) of choice. [0006] Also, the method of the invention makes possible the use of an alumina source (such as gibbsite, boehmite), which enables the preparation of a wide range of end products, both containing alumina and products that are alumina-free, resulting in a great range of possible Anderson-type heteropolyanions with great versatility.

[0007] The method of the invention generally comprises the steps of providing at least one solid source of a polyvalent metal Me; heat treating the at least one solid source of a polyvalent metal Me, and contacting the heat treated polyvalent metal Me with an aqueous solution of at least one source of a transition metal TM, wherein the polyvalent metal Me is not the same as the transition metal TM, and wherein the atomic ratio TM:Me is at least about 2.5.

[0008] In the disclosed method, in order to produce an Anderson-type heteropolyanion, the atomic ratio of transition metal TM to the polyvalent metal Me (for example, the atomic ratio of W:Zn or Mo:Ni or W:(Zn+Ni)) in the reaction mixture should at least be 2.5. However, higher ratios may be preferred, dependent on the identity of the transition metals present. Suitably, the atomic ratio TM: {M(II)+M(III)}, where M(II) is a divalent metal and M(III) is a trivalent metal, is at least 3.0, preferably at least 5.0, more preferably at least 8.8, even more preferably at least 12.0, even more preferably at least 15, more preferably at least 17.5. Even higher ratios such as at least 25 and even at least 35 are also suitable.

[0009] The lower limit of the ratio is determined by the nature of the transition metal and polyvalent metal used. At low ratios the X-ray diffraction patterns indicate unidentified reflections, not belonging to the phases containing the Anderson-type heteropolyanions. According to the X-ray diffraction patterns of the products produced, the higher the atomic ratio transition metal to divalent metal + trivalent metal (TM: (M(II)+M(III)}), the less of this unidentified phase is present. At higher ratios, for example at or above 8.8 or at or above 17.5, these unidentified peaks dimmish and in many cases finally disappear from the spectra. The exact situation depends upon the choice of the divalent, trivalent and transition metal. While not being bound by any theory, it is therefore believed that at higher ratios, for example at about 17.5 or even about 35, a more pure product is obtained. It is therefore generally preferred to use a relatively high atomic ratio of TM: {M(II)+M(III)} of at least 8 or more preferred at least 10, but this value will depend upon the choice of the divalent, trivalent and transition metals. [0010] The method of the invention may include additional steps to the steps indicated above. For instance, there may be an intermediate drying step, a shaping step, a milling step, an additional aging step, an additional calcination step, or washing and filtering steps. Moreover, additional compounds like acids, bases, or metal compounds can be added where appropriate. These steps will be described in more detail below.

[0011] The first step in the method of the invention, entails providing at least one source of a polyvalent metal Me. In many cases this polyvalent metal is a divalent metal and/or a trivalent metal, hi the present context, the term "a source of a divalent metal and/or a trivalent metal" is used to describe a compound containing a divalent metal M(II), or a trivalent metal M(III), or both. Examples thereof are given below. Combinations of sources of divalent and/or trivalent metals may also be used.

[0012] As the skilled person will appreciate, some metals can be present in a divalent and a trivalent state. Such metals can be used in both forms in the present invention. It is therefore possible to prepare a product containing a mixture of Anderson-type heteropolyanions with Fe(II) and Fe(III) as the hetero atoms.

[0013] The at least one source of a divalent metal and/or a trivalent metal can comprise one or more of (i) a divalent metal M(II) selected from the group consisting of Zn(II), Fe(II), Co(II), Cu(II), Ni(II), Mn(II), Ca(II), Ba(II), Sr(II), Mg(II), and mixtures thereof, and/or (ii) a trivalent metal M(III) selected from the group consisting of Al(III), Ga(III), Fe(III), Cr(III), Co(III), Rh(III)₅ Ce(III), and mixtures thereof.

[0014] The source of a divalent and/or trivalent metal may have been doped with other metals, such as Al, Ga, Cr, Fe, V, B, In, Nb, W, Mo, Ta, Pt, Pd, Rh, Zr, Ti, P, Si or mixtures thereof. The term "doped" is used in this context in connection with a source of a divalent and/or trivalent metal to describe such a source containing less than 20 wt % of the metal with which it is doped. This doped source of a divalent and/or trivalent metal can be obtained by any method known in the art, for instance co-precipitation, thermal or hydrothermal treatment of a source of a divalent and/or trivalent metal with a compound of the desired metal.

[0015] In its broadest description the at least one source of a divalent metal and/or a trivalent metal can be a soluble or insoluble compound. [0016] An insoluble source of a divalent metal and/or a trivalent metal can be chosen from the oxide, hydroxide, carbonate, oxycarbonate, or hydroxy carbonate of a polyvalent metal, or mixtures thereof, for example, zinc or nickel carbonate, or a mixture thereof. In case a single insoluble source of a divalent metal and/or a trivalent metal is used, this source can be used in the heat treating step as such, that is in dry, solid form. The single insoluble source of a divalent metal and/or a trivalent metal can also be slurried in water, providing a slurry of the source of a divalent metal and/or a trivalent metal.

[0017] In case more than one insoluble source of a divalent metal and/or a trivalent metal is used, it is still possible to use the insoluble sources in dry, solid form, however it is preferred to provide an aqueous slurry of the more than one insoluble source of a divalent metal and/or a trivalent metal, to ensure a sufficient blending of the compounds.

[0018] The at least one source of a divalent metal and/or trivalent metal can also be a soluble compound, for example a salt such as a nitrate, formate, acetate, chloride or oxalate of a polyvalent metal. This soluble source of a divalent metal and/or a trivalent metal will first be solubilized in water, whereafter it is precipitated by increasing the pH of the solution. The pH can be increased by adding a basic compound, for example sodium carbonate, a sodium hydroxide solution, ammonium hydroxide or urea, to the solution of the soluble source of a divalent metal and/or a trivalent metal. The suitable pH range will depend upon the kind of metals and other components present in the solution, and is sufficiently high to ensure precipitation of the metals and components present, but not too high in order to avoid re-dissolving the precipitate. The pH of the solution containing the source of a divalent metal and/or a trivalent metal to be precipitated will in most cases be increased to a value of about 4 to about 9. Higher pH values can be used, if suitable. The temperature of the solution during precipitation is preferably about ambient temperature to about 100⁰C.

[0019] It is also possible to combine in the first step at least one soluble and at least one insoluble source of a divalent metal and/or a trivalent metal. In this case one or more soluble sources of a divalent metal and/or a trivalent metal are precipitated as indicated above, and mixed or slurried with the one or more insoluble sources of a divalent metal and/or a trivalent metal.

[0020] In one of the embodiments of the invention an aluminum source is present in the first step. That is, an aluminum source can be mixed with the at least one insoluble source of a divalent metal and/or a trivalent metal in dry form, or can be present in the slurry of the at least one source of a divalent metal and/or a trivalent metal, by adding such aluminum source to the slurry. The aluminum source is preferably slurried with the at least one insoluble source of a divalent metal and/or a trivalent metal (optionally after precipitation as described above), as this results in a better blend of the aluminum source and the at least one insoluble source of a divalent metal and/or a trivalent metal.

[0021] Examples of the water-insoluble aluminum source that can be used in the process of the invention includes aluminum oxides and hydroxides, such as gel alumina, boehmite, pseudoboehmite (either peptized or not), aluminum trihydrates, thermally treated aluminum trihydrates, and mixtures thereof. Examples of aluminum trihydrates are crystalline aluminum trihydrate (ATH), for example gibbsites provided by Reynolds Aluminum Company RH-20a or JM Huber Micrala grades, BOC (Bauxite Ore Concentrate), bayerite, and nordstrandite. BOC is the cheapest water-insoluble aluminum source.

[0022] The water-insoluble aluminum source preferably has a small particle size, preferably below 10 microns.

[0023] Calcined aluminum trihydrate is readily obtained by thermally treating aluminum trihydrate (gibbsite) at a temperature ranging from 100° to 1,000⁰C for 15 minutes to 24 hours. In any event, the calcining temperature and the time for obtaining calcined aluminum trihydrate should be sufficient to cause a measurable increase of the surface area compared to the surface area of the gibbsite as produced by the Bayer process, which is generally between 30 and 50 m²/g. Within the context of this invention flash calcined alumina (e.g. Alcoa CP® alumina) is also considered to be a thermally treated form of aluminum trihydrate. Flash calcined alumina is obtained by treating aluminum trihydrate at temperatures between 800° and 1,00O⁰C for very short periods of time in special industrial equipment.

[0024] The water-insoluble aluminum source may have been doped with one or more metal compounds, for instance rare earth metals or transition metals. Examples are compounds of, for instance, Ce, La, V, Mg, Ni, Mo, W, Mn, Fe, Nb, Ga, Si, P, Bi, B, Ti, Zr, Cr, Zn, Cu, Co, and combinations thereof, preferably in amounts between 1 and 40 wt%. This doped water-insoluble aluminum source can be obtained by any method known in the art, for instance thermal or hydrothermal treatment of a water-insoluble aluminum source with a compound of the desired metal. Preferably oxides, hydroxides, and carbonates of these doping metals are used, but also nitrates, chlorides, sulfates, phosphates, acetates, and oxalates can be used. When a doped water-insoluble aluminum source is used as a starting material for the preparation of compositions comprising an Anderson-type heteropolyanion and aluminum oxide or hydroxide, doped aluminum oxide or hydroxide (in a controlled amount) will be present in the final product.

[0025] The first step of the process can be conducted in either batch or continuous mode, optionally in a continuous multi-step operation. The process can also be conducted partly batch- wise and partly continuously.

[0026] The source of a divalent metal and/or a trivalent metal and the optional water- insoluble aluminum source are added to a reactor and milled or preferably slurried in water. The reactor can be heated by any heating source such as a furnace, microwave, infrared sources, heating jackets (either electrical or with a heating fluid), lamps, etc. The reactor may be equipped with stirrers, baffles, etc., to ensure homogeneous mixing of the reactants.

[0027] In the embodiments of the invention in which an aluminum source is used, the aqueous suspension in the reactor can be obtained by combining water, the at least one source of a divalent metal and/or a trivalent metal, and the water-insoluble aluminum source either per se, as slurries, or combinations thereof. Additionally, in the case of a water-soluble source of a divalent metal and/or a trivalent metal, it can be added as a solution to be precipitated. Any sequence of addition can be used: the source of a divalent metal and/or a trivalent metal can be added to a slurry of the water-insoluble aluminum source, the water- insoluble aluminum source can be added to a slurry or solution of the source of a divalent metal and/or a trivalent metal, or the water-insoluble aluminum source and the source of a divalent metal and/or a trivalent metal can be added to the reactor at the same time.

[0028] Optionally, the resulting mixture and/or the separate sources are homogenized by, for instance, milling, high shear mixing or kneading. Especially when using insoluble metal sources such as oxides, hydroxides or carbonates, it is usually advisable to mill the metal sources. In one of the embodiments in which an aluminum source is used, both the water- insoluble aluminum source and the at least one source of a divalent metal and/or a trivalent metal - water-insoluble and/or precipitated - are milled. Even more preferably, a slurry comprising both the water-insoluble aluminum source and the at least one source of a divalent metal and/or a trivalent metal is milled. [0029] If desired, organic or inorganic acids and bases, for example for control of the pH, may be fed to the reactor or added to either the source of a divalent metal and/or a trivalent metal or the optional water-insoluble aluminum source before they are fed to the reactor. A preferred pH modifier is an ammonium base, because upon drying no deleterious cations will remain in the product.

[0030] Optionally the slurry of the first step can be subjected to an aging step prior to the heat treatment step. This aging can be performed under, or close to, ambient conditions, or under thermal or hydrothermal conditions. Within the context of this description "hydrothermal" means "in the presence of water (or steam) at a temperature above about 100⁰C at elevated pressure, e.g. autogenous pressure". The aging temperature can range from about 20° to about 400⁰C. A preferred temperature range is about 60 to about 175⁰C. Suitable atmospheres comprise CO₂, N₂, and air. The preferred atmosphere is air.

[0031] With this aging step it is possible, for instance, to convert the aluminum source, if present, into another aluminum source with improved binding properties. For instance, it is possible to convert aluminum trihydrate into boehmite.

[0032] According to these embodiments, the first step produces a solid product, either as a dry product containing at least one source of a divalent metal and/or a trivalent metal and optionally an aluminum source, or as a slurry of at least one source of a divalent metal and/or a trivalent metal and optionally an aluminum source, which slurry is optionally aged.

[0033] In case a slurry is produced in the first step, the solids are optionally separated by any means suitable, and dried prior to the heat treatment step. Suitable methods include spray drying and filtering using a filter bed. Filtering and drying the filtrated product gives a dry or semi-dry product that can be used in the heat treatment step. It is also possible to use the untreated slurry of the first step as such in the heat treatment step.

[0034] In the heat treatment step, the solids of the first step, i.e. the at least one source of a divalent metal and/or a trivalent metal, and optionally the aluminum source, is heat-treated. As indicated above, the at least one source of a divalent metal and/or a trivalent metal, and optionally the aluminum source, of the first step is a dry or semi-dry product or a slurry.

[0035] A heat treatment or some other method is performed to activate the product of the first step. The heat treatment is preferably performed for about one to about eight hours at a temperature of about 100 to about 500⁰C. The temperature is dependent on the cations present. The temperature should be high enough to activate the product, but not so high as to limit the activity. The heat treatment can be performed in air, nitrogen, oxygen or any other suitable gas.

[0036] In case a dry or semi-dry product is obtained after the first step, the heat treatment step can be a calcination step. The calcination can be performed under air in for example a muffle furnace, and can be conducted at temperatures between about 175° and about 1,000⁰C, preferably between about 200° and about 800⁰C, more preferably between about 400° and about 600⁰C, and most preferably around about 450⁰C. This calcination can be conducted for about 15 minutes to about 24 hours, preferably about 1 to about 12 hours, and most preferably about 2 to about 6 hours.

[0037J As a result of the heat treatment step, an oxide, hydroxide or oxyhydroxide of the at least one source of a divalent metal and/or trivalent metal is produced. This oxide, hydroxide or oxyhydroxide is in activated form so that the material reacts in an optimal way in the final contacting step.

[0038] In one of the embodiments of the invention, the heat treated product of the heat treatment step, after an optional milling step, is subjected to a rehydration step, followed by a further heat treatment step prior to the final contacting step. According to this embodiment, the heat-treated material of the heat treatment step is rehydrated in an aqueous suspension. This rehydration can be performed at thermal or hydrothermal conditions and optionally in the presence of dissolved metal salts, such salts including nitrates, carbonates, sulfates, oxalates of metals (e.g. Zn, Mn, Co, Ni, Cu, Ga, Cr, Fe, V, Mo, W, Ce, La, V, Pt, Pd, Ba, Ca, Rh, Si, Al, P, Mg, Al). In using such dissolved metal salts, it is important to keep the ratio TM:Me within the ranges described above.

[0039] If rehydration is performed, the obtained product is subsequently heat treated or calcined as described above to obtain a second heat treated material. This second heat treatment is performed under the conditions as indicated above for the first heat treatment step.

[0040] In the final contacting step, the heat treated product of the heat treatment step is contacted with an aqueous solution of at least one source of a transition metal. Suitable transition metals are preferably hexavalent transition metals like molybdenum (Mo), tungsten (W), rhenium (Re) and chromium (Cr). Preferred transition metals are those selected from the group consisting of Mo, W, and mixtures thereof.

[0041] The at least one source of a transition metal is preferably a salt of a transition metal, and is preferably selected from the group of sodium, potassium or ammonium molybdate or tungstate etc. Suitable compounds are ammonium hep tamo lybdate ((NH₄)(_SMo₇O₂₄-^H₂O), ammonium heptatungstate ((NH₄)OW₇O₂₄), potassium tetramo lybdate (K₂MoO₄), sodium tetramolybdate (Na₂MoO₄-2H₂O), sodium tetratungstate (Na₂WO₄-2H₂O), etc. Combinations of these compounds may also be used.

[0042] In the contacting step, an aqueous solution of at least one source of a transition metal is used. This aqueous solution of at least one source of a transition metal can be readily prepared by solubilizing at least one soluble source of a transition metal in water. Preferred transition metal compounds are soluble salts mentioned above.

[0043] In the method of the invention the contacting step is performed by adding a slurry of the heat treated material of the heat treatment step, after an optional milling step, to a solution of the at least one source of a transition metal, or vice versa. It is also possible to add the at least one source of a transition metal per se (i.e. as a solid) to the slurry of the heat treated product of the heat treatment step. In case the product of the heat treatment step is a solid, this solid can be added to a solution of the at least one transition metal or vice versa.

[0044] The way of blending the product of the heat treatment step with the aqueous solution of the at least one source of a transition metal, or with the at least one source of a transition metal in solid form, is generally speaking not critical, and can be done by adding the heat treated at least one source of a divalent polyvalent metal, optionally containing an aluminum source, to the (aqueous solution of) at least one source of a transition metal, oτ the other way round, in any suitable way. In case both products are in solid form, water or another suitable liquid medium must be added Iu provide a slurry containing both the source of a divalent metal and/or a trivalent metal, the optional aluminum source, and the transition metal source. However, it is preferred that at least one of the products to be blended (the source of a polyvalent metal, or the source of a transition metal) is present in a solution/slurry in water, to facilitate the blending. [004S] In an optional step, the product of contacting step is aged in the presence of the aqueous solution of the at least one source of a transition metal. According to this optional aging step, the slurry is aged at temperatures of between about room temperature and about 100⁰C, preferably between about 40° to about 80⁰C, more preferably between about 6O⁰C and about 70⁰C, for about 15 minutes to about 24 hours, preferably about 1 to about 12 hours, more preferably about 2 to about 6 hours, with or without stirring, and at about atmospheric or elevated pressure. Suitable atmospheres comprise CO₂, N₂, or air. The preferred atmosphere is air.

[0046] During this aging step, aluminum - if present as an insoluble aluminum- containing compound - is removed from the material as dissolved species. A washing and filtering step may optionally be performed in order to prevent at least a portion of the aluminum from becoming part of the resulting product. The so-formed product will comprise predominantly Anderson-type heteropolyanions with an X-ray diffraction pattern analogous to that of the known Anderson-type heteropolyanions. By 'predominantly Anderson-type heteropolyanion¹ is meant that the product will comprise more than about 50% and preferably more than about 70% of Anderson-type heteropolyanions.

[0047] Compositions comprising both an Anderson-type heteropolyanion and an aluminum-containing compound are obtained if an aluminum source was added to the at least one source of a divalent metal and/or a trivalent metal, and if no washing and filtering step is performed and/or if insoluble aluminum compounds are formed during aging by changing the aging conditions, e.g. increasing the pH and/or the temperature. The types of aluminum- containing compounds will depend on the aging conditions. Examples of such aluminum- containing compounds are aluminum oxides, hydroxides, or salts, for instance boehmite, e.g. pseudo- or microcrystalline boehmite, bayerite, amorphous oxide or hydroxide, metal aluminate, or aluminum molybdate. The amount of aluminum-containing compound in these compositions can range from about 1 to about 50 wt%, and is preferably between about 5 and about 50 wt%.

[0048] The aluminum-containing compound may be crystalline or amorphous, and have a high (greater than about 50 m²/g) or low (less than about 50 m²/g) specific surface area, depending on the preparation conditions. For instance, aging at hydrothermal conditions with intermediate addition of base to increase the pH can result in compositions comprising Anderson-type heteropolyanions and microcrystalline boehmite; whereas aging at lower temperatures and pressures can result in compositions comprising Anderson-type heteropolyanions and quasi-crystalline boehmite, i.e. pseudo-boehmite.

[0049] The Anderson-type heteropolyanions or Anderson-type heteropolyanion- containing compositions used in accordance with the present invention will generally be in the form of shaped bodies. This shaping can be conducted either after or during the preparation of the Anderson-type heteropolyanions or Anderson-type heteropolyanion- containing composition. For instance, in the above-described method the slurry of a divalent or trivalent metal source of the first step and optionally a water- insoluble aluminum source, can be shaped before performing heat treatment step, the heat treated product of the heat treatment step or the product of the contacting step can be shaped during the optional aging step by performing this step in a kneader which might be heated, or combinations thereof.

[0050] Suitable shaping methods include spray-drying, pelletizing, extrusion (optionally combined with kneading), beading, or any other conventional shaping method. The amount of liquid present in the slurry used for shaping should be adapted to the specific shaping step to be conducted. It might be advisable to (partially) remove the liquid used in the slurry and/or add an additional or another liquid, and/or change the pH of the precursor mixture to make the slurry gellable and thus suitable for shaping. Various additives commonly used in the various shaping methods, such as extrusion additives, may be added to the precursor mixture used for shaping.

[0051] Additives can be present in and/or on the Anderson-type heteropolyanions or Anderson-type heteropolyanion-containing compositions. Suitable additives comprise oxides, hydroxides, borates, zirconates, aluminates, sulfides, carbonates, nitrates, phosphates, silicates, titanates, and halides of rare earth metals (for instance Ce, La), Si, P, B, Group VI metals, Group VIII noble metals (e.g. Pt, Pd), alkaline earth metals (for instance Mg, Ca and Ba), and transition metals (for example W, V, Mn, Fe, Ti, Zr, Cu, Co, Ni, Zn, Mo, Sn).

[0052] The additives can be deposited on the Anderson-type heteropolyanions or Anderson-type heteropolyanion-containing compositions after the preparation thereof. Alternatively, they can be added during the above-described method in any of its steps, however, in that case it is imperative that the proper ratio of TM: {M(II)+M(III)} is maintained in order to ensure that the desired Anderson-type heteropolyanions are formed. [0053] The additives can for instance be added to the starting compounds, but can also be added separately in any of the slurries or solutions used in that process. Alternatively, the additives can be added just before the one or more heat treatment steps. Preferably, the slurry comprising the additive is milled.

[0054] If desired, the Anderson-type heteropolyanions or Anderson-type heteropolyanion-containing compositions may be subjected to ion-exchange. Upon ion exchange the interlayer charge-balancing cations, i.e. NH4⁺, are replaced with other cations. Examples of suitable cations are Na⁺, K⁺, AB⁺, Ni²⁺, Cu²⁺, Fe²⁺, Co²⁺, Zn²⁺, other transition metals, alkaline earth and rare earth metals, and pillaring cations such as [Al_{] 3}]⁷⁺ Keggin ions. In the above-described process said ion-exchange can be conducted before or after drying the Anderson-type heteropolyanions or Anderson-type heteropolyanion-containing compositions.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows the preparation scheme of Comparative Example 1, and the corresponding XRD patterns.

Figure 2 shows the preparation scheme of Example 1, and the corresponding XRD patterns.

Figure 3 shows the preparation scheme of Example 2, and the corresponding XRD patterns.

Figure 4 shows the preparation scheme of Example 3, and the corresponding XRD patterns.

Figure 5 shows the preparation scheme of Example 4, and the corresponding XRD patterns.

Figure 6 shows the preparation scheme of Example 5, and the corresponding XRD patterns.

Figure 7 shows the preparation scheme of Example 6, and the corresponding XRD patterns. Figure 8 shows the preparation scheme of Example 7, and the corresponding XRD patterns.

Figure 9 shows the preparation scheme of Example 8, and the corresponding XRD patterns.

Figure 10 shows the preparation scheme of Example 9, and the corresponding XRD patterns.

Figure 11 shows the preparation scheme of Example 10, and the corresponding XRD patterns.

Figure 12 shows the preparation scheme of Comparative Example 2, and the corresponding XRD patterns.

Figure 13 shows the preparation scheme of Comparative Example 3, and the corresponding XRD patterns.

Figure 14 shows an XRD pattern of Example 11.

Figure 15 shows another XRD pattern of Example 11.

Figure 16 shows the XRD pattern of Example 12.

Figure 17 shows the XRD pattern of Example 13.

Figure 18 shows an XRD pattern of Comparative Example 4.

Figure 19 shows another XRD pattern of Comparative Example 4.

Figure 20 shows an XRD pattern of Comparative Example 5.

Figure 21 shows another XRD pattern of Comparative Example 5. EXAMPLES

Example 1

[0055] Basic zinc carbonate, ZnCO₃^ZnO¹H₂O was calcined at 500⁰C for four hours in air in a muffle furnace. A portion of the calcined material (1.0 g) was heated to 85°C and aged overnight, while stirring in 163 g of an aqueous solution containing 17.1 g ammonium heptamolybdate. The Mo/Zn molar ratio was 8.8. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al, plus an unidentified extra phase characterized by a peak at 9° 2-theta (see Figure 2, pattern 2002-173-11).

[0056] A second portion of the calcined material (1.0 g) was heated to 85⁰C and aged overnight, while stirring in 310 g of an aqueous solution containing 34.2 g ammonium heptamolybdate. The Mo/Zn molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al. Increasing the Mo/Zn molar ratio from 8.8 to 17.5 decreased the intensity of the 9° peak that characterizes the unidentified phase (see Figure 2, pattern 2002-173-21).

[0057] A third portion of the calcined material (1.0 g) was heated to 85°C and aged overnight, while stirring in 398 g of an aqueous solution containing 68.3 g ammonium heptamolybdate. The Mo/Zn molar ratio was 34.8. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al. Only a very small intensity 9° 2-theta peak that characterizes the unidentified phase remains (see Figure 2, pattern 2002-173-31).

[0058] This Example is repeated with Fe as the divalent instead of Zn. The molar ratios are identical. Similar results are obtained.

Example 2

[0059] A 1:1 molar mixture of basic nickel carbonate, NiOHCO₃ and basic zinc carbonate, ZnCO₃ ^ZnO H₂O, was slurried in 130 g of distilled water. The resulting slurry was milled and then dried and subsequently calcined at 500⁰C for 4 hours. The calcined material (1.0 g) was then aged overnight at room temperature, while stirring in 14O g of an aqueous solution containing 27.0 g ammonium heptamolybdate. The Mo/(Zn+Ni) molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al (see Figure 3, pattern 2003-103-3).

[0060] This Example is repeated with Cu instead of Ni. The molar ratios are identical. Similar results are obtained.

Example 3

[0061] A mixture of 10.62 g flash calcined gibbsite (Alcoa CP^® alumina), basic nickel carbonate, and basic zinc carbonate was slurried in 17O g of distilled water. The (Zn+Ni):Al molar ratio was 2:1, whereas the Ni:Zn ratio was 25:75. The resulting slurry was milled and then dried and subsequently calcined at 500⁰C for 4 hours. The calcined material (1.0 g) was then aged overnight at room temperature, while stirring in 140 g of an aqueous solution containing 27.0 g ammonium heptamolybdate. The Mo/(Zn+Ni) molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al (see Figure 4, pattern 2003-101-3).

[0062] This Example is repeated with Cu and Zn instead of Ni and Zn, with a Mo/(Cu+Zn) molar ratio of 17.5. Similar results are obtained.

Example 4

[0063] A mixture of 10.62 g flash calcined gibbsite (Alcoa CP^® alumina), basic cobalt carbonate, CoOHCO₃ , and basic zinc carbonate, ZnCO₃-2ZnO H₂O, was slurried in 140 g of distilled water. The (Zn+Co):Al ratio was 2:1, whereas the Co:Zn ratio was 50:50. The resulting slurry was milled and then dried and subsequently calcined at 500⁰C for 4 hours. The calcined material (1.0 g) was then aged overnight at room temperature, while stirring in 150 g of an aqueous solution containing 27.0 g ammonium heptamolybdate. The Mo/(Zn+Co) molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al (see Figure 5, pattern 2003-111-3). [0064] This Example is repeated with Cu and Zn instead of Co and Zn. The Mo/(Zn+Cu) molar ratio is 17.5. Similar results are obtained.

Example 5

[0065] A mixture of 15.92 g flash calcined gibbsite (Alcoa CP® alumina) and 73.69 g basic zinc carbonate, ZnCCh^ZnO-H₂O, (Zn/ Al atomic ratio of 2:1) was slurried in 210 g of water. The slurry was milled. This slurry was aged overnight at 85⁰C. The resulting slurry was dried and subsequently calcined at 500⁰C for 4 hours in air in a muffle furnace. The calcined material (1.0 g) was then aged overnight at room temperature, while stirring in 210 g of an aqueous solution containing 24.7 g ammonium heptamolybdate. The Mo/Zn molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al (see Figure 6, pattern 2002-187-3).

[0066] This Example is repeated with W instead of Mo, using ammonium -hep tatungstate. The W/Zn molar ratio is 17.5. Similar results are obtained.

Example 6

[0067] A solution was prepared by dissolving 74.79 g aluminum nitrate monohydrate in 18O g distilled water. A second solution was prepared by dissolving 1 16.45 g zinc nitrate hexahydrate in 845 g distilled water. These two solutions were combined and added with vigorous stirring to a solution of 21.2 g sodium carbonate dissolved in 845 g distilled water, while maintaining the resulting slurry temperature at 65°C and the pH at 9 with 2M sodium hydroxide solution. The resulting co-precipitate was filtered, washed and dried at HO⁰C, then calcined at 500⁰C for four hours.

[0068] The calcined material (1.0 g) was then aged overnight at room temperature, while stirring in 250 g of an aqueous solution containing 26.46 g ammonium heptamolybdate. The Mo/Zn molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al (see Figure 7, pattern 2002-189-3).

[0069] This Example is repeated with Ni instead of Zn, and with W instead of Mo. The W/Ni molar ratio is 17.5. Similar results are obtained. Example 7

[0070] A solution was prepared by dissolving 186.99 g aluminum nitrate monohydrate in 527 g distilled water. A slurry prepared by dispersing 122.81 g basic zinc carbonate, ZnCO₃ 2ZnO H₂O, in 197 g distilled water (25% solids), was blended for thirty minutes in a Waring blender, then diluted to 10% solids with distilled water. The aluminum nitrate solution and zinc carbonate slurry were added simultaneously with vigorous stirring to a solution of 53 g sodium carbonate dissolved in 1437 g distilled water, while maintaining the resulting mixture at pH at 9 with addition of a 2 M sodium hydroxide solution and the temperature at 65°C. After the addition was completed the slurry was divided into two equal portions.

[0071] The first portion of the slurry was immediately filtered, washed and dried at 110⁰C, then calcined at 500⁰C for four hours. The calcined material (1.0 g) was then aged overnight at room temperature, while stirring in 240 g of an aqueous solution containing 25.28 g ammonium heptamolybdate. The Mo/Zn molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al (see Figure 8, pattern 2002-191-3).

[0072] The second portion of the slurry was aged overnight at 85⁰C, filtered, washed and dried at 110⁰C. According to the powder X-ray diffraction pattern, the product contained a well-crystallized LDH phase (see Figure 8, pattern 2002-191 -11).

[0073] This resulting product was then calcined at 500⁰C for four hours. The calcined material (1.0 g) was then aged overnight at room temperature, while stirring in 240 g of an aqueous solution containing 24.27 g ammonium heptamolybdate. The Mo/Zn molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al (sec Figure 8, pattern 2002-191-31).

[0074] This Example is repeated with Ce instead of Mo. The Ce/Zn molar ratio is 17.5. Similar results are obtained. Example 8

[0075] A zinc nitrate solution prepared by dissolving 58.2 g zinc nitrate hexahydrate in 54 g distilled water was precipitated by adding a dilute NH₄OH solution until the final pH was 9.1. To this precipitated zinc hydroxide 5.31 g flash calcined gibbsite (Alcoa CP^® alumina) was added (Zn/ Al atomic ratio of 2:1) and the resulting slurry was milled. This slurry was dried at 100⁰C and subsequently calcined at 500⁰C for four hours in air in a muffle furnace.

[0076] The calcined material (1.0 g) was then aged overnight at room temperature, while stirring in 140 g of an aqueous solution containing 27.O g ammonium heptamolybdate. The Mo/Zn molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al (see Figure 9, pattern 2003-99-3).

Example 9

[0077] A mixture of 22.94 g gibbsite and 73.69 g basic zinc carbonate, ZnCO₃'2ZnOΗ₂O, (Zn/ Al atomic ratio of 2:1) was slurried in 210 ml of water. The slurry was milled, dried and subsequently calcined at 500⁰C for 4 hours. The calcined material (1.5 g) was quickly added to 275 g of an aqueous solution containing 36.9 g ammonium heptamolybdate with stirring and aged overnight at room temperature. The Mo/Zn molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al (see Figure 10, pattern 2002-175-3).

[0078] A second portion of the calcined material (1.5 g) was added slowly over a period of fifteen minutes with stirring to 275 g of an aqueous solution containing 43.3 g ammonium heptamolybdate and was aged overnight at room temperature. The Mo/Zn molar ratio was 17 5 The product was filtered and washed. According io ihe powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al (see Figure 10, pattern 2002-175-4). Example 10

[0079] A highly dispersible boehmite alumina (Condea Disperal P3^®), 22.56 g, was slurried at 20% solids and blended in a Waring Blender for ten minutes. The resulting slurry was added to a second slurry prepared from 73.69 g basic zinc carbonate, ZnCO₃ -2ZnOH₂O, and 170 g distilled water (Zn/Al atomic ratio of 2:1). The slurry was milled, dried and subsequently calcined at 500⁰C for 4 hours, (see Figure 13, pattern 2002-33-2).

[0080] A first portion of the calcined material (1.0 g) was quickly added with stirring to 200 g of an aqueous solution containing 21.10 g ammonium heptamolybdate was and aged overnight at room temperature. The Mo/Zn molar ratio was 17.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al., plus an unidentified extra phase characterized by a peak at 9° 2-theta (see Figure 11, pattern 2002- 177-1).

[0081] A second portion of the calcined material (1.0 g) was treated as described above, except that the calcined material was added slowly over a period of fifteen minutes. The powder X-ray diffraction pattern showed a more highly crystallized product resulted from the fast addition process. The product contained a material structurally identical to the Anderson oxide reported by Allen et al. There is no unidentified extra phase (9° 2-theta) (see Figure 11, pattern 2002-177-2).

[0082] A third portion of the calcined material (1.0 g) was treated as described above, except that the powder was first dry milled in an analytical grinding mill (IKA Universalmuhler M-20), then added slowly, as described above. The X-ray diffraction pattern showed a highly crystallized product, similar to the product resulting from the third portion. The product contained a material structurally identical to the Anderson oxide reported by Allen et al (see Figure 11, pattern 2002-177-3).

Comparative Example 1

[0083] A portion of the calcined material of Example 1 (20 g) was heated to 85°C and aged overnight, while stirring in 252 g of an aqueous solution containing 69.8 g ammonium heptamolybdate. The Mo/Zn molar ratio was 1.9. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a cationic layered material (CLM) structurally identical to that reported by M.P. Astier et al., plus an unidentified extra phase characterized by peaks at 19° and 29° 2-theta (see Figure 1, pattern

2002-143-3).

Comparative Example 2

[0084] A mixture of 15.29 g gibbsite and 73.69 g basic zinc carbonate, ZnCO₃^ZnO-H₂O, (Zn/ Al atomic ratio of 3:1) was slurried in 270 ml of water. The slurry was milled, dried and subsequently calcined at 500⁰C for 4 hours. The calcined material (9.8 g) was quickly added to 550 g of an aqueous solution containing 31.6 g ammonium heptamolybdate with stirring and aged overnight at room temperature. The Mo/Zn molar ratio was 1.8. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a cationic layered material (CLM) structurally identical to that reported by M.P. Astier et al., plus an unidentified extra phase characterized by peaks at 19° and 29° 2-tlieta (see Figure 12, pattern 2002-39-3).

Comparative Example 3

[0085J A highly dispersible boehmite alumina (Condea Disperal P3^®), 22.56 g, was slurried at 20% solids and blended in a Waring Blender for ten minutes. The resulting slurry was added with stirring to a second slurry prepared from 73.69 g basic zinc carbonate, ZnCC>₃ -2ZnO-I^O, and 170 g distilled water (Zn/ Al atomic ratio of 2:1). The slurry was milled, dried and subsequently calcined at 500⁰C for 4 hours. The calcined material (5.0 g) was quickly added to 285 g of an aqueous solution containing 16.19 g ammonium heptamolybdate with stirring and aged overnight at room temperature. The Mo/Zn molar ratio was 2.0. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a cationic layered material (CLM) structurally identical to that reported by M.P. Astier et al., plus an unidentified extra phase characterized by peaks at 19° and 29° 2-theta (see Figure 13, pattern 2002-33-3).

Example 11

[0086] Basic nickel carbonate, NiCO₃ -2Ni(OH)2 -4H₂O was calcined at 200⁰C for six hours in air in a muffle furnace. The calcined material (2.5 g) was added to 411 g of a solution containing 82.2 g ammonium heptamolybdate. The resulting slurry was heated to 65⁰C with stirring and aged overnight. The Mo/Ni mole ratio was 20. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al. (See Figure 14, pattern 2003-115-122).

[0087] A second portion of the calcined material (2.5 g) was treated as described above, except the slurry was aged overnight with stirring at ambient temperature. As before the Mo/Ni mole ratio was 20. The product was filtered and washed. According to the powder X- ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al. (See Figure 15, pattern 2003-115-112).

Example 12

[0088] Basic nickel carbonate, NiCO₃ -2Ni(OH)2-4H₂O was calcined at 300⁰C for six hours in air in a muffle furnace. The calcined material (2.5 g) was added to 557 g of a solution containing 111.4 g ammonium heptamolybdate. The resulting slurry was heated to 65°C with stirring and aged overnight. The Mo/Ni mole ratio was 20. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al. (See Figure 16, pattern 2003-121-122).

[0089] A second portion of the calcined material (2.5 g) was treated as described above, except the slurry was aged overnight with stirring at ambient temperature. As before the Mo/Ni mole ratio was 20. The product was filtered and washed. According to the powder X- ray diffraction pattern, the product contained a cationic layered material structurally identical to the Anderson oxide reported by Allen et al.

Example 13

[0090] Basic copper carbonate, CuCO₃ -2Cu(OH)2 was calcined at 300⁰C for six hours in air in a muffle furnace. The calcined material (0.75 g) was added to 429 g of a solution containing 32.2 g ammonium heptamolybdate. The resulting slurry was aged overnight with stirring at ambient temperature. The Mo/Cu mole ratio was 20. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to the Anderson oxide reported by Allen et al., plus an unidentified extra phase (See Figure 17, pattern 2003-137-112).

Comparative Example 4

[0091] Basic copper carbonate, CuCO₃ -2Cu(OH)2 was calcined at 200⁰C for six hours in air in a muffle furnace. The calcined material (5.0 g) was added to 75 g of a solution containing 4.0 g ammonium heptamolybdate. The resulting slurry was heated to 65°C with stirring and aged overnight. The Mo/Cu mole ratio was 0.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a material structurally identical to that reported by M.P. Astier et al. (See Figure 18, pattern 2003-131- 121).

[00921 A second portion of the calcined material (5.0 g) was treated as described above, except the slurry was aged overnight with stirring at ambient temperature. As before the Mo/Cu mole ratio was 20. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a cationic layered material (CLM) structurally identical to that reported by M.P. Astier et al. (See Figure 19, pattern 2003-131- 111).

Comparative Example 5

[0093] Basic copper carbonate, CuCO₃ -2Cu(OH)2 was calcined at 300⁰C for six hours in air in a muffle furnace. The calcined material (4.0 g) was added to 75 g of a solution containing 4.3 g ammonium heptamolybdate. The resulting slurry was heated to 65⁰C with stirring and aged overnight. The Mo/Cu mole ratio was 0.5. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a cationic layered material (CLM) structurally identical to that reported by M.P. Astier et al. (See Figure 20, pattern 2003-137-121).

[0094] A second portion of the calcined material (4.0 g) was treated as described above, except the slurry was aged overnight with stirring at ambient temperature. As before the Mo/Cu mole ratio was 20. The product was filtered and washed. According to the powder X-ray diffraction pattern, the product contained a cationic layered material (CLM) structurally identical to that reported by M.P. Astier et al. (See Figure 21, pattern 2003-137- 111).

Claims

1. A method for preparing an Anderson-type heteropolyanion comprising steps to provide at least one solid source of a polyvalent metal Me, heat treating the at least one solid source of a polyvalent metal Me, and contacting the heat treated polyvalent metal Me with an aqueous solution of at least one source of a transition metal TM, wherein the polyvalent metal Me is not the same as the transition metal TM, and wherein the atomic ratio TMrMe is at least about 2.5.

2. The method of claim 1 wherein the atomic ratio TM:Me is at least about 5.0.

3. The method of claim 2 wherein the atomic ratio TM:Me is at least about 8.8.

4. The method of claim 1 wherein the polyvalent metal is a divalent metal M(II) selected from the group consisting of Zn(II), Fe(II), Co(II), Cu(II), Ni(II), Mn(II), Ca(II), Ba(II), Sr(II), Mg(II), and mixtures thereof.

5. The method of claim 1, wherein the polyvalent metal is a trivalent metal M(III) selected from the group consisting of Al(III), Ga(III), Fe(III), Cr(III), Co(III), RIi(III), Ce(III), and mixtures thereof.

6. The method of claim 1, wherein the polyvalent metal is a tetravalent metal M(IV) selected from the group consisting of Mn(IV), Ni(IV), Te(IV) and mixtures thereof.

7. The method of claim 1, wherein the polyvalent metal is a pentavalent metal M(V).

8. The method of claim 1, wherein the polyvalent metal is a hexavalent metal M(VI).

9. The method of claim 1, wherein the polyvalent metal is a heptavalent metal M(VII).

10. The method of claim 1, wherein the transition metal TM is selected from the group consisting of Mo, W, and mixtures thereof.

11. The method of claim 1, wherein the first step further comprises preparing an aqueous slurry of the at least one source of a polyvalent metal.

12. The method of claim 11, wherein the aqueous slurry of the at least one source of a polyvalent metal is prepared by mixing at least one insoluble compound comprising a polyvalent metal with water.

13. The method of claim 12 wherein the at least one insoluble compound comprising a polyvalent metal is the oxide, hydroxide, carbonate, oxycarbonate, or hydroxy carbonate of a polyvalent metal, or mixtures thereof.

14. The method of claim 11, wherein the aqueous slurry of the at least one source of a polyvalent metal is prepared by providing an aqueous solution of at least one soluble compound comprising the polyvalent metal, and increasing the pH to precipitate the polyvalent metal.

15. The method of claim 14, wherein the soluble compound comprising a polyvalent metal is a salt of a polyvalent metal.

16. The method of claim 15, wherein the salt of a polyvalent metal is a nitrate, formate, acetate, chloride or oxalate of a polyvalent metal.

17. The method of claim 11 wherein an aluminum source is present in the slurry.

18. The method of claim 17 wherein the aluminum source is selected from the group consisting of alumina, a soluble aluminum salt, and mixtures thereof.

19. The method of claim 18 wherein the alumina is selected from the group consisting of alumina gel, gibbsite, bayerite, boehmite, pseudoboehmite, aluminum trihydrate, or flash-calcined aluminum trihydrate.

2⁽J. The method of claim 11 wherein the slurry is subjected to an aging step prior to the heat treatment step.

21. The method of claim 11 wherein the solids are separated from the slurry and dried prior to the heat treatment step.

22. The method of claim 11 wherein the heat treatment step is carried out in air, nitrogen or oxygen at a temperature in the range of from about 100 to about 1000 deg. C

23. The method of claim 22 wherein the heat treatment is a calcination step, carried out in air at a temperature in the range of from about 175 to about 1000 deg. C.

24. The method of claim 21 wherein the product obtained in the heat treatment step is subjected to a rehydration step, followed by a further heat treatment step, prior to the contacting step.

25. The method of claim 1, wherein the at least one source of a transition metal TM is a soluble salt of the transition metal TM.

26. The method of claim 25 wherein the soluble salt of the transition metal TM is an ammonium, potassium or sodium salt of the transition metal TM,

27. The method of claim 25 wherein the soluble salt of the transition metal TM is ammonium heptamolybdate or ammonium heptatungstate.

28. The method of claim 1 wherein the heat treated product of the contacting step is aged in the presence of the aqueous solution of the at least one source of a transition metal TM.

29. The method of claim 28 wherein the aging is carried out at a temperature between about room temperature and about 100 deg. C for a period of about 15 minutes to about 24 hours.

30. An Anderson-type heteropolyanion produced by providing at least one solid source of a polyvalent metal Me, heat treating the at least one solid source of a polyvalent metal Me, and contacting the heat treated polyvalent metal Me with an aqueous solution of at least one source of a transition metal TM, wherein the polyvalent metal Me is not the same as the transition metal TM, and wherein the atomic ratio TM:Me is at least about 2.5.

31. The Anderson-type heteropolyanion of claim 30 wherein the polyvalent metal is a divalent metal M(II) selected from the group consisting of Zn(II), Fe(II), Co(II), Cu(II), Ni(II), Mn(II), Ca(II), Ba(II), Sr(II), Mg(II), and mixtures thereof.

32. The Anderson-type heteropolyanion claim 30, wherein the polyvalent metal is a trivalent metal M(III) selected from the group consisting of Al(III), Ga(III), Fe(III), Cr(III), Co(III), Rh(III), Ce(III), and mixtures thereof.

33. The Anderson-type heteropolyanion claim 30, wherein the transition metal TM is selected from the group consisting of Mo, W, and mixtures thereof.