AU704624B2 - Aluminosilicate cation exchange compounds - Google Patents

Description

WO 96/12674 PCT/AU95/00320 -1- ALUMINOSILICATE CATION EXCHANGE COMPOUNDS TECHNICAL FIELD This invention relates to aluminosilicate compounds which have cation exchange capacity and is particularly concerned with such materials having a stuffed silica polymorph-related structure in which the aluminium is tetrahedrally coordinated.

BACKGROUND ART Kalsilite, nepheline, carnegieite and eucryptite are all crystalline minerals of ideal composition MAISiO 4 where M is an alkali metal, having a stuffed silica polymorph-related structure in which the aluminium is tetrahedrally coordinated.

Kalsilite has ideal composition KAISiO 4 while nepheline exists as a solid-solution and has the composition Na,, KAlSiO4, where Osx< 1. Both of these minerals have crystal structures closely related to that of the silica polymorph, tridymite (see Figure Carnegieite has ideal composition NaAISiO 4 and has a crystal structure closely related to that of the silica polymorph, cristobalite (see Figure 2).

Eucryptite has ideal composition LiAISiO 4 and has a crystal structure closely related to that of the silica polymorph, quartz (see Figure 3).

Tridymite, cristobalite and quartz all have the composition SiO 2 and consist of a 3dimensional framework of corner-connected SiO 4 tetrahedra. Kalsilite, nepheline, carnegieite and eucryptite have been described as stuffed derivatives of the tridymite, cristobalite or quartz structures, in that half of the silicon cations in the silicate framework it each case are replaced by aluminium cations. Alkali cations, which are required for charge balance (Si 4

A

3 M M alkali) occupy the interstices in the respective frameworks (see Figures 1-3) hence the descriptions "stuffed tridymite", "stuffed cristobalite", and "stuffed quartz".

In kalsilite, nepheline, carnegieite and eucryptite, the interstitial cations, M are WO 96/12674 PCT/AU95/00320 -2not exchangeable under normal conditions, that is, in aqueous salt solution at atmospheric pressure up to -100 Therefore, kalsilite, nepheline, carnegieite and eucryptite have negligible cation exchange capacity (CEC). Any CEC is associated with the surface of crystals and not the bulk of the structure.

It has been proposed in, for example, Roux, 1971, C.R. Acad. Sci., Ser D 272, 3225-3227 to exchange the interstitial cations of kalsilite and related aluminosilicates by treating the material at high temperature and pressure under hydrothermal conditions.

It has also been proposed by Sobrados Gregorkiewitz, 1993, Physics and Cherhistry of Minerals, 20, 433-441 to achieve similar exchange of cations by treating kalsilite and related materials with molten salts such as MNO 3 or MCI (M Li, Na, K, Ag).

However, it is widely accepted that aluminosilicates with the stuffed tridymite-type structure have no cation exchange capacity associated with the bulk structure, either in aqueous solution or in organic solvents.

It has been proposed in, for example, Petranovic et al, 1991, Materials Science Monograph, 666, 2229-2236, that it is possible to exchange the interstitial Na cation of carnegieite with Li by treating it with molten LiNO 3 Associated with this ability to exchange cations by treatment with molten salts is the property of ionic conductivity which has been observed for carnegieite and related materials.

It is also expected that, as for kalsilite and nepheline, exchange of the interstitial cations might be induced under aqueous conditions provided the material were subjected to sufficiently high temperatures and pressures, i.e. under hydrothermal conditions.

However, it is widely accepted that aluminosilicates with the stuffed cristobalite-type structure have no cation exchange capacity associated with the bulk structure, either 1~ WO 96/12674 PCT/AU95/00320 -3in aqueous solution or in organic solvents.

It has been proposed in, for example, Berchot et al, 1980, Journal of Solid State Chemistry, 34, 199-205, that while it is not possible to substitute Li' in p-eucryptite by treatment using molten salts with bigger cations such as Na*, K+ or Ag exchange by divalent cations Cu 2 and Mn 2 is possible under such conditions.

However, it is widely accepted that aluminosilicates with the stuffed quartz-type structure have no cation exchange capacity associated with the bulk structure, either in aqueous solution or in organic solvents.

Amorphous derivatives of kaolinite and/or halloysite having large surface areas (BET surface area of at least 45 m 2 g 1 and caton exchange capacity are described in International patent application W095/00441 and related applications (including in the United States of America), the contents of which are incorporated herein by reference.

In WO95/00441 the amorphous derivatives of kaolinite and/or halloysite (referred to as "KAD") are produced by a process which comprises reacting a kaolin group mineral with an aqueous alkali halide, wherein the mole ratio of alkali metal halide to the kaolin group mineral is from 5 to the saturation concentration of the alkali metal halide. KAD is characterised as a result of this production process by the presence of halide and substantial amounts of structural water, whether as bound water or as hydroxyl, in its composition.

SUMMARY OF THE INVENTION According to the present invention there is provided a poorly or partly crystalline alkali metal aluminosilicate material having a stuffed silica polymorph-related structure in which the aluminium is predominantly tetrahedrally coordinated and a cation exchange capacity (CEC) at room temperature of at least 1 meq 100 in aqueous solution, which is produced by reacting an aluminosilicate, or a WO 96/12674 PCT/AU95/00320 -4combination of aluminium oxide-containing and silicon oxide-containing compounds, with an alkali oxide-containing reagent. Compounds in accordance with the invention are, for convenience only, hereinafter collectively referred to as XAM.

Also according to the present invention, there is provided a process for the preparation of a poorly or partly crystalline alkali metal aluminosilicate material having a stuffed silica polymorph related-structure in which the aluminium is predominantly tetrahedrally coordinated a- J a cation exchange capacity at room temperature of at least 1 meq 100g' 1 in aqueous solution, in which an aluminosilicate, or a combination of aluminium oxide-containing and silicon oxide containing compounds, are reacted together with an alkali oxide-containing reagent.

Further, the present invention extends to uses of XAM and/or of XAM which has been subjected to partial or full exchange of the alkali metal cation.

By stuffed silica polymorph-related structure is meant any alkali metal aluminosilicate material with the structure type of any of the stuffed silica polymorphs defined above. The interstitial cation may therefore be K Na 4 or Li', as in kalsilite, carnegieite, or eucryptite, respectively. When XAM is prepared with K' as the interstitial cation a kalsilite-related structure is obtained, when prepared with Na+ a carnegieite-related structure is obtained, and when prepared with Li* a eucryptite-related structure is obtained. XAM may be prepared with other alkali cations, Rb and Cs', in which cases kalsilite-related structures are obtained. The interstitial sites in XAM may also be occupied by a mixture of two or more such cations, as in nepheline, or a mixture of alkali metal and one or more other cations, such as transition metal cations and alkaline earth cations. XAMs involving mixtures of interstitial cations typically possess the stuffed silica polymorph-related structure of the dominant interstitial cation. Alkali metal cations are the preferred cations, in particular K Na and Li+.

Central to the present invention is the discovery that XAM can have a significant CEC in aqueous solution at room temperature. XAM preferably has a CEC of at WO 96/12674 PCT/AU95/00320 least 5 milliequivalents per 100 grams (meq 100g'), most preferably greater than meq 100g', and in many embodiments will have a CEC of at least 100 meq 100g 1 When well-prepared, XAM may have a CEC 250 meq 100g for example up to 750 meq 100g'', with a significant majority of the interstitial cations being exchangeable by other cations in aqueous solution at room-temperature. This discovery is in contrast to the properties of well-crystallised, ordered kalsilite-, nepheline-, carnegieite-, and eucryptite-type aluminosilicates which have CECs typically less than 1 meq 100 g' 1 per 100 grams.

XAM can be prepared by a large number of synthetic processes preferably involving solid state reactions, and several of these processes are described below. Essential to the synthesis of XAM are reactive starting materials, that is, components or component precursors which facilitate reaction at relatively low temperatures.

More rigorous conditions normally associated with the formation of aluminosilicates such as kalsilite and carnegieite, for example, annealing components at 1000 *C overnight, produce materials which do not display the cation exchange properties of XAM, and which are normally well-crystallised and ordered.

To facilitate relatively mild reaction conditions for the formation of XAM it is advantageous to use an aluminosilicate starting material which, by definition, contains aluminium and silicon cations mixed on the unit cell, that is the nanometre, scale.

Aluminosilicate phyllosilicates are, in general, suitable reactive starting materials for the formation of XAM. Sach phyllosilicates include the clay minerals, illite, vermiculite, montmorillonite, beidellite, bentonite, kaolinite and halloysite, as well as the minerals, pyrophyllite, muscovite and palygorskite. While there is a significant range in the silicon and aluminium contents among these starting materials, all are considered, to a greater or lesser extent, to be a suitable source of aluminosilicate in the synthesis of XAM. Other aluminosilicate minerals such as zeolites, imogolite and allophane, are also considered suitable.

WO 96/12674 PCT/AU95/00320 -6- One of the other advantages that mineral aluminosilicates have as reactive starting materials is their high natural abundance and low unit cost.

Various alkali salts and hydroxides are suitably reactive starting materials which provide a source of the alkali cations. Most alkali salts which decompose upon heating at a temperature up to 1000 "C to give alkali oxide are suitable. The most preferred salts are carbonates. Other preferred salts are bicarbonates, nitrates and carboxylates.

It is also possible to use reactive forms of silica, such as silica gel and colloidal silica, in combination with reactive forms of alumina, such as aluminium nitrate nonahydrate, bayerite and aluminium hydroxide gel, to provide the source of aluminosilicate for the formation of XAM. Alternatively, possible combinations of reactive starting materials are sodium nitrate or sodium carbonate with aluminosilicic gel, and gibbsite or boehmite with sodium silicate glass.

Preferred reaction conditions are 750 0 C or less, for example 300 °C to 750 *C at atmospheric pressure for periods of time of, for example, 15 minutes to 24 hours.

Reaction in air in an open vessel is preferred, but the reaction will proceed under different atmospheres and/or under reduced pressure provided the system is not closed.

BRIEF DESCRIPTION OF THE DRAWINGS Various embodiments of XAMs, uses for them and processes for producing them will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 shows polyhedral representations of high-tridymite (SiO z and kalsilite (KAISiO 4 projected down the 110 direction. The structure of kalsilite shows the layers of interstitial and framework cations (dashed lines) which give rise to the strong X-ray diffraction (XRD) peak at 3.1 A; Figure 2 shows polyhedral representations of high-cristobalite (SiO 2 and WO 96/12674 PCT/AU95/00320 -7high-carnegieite (NaAISiO 4 projected down the cubic <110> direction. The structure of high-carnegieite shows the layers of interstitial and framework cations (dashed lines) which give rise to the strong X-ray diffraction peaks at 4.2 and 2.6 A; Figure 3 shows polyhedral representations of high-quartz (SiO 2 and higheucryptite (LiAISiO 4 projected down the <110> direction. The structure of higheucryptite shows the layers of interstitial and framework cations (dashed lines) which give rise to the strong X-ray diffraction peak at 3.6 A; Figure 4 shows 2 Al MAS NMR spectra collected at 104.228 MHz of a) K- XAM prepared according to a first process described below using kaolinite and

K

2 C0 3 heated for 3 hours at 500 C (Example and b) Na-XAM prepared according to the first process using kaolinite and Na 2

CO

3 heated for 3 hours at 500 0 C (Example 4); Figure 5 shows XRD profiles of K-XAM and Na-XAM prepared according to Examples 1 and 3, respectively. The XRD profiles of the same K-XAM and Na-XAM heated at 1000 C for 16 hours showing well crystallised kalsilite (peaks indicated by and nepheline (peaks indicated by are juxtaposed. Nepheline is the thermodynamically stable form of NaAISiO 4 under these conditions; Figure 6 shows XRD profiles of K-XAM prepared according to Example 2. The XRD profiles of the same K-XAM heated at 850 0 C 900 0 C and 1000 C for 16 hours are juxtaposed. The series shows progressive increase in crystallinity with temperature, particularly the evolution of the broad peak at 29 2 e into the strong sharp 102 reflection of well-crystallised kalsilite. Peaks belonging to well crystallised kalsilite are indicated by Figure 7 shows XRD profiles of Na-XAM prepared according to Example 4. The XRD profiles of the same Na-XAM heated at 665 0 C 800 *C 900 *C and 1000 "C for 16 hours are juxtaposed. The series shows the increase in crystallinity with temperature, particularly the evolution of the broad composite peak between -18° and -34° 20 into the strong sharp 111 and 220 reflections of well-crystallised high-carnegieite, followed by transformation into wellcrystallised nepheline. Peaks belonging to well-crystallised carnegieite and nepheline WO 96/12674 PCT/AU95/00320 -8are indicated by and respectively; Figure 8 shows XRD profiles of Li-XAM prepared according to Example and Example 6 Rb-XAM prepared according to Example 10 and Cs- XAM prepared according to Example 11 The XRD profiles of the same Li- XAM (Example 6) Rb-XAM and Cs-XAMv heated at 1000 C for 16 hours are juxtaposed. Figure 8f and 8c show the evolution of the broad composite peak between 18 and 25 28 into the sharp 100 and 102 reflections of wellcrystallised high-eucryptite at 1000 C (peaks indicated by Figures 8a and 8b show XRD profiles of well-crystallised Cs- and Rb-containing kalsilite-related materials, respectively (peaks indicated by and respectively); Figure 9 shows XRD profiles of mixed K/Na-XAM and Na-XAM (c) prepared according to Examples 7 and 20, respectively. The XRD profiles of the same K/Na-XAM and Na-XAM heated at 1000 *C for 16 hours showing well crystallised kalsilite-type (peaks indicated by and nepheline (peaks indicated by are juxtaposed; peaks indicated by belong to partly crystalline carnegieite; Figure 10 shows XRD profiles of the series of K-XAMs prepared according to Example 12, 0.33 g K 2

CO

3 0.49 g K 2

CO

3 0.66 g K 2

CO

3 and of Na- XAMs prepared according to Example 14, 43.7 g Na 2

CO

3 and 131 g Na 2

CO

3 The XRD profiles of the same Na-XAMs heated at 1000 C for 16 hours showing well-crystallised nepheline and carnegieite (peaks indicated by and respectively) are given as 1Ob (43.7 g) and 10a (131 g); Figure 11 shows XRD profiles of K-XAMs prepared according to Example 8 Example 15 potassium nitrate and potassium acetate and of Na-XAMs prepared according to Example 9 Example 16 sodium nitrate and sodium citrate Figure 12 shows XRD profiles of K-XAM and Na-XAM prepared from montmorillonite according to Example 17. The XRD profiles of the same K- XAM and Na-XAM heated at 1000 *C for 16 hours showing well crystallised leucite-like (peaks indicated by and albite-like (peaks indicated by phases, respectively, are juxtaposed; Figure 13 shows XRD profiles of K-XAM and Na-XAM prepared from pyrophyllite according to Example 18. The XRD profiles of the same K-XAM WO 96/12674 PCT/AU95/00320 -9and Na-XAM heated at 1000 C for 16 hours showing similar broad diffraction features to the as-prepared XAMs are juxtaposed. In the as-prepared M-XAMs, diffraction peaks due to quartz impurity and unreacted pyrophyllite are indicated by and o, respectively; Figure 14 shows XRD profiles of K-XAM and Na-XAM prepared from colloidal silica, aluminium nitrate and alkali carbonate according to Example 19. The XRD profiles of the same K-XAM and Na-XAM heated at 1000 *C for 16 hours showing well crystallised kalilite-like and carnegieite-like phases, respectively, are juxtaposed. Peaks belonging to well-crystallised carnegieite, nepheline and kalsilite are indicated by and respectively; Figure 15 shows XRD profiles of Na-XAMs prepared from colloidal silica, aluminium nitrate and sodium carbonate according to Example 21 at AI:Si ratios of 0.2:1.0 and 2.0:1.0 The XRD profiles of the same Na-XAMs heated at 1000 C for 16 hours, 0.2:1.0 and 2.0:1.0 showing unchanged profiles are juxtaposed.

DETAILED DESCRIPTION OF THE INVENTION Structure and composition of XAM.

XAM is most uniquely characterised in terms of its structure and composition.

The structures of the various M-XAMs (M alkali metal) are characterised most definitively by X-ray powder diffraction. When well prepared the various M-XAMs give X-ray powder diffraction profiles which display the broad diffraction peaks characteristic of the protocrystalline stuffed silica polymorphs. They are not amorphous, as their X-ray powder diffraction profiles display nascent diffraction peaks of the stuffed silica polymorphs. The diffraction profile in each case is primarily dependent on the alkali metal, M. The characteristic XRD profiles for the various M-XAMs can be seen in Figures 5 9.

Further verification that a material is XAM can be obtained by heating these poorly WO 96/12674 PCT/AU95/00320 or partly crystalline materials at sufficiently high temperature for sufficient time that they become well-crystallised, for example, at 1000 *C for 16 hours. Provided the stoichiometry of the XAM is reasonably close to that of one of the ideal stuffed silica polymorphs, kalsilite, nepheline, carnegieite or eucryptite, namely MAlSiO4, M alkali metal, then the dominant peaks in the XRD of the crystalline material will be characteristic of one or more of these polymorphs.

If the stoichiometry of the XAM is significantly different from one of the ideal stuffed silica polymorphs, then other crystalline phases, for example, albite, NaAISi 3 Og and leucite, KAlSi20 6 can be observed (see Figures 12b and 12a, respectively). If the stoichiometry of the XAM is sufficiently exotic or the framework atoms not sufficiently homogeneous then it is possible that the poorly crystalline XAM will not transform into a more crystalline solid under these conditions (see Figures 15a and Furthermore, as the structure of XAM is related to the stuffed silica polymorphs, it also comprises a framework aluminosilicate structure in which both the silicon and aluminium cations are tetrahedrally coordinated. 'Al nuclear magnetic resonance (NMR) is sensitive to the coordination environment of aluminium, that is, whether the cation is 4, 5 or 6 coordinated. The TAl magic angle spinning (MAS) NMR spectra of K-XAM and Na-XAM prepared at 500 0 C each give a single peak at 57 ppm (FWHM 23 ppm) (see Figure 4) which is interpreted as tetrahedrally coordinated aluminium. For these materials there is evidence of only very minor proportions (5 of octahedrally coordinated aluminium due possibly to unreacted starting material, kaolinite in which the aluminium is octahedrally coordinated, or to reaction byproducts or mineral impurities containing octahedrally coordinated aluminium.

The XRD profiles observed for XAMs are dependent on the choice of starting reagents and reaction conditions. They are also sometimes complicated by the presence of unreacted starting materials, reaction byproducts or impurity minerals, such as quartz and anatase, when naturally-occurring components are used.

WO 96/12674 PCT/AU95/00320 -11 When K-XAM is poorly crystalline and free from unreacted starting material and reaction byproducts, its XRD profile comprises a single very broad diffraction peak (see Figures 5d and 6d) which corresponds to the 102 reflection in kalsilite. This broad peak indicates that, while other long-range ordering is absent in these poorly crystalline K-XAMs, there is still periodic structure (protocrystallinity) associated with the layers of interstitial and framework cations (refer to -3.1 A layers indicated by dashed lines in Figure When heated at higher temperatures the K- XAM transforms into well-crystallised kalsilite and the resultant diffraction peaks can be indexed accordingly.

When Rb-XAM and Cs-XAM are poorly crystalline and free from unreacted starting material and reaction byproducts their XRD profiles (Figures 8e and 8d respectively) are dominated by a single very broad diffraction peak corresponding to the 202 reflections of their kalsilite-related structures (see Table As for K- XAM these broad peaks are associated with slightly increased layer spacing due to the larger cation size. When heated at higher temperatures the Rb-XAM and Cs- XAM transform into well-crystallised kalsilite-related materials (Figures 8b and 8a respectively) and the resultant diffractions patterns can be indexed accordingly.

When Na-XAM is poorly crystalline and free from unreacted starting material and reaction byproducts its XRD profile comprises a composite of two overlapping broad diffraction peaks (see Figures 5c and 7e) which correspond to the 111 and 220 peaks of high-carnegieite. These broad peaks indicate that, while other longrange ordering is absent in these poorly crystalline Na-XAMs, there is still periodic structure (protocrystallinity) associated with the layers of interstitial and framework cations (refer to 4.2 and 2.6 A layers indicated by dashed lines in Figure 2).

When heated at higher temperatures the peaks initially sharpen and other highcarnegieite peaks appear (see Figure then upon further heating the material begins to transform to well-crystallised nepheline and the resultant diffraction peaks can be indexed accordingly.

When Li-XAM is poorly crystalline and free from unreacted starting material and WO 96/12674 PCI/A U95/00320 12 reaction byproducts its XRD profile comprises a composite of two broad overlapping diffraction peaks (see Figure 8f) which corresponds to the 100 and 102 peaks of high-eucryptite. This broad composite peak indicates that, while other long-range ordering is absent in these poorly crystalline Li-XAMs, there is still periodic structure (protocrystallinity) associated with the layers of interstitial and framework cations (refer to 3.6 A layers indicated by dashed lines in Figure 3).

When heated at higher temperatures the Li-XAM transforms into well-crystallised eucryptite and the resultant diffraction peaks can be indexed accordingly.

The d-spaci,s, relative intensities and derived unit cell dimensions for selected examples of these well-crystallised materials derived from Cs-XAM, Rb-XAM, K- XAM, Na-XAM and Li-XAM are listed in Table 1.

Table 1 Crystallographic data of well-crystallised materials derived from various XAMs in Figures 5-8.

Example 1 heated to 1000 C Example 2 heated to 1000 *C Kalsilite Kalsilite d(A) I/I o hkl d(A) I/I o hkl 4.31 37 002 4.51 12 100 3.11 100 102 4.31 23 002 2.60 34 110 3.11 100 102 2.22 13 112 2.60 43 110 2.15 20 004 2.23 11 112 1.55 8 204 2.15 15 004 Hexagonal a 5.208(1) A Hexagonal a 5.207(2) A c 8.616(1) A c 8.609(4) A WO 96/12674 WO 9612674PCTIAU95/0032) 13 ffExample 11 heated to 1000 0 C Example 10 heated to 1000 0

C

Kalsilite-related Kalsilite-related d(A) I/ia hkl d(A) I/10 hkl 4.70 25 200 4.63 6 200 3.26 100 202 1324 24 211 2.94 16 301 3.18 100 202 2.71 28 310 2.79 8 103 2.32 20 022 2.67 27 310 2.31 7 400 Orthorhomubic a 9.36(3) A 2.27 14 022 b 5.39(2) A 2.18 14 004 c 9.07(7) A 1.98 6 114 1.72 7 105 1.54 8 330 Orthorhombic a 9.249(4)A b 5.319(4)A c 8.767(3)A w I WO 96/12674 WO 9612674PCT/VAU95/0032) -14 Example 3 heated to 1000 0

C

Nepheline

-F

Example 4 heated to IUOOOC Nepheline d(A) 8.70 5.00 4.34 4.17 3.84 3.27 3.05 3.00 2.88 2.57 2.50 2.40 2.34 2.31 2.12 2.08 1.79 1.56 Hexagonal

I/I.

5 12 59 90 98 59 21 100 36 19 17 14 42 26 12 17 10 20 bid 100 110 200 002 201 210 211 202 300 212 220 310 203 311 213 322 205 d(A) 8.65 4.99 4.32 4.17 3.84 3.27 3.04 3.00 2.88 2.57 2.50 2.40 2.34 2.30 2.12 2.08 1.79 1.56 Hexagonal 1/Ia 9 15 39 80 100 72 16 89 39 23 13 10 45 25 11 18 6 17 hkl 100D 110 200 002 201 210 211 202 300 212 220 310 203 311 213 004 322 205 a 10.000(3)A c 8.341(3) A a 9.979(l) c 8.336(2)

'I

WO 96/12674 PCT/AU95/00320 CIIIIIICI Example 4 heated to 800 *C High-carnegieite Example 6 heated to 1000 C High-eucryptite a d(A) 4.17 3.62 3.02 2.55 2.51 2.37 2.18 2.08 1.66 1.55 1.47 I/Io 100 13 16 39 8 6 13 5 6 6 9 hkl 111 200 220 311 222 331 422 d(A) 4.56 3.52 2.64 2.28 2.11 1.91 1.65 1.59 1.46 I/I1 11 100 4 3 3 11 5 1 3 hkl 100 102 110 200 202 006 212 300 206 Cubic a 7.221(1) A Hexagonal a 5.272(1) A c 11.431(1) A XAMs can also generally be characterised by a specific surface of less than 45 m 2 g 1 Preferably the specific surface is at least 0.1 m 2 g 1 more preferably at least 1 m 2 g', most preferably at least 5 m 2 g'1. Specific surfaces of 45m 2 g-1 or more are very unlikely to be achieved using solid state reaction processes unless very high specific surface reagents are used. Kaolin group minerals are the most preferred aluminosilicate reagents and do not have sufficiently high specific surfaces to produce XAMs by a solid state reaction process with specific surfaces of 45m 2 g' 1 or more.

M-XAM can be further characterised by its composition when it is dehydrated, that is, when it is free of adsorbed water. Its composition range is given by MlqSi.qO,sH 2

O

1 where M alkali, 0.0 p s 2.0, 0.0 s q 1.0, 1.5 r 5 3.0, and 0.0 5 s 0.1. It should be noted that this general formula does not account for minor amounts of WO 96/12674 PCT/AU95/00320 -16other elements being present in the XAM structure, e.g. Fe, Mg, or Ca, nor does it account for impurity minerals or compounds which are not integrated into the XAM structure, e.g. TiO 2 -anatase, SiO 2 -quartz.

The water identified in the empirical composition may be present as hydroxyl or bound water. Free water and adsorbed water, that is, water which can be removed by heating the M-XAM at 4001C for 16 hours, is not included in the composition.

Thermogravimetric analysis of M-XAM to 1000 *C is able to determine the amount of water present as hydroxyl or bound water, and selected data are presented in Table 2.

Composition analyses and derived formulae (corresponding to formula 1) of several M-XAMs are also given below in Table 2 with cross-references to the synthesis examples described hereinafter. It is believed that unreacted reagent anions which may be used in the synthesif of XAM, for example, carbonate, bicarbonate, nitrate, are also not integrated into the XAM structures, and it is for this reason that they are not included in the empirical compositions.

Table 2 Composition of XAMs* Weight as oxide impiied formula XAM Na 2 O MgO A-1 2 0 3 SiO 2

K

2 0 CaO TiC 2 Fe 2

O

3 p q r s K-XAM Example 1 0.7 K-XAM Example 2 1.3 Na-XAM Example 3 19.9 Na-XAM Exampi%. t LI 1. 1 KINa-XAM Example 7 11.8 K-XAM Example 8 0.5 Na-XAM Example 9 14.3 K-XAM Ex. 12 0.66 g 0.9 K'-XAM Ex. 12 0.49 g 0.9 K-XAM Ex. 12 0.33 g 1.1 Na-XAM Ex. 13 0.42 g 16.4 Na-XAM Ex. 14 131 g 24.1 Na-XAM Ex. 14 43.7 g 16.0 Na-XAM Ex.20 18.3 K-XAM Ex. 15 nitrate 1.1 K-XAM Ex. 15 acetate 0.9 Na-XAM Ex.16 nitrate 18.1 Na-XAM Ex.16 citrate 22.5 29.6 29.2 0.2 29.1 0.1 28.6 29.5 29.8 34.1 30.9 32.3 35.2 0.1 31.4 27.2 33.6 28.4 32.6 30.1 29.2 0.2 26.9 38.2 37.2 45.8 49.2 39.1 37.2 46.8 38.5 39.6 44.3 47.8 45.5 46.2 52.8 41.2 37.4 48.9 46.0 29.3 30.1 0.2 0.2 16.5 30.6 0.7 27.8 24.1 17.2 0.2 0.1 0.1 0.1 22.8 29.4 0.2 0.3 1.5 1.6 1.8 0.2 1.5 0.5 2.0 1.4 0.1 2.0 1.5 2.1 1.6 0.3 1.8 0.8 1.9 0.3 2.2 0.1 0.5 1.7 2.1 0.4 2.1 0.2 1.9 1.8 1.6 3.0 2.2 0.6 2.0 2.1 1.9 1.8 1.9 1.9 0.7 1.7 1.8 1.4 1.6 2.0 0.53 0.57 0.49 0.51 0.59 0.55 0.33 0.50 0.42 0.28 0.38 0.60 0.36 0.41 0.39 0.54 0.43 0.57 0.48 0.48 0.43 0.42 0.47 0.49 0.46 0.49 0.49 0.48 0.44 0.41 0.46 0.39 0.48 0.49 0.41 0.41 2.025 2.045 2.027 2.045 2.06 2.03 2_004 1.965 1.906 1.97 1 2.095 1.95 2.0 12 1.955 2.025 1.795 2.008 0.06 0.05 0.04 0.04 0.04 Determined using quantitative X-ray spectroscopy (EDS). Values not given indicate amount below detection limit.

Table 2 cont. Composition of XAMs* Weight ac oxideimlefoua implied formula

XAM

Na 2 O MgO A1 2 0 3 K-XAM Example 19 Na-XAM Example 19 Na-XAM Ex.21 2.0:1 Na-XAM Ex.2 1 0.2:1 K-XAM Example 17 Na-XAM Example 17 K-XAM Example 18 Na-XAM Example 18 1.2 25.5 10.8 11.1 1.15 12.6 1.2 11.4 28.4 36.3 59.3 12.9 2.6 11.7 3.6 9.9 14.2 0.2 8 SiO 2 28.7 38.3 30.2 75.8 58.6 70.2 63.8 77.6 SiO 2 47.3 46.6 28.5 21.8 K(20 CaO Ti0 2 Fe 2 0 3 p q r s 43.4 0.2 0.2 0.1 Z4.2 0.9 0.3 2.2 V. L 0.1 0.4 0.5 1.5 0.6 1.1 0.2 0.8 0.93 0.61 0.21 0.24 0.46 0.30 0.35 0.27 0.54 0.53 0.70 0.17 0.19 0.14 0.21 0.12 2.195 2.040 1.755 2.035 2.135 2.08 2.07 2.08 20.0 1.0 0.1

XAM

Li 2 Ot Na 2 O A1 2 0 3 Ti0 2 Fe 2 0 3 Rb 2 O CS 2 0 q r s Li-XAM Example 5 Li-XAM Examnle 6 Rb-XAM Example 10 Cs-XAM Example I11 10.6 1.9 36.2 10.9 1.3 37.3 22.8 1.4 15.9 46.0 56.3 0.47 0.49 0.50 0.60 0.47 0.49 0.46 0.46 2.00 2.00 2.02 2.07 0.02 Determined using quantitative X-ray spectroscopy (EDS). Values not given indicate amount below detection limit.

t Lithium contents assumed as charge balancing with aluminium in the eucryptite-related structure WO 96/12674 PCT/A 95/00320 19 Synthesis of XAM XAMs are prepared by a process in which an aluminosilicate, or a combination of aluminium oxide-containing and silicon oxide containing compounds, are reacted together with an alkali oxide-containing reagent. Preferably the reaction is a solid state reaction, and three such reaction processes for the synthesis of XAM are described generally below. However, aqueous reactions may also produce acceptable XAMs.

Eroces1 The first process involves solid state reaction of oxide-containing alkali salt and aluminium-containing phyllosilicates. The range of conditions for the successful formation of XAM by this process is dependent on the aluminium-containing phyllosilicate used.

While many oxide-containing alkali salts and all aluminium-containing phyllosilicates are suitable as starting materials for this process, we exemplify the process using alkali carbonate and kaolin group minerals, which are among the preferred starting materials.

In this first process the mole ratio of alkali carbonate (M 2

CO

3 to the kaolin group mineral (ASi 2 0 5

(OH)

4 is preferably from 0.05 to 2, and most preferably is in the range of 0.5 to 1.

Reaction is suitably carried out at an elevated temperature at atmospheric pressure for a sufficient period of time to enable conversion to XAM. Initially, the kaolin group mineral and alkali carbonate are intimately mixed then heated to between 300 and 750 C until all the kaolin group mineral has reacted. The preferred conditions for this process are 450 to 550 °C for a period of between 3 and 24 hours. The resultant solid contains XAM which is usually free of reaction byproducts, but may contain some unreacted M 2

CO

3 which can be removed by rinsing with cold water.

I I I WO 96/12674 PCT/AU95/00320 Process 2 The second process involves solid state reaction of alkali hydroxide and aluminiumcontaining phyllosilicates. The range of conditions for the successful formation of XAM by this process is dependent on the aluminium-containing phyllosilicate used.

We exemplify the second process using kaolin group minerals, which are among the preferred starting materials.

In this second process the mole ratio of alkali hydroxide (MOH) to the kaolin group mineral (Al 2 Si 2

O(OH)

4 is preferably from 0.1 to 4, and most preferably is in the range of 1.0 to Readtion is suitably carried out at an elevated temperature at atmospheric pressure for a sufficient period of time to enable conversion to XAM. Initially, the kaolin group mineral and alkali hydroxide are intimately mixed then heated to between 400 0 C and 750 0 C until all the kaolin group mineral has reacted. The preferred conditions for this process are 500 0 C to 550 0 C for a period of between 3 and 24 hours. The resultant solid contains XAM which is usually free of reaction byproducts, but may contain some unreacted MOHwhich can be removed by rinsing with cold water.

Process 3 The third process involves solid state reaction of reactive forms of silica and alumina with alkali oxide-containing reagent. We exemplify the third process using colloidal silica, aluminium nitrate nonahydrate and alkali carbonate (M 2

CO

3 M alkali).

In this third process, the mole ratios of colloidal silica SiO) to aluminium nitrate nonahydrate (AI(N0 3 3 ).9H 2 0) to alkali carbonate (M 2

CO

3 are typically 2:2:1, but can vary substantially from this within the composition range described earlier for XAM. It is possible to replace the colloidal silica by other forms of silica, such as soluble alkali silicate.

WO 96/12674 PCT/AU95/00320 -21 Reaction takes place by dissolving the aluminium nitrate nonahydrate and alkali carbonate in a small amount of water then adding the colloidal silica to the dissolved salts. The reaction mixture is homogenised then the water evaporated slowly, giving a gel. This gel is then further reacted at elevated temperature and atmospheric pressure for a sufficient period of time to enable conversion to XAM.

The gel is heated to between 300 °C and 750 °C until XAM is observable by XRD.

The preferred conditions for this process are 550 C to 650 C for a period of between 2 days and 6 hours. The resultant solid contains XAM which is free of starting materials and is usually free of reaction byproducts.

Ernmples of specific conditions of synthesis.

Examples of the specific conditions of synthesis under which the components react together to give XAM are given below.

1. A mixture containing 2.6 g of kaolinite from Weipa, Australia, and 1.6 g of

K

2

CO

3 was dispersed in a small amount of distilled water to give a thick slurry.

The slurry was dried at 50 then heated at 500 "C in a platinum vessel for 16 hours. The reaction products were then thoroughly rinsed with distilled water to remove excess K 2

CO

3 then dried at 100 The dried reaction products weighed 2.7 g and comprised single phase K-XAM. The XRD profile for this material as prepared is shown in Figure 2. 2 kg of kaolinite from Skardon River, Australia, was dispersed in 4.7 litres of water. A solution containing 0.92 kg of commercial grade K 2

CO

3 in 3.5 litres of water was slowly added, and the resultant slurry was stirred vigorously for minutes. This slurry was dehydrated using a spray drier with an inlet temperature of 250 C. The spray dried reaction mixture was heated at 500"C for 3.5 hours.

Excess K 2 C0 3 was removed by repeated rinsing with water until the pH of the elute dropped to 9. The BET surface area of this material was 7.86 m 2 The XRD profile of this material as prepared is shown in Figure 6.

WO 96/12674 PCT/AU95/00320 -22- 3. A mixture containing 10.24 g of kaolinite from Weipa, Australia, and 4.24 g of Na 2

CO

3 was dispersed with 10 ml of distilled water to give a slurry. The slurry was partially dried at 50 then heated at 600 0 C in an alumina vessel for 16 hours.

The resultant dry reaction product was remixed with water, again partly dried, then heated at 600 C for 7 hours. The reaction product was thoroughly rinsed with distilled water to remove excess Na 2

CO

3 then dried at 100 The dried reaction products weighed 9.0 g and comprised single phase Na-XAM. The XRD profile for this material is shown in Figure 4. 1 kg of kaolinite from Skardon River, Australia, was dispersed in 2.33 litres of water. A solution containing 0.365 kg of commercial grade NaCO 3 in 1 litre of water was slowly added and the resultant slurry was stirred vigorously for minutes. This slurry was dehydrated using a spray drier with an inlet temperature of 250 The spray dried reaction mixture was heated at 500 C for 3.5 hours.

Excess Na 2

CO

3 was removed by repeated rinsing with water until the pH of the elute dropped to 9. The BET surface area of this material was 24.50 m 2 The XRD profile of this material as prepared is shown in Figure 7.

A mixture containing 2.5 g of kaolinite from Skardon River, Australia, and 0.7 g of AR grade Li 2

CO

3 was dispersed in a small amount of distilled water to give a thick slurry. The slurry was dried at 100 then heated at 460 *C in an alumina vessel for 16 hours. The reaction product was remixed with water to give a thick slurry, dehydrated at 100 C then heated again at 460 C for 3.5 hours. These reaction products were throroughly rinsed with distilled water to remove excess Li 2

CO

3 then dried at 100*C. The dried reaction products weighed 2.0 g and comprised single phase Li-XAM. The XRD profile for this material as prepared is shown in Figure 8.

6. 200g of kaolinite from Skardon River, Australia, was dispersed in 470 ml of water. A solution containing 134 g of AR grade lithium acetate dihydrate in 350 ml of water was slowly added and the resultant slurry was stirred vigorously for minutes. This slurry was dehydrated using a spray drier with an inlet temperature

I

WO 96/12674 PCIT/AU95/00320 -23of 250 The spray dried reaction mixture was heated at 500 C for 16 hours.

Excess lithium acetate was removed by repeated rinsing with water until the pH of the elute dropped to 9. The XRD profile of this material as prepared is shown in Figure 8.

7. 200g of kaolinite from Skardon River, Australia, was dispersed in 472 ml of water. A solution containing 36.5 g of commercial grade Na 2

CO

3 and 46 g of commercial grade K 2

CO

3 in 350 ml of water was slowly added and the resultant slurry was stirred vigorously for 20 minutes. This slurry was dehydrated using a spray drier with an inlet temperature of 250 The spray dried reaction mixture was heated at 500 *C for 3 hours. Excess Na 2

CO

3 and K 2

CO

3 were removed by repeated rinsing with water until the pH of the elute dropped to 9. The XRD profile of this material as prepared is shown in Figure 9.

8. 1.28 g of kaolinite from Weipa, Australia, was thoroughly dry mixed with 0.5 g of finely powdered KOH. The mixture was heated in a platinum vessel at 500 *C for 16 hours. The reaction products were thoroughly rinsed with distilled water to remove excess KOH, then dried at 100 C. The dried reacton products weighed 1.20 g and comprised single phase K-XAM. The XRD profile for this material as prepared is shown in Figure 11.

9. 1.28 g of kaolinite from Weipa, Australia, was thoroughly dry mixed with 0.4 g of finely powdered NaOH. The mixture was heated in a platinum vessel at 500 C for 16 hours. The reaction products were thoroughly rinsed with distilled water to remove excess NaOH, then dried at 100 The dried reaction products weighed 1.1 g and comprised single phase Na-XAM. The XRD profile for this material as prepared is shown in Figure 11.

A mixture containing 2.5 g of kaolinite from Skardon River, Australia, and 2.3 g of AR grade Rb 2 C03 was dispersed in a small amount of distilled water to give a thick slurry. The slurry was dried at 100 *C then heated at 460 °C in an alumina vessel for 16 hours. The reaction products were thoroughly rinsed with distilled WO 96/12674 PCT/AU95/00320 24water to remove excess Rb 2

CO

3 then dried at 100 The dried reaction products weighed 3.15 g and comprised single phase Rb-XAM. The XRD profile for this material as prepared is shown in Figure 8.

11. A mixture containing 2.5 g of kaolinite from Skardon River, Australia, and g of AR grade Cs 2

CO

3 was dispersed in a small amount of distilled water to give a thick slurry. The slurry was dried at 100 then heated at 460 °C in an alumina vessel for 16 hours. The reaction products were thoroughly rinsed with distilled water to remove excess Cs 2

CO

3 then dried at 100 The dried reaction products weighed 4.18 g and comprised single phase Cs-XAM. The XRD profile for this material as prepared is shown in Figure 8.

12. Four separate mixtures containing 1.28 g of kaolinite from Skardon River, Australia, and 0.85, 0.66, 0.49 and 0.33 g, respectively, of K 2

CO

3 wei each dispersed in a small amount of distilled water to give a thick slurry. The slurries were dried at 50 0 C, then heated at 500 C in alumina vessels for 16 hours. The reaction products were thoroughly rinsed with distilled water to remove excess

K

2

CO

3 then dried at 100 OC. The dried reaction products weighed 1.59, 1.32, 1.31 and 1.2 g, respectively, and comprised single phase K-XAM. The XRD profiles for three of these as-prepared materials are shown in Figure 13. Two separate mixtures containing 5.12 g of kaolinite from Skardon River, Australia, and 2.12 g of commercial grade Na2CO 3 and 1.28 g of the same kaolinite and 0.42 g of Na2CO 3 were each dispersed in a small amount of distilled water to give a thick slurry. The slurries were dried at 100 0 C, then heated at 600 C in alumina vessels for 16 hours. The reaction products were then thoroughly rinsed with distilled water to remove excess Na 2

CO

3 then dried at 100 0

C.

14. Two separate spray dried reaction mixtures were prepared at different mole ratios. Two aliquots of 200 g of kaolinite from Skardon River, Australia, were each dispersed in 492 ml of water. Solutions containing 43.7 g of commercial grade Na 2

CO

3 in 125 ml of water and 131 g of commercial grade Na 2

CO

3 in 500 ml of hot WO 96/12674 PC'ITAU95/00320 water were slowly added and the resultant slurries were stirred vigorously for minutes. These slurries were dehydrated using a spray drier with an inlet temperature of 250 The spray dried reaction mixture was heated at 500 *C for hours. Excess Na 2

CO

3 was removed in each case by repeated rinsing with water until the pH of the elute dropped to The XRD profiles of the respective materials as prepared are shown in Figure Two separate mixtures containing 1.28 g of kaolinite from Skardon River, Australia, and 1.0 g of KNO 3 and 1.0 g of potassium acetate were dispersed in a small amounts of distilled water to give thick slurries. The slurries were dried at 100 C, then heated at 450 C in alumina vessesl for 16 hours. The reaction products were thoroughly rinsed with distilled water to remove excess potassium salt then dried at 100 The dried reaction products each weighed 1.3 g. The nitrate and acetate products comprise single phase K-XAM. The XRD profiles for these materials are shown in Figure 11.

16. Two separate mixtures containing 2.56 g of kaolinite from Skardon River, Australia, and 1.7 g of NaNO 3 and 2.0 g of sodium citrate were dispersed in a small amount of distilled water to give thick slurries. The slurries were dried at 100 *C, then heated at 450 *C in alumina vessesl for 16 hours. The reacton products were thoroughly rinsed with distilled water to remove excess sodium salt, then dried at 100 C. The dried reaction products weighed 2.02 and 2.2 g respectively. The nitrate and citrate products comprise single phase Na-XAM. The XRD profiles for these materials are shown in Figure 11.

17. Two separate mixtures containing 1.00 g of montmorillonite from Texas, USA, and 0.41 g of K 2

CO

3 and 0.27 g of Na 2

CO

3 were dispersed in a small amount of distilled water to give slurries. The slurries were partially dried at 50 0 C, then heated at 600 "C in an alumina vessel for 16 hours. The resultant potassium dry reaction products were remixed with water, again partly dried, then heated at 600 *C for 16 hours. Both reaction products were thoroughly rinsed with distilled water to remove excess K 2 C0 3 and Na 2

CO

3 then dried at 100 C. The dried WO 96/12674 PICT/AU95/00320 -26reaction products weighed 0.88 and 0.75 g respectively. The XRD profiles for these materials are shown in Figure 12.

18. Two separate mixtures containing 1.00 g of pyrophyllite and 0.46 g of K2CO, and 0.30 g of Na 2

CO

3 were dispersed in a small amount of distilled water to give slurries. The slurries were partially dried at 50 then heated at 600 *C in an alumina vessel for 16 hours. The resultant sodium dry reaction products were remixed with water, again partly dried, then heated at 600 *C for 16 Lours. Both reaction products were thoroughly rinsed with distilled water to remove excess

K

2 C0 3 and Na 2

CO

3 then dried at 100 C. The dried reaction products weighed 0.85, 0.67 g respectively. The XRD profiles for these materials are shown in Figure 13.

19. To 5 ml of distilled water were added 3.75 g of aluminium nitrate nonahydrate and 0.53 g of anhydrous sodium carbonate or 0.825 g of potassium carbonate hydrate. 1.58 g of Ludox AM (du Pont) colloidal silica was added to this solution and stirred for 30 minutes. The resultant solution was evaporated to dryness at 100*C in a platinum crucible, then heated at 500"C for 16 hours. The dried reaction product was poorly crystalline single phase Na-XAM or K-XAM, depending on the carbonate used. The XRD profiles for these reaction products are shown in Figure 14.

A mixture containing 2.56 g of halloysite from Mataura Bay, New Zealand, and 1.04 g of commercial grade Na 2

CO

3 was dispersed in a small amount of distilled water to give a thick slurry. The slurry was dried at 100 then heated at 460 "C in an alumina vessel for 16 hours. The reaction product was remixed with water to give a thick slurry, dehydrated at 100 then heated again at 460 *C for 3.5 hours.

The reaction products were thoroughly rinsed with distilled water to remove excess Na 2

CO

3 then dried at 100 *C.

The dried reaction products weighed 1.8 g and comprised single phase Na-XAM.

The XRD profile for this material is shown in Figure 9.

WO 96/12674 IPCT/AU95/00320 -27- 21. Two extreme compositions of Na-XAM were prepared as follows.

To give an Al:Si ratio of 0.2:1.0, 5 ml of distilled water were added to 1.875 g of aluminium nitrate nonahydrate and 0.265 g of anhydrous sodium carbonate. 3.9 g of Ludox AM (du Pont) colloidal silica was added to this solution and stirred for minutes. The resultant solution was evaporated to dryness at 100 C in a platinum crucible, then heated at 500 *C for 16 hours. The dried reaction product weighed 1.32 g and was single phase Na-XAM.

To give a AI:Si ratio of 2.0:1.0, 5 ml of distilled water were added to 3.7 g of aluminium nitrate nonahydrate and 0.53 g of anhydrous sodium carbonate. 0.8 g of Ludox AM (du Pont) colloidal silica was added to this solution and stirred for minutes. The resultant solution was evaporated to dryness at 100 C in a platinum crucible, then heated at 500 "C for 16 hours. The dried reaction product weighed 0.7 g and was single phase Na-XAM. The XRD profiles for these reaction products are shown in Figure Properties of XAM In XAM it is possible to exchange, at least partly, the alkali metal cation with any cation which is stable in aqueous solution. Such exchange cations include other alkali metal cations, alkaline earth cations, transition metal cations, lanthanide and actinide cations, other metal cations and ammonium. There are many transition metal cations Co 2 Ni 2 Cu 2 Fe 2 lanthanide cations La 3 other metal cations Pb 2 Cd2+, Zn 2 and actinide cations UO2 2 which show high levels of cation exchange for XAM prepared under certain conditions.

However, the extent of exchangeability of cations depends on the method of preparation of XAM and the conditions of the exchange reaction, such as temperature, time and concentration of exchange solution.

Table 3 lists the percent cation exchange for a selection of cations for a range of XAMs. Cation exchange was performed using concentrated solutions (typically WO 96/12674 PCT/AU95/00320 -28- 5M) of the relevant soluble salt, exept for U022' which used a 0.33 M uranyl nitrate solution and La 3 which used a 0.65 M solution.

Table 3 Cation exchange capacity* (CEC) derived from replacement of alkali metal§ in selected XAMs K-XAM Example 1 K-XAM Example 2 Na-XAM Example 3 Na-XAM Example 4 Weight percent as K-XAM Example 2 Na-XAM Example 4 Cu 2 395 542 492 503 Cd 2 Pb 2 Mg9 2 Zn 2 Ca 2 La 3 U0 2 2 Fe 3 Ni> CGo+

NH

4 426 528 550 269 176 443 200 420 229 381 565 319 588 479 409 551 465 559 289 oxide of Cu2> 48.3 39.3 exchange Cd 2 8-7 7.6 cationt Pb 2 28.5 34.8 for a range of cations Mg2> Zn 2 Ca 2 8.0 39.1 3.5 8.3 31.6 3.9 La 3 10.0 9.8 U0 2 2 21.9 22.8 Fe 3 4.3 5.2 Ni 2 31.0 40.0 C0o+ 33.5 33.1 milliequivalents per 100 g determined as percent removal of alkali cation reduction of alkali metal determined by X-ray spectroscopy (EDS) t exchange cation content determined by X-ray spectroscopy (EDS) WO 96/12674 PCTIAU95/00320 In aqueous suspension, XAM has a particular affinity to certain cations. The cations include the alkaline earths Mg 2 Sr 2 and Ca 2 the transition metals Cu2+ Ni 2

CO

2 Ag, Fe 2 Cr and Mn 2 the other metal cations Al Zn 2 Cd 2 Pb 2 and Hg 2 the lanthanide Nd 3 and the actinide-containing cation UO 2 It is expected that XAM will also have affinity to other aqueous cations with similar size, shape and charge to those listed above. Also, due to the similar chemical behaviour of trivalent lanthanides it is assumed that the properties demonstrated for Nd 3 will apply to all trivalent lanthanides, including Y 3 The affinity of XAM for these cations has been demonstrated by measuring the percent uptake of each of these cations from a solution containing a low concentration (10-100 ppm) of the subject cation and a relatively high concentration of Na (0.1 The details of selectivity experiments together with their results are given in Table 4. The level of selectivity of XAM towards these cations is relatively independent of temperature but the rate of exchange is significantly enhanced by increase in temperature.

For the purposes of this invention, to identify those cations for which M-XAM (M alkali metal) is highly selective in aqueous solution, we arbitrarily define high selectivity as removing 290% of that cation from a solution containing 0.1 M Na as background. We define M-XAM as being selective when 10% of that cation is removed under the same conditions.

Table 4 Selectivity results removed) for a selection of XAMs for various cations Cu 2 Cd 2 Pb 2 Mg 2 Zn 2 Ca2+ pH 6.5 5.0 4.5 6.5 6.5 Concentration (ppm) 100 10 20 10 10 K-XAM Example 1 99.9 Na-XAM Example 3 99.8 64.4 95.1 86.3 93.6 97.0 Unless otherwise indicated 25 ml of solution is treated with 0.09 g of XAM overnight at room temperature. All solutions contain a background of 0.1 M Na+.

All cation concentrations measured by atomic absorption spectroscopy (AAS) C Cu 2 Cd 2 Pb 2 Hg 2 Zn 2 Ca 2 Ca2+ Mg 2 pH 6.5 3.5 3.5 1.5 6.5 6.5 6.5 Concentration (ppm) 100 100 100 100 100 100 20 m K-XAM Example 1 94.3 81.9 100.0 99.6 28.3 51.1 m K-XAM Example 2 >99.99 97.5 100.0 81.3 99.9 45.1 >99.5 32.2 3Na-XAM Example 3 99.99 44.0 100.0 84.2 56.5 28.2

C

r Na-XAM Example 4 99.99 84.1 100.0 60.0 98.4 50.3 >99.5 21.0 Li-XAM Example 5 98.2 80.2 98.0 99.8 44.6 42.4 Li-XAM Example 6 99.35 82.5 99.7 100.0 36.2 44.7 Na/K-XAM Example 7 99.98 100.0 99.8 100.0 39.8 6.6 Unless otherwise indicated 100 ml of solution is treated with 1 g of XAM for 15 minutes at room temperature. All solutions contain a background of 0.1 MNa except for Ca 2 Cu 2 and Ca 2 concentrations measured by ion selective electrodes, all other cation concentrations measured by atomic absorption spectroscopy (AAS) Table 4 continued.

Cu 2 and Pb 2 selectivity for other XAMs (percent removed) Example

XAM

Reagent /weight 8 9 10 11 K-XAM Na-XAM Rb-XAM Cs-XAM 12

K-XAM

0.66 g 12

K-XAM

0.49 g 12

K-NAM

0.33 g 13 Na-XAM 0.42 14 Na-XAM 131 g 14 Na-XAM 43.7 g Cu 2 Pb 2 97.2 99.99 99.99 99.99 99.7 95.8 60. 5 90.6 99.99 79.2 99.8 98.7 99.8 99.7 99.8 98.8 46.1 99.7 99.9 99.5 Example

XAM

Reagent/weight Cu 2 Pb 2 Example

XAM

Reagent/weight 15

K-XAM

nitrate 15

K-XAM

acetate 16 Na-XAM nitrate 16 17 17 Na-XAM K-XAM Na-XAM citrate mont. mont.

18

K-XAM

pyroph.

18 Na-XAM pyroph.

K-XAM Na-XAM 98.05 99.99 96.6 99.99 99.4 99.99 99.99 64.5 99.98 79.6 100.0 99.9 100.0 99.6 99.5 99.7 99.8 99.7 99.8 99.4 20 Na-XAM halloysite 21

K-XAM

2.0:1.0 21 Na-XAM 0.2:1.0 2

K-XAM

1000 0

C

2

K-XAM

1 200 0

C

N4 4 NXAM Na-XAM 1000 0 C 1200 0

C

Cu 2 Pb 2 98.34 99.99 99.6 19.0 0.0 10.7 99.9 99.6 99.1 21.0 0-0 For all analyses 100 mld of solution is treated with 1 g of XAM for 15 minutes at room temperature. All solutions contain a background of 0. 1 M Na:+.

Cu 2 concentrations measured by ion selective electrode. Pb 2 concentrations measured by atomic absorption spectroscopy (AAS).

Table 4 continued.

Ni 2 Co 2 Ag+ Fe 2 Cr 3 Mn 2 Sr 2 A1 3 Nd 3 U0 2 U02 pH 5.5 5.5 4.0 5 4.5 5.5 6.0 4.5 4.5 Concentration (ppm) 100 100 100 100 100 100 100 100 5230 2390z K-XAM Example 2 100.0 99.55 99.66 99.92 100.0 79.63 67.49 98.68 25 31 Na-XAM4Example 4 89.75 90.70 99.79 99.95 100.0 60.75 58.76 99.68 25 29 Li-XAM Example 6 66.90 80.70 99.79 94.66 99.35 54.02 45.92 80.38 15 16 Unless otherwise indicated 100 ml] of solution is treated with 1 g of XAM for 15 minutes at room temperature. All solutions contain a background of 0. 1 M Nat.

All cation concentrations measured by atomic absorption spectroscopy (AAS) except for Nd 3 and U0 2 2 which are determined by UV/visible spectroscopy.

lt

W,

N31 (i/12744 I 'A L 9.i(U2O -34- Applications of XAM The high CEC which XAM displays and its high selectivity to a number of aqueous cations makes XAM potentially useful in the treatment of industrial and mine waste water, as well as in the remediation of contaminated environmental waters. In particular, its high selectivity to aqueous Cu 2 Zn 2 Cd2+, and Pb2+ all of which are toxic and environmentally problematic, make XAM particularly useful for such applications. It is probable the XAM will also sequester these cations from nonaqueous solvents or from liquid mixtures containing such non-aqueous solvents, such 10 as wine.

e*.

XAM is also potentially suitable for application as a detergent builder or water softener as it shows a capability to sequester Ca 2 and Mg 2 from solution.

t* "L The potentially high CEC of XAM enables high loading levels of various cations.

These highly exchanged XAMs may have application in the delivery of these cations in pharmaceuticals, stock feed, horticulture and agriculture.

XAMs which have been highly exchanged by transition metals or lanthanides are likely to have potential usage as heterogeneous catalysts.

*a Whilst the above has been given by way of illustrative example of the invention, many modifications and variations may be made thereto by persons skilled in the art without departing from the broad scope and ambit of the invention as herein set forth.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (4)

1. A poorly or partly crystalline alkali metal aluminosilicate material having a stuffed silica polymorph related-structure in which the aluminium is at least predominantly tetrahedrally coordinated and a cation exchange capacity at room temperature of at least 1 meq 100g 1 in aqueous solution, which is produced by reacting an aluminosilicate, or a combination of aluminium oxide-containing and silicon oxide-containing compounds, with an alkali oxide-containing reagent. 10 2. A material according to claim 1 having a BET surface area of at least 0.1, preferably at least 1, more preferably at least 5 m g g, and less than 45 mg' 1

3. A material according to claim 1 or claim 2 wherein said cation exchange capacity is at least 10 meq 100g 1

4. A materials according to claim 3 wherein said cation exchange capacity is in the range

50-750 meq 100g 1 A material according to any one of claims 1 to 4 wherein said interstitial sites of the 20 structure are occupied by two or more cations of which at least one is alkali metal. 6. A materials according to any one of the preceding claims which in a pure, dehydrated form has the composition MpAl 1 Si .qOr.sH2O where M alkali metal, 0.0 p 2.0, 0.0 q 1.0, 105 r 3.0 and 0.0 s 0.1. 7. A material according to any one of the preceding claims wherein the alkali cation can be exchanged partly or ful' by one or more cations selected from the group comprising: the alkalis Li+, Na+, Rb+, Cs+; ammonium NH 4 the alkaline earths Ca 2 Mg 2 Sr 2 the transmition metals Cr 3 Mn 2 Fe 2 Fe 3 Ag" 2 Cu 2 Ni 2 Co 2 the other metals 3 Al 3 Zn 2 Cd 2 Pb 2 and, Hg 2 the lanthanides Nd 3 and Ln 3 and the uranyl UO z .2 P R 36 8. A material according to claim 7 which is highly selective in its cation exchange towards one or more of the aqueous cations selected from the group comprising Ca 2 Al 3 Cu" 2 Ni 2 Co 2 Ag+, Fe 2 Cr3, Zn,+ Cd2+ and Pb 2 9. A material according to claim 7 which is selective in its cation exchange towards the aqueous cations Ca", Mg", Sr 2 A13, Cu 2 Ni 2 Co", Ag+, Fe 2 Cr 3 Mn,2+ Zn2+, Cd+, Pb 2 Hg z Nd 3 Ln 3 and UO, 2 A product comprising material according to claim 7 which has been subjected to 10 partial or full exchange of the alkali metal cation by at least one cation selected from the group comprising: the alkalis Li+, Na K- Rb Cs+; ammonium NIH 4 the alkaline earths Ca 2 Mg Sr 2 the transition metals Cr 3 Mn 2 Fe 2 Fe3, Ag+, Cu", Ni 2 Co2+; the other metals Al3+, Zn1 Cd 2 Pb2+ and the lanthanides Nd3+ and Ln 3 and the uranyl UOz 2 11. A material according to claim 1 or a product according to claim 10 and substantially as herin described with reference to the Examples. 12. Use of a material or product according to any one of claims 1 to 11 in cation 20 exchange. 66 13. Use of a material according to claim 9 which is selective in its cation exchange towards the aqueous cations Ca- and Mg 2 as a water softener or detergent builder. 14. Use of a product according to claim 10 for the delivery of a cation in a pharmaceutical, stock feed, horticulture and agriculture. Use of a product according to claim 10 as a heterogenous catalyst. -3.O 16. A process for the preparation of a poorly or partly crystalline alkali metal i 1 'Ii 1 1 l 'M 1 .11 -37- aluminosilicate material having a stuffed silica polymorph related-structure in which the aluminium is at least predominantly tetrahedrally coordinated and a cation exchange capacity at room temperature of at least 1 meq 100g 1 in aqueous solution, in which an aluminosilicate, or a combination of aluminium oxide-containing and silicon oxide-containing compounds, are reacted together with an alkali oxide-containing reagent. 17. A process according to claim 16 which is performed at a temperature of 750°C or less. I 10 18. A process according to claim 17 wherein the reaction is performed at a temperature in the range of 300 to 750 0 C. 19. A process according to any one of claims 16 to 18 wherein the alkali oxide containing reagent decomposes in air at a temperature below 1000°C to give alkali oxide. 20. A process according to claim 19 wherein the alkali oxide-containing reagent is a carbonate or hydroxide. 99 21. A process according to claim 19 wherein the alkali oxide-containing reagent is a bicarbonate, nitrate or carboxylate. 9 *9 22. A process according to any one of claims 16 to 21 wherein the aluminosilicate is a phyllosilicate. 23. A process according to claim 22 wherein the phyllosilicate is a kaolin group mineral. 24. A process according to claim 22 wherein the phyllosilicate is montmorillonite or pyrophyllite. f i H P "Al 'sS710 "ME 24 I$J 26. A process according to claimn 16 and substantially as herein described wvith reference to the Examples. DATED this TWENTY FOURTH day of FEBRUARY, 1999 Australian National University DAVIES COLLISON CAVE Patent Attorneys for the Applicant *O* e *.e a. e 9~ a a a. a o a. 0 a a a a a. a a a. 7. 1.