Co-synthesis of layered minerals and metal particles and products obtained therefrom

Abstract

The present invention relates to a method for producing a mixture containing a precious metal and a layered mineral, and to a composition obtained from said method. [Selected Figure] Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a particulate mixture comprising particles of at least one layered mineral and particles of at least one precious metal, said precious metal particles being intimately bound to said layered mineral particles. The present invention also relates to products obtained from said method and their uses. [Background technology]

[0002] A phyllomineral ("sheet mineral") is a mineral having a crystal structure containing at least one tetrahedral layer and at least one octahedral layer. A phyllosilicate (or "sheet silicate") is a naturally occurring layered mineral composed of stacks of parallel sheets composed of tetrahedral and octahedral layers, forming silicate parallel sheets of silicate tetrahedra. Examples of natural phyllosilicates are talc, mica, chlorite, kaolinite, among others. Phyllosilicates may also be artificially prepared. As used herein, the term "layered mineral" encompasses natural and synthetic phyllosilicates, specifically including talc, mica, chlorite, kaolinite, and the like. Layered minerals and phyllosilicates have many industrial applications: in the form of small particles they may be used, for example, as fillers in thermoplastics, elastomers, paper, paints, lacquers, textiles, metallurgy, pharmaceuticals, cosmetics, phytosanitary preparations, plant protection products or fertilizers, where they are used as inert or functional fillers. WO 2013 / 004979 A1 discloses a synthesis procedure for producing layered minerals and phyllosilicates such as talc in a batch process. WO 2015 / 159006 A1 discloses a continuous process for producing layered minerals and phyllosilicates such as talc, mica or montmorillonite. A general problem of all prior art methods for the artificial production of layered minerals or phyllosilicates is the tendency of the resulting fine particles to agglomerate or cake, which leads to difficulties when applying said synthetic particles, for example when putting them into suspension. The prior art therefore constitutes a problem. Summary of the Invention

[0003] The invention is defined in the appended claims. In particular, the invention is embodied by a method comprising the steps of providing a layered mineral source, providing a precious metal source, combining the pre-prepared layered mineral source with the pre-prepared precious metal source, and optionally hydrothermally treating the resulting mixture. It has been found that the above method can result in a particulate composition in which precious metal nanoparticles are intimately bound to the surfaces of the layered mineral particles, in particular on the edge surfaces of the layered mineral particles. According to one embodiment of the invention, the method can use as the source of the layered mineral a layered mineral precursor or an actual layered mineral, or a mixture of a layered mineral precursor and an actual layered mineral. According to one embodiment of the invention, the layered mineral is a non-swelling layered mineral. Similarly, according to a further embodiment of the invention, the method can use as the source of the precious metal a precious metal precursor such as a precious metal salt, or as the source of the precious metal an actual precious metal in metallic state, or a mixture of a precious metal precursor and an actual precious metal in metallic state. It has been found that the method according to the invention is versatile enough that the layered mineral and / or the precious metal forming part of the product can be formed in situ from suitable precursors or they can already be prepared in their desired form as a layered mineral and / or a precious metal in metallic state, respectively. This versatility gives the user great flexibility depending on the availability of raw materials and laboratory equipment.

[0004] According to a further embodiment of the present invention, the layered mineral may be a single layered mineral or a mixture of different layered minerals. For example, the layered mineral source may be talc or a talc source, or mica or a mica source, or a mixture of talc and mica, or a mixture of talc and mica sources ... According to one embodiment of the invention, the layered mineral may be selected from talc, mica, kaolinite, chlorite or mixtures thereof. According to a further embodiment of the invention, the precious metal may be selected from gold, platinum, palladium, ruthenium, rhodium, iridium, osmium, silver or mixtures thereof. According to certain embodiments, the method of the invention may involve the use of a talc precursor and / or a gold salt. According to one of these embodiments, the layered mineral source may be (i) a talc precursor in the form of an aqueous solution containing a soluble metasilicate and / or metagermanate, optionally in combination with a carboxylate, and (ii) a talc precursor in the form of an aqueous solution containing a soluble metal salt. According to a further one of these embodiments, the precious metal source may be a precursor of metallic gold in the form of an aqueous solution containing a soluble gold salt. Such a combination has been found to be particularly well suited for the present invention.

[0005] According to one of the above-mentioned embodiments, the soluble metasilicic acid and / or the soluble metagermanate may be selected from the respective sodium or potassium salts, or mixtures thereof. According to a further one of the above-mentioned embodiments, the optional carboxylate is a metal carboxylate, the metal of which is selected from sodium or potassium, or mixtures thereof. The carboxylate may be selected from formate, acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, or mixtures thereof. Furthermore, the metal in the soluble metal salt of (ii) in the layered mineral source may be a divalent metal selected from magnesium, cobalt, zinc, copper, manganese, iron, nickel, chromium, or mixtures thereof. The metal salt may be selected from metal salts capable of reacting with metasilicic acid or metagermanate to form a synthetic layered mineral precursor. In the particulate, the metal salt may be selected from metal salts soluble in a liquid medium such as water, such as dicarboxylate, sulfate, nitrate, chloride, etc. According to a further embodiment, the precious metal in said soluble precious metal salt may be selected from gold, palladium, platinum, iridium, rhodium, ruthenium, osmium, silver or mixtures thereof. These have been found to be particularly suitable conditions for the process of the invention.

[0006] According to a further embodiment of the invention, the step of combining the pre-prepared layered mineral source with the pre-prepared precious metal source may be performed by mixing the pre-prepared layered mineral source with the components of the layered mineral source in a desired order. For example, the components of the layered mineral source may be mixed first and then the pre-prepared precious metal source may be added. For example, the components of the layered mineral source (i) may be mixed first with the pre-prepared precious metal source and then the pre-prepared precious metal source component (ii) may be added. For example, the components of the layered mineral source (ii) may be mixed first with the pre-prepared precious metal source and then the pre-prepared precious metal source component (i) may be added. For example, the components of the layered mineral source and the pre-prepared precious metal source may be mixed simultaneously. It has been found that simple mixing is sufficient for the method according to the invention. According to a further embodiment of the invention, the optional hydrothermal treatment, if carried out, may be carried out by heating at a temperature between 100°C and 600°C for a duration between 10 minutes and 30 days. According to one embodiment, the temperature of the heat treatment may be between 150°C and 400°C, or between 150°C and 370°C, or between 200°C and 350°C. According to one embodiment, the duration of the heat treatment may be between 30 minutes and 15 days, or between 1 hour and 24 hours, or between 2 hours and 12 hours. According to one embodiment, this heating may be achieved by microwave heating, convection heating, or a combination thereof. It has been found that the optional hydrothermal treatment may or may not be necessary to achieve the desired product by the method of the invention. Depending on the reactants selected, the hydrothermal treatment may have to be more or less severe, by adapting the temperature and duration according to the knowledge of the person skilled in the art. According to some embodiments, as set forth in WO 2015 / 159006 A1, the optional hydrothermal treatment may be carried out as a batch process in an autoclave under autogenous pressure or as a continuous process under pressures of 1 MPa or higher.

[0007] According to one embodiment of the invention, prior to the hydrothermal treatment, a further step may be included in which a carboxylate R-COOM', where M' is Na or K and R is H or alkyl with less than 10 carbon atoms, is added as disclosed in WO 2012 / 085239 A1. According to a further embodiment of the invention, the product obtained after the mixing step or after the hydrothermal treatment step, if performed, may be dried, washed and / or centrifuged in order to obtain a final product with suitable storage, transport and durability properties. According to the invention, it has been found that the particulate product obtained has a reduced tendency to agglomerate or cake. This makes the drying, washing and / or centrifugation requirements more flexible, since according to the prior art, the particulate product often agglomerates or adheres at this stage. Also part of the invention is a particulate composition obtainable by the method of the invention. The particulate composition obtained comprises a combination of layered minerals and precious metals, the precious metals being in the form of nanoparticles intimately bound to the surface of the phyllosilicate particles. In the particulate composition according to the invention, the precious metal nanoparticles are perhaps preferably bound to the edges of the layered mineral platelets, i.e., to the narrow ends of the platelet particles, rather than to larger planar surfaces. According to some embodiments of the invention, depending on the selection of the layered mineral(s) and precious metal(s) used in the method according to the invention, the particulate composition may comprise, as the layered mineral, talc, mica, kaolinite, chlorite or mixtures thereof, and as the precious metal, gold, iridium, platinum, palladium, ruthenium, rhodium, osmium, silver or mixtures thereof. For example, according to some embodiments of the invention, the precious metal may be a mixture of gold and platinum, or a mixture of gold and palladium, or a mixture of rhodium, platinum and palladium. In one particular embodiment of the invention, the particulate composition comprises talc particles having gold nanoparticles bound to the surface of the talc platelets on or near the platelet edges.

[0008] According to some embodiments of the invention, the particulate composition comprises layered mineral platelets having a diameter along their longest axis of 10 nm to 1 mm as measured by Field Emission Gun Scanning Electron Microscopy (FEG-SEM) or Transmission Electron Microscopy (TEM). For example, the layered mineral platelets may have a diameter along their longest axis of 25 nm to 1 mm, or 50 nm to 10,000 nm, such as 100 nm to 1000 nm or 200 nm to 750 nm, such as about 100 nm, or about 150 nm, or about 200 nm, or about 250 nm, or about 300 nm, or about 350 nm, or about 400 nm, or about 450 nm, or about 500 nm, or about 550 nm, or about 600 nm, or about 650 nm, or about 700 nm, or about 750 nm, or about 800 nm, or about 850 nm, or about 900 nm, or about 950 nm, or about 1000 nm. According to some embodiments of the present invention, the granular composition comprises precious metal particles having an average particle size in the range of 1 nm to 100 nm, as measured according to FEG-SEM or TEM. For example, the average particle size of the precious metal particles may be 2 nm to 50 nm, or 3 nm to 30 nm, such as 4 nm to 20 nm or 5 nm to 15 nm, such as about 5 nm, or about 6 nm, or about 7.5 nm, or about 10 nm, or about 12.5 nm, or about 15 nm, or about 20 nm.

[0009] Finally, according to a further embodiment of the present invention, the method of the present invention and the particulate composition of the present invention can be used in the manufacture of catalysts, cosmetics, pharmaceuticals or fillers for, for example, polymers, paper, fibers, ceramics, coatings, paints or food additives.For example, the particulate composition of the present invention can be used as an IR-blocker in cosmetics. The invention will be further described with reference to the following drawings. It will be understood that the following description and references to these drawings relate to exemplary embodiments of the invention and should not be construed as limiting the scope of the claims. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a field emission gun scanning electron microscope (FEG-SEM) image showing synthetic talc (dark grey) containing 10,000 ppm Au (white spots). [Figure 2a] FIG. 1 is a transmission electron microscope (TEM) image showing the surface of synthetic talc (light) containing 10,000 ppm Au (black). [Figure 2b] The same TEM image as in Figure 2a is shown enlarged. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention according to the appended claims provides a method for producing a novel particulate composition comprising a particulate layered mineral in which precious metal nanoparticles are intimately bonded to the surface of layered mineral platelets. The exact type of bond between the precious metal and the layered mineral is unknown, but the relative arrangement of the layered mineral and the precious metal can only be observed by electron microscopy, as shown in Figure 1 (FEG-SEM) and Figures 2a and 2b (TEM). As used herein, FEG-SEM and TEM are used to determine sizes and dimensions according to methods known to those skilled in the art, for example as shown in WO 2015 / 159006 A1 and WO 2013 / 093376 A1. Without wishing to be bound by theory, it is believed that the noble metal nanoparticles preferably attach to the -(Si)OH and -(Mg)OH ends of the platelets. According to the present invention, the composition contains a greater proportion of layered minerals and a smaller proportion of precious metals. For example, the mass ratio of layered minerals to precious metals is 1:1-10. 6 :1. As used herein, the amount of precious metal in the composition according to the invention is expressed as parts per million (ppm), where ppm indicates the mass ratio of precious metal to layered mineral.

[0012] The versatility of the method of the present invention lies in the fact that, on the one hand, the layered mineral source is an aqueous solution comprising a layered mineral or a layered mineral precursor, such as a soluble metasilicate and / or metagermanate, optionally in combination with a carboxylate salt, and, on the other hand, that the precious metal source may be a precious metal or a precious metal salt. For example, the method can be carried out by combining a layered mineral, such as particulate talc, with a precious metal, such as gold nanoparticles. For example, the method can be carried out by combining a layered mineral precursor, such as an aqueous solution containing soluble metasilicate and / or metagermanate, optionally in combination with a carboxylate, with a precious metal, such as gold nanoparticles. For example, the method can be carried out by combining a layered mineral such as particulate talc with a precious metal precursor such as a soluble gold salt. For example, the method can be carried out by combining a layered mineral precursor, such as an aqueous solution containing soluble metasilicate and / or metagermanate, optionally in combination with a carboxylate, with a precious metal precursor, such as soluble gold nanoparticles. Moreover, versatility is further determined by the fact that the order of addition of the various components has little effect on the reaction and reaction products, as the exact nature of the final product obtained will vary little based on the order of addition of the components in the formation, since all combinations lead to the product of the invention being formed.

[0013] It should be noted that the present invention may include any combination of the features and / or limitations mentioned herein, except for combinations of such features that are mutually exclusive. The foregoing description relates to specific embodiments of the present invention to illustrate the present invention. However, it will be apparent to those skilled in the art that many modifications and variations to the embodiments described herein are possible. All such modifications and variations are intended to be within the scope of the present invention, as defined by the appended claims. EXAMPLES

[0014] Example 1 This example uses a synthetic aqueous talc dispersion as the layered mineral source and gold nanoparticles as the precious metal source. In a beaker, 6.3 mL of gold nanoparticle solution (0.05 mg / ml) was added to 32.6 g of synthetic talc aqueous dispersion (corresponding to 1.5 g of dry talc). The resulting mixture was diluted with 150 mL of distilled water, mixed and sonicated for a few minutes. Once well dispersed, the suspension was centrifuged at 9000 rpm for 1 h 30 min. Finally, the supernatant was completely clear and colorless, while the synthetic talc residue was reddish, indicating the presence of gold nanoparticles. The theoretical loading would be 0.315 mg gold per 1.5 g talc, corresponding to a loading of 210 ppm. When attempting to carry out experiments with theoretical loadings above 3000 ppm, the supernatant was colored red after centrifugation, indicating that not all gold nanoparticles were incorporated into the talc.

[0015] Example 2 This example uses hydrated sodium metasilicate and magnesium acetate as the source of layered minerals to form talc in situ, and chloroauric acid as the source of precious metals to form gold in situ. 42.4 g (0.2 mol) of sodium metasilicate pentahydrate was dissolved in 300 mL of distilled water in a first beaker (A) under magnetic stirring and ultrasonication. 103.5 g of anhydrous sodium acetate was added. In a second beaker (B), 32.17 g (0.15 mol) of magnesium acetate tetrahydrate was dissolved in 100 mL of acetic acid 1M under magnetic stirring and ultrasonication. 0.8 mL of 10 mg / mL HAuCl43 hydrate solution was added to beaker (B). The contents of beaker (B) were quickly added to the contents of beaker (A) with hand stirring to obtain a white suspension. The resulting aqueous suspension was treated in a hydrothermal reactor at 300 °C under autogenous pressure (85 bar) for 6 h. At the end of the hydrothermal treatment, a red gel was obtained, which was washed several times with distilled water. A red paste was obtained, which can be dried in a desiccator, oven (120 °C) or centrifuge to obtain a purple particulate solid. The theoretical loading would be 4 mg gold per 18.96 g talc, corresponding to a loading of approximately 210 ppm. The experiment was repeated with theoretical loadings of 100 ppm, 500 ppm, and 10,000 ppm, each time yielding a clear, colorless supernatant after centrifugation, indicating that all the gold nanoparticles formed in situ were bound to the talc formed in situ.

[0016] Example 3 This example uses a mixture of hydrated sodium metasilicate and magnesium acetate as the source of layered minerals to form talc in situ, and chloroauric acid and chloroplatinic acid as the source of precious metals to form gold and platinum in situ. 42.4 g (0.2 mol) of sodium metasilicate pentahydrate was dissolved in 300 mL of distilled water in a first beaker (A) under magnetic stirring and ultrasonication. 103.5 g of anhydrous sodium acetate was added. In a second beaker (B), 32.17 g (0.15 mol) of magnesium acetate tetrahydrate was dissolved in 100 mL of acetic acid 1M under magnetic stirring and ultrasonication. 1.90 mL of a 10 mg / mL HAuCl43 hydrate solution and 2.45 mL of a 10.25 mg / mL HPtCl66 hydrate solution were added to beaker (B). The contents of beaker (B) were quickly added to the contents of beaker (A) with manual stirring to obtain a white suspension. The resulting aqueous suspension was treated in a hydrothermal reactor at 300 °C under autogenous pressure (85 bar) for 6 h. At the end of the hydrothermal treatment, a grey gel was obtained, which was washed several times with distilled water. The theoretical loading would be 9.48 mg gold and 9.48 mg platinum per 18.96 g talc, corresponding to a loading of approximately 500 ppm gold and platinum, respectively.

[0017] Example 4 This example uses hydrated sodium metasilicate and magnesium acetate as the source of layered minerals to form talc in situ, and a mixture of chloroplatinic acid, sodium tetrachloropalladate(II) and ammonium hexachlororhodate(III) as the source of precious metals to form platinum, palladium and rhodium in situ. 42.4 g (0.2 mol) of sodium metasilicate pentahydrate was dissolved in 300 mL of distilled water in a first beaker (A) under magnetic stirring and ultrasonication. 103.5 g of anhydrous sodium acetate was added. In a second beaker (B), 32.17 g (0.15 mol) of magnesium acetate tetrahydrate was dissolved in 100 mL of acetic acid 1M under magnetic stirring and ultrasonication. 4.90 mL of 10.25 mg / mL H2PtCl66 hydrate solution, 5.23 mL of 10 mg / mL Cl4Na2Pd solution and 6.55 mL of 10.39 mg / mL RhCl6(NH4)3 solution were added to beaker (B). The contents of beaker (B) were added quickly to the contents of beaker (A) with manual stirring to obtain a white suspension. The resulting aqueous suspension was treated in a hydrothermal reactor at 300 °C under autogenous pressure (85 bar) for 6 h. At the end of the hydrothermal treatment, a dark gel was obtained, which was washed several times with distilled water. The theoretical loading would be 18.96 mg platinum, 18.96 mg palladium and 18.96 mg rhodium per 18.96 mg talc, corresponding to a loading of about 1000 ppm for each of platinum, palladium and rhodium.

[0018] Example 5 This example uses hydrated sodium metasilicate and magnesium acetate as the source of layered minerals that form talc in situ, and gold nanoparticles as the source of precious metals. 42.4 g (0.2 mol) of sodium metasilicate pentahydrate was dissolved in 300 mL of distilled water in a first beaker (A) under magnetic stirring and sonication. 103.5 g of anhydrous sodium acetate was added. In a second beaker (B), 32.17 g (0.15 mol) of magnesium acetate tetrahydrate was dissolved in 100 mL of acetic acid 1M under magnetic stirring and sonication. 80 mL of gold nanoparticle solution (0.05 mg / mL) was added to beaker (B). During this mixture, the red solution of gold nanoparticles instantly turns into a deep blue / dark solution. The contents of beaker (B) were quickly added to the contents of beaker (A) with manual stirring to obtain a white suspension. The resulting aqueous suspension was treated in a hydrothermal reactor at 300 °C under autogenous pressure for 6 h. At the end of the hydrothermal treatment, a red gel was obtained, which was washed several times with distilled water and then centrifuged to obtain a blue-purple product and a clear, colorless supernatant. The theoretical loading would be 4 mg gold per 18.96 g talc, corresponding to a loading of approximately 210 ppm.

[0019] Example 6 This example uses a synthetic aqueous talc dispersion as the layered mineral source and chloroauric acid as the precious metal source to form gold in situ. In a beaker, 43.48 g of synthetic talc aqueous dispersion (corresponding to 2 g of dry talc) was added to 84 μL of HAuCl43 hydrate solution (10 mg / mL). Distilled water was added up to 150 mL. The suspension was then mixed under magnetic stirring and ultrasonication. Once well dispersed, the mixture was placed in an autoclave at 300 °C and 86 bar for 1 h. At the end of the hydrothermal treatment, a red paste was obtained and the product was collected by centrifugation. The theoretical loading would be 4 mg gold per 18.96 g talc, corresponding to a loading of approximately 210 ppm.

[0020] Example 7 This example uses natural talc as the layered mineral source and chloroauric acid as the precious metal source to form gold in situ. In a beaker, 2 g of dry natural talc (white powder) was added to 4 mL of HAuCl43 hydrate solution (10 mg / mL). Distilled water was added up to 20 mL. The suspension was mixed under magnetic stirring and ultrasonication. The mixture was then placed in an autoclave at 300 °C and 86 bar for 6 h. At the end of the hydrothermal treatment, a red suspension was obtained and the product was dried in an oven at 120 °C. The theoretical loading would be 20 mg gold per 2 g talc, corresponding to a loading of approximately 10,000 ppm.

[0021] Example 8: This example uses natural talc as the layered mineral source and chloroauric acid as the precious metal source to form gold in situ. The preparation is the same as in Example 2. The aqueous suspension obtained after mixing the layered mineral source and the gold source is not hydrothermally treated but is kept at room temperature. The suspension turns reddish immediately the next day and becomes more and more reddish with time, indicating that there is a reduction of gold and synthesis of gold particles.

Claims

1. A method for preparing a mixture containing a precious metal and a layered mineral, comprising the steps of: (a) providing a layered mineral source; (b) providing a source of a precious metal; and (c) combining the layered mineral source of step (a) with the precious metal source of step (b). It consists of: The method, wherein the layered mineral of the layered mineral source is talc, the surface of the layered mineral source is not modified or functionalized, and the precious metal of the precious metal source is selected from the group consisting of gold, palladium, platinum, iridium, ruthenium, rhodium, or mixtures thereof.

2. 2. The method of claim 1, wherein the layered mineral source in step (a) is a combination of (i) an aqueous solution containing a soluble metasilicate and / or a soluble metagermanate, optionally in combination with a carboxylate salt, and (ii) an aqueous solution containing a soluble metal salt.

3. 3. The method of claim 1 or 2, wherein the source of precious metal is an aqueous solution comprising a soluble precious metal salt.

4. 3. The method of claim 2, wherein the soluble metasilicate and / or the soluble metagermanate in step (a) are selected from the respective sodium or potassium salts, or mixtures thereof, and / or the optional carboxylate in step (a) is a metal carboxylate, the metal being selected from sodium or potassium, or mixtures thereof.

5. 3. The method of claim 2, wherein the optional carboxylate in step (a) is selected from formate, acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, or mixtures thereof.

6. 3. The method of claim 2, wherein the metal of the soluble metal salt in step (a) is a divalent metal selected from magnesium, cobalt, zinc, copper, manganese, iron, nickel, chromium or mixtures thereof.

7. The method of claim 6, wherein the soluble metal salt is magnesium acetate.

8. 4. The method of claim 3, wherein the precious metal of the soluble precious metal salt in step (b) is selected from gold, palladium, platinum, iridium, ruthenium, rhodium, or mixtures thereof.

9. 3. The method of claim 2, wherein the combining step (c) is carried out by mixing the precious metal source of step (b) with component (i) of the layered mineral source of step (a) and component (ii) of the layered mineral source of step (a) in any order.

10. 10. The process according to any one of claims 1 to 9, comprising a step (d) of hydrothermally treating the mixture obtained at the end of step (c), said hydrothermal treatment being carried out by heating at a temperature between 100°C and 600°C for a duration ranging from 10 minutes to 30 days, said heating being achieved by microwave heating, convection heating or a combination thereof.

11. 11. The process according to any one of claims 1 to 10, comprising a step (d) of hydrothermally treating the mixture obtained at the end of step (c), wherein the product obtained after step (c) of combining or after step (d) of hydrothermally treating is dried, washed and / or centrifuged.

12. 12. The process according to any one of claims 1 to 11, comprising a step (d) of hydrothermally treating the mixture obtained at the end of step (c), said hydrothermal treatment being carried out as a batch process in an autoclave under autogenous pressure.

13. 12. The process according to any one of claims 1 to 11, comprising a step (d) of hydrothermally treating the mixture obtained at the end of step (c), said hydrothermal treatment being carried out as a continuous process under a pressure of at least 1 MPa.

14. A particulate composition comprising a combination of layered mineral and precious metal obtained by the method of any one of claims 1 to 13, The particulate composition wherein the layered mineral is talc and the precious metal is selected from the group consisting of gold, palladium, platinum, iridium, ruthenium, rhodium, or mixtures thereof.

15. 15. The particulate composition of claim 14, wherein the precious metal is in the form of nanoparticles bound to the surface of a layered mineral.

16. 16. A particulate composition according to claim 15, wherein said precious metal nanoparticles have an average particle size in the range of 1 nm to 100 nm and / or said layered mineral particles are platelets having a major diameter in the range of 10 nm to 1 mm.

17. Use of a particulate composition according to any one of claims 14 to 16 or a method according to any one of claims 1 to 13 in the manufacture of a catalyst, a cosmetic, a pharmaceutical or a filler.

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