WO2005105673A1 - Metal mixed oxide powder containing noble metal - Google Patents

Metal mixed oxide powder containing noble metal Download PDF

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Publication number
WO2005105673A1
WO2005105673A1 PCT/EP2005/004125 EP2005004125W WO2005105673A1 WO 2005105673 A1 WO2005105673 A1 WO 2005105673A1 EP 2005004125 W EP2005004125 W EP 2005004125W WO 2005105673 A1 WO2005105673 A1 WO 2005105673A1
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Prior art keywords
noble metal
mixed oxide
oxide powder
metal
powder according
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PCT/EP2005/004125
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French (fr)
Inventor
Stipan Katusic
Frank-Martin Petrat
Michael Krämer
Guido Zimmermann
Willlibald Wombacher
Edwin Staab
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Evonik Operations GmbH
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Degussa GmbH
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G1/00—Methods of preparing compounds of metals not covered by subclasses C01B, C01C, C01D, or C01F, in general
    • C01G1/02—Oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/62—Platinum group metals with gallium, indium, thallium, germanium, tin or lead
    • B01J23/622—Platinum group metals with gallium, indium, thallium, germanium, tin or lead with germanium, tin or lead
    • B01J23/626—Platinum group metals with gallium, indium, thallium, germanium, tin or lead with germanium, tin or lead with tin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/66—Silver or gold
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0238—Impregnation, coating or precipitation via the gaseous phase-sublimation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B01J37/082—Decomposition and pyrolysis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/16—Reducing
    • B01J37/18—Reducing with gases containing free hydrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G19/00—Compounds of tin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
    • B01J2235/15—X-ray diffraction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/613—10-100 m2/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/615—100-500 m2/g
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area

Definitions

  • the invention concerns a metal mixed oxide powder doped with a noble metal, its production and use.
  • Multi-metallic powders are known from US 5984997.
  • the multi-metallic powders comprise at least two elements selected from the s, p, d and/or f group of the periodic table.
  • the powders can be in aggregated or agglomerated form and display an average particle size of less than 5 ⁇ m.
  • the elements also include catalytically active noble metals, such as gold, platinum or palladium. They are produced by burning an emulsion containing the precursor elements of the selected compound and a flammable liquid.
  • the large number of possibilities means that many substance parameters can be adjusted in this way.
  • US 594997 does not disclose the form of the components in the powder, nor does it disclose the measures to be taken to influence the distribution of the components in the powder.
  • the particles display catalytically active centres in accessible sites.
  • the catalytically active element In flame processes, which generally lead to particles with no significant pore structure, the catalytically active element must preferably sit on the surface of the particles.
  • Catalysts are generally obtained by applying a catalytically active layer from a solution with subsequent calcination.
  • the disadvantage of catalysts produced in this way is often the inadequate adhesion of the catalytic layer that is applied.
  • the object of the invention is to provide a noble metal- containing catalyst that displays as high as possible a number of accessible active noble metal centres, which are permanently bonded to a support, which can likewise be catalytically active.
  • the invention provides an aggregated, doped metal mixed oxide powder, which is characterised in that - the BET surface area is 30 to 150 m 2 /g, - the doping component is at least one noble metal, - wherein the content of noble metal is 0.1 to 20 wt.%, ' relative to the total amount of powder, and - wherein the ratio of noble metal on the surface to the total amount of noble metal is at least 0.1.
  • the ratio of the amount of noble metal on the surface of the aggregates to the total amount of noble metal can preferably be 0.1 to 0.3.
  • the ratio can be determined, for example, by combined analysis of high-resolution TEM images that are representative of the sample, XPS/ESCA to determine the noble metal surface coverage and X-ray fluorescence analysis to determine the total content of noble metal .
  • the content of noble metal covers a wide range from 0.1 to 20 wt.%. This means that the content of catalytically active noble metal can be specially adjusted to a particular subsequent use. The content is conventionally between 5 and 15 wt.%.
  • the noble metal on the surface of the powder according to the invention can display an average diameter of 2 to 10 nm. Particularly good catalytic activity can be expected with diameters of this order of magnitude.
  • the powder according to the invention can preferably contain Pt, Pd, Rh, Ru, Au or Ag as noble metal. Platinum or gold are particularly preferred.
  • the powder according to the invention can preferably have a BET surface area of 30 to 150 m 2 /g and particularly preferably a BET surface area of 50 to 70 m 2 /g.
  • the BET surface area is an important feature of catalytic activity and in the powder according to the invention it can be adjusted to the intended catalytic reaction.
  • the metal mixed oxide powders within the meaning of the invention are ones which can be produced by oxidation from inorganic or organic precursors.
  • the metal mixed oxide powders can preferably display the elements Na, K, Mg, Ca, Y, Ce, Ti, Zr, V, Nb, Mo, W, Mn, Fe, Co, Ni, Ag, Zn, Al, In, Si, Sn, Sb or Bi .
  • Within an aggregate the metal oxides can be positioned alongside one another or can be in the form of true metal mixed oxides . Aggregates are understood to be three-dimensional structures of intergrown primary particles. Primary particles are the particles first formed in a flame during the oxidation reaction.
  • the metal mixed oxide powders can preferably be binary oxides, in other words oxides displaying two metals. Of these, indium-tin oxide is particularly preferred.
  • the content in wt.% of indium oxide, calculated as ln 2 0 3 , can preferably be 70 to 95, that of tin oxide, calculated as Sn0 2 , 1 to 10 wt.%, relative in each case to the powder according to the invention.
  • a powder having indium-tin oxide as the metal oxide component can preferably display platinum or gold as the noble metal component.
  • the invention also provides a process for the production of the powder according to the invention wherein a solution or dispersion containing compounds with the metal components of the oxides is atomised according to the subsequently desired ratio of oxides, in a first zone of a reactor, optionally with admixture of an inert gas stream, the atomised solution is pyrolysed in a flame consisting of hydrogen and air or oxygen-enriched air, in an area comprising the last third of the flame, the noble metal component in the form of a solution or dispersion of a noble metal compound is metered into the pyrolysis mixture at one or more points, in an amount corresponding to the subsequently desired amount of noble metal and immediately afterwards reducing gases are added in a second zone, the reducing gases being added in an amount such that a reducing atmosphere is established overall in this second zone, thereafter in a third zone
  • the liquid phase of the solution or dispersion can contain water, organic solvents or mixtures thereof. Water is preferably used, in order to prevent organic constituents in the powder .
  • Suitable starting substances for the metal mixed oxides can be inorganic or organic compounds, which can be converted into the oxides under the reaction conditions. As with the solvents, inorganic compounds are preferred here too for the same reasons .
  • halogens can advantageously be used, chlorides being particularly advantageous .
  • noble metal compounds There is a limit on the number of noble metal compounds. Here too it is in principle the case that purely inorganic compounds can preferably be used. Nevertheless, good results can also be obtained with organic noble metal compounds .
  • the following compounds that can be used are cited by way of example: PtCl 2 , PtCl , H [PtCl 5 ], PdCl 2 , Pd acetate, Pd(N0 3 ) 2 , RhCl 3 , Rh(N0 3 ) 3 , RuCl 3 , IrCl 3 , H[AuCl 4 ], AgN0 3 .
  • Forming gas, carbon monoxide, hydrogen, ammonia or mixtures of these gases can be used as reducing gases .
  • the use of reducing gases is substantially in order to obtain powders having high catalytic activity.
  • the residence time is between 0.8 and 1.5 seconds in the first zone and is between 15 seconds and 15 minutes in total in the second and third zone.
  • Figure 1 shows a schematic set-up for performing the process according to the invention.
  • I, II and III indicate the three reaction zones.
  • Zone la describes the ' area in which the noble metal component is added.
  • 1 atomised solution or dispersion of the metal compounds
  • 2 oxygen-containing gas, preferably air
  • 3 combustion gas, preferably hydrogen
  • 4 solution or dispersion containing noble metal compound
  • 5 reducing gas
  • 6 waste gas
  • 7 powder according to the invention.
  • the solution or dispersion of the noble metal compound be fed into zone la.
  • Example 1 An aqueous solution containing 88.9 g/1 of indium(III) chloride and 8.4 g/1 of tin(IV) chloride is atomised by means of compressed air and a nozzle (diameter 0.8 mm) into the reaction tube at a delivery rate of 1500 ml/h.
  • An oxyhydrogen flame consisting of 5 m 3 /h of hydrogen and 15 m 3 /h of air is burning there.
  • a one- percent, aqueous H [PtCl 6 ] solution is fed into the last third of this flame.
  • Forming gas (5 Nm 3 /h) is introduced immediately after the addition of the solution.
  • the reaction mixture passes through a residence time section of 2 m in length in 14 seconds.
  • the solid is then separated from the gaseous substances using a filter and treated for a period of 15 minutes at a temperature of 250°C with a continuous supply of forming gas.
  • Examples 2 to 4 are performed in the same way as Example 1.
  • the feed materials and amounts used are reproduced in Table 1, the analytical data for the powders in Table 2.
  • Figure 2 shows the X-ray diffraction diagram for the powder according to the invention from Example 3.
  • Table 1 Feed materials and amounts used
  • NM noble metal

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Abstract

Aggregated, doped metal mixed oxide powder having a BET surface area of 30 to 150 m²/g, wherein the doping component is at least one noble metal and the content of noble metal is 0.1 to 20 wt.% and wherein the ratio of noble metal on the surface to the total amount of noble metal is at least 0.1. It is produced by pyrolysing compounds containing the metal component of the mixed metal oxide in a first zone in a flame consisting of hydrogen and air and metering a noble metal compound and reducing gas into the pyrolysis mixture in a second zone and separating off the solid obtained in a third zone. The mixed oxide powder doped with noble metal can be used as a catalyst.

Description

Metal mixed oxide powder containing noble metal
The invention concerns a metal mixed oxide powder doped with a noble metal, its production and use.
Multi-metallic powders are known from US 5984997. The multi-metallic powders comprise at least two elements selected from the s, p, d and/or f group of the periodic table. The powders can be in aggregated or agglomerated form and display an average particle size of less than 5 μm. The elements also include catalytically active noble metals, such as gold, platinum or palladium. They are produced by burning an emulsion containing the precursor elements of the selected compound and a flammable liquid. There are many possibilities here, such as e.g. combustion in a laminar or turbulent flame, a diffusion flame, an additionally doped or undoped flame. The large number of possibilities means that many substance parameters can be adjusted in this way.
However, US 594997 does not disclose the form of the components in the powder, nor does it disclose the measures to be taken to influence the distribution of the components in the powder.
For use as a catalyst in particular, however, it is extremely important that the particles display catalytically active centres in accessible sites. In flame processes, which generally lead to particles with no significant pore structure, the catalytically active element must preferably sit on the surface of the particles.
Catalysts are generally obtained by applying a catalytically active layer from a solution with subsequent calcination. The disadvantage of catalysts produced in this way is often the inadequate adhesion of the catalytic layer that is applied.
The object of the invention is to provide a noble metal- containing catalyst that displays as high as possible a number of accessible active noble metal centres, which are permanently bonded to a support, which can likewise be catalytically active.
The invention provides an aggregated, doped metal mixed oxide powder, which is characterised in that - the BET surface area is 30 to 150 m2/g, - the doping component is at least one noble metal, - wherein the content of noble metal is 0.1 to 20 wt.%,' relative to the total amount of powder, and - wherein the ratio of noble metal on the surface to the total amount of noble metal is at least 0.1.
The ratio of the amount of noble metal on the surface of the aggregates to the total amount of noble metal can preferably be 0.1 to 0.3. The ratio can be determined, for example, by combined analysis of high-resolution TEM images that are representative of the sample, XPS/ESCA to determine the noble metal surface coverage and X-ray fluorescence analysis to determine the total content of noble metal .
The content of noble metal covers a wide range from 0.1 to 20 wt.%. This means that the content of catalytically active noble metal can be specially adjusted to a particular subsequent use. The content is conventionally between 5 and 15 wt.%.
The noble metal on the surface of the powder according to the invention can display an average diameter of 2 to 10 nm. Particularly good catalytic activity can be expected with diameters of this order of magnitude. The powder according to the invention can preferably contain Pt, Pd, Rh, Ru, Au or Ag as noble metal. Platinum or gold are particularly preferred.
The powder according to the invention can preferably have a BET surface area of 30 to 150 m2/g and particularly preferably a BET surface area of 50 to 70 m2/g. The BET surface area is an important feature of catalytic activity and in the powder according to the invention it can be adjusted to the intended catalytic reaction. The metal mixed oxide powders within the meaning of the invention are ones which can be produced by oxidation from inorganic or organic precursors. The metal mixed oxide powders can preferably display the elements Na, K, Mg, Ca, Y, Ce, Ti, Zr, V, Nb, Mo, W, Mn, Fe, Co, Ni, Ag, Zn, Al, In, Si, Sn, Sb or Bi . Within an aggregate the metal oxides can be positioned alongside one another or can be in the form of true metal mixed oxides . Aggregates are understood to be three-dimensional structures of intergrown primary particles. Primary particles are the particles first formed in a flame during the oxidation reaction.
The metal mixed oxide powders can preferably be binary oxides, in other words oxides displaying two metals. Of these, indium-tin oxide is particularly preferred.
The content in wt.% of indium oxide, calculated as ln203, can preferably be 70 to 95, that of tin oxide, calculated as Sn02, 1 to 10 wt.%, relative in each case to the powder according to the invention.
A powder having indium-tin oxide as the metal oxide component can preferably display platinum or gold as the noble metal component.
Such a powder whose X-ray diffraction diagram shows the diffraction pattern of cubic indium oxide and an indium- platinum alloy or indium-gold alloy is particularly preferred. The invention also provides a process for the production of the powder according to the invention wherein a solution or dispersion containing compounds with the metal components of the oxides is atomised according to the subsequently desired ratio of oxides, in a first zone of a reactor, optionally with admixture of an inert gas stream, the atomised solution is pyrolysed in a flame consisting of hydrogen and air or oxygen-enriched air, in an area comprising the last third of the flame, the noble metal component in the form of a solution or dispersion of a noble metal compound is metered into the pyrolysis mixture at one or more points, in an amount corresponding to the subsequently desired amount of noble metal and immediately afterwards reducing gases are added in a second zone, the reducing gases being added in an amount such that a reducing atmosphere is established overall in this second zone, thereafter in a third zone, in which a reducing atmosphere likewise prevails, the solid obtained is separated off.
The use of solutions is preferred within the meaning of the invention. Although dispersions can also be used, it has been found that the process allows the reaction to be controlled more easily if solutions are used.
The liquid phase of the solution or dispersion can contain water, organic solvents or mixtures thereof. Water is preferably used, in order to prevent organic constituents in the powder .
Suitable starting substances for the metal mixed oxides can be inorganic or organic compounds, which can be converted into the oxides under the reaction conditions. As with the solvents, inorganic compounds are preferred here too for the same reasons .
With regard to the properties of the powders according to the invention and for cost reasons, halogens can advantageously be used, chlorides being particularly advantageous .
There is a limit on the number of noble metal compounds. Here too it is in principle the case that purely inorganic compounds can preferably be used. Nevertheless, good results can also be obtained with organic noble metal compounds . The following compounds that can be used are cited by way of example: PtCl2, PtCl , H [PtCl5], PdCl2, Pd acetate, Pd(N03)2, RhCl3, Rh(N03)3, RuCl3, IrCl3, H[AuCl4], AgN03. Forming gas, carbon monoxide, hydrogen, ammonia or mixtures of these gases can be used as reducing gases . The use of reducing gases is substantially in order to obtain powders having high catalytic activity.
It has proved to be advantageous if the residence time is between 0.8 and 1.5 seconds in the first zone and is between 15 seconds and 15 minutes in total in the second and third zone.
Figure 1 shows a schematic set-up for performing the process according to the invention. I, II and III indicate the three reaction zones. Zone la describes the' area in which the noble metal component is added. In addition: 1 = atomised solution or dispersion of the metal compounds; 2 = oxygen-containing gas, preferably air; 3 = combustion gas, preferably hydrogen; 4 = solution or dispersion containing noble metal compound; 5 = reducing gas; 6 = waste gas; 7 = powder according to the invention.
In order to be able to obtain the powder according to the invention, it is essential that the solution or dispersion of the noble metal compound be fed into zone la. This leads to powders according to the invention wherein the noble metal component is permanently bonded to the mixed metal oxide. This can be verified by means of X- ray diffraction diagrams and XPS spectra (presence of indium-platinum bonds in XRD or strong interactions with the mixed metal oxide matrix in the XPS spectra) .
It is also essential to provide a reducing atmosphere immediately after adding the noble metal compound, in order to prevent as far as possible an undesirable oxidation of the noble metal.
Examples :
Example 1 : An aqueous solution containing 88.9 g/1 of indium(III) chloride and 8.4 g/1 of tin(IV) chloride is atomised by means of compressed air and a nozzle (diameter 0.8 mm) into the reaction tube at a delivery rate of 1500 ml/h. An oxyhydrogen flame consisting of 5 m3/h of hydrogen and 15 m3/h of air is burning there. A one- percent, aqueous H [PtCl6] solution is fed into the last third of this flame. Forming gas (5 Nm3/h) is introduced immediately after the addition of the solution.
The reaction mixture passes through a residence time section of 2 m in length in 14 seconds. The solid is then separated from the gaseous substances using a filter and treated for a period of 15 minutes at a temperature of 250°C with a continuous supply of forming gas.
Examples 2 to 4 are performed in the same way as Example 1. The feed materials and amounts used are reproduced in Table 1, the analytical data for the powders in Table 2. Figure 2 shows the X-ray diffraction diagram for the powder according to the invention from Example 3. Table 1 : Feed materials and amounts used
Figure imgf000008_0001
a) Tin tetrachloride pentahydrate
Table 2 : Analytical data for the powders according to the invention
Figure imgf000008_0002
NM = noble metal; § in accordance with DIN 66131;

Claims

Claims :
1. Aggregated, doped metal mixed oxide powder, characterised in that - the BET surface area is 30 to 150 m2/g, - the doping component is at least one noble metal, - wherein the content of noble metal is 0.1 to 20 wt.%, relative to the total amount of powder, and - wherein the ratio of noble metal on the surface to the total amount of noble metal is at least 0.1.
2. Aggregated, doped metal mixed oxide powder according to claim 1, characterised in that the ratio of the amount of noble metal on the surface of the aggregates to the total amount of noble metal is 0.1 to 0.3.
3. Aggregated, doped metal mixed oxide powder according to claims 1 or 2, characterised in that the noble metal on the surface has an average diameter of 2 to 10 nm.
4. Aggregated, doped metal mixed oxide powder according to claims 1 to 3 , characterised in that the BET surface area is 30 to 150 m2/g. 5. Aggregated, doped metal mixed oxide powder according to claims 1 to 4, characterised in that the noble metal is Pt, Pd, Rh, Ru, Au or Ag.
6. Aggregated, doped metal mixed oxide powder according to claims 1 to 5, characterised in that the metal mixed oxide powder displays the elements Na, K, Mg, Ca, Y, Ce, Ti, Zr, V, Nb, Mo, W, Mn, Fe, Co, Ni, Ag, Zn, Al, In, Si, Sn, Sb or Bi .
7. Aggregated, doped metal mixed oxide powder according to claims 1 to 6, characterised in that the metal mixed oxide powder is a binary oxide.
8. Aggregated, doped metal mixed oxide powder according to claim 7, characterised in that the binary oxide is indium-tin oxide.
9. Aggregated, doped metal mixed oxide powder according to claim 8, characterised in that the content, in wt.%, of indium oxide, calculated as ln03, is 70 to 95, that of tin oxide, calculated as Sn02, is 1 to 10. 10. ggregated, doped metal mixed oxide powder according to claims 1 to 9 , characterised in that it displays platinum or gold.
11. Aggregated, doped indium-tin mixed oxide powder according to claims 8 to 10, characterised in that an X- ray diffraction diagram shows the diffraction pattern of cubic indium oxide and an indium-platinum alloy or indium-gold alloy.
12. Process for the production of the powder according to claims 1 to 11, characterised in that - a solution or dispersion, containing compounds with the metal components of the oxides, is atomised according to the subsequently desired ratio of oxides, in a first zone of a reactor, optionally with admixture of an inert gas stream, the atomised solution is pyrolysed in a flame consisting of hydrogen and air or oxygen-enriched air, in an area comprising the last third of the flame, the noble metal component in the form of a solution or dispersion of a noble metal compound is metered into the pyrolysis mixture at one or more points, in an amount corresponding to the subsequently desired amount of noble metal and immediately afterwards reducing gases are added in a second zone, the reducing gases being added in an amount such that a reducing atmosphere is established overall in this second zone, thereafter in a third zone, in which a reducing atmosphere likewise prevails, the solid obtained is separated off.
3. Use of the powder according to claims 1 to 11 as a catalyst.
PCT/EP2005/004125 2004-05-05 2005-04-19 Metal mixed oxide powder containing noble metal Ceased WO2005105673A1 (en)

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EP2399869A1 (en) * 2010-06-25 2011-12-28 Evonik Degussa GmbH Mixed oxide powder containing the elements lithium, manganese, nickel and cobalt and method for producing same
EP2506350B1 (en) * 2009-11-27 2017-03-29 University of Yamanashi Oxide-based stable high-potential carrier for solid polymer fuel cell

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EP2506350B1 (en) * 2009-11-27 2017-03-29 University of Yamanashi Oxide-based stable high-potential carrier for solid polymer fuel cell
EP2399867A1 (en) * 2010-06-25 2011-12-28 Evonik Degussa GmbH Method for producing mixed oxides containing lithium
EP2399869A1 (en) * 2010-06-25 2011-12-28 Evonik Degussa GmbH Mixed oxide powder containing the elements lithium, manganese, nickel and cobalt and method for producing same
WO2011160940A1 (en) * 2010-06-25 2011-12-29 Evonik Degussa Gmbh Method for producing mixed oxides comprising lithium
WO2011160907A1 (en) * 2010-06-25 2011-12-29 Evonik Degussa Gmbh Mixed oxide powder containing the elements lithium, manganese, nickel and cobalt and method for producing same
CN102906023A (en) * 2010-06-25 2013-01-30 赢创德固赛有限公司 Method for producing mixed oxides comprising lithium
CN102958845A (en) * 2010-06-25 2013-03-06 赢创德固赛有限公司 Mixed oxide powder containing the elements lithium, manganese, nickel and cobalt and method for producing same
CN102958845B (en) * 2010-06-25 2015-01-07 赢创德固赛有限公司 Mixed oxide powder containing the elements lithium, manganese, nickel and cobalt and method for producing same
CN102906023B (en) * 2010-06-25 2015-04-01 赢创德固赛有限公司 Method for producing mixed oxides comprising lithium

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