Process for the production of metal oxide powders

1. Process for the production of a metal oxide powder having a BET surface area of at least 20 m 2 /g comprising reacting an aerosol with oxygen in a reaction space at a reaction temperature of more than 700° C. and then separating the resulting powder from gaseous substances in the reaction space, wherein

the aerosol is obtained by atomising using a three-component nozzle or four-component nozzle at least one starting material, either as such in liquid form or in solution, and at least one atomising gas,

the volume-related mean drop diameter D 30 of the aerosol is from 30 to 100 μm,

the number of aerosol drops larger than 100 μm is up to 10%, based on the total number of drops, and

two or three separate solutions which contain the same or different starting materials, in the same or different solvents, in the same or different concentrations are atomised with the three-component nozzle or four-component nozzle, in addition to the atomising gas.

2. Process according to claim 1 , wherein the number of aerosol drops, based on the total number of drops, larger than 100 μm is from 3% to 8%.

3. Process according to claim 1 , wherein the percentage of aerosol drops larger than 250 μm is not more than 10%, based on the number of drops >100 μm.

4. Process according to claim 1 , wherein the following applies for the volume-related mean drop diameter D 30 [μm] in dependence on the spray width [mm] of the aerosol:

Spray width

D 30

0

10 to 30

±20

20 to 40

±40

30 to 60

±60

50 to 80

±80

80 to 120.

5. Process according to claim 1 , wherein the at least one starting material is in solution and the throughput of the solution is from 1.5 to 2000 kg/h.

6. Process according to claim 1 , wherein the at least one starting material is in solution and has a metal content in the solution of from 2 to 40 wt. %.

7. Process according claim 1 , wherein the at least one starting material comprises as the metal component at least one metal selected from the group consisting of Al, Ce, Fe, Mg, In, Ti, Si, Sn, Y, Zn and Zr.

8. Process according to claim 1 , wherein the at least one starting material comprises an organometallic compound.

9. Process according to claim 1 , wherein the at least one starting material is dissolved in an organic solvent to form said solution.

10. Process according to claim 9 , wherein the organic solvent is at least one carboxylic acid having from 2 to 12 carbon atoms.

11. Process according to claim 10 , wherein the content of said at least one carboxylic acid is less than 60 wt. %.

12. Process according to claim 1 , wherein the atomising gas is air.

13. Process according to claim 1 , wherein the starting material is in solution, and the ratio throughput of the solution/amount of atomising gas is from 2 to 25 kg/Nm 3 .

14. Process according to claim 1 , wherein the reaction temperature is obtained by a flame produced by reaction of a hydrogen-containing combustion gas with oxygen and/or air.

15. Process according to claim 14 , wherein secondary air is additionally introduced into the reaction space.

16. Process according to claim 14 , wherein lambda is ≧1.5, lambda being calculated from the quotient of the sum of the oxygen content of the air and, optionally, of the atomising gas and the sum of the starting materials and the hydrogen-containing combustion gas, in each case in mol/h.

17. Process according claim I, wherein the metal oxide powder comprises Ce oxide exhibiting an isoelectric point at pH values from 9 to 11.