Process for producing titanium dioxide
View Patent ↗This disclosure relates to a process for producing titanium dioxide, comprising: a) providing a quantity of liquid titanium tetrahalide for reacting with an oxygen-containing gas; b) vaporizing a first portion of the liquid titanium tetrahalide and reacting the titanium tetrahalide vapor and the oxygen-containing gas, in a first stage of a reaction zone, the reaction zone temperature ranging from at least about 650° C.—to form a reaction product at least containing titanium dioxide and oxygen-containing gas and passing the reaction product, more typically in the vapor phase, to at least one additional stage of the reaction zone; and c) charging at least one additional portion of the liquid titanium tetrahalide to the at least one additional stage of the reaction zone to cool the titanium dioxide and to react with the oxygen-containing gas to form additional titanium dioxide. This process results in a high conversion to titanium dioxide and formation of titanium dioxide powders having improved particle size and size distribution.
1. A process for producing titanium dioxide, comprising:
a) providing a quantity of liquid titanium tetrahalide for reacting with an oxygen-containing gas;
b) vaporizing a first portion of the liquid titanium tetrahalide and reacting the titanium tetrahalide vapor and the oxygen-containing gas, in a first stage of a reaction zone, the reaction zone temperature being sufficient to form a reaction product at least containing titanium dioxide and oxygen-containing gas and passing the reaction product to at least one additional stage of the reaction zone; and
c) charging at least one additional portion of the liquid titanium tetrahalide directly into the at least one additional stage of the reaction zone at a temperature below the boiling point of the titanium tetrahalide, at the charge pressure of the titanium tetrahalide, to cool the titanium dioxide and to react with the oxygen-containing gas to form additional titanium dioxide, under conditions sufficient to form a product substantially free of titanium tetrahalide.
2. The process of claim 1 wherein the titanium dioxide is a pigment.
3. The process of claim 1 wherein about 1 to about 5 additional portions of the liquid titanium tetrahalide are charged to the additional stage.
4. The process of claim 3 wherein one additional portion of the liquid titanium tetrahalide is charged to the additional stage.
5. The process of claim 1 wherein the at least one additional portion of the liquid titanium tetrahalide is atomized.
6. The process of claim 5 wherein the atomization is accomplished with nitrogen, argon, carbon dioxide, or chlorine.
7. The process of claim 5 wherein the atomization is accomplished using an atomizing nozzle.
8. The process of claim 1 wherein the additional portion of the liquid titanium tetrahalide ranges from about 5 to about 90%, of the total quantity of the titanium tetrahalide provided.
9. The process of claim 8 wherein the additional portion of the liquid titanium tetrahalide is about 20 to about 70% of the total quantity of the titanium tetrahalide provided.
10. The process of claim 1 wherein the titanium tetrahalide is titanium tetrachloride.
11. The process of claim 10 wherein the first portion of the liquid titanium tetrahalide further comprises a rutile forming agent
12. The process of claim 11 wherein the rutile forming agent is aluminum halide.
13. The process of claim 12 wherein the aluminum halide is aluminum chloride.
14. The process of claim 10 wherein the liquid titanium tetrachloride is charged to the additional stage of the reaction zone at a temperature below the vapor pressure of the titanium tetrachloride determined by the equation:
Vapor Pressure of TiCl4=10(6.694−(1287.91/(T+201.2)))
wherein, Vapor Pressure is calculated in nit Hg, and T is the temperature of liquid titanium tetrachloride in degrees Celsius.
15. The process of claim 1 wherein the oxygen-containing gas further comprises a nucleant.
16. The process of claim 15 wherein the nucleant is selected from KCl, CsCl and CsCOOH.
17. The process of claim 1 further comprising a pressure for carrying out the oxidation reaction of below atmospheric pressure.
18. The process of claim 1 further comprising a pressure for carrying out the oxidation reaction of about 10 psig to about 200 psig.
19. The process of claim 1 wherein the reaction zone temperature ranges from at least about 650° C. to about 1800° C.
20. The process of claim 1 wherein the reaction product from step b) is in the vapor phase.