Methods of preparing a catalyst

1. A method of preparing a catalyst comprising:

contacting an acidic colloidal silica suspension with a titanium-containing compound to form a mixture;

adjusting the pH of the mixture to about neutral to form a catalyst support; and

contacting the catalyst support with a chromium-containing compound to form a chromium-supported catalyst, wherein the catalyst and/or catalyst support is not alkaline aged.

2. The method of claim 1 wherein the colloidal silica suspension comprises silica particles with a particle diameter of from about 1 nm to about 100 nm.

3. The method of claim 1 wherein the colloidal silica suspension has silica present in an amount of greater than about 10 wt. % based on the total weight of the suspension.

4. The method of claim 1 wherein the colloidal silica suspension has sodium present in an amount of less than about 0.5 wt. %.

5. The method of claim 1 wherein the titanium-containing compound comprises trivalent titanium, tetravalent titanium, or both.

6. The method of claim 5 wherein the tetravalent titanium comprises TiCl 4 , TiOSO 4 , TiBr 4 , or combinations thereof.

7. The method of claim 1 wherein a percentage titanium in the catalyst support is from about 0.1 wt. % to about 10 wt. % based on the final weight of the catalyst support.

8. The method of claim 1 wherein the chromium-containing compound comprises a water-soluble compound or a hydrocarbon-soluble compound.

9. The method of claim 8 wherein the water-soluble compound comprises chromium trioxide, chromium acetate, chromium nitrate, or combinations thereof.

10. The method of claim 8 wherein the hydrocarbon-soluble compound comprises tertiary butyl chromate, a diarene chromium ( 0 ) compound, biscyclopentadienyl chromium(II), chromium (III) acetylacetonate, or combinations thereof.

11. The method of claim 1 wherein the chromium is present in an amount of from about 0.01 wt. % to about 10 wt. % based on the final weight of the catalyst.

12. The method of claim 1 wherein the catalyst and/or catalyst support is not treated to reduce the amount of sodium present.

13. A method of preparing a catalyst comprising:

contacting a colloidal silica suspension with a titanium-containing compound under acidic conditions to form a mixture, wherein the colloidal silica suspension has silica present in an amount of greater than about 20 wt. % based on the total weight of the suspension;

contacting the mixture with a basic material in an amount sufficient to increase the pH of the mixture to about 7 to form a catalyst support; and

contacting the catalyst support with a chromium-containing compound to form a chromium-supported catalyst.

14. The method of claim 13 wherein sodium is present in an amount of less of than about 0.5 wt. % based on the total weight of the catalyst support.

15. The method of claim 13 wherein a percentage titanium in the catalyst support is from about 0.1 wt. % to about 10 wt. % based on the final weight of the catalyst support.

16. The chromium-containing catalyst prepared by the method of claim 1 .

17. The method of claim 1 , further comprising contacting the chromium-containing catalyst with ethylene and an optional comonomer under conditions suitable for the formation of an ethylene polymer.

18. The method of claim 13 wherein the titanium-containing compound comprises trivalent titanium, tetravalent titanium, or both.

19. The method of claim 18 wherein the tetravalent titanium comprises TiCl 4 , TiOSO 4 , TiBr 4 , or combinations thereof.

20. The method of claim 13 wherein the chromium-containing compound comprises a water-soluble compound or a hydrocarbon-soluble compound.