Aqueous methods for titanating a chromium/silica catalyst
Methods for synthesizing a water-soluble titanium-silicon complex are disclosed herein. The titanium-silicon complex can be utilized to produce titanated solid oxide supports and titanated chromium supported catalysts. The titanated chromium supported catalysts subsequently can be used to polymerize olefins to produce, for example, ethylene based homopolymer and copolymers.
1. A process for preparing a titanated chromium supported catalyst, the process comprising:
(1) contacting a silicon compound with water and an acid or a base in a solvent to form a first solution containing a partially-hydrolyzed silicon material;
(2) contacting a titanium compound with the first solution containing the partially-hydrolyzed silicon material to form a second solution containing a titanium-silicon complex; and
(3) combining a chromium-containing compound, at least a portion of the second solution containing the titanium-silicon complex, a solid support, and optionally, additional water, and drying to form the titanated chromium supported catalyst.
2. The process of claim 1 , wherein in step (1):
the silicon compound is contacted first with the solvent, followed by addition of the acid or the base, and then water to form the first solution; and
a molar ratio of water to silicon is in a range from about 0.1:1 to about 1.8:1.
3. The process of claim 1 , wherein in step (1):
the solvent comprises an alcohol;
the silicon compound comprises a silicon alkoxide, a silicon halide, a silicon hydride, a silane, a hydrocarbyl silane, a siloxane, or any combination thereof; and
a molar ratio of water to silicon is in a range from about 0.2:1 to about 0.8:1.
4. The process of claim 1 , wherein in step (2):
a molar ratio of titanium to silicon is in a range from about 0.1:1 to about 5:1; and
the titanium compound comprises a titanium alkoxide, a titanium halide, a titanium acetylacetonate, or any combination thereof.
5. The process of claim 1 , wherein in step (2):
a molar ratio of titanium to silicon is in a range from about 0.3:1 to about 1:1;
the titanium compound is water-soluble; and
the second solution containing the titanium-silicon complex does not contain a precipitate.
6. The process of claim 1 , wherein:
the process further comprises a step of combining additional water with at least a portion of the second solution containing the titanium-silicon complex prior to step (3) to form a diluted second solution containing a hydrolyzed titanium-silicon complex, wherein the amount of additional water is an amount sufficient for complete hydrolysis of the titanium-silicon complex; and
step (3) comprising combining the chromium-containing compound, at least a portion of the diluted second solution containing the hydrolyzed titanium-silicon complex, and the solid support, and drying to form the titanated chromium supported catalyst.
7. The process of claim 1 , wherein in step (3):
the titanium-silicon complex is combined with the solid support before the additional water; and
a molar ratio of additional water to silicon is at least about 2:1.
8. The process of claim 1 , wherein the solid support comprises silica, silica-alumina, silica-coated alumina, silica-titania, silica-titania-magnesia, silica-zirconia, silica-magnesia, silica-boria, aluminophosphate-silica, or any combination thereof.
9. The process of claim 1 , wherein:
the solid support comprises silica; and
drying comprises spray drying.
10. The process of claim 1 , wherein the chromium-containing compound comprises a water-soluble chromium (II) compound, a water-soluble chromium (III) compound, or any combination thereof.
11. The process of claim 1 , wherein the titanated chromium supported catalyst contains:
from about 0.5 to about 15 wt. % chromium;
from about 1 to about 10 wt. % titanium; and
less than 1 wt. % carbon;
based on the total weight of the catalyst.
12. The process of claim 1 , wherein the titanated chromium supported catalyst comprises a titanated chromium/silica catalyst.
13. The process of claim 1 , wherein the solid support comprises a zeolite.
14. The process of claim 2 , wherein:
the molar ratio of water to silicon is in a range from about 0.2:1 to about 0.8:1; and
the solid support comprises silica, silica-alumina, silica-coated alumina, silica-titania, silica-titania-magnesia, silica-zirconia, silica-magnesia, silica-boria, aluminophosphate-silica, or any combination thereof.
15. The process of claim 3 , wherein:
the molar ratio of water to silicon is in a range from about 0.3:1 to about 0.7:1; and
the solid support comprises silica, silica-alumina, silica-coated alumina, silica-titania, silica-titania-magnesia, silica-zirconia, silica-magnesia, silica-boria, aluminophosphate-silica, or any combination thereof.
16. The process of claim 4 , wherein:
the molar ratio of titanium to silicon is in a range from about 0.3:1 to about 1:1; and
the solid support is silica.
17. The process of claim 11 , wherein the titanated chromium supported catalyst is characterized by:
a total pore volume from about 0.5 to about 5 mL/g;
a BET surface area from about 200 to about 700 m 2 /g; and
a d50 average particle size from about 10 to about 500 microns.
18. A process for preparing a titanated chromium supported catalyst, the process comprising:
(1) contacting a silicon compound with water and an acid or a base in a solvent to form a first solution containing a partially-hydrolyzed silicon material;
(2) contacting a titanium compound with the first solution containing the partially-hydrolyzed silicon material to form a second solution containing a titanium-silicon complex; and
(3) combining at least a portion of the second solution containing the titanium-silicon complex, a supported chromium catalyst, and optionally, additional water, and drying to form the titanated chromium supported catalyst.
19. The process of claim 18 , wherein in step (3):
the titanium-silicon complex is combined with the supported chromium catalyst before the additional water; and
a molar ratio of additional water to silicon is at least about 10:1.
20. The process of claim 18 , wherein the supported chromium catalyst comprises chromium/silica, chromium/silica-titania, chromium/silica-titania-magnesia, chromium/silica-alumina, chromium/silica-coated alumina, chromium/aluminophosphate, or any combination thereof.
21. The process of claim 20 , wherein a molar ratio of water to silicon in step (1) is in a range from about 0.2:1 to about 0.8:1.
22. The process of claim 20 , wherein a molar ratio of titanium to silicon in step (2) is in a range from about 0.3:1 to about 1:1.
23. The process of claim 20 , wherein:
the supported chromium catalyst comprises chromium/silica; and
drying comprises spray drying.
24. The process of claim 18 , wherein:
a molar ratio of water to silicon in step (1) is in a range from about 0.1:1 to about 1.8:1;
a molar ratio of titanium to silicon in step (2) is in a range from about 0.1:1 to about 5:1;
the silicon compound comprises a silicon alkoxide, a silicon halide, a silicon hydride, a silane, a hydrocarbyl silane, a siloxane, or any combination thereof; and
the titanium compound comprises a titanium alkoxide, a titanium halide, a titanium acetylacetonate, or any combination thereof.
25. The process of claim 24 , wherein the supported chromium catalyst comprises chromium/silica, chromium/silica-titania, chromium/silica-titania-magnesia, chromium/silica-alumina, chromium/silica-coated alumina, chromium/aluminophosphate, or any combination thereof.
26. The process of claim 18 , wherein the titanated chromium supported catalyst contains:
from about 0.5 to about 15 wt. % chromium;
from about 1 to about 10 wt. % titanium; and
less than 1 wt. % carbon;
based on the total weight of the catalyst.
27. The process of claim 18 , wherein the titanated chromium supported catalyst comprises a titanated chromium/silica catalyst.