Catalyst for making polyethylene
AssigneeAllied-Signal Inc.
InventorsLi Wang, Roy T. Mitsche
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Abstract
The instant invention provides an olefin polymerization catalyst comprising chromium and titanium supported on silica. The catalyst is prepared with a low sodium ammonia-stabilized silica sol which has an average silicate particle size of from about 2 to about 6 nm. The catalyst produces polyethylene or a copolymer of ethylene and another olefin selected from the group consisting of the C.sub.3 to C.sub.8 mono 1-olefins, the polymer having a high melt index and a narrow molecular weight distribution.
Claims15
An olefin polymerization catalyst comprising chromium and titanium supported on silica prepared by the process comprising the steps of:
- a) preparing an aqueous solution containing water soluble chromium and titanium compounds;
- b) adding an ammonia-stabilized silica sol with an average silicate particle size of from about 2 to about 6 nm to solution of (a);
- c) adding a sufficient amount of ammonium hydroxide to the solution of (b) to form a hydrogel;
- d) aging, washing, and drying said hydrogel;
- and,
- e) removing water from the pores of said hydrogel to form said catalyst.
A process for preparing a polymerization catalyst comprising the steps of:
- a) preparing an aqueous solution containing water soluble chromium and titanium compounds;
- b) adding an ammonia-stabilized silica sol with an average silicate particle size of from about 2 to about 6 nm to said solution;
- c) adding a sufficient amount of ammonium hydroxide to form a hydrogel;
- d) aging, washing, and drying said hydrogel;
- and,
- e) removing water from the pores of said hydrogel to form said catalyst.
An olefin polymerization catalyst comprising chromium, titanium, and silica wherein the improvement comprises preparing the catalyst with an ammonia-stabilized silica sol having an average silicate particle size ranging from about 2 to about 6 nm.
Dependencies are inferred from the claim text.