This invention relates to treatment of catalyst supports.
Supported chromium oxide catalysts have become an important vehicle for polymerization of 1-olefins such as ethylene and predominantly ethylene copolymers. As originally commercialized, these polymerizations were carried out under solution conditions. However, it was early recognized that a more economical route to such polymers was to utilize a slurry system sometimes called a particle form system, wherein the polymerization is carried out at a low enough temperature that the resulting polymer is insoluble in the diluent. A great deal of technology has been developed on means to adapt catalysts to compensate for the inherent difficulty in slurry polymerization systems of achieving high enough flow in the resulting polymer. However, another polymer property which is important in many applications is the molecular weight distribution which has an effect on the response to shear. There are a substantial number of applications which require a higher shear response polymer than is normally produced with chromium catalysts in a slurry polymerization system.