Impregnated second valence chromium compound in supported catalyst

摘要

A chromium catalyst supported on a silica-containing base is prepared having chromium present in both the hexavalent state and a lower valent state by anhydrously impregnating a second chromium compound onto the base which already has a chromium compound having a different chromium valence than said second chromium compound. For instance, a silica titanium cogel containing a chromium compound calcined to give hexavalent chromium can be anhydrously impregnated with a pi -bonded organochromium compound such as dibenzene chromium or dicumene chromium. Resulting polymers have broad molecular weight distribution and can be made in slurry systems at a sufficiently high melt flow to be useful in applications such as blow molding of bottles and other hollow articles.