MIXED ORGANO OXIDE CHROMIUM POLYMERIZATION CATALYSTS

Supported chromium oxide catalysts are activated by calcination in dry air at 400-900 degree C, which dehydrates the carrier and binds chromium(VI) to the surface. A reduction by ethylene then provides the active species. Alternatively, the carrier can be calcined alone and afterward impregnated with an organochromium compound. Both procedures can produce an active catalyst for ethylene polymerization, but the two types differ considerably in their behavior. A third type is made by reacting an organo-chromium compound with the activated chromium oxide catalyst.