Ethylene Polymerization on Coimpregnated Metallic Catalysts

The object of this work was to study the reaction rates and the properties or polymer produced in low pressure ethylene polymerization, using several coimpregnated metallic oxide catalysts.
The coimpregnated catalysts contained chromium oxide plus one of the oxides or nickel, cobalt, manganese, or iron on silica-alumina catalyst support.
The polymerization reactions were carried out by an alternating gas-liquid phase proxess with both a semi-batch operation and a continuous cyclic operation, using cyclohexane as a solvent.
To show the effects of the coimpregnated catalysts on the polymerization, the results were compared with those obtained using a "standard chromium" catalyst (chromium oxide alone on silica-alumina catalyst support).
The comparisons showed that the secondary metallic oxides, nickel, cobalt, manganese, and iron in the coimpregnated catalysts had a small negative effect on the reaction rate, that is, the yield of polymer produced in a given time was lower in the case or coimpregnated catalysts than with standard chromium catalyst. However, there were definite changes in the properties of polymer produced by the use of coimpregnated catalysts as evidenced by an appreciable increase in melt index compared with that of polymer made with standard chromium catalyst.