The polymerization of ethylene in the presence of vanadium catalysts supported on zeolite NaY, HY and charcoal was examined. The catalysts were prepared by the incipient wetness method and characterized by a variety of techniques to determine the oxidation state of the vanadium species inside the zeolite. In all the catalysts that were prepared vanadium is not in a single oxidation state. These catalysts were active in the polymerization of ethylene with activities of the order of magnitude 105 gPE/ molV.[ M]. h for the zeolite catalysts and 103 gPE/ molV.[ M]. h for the charcoal systems. No polymer could be obtained in the absence of alkylaluminum or aluminoxane in the experimental conditions used. The kinetics of ethylene polymerization reactions using the vanadium catalysts was studied. A kinetic model based on a proposed mechanism for these reactions was used to fit the experimental data. The application of this model resulted in very good fittings and the kinetic rate constants of each elementary step could be estimated. Since the polyethylene that was produced is closely bound to the zeolite catalysts, the thermal and mechanical properties of the PE/ zeolite composites were measured, indicating that the presence of zeolite improved the mechanical properties of the polymers produced.
|Publication status||Published - 1 Jan 2006|