Ethylene was polymerized with the catalytic systems Cp2ZrCl2/SiO2 and Cp2ZrCl2/MAO/SiO2. A experimental planning model was developed in order to identify the best conditions for the preparation of metallocene heterogeneous catalysts. The variables used were methylaluminoxane (MAO) concentration of the support treatment, concentration and temperature of metallocene immobilization. The supported catalysts were analyzed by inductively coupled plasma emission spectometry and the polyethylene (PE) produced was characterized by gel permeation calorimetry (GPC) and differential scanning calorimetry (DSC). It was observed that the higher the zirconium concentration fixed on the support surface, the lower the catalyst activity, in the studied variables range.
Silica; heterogeneous catalyst; metallocene; polyethylene
