The activation of MgCl2-supported ziegler-natta catalysts: A structural investigation

A mathematical procedure for the investigation of the lattice disorder by stacking faults in polycrystalline solids has been used in studying samples of MgCl2 activated by ball milling for various times in the presence of TiCl4. These samples have been investigated by X-ray diffraction and by measurements of surface area, crystallite dimensions, Ti content after washing and catalytic activity in the polymerization of ethylene. A good relationship has been confirmed between activation time and activity; furthermore, the structural variations introduced by ball milling are mainly associated with rotational disorder of the Cl-Mg-Cl triple layers. Nevertheless, the analysis by X-ray diffraction is not unequivocal about the relationships between structure and activity: other significant parameters, such as the surface area and the porosity, are probably very important.