New synthesis of a highly active δ‐MgCl 2 for MgCl 2 /TiCl 4 /AlEt 3 catalytic systems

A good supporting material for Ziegler‐Natta type catalysts was obtained by reaction between powdered metallic magnesium and 1‐chloro‐ n ‐C m H 2 m +1 ( m = 3–9). This reaction affords a highly disordered form of MgCl 2 which was characterized by FT‐IR spectroscopy and powder X‐ray diffraction (XRD) analysis. This MgCl 2 form shows a crystallographic disorder much higher than that exhibited by the products obtained following the commercial activation procedures of α‐MgCl 2 , either mechanical or chemical. As shown by the XRD spectra, the synthetized MgCl 2 is characterized by the typical structure of the δ‐form. Therefore, this MgCl 2 form, in view of its highly disordered structure, appears as a promising material for the preparation of active supported Ziegler‐Natta type catalysts. Thus, by titanation of the obtained δ‐MgCl 2 we have prepared some supported catalysts which have been tested in the slurry propene polymerizations, showing high activity (136000–138000 gPP/gTi) and good stereoselectivity (82–88% I.I.).