New synthesis of a highly active δ‐MgCl2 for MgCl2/TiCl4/AlEt3 catalytic systems

A good supporting material for Ziegler‐Natta type catalysts was obtained by reaction between powdered metallic magnesium and 1‐chloro‐n‐CmH2m+1 (m = 3–9). This reaction affords a highly disordered form of MgCl2 which was characterized by FT‐IR spectroscopy and powder X‐ray diffraction (XRD) analysis. This MgCl2 form shows a crystallographic disorder much higher than that exhibited by the products obtained following the commercial activation procedures of α‐MgCl2, either mechanical or chemical. As shown by the XRD spectra, the synthetized MgCl2 is characterized by the typical structure of the δ‐form. Therefore, this MgCl2 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‐MgCl2 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.).