MgCl2-supposed Ziegler-Natta (Z-N) catalysts containing three different Lewis bases (diisobutyl phthalate

9

9-bis (methoxymethyl) fluorine and 1

1-bis (methoxymethyl) cyclobutane) as intemal donors were prepared for pmpylene polymerization．The relationship between the structure of donors and the performance of catalysts were investigated The Z-N catalyst contmning 9

9-bis(methoxymethyl) fluorine as intemal donor and the related compounds were characterized by FTIR spectroscopy．It was found that the intemal donor in the MgCl2/TiCl4/ Donor catalvst svstem was directly coordinated to MgCl2．The introduction of intemal donors decreased the Ti content in the catalyst system．increased the catalytic activity and narrowed the molecular Hlass distribution of polymers obtained The stereospeciflcity of Z-N catalysts gready depended on the structure of electron donors．A model of muhi-active sites on heterogeneous Z-N catalyst was proposed to explain the experimental resuhs．