Propylene polymerization on titanium‐magnesium catalysts, 2. Study of catalyst formation

Formation of a supported titanium‐magnesium catalyst for propylene polymerization was studied using highly dispersed magnesium chloride (surface area ca. 100 m2/g). By means of X‐ray diffraction, chemical analysis, and measurement of the surface area it was found that: i) interaction of ethyl benzoate (EB) with MgCl2 results in the formation of a compound EBEB·MgCl2 (1:1 by mole); ii) milling of products nEB · MgCl2 (n < 1) results in the decomposition of the lattice of the compound EB · MgCl2 and in the decrease of the size of MgCl2 crystallites; iii) treatment of the product nEB · MgCl2 with titanium tetrachloride results in the removal of a part of EB in the form of an EB·TiCl4, complex from the support, the decomposition of the lattice of the compound EB·MgCi2 an increase of the size of the MgCl2 crystallites, and a sharp increase of the surface area; iv) a small amount of EB (EB/MgCl2 = 0,1 to 0,2) considerably increases the isoptacticity of polypropylene. The high activity of catalysts prepared by milling is due to a higher surface area of these catalysts compared to unmilled samples.