Effect of the synthesis conditions of titanium-magnesium catalysts on the composition, structure and performance in propylene polymerization

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Supported catalysts synthesized via the interaction of Mg(OEt)2 with TiCl4 in the presence or absence of an internal stereoregulating donor (di-n-butyl phthalate), with different solvents (chlorobenzene, n-undecane, n-heptane) at different titanation temperatures have been studied by a set of physicochemical methods. Data on the chemical composition, X-ray structure and pore structure of these catalysts as well as data on their activity and stereospecificity in polymerization of propylene were obtained. Chemical composition, structure, activity and stereospecificity depend primarily on the presence of an electron donor stereoregulating component and on the solvent nature and titanation temperature. Activity of the catalysts is determined by totality of different characteristics: the chemical composition, in particular, the presence of inactive by-products like TiCl3(OEt), the MgCl2 X-ray structure and pore structure. More active catalyst which was synthesized under optimal conditions in the presence of di-n-butyl phthalate contains the minimal amount of TiCl3(OEt) by-product, and has a more ordered X-ray structure and a homogeneous mesoporous structure with a narrow mesopore size distribution.