Density functional study on the role of electronic factors in variation of polymerization activity for Ziegler–Natta catalyst

Abstract

Listen

Translate article

The role of electronic factors in the variation of activity of Ziegler–Natta (ZN) catalysts having chloride, alkoxy and other ligands for ethylene and propylene polymerization has been investigated using density functional calculations at B3LYP/LANL2DZ level. The barriers for olefin insertion into [TiCl 2CH 3] + for ethylene and propylene are comparable whereas for catalysts with alkoxy and non-alkoxy ligands having varying heteroatoms, the insertion barriers for propylene are about 3–6 kcal/mol higher than the corresponding ethylene insertion barriers. This supports the experimental observation that the propylene polymerization with ZN catalyst having alkoxy and non-alkoxy ligands has very low catalytic activity as compared to that for ethylene polymerization whereas [TiCl 2CH 3] + polymerizes both ethylene and propylene.