Car-parrinello molecular dynamics investigation of active surfaces and Ti catalytic sites in Ziegler-Natta heterogeneous catalysis

A first principles molecular dynamics study of various active surfaces and Ti catalytic sites is presented. We first review some of our recent results about MgCl2 lateral cuts acting as a support for Ti catalytic sites and inspect the structure and stability of the standard binuclear model. We find that catalytic adducts TiCl4 and Ti2Cl6, which are the standard precursors of the active catalytic system, can bind more or less efficiently to the support according to the morphology of the active surfaces. Furthermore, the activation and polymerization phases are shown to be critical in determining whether or not a particular site is stable and suitable to carry out the polymerization process. We also address the problem of regioselectivity. Finally, we have attempted for the first time a first principles study of the role of a typical donor phthalate elucidating its binding properties on the different substrate cuts and its behavior as a poisoning agent for the Corradini mononuclear active site. These studies are very preliminary.