H. Weiss et al., Car-Parrinello molecular dynamics investigation of active surfaces and Ti catalytic sites in Ziegler-Natta heterogeneous catalysis, MACRO SYMP, 173, 2001, pp. 137-147
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 in
spect 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 su
pport according to the morphology of the active surfaces. Furthermore, the
activation and polymerization phases are shown to be critical in determinin
g whether or not a particular site is stable and suitable to carry out the
polymerization process. We also address the problem of regioselectivity. Fi
nally, we have attempted for the first time a first principles study of the
role of a typical donor phthalate elucidating its binding properties on th
e different substrate cuts and its behavior as a poisoning agent for the Co
rradini mononuclear active site. These studies are very preliminary.