Investigating Alkoxysilane Coverage and Dynamics on the (104) and (110) Surfaces of MgCl2-Supported Ziegler-Natta Catalysts

In this work, we present a systematic DFT analysis of the effect of surface coverage on the coordination properties of alkoxysilanes to the (104) and (110) surfaces of MgCl2. Furthermore, we investigated several possible migration pathways for alkoxysilane migration on the same surfaces. Our study clearly shows that complete coverage of the Mg vacancies on the surface by coordinating alkoxysilanes is hampered by steric repulsion between vicinally coordinated donor molecules. Our study clearly indicates that alkoxysilane migration between different MgCl2 monolayers on the (104) and (110) surfaces requires donor dissociation. The same holds for alkoxysilane migration on a single (110) MgCl2 monolayer. However, in the case of the (104) surface we found a very low energy pathway for alkoxysilane migration along the same monolayer.