Theoretical investigations on Ziegler-Natta catalysis: models for the cocatalyst components

DFT Study of Lewis Base Interactions with the MgCl2 Surface in the Ziegler−Natta Catalytic System: Expanding the Role of the Donors

“…Overall, all the calculations have been done in this section by using the well-accepted ,− methodology of fixing all the support magnesium and chlorine atoms. While corroborations were seen between the calculated values and experiment, some discrepancies have also been observed and discussed above.…”

“…The MgCl 2 surface model that has been adopted for the calculations discussed in the previous sections keeps all the magnesium and chlorine atoms fixed. This, as mentioned in Computational Details, is the model that has been successfully employed in the past by computational groups to provide correct trends in the relative coordination energies. ,− However, as discussed in section A above, discrepancies were observed between the computational and experimental results for the 7.9 Å case. To investigate the causes of this discrepancy, the employed MgCl 2 model was modified by relaxing the surface magnesium and chlorine atoms.…”

“…First, calculations were done keeping all the atoms in the MgCl 2 lateral cuts fixed: the “Fully Fixed” model. As has been noted in several previous computational studies, this model, based on the simplifying assumption that the atoms on the surface are close in structure to the bulk, can be expected to preserve the trends in the relative coordination energies. ,− …”

“…As has been noted in several previous computational studies, this model, based on the simplifying assumption that the atoms on the surface are close in structure to the bulk, can be expected to preserve the trends in the relative coordination energies. 40,[57][58][59][60][61] Because the scope and the objective of the present work is to compare and contrast different donors, as well as compare the binding for the same donor to the same lateral cut at different interlayer distances, we believe that this is a reliable approach. Nevertheless, calculations have also been done with a "Partially Relaxed" model, where the surface magnesium and chlorine atoms were kept unfixed.…”

A DFT study on the effect of hydrogen in ethylene and propylene polymerization using a Ti-based heterogeneous Ziegler–Natta catalyst

“…Since the original discovery of the TiCl 4 /Al(C 2 H 5 ) 3 catalytic system by K. Ziegler [1] and its importance in the polymerization of propylene first noticed by G.Natta [2], the so called ZeN catalysis has had an enormous impact in the petrochemical industry [3e5]. The most popular ZeN heterogeneous system consists of TiCl 4 supported on a MgCl 2 substrate [6,7].…”