The atomic defects on the (104) and (110) surfaces of the MgCl2-supported Ziegler-Natta catalyst: a periodic DFT study

The MgCl2 support is widely used in the Ziegler-Natta system catalyzed olefin polymerization. In this work, three types of atomic defects on the ideal MgCl2(110) and (104) surfaces were designed, including (i) the mono-Cl vacancy, (ii) the di-Cl vacancy, and (iii) the mono-MgCl2 vacancy. The adsorption of TiCl4, ethyl benzoate (EB), and 2,2-methyl-1,3-dimethoxypropane (DMDOMe) on the ideal and atom defective MgCl2(110) and (104) surfaces was systematically investigated by using periodic DFT calculations. The adsorption of EB and DMDOMe is much stronger than that of TiCl4 on the ideal (110) and (104) surfaces. Interestingly, the atom defective surfaces, such as mono-Cl and di-Cl atom defective (110) and (104) surfaces, lead to sites for strong TiCl4 adsorption. Accordingly, a possible pathway for the formation of the Ti-alkyl active site starting from the adsorbed TiCl4 on the mono-Cl atom defective (110) surface was proposed. In addition, the adsorption behaviors of TiCl4 on the ideal and concave surfaces indicate that the monomeric TiCl4 tends to adsorb on the concave (104) surface compared to the ideal (110) surface.

Automated summary

In this study, the adsorption behaviors of TiCl4, ethyl benzoate (EB), and 2,2-methyl-1,3-dimethoxypropane (DMDOMe) on MgCl2 support surfaces were systematically investigated. It was found that atom defective surfaces have strong adsorption capability and may lead to the formation of active sites.