Understanding the Role of Sulfonyl Amine Donors in Propylene Polymerization Using MgCl₂-Supported Ziegler–Natta Catalyst

Abstract

Ziegler−Natta catalysts are one of the mainly used industrial catalysts for the large-scale production of polyolefins. As one of the important components in a Ziegler−Natta catalyst, the internal donor and external donor pair is responsible for increasing the stereoregularity of polypropylene. In this work, a series of sulfonyl amine internal donors were systematically investigated by density functional theory (DFT) calculations. The adsorption behavior of the sulfonyl aromatic amine BTFMSPA-m-Cl indicates that the O atom exhibited an excellent coordinating affinity to the 4-coordinated Mg atoms on the MgCl 2 (110) surface among the three functional atoms (F, Cl, O). In addition, the substituents have a great influence on the adsorption behavior of the sulfonyl amines. The functional atom of the substituent (Cl or OMe) in the phenyl ring and the oxygen of the sulfonyl group tend to form a more stable bridge-coordination (Cl-Mg1,Mg2-O3, or O-Mg1,Mg2-O3) than the chelate-coordination (O1-Mg2-O2). In all considered internal donors, the stereoselectivity of the Ti active site can be greatly enhanced in the presence of BTFMSPA-m-Cl, which presumably results from the steric hindrance around the Ti active site caused by the bridge-coadsorbed BTFMSPA-m-Cl.

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

“…However, on three kinds of atom defective (110) surfaces and the D104-1 surface, EB shows stronger adsorption than DMDOMe due to the interaction between the phenyl ring and the surface Mg atom. 34…”

“…S5c in the ESI †). 34 The interaction between the Mg atom and the phenyl ring also helps EB donor to stabilize the D104-1 surface through the bidentate mode (Fig. 8d).…”

“…However, on three kinds of atom defective (110) surfaces and the D104-1 surface, EB shows stronger adsorption than DMDOMe due to the interaction between the phenyl ring and the surface Mg atom. 34 Briefly, on the ideal (110) and (104) surfaces, the adsorption of internal donors EB and DMDOMe are more preferential than the monomeric TiCl 4 molecule (Table 2). By contrast, on the mono-Cl and di-Cl atom defective (110) and (104) surfaces involving the unsaturated 3-coordinated Mg atoms, the TiCl 4 molecule shows much stronger adsorption than EB and DMDOMe donors.…”

“…So far, most studies have focused on the ideal (110) and (104) MgCl 2 surfaces. 19–34 However, it should be noted that surface defects, such as edges, corners, vacancies, steps, etc. , could be formed during the synthesis of the Ziegler–Natta catalyst under extremely drastic conditions.…”

“…So far, most studies have focused on the ideal (110) and (104) MgCl 2 surfaces. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] However, it should be noted that surface defects, such as edges, corners, vacancies, steps, etc., could be formed during the synthesis of the Ziegler-Natta catalyst under extremely drastic conditions. 16,18,[35][36][37][38][39][40][41] Experiments have confirmed the existence of edge crystallites on the MgCl 2 support by atomic force microscopy (AFM), scanning electron microscopy (SEM), and HR-TEM.…”