In-situ multinuclear solid-state NMR spectroscopy under continuous-flow conditions for investigations of Ziegler–Natta catalyzed propene polymerization

Abstract

Multinuclear ( 1H, 13C, 27Al) high-resolution solid-state nuclear magnetic resonance (NMR) during the continuous-flow of propene monomer was applied to analyze in-situ propene polymerization on Ziegler–Natta catalysts. A supported Ziegler catalyst activated with triethylaluminum and AA-TiCl 3 were employed as catalysts. The time-dependent change in the spectral peak intensities during the propene polymerization with both catalysts was measured using 13C CP MAS (cross-polarization with magic angle spinning) NMR and 1H MAS NMR. The states of the aluminum complex in the catalysts were studied using 27Al MAS NMR, which is sensitive to the coordination and symmetry of the local environment around the aluminum nuclei. Peculiarities of the polymerization kinetics, the crystalline states of the nascent polypropene formed on the catalyst surface, and the state of aluminum coordination and environment during the early stage of the propene polymerization under continuous-flow condition are discussed.