Analytical and kinetic approaches for the basic type of MgCl₂‐supported high yield catalysts

Abstract

Abstract Thermal analysis in combination with infrared spectroscopy was applied to investigate the states of ethylbenzoate (EB) and TiCl 4 in the simple type of the MgCl 2 ‐supported high‐yield catalysts. A further attempt was made to evaluate kinetic parameters in the initial stage of propylene polymerization (< 1s) by a stopped flow method. The catalysts employed in the present study were prepared by co‐grinding MgCl 2 and TiCl 4 · EB complex. Thermal analysis and infrared spectroscopy showed that TiCl 4 · EB complex decomposes during co‐grinding process. It was also indicated that EB, thus produced, has strong interaction with MgCl 2 . This was consistent with observations made by infrared spectroscopy. It was deduced that EB and TiCl 4 are supported at separate sites of MgCl 2 in the co‐ground catalyst. Kinetic parameters including rate constants of propagation ( k p ) and transfer ( k tr ), and concentration of polymerization centers ([C * ]) were determined. The values of k p and k tr remained almost constant throughout the range of co‐grinding time, but [C * ] increased with time of co‐grinding. No significant changes in the value of k tr were observed. Accordingly, the improvement of catalyst activity was attributed to an increase in [C * ] rather than k p . These results lead to the conclusion that the complex decomposes during the co‐grinding to yield EB and TiCl 4 which interact only with MgCl 2 .