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

Abstract

N u m z u 41 0, Japan Synopsis Thermal analysis in combination with infrared spectroscopy was applied to investigate the states of ethylbenzoate (EB) and TiC1, in the simple type of the MgC1,-supported high-yield catalysts. A further attempt was made to evaluate kinetic parameters in the initial stage of propylene polymerization (i Is) by a stopped flow method. The catalysts employed in the present study were prepared by co-grinding MgC1, and TiCl, . EB complex. Thermal analysis and infrared spectroscopy showed that TiC1, . EB complex decomposes during co-grinding process. It was also indicated that EB, thus produced, has strong interaction with MgCl,. This was consistent with observations made by infrared spectroscopy. It was deduced that EB and TiCl, are supported at separate sites of MgCl, in the co-ground catalyst. Kinetic parameters including rate constants of propagation ( h,) and transfer (k,,), and concentration of polymerization centers ([C*]) were determined. The values of k , and k,, 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 , were observed. Accordingly, the improvement of catalyst activity was attributed to an increase in [C*] rather than k,. These results lead to the conclusion that the complex decomposes during the co-grinding to yield EB and TiC1, which interact only with MgCl,.

X-ray photoelectron spectroscopic analysis of effect of EB on electronic state of Ti species in TiCl4/MgCl2/EB Ziegler-Natta catalysts

“…It suggests EB interacts directly only with MgCl 2 and there is no direct reaction between EB and TiCl 4 in catalyst A. This result is in agreement with the results obtained by Terano [12,13] and Yang [14] .…”

External Donor Induced Direct Contact Effects on Mg(OC2H5)2‐Based Ziegler‐Natta Catalysts for Propylene Polymerization

“…It was demonstrated that an internal donor was strongly bound to the MgCl 2 support and did not interact with adsorbed TiCl 4 . [12,13] In general, donors block aspecific sites on MgCl 2 surface selectively to increase the isospecific Ti dinuclear species and coadsorb with Ti species to transform aspecific sites into isospecific sites. [14][15][16] Even though many scientists explained isospecificity increase by the existence of donors according to these results, the effects of donors are considered to be more complicated.…”

Investigation of Planar Ziegler-Natta Model Catalysts Using Attenuated Total Reflection Infrared Spectroscopy

“…IR spectroscopy has been extensively applied to Ziegler-Natta catalysts [17]. With regard to propylene polymerization catalysts, most of the work has focused on the spectral changes in the m C=O of the internal aromatic ester in various stages of catalyst preparation [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31].…”