Influence of Internal Donors on the Performance and Structure of MgCl2 Supported Titanium Catalysts for Propylene Polymerization

摘要

An insight on the influence of ethyl benzoate (EB) and diisobutyl phthalate (DIBP) as internal donors, differing in coordination nature on the structural aspects Of MgCl2 matrix in high-performance MgCl2-supported titanium catalysts was developed using FTIR spectroscopy and WAXD studies. The analysis of the >C=O stretching IR band of internal donors showed their coordination to (104) and (110) lateral cuts Of MgCl2 matrix. Transformation of magnesium ethoxide {Mg(OEt)(2)} to MgCl2 during catalyst preparation resulted in different MgCl2 phases, namely the alpha-form, beta-form, and the disordered delta-form, which were analyzed by WAXD studies. The results from WAXD showed the relative preference of alpha-form over beta-form in case of DIBP-based catalysts, which might be due to interlayer bridging between adjacent layers due to the bidendate nature of DIBP. This can be one of the reasons for the high productivity of dialkylphthalate-based catalysts in comparison to ethyl-benzoate-based catalyst systems.