MAGNESIUM-CHLORIDE SUPPORTED HIGH-MILEAGE CATALYSTS FOR OLEFIN POLYMERIZATION .1. CHEMICAL-COMPOSITION AND OXIDATION-STATES OF TITANIUM

The chemical composition of a MgCl//2-supported, high-mileage catalyst has been determined at every stage of its preparation. Ball milling of MgCl//2 with ethyl benzoate (EB) resulted in the incorporation of 95% of the EB present to give MgCl//2 multiplied by (times) EB//0//. //1//5. A mild reaction with a half-mole equivalent of p-cresol (PC) at 50 degree C for 1 h resulted in near quantitative retention of p-cresol by the support. Further reaction with TiCl//4 resulted in the incorporation of titanium of approximately 8, 38, and 54% in the oxidation states of plus 2, plus 3, and plus 4, respectively. The ratio of Al to Ti in the catalyst lies in the range of 0. 5 EN DASH 1. 0. Only 19% of all the Ti** plus **3 species in the catalyst can be observed by electron paramagnetic resonance (EPR); these are attributable to isolated Ti** plus **3 complexes. The remaining EPR silent Ti** plus **3 species are believed to be bridged to another Ti** plus **3 by Cl ligands. The total Cl content is equal to the sum of 2 multiplied by Mg plus 3 multiplied by Al plus 3. 5 multiplied by Ti. Most of the p-cresol moiety apparently disappeared from the support, leaving much of ethyl benzoate in the catalyst. Activation with AlEt//3 methyl-p-toluate complex reduces 90% of the Ti** plus **4 in the catalyst to lower oxidation states. The ester apparently moderates the alkylating power of AlEt//3 to avoid excessive formation of divalent titanium sites. There appears to be a constant fraction of one quarter - **1///5 of the titanium which is isolated and the remainder is in bridged clusters independent of the oxidation states of titanium.