Titanium-containing surface compounds have been obtained by the interaction of the silanol groups of Vulcasil with TiCl4 vapour. These substances have been used, in combination with organ-oaluminium and organo-magnesium compounds, for the polymerization of ethylene. The effects upon the catalyst activity of the reaction conditions (temperature, pressure, duration of polymerization), of the titanium amount on the Vulcasil surface and the Al:Ti and Mg:Ti ratios have been studied. The activity of the catalyst system has been shown to increase with increasing pressure up to 11 kg/cm2 and to attain its optimum value at 60°. Polymerization has been found to end 15-20 min after the introduction of the monomer. The highest yields of polymer are obtained at Mg:Ti and Al:Ti ratios of about 30. The amount of titanium on the Vulcasil surface depends on the conditions of preliminary heat-treatment of the Vulcasil and decreases from 0.63 to 0.30 mg at/g with increasing dehydroxylation temperature. Simultaneously, the yield of polymer varies within a narrow range (89-107 g/l), and the productivity increases from 21 to 35.5 kg polyethylene (PE) per 1 g of Ti. This is especially clearly expressed with the samples obtained by preliminary heat-treatment at 400-700°. © 1979.
