Patent ID: 6140264
Filing Date: 2000-10-31
Classification: C08F

Abstract:
A process conducted in a hydrocarbon solvent selected from the group consisting of pentane, hexane, octane, cyclohexane, methyl cyclohexane and hydrogenated naphtha at a temperature from 0.degree..degree.C. to 80.degree..degree.C. for preparing catalysts for the gas phase polymerization of alpha-olefins comprising in the following sequence:a) contacting a dehydrated silica support consisting essentially of dehydrated silica treated with from 0.1 to 3 weight % of an aluminum compound selected from the group consisting of trimethyl aluminum, triethyl aluminum and tributyl aluminum; withb) a magnesium compound selected from the group consisting of dibutyl magnesium and butyl-ethyl-magnesium to provide from 0.5 to 4.0 weight % of Mg based on the weight of the silica, and contacting the resulting product; withc) an aluminum compound selected from the group consisting of trimethyl aluminum, triethyl aluminum and tributyl aluminum to provide from 0.2 to 4 weight % of Al.sup.2 based on the weight of the silica and to provide a molar ratio of Mg:Al.sup.2 from 0.5:1 to 16:1 on the resulting product; and contacting the resulting product; withd) a halide selected from the group consisting of CCl.sub.4, secondary butyl chloride and tertiary butyl chloride said halide being added to the support in a quantity from 5 to 20 weight % based on the weight of the silica to provide a molar ratio of Cl to Mg from 1.5:1 to 6:1 and contacting the resulting product; withe) a titanium compound of the formula Ti(R.sup.5).sub.y (Cl).sub.z wherein each R.sup.5 is selected from the group consisting of C.sub.2-6 alkyl radicals and alkoxide radicals and a phenyl radical, y and z are 0 or an integer from 1 to 4 and the sum of y+z=4 to provide from 0.25 to 1.0 weight % of Ti based on the silica, the resulting catalyst having a molar ratio of (Al.sup.1 +Al.sup.2):Mg from 0.5:1 to 3:1; a molar ratio of Ti:Mg from 0.04:1 to 0.4:1 and a molar ratio of Ti:(Al+Mg) from 0.01:1 to 0.15:1.