POLYMERIZATION CATALYST USED FOR PRODUCING POLYOLEFINS THAT HAVE EXCELLENT COMBINED PROPERTIES

摘要

The invention relates to a method for producing a catalyst used for polymerizing olefins. The inventive method comprises the following steps: a) producing a finely divided silica xerogel, b) loading said xerogel, starting from a solution of chromium trioxide or a chromium compound that is converted to chromium trioxide under the conditions of step c), with chromium, and c) activating the resulting product in a water-free gas flow that contains oxygen in a concentration of more than 10 % by volume at a temperature of from 400 to 1100 DEG C, and doping the product in step b) or in step c) with a fluorinating agent. The invention further relates to a catalyst used for polymerizing olefins that is obtained according to the inventive method and to a method for polymerizing olefins according to which an olefin or an olefinic mixture is polymerized in the presence of a catalyst, using an inventive catalyst.