THE PREPARATION OF POROUS, PURE SILICON DIOXIDE AND OF CHROMIUM-OXIDE-ON-SILICON DIOXIDE CATALYSTS

摘要

The invention relates to a process for the preparation of porous silicon dioxide by converting a silicon dioxide obtained by flame hydrolysis into a gel, using at least the same quantity by weight of water which is mixed with at least 15 vol.-% of an alcohol with 1-5 carbon atoms, calculated in relation to the volume of the water in the gel, and this mixture is spray-dried. The silica can then be made into a catalyst which is used in polymerizing olefins by placing on it a chromium compound and then heating in a non-reducing atmosphere.