Procedure for the preparation of powders and suspensions of amorphous silicon dioxide microspheres.

摘要

A method of isolating microporous, spherical poly(silicic acid) particles from a suspension prepared by hydrolysis of tetraalkoxysilane introduced continously or portionwise into a methanolic or ethanolic solution of 1 - 5 mol l<-><1> ammonia and 2 - 12 mol l<-><1> water containing an exact number of 10<1><5> - 10<2><0> l<-><1> seed particles, by evaporation of the liquid part of the final mixture or by sedimentation in low centrifugal fields and the drying of the isolated product to give a slightly agglomerated but redispersable powder and the calcination thereof to give a slightly agglomerated but redispersable powder of compact, spherical silicon dioxide particles.