Pptd. silica prodn. by hydrolysis of silicon tetra:chloride - by dropwise addn. of water or silicon tetra:chloride to other reactant which is mixed or dissolved in organic solvent

摘要

Silicic acids (I) are produced by hydrolysis of SiCl4 (II) with water in the presence of an organic solvent system (III), the novelty is that either (II) or the water is added dropwise, in pure form, to the other reactant (water or (II)) which is in the form of a mixt. or in soln. with (III). (III) is e.g. hydrocarbon, ether (e.g. THF), EtOAc, CHCl3, acetone, silicone oil, AcOH etc. or a mixt. thereof, pref. (II) is added to the aq. phase (esp. at 0-10 deg.C for prodn. of spherical (I)). USE/ADVANTAGE - The process enables the prodn. of hydrophobic pptd. silica in one step (if the solvent contains a siloxane or a silicone oil), with BET surface and particle size distribution tailored to requirements (by adjusting the process conditions), the prod. is pref. obtd. as compact 20-100 micron spheres, useful e.g. as a catalyst support, foam suppressant, matting agent, silicone rubber filler, etc.