Method for producing dual zone materials by catalyzed halosilylation

摘要

Dual zone porous materials having an external zone and an internal zone are prepared by contacting a suspension of a porous support, such as particulate silica, in a solvent with a halosilane and a catalyst for the halosilane in order to form first silyl groups predominantly on the external surfaces of the porous support. Preferably thereafter the porous support is contacted with a silane having second silyl groups in order to a form second silyl groups predominantly on the internal surfaces.