Homogeneous Precipitation of Siliceous MCM-41 and Bimodal Silica

Abstract

A new procedure for synthesis of MCM-41 siliceous molecular sieves with regular morphologies and bimodal mesoporous silica was developed. It is based on the precipitation from an isotropic reaction mixture. The decrease in pH, which causes the formation of solid particles, is achieved by the hydrolysis of ethyl acetate. The procedure is excellently reproducible and enables to obtain not only siliceous MCM-41 with the highest degree of pore ordering and phase purity but also a material of a new type, viz. bimodal silica containing both the MCM-41 mesopore system and the system of larger mesopores whose size ranges from 15 to 25 nm.