Influence of composition on the mesoporous structure of the silica gel prepared by sol–gel method

Abstract

The effect of composition on of the mesoporous structure of the silica gels prepared by sol–gel technique has been investigated. Two types of alkoxides were used simultaneously: tetraethoxysilane was used as the base alkoxide, the 3-glycidyloxypropyltrimethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, N-(3-(trimethoxysilyl)propyl)-ethylenediamine, octyltriethoxysilane were selected as the second silicate source. Experimental data were analyzed using n-way analyze of variance (linear model). The results showed that the structure and amount of the second alkoxide in the sol composition have strong influence on the pore characteristics of material. Specifically, longer and more branched chain of the second alkoxide results in larger specific surface area and wider pore diameter distribution. The chains of the second alkoxide behave as a template during gelation step, and they are fully removed from silica gel matrix during the calcination step. The samples with the highest specific surface area and total pore volume were obtained based on the mixture of octyltriethoxysilane with tetraethoxysilane.