Preparation of fumed silica using tetraethyl ortho silicate / effectof reaction temperature on its physical properties

Abstract

The aim of this work was to prepare fumed silica from tetraethyl orthosilicate and study
the effect of reaction temperature on physical properties of fumed silica.
This study was focused on indigenously a system built for the preparation, it consists of
four stages which these chemical reaction stage, agglomeration stage, separation stage and
calcinations stage. Chemical and physical properties of product “fumed silica” such purity
( SiO2 content ), acidity, porosity, pore volume and apparent density had been in measured
and evaluated.
The preparation step was performed by chemical reaction in various temperature
( 200 , 250 , 300 , 350 , 400 , 450 ,500 ) oC at (1) atmospheric pressure.
The chemical reaction occurred can be represented by:
Si(OC2H5)4 + 2H2O SiO2 + 4C2H5OH
After reaction the produced fumed silica is tend to agglomerate, separate from ethanol
vapour by cyclone separators, calcinated at (350 oC) to remove the residual ethanol vapour.
It was deduced that the chemical reaction at 200 oC give fumed silica with higher acidity
compered to the reaction at 500 oC, with small particle size and high surface area.ur.