Kinetics of the hydrogen reduction of silica incorporating the effect of gas-volume change upon reaction

The kinetics of the reduction of SiO2 in hydrogen in the temperature range of 1285 degrees-1450 degrees C have been studied by analyzing experimental data obtained by thermogravimetry. The rate analysis was performed by the use of rate equations that incorporate the effect of the net change in the gas volume upon reaction on the interphase mass transfer rate. The calculated Gibbs-free energy and overall reaction rate at each temperature are in good agreement with the reported Gibbs free energy and the experimental data. This indicates that the overall reaction rate is controlled by the convective mass transfer in the diffusion boundary layer, and the effect of the net change in the gas volume upon reaction must be incorporated to analyze correctly the rate of the hydrogen reduction of silica.