Kinetics of Hematite to Wüstite by Hydrogen for Chemical Looping Combustion

Abstract

Kinetics analysis of hematite (Fe2O3) reduction by hydrogen was evaluated by the thermogravimetric analyser (TGA) in the temperature range of 700–950 °C, using continuous streams of 5, 10, and 20% H2 concentrations in N2. A number of kinetic models have been considered, including the single and multi-step models to describe the experimental reduction data. The details of nucleation and growth during the isothermal reduction are described in terms of the local Johnson–Mehl–Avrami (JMA) exponent and local activation energy. The variations of n values (JMA exponent) and activation energies for the reduction conversion indicate the presence of the multi-step reaction process. The reduction was shown to be one-dimensional (1D) growth with a decrease in the nucleation rate.