Study of the crystal structure effect and mechanism during chemical looping gasification of coal

Chemical looping gasification (CLG) of coal, in which oxygen is provided to coal by oxygen carriers directly, is a clean and efficient way to generate syngas. Thermo-gravimetric analysis (TGA) of lignite char with oxygen carriers was conducted in this work, and the experimental results indicated that the oxygen carriers, Ti0.5Mn0.5Fe2O4, MnFe2O4, FeTiO3 and Fe2TiO4, had a positive effect on CLG of lignite char. The effect of these oxygen carriers was discussed in the perspective of the crystal structure. XPS experiment was performed and the spectra of O 1s revealed the effect of different element on reactivity of spinel-based oxygen carriers. Five kinetic models, including Uniform Reaction (UR), Integrated Model (IM), Modified Random Pore Model (MRPM), Random Pore Model (RPM) and Modified Volumetric Model (MVM), were employed for revealing the reaction mechanism. MRPM had the highest correlation coefficient for each oxygen carrier, which means the introduction of the oxygen carriers effectively increases the active site of the reaction surface. (C) 2018 Energy Institute. Published by Elsevier Ltd. All rights reserved.