The combustion and gasification of five coals in air and CO2, respectively, have been carried out in a wide temperature range between 500 and 1500°C to examine the effects of coal rank and catalysis by mineral matter. It was found that the catalytic effect of mineral matter determined the reactivity of coal in the region where the rate was controlled by chemical reaction. At high temperature where external mass diffusion is dominant, the order of reactivity among five coals decreased with increasing coal rank. Obviously, the chemistry is still important to some extent in the latter high temperature region; the reactivity depends on the type of coal, and there is some catalytic effect by mineral species.
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