Catalytic combustion of different additives on coal studied by thermogravimetry

The combustion process of raw coal with different additives was characterized by thermogravimetry and statistical analysis. It is found that the activation energy of raw coal can be reduced from 98.07 k J-tool-1 to 73.73, 78.50, and 76.45 kJ·mol^-1 by adding MnO₂, CaO, and CeO₂ with the mass fraction of 2%, respectively. The exothermic peak temperatures of combustion are separately lowered from 534.2 to 482.7, 489.4, and 484.9 ℃, but the additives have little effect on the exothermic peak temperature of oxidation, leading to a 30 ℃ reduction of distance between the oxidation peak and the combustion peak. The effects of additives on the activation energy and the combustion peak accord well with the Boltzmann equation fitted through experimental data. The lower the exothermic peak temperature of combustion, the smaller the activation energy is. Thus the activation energy can be approximately evaluated from the exothermic peak temperature of combustion in the differential thermal analysis curve.