Reactivity and catalytic effect of coals during combustion: Thermogravimetric analysis

Catalytic coal combustion is a promising technology to realize efficient utilization of coal, however, the catalysis in the coal combustion process is unclear. This paper focused on the effects of two type catalysts (metal oxides and metal compounds) on the combustion reactivity of lignite, bituminous coal and anthracite using thermogravimetric analyzer, and discussed the catalytic mechanisms combining with catalytic thermal decomposition and catalytic char combustion. All catalysts decreased the ignition temperature and burnout temperature of coals to the extent of 0.25–81.25 °C, 24.75–73.25 °C, and increased the exothermic values. The catalytic effect was influenced by coal rank and had the greatest promoting effect on anthracite. Besides, the pyrolysis conversion rates of coals were increased by catalysts, resulting in ignition advance and made the subsequent reaction easier. The results of catalytic char combustion showed that both catalysts significantly reduced the ignition temperature of char, the Na2CO3 had the best catalytic effect on fixed carbon combustion, while CaO mainly affected the release of volatile matter. Finally, the catalytic mechanism in coal combustion was discussed. This article aims to provide theoretical reference for the practical comprehensive application of coal catalytic combustion. •A comprehensive study was conducted on the catalytic combustion process of coals.•All catalysts improve coal combustion reactivity and advance heat release.•The higher the fixed carbon content in coal, the better the catalytic effect.•The overall catalytic mechanism of coal combustion is proposed.