Assessing the catalytic effect of coal ash constituents on the CO2 gasification rate of high ash, South African coal

The catalytic effect of inorganic species, within the ash, on the CO2 gasification of three South African coals containing similar carbon-structural properties (elemental, structural and petrographical properties) was assessed. The reactivity of the coals with a particle size between 150 and 250 μm was determined in a thermo gravimetric analyser. The reactivity was measured at temperatures between 900 and 1000 °C, pressures between 1 and 10 bar, and fractions of CO2 between 10 and 30%. For the selected coals, the reactivity decreased with ash content, and was found to be dependent on the composition of the ash. Specifically, the reactivity increased with calcium and magnesium content and alkali index.

► Catalytic effect of inherent minerals on the CO2 gasification of coal. ► Coals with similar organic and chemical properties are investigated. ► Three coals containing different mineral contents. ► Increasing amounts of catalytic active species in ash increases CO2 reactivity. ► Catalytic effect of ash quantified with Alkali index and Al2O3/SiO2 ratio.