Role of Fe2O3 and CaCO3 on the Development of Carbon Structure of Coke and their Catalytic Activity for Gasification

Reactivity of cokes produced by pre-addition of Fe2O3 and CaCO3 to coals was investigated. Cokes with 0, 2, 5, and 10 wt% Fe2O3 and CaCO3 were produced. Fe2O3 and CaCO3 loaded cokes were deashed by hydrofluoric acid treatment and their gasification reactivity was measured and compared with Fe2O3 and CaCO3 loaded original cokes under CO2 and CO+CO2 (Fe2O3 only) mixed environment. Carbon crystallite size of the cokes and Fe/Ca loaded cokes were determined by XRD analysis and correlated with the reactivity. Addition of both Fe and Ca increased the reactivity of cokes. The observed enhancement of coke reactivity was discussed by considering the contribution from the change in cokes properties brought upon by Fe/Ca during coke making stage on reactivity and contribution from their catalytic effect in enhancing the reactivity. At lower temperatures (900 degrees C), increase in reactivity due to catalytic effect was small for Fe2O3 but significant for CaCO3.