Investigation of potassium and copper decorations of Carajás hematite on coal-fuelled chemical looping combustion performance

Abstract Coal fuelled-chemical looping combustion (CF-CLC) is a novel and promising technology for CO2 mitigation. Reactive, cheap and environmental-friendly oxygen carriers (OC) are crutial for the development of CF-CLC. Carajas hematite is high grade iron ore with the largest reserve in the world, and its CF-CLC performance is examined in this work. Modifications of the Carajas hematite with K2CO3 and CuO were performed and the effects of the modifications were evaluated. The results show that Carajas hematite was moderately reactive and could be potential OC for CF-CLC. Decoration of the Carajas hematite with K2CO3 effectively improved carbon conversion but lowered CO2 selectivity. K2CO3 was gradually lost thus reducing the performance of the decorated hematite. In addition, hematite particles were sintered after adding K2CO3. CuO remarkably enhanced carbon conversion, reaction rate as well as CO2 selectivity, and the Cu-modified hematite remained stable and highly reactive although agglomeration occurred in CF-CLC cycles. Overall, CuO is superior to K2CO3 for modification of Carajas hematite, and the CuO-decorated hematite is suitable and promising OC for CF-CLC.