Development of iron ore oxygen carrier modified with biomass ash for chemical looping combustion

Natural iron ore as oxygen carrier for Chemical looping combustion (CLC) for CO2 capture has attracted increasing attention. However, the major challenge of iron ore is the relatively low reactivity. In this paper, the iron ore was combined with biomass ash to promote its performance. The reduction reactivity of the combined iron ore was determined using CO in TGA and fluidized bed. Afterwards, sewage sludge CLC in a 1 kW continuous reactor was conducted using the optimal oxygen carrier. The effect of several factors on the oxygen carrier performance was discussed, including ash type, ash content and reaction temperature. The results indicate that the iron ore performance was significantly affected by ash type. The biomass ashes in iron ore promoted the reactivity of oxygen carrier except for the Si-rich rice stalk ash which caused serious particle sintering. The rape stalk ash (RSA) exhibited the best performance, but the ash content should be lower than 20% to prevent reactivity deterioration because of serious sintering. The 20% RSA combined iron ore 20RSAIO exhibited excellent fluidization characteristic and promoted reactivity stability during continuous sludge CLC process. The interaction between sludge ash and the 2ORSAIO did not cause serious reactivity deterioration. (C) 2019 Elsevier Ltd. All rights reserved.