Inert chemical looping conversion of biochar with iron ore as oxygen carrier: Products conversion kinetics and structural evolution

In this study, biochar obtained from pyrolysis of woody shavings at 550 degrees C was reacted with iron ore in N-2 to investigate its inert chemical looping conversion properties, including the gas products conversion kinetics and structural evolution process. Results found that both the release of CO and CO2 could be divided into rapid release stage and stable chemical looping reaction stage with activation energies of 17.69 and 45.65 kJ/mol, respectively. During the chemical looping process, the reaction reactivity of biochar reduced gradually with the amorphous char structure turning into fused ring structure and finally into graphite crystal structure. Simultaneously, Fe2O3 was reduced into Fe3O4, FeO and Fe. This work highlighted the chemical conversion of biochar using natural iron ore as oxygen carrier in inert N-2 atmosphere from the common in-situ gasification chemical looping process using CO2/H2O as agent.