Chemical looping hydrogen production with modified iron ore as oxygen carriers using biomass pyrolysis gas as fuel

The chemical looping hydrogen (CLH) production was conducted in a fluidized bed reactor with the modified iron ore oxygen carriers (OCs) using simulated biomass pyrolysis gas (BPG) as fuel. Both carbon capture efficiency and hydrogen yield increased with the elevated reaction temperature in the fuel reactor (FR). As the reduction time in the FR increased, the carbon capture efficiency decreased but the hydrogen yield increased. An FR temperature of 900 °C and reduction time of 40 min in the FR were optimal conditions for CLH production. At this condition, the carbon capture efficiency for the NiO-iron ore, CuO-iron ore CeO-iron ore and iron ore were 83.29%, 82.75%, 70.05% and 40.46%, respectively. The corresponding hydrogen yield and hydrogen purity were 8.89 mmol g^-1 and 99.02%, 7.78 mmol g^-1 and 99.68%, 6.25 mmol g^-1 and 99.52%, and 2.45 mmol g^-1 and 97.46%, respectively. The presence of NiFe₂O₄, CuFe₂O₄ and CeFeO₃ in the modified iron ore samples enhanced the reactivity of the iron ore and promoted its reduction. Both NiO-iron ore and CeO₂-iron ore exhibited good cycle performance, while the sintering of the CuO-iron ore resulted in a decrease in the reactivity. Compared with the CuO-iron ore and CeO-iron ore, the NiO-iron ore was more appropriate for hydrogen production due to its high hydrogen yield and good cycle performance.