Chemical looping partial oxidation of methane with CO₂ utilization on the ceria-enhanced mesoporous Fe₂O₃ oxygen carrier

The high-purity syngas production with a molar ratio of H₂ to CO equal to 2 was achieved through a chemical looping process with a CH₄-CO₂ feed mixture on a ceria-enhanced mesoporous Fe₂O₃/Al₂O₃ oxygen carrier. The presence of CO₂ in the mixture feed enables the H₂/CO ratio to be maintained as 2 desirable for the syngas-to-liquid hydrocarbon process by suppressing the methane decomposition even when the amount of reducible oxygen carrier was sufficiently small. By incorporating a small amount of CeO₂ (molar Ce/Fe ratio = 0.15) to the iron oxide mesoporous oxygen carrier by the sol-gel method, the syngas selectivity also increased although the amount of reducible oxygen was large enough to cause the total combustion. Due to the co-feeding of CO₂ with CH₄ and the textural property of the ceria-enhanced Fe₂O₃/Al₂O₃ mesoporous oxygen carrier, the enhanced redox activity for the chemical looping process was demonstrated under the CO₂/CH₄ feed ratio of 0.28 with the redox performance of CH₄ conversion = 93.11%, CO selectivity = 93.23%, average carbon deposit = 0.048 mol_C/mol_syngas, and average H₂/CO ratio = 2.04. The fluctuation of the H₂/CO ratio with the reaction time was minimized by adjusting the real-time CO₂/CH₄ feed ratio and then, the consistent syngas production was realized even in the fixed bed chemical looping process.