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

Abstract

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 molC/molsyngas, 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.