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

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>The high-purity syngas production with a molar ratio of H<SUB>2</SUB> to CO equal to 2 was achieved through a chemical looping process with a CH<SUB>4</SUB>-CO<SUB>2</SUB> feed mixture on a ceria-enhanced mesoporous Fe<SUB>2</SUB>O<SUB>3</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> oxygen carrier. The presence of CO<SUB>2</SUB> in the mixture feed enables the H<SUB>2</SUB>/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 CeO<SUB>2</SUB> (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 CO<SUB>2</SUB> with CH<SUB>4</SUB> and the textural property of the ceria-enhanced Fe<SUB>2</SUB>O<SUB>3</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> mesoporous oxygen carrier, the enhanced redox activity for the chemical looping process was demonstrated under the CO<SUB>2</SUB>/CH<SUB>4</SUB> feed ratio of 0.28 with the redox performance of CH<SUB>4</SUB> conversion = 93.11%, CO selectivity = 93.23%, average carbon deposit = 0.048 mol<SUB>C</SUB>/mol<SUB>syngas</SUB>, and average H<SUB>2</SUB>/CO ratio = 2.04. The fluctuation of the H<SUB>2</SUB>/CO ratio with the reaction time was minimized by adjusting the real-time CO<SUB>2</SUB>/CH<SUB>4</SUB> feed ratio and then, the consistent syngas production was realized even in the fixed bed chemical looping process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ceria-induced mesoporous Fe<SUB>2</SUB>O<SUB>3</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> (Ce/Fe = 0.15) showed the superior redox activity. </LI> <LI> The <I>meso</I>-porosity was derived from the merge of ceria into the Al<SUB>2</SUB>O<SUB>3</SUB> matrix. </LI> <LI> CO<SUB>2</SUB> was utilized as a co-feed with CH<SUB>4</SUB> in chemical looping process. </LI> <LI> Fluctuation of produced H<SUB>2</SUB>/CO ratio was minimized by adjusting CO<SUB>2</SUB>/CH<SUB>4</SUB> feed ratio. </LI> <LI> High-purity syngas with H<SUB>2</SUB>/CO ratio of 2 was produced via chemical looping process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>