Chemical looping reaction of methane with oxygen from La0.8Sr0.2FeO3-δ and La0.8Sr0.2FeO3-δ -Fe2O3 systems to syngas

Abstract

The reaction of methane with oxygen from La 0.8 Sr 0.2 FeO 3-δ (LSF) and several LSF-Fe 2 O 3 configurations was studied in chemical looping mode. Shell (LSF) and core (Fe 2 O 3 ) (four catalysts called CS-3, CS-4, CS-5 and CS-6, over a range of coverage), LSF mixed uniformly with Fe 2 O 3 (UM) and Fe 2 O 3 (front) followed by LSF (PIS) were packed in a tubular reactor. The reaction was conducted at 900 °C and weight hourly space velocity (g methane/g catalyst/h) of 3 h −1 in 20 min reduction (10 mol% methane in nitrogen) and 20 min oxidation (10 mol% oxygen in nitrogen) cycles. LSF, CS, UM and PIS configurations yielded a significantly different performance (methane conversion, CO, CO 2 and H 2 selectivity and coke formation) measured in 10 reproducible cycles. The reaction and XRD data indicate that CO 2 and steam formed by combustion of methane on Fe 2 O 3 modify the phase composition of LSF, inhibits the initial LSF activity and improves the performance. Feeding a mixture containing 0.4 mol% CO 2 , 10 mol% methane in nitrogen to LSF confirms the positive effect of CO 2 on the performance of LSF.