Chemical looping reaction of methane with oxygen from La_0.8Sr_0.2FeO_3-δ and La_0.8Sr_0.2FeO_3-δ -Fe₂O₃ systems to syngas

The reaction of methane with oxygen from La_0.8Sr_0.2FeO_3-δ (LSF) and several LSF-Fe₂O₃ configurations was studied in chemical looping mode. Shell (LSF) and core (Fe₂O₃) (four catalysts called CS-3, CS-4, CS-5 and CS-6, over a range of coverage), LSF mixed uniformly with Fe₂O₃ (UM) and Fe₂O₃ (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, CO₂ and H₂ selectivity and coke formation) measured in 10 reproducible cycles. The reaction and XRD data indicate that CO₂ and steam formed by combustion of methane on Fe₂O₃ modify the phase composition of LSF, inhibits the initial LSF activity and improves the performance. Feeding a mixture containing 0.4 mol% CO₂, 10 mol% methane in nitrogen to LSF confirms the positive effect of CO₂ on the performance of LSF.