NO reduction by methane over iron oxides: Characteristics and mechanisms

• NO reduction by combination of methane and iron oxides was proposed.
• The combination of methane and iron oxides was effective to reduce NO.
• 100% NO reduction was demonstrated by 1.17% methane over iron oxides for 100 h at 1050 °C.
• More than 95% NO could be reduced by methane over iron oxides at fuel rich condition.
• Redox of iron between Fe3+ ↔ Fe2+ ↔ Fe due to methane played the critical effect for high NO reduction.

NO reduction by combination of methane and iron oxides was proposed and investigated in a one-dimensional ceramic tubular reactor at 300–1100 °C in N2 and simulated flue gas atmospheres. Iron mesh rolls were used as iron samples. The combination of methane and iron oxides was proved to have high effectiveness to reduce NO. 100% NO reduction was demonstrated by 1.17% methane over iron oxides for 100 h at 1050 °C in simulated flue gas containing 2.0% O2, 16.8% CO2 and 0.05% NO balanced by N2. More tests proved that more than 95% NO could be reduced by methane over iron oxides at fuel rich condition in simulated flue gas atmospheres. XRD analysis showed that the redox of iron between Fe3+ ↔ Fe2+ ↔ Fe due to methane played the critical effect for high NO reduction. The mechanisms involving in NO reduction by iron and iron oxides reduction by methane were discussed.

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