NO reduction by methane over iron oxides and the mechanism

NO reduction by methane over iron oxides( fully oxidized iron mesh roll)was experimentally investigated in an one-dimensional electrically heated temperature programmed ceramic tubular reactor at 300~1 050 ℃ in N₂ atmosphere. The NO reduction efficiency, CO formation, the components variation and microstructures of the iron sample after reaction were measured. The reaction mechanism of NO reduction by methane over iron oxides was proposed. A durable NO reduction by methane over iron oxides in simulated flue gas was conducted at 1 000 ℃. Results showed that methane was very effective to reduce NO over iron oxides. In N₂ atmosphere, 100% NO reduction efficiency was achieved when temperature was above 850 ℃. In simulated flue gas, very good durable performance was demonstrated. 1.17% vol. methane could reduce 100% NO over 100 h at 1 000 ℃ in simulated flue gas which contained 2.0% O₂, 16.8% CO₂ and 524×10^-6 NO in N₂ base. Research results on the mechanism showed that NO was reduced with methane via two major routes: one is by reburning while the other is methane reduced iron oxides to metallic iron through redox reactions and then NO was reduced by metallic iron. The latter mechanism was believed to play the major role of NO reduction.