Effect of <scp>Mn</scp> addition on the low‐temperature <scp>NH₃</scp>‐selective catalytic reduction of <scp>NO_<i>x</i></scp> over <scp>Fe₂O₃</scp>/activated coke catalysts: Experiment and mechanism

Abstract

Abstract Fe 2 O 3 / activated coke (AC) and Mn–Fe 2 O 3 /AC catalysts were prepared by an impregnation method for the low‐temperature selective catalytic reduction of nitrogen oxides (NO x ) with ammonia (NH 3 ). These catalysts were characterized by X‐ray fluorescence, X‐ray diffraction, isothermal N 2 adsorption/desorption, X‐ray photoelectron spectroscopy, temperature program reduction by H 2 , and temperature programmed desorption of NH 3 methods. Experimental results show that Fe 2 O 3 /AC catalyst with Mn addition exhibits an excellent NO x conversion at low temperature. Nearly more than 94.7% NO x conversion of 8Mn6Fe/AC catalyst was obtained at 180–240°C. The results of NH 3 transient reaction and adsorption capacity of NO x indicate that 8Mn6Fe/AC catalyst has the capacity to adsorb gaseous NH 3 and NO x on the catalyst surface. 6Fe/AC catalyst with a certain amount addition of Mn increases the dispersion of γ‐Fe 2 O 3 phase, and ratios of Fe 3+ /(Fe 2+ + Fe 3+ ) and O β /(O β + O α ) obtained good reducibility and a lot of acid sites, which play important roles in improving the NO x conversion. The influences of SO 2 and H 2 O on the NO x conversion over 8Mn6Fe/AC catalyst were also investigated. The good H 2 O poisoning resistance was obtained.