Effect of Mn addition on the low‐temperature NH₃‐selective catalytic reduction of NO_x over Fe₂O₃/activated coke catalysts: Experiment and mechanism

Abstract

Fe2O3/activated coke (AC) and Mn–Fe2O3/AC catalysts were prepared by an impregnation method for the low‐temperature selective catalytic reduction of nitrogen oxides (NOx) with ammonia (NH3). These catalysts were characterized by X‐ray fluorescence, X‐ray diffraction, isothermal N2 adsorption/desorption, X‐ray photoelectron spectroscopy, temperature program reduction by H2, and temperature programmed desorption of NH3 methods. Experimental results show that Fe2O3/AC catalyst with Mn addition exhibits an excellent NOx conversion at low temperature. Nearly more than 94.7% NOx conversion of 8Mn6Fe/AC catalyst was obtained at 180–240°C. The results of NH3 transient reaction and adsorption capacity of NOx indicate that 8Mn6Fe/AC catalyst has the capacity to adsorb gaseous NH3 and NOx on the catalyst surface. 6Fe/AC catalyst with a certain amount addition of Mn increases the dispersion of γ‐Fe2O3 phase, and ratios of Fe3+/(Fe2+ + Fe3+) and Oβ/(Oβ + Oα) obtained good reducibility and a lot of acid sites, which play important roles in improving the NOx conversion. The influences of SO2 and H2O on the NOx conversion over 8Mn6Fe/AC catalyst were also investigated. The good H2O poisoning resistance was obtained.

Enhancement of SCR performance of monolithic Mn–Ce/Al2O3/cordierite catalysts by using modified deposition precipitation method

“…The first peak at 529.7–529.9 eV was assigned to lattice oxygen atoms (noted as O a ), the second one at 531.1–531.5 eV was attributed to surface‐absorbed oxygen (noted as O b ), and the third oxygen peak at 533.1–533.5 eV was originated from chemisorbed water (noted as O c ) . According to the literatures, O b was more active in the SCR reaction due to its higher mobility, which was beneficial to the NO oxidation into NO 2 and thus led to a fast SCR reaction . The relative concentrations of O b of 1IMP1, DP2, and MDP3 were 26.42%, 45.17%, and 70.46%, respectively, consistent with the order of the SCR activity, which meant O b played an important role in the SCR reaction of the catalysts prepared by these three methods.…”

Promotional Effect of Manganese on Selective Catalytic Reduction of NO by CO in the Presence of Excess O2 over M@La–Fe/AC (M = Mn, Ce) Catalyst

“…The observed peaks at 711.2 and 725.5 eV were attributed to the binding energies of Fe 2p 3/2 and Fe 2p 1/2 , respectively. The values of 709 and 711 eV were reported for Fe 2+ (2p 3/2 ) and Fe 3+ (2p 3/2 ), respectively [17,35,37]. The shake-up satellite peaks at 714.02, 718.57, 731.67, and 734.40 eV correspond to Fe 2p 3/2 and Fe 2p 1/2 [19].…”

Effect of pre-oxidation process on V2O5/AC catalyst for the selective catalytic reduction of NOx with NH3

“…As shown in Fig. 5a, the AC curve showed only one peak at 147 °C, while the V/AC-X samples present two broad peaks; the desorption peaks located at 147 °C and 170 °C were the physical adsorption of ammonia and the adsorption of NH 4+ at the Brønsted acid site (Yin et al 2018). After loading vanadium species, the desorption peak area increased significantly, indicating that vanadium species can provide more acidic sites on the catalyst surface, which can promote the adsorption and activation of ammonia.…”