Promotional mechanisms of activity and SO 2 tolerance of Co- or Ni-doped MnOx-CeO 2 catalysts for SCR of NOx with NH 3 at low temperature

Molybdenum modified Montmonrillonite clay as an efficient catalyst for low temperature NH3‐SCR

“…This peak could be assigned to bidentate and/or monodentate nitrate species, indicating the NO were oxidized into nitrate species and adsorbed on the surface. Peak at 1260 cm −1 would be ascribed to the bidentate nitrate and/or bridged nitrate species . For sample Mo, a positive band centered around 2300 cm −1 was detected, which was related to be the unique and strong interaction between Mo and nitrate species.…”

“…The v , v 2 , v 3 , u, u 2 , and u 3 bands could be attributed to surface Ce 4+ species with 3d 10 4f 0 electronic state, whereas v 1 and u 1 bands could be ascribed to surface Ce 3+ species with 3d 10 4f 0 electronic state. The relative content of Ce 3+ was determined by Ce 3+ /(Ce 3+ + Ce 4+ ), where Ce 3+ = (u 1 + v) and Ce 4+ = (u 3 + u 2 + u + v 3 + v 2 + v). The calculated percentages of Ce 3+ were 25.7 and 31.1% for sample blank and Mo, respectively.…”

“…NO x are emitted from the stationary and mobile exhaust, such as the coal fired power plants, cement, steel manufacturing factories and motor vehicles. The selective catalytic reduction of NO x to N 2 with NH 3 (NH 3 ‐SCR) is an effective technique for NO x elimination . The commercial Vanadium‐based NH 3 ‐SCR catalyst, such as V 2 O 5 ‐WO 3 (MoO 3 )/TiO 2 , operates in a narrow reaction temperature window of 300–400 °C, hence, the SCR catalyst units need to be installed in the upstream of the desulfurizers and dust removal devices.…”

“…The selective catalytic reduction of NO x to N 2 with NH 3 (NH 3 -SCR) is an effective technique for NO x elimination. [1][2][3] The commercial Vanadiumbased NH 3 -SCR catalyst, such as V 2 O 5 -WO 3 (MoO 3 )/TiO 2 , operates in a narrow reaction temperature window of 300-400°C, hence, the SCR catalyst units need to be installed in the upstream of the desulfurizers and dust removal devices. However, this setup can cause some problems, such as the oxidation of SO 2 to SO 3 , corrosion of the downstream devices and the deactivation of catalysts due to dust and alkali metals deposition.…”

Sulfur and Water Resistance of Mn-Based Catalysts for Low-Temperature Selective Catalytic Reduction of NOx: A Review

“…As shown in Figure 15, the NO conversion was kept at around 70% in the presence of SO 2 and H 2 O and recovered to almost the original level within less than 3 hafter SO 2 and H 2 O were removed. Gao et al [39] found that the SCR pathways over MnO x -CeO 2 catalyst are based on the adsorption, activation, and reaction of monodentate nitrite species and coordinated NH 3 species, and these species are significantly inhibited by SO 2 through competitive adsorption. In contrast, over Co-and Ni-doped MnO x -CeO 2 catalysts, the primary NO x adsorbed species are in the form of bidentate nitrate without the influence by SO 2 .…”