Synthesis of Both Powdered and Preformed MnO_x–CeO₂–Al₂O₃Catalysts by Self-Propagating High-Temperature Synthesis for the Selective Catalytic Reduction of NO_xwith NH₃

Abstract

MnO x –CeO 2 –Al 2 O 3 powdered and preformed catalysts were prepared through self-propagating high-temperature synthesis (SHS) and impregnation methods. Compared to the traditional impregnation method, the SHS method has a shorter catalyst preparation cycle and simpler preparation process. The characterization results showed that mixed crystals of cerium, aluminum, and manganese oxides were formed through the SHS method, the binding energy of Mn 4+ increased, and the active components were distributed uniformly. The MnO x –CeO 2 –Al 2 O 3 powdered catalyst had an extensive pore structure, with a Brunauer–Emmett–Teller surface area of approximately 136 m 2 /g, a pore volume of approximately 0.17 cm 3 /g, and an average pore diameter of approximately 5.1 nm. Furthermore, the MnO x –CeO 2 –Al 2 O 3 powdered catalyst achieved a NO x conversion higher than 80% at 100–250 °C. Coating liquids with identical metal-ion concentrations were prepared using the catalysts, and the preformed catalyst obtained through the SHS method had a higher loading capacity after one coating. The MnO x –CeO 2 –Al 2 O 3 preformed catalyst achieved a NO x conversion higher than 70% at 200–350 °C.

Structure–Activity Relationship Study of Mn/Fe Ratio Effects on Mn−Fe−Ce−Ox/γ-Al2O3 Nanocatalyst for NO Oxidation and Fast SCR Reaction

“…According to these fittings, the relevant binding energy and the respective atomic concentration of elements in diverse valence states on Mn−Fe−Ce−Ox/γ-Al2O3 surface are shown in Table 2. It can be seen from Figure 3a that the XPS spectra of Mn 2p in the investigated nanocatalyst samples were matched with two constituents, attributed to Mn 2p 3/2 (peak at around 642 eV) and Mn 2p 1/2 (peak at about 653 eV) existing in MnO x simultaneously [28]. The dissymmetric peak of Mn 2p 3/2 further confirmed the complex co-existence of manganese species in various states.…”

“…Meanwhile, the MnO 2 phase presented better a catalytic property than Mn 2 O 3 due to its lattice structure defect [50]. Therefore, Mn 4+ achieved the strongest redox ability comparing to the other valence states in MnO x -based catalysts [28]. The increase of the Mn 4+ /Mn n+ ratio in the Mn15Fe15−Ce/Al sample indicated the species transformation from Mn 3+ and Mn 2+ to Mn 4+ , and the chemical circumstance variation among the Mn10Fe20−Ce/Al, Mn15Fe15−Ce/Al and Mn20Fe10−Ce/Al samples.…”

A Critical Review of Recent Progress and Perspective in Practical Denitration Application

“…MnOx-based catalysts are currently the focus of low-temperature NH3-SCR flue gas denitrification technology research [168][169][170]. As an active component, MnOx can provide free electrons, which play an important role in the SCR process [171]. Wang et al [172] prepared MnOx catalyst with Na2CO3 as precipitator has a high specific surface area and amorphous framework MnO x -based catalysts are currently the focus of low-temperature NH 3 -SCR flue gas denitrification technology research [168][169][170].…”

“…Wang et al [172] prepared MnOx catalyst with Na2CO3 as precipitator has a high specific surface area and amorphous framework MnO x -based catalysts are currently the focus of low-temperature NH 3 -SCR flue gas denitrification technology research [168][169][170]. As an active component, MnO x can provide free electrons, which play an important role in the SCR process [171]. Wang et al [172] prepared MnO x catalyst with Na 2 CO 3 as precipitator has a high specific surface area and amorphous framework structure.…”

Effect of Calcination Temperature on the Activation Performance and Reaction Mechanism of Ce–Mn–Ru/TiO2 Catalysts for Selective Catalytic Reduction of NO with NH3

“… 9 − 11 Additionally, the temperature of the flue gas discharged from factories ranges from 100 to 120 °C following SO 2 removal, requiring reheating of the gas after desulfurization in sequence to grasp the operating temperature of the V 2 O 5 -WO 3 (MoO 3 )/TiO 2 catalyst. 12 , 13 This increases both the construction costs for and power consumption of the plant. Therefore, the development of low-temperature (<120 °C) NH 3 -SCR denitration technology is critical to achieving environmental protection requirements.…”