Promotion of Phosphorus on Carbon Supports for MnO_x−CeO₂ Catalysts in Low‐Temperature NH₃−SCR with Enhanced SO₂ Resistance

Abstract

MnOx−CeO2/P‐CA catalysts were prepared via incipient wetness impregnation of Mn(NO3)2 ⋅ 4H2O and Ce(NO3)3 ⋅ 6H2O over phosphorus‐doped carbon aerogels (P‐CA) for selective catalytic reduction of NO by NH3 (NH3−SCR). The results show that P doping on carbon support significantly promotes the NH3−SCR performance of MnOx−CeO2/P‐CA catalysts. P modification can improve the hydrophilicity of carbon support and facilitate the dispersion of MnOx−CeO2 components on carbon surface, which enhances the electronic interactions between MnOx and CeO2. The optimal catalyst 10 %MnOx−CeO2/P‐CA shows higher surface acidity, more Mn4+ and Ce3+, and a larger amount of surface chemisorbed oxygen (Oα) than that of 10 %MnOx−CeO2/CA catalyst. As a result, even though in the company of SO2, more NO can be adsorbed and oxidized over the 10 %MnOx−CeO2/P‐CA catalyst to generate more NO complexes, alleviating the suppression of SO2 on the SCR reaction via Langmuir‐Hinshelwood (L−H) mechanism, and thus the SO2 resistance is enhanced.

Cerium Oxide Nanoparticles Confined in Doped Mesoporous Carbons: A Strategy to Produce Catalysts for Imine Synthesis

“…Another reason can be the high concentration of highly reactive O surf species or functional groups on the doped supports’ surface, which can interact with H 2 at measurement conditions, providing additional gas consumption. This is an important aspect, especially in the case of the P-containing system, where P-groups such as C–O–P and C 3 –PO can suffer a reduction process where C 3 –PO transforms into C 3 –P and further to elemental P at a temperature of 400–600 °C. , The much lower intensity of the reduction peak for this system can be attributed to the presence of cerium in significant amounts as +3 ions in a hardly reducible CePO 4 . The oxygenated species that were observed on the XPS spectra and FTIR, such as phenol, ether, and carbonyl groups, can also be decomposed in H 2 in the temperature range of 600–750 °C …”

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

“…At present, the most common synthetic methods are impregnation and deposition precipitation. The enrichment of carbon support by completely immersing and mixing it with a metal precursor (i.e., copper nitrate solution) is called wet pore volume impregnation [108]. The MnO x -CeO 2 /P-CA catalysts were prepared via incipient wetness impregnation using Mn(NO 3 ) 2 •4H 2 O and Ce(NO 3 ) 3 •6H 2 O as precursors on phosphorusdoped carbon aerogels (P-CA) for NH 3 -SCR of NO.…”