NH3-NO SCR Catalysts for Engine Exhaust Gases Abatement: Replacement of Toxic V2O5 with MnOx to Improve the Environmental Sustainability

Abstract

Mn-WO3/TiO2 catalysts were investigated for Selective Catalytic Reduction (SCR) of NO with NH3. The catalysts were synthesized by wetness impregnation method with different Mn loadings (1.5-3-12 wt%) on 8wt%WO3/TiO2. All three catalysts were compared with 8wt%WO3/TiO2 and bare MnOx oxide, used as references. The 1.5wt%Mn-8wt%WO3/TiO2 exhibited the highest performance in NO conversion and N2 selectivity. A commercial catalyst, based on titania supported vanadia and tungsta, (V2O5-WO3/TiO2), widely used for its high efficiency, was also investigated in the present work. The morphological, structural, redox and electronic properties of the catalysts and their thermal stability were studied by several techniques (N2 adsorption/desorption, X-ray diffraction, H2 temperature-programmed reduction, NH3 temperature programmed desorption, X-ray photoelectron spectroscopy).The aim of this paper is to study the effect of different Mn loadings on 8wt%WO3/TiO2 with the ambition to obtain highly active and selective catalysts in a large window of temperature. The replacement of toxic vanadium used in the classic V2O5-WO3/TiO2 catalyst with MnOx in the best performing catalyst, 1.5wt%Mn-8wt%WO3/TiO2, represents an important achievement to improve the environmental sustainability.

Influence of Y Doping on Catalytic Activity of CeO2, MnOx, and CeMnOx Catalysts for Selective Catalytic Reduction of NO by NH3

“…The observed decrease in N 2 selectivity and N 2 yield registered for the CeO 2 , MnO x , and CeMnO x oxides and the corresponding Y-doped samples can be attributed to the competitive oxidation of ammonia (NH 3 -SCO) catalyzed by manganese [49] and cerium oxides, which leads to the formation of NO, NO 2 , and N 2 O and consequently decreases the selectivity. To confirm this hypothesis, Figure 7 presents the temperature dependencies of NH 3 , NO, NO 2 , and N 2 O concentrations for the most efficient CeMnO x , Y-CeMnO x , and Y/CeMnO x samples.…”

Unraveling the Effect of Mo Dopant in Fe2O3 Catalyst for Selective Catalytic Reduction of Nitric Oxide with NH3

“…Substitutes for the V 2 O 5 –WO 3 /TiO 2 system have been systematically investigated in the context of SCR reactions. Transition-metal oxides, including Fe 2 O 3 , − MnO 2 , − and CeO 2 , − have garnered attention due to their advantages, such as cost-effectiveness, versatile microstructures, excellent thermal stability, and resistance to poisoning. Fe 2 O 3 has emerged as a promising candidate for SCR processes among these metal oxides .…”