scholarly journals Mechanistic Studies of Catalytic Reduction of Nitrogen Oxides from Diesel Engine Exhaust over Manganese and Cerium Oxide Based Catalysts

2021 ◽  
pp. 40-50
Author(s):  
Russel C. L. De Silva ◽  
Darrell P. Eyman
Keyword(s):  
Nitrogen Oxides ◽  
Catalytic Reduction ◽  
Selective Reduction ◽  
Catalyst System ◽  
Mechanistic Studies ◽  
Engine Exhaust ◽  
Catalytic Sites ◽  
Selective Reduction Of Nox ◽  
Reduction Of Nox ◽  
Cerium Catalysts

Finding a catalyst system that is effective and consistent for the selective reduction of NOx during lean exhaust conditions has been a predominant challenge to both industrial and research institutions, despite the large number of reported catalysts tested. The selective catalytic reduction of NO + NO2 (NOx) with CO and C3 hydrocarbons at low temperatures (175-225 oC) is investigated over manganese and cerium catalysts with and without the presence of a precious metal. 1% Pt/Mn/Al catalysts show promising results for the reaction, with continuous NOx conversions well more than 35% in the period extending beyond 170 hours. The synthesis technique of the catalyst and the reaction temperature greatly effects the reaction. There is no evidence of the presence of other nitrogen oxides in the products except for a very small quantity of N2O only at the beginning of the reaction. Mechanistic studies reveal manganese to be the major catalytic sites, while the platinum plays a secondary role. Mn/Ce/Al also show continuous deNOx activity with NOx conversions of 28-35%.

Investigation of the SCR Catalyst Ce-V/TiO2

2009 ◽  
Vol 610-613 ◽  
pp. 274-280
Author(s):  
Fen Wang ◽  
Xiu Feng Ren ◽  
Jian Feng Zhu ◽  
Hai Bo Yang
Keyword(s):  
Reaction Temperature ◽  
Catalytic Reduction ◽  
Sol Gel ◽  
Selective Reduction ◽  
Catalytic Performance ◽  
Scr Catalyst ◽  
Nox Conversion ◽  
Selective Reduction Of Nox ◽  
Reduction Of Nox ◽  
Catalytic Performances

The Ce-V/TiO2 catalysts with the selective catalytic reduction (SCR) were prepared by method of Sol-gel and insuccation. The phase compositions, microstructures and specific surface area of the catalysts were analyzed by XRD, SEM and BET, respectively. The effect of CeO2 and V2O5 loading and reaction temperature on the catalytic performances of the as-prepared catalysts was investigated by using the selective reduction of NOx with NH3. The results showed all the as-prepared Ce-V/TiO2 catalysts were made up of nanometer grains. Compared to conventional TiO2 catalysts, the as-prepared Ce-V/TiO2 catalysts possessed better catalytic performance, higher adsorbability and larger area of contact with reactant, which is due to large quantity surface micropores. The NOx conversion of SCR over 5wt%Ce-10wt%V/TiO2 catalysts reached 96.2% at the reaction temperature of 500 oC.

Investigation and Preparation of the SCR Catalysts Nano-Co/Ce-V-Zr-TiO2

2010 ◽  
Vol 663-665 ◽  
pp. 1097-1102
Author(s):  
Xiu Feng Ren ◽  
Fen Wang ◽  
Yuan Zhou ◽  
Hong En Nian ◽  
Yu Na Pang ◽  
...  
Keyword(s):  
Reaction Temperature ◽  
Catalytic Reduction ◽  
Sol Gel ◽  
Selective Reduction ◽  
Catalytic Performance ◽  
Scr Catalysts ◽  
Selective Reduction Of Nox ◽  
Reduction Of Nox ◽  
Co Precipitation ◽  
Catalytic Performances

The nano-Co/Ce-V-Zr-TiO2 catalysts with the selective catalytic reduction (SCR) were prepared by methods of Sol-gel, impregnation (IM) and co-precipitation (CP). The phase compositions, microstructures and specific surface area of the catalysts were analyzed by BET, XRD and SEM, respectively. The effect of CeO2, CoO, V2O5 and V2O5 loading and reaction temperature on the catalytic performances of the as-prepared catalysts was investigated by using the selective reduction of NOx with NH3. The results showed all the as-prepared Co/Ce-V-Zr-TiO2 catalysts were made up of nanometer grains. Compared to conventional TiO2 catalysts, the as-prepared Co/Ce-V-Zr-TiO2 catalysts possessed better catalytic performance, higher adsorbability and larger area of contact with reactant, which is due to large quantity surface micropores. The NOx conversion of SCR over 8 wt%Co/Ce-V-Zr-TiO2 catalysts reached 98.3% at the reaction temperature of 550 oC. Furthermore, the activity of Co/Ce-V-Zr-TiO2 catalysts were improved by the Co loading, however, further increasing the Co loading lead to decrease the catalysis activity.

scholarly journals Modeling of EPR Parameters for Cu(II): Application to the Selective Reduction of NOx Catalyzed by Cu-Zeolites

2018 ◽  
Vol 61 (9-11) ◽  
pp. 810-832 ◽  
Author(s):  
Estefanía Fernández ◽  
Marta Moreno-González ◽  
Manuel Moliner ◽  
Teresa Blasco ◽  
Mercedes Boronat ◽  
...  
Keyword(s):  
Selective Reduction ◽  
Selective Reduction Of Nox ◽  
Epr Parameters ◽  
Reduction Of Nox
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