Interactions between CO oxidation and selective catalytic reduction of NO with NH3 over Mn-based catalysts

The simultaneous reaction of CO oxidation and selective catalytic reduction of NOx with NH3 (NH3-SCR) is of great challenge in heterogeneous catalysis, especially at low temperatures, and the interaction between these two reactions is not clear. In this work, a series of alpha-MnO2-M (M = Fe, Co, Ce, Cu) nanorod catalysts were synthesized by a hydrothermal method. The alpha-MnO2-Cu nanorod catalyst showed the highest catalytic performance with over 85% NOx and CO removal efficiency from 150 to 250 degrees C. The addition of Cu species increased the redox ability, total oxygen storage, surface acidic sites and total CO adsorption capacity, which should be responsible for the enhanced SCR and CO oxidation activity of the alpha-MnO2-Cu nanorod catalyst. The interaction of CO oxidation and SCR reaction has been investigated over the alpha-MnO2-Cu nanorod catalyst. CO reduced the NO adsorption, which further inhibited the L-H mechanism, reduced the SCR activity and narrowed the temperature window, especially the reduction of N-2 selectivity. NH3 negatively affected CO oxidation by reducing the generation of the Mn-COO formate intermediate, while NO promoted CO oxidation through the decomposition of intermediates, which was formed by the combination of nitrate and nitrite with gaseous CO. When NH3 and NO existed together, CO oxidation was dominated by the promotional effect of NO.

Automated summary

The interaction between CO oxidation and NH3-SCR reaction has been studied over α-MnO2-Cu nanorod catalyst. The addition of Cu species enhances the catalytic performance and CO and NH3 have effects on CO oxidation and NO reduction.