The influence of CNTs addition on Mn-Ce/TiO2 catalyst for low-temperature NH3-SCR of NO

Abstract

Mn-Ce/TiO2 and Mn-Ce/TiO2-CNTs were tested for the low-temperature selective catalytic reduction of NO with NH3. The CNTs were in intimate contact with the catalyst surface, and the catalyst crystallinity, BET surface area, and porosity barely changed after CNTs addition. Compared to Mn-Ce/TiO2, Mn-Ce/TiO2-CNTs exhibited superior catalytic activity and N2 selectivity at 140–240 °C. High Mn4+ concentration and abundant chemisorbed oxygen species were found on the Mn-Ce/TiO2-CNTs. Monodentate nitrate species were mainly formed on Mn-Ce/TiO2-CNTs, which reacted with NH3, leading to a more reactive intermediate (Mn(n-1)+–O–NO2[NH3]2). Therefore, CNTs addition provided an enhanced favorable NOx adsorption sites resulting in high catalytic efficiency.

Keywords

• NOx
• NH3-SCR
• TiO2
• Carbon nanotubes
• NO adsorption