The enhanced resistance to P species of an Mn–Ti catalyst for selective catalytic reduction of NOx with NH3 by the modification with Mo

Abstract

Phosphorous has a deactivation effect on an SCR catalyst. In this study, the effect of Mo modification on the resistance to P species of a Mn–Ti catalyst for selective catalytic reduction of NO_x with NH₃ was investigated. It was found that the addition of Mo could greatly improve the P species tolerance of the Mn–Ti catalyst. From the characterization results of BET, XRD, H₂-TPR, NH₃-TPD and XPS, it could be concluded that the modification of the Mn–Ti catalyst by Mo could enhance its specific surface area, redox ability and NH₃ adsorption capacity, along with the generation of more surface chemisorbed oxygen species, as a result, greatly enhancing the P species resistance of the Mn–Ti catalyst. The results of an in situ DRIFT study indicated that the NH₃-SCR reactions over Mn–Ti and Mn–Mo–Ti catalysts were governed by L–H mechanism (≤200 °C) and E–R mechanism (>200 °C) respectively.