Performance and mechanism study for low-temperature SCR of NO with propylene in excess oxygen over Pt/TiO2 catalyst

A 0.5 wt.% Pt/TiO2 catalyst was prepared and used for the low-temperature selective catalytic reduction (SCR) of NO with C3H6 in the presence of excess oxygen. The effects of Pt loading and O2 concentration on Pt/TiO2 catalytic performance for low-temperature SCR were investigated. It was found that optimal Pt loading was 0.5 wt.% and excess O2 favored low-temperature SCR of NOx. The mechanism of low-temperature SCR of NO with C3H6 was investigated with respect to the behavior of adsorbed species over Pt/TiO2 at 150°C using in situ DRIFTS. The results indicated that surface nitrosyl species (Ptδ+-NO and Ti3+-NO) and Pt2+-CO are main reaction intermediates during the interactions of NO, C3H6 and O2. A simplified NO decomposition mechanism for the low-temperature SCR of NO with C3H6 was proposed.