Kinetics and Mechanism of Catalytic Oxidation of NO in Coal Combustion Flue Gas over Co-Doped Mn–Ti Oxide Catalyst

The coprecipitation method was used to prepare Mn/Ti, Mn/Co/Ti, and Co/Ti metal oxide catalysts to oxidize NO with O2. The influence of the concentrations of NO and O2 on the oxidation of NO was investigated. Besides, the changes in the reaction rate with the particle size of the catalysts were investigated to determine the internal diffusion resistance. The surface area and microcrystalline structure of the catalysts were analyzed to investigate the impact of physical structure on SO2 poisoning in the catalyst. It was observed that Co doping in Mn/TiO2 had a favorable impact on reducing the effect of SO2 poisoning during the NO oxidation reaction. On the basis of the kinetic study, it was concluded that the reaction followed the Langmuir–Hinshelwood (L-H) mechanism, where NO and O2 were adsorbed on the catalyst, forming highly reactive NO+ and O–, which were then converted into NO2. The Co doping into the TiO2 crystal lattice increased the O2 adsorption, thus accelerating the rate of NO oxidation reaction.