Abstract
The selective catalytic reduction (SCR) of NOx by $NH_3$ is well known as one of the most convenient, efficient, and economical method to prevent NOx emission in flue gas from stationary sources. The degradation of the reactivity is the obstacle for its real application, since high concentrations of sulfur dioxide and thermal factor would deactivate the catalyst. It is necessary to develop high stability of catalysts for low-temperature SCR. Among the transition metal oxides, $WO_3$ is known to exhibit high SCR activity and good thermal stability. The $MnOx-WO_3-TiO_2$ catalysts prepared by sol-gel method with various $WO_3$ contents were investigated for low-temperature SCR. These catalysts were observed in terms of micro-structure and spectroscopy analyses. The $WO_3$ catalyst as a promoter is used to enhance the thermal stability of catalyst since it increases the phase transition temperature of $TiO_2$ support. It was found that the addition of tungsten oxides not only maintained the temperature window of NO conversion but also increased the acid sites of catalyst.
