Characterization of Mixtures of Natural Manganese Ore with V/TiO2 in Selective Catalytic Reduction of NO with NH3

Abstract

Manganese oxides have high activity at temperatures below 200 degrees C and are currently being examined for use as selective catalytic reduction (SCR) catalysts. Natural manganese ore (NMO) is inexpensive, composed mainly of MnO2, and can be used as an SCR catalyst. However, the activity of NMO decreases significantly in the presence of moisture, and for this reason it has been difficult to utilize NMO as a commercial catalyst. The present study was carried out to increase catalyst activity at reaction temperatures below 200 degrees C using a mixture of NMO and V/TiO2. The mixture showed higher redox characteristics than V/TiO2 at low temperature, and its catalytic activity was improved over a wider temperature range (300 similar to 180 degrees C). In addition, the decrease in activity caused by moisture also declined. SCR reaction activity at low temperature was closely related with the redox characteristics of the catalyst by lattice oxygen, and the mixture of NMO with V/TiO2 improved the redox characteristics of the catalyst and consequently increased the activity at low temperature.