Experimental and Kinetic Investigation on NO Reduction by Rice Husk Char and Catalytically with CO

Biomass char is accepted as an environmentally friendly energy resource, and is promising for NO removal in industrial furnaces. NO reduction with biomass char (rice husk) was investigated in a fixed-bed quartz reactor. The influence of CO concentration, reaction temperature, initial NO concentration, and char loading on the NO reduction were evaluated. The results showed that the overall NO reduction reaction was dominated by the direct reaction of NO with char without CO. Increasing CO concentration resulted in an enhanced catalytic reaction between NO and CO over the char surface and a decreased carbon consumption of char. With decreasing temperature, the influence of CO concentration on NO reduction was strengthened. Over the test temperature range, char provided a surface to catalyze the NO–CO reaction at excess CO/NO ratio. Increasing the initial NO concentration led to an increasingly significant influence on NO reduction with the enhanced CO/NO ratio. With increased char loading, the enhancement of NO reduction became unobservable for excess CO/NO ratio. Reaction orders of NO and activation energy for NO reduction by char were 0.71 and 60.21 kJ·mol−1, respectively, against 0.82 and 34.60 kJ·mol−1, respectively, for NO reduction by CO, catalyzed by char.