Ambient temperature NOx emission control for lean-burn engines by electro-catalytic tubes

Lean-burn gasoline and diesel automobiles can have superior fuel efficiency but require advanced DeNO(x), technology. For a catalytic converter to be put underneath the passenger cars, it must be compact enough. Effective automotive DeNO(x), treatment should start at ambient temperature to avoid a heating period when the pollutant cannot be effectively treated. An electro-catalytic honeycomb, composed of electro-catalytic tubes, would fulfill this size requirement. This work demonstrates that effective lean DeNO(x), can be performed at ambient temperature by an electro-catalytic tube. The DeNO(x), activity is relatively insensitive to the variation of temperature from 200 to 600 C and increases slightly when temperature decreases from 200 C to ambient, but is quite sensitive to that of either the oxygen concentration or the NO concentration. When the oxygen concentration and the NO concentration increase from 0.5 to 14% and from 250 to 3800 ppm, respectively, the DeNO(x), activities increase considerably. The NO conversion also increases with decreasing NO concentration below 250 pprn, when there is zero NO2 yield; these can result in zero NO emission. (C) 2012 Elsevier B.V. All rights reserved.