Simultaneous abatement of NOx and CO using tandem catalyst system via reactant- and energy- Co-promoting effect

Abstract

Although selective catalytic reduction (SCR) of NOx with NH3, CO catalytic oxidation, and selective catalytic reduction of NOx with CO have been used to control NOx and CO from mobile and industrial sources, the simultaneous removal of NOx and CO at low temperatures remains a great challenge due to the specificity of each catalytic reaction. Here, we achieve the simultaneous abatement of NOx and CO at low temperatures by skillfully utilizing a tandem catalyst system (e.g., Cu1/MnO2 and Ce-W/TiO2 as oxidation-SCR tandem catalysts). Through a series of catalytic activity evaluations and structural characterizations, we report that NO can promote the oxidation of CO due to the easier decomposition of the intermediates formed by the combination of adsorbed NO species and gaseous CO, and the faster supply of O* required for CO oxidation in CO+O2+NO2/NO atmosphere. Meanwhile, the heat released from the oxidation of CO not only accelerates the oxidation of NO in the oxidation system, but also contributes to the high reaction rate of subsequent fast NH3-SCR. Eventually, 100 % conversion of CO and 80 % conversion of NO appear at 128 and 186 °C, respectively. This work provides a new strategy for the simultaneous and efficient removal of CO and NOx at lower temperatures.