Treatment of NO by a combination of MnO2 and a CO32--intercalated Mg-Al layered double hydroxide

We examined the treatment of NO from simulated exhaust gas using a combination of MnO2 and a CO32--intercalated Mg-Al layered double hydroxide (CO3 center dot Mg-Al LDH), and found that low removal efficiencies were obtained when CO3 center dot Mg-Al LDH was used in the absence of MnO2. The exhaust gas was circulated in a reaction tube filled with MnO2 (first step) and CO3 center dot Mg-Al LDH (second step), and the NOx removal efficiency of similar to 70% achieved at 170 degrees C at the beginning of the reaction decreased to 60% after 90 min. Compared to the case of only CO3 center dot Mg-Al LDH, the NOx removal efficiency significantly increased when both MnO2 and CO3 center dot Mg-Al LDH were employed, which was ascribed to the oxidation of NO to NO2 over MnO2 followed by the subsequent removal of NO2 by CO3 center dot Mg-Al LDH.