Effects of added CO₂ and H₂ on the direct decomposition of NO over BaMnO₃-based perovskite oxide

N₂ yield on Ba_0.8La_0.2Mn _0.8Mg_0.2O₃ decreased from 70% to 30% on the addition of 1% CO₂, which is a much larger negative effect than that seen with O₂. The CO₂ negative effects are not permanent and this may result from the inhibition of NO adsorption. Co-feeding of H ₂ as a reductant is effective for increasing NO conversion. This suggests that the catalyst surface was covered with strongly adsorbed nitrate or nitride species which formed by adsorption of NO on oxygen formed by the decomposition of NO, and the removal of this surface species might be the most important step for the NO decomposition reaction. Co-feeding of H₂ is also effective for increasing the NO decomposition activity in the presence of CO₂. The reaction mechanism was studied by IR measurements which also revealed that the surface of the catalyst was covered with strongly bound nitrate species (NO₃^-). The addition of H₂ to the reaction mixture is effective for NO₃^- removal and so accelerates the NO decomposition under coexistence of CO₂.