Direct NO decomposition over a Ce–Mn mixed oxide modified with alkali and alkaline earth species and CO2-TPD behavior of the catalysts

A Ce–Mn mixed oxide with the Mn/(Ce + Mn) molar ratio of 0.25 (designated as CeMn) was prepared by the glycolthermal method, and NO decomposition activities of CeMn modified with various species (alkali and alkaline earth species and noble metals) were examined. Although CeMn itself exhibited only a low activity for the direct decomposition of NO into N2 and O2, CeMn modified with alkali or alkaline earth species exhibited significant activities. The CO2-TPD experiment indicated that the NO decomposition activity of the catalysts was correlated with their basicities. The highest NO conversion was achieved by a Ba/CeMn system. The NO conversion on the Ba/CeMn catalyst increased with increasing reaction temperature, and 67% of NO conversion was attained at 800 °C. This catalyst retained a high activity (50% at 800 °C) even in the presence of 5% CO2 in the feed gas.