About the active phases of KNO3/MgO for catalytic soot combustion

Reports suggest KNO3 as the active phase for the catalytic combustion of soot, through a redox mechanism with KNO2. Previously, the high activity of KNO3 for coal gasification (mechanism similar to that of soot combustion) was attributed to decomposition into active KxOy (y\x) compounds. In this work, TGA-MS assays of carbothermic reduction using the KNO3/MgO catalyst showed decomposition into NOx, (to which starting of CB combustion is attributed) and potassium oxide, thus disregarding possible redox cycles KNO3/KNO2. Consecutive assays of carbothermic reduction and TPO in a fixed bed reactor showed the potassium oxides as the main active phases of these catalysts.