Enhanced soot oxidation by lattice oxygen via La3+-doped CeO2

An advanced TAP reactor is used for the first time to study catalysed soot oxidation with labelled oxygen. In the absence of catalyst, oxidation starts above 500 °C, and mainly labelled oxidation species (CO and CO2) were found. In the presence of catalyst, it is shown that the gas-phase labelled oxygen replaces nonlabelled lattice oxygen, creating the highly active nonlabelled oxygen. This highly active nonlabelled oxygen reacts with soot, giving CO and CO2. The creation of such active oxygen species starts from 400 °C and thereby decreases the soot oxidation temperature. CeO2-5La produces more such active species, for example, leading to 98% oxygen conversion at 400 °C compared with 37% over CeO2 alone under identical circumstances.