2018 Volume 49 Issue 6 Pages 1217-1222
As the high amount of Phosphorus (included in lubricant oil) accumulates in the catalyst washcoat by the long-distance run of the vehicle, the exhaust-gas purification performance of the three-way catalyst decreases substantially. An extensive experiment was conducted to elucidate that mechanism. As a result of XRD analysis, it was clarified that Phosphorus and Cerium (included in oxygen storage components) formed CePO4 after the severe aging. Some collapse of the CeO2-ZrO2 structures by CePO4 formation causes the degradation of oxygen storage capacity (OSC) which affects NOx conversion efficiency. Furthermore, the addition of phosphorus trapper materials into the top catalyst layer demonstrated the suppression of the purification performance deterioration.
