Detailed understanding of the poisoning mechanism in Diesel oxidation catalysts (DOCs) is the key to prevent long term catalyst deterioration in vehicles. The present work studies artificial phosphorus (P) poisoning methods applied to a commercial DOC. Cores of the DOC monolith were exposed to increasing amounts of P precursor by impregnation and by spraying. While impregnation leads to a homogeneous poison distribution in the catalytic layers, elemental analysis revealed that the spraying results in radial and axial P gradients that mimic the distribution of this poison previously observed in vehicle aged DOCs. The activity tests under simulated Diesel exhaust evidenced that P deposition by spraying was more detrimental than by impregnation and caused a more severe decrease in NO oxidation performance. Sequential treatments comprising exposure to P, thermal treatment and exposure to sulphur (S) interleaved by activity tests were performed to gain deeper insight into the catalyst deactivation mechanism.

详细了解柴油氧化催化剂 (DOC) 的中毒机制是防止车辆催化剂长期劣化的关键。目前的工作研究应用于商业 DOC 的人工磷 (P) 中毒方法。通过浸渍和喷涂，DOC 整体的核心暴露于越来越多的 P 前体。虽然浸渍导致催化层中的毒物分布均匀，但元素分析表明，喷涂导致径向和轴向 P 梯度，模拟先前在车辆老化 DOC 中观察到的这种毒物的分布。在模拟柴油机尾气下的活性测试表明，喷洒的 P 沉积比浸渍更有害，并导致 NO 氧化性能的更严重下降。