Emission control catalysts experience degradation under the severe operating conditions which can negatively impact the product distribution and conversion. Understanding and quantifying this impact is necessary to properly design the catalyst. This study elucidates the effect of hydrothermal aging on the performance of a Pt/γ-Al₂O₃ washcoated monolith used for oxidation of ammonia and of propylene, two reaction systems pertinent to the Ammonia Slip Catalyst (ASC) and Diesel Oxidation Catalyst (DOC), respectively. The Pt/γ-Al₂O₃ catalyst was subjected to a feed stream containing H₂O at 550 °C for over 250 h. The performance of the catalyst was measured at discrete intervals as it was progressively aged. The catalyst performance results reveal for ammonia oxidation that hydrothermal aging has a negligible impact on Pt/Al₂O₃ activity for temperatures below 250 °C but a significant detrimental impact for temperatures exceeding 300 °C. A (1D + 1D) reactor model was developed to predict the decline in the observed activity with aging time. Using kinetics and catalyst characterization data, the reactor model predicts that changes in washcoat morphology during aging is likely the underlying mechanism for the decline in activity of the catalyst. The results are corroborated with testing and modeling of propylene oxidation on the Pt/Al₂O₃ catalyst.

排放控制催化剂在严格的操作条件下会发生降解，这可能会对产品的分布和转化产生负面影响。要正确设计催化剂，必须了解并量化这种影响。这项研究阐明了水热老化对用于氨和丙烯氧化的Pt / γ- Al ₂ O ₃活化涂层整料的性能的影响，这是与氨滑动催化剂（ASC）和柴油氧化催化剂（DOC）有关的两个反应系统）， 分别。使Pt / γ- Al ₂ O ₃催化剂经受含H ₂的进料流O在550°C下持续250小时以上。随着催化剂逐渐老化，以不连续的时间间隔对其进行测量。催化剂性能结果表明，对于氨氧化，水热老化对低于250°C的温度对Pt / Al ₂ O ₃活性的影响可忽略不计，而对于超过300°C的温度则有明显的不利影响。开发了一个（1D + 1D）反应堆模型，以预测观察到的活性随老化时间的下降。使用动力学和催化剂表征数据，反应器模型预测老化过程中修补基面涂层形态的变化可能是催化剂活性下降的潜在机理。该结果与在Pt / Al ₂ O上丙烯氧化的测试和建模得到了证实₃催化剂。