Low temperature operation of NH₃-SCR systems for NOx abatement in lean burn and Diesel engines poses new demanding challenges due to the necessity of solving issues related to poor catalyst activity, urea injection management and system control. A typical example of these problems is represented by unconverted hydrocarbons (HCs) slip (e.g. during cold start or long idling) onto the SCR catalyst leading to a subsequent decrease of the DeNOx activity. In the present work, a detailed evaluation of the impact of different hydrocarbons (namely C₃H₆ and C₁₀H₂₂) on the performances of two new generation commercial zeolite SCR catalysts promoted with Fe and Cu is carried out by means of transient response method (TRM) experiments. Particular attention is devoted to elucidate the interaction between HCs and the typical constituents of SCR feed such as NH₃, NO, NO₂, O₂ and H₂O and their influence on the overall reactivity, in order to possibly clarify the associated mechanistic steps.

由于需要解决与不良催化剂活性，尿素喷射管理和系统控制有关的问题，在稀薄燃烧和柴油发动机中用于减少NOx的NH ₃ -SCR系统的低温运行提出了新的严峻挑战。这些问题的一个典型示例是未转化的碳氢化合物（HCs）泄漏（例如在冷启动或长时间空转期间）流到SCR催化剂上，导致随后的DeNOx活性降低。在当前的工作中，详细评估了不同碳氢化合物（即C ₃ H ₆和C ₁₀ H ₂₂）通过瞬态响应法（TRM）实验进行了两种以Fe和Cu促进的新型商用SCR催化剂的性能。为了阐明相关的机械步骤，需要特别注意阐明HC与SCR进料的典型成分（例如NH ₃，NO，NO ₂，O ₂和H ₂ O）之间的相互作用及其对总反应性的影响。 。