System Evaluation of the HC deNOx Catalyst for Industrial Heavy-Duty Diesel Engine

1.Abstract Iridium (Ir) HC deNOx catalyst system for industrial heavy-duty diesel engine was investigated. The emission performance of the engine used for this examination satisfied EPA Tier 1 regulation. Though it was confirmed that applying the HC deNOx catalyst to Tier 1 level engine made it meet Tier 3 environmental regulation, the resulting in penalty of fuel consumption was seen as a big problem. To overcome this problem, the combined system comprising of hot EGR and Ir HC deNOx catalyst was examined. As the result of this study, the following points became clear: First, when there is high NOx concentration in front of catalyst, NOx conversion increases with the amount of HC. However, it saturates at a certain level, and after that, it gets worse. Second, when the NOx concentration at the inlet of deNOx catalyst is decreased with addition of the EGR system to base engine, the ability of NOx conversion gets worse with the decrease of NOx concentration at catalyst inlet. It is very difficult to meet more stringent regulations like EPA Tier 4 regulation with current Ir HC deNOx catalyst.