In the practical applications, a high portion of the NO_x is emitted without purification in the cold start period of engine because the selective catalytic reduction (SCR) or NO_x storage and reduction (NSR) catalysts are not warmed up. Passive NO_x absorbers (PNA) were proposed earlier to store the NO_x at low temperatures and release the stored NO_x during warm‐up period when the SCR and NSR catalysts downstream are functional, while this concept just attracted great interests recently to meet the extra stringent requirement of governmental emissions regulations. A plant of PNA catalysts, showing different NO adsorption/release characteristics, was disclosed. This review summarizes the recent progress in the development of PNA catalysts. The characteristics of NO adsorption/release on precious metal (i.e., Pt, Pd) loading Al₂O₃ support catalysts, CeO₂ support catalysts, and zeolite support catalysts are summarized and compared.

中文翻译：

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催化汽车排放控制的最新进展：低温下的被动式NO储存

在实际应用中，NO的高部_X不经纯化射出发动机的冷起动期间，因为选择性催化还原（SCR）或NO _X储存还原（NSR）催化剂不预热。被动NO _X吸收剂（PNA）提出较早存储NO _X在低温和释放所储存的NO _X在预热阶段，下游的SCR和NSR催化剂可以发挥作用，而这一概念最近刚引起人们极大的兴趣，以满足政府排放法规的严格要求。公开了显示出不同的NO吸附/释放特性的PNA催化剂工厂。这篇综述总结了PNA催化剂开发的最新进展。总结并比较了NO在负载贵金属（即Pt，Pd）的Al ₂ O ₃载体催化剂，CeO ₂载体催化剂和沸石载体催化剂上的吸附/释放特征。