稀土在汽油车尾气净化中的应用

Application of Rare Earths in Gasoline Vehicle Exhaust After-Treatments

截至2021年底,中国的汽车保有量超过3亿辆,其中汽油车占比90%以上,是中国最重要的汽车类型。为了应对汽油车尾气中的氮氧化物(NO_(x))、碳氢化合物(HC)和一氧化碳(CO)等典型污染物,“三效催化剂”这一具有里程碑意义的汽油车尾气后处理技术被开发、应用并不断完善。新近流行的汽油缸内直喷(GDI)技术会导致显著的颗粒污染物(PM)排放,由此又催生了汽油车颗粒物过滤器(GPF)技术。上述技术的实施或多或少都需要依赖中国战略资源——稀土的参与。本文首先对各类汽油车尾气净化技术的发展进行了回顾,之后重点分析了(以CeO_(2)为主的)稀土材料在三效催化剂储氧材料、催化剂载体/贵金属稳定剂和汽油车颗粒物过滤器中的具体应用方式和效果。可以看出,随着新型稀土材料的开发和技术迭代,现代汽油车尾气净化技术正在变得越来越高效、越来越便宜。最后,本文对汽油车尾气净化用稀土材料的发展趋势进行了展望,分析了相关产业未来升级的重点和难点所在。

By the end of 2021, China′s car ownership had exceeded 300 million, among which gasoline vehicles account for more than 90%. In order to eliminate the gasoline pollutants such as nitrogen oxides(NO_(x)), hydrocarbons(HC) and carbon monoxide(CO), three-way catalysts—a landmark gasoline vehicle exhaust aftertreatment technology—was developed, applied and integrated. The currently fashionable gasoline direct injection(GDI) technology causes significant particulate matter(PM) emission, which in turn leads to the creation of gasoline particulate filter(GPF) technology. The implementation of the above technologies more or less depends on the participation of China′s strategic resources——rare earths. This paper first reviews the development of various gasoline vehicle exhaust after-treatment technologies, and then focuses on the specific application modes and effects of rare earth materials(mainly cerium dioxide) in three-way catalytic oxygen storage materials, catalyst support/noble metal stabilizers and GPFs. It can be seen that with the development and technical iteration of novel rare earth materials, modern gasoline vehicle exhaust after-treatment technologies are becoming more and more efficient and cheaper. Finally, this paper looks forward to the development trend of rare earth materials for gasoline vehicle exhaust purification, and analyzes the key points and difficulties of future upgrading of related industries.