Increasing environmental concerns and stringent regulations have spurred the development and implementation of advanced emission control technologies that incorporate specialty zeolites as catalysts and/or adsorbents. For on-road heavy-duty diesel engines, the Japan 09 and US 2010 legislations for nitrogen oxides (NOx) and particulate matter have been in effect for a few years, and Euro VI legislation is currently being implemented. New legislations for off-road diesel engines (Tier 4 final) are also currently being implemented in the US. Urea selective catalytic reduction (urea-SCR) is one of the leading technologies for meeting these stringent NOx regulations.Microporous materials containing either Fe or Cu cations have been commercialized for urea-SCR. One of the most interesting trends in recent years has been the development of small-pore Cu materials. These materials exhibit high hydrothermal stability and high resistance to hydrocarbon poisoning in addition to being highly active and selective for urea-SCR. The commercial breakthrough has also sparked great academic interest in these materials. This paper summarizes the recent development in this field with a couple examples regarding the understanding of how these SCR catalysts operate and also outlines the challenges of developing zeolite catalysts to meet future regulations.

Recent advances and challenges of zeolite catalysts for SCR applications in diesel vehicles

247th National Meeting (2014)

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