Diesel Emission Control in Review

This summary covers the developments from 2006 in diesel regulations, engine combustion, and NOx and PM remediation. Regulatory developments are now focused on Europe, where light-duty Euro 5 and 6 regulations have been proposed for 2009 and 2014, respectively. The regulations are lass stringent than those in the US, but options exist for adopting European vehicles for the US market. Europe is just beginning to look at heavy-duty regulations for 2012 and beyond. Engines are making very impressive progress, with clean combustion strategies in active development mainly for US light-duty application. Heavy-duty research engines are more focused on traditional approaches, and will provide numerous engine/aftertreatment options for hitting the tight US 2010 regulations. NOx control is focusing on SCR (selective catalytic reduction) for diverse applications. Focus is on cold operation, durability, secondary emissions, and system optimization. Aged LNTs (lean NOx traps) are effective up to about 60-70% deNOx efficiency, and are being considered for light-duty and some light heavy-duty applications. There is growing interest in supplementing LNT performance with integrated SCR, which utilizes ammonia generated in the LNT during rich regenerations. Diesel particulate filter technology is in a state of optimization and cost reduction. Very sophisticated management strategies are being utilized, which open up options for new filter materials and alternative system architectures. Secondary emissions issues are emerging and are being addressed.