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The rapid loss of performance of lean NOx traps is well-known and has been attributed to precious metal sintering, based on the analysis of catalysts aged on bench-top reactors, on dynamometers, and on vehicles. This precious metal sintering leads to reduction in surface area contact between the precious metals and NOx adsorbers. As a result, the catalyst sites available for NOx oxidation and the adsorber sites available for NO2 adsorption are drastically reduced. The use of bench-top reactors, dynos and vehicles to provide aged catalyst samples for analysis is tedious and time consuming. In order to rapidly screen catalysts for microstructural changes, we have designed an ex-situ reactor that allows us to expose catalyst samples on a TEM grid to operating conditions using a simulated exhaust.

Greenhouse gas regulations and global economic growth are expected to drive a future demand shift towards diesel fuel in the transportation sector. This may create a market opportunity for cost-effective fuels in the light distillate range if they can be burned as efficiently and cleanly as diesel fuel. In this study, the emission performance of a low cetane number, low research octane number naphtha (CN 34, RON 56) was examined on a production 6-cylinder heavy-duty on-highway truck engine and aftertreatment system. Using only production hardware, both the engine-out and tailpipe emissions were examined during the heavy-duty emission testing cycles using naphtha and ultra-low-sulfur diesel (ULSD) fuels. Without any modifications to the hardware and software, the tailpipe emissions were comparable when using either naphtha or ULSD on the heavy duty test cycles.

New regulations requiring increases in vehicle fuel economy are challenging automotive manufacturers to identify fuel-efficient engines for future vehicles. Lean gasoline direct injection (GDI) engines offer significant increases in fuel efficiency over the more common stoichiometric GDI engines already in the marketplace. However, particulate matter (PM) emissions from lean GDI engines, particularly during stratified combustion modes, are problematic for lean GDI technology to meet U.S. Environmental Protection Agency Tier 3 and other future emission regulations. As such, the control of lean GDI PM with wall-flow filters, referred to as gasoline particulate filter (GPF) technology, is of interest. Since lean GDI PM chemistry and morphology differ from diesel PM (where more filtration experience exists), the functionality of GPFs needs to be studied to determine the operating conditions suitable for efficient PM removal.