Date of Award


Publication Type

Master Thesis

Degree Name



Mechanical, Automotive, and Materials Engineering


Ming Zheng




The impacts of automotive pollutants on local air quality, human health, and climate change are a major concern worldwide. Therefore, the internal combustion engine (ICE) powered automobiles are expected to be able to meet the increasingly stringent emission and fuel efficiency standards. The reduction in oxides of nitrogen (NOx) in lean burn and diesel-fueled compression ignition (CI) engines is a major challenge. In this research, the use of alcohol fuel such as n-butanol and ethanol is studied in a CI engine. With the application of moderate exhaust gas recirculation (EGR), low engine-out NOx and soot emissions are achieved simultaneously. However, to meet NOx emission regulations, the use of only alternative fuels is not sufficient for a wide range of engine operating conditions. Therefore, lean NOx trap (LNT) after-treatment system is used for further NOx reduction using a reductant. In this study, an investigation on the performance of long breathing LNT is performed using ethanol, n-butanol, and diesel as reductants. The LNT regeneration experiments are conducted on a heated flow bench under simulated engine exhaust like conditions. Ethanol and n-butanol are found to be more effective compared to diesel as a reductant in terms of NOx conversion, ammonia (NH3) slip, nitrogen dioxide (N2O) slip, and hydrogen (H2) formation, during the LNT regeneration period at the tested conditions. The formation of NH3 and N2O during the LNT regeneration is not desired. Albeit, the NH3 generated during the LNT regeneration can be utilized to further reduce NOx using a selective catalytic reduction (SCR) convertor downstream of the LNT catalyst. In this study, the combined LNT-SCR tests are performed to investigate overall NOx reduction using n-butanol as a reductant.