Nanocomposites for Nitrogen Oxide Emissions Control in Lean-Burn Engines

Over the past few years, increase in environmental concern has led to a demand for more effective pollution control strategies that would satisfy the new EPA standards regarding automotive emissions of nitrogen oxides (NOx). In particular, the removal of NOx from lean-burn and diesel engines operating under an oxygen-rich atmosphere presents a significant challenge as conventional three-way catalysts are ineffective in this environment. Moreover, the presence of water vapor and sulfur oxides (SOx) in the exhaust stream both inhibits catalyst activity and results in long-term catalyst instability. Thus, it is necessary to develop novel technologies for the removal of NOx from the exhaust of lean-bum engines. This thesis examined three metal oxide nanocomposite systems to serve as (i) catalysts for the selective catalytic reduction (SCR) of NOx by propene, (ii) sorbents for SO2 storage, and (iii) catalysts for NOx storage-reduction (NSR). In203-Ga203/A1203 nanocomposite catalysts have been synthesized using th