(575at) The Effects of Preparation Methods for Pd/Al2O3 and Pd/TiO2/Al2O3 Catalysts on the Denox Activity Under Simulated Post Euro-4 Exhaust Condition

As exhaust gas regulation is stricter, most of mobile companies try to develop the efficient and friendly-environmental mobile. In case of gasoline engine, as three-way catalyst system is utilized, pollutant gases dramatically decreased. But diesel engine has its limits of exhaust gas pre-treatment such as fuel supply system, optimization of fuel tank shape and EGR (Exhaust Gas Recirculation). Therefore, removal techniques of nitrogen oxides and PMs (Particulate Matter) emitted from diesel engine occupied the attention of the entire world. DeNOx (decomposition of NOx) system is classified into Active and Passive Lean NOx systems. Among the Active Lean NOx system, selective catalytic reduction (SCR) is generally studied using reductants such as urea, hydrocarbon (olefin, paraffin), and ion-exchanged ZSM5 catalysts. However active system is complicated because that system needs further equipment for adding the reducing agents. To solve this problem, Passive system which needs no apparatus for reducing the exhaust gas is watched with keen interest. Passive system can remove the NOx gases using available reductant gas (i.e. carbon monoxide) in exhaust gas.

Palladium catalysts are remarkable owing to their potential for controlling NOx emissions and because they are less expensive and more abundant than other noble metals. Therefore, in this study, palladium catalysts supported on ¦Ã-Al2O3 and TiO2/Al2O3 supports were applied to NO + CO reaction(NOx/CO ≥ 16) in the presence of excess oxygen and water under the simulated Post Euro-IV exhaust condition. Especially we studied the effect of preparation methods for the palladium supported catalysts on the DeNOx activity and carried out characterization test such as XRD, XPS and CO chemisorption to acquire the properties of these catalysts.