(562f) Surface Change of Lean-NOx Trap Adsorbent through CuO Co-Impregnation and Its NOx Storage-Desorption Performance

In major industrial countries, fuel economy regulations have curbed carbon dioxide (CO₂) emissions from vehicles, especially automobiles. In diesel vehicles, the lean-burn engine technology, which is the most popular solution for improving fuel economy, has been used. This technology operates at high air/fuel ratios to make fuel economy efficient while reducing the CO₂ emissions. However, using the lean-burn engine for automobile not only increases NO_x emissions but also reduces the NO_x removal efficiency of conventional catalytic converter. Therefore, the lean-NO_x trap (LNT) has been used to further reduce NO_x emissions from automobiles. In order to develop the vehicles having both low energy and low emission, LNT should be improved in terms of the adsorption performance for NO_x gas at low temperature (the emission condition of a lean-burn engine). In this study, we developed LNT adsorbent in which CuO was co-impregnated with BaO in γ-Al₂O₃ and evaluated its NO_x storage-desorption performance. The characterization of the adsorbents was performed using X-ray diffraction (XRD) and BET surface area was calculated by nitrogen adsorption analysis results. The adsorption capacity of the adsorbents was measured by breakthrough tests using a quartz flow reactor with a NO_x analyzer. The desorption temperature of adsorbed NO_x on the adsorbents was figured out by temperature programmed desorption (TPD) followed by breakthrough tests. Also, the surface change of adsorbents during the NO_x storage-desorption was observed by in-situ FT-IR.