Combination of Pt@CeO2/MCM-56 and CeO2-CuO/MCM-56 to purify the exhaust emissions from diesel vehicles

Pt@CeO2/MCM-56 (PCM) and CeO2-CuO (9:1)/MCM-56 (CCM) were combined to purify the exhaust emissions from diesel vehicles in three configuration statuses, defined as configuration A-where CCM stays above PCM, configuration B-where PCM stays above CCM, and configuration C-where CCM mixes with PCM homogeneously in loose contact. Among these combined catalysts, the configuration A is most favorable for the selective catalytic reduction (SCR) reaction, with > 80% NOx conversion obtained at the temperature range of 150-550 degrees C and gas hourly space velocity (GHSV) of 240,000 ml g(-1) h(-1). NH3-TPD, H2-TPR and NH3 conversion measurements demonstrated that NH3 can be selectively used to reduce NOx in the configuration A but is over oxidized if the reaction is operated in configuration B or configuration C status, deteriorating the deNO(x) activity at temperature above 250 degrees C. Hence, configuration A not only takes advantage but also overcomes the shortcomings of PCM and CCM, leading to high NOx conversion and N-2 selectivity. A significant decrease in the onset temperature of soot combustion was also observed in this research.