Lanthanum-promoted copper-based hydrotalcites derived mixed oxides for NOx adsorption, soot combustion and simultaneous NOx-soot removal

La-promoted Cu-based hydrotalcites derived mixed oxides were prepared and their catalytic activities for NOx adsorption, soot oxidation, and simultaneous NOx-soot removal were investigated. The catalysts were characterized by XRD, DTG, BET, FTIR, H2-TPR, TPD and TPO techniques. The oxides catalysts exhibited mesoporous properties with specific surface area of 45-160 m(2)/g. The incorporation of La and Cu decreased the amount of basic sites due to the large decrease in surface areas. Under O-2 atmosphere, La incorporation is dominant for soot oxidation activity, while Cu favors high selectivity to CO2 formation. A synergetic effect between La and Cu for catalyzed soot oxidation lies in the improved redox property and suitable basicity. The presence of NO in O-2 significantly promoted soot oxidation on the catalysts with the ignition temperature decreased to about 300 degrees C. In O-2/NO atmosphere, NO2 acts as an intermediate which oxidizes soot to CO2 at a lower temperature with itself reduced to NO or N-2, contributing to the high catalytic performance in simultaneous removal of NOx and soot. (C) 2013 Elsevier Ltd. All rights reserved.