Boosting soot combustion efficiencies over CuO–CeO2 catalysts with a 3DOM structure

Abstract

Three-dimensionally ordered macroporous CuO–CeO₂ catalysts were successfully synthesized by the colloidal crystal template route and systematically characterized by means of XRD, FESEM, HRTEM, BET, XPS, FTIR, H₂-TPR and O₂-TPD. The 3DOM CeO₂ with a CuO loading amount of 9.7 wt% exhibited the optimal catalytic activity, giving a T_m of 427 °C and an exceptionally high CO₂ selectivity of nearly 100%. This superior activity was attributed to the enlarged contact area between the catalyst and soot particles, the improved mass transfer caused by the well-defined 3DOM structure and the enhanced redox capability at low temperatures mainly associated with the highly dispersed copper species. Meanwhile, the effect of feed compositions on soot combustion efficiencies revealed that NO and H₂O had a crucial promoting effect on the catalytic oxidation of soot particles because NO₂ formed via in situ NO oxidation during the reaction and H₂O significantly reduced the activation energy of carbon. Furthermore, this catalyst also demonstrated strong durability against structural collapse owing to the well-defined and robust 3DOM structure, indicating its potential applications under practical working conditions.