Synthesis of three-dimensionally ordered macroporous Al–Ce mixed oxide catalysts with high catalytic activity and stability for diesel soot combustion

Abstract

A series of three-dimensionally ordered macroporous (3DOM) Al–Ce mixed oxide catalysts were prepared by the colloidal crystal templating method. The obtained catalysts were characterized by means of XRD, SEM, BET, H2-TPR, and Raman spectroscopy. The effects of an Al/Ce ratio on the phase structure and catalytic performances were investigated. Al–Ce mixed oxide catalysts could form solid solutions with moderate aluminum content. 3DOM samples showed higher catalytic activity for soot combustion than corresponding disordered macroporous (DM) ones due to enhanced contact efficiency between the soot and the catalyst. 3DOM mixed oxide catalyst with aluminum to cerium ratio of 3:7 shows the highest catalytic activity for soot combustion, in which the values of T10, T50, and T90 are 297, 384, and 427°C, respectively. The doping of Al into CeO2 catalysts can enhance the catalytic stability of the catalyst. After 6-cycle runs, the T50 value of 3DOM samples with alumina:cerium (3:7) and alumina:cerium (6:4) have no significant change. Furthermore, the effect of thermal treatments on the catalytic properties for soot combustion was also studied. Compared with 3DOM bare CeO2, 3DOM Al–Ce mixed oxide catalysts exhibited higher thermal stability because aluminum can prevent cerium particles from agglomeration.