Superior catalytic performance of a CoOx/Sn–CeO2 hybrid material for catalytic diesel soot oxidation

Abstract

The present work reports the synthesis and characterization of a ceria-based hybrid nano-catalyst composed of a Sn^x+ dopant incorporated in the CeO₂ crystal lattice and a finely dispersed CoO_x phase on its surface. Characterization studies showed that the Ce, Sn, and Co cations were present in their multivalent oxidation states. The CoO_x was confirmed to be Co₃O₄. A HRTEM image depicted the presence of a stepped catalyst surface, which has a special importance in enhancing the heterogeneous catalytic reaction rate carried out on the solid catalyst surface. The prepared materials were subjected to diesel soot oxidation catalysis. Model soot was combusted in the presence of air under both tight and loose contact conditions of the catalyst and soot. The hybrid catalyst exhibited improved performance compared to the Sn-doped nano-CeO₂ and nano-CeO₂ supported CoO_x catalysts. The improved catalytic activity was attributed to the existence of synergism among the multivalent cations and the stepped surface of the hybrid catalyst, which act as the potential active sites for oxidation catalysis.