Catalytic performance of supported Ag nano-particles prepared by liquid phase chemical reduction for soot oxidation

摘要

The effect of size and morphology of Ag catalysts supported on ZrO2 on the soot oxidation activity was investigated. Spherically shaped Ag nano-particles with the size of ca. 16 nm, prepared by liquid-phase chemical reduction, supported on ZrO2 (Ag/ZrO2(NP)) exhibited outstanding performance for soot oxidation with gaseous O-2 in tight and loose contact modes, compared with hemispherically shaped Ag particles prepared by impregnation (Ag/ZrO2(IMP)). The exceptional performance of Ag/ZrO2(NP) for soot oxidation in loose contact mode was explained by relatively good catalyst-soot contact state and effective migration of active oxygen species from the catalyst to soot. In addition to morphological effect, Ag nano-particles supported on ZrO2 were found to be stabilized in the surface valence state of Ag+, and then oxygen species participating in soot oxidation can be effectively activated on Ag+ sites. We concluded that the presence of Ag+ sites on the surface of Ag nano-particles is responsible for high soot oxidation activity. (C) 2014 Elsevier B.V. All rights reserved.