Efficiently multifunctional catalysts of 3D ordered meso-macroporous Ce0.3Zr0.7O2-supported PdAu@CeO2 core-shell nanoparticles for soot oxidation: Synergetic effect of Pd-Au-CeO2 ternary components

摘要

Efficiently multifunctional catalyst of PdAu@CeO2 core-shell nanoparticles supported on 3D ordered meso-macroporous Ce0.3Zr0.7O2 (PdAu@CeO2/3DOMM-CZ) was elaborately synthesized by gas bubbling-assisted membrane reduction-precipitation (GBMR/P) method. The uniform 3DOMM structure with the larger surface area improves the contact efficiency between reactants (O-2, NO and soot) and catalysts, and increases the density of supported active sites. The nanostructure of AuPd (core) and CeO2 layer (shell) with optimal interface area of metal-oxides increases the surface density of active oxygen species (oxygen vacancy) for enhancing adsorption and activation of O-2 and NO reactants. PdAu@CeO2/3DOMM-CZ catalyst, which takes both advantages of the good contact efficiency between reactants and catalysts by 3DOMM structure and the high density of active sites for activated reactants (O-2 and NO) by PdAu@CeO2 core-shell NPs, exhibited super catalytic performance for soot oxidation under conditions of the simulated real exhaust including NO, soot, N-2, O-2 and H2O. For instance, its TOF value is 2.51 h(-1) at 290 degrees C, which is more than 5-fold increase for 3DOMM-CZ oxide (0.46 h(-1), and the values of T-10, T-50, T-90 are 276, 363, 404 degrees C, respectively. PdAu@CeO2/3DOMM-CZ catalyst exhibits the high stability and the good tolerance property for SO2 during catalytic soot oxidation. The catalytic mechanism for soot oxidation was investigated by in-situ Raman spectra, and the synergetic effect of Pd-Au-CeO2 ternary active components can promote the rate determining step of NO oxidation to NO2. Insight into the fabrication strategy and the catalytic mechanism for soot oxidation are expected to further obtain the high-efficient catalyst in the practical applications.