Fabrication of Spinel-Type PdxCo3–xO4 Binary Active Sites on 3D Ordered Meso-macroporous Ce-Zr-O2 with Enhanced Activity for Catalytic Soot Oxidation

3D ordered meso-macroporous (3DOMM) Ce 0.2 Zr 0.8 O 2 (CZO) was successfully synthesized by a combined method of evaporation-induced interfacial self-assembly (EISA) and colloidal crystal templates (CCT). The multifunctional catalysts of spinel-type Pd x Co 3– x O 4 nanoparticles (NPs) supported on 3DOMM CZO were fabricated by a gas bubbling assisted coprecipitation (GBCP) method. The relationship between nanostructure (hierarchical pore and spinel-type active phase) and activity during catalytic soot oxidation was studied by the techniques of SEM, TEM, XPS, H 2 -TPR, NO oxidation, soot-TPO, and so on. The 3DOMM structure with a larger surface area and total pore volume increases the amount of supported active sites and enhances the contact efficiency between reactants (soot, O 2, and NO) and catalysts. Spinel-type Pd x Co 3– x O 4 (AB 2 O 4 ) binary active sites by substitution for Co 2+ (A site) with Pd 2+ cations are beneficial for improving activation efficiency for gaseous reactants (NO and O 2 ). The novel nanocatalysts of 3DOMM CZO-supported spinel-type Pd x Co 3– x O 4 NPs exhibited superb catalytic performance and strong nanostructure-dependent activity for soot oxidation under loose contact of soot with catalyst. For instance, the T 10, T 50, and T 90 values of 3DOMM PdCo 2 O 4 /CZO catalyst with the highest catalytic activity (TOF = 2.56 h –1 ) are only 313, 367, and 404 °C, respectively. The NO 2 -assisted catalytic mechanism for soot oxidation is studied and proposed by in situ Raman spectra, and the role of spinel-type PdCo 2 O 4 binary active sites is revealed. 3DOMM Pd x Co 3– x O 4 /CZO catalysts are decent systems for soot oxidation, and the easy preparation technology has the potential for application to catalysts with other element compositions.