Facile synthesis of 3D ordered macro-mesoporous Ce1-xZrxO2 catalysts with enhanced catalytic activity for soot oxidation

A series of three-dimensionally ordered macroporous-mesoporous (3DOM-m) ceria-zirconia oxide (Ce1-xZrxO2) catalysts were synthesized successfully by combined methods of the evaporation-induced interfacial self-assembly and colloidal crystal templates (EISA-CCT). The hierarchical porous nanostructure of 3DOM-m Ce1-xZrxO2 catalysts possess the highly ordered macroporous framework with the average pore size of 250 nm; and the plenty of ordered mesopores (5 nm) are dispersed on the inner walls of spherical macropores. 3DOM-m Ce1-xZrxO2 catalysts with abundant oxygen vacancies have the excellent storage oxygen capacity, which is benefit for improving the catalytic activity for soot oxidation. Ordered macroporous framework enhances the contact efficiency between solid soot particles and catalysts, while the ordered mesoporous nanostructure improves the specific surface area dramatically for promoting the contact efficiency of gaseous reactants (O-2 and NO) and active sites. The enrichment of Ce component as active sites was observed on the inner wall of ordered mesopores formed by the Kirkendall effect during thermal treatment, which can improve the adsorption-activation ability for gaseous reactants. 3DOM-m Ce1-xZrxO2 catalysts with hierarchical porous nanostructure exhibit high catalytic activity and stability for soot oxidation. The facile fabrication strategy of 3DOM-m catalysts can be extended to other oxides. And insight into the catalytic activity dependence on the both elemental composition and porous nanostructure is not only meaningful for development of advanced catalysts for soot oxidation, but also supports the development of 3DOM-m catalysts for practical applications.