Impact of the synthesis parameters on the solid state properties and the CO oxidation performance of ceria nanoparticles

Abstract

A direct quantitative correlation of surface-to-bulk (Os/Ob) reducible oxygen of ceria nanoparticles (NPs) with catalytic activity was revealed.

Ceria Catalysts at Nanoscale: How Do Crystal Shapes Shape Catalysis?

“…CO oxidation over nanoshaped ceria particles was investigated by Zhou et al 35 in a study where they compared the light-off performances of nanorods and irregular nanoparticles of similar surface area; the higher activity of the former was attributed to the combination of exposed planes with a higher proportion of {100} and {110} surfaces. This was the first study where the reactivity of nanoshaped particles (NSP) were examined in CO oxidation and it paved the way for several investigations were the correlation between ceria shapes and CO oxidation was clearly established 81,84,107,[126][127][128][129][130][131][132][133] . The light-off activity generally follows the order nanorods>nanocubes> nanoparticles and also the turnover frequency of CO oxidation is higher on {110} followed by {100} and {111} surfaces 126 , which is the reverse order of oxygen vacancy formation energy 54 .…”

Effect of Pr on the electrical and chemical properties of cerium oxide prepared by combustion method

“…The first signal at 505°C corresponds to the reduction of the surface oxygen of Ce 4+ ‐O present on the solid. The second signal, at 829°C, is attributed to the complete reduction of bulk oxygen of cerium oxide with H 2 by the change of state of Ce 4+ ions to Ce 3+ ions, due to the elimination of O 2− anions in the structure . Equation summarizes the previous process.…”

“…Cerium oxide is an attractive material because exhibit single properties, especially the oxygen storage capacity, produced by the reversible redox process (Ce 4+ /Ce 3+ ), which causes structural defects such as oxygen vacancies . The intrinsic properties of CeO 2 could be enhanced by the incorporation of rare earth cations such as praseodymium in the structure, producing oxygen vacancies, which increase when Pr 3+ cations are incorporated, since the energy required for this process is less than the insertion of Pr 4+ .…”

The Effect of CeO2 Preparation Method on the Carbon Pathways in the Dry Reforming of Methane on Ni/CeO2 Studied by Transient Techniques

“…The formation of inactive carbon, in the form of filaments, graphite, and whiskers, mainly is derived from the CH 4 decomposition (CH 4 → C-s + 2H 2 , ∆H 0 = +75 kJ mol −1 ) and Boudouard reaction (2CO → C-s + CO 2 , ∆H 0 = −172 kJ mol −1 ). Thus, the design of a suitable Ni-based catalyst supported on reducible metal oxides emerged (e.g., use of CeO 2 , Zr 4+ -, Pr 3+ -, Ti 4+ -doped CeO 2 , La 2 O 3 , Nb 2 O 5 ) [16][17][18][19][20][21][22][23][24][25] since the latter supports possess oxygen storage capacity (OSC), oxygen vacancies, and high oxygen mobility, leading to carbon gasification rates that significantly reduce carbon accumulation rates, but also provide high thermal stability for the supported Ni catalysts [26,27]. The Ce-based materials owe their advantages against non-reducible metal oxides to the undergoing of fast change in the Ce 4+ ↔ Ce 3+ oxidation state (redox behavior), leading to an oxygen release, and vice versa to an oxygen storage, in the ceria-based stable crystal structure [28,29].…”