First Stage of Thermal Aging under Oxidizing Conditions of a Ce_0.62Zr_0.38O₂ Mixed Oxide with an Ordered Cationic Sublattice: A Chemical, Nanostructural, and Nanoanalytical Study

Abstract

After being heated in a flow of 5% O2/He, at 1073 or 1123 K for 30 min, a Ce0.62Zr0.38O2 sample showing an ordered cationic sublattice had very subtle surface nanostructural changes induced on it. In parallel with them, a significant loss of low-temperature (T ≤ 773 K) oxygen storage capacity (OSC), with no modification of its high-temperature (T ≥ 973 K) redox response, was observed. These nanostructural and chemical features characterize the very first stage of the process leading to the destruction of the ordered Ce−Zr sublattice, a structural phenomenon playing a key role in the control of redox behavior of ceria−zirconia mixed oxides. The reported results, including OSC, hydrogen chemisorption, and nanostructural and nanoanalytical data, lend further support to a model providing a comprehensive interpretation of the complex relationship linking thermal aging conditions, nanostructural properties, surface chemistry, and redox behavior in these materials.

Focus on the modified CexZr1−xO2 with the rigid benzene-muti-carboxylate ligands and its catalysis in oxidation of NO

“…From the SAED patterns ( Fig. 2(D3 and E3)), the pseudocubic structure could be identified [19,36]. Notably, the (1 1 1) plane was predominate in all samples.…”

3-D flower like Ce–Zr–Cu mixed oxide systems in the CO preferential oxidation (CO-PROX): Effect of catalyst composition

“…It is known that the high performances of CuO-CeO 2 based catalysts are attributable to the strong interaction between highly dispersed copper species and the ceria surface, which favours the formation of oxygen vacancies at the copper-ceria fringes, increasing the Cu reducibility [26][27][28][29][30][31]. The addition of Zr to ceria modifies the redox properties, the oxygen-storage capacity, and thermal resistance of cerium oxide [29,[32][33][34][35][36][37][38]. The efficiency of these three-components catalysts, in comparison with CuO-CeO 2 and CuO-ZrO 2 binary systems, was found to be strongly dependent not only from the molar ratio among reagents but also from the morphological and structural characteristics of the materials that can influence both the interaction between the oxides and the dispersion of the active phase [39][40][41][42][43][44].…”

Stability improvement of ZrO2-doped MnCeOx catalyst in ethanol oxidation

“…MnO x -CeO 2 oxides have been proved to be highly active for the oxidation of light oxygenates [3,4], but they tend to sinter at high temperatures, resulting in severe phase segregation. Doping zirconia to ceria materials have been typically used for promoting the oxygen storage capacity (OSC) and the thermal stability by forming solid solution [5][6][7]. The incorporation of zirconium into ceria lattice alters the local oxygen environment and creates more surface defects, and the formation of homogeneous CeO 2 -ZrO 2 solid solution has greatly enhanced the thermal stability as well [5].…”