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International audienceThe process of the decrease of the surface area due to crystallite growth in ceria at 943 K is described by a kinetic model involving oxygen and cerium diffusion. The experimentally found variations in the rate of crystallite growth are reported as a function of the content ( 10% cat.) of dopants, which are the cations Ca²⁺, Mg²⁺, Al³⁺, Y³⁺, Sc³⁺, Al³⁺, Th⁴⁺, Zr⁴⁺ and Si⁴⁺. The variations are discussed on the basis of the diffusion of cerium vacancies as the rate-limiting step, and on the basis of calculated expressions of the concentrations of oxygen vacancies, electrons and cerium vacancies v_s. the oxygen partial pressure and the dopant content. For cations that are smaller than Ce⁴⁺, the comparison between the experimental and theoretical rates asserts the validity of the model and allows the prediction of the efficiency of a cation to stabilize the surface area, from its associations with oxygen vacancies and with the electron-bearing species, Ce′_Ce

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Static atomistic simulation techniques have been employed to identify the low-energy configurations for copper ions within the Cu-ZSM-5 catalyst. We find that both isolated copper and copper clusters form within the zeolite channels, 80% of which are associated with framework aluminum species. A particularly stable and common species comprises two copper ions bridged with extra-framework OH species, which we propose may be a useful model for the active site in Cu-ZSM-5 catalysts.