Thermal degradation of microporous Sm2O3–MgO nanocomposites at isothermal conditions and surface chemical properties

The evolution of microstructural, morphological and surface chemical properties of Sm2O3–MgO nanocomposites are determined during and after isothermal heat treatments in the range of 500–1000 °C. The samples are investigated using (high temperature) X-ray diffraction, energy-filtered transmission electron microscopy including electron energy loss spectroscopy, nitrogen adsorption, and temperature programmed desorption of CO2. With small amounts of MgO the initial micropore fractions are low and mainly coarsening of Sm2O3 is observed. Large amounts of MgO result in high initial micropore fractions giving rise to enhanced densification. The different thermal degradation behaviors are explained by means of the respective characteristic diffusion distances which are determined by the volume phase fractions. The surface chemical properties of Sm2O3 and MgO remain qualitatively unchanged, however, the specific CO2 chemisorption capacities are increased through the nanocomposite formation.