MgO powders: interplay between adsorbed species and localisation of basic sites

MgO powders have been prepared from different precursor compounds and calcined at temperatures in the range 873-1253 K. Sequences of basic strength of the powders have been obtained, in benzene, by the Hammett-Bertolacini method, as a function of the preparation conditions, ageing and reactivating treatments. All the samples have been submitted to XPS (X-ray photoelectron spectroscopy) determinations to assess their actual chemical state. Data relative to the binding energy of the C-1s and O-1s peak components are elaborated and cross-compared with the outcome of the acid-base characterisations also in the light of TPD (temperature-programmed desorption) determinations. The factors affecting the surface reactivity and the localisation of the basic sites, at the different temperatures, are discussed. (C) 1998 Elsevier Science B.V.