New binary systems Mg– M–O ( M=Y, La, Ce): Synthesis and physico-chemical characterization

Abstract

New binary oxide Mg– M–O ( M=Y, La, Ce) systems are obtained by co-precipitation and characterized by adsorption methods, X-ray diffraction method (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy of adsorbed probe molecules (CO and CDCl 3). It is shown that Mg–Y–O systems after calcination at 450–750 °C represent the physical mixtures of MgO and Y 2O 3, while the components of Mg–La(Ce)–O systems interact to form La 2MgO x and (Ce,Mg)O 2 solid solutions, respectively. From XPS data, the surface of the binary systems is enriched with lanthanide ions. Addition of ≈5 mol% M 2O 3 to MgO results in an increase in concentrations of strong and weak Lewis acidic sites, the content of the latter being much higher and changing in the series: MgO<Mg–Ce–O<Mg–La–O<Mg–Y–O. At the same time basic sites become stronger in the binary systems but their total content decreases in comparison to that in individual MgO. Mg– M–O samples containing ≈5 mol% M 2O 3 are highly-dispersed and characterized by bimodal porous texture.