Degradation of VOCs and NOx over Mg(Cu)-AlFe mixed oxides derived from hydrotalcite-like compounds

Abstract

A series of Mg(Cu)-AlFe mixed oxides derived from hydrotalcite-like compounds has been prepared. These solids were characterized by various physicochemical methods and their catalytic performances were tested towards the catalytic oxidation of propene and the simultaneous elimination of propene and NOx. X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the formation of the hydrotalcite structure for all the solids, except for Cu4AlFe HT, for which a mixture of the hydrotalcite and the malachite phases is observed. The XRD study of the calcined samples revealed the existence of metal oxides and spinels of types MgO, CuO, γ-Fe2O3 or/and Fe3O4, MgFe2O4 and CuFe2O4. During propene oxidation, it was shown that the increase in the copper content enhanced the activity of the solids. However, Cu2Mg2AlFe 500, with the highest amount of surface copper species, exhibited the best activity towards the simultaneous elimination of propene and NO. Indeed surface Cu species are the active sites, while bulk Cu species could provide the adsorption sites for nitrogen species. © 2014 Académie des sciences. Published by Elsevier Masson SAS.