The Effect of Transition Metal Oxide Dopants on the Structure, Morphology, Surface Texture and Catalytic Properties of FeMgO Nanomaterials Towards Dehydrogenation and Aldol Condensation Reactions

The impregnation method was successfully used to prepare FeMgO and transition metal (Cu²⁺,   Cr³⁺) -doped FeMgO nanomaterials calcined at 500 and 700 ^oC. The as-prepared catalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopic (EDS), specific surface areas (S_BET) and catalytic conversion of 2-propanol at 225-400 ^oC. The results showed presence of MgO spherical nanoparticles as aggregates of uniform trigonal shapes in the catalyst calcined at 500 ^oC. Doping with Cu²⁺ ions modified the morphology to much dispersed spherical iron oxide nanoparticles while doping with Cr³⁺ species increased the agglomeration of the obtained nanoparticles. Doping FeMgO  nanomaterials with Cu²⁺ ions brought about a measurable increase in its S_BET, opposite result was found in case of doping with Cr³⁺ ions. Pure and Cu²⁺-doped nanomaterials act as active dehydrogenation catalysts yielding acetone. CuFeMgO system was highly selective to methyl isobutyl ketone (MIBK). CrFeMgO system was highly selective to propene. The catalytic activity and selectivity of the investigated catalysts depend on both of calcination temperature, reaction temperature, and the nature dopant.