Morphological and structural differences of Fe-Zn-Al oxide nanocomposites obtained from citrate decomposition and microemulsion method

Ternary Fe-Zn-Al oxide nanostructured material was either co-precipitated in water-in-oil microemulsion or prepared by citrate method. After calcination, the structural features of both samples were studied by XRD, N2 physisorption, SEM, TEM, TPR-H2 and their catalytic behavior in CO2 hydrogenation was determined. The sample obtained from the citrate method consists of Fe2O3 and a Fe-containing spinel phase. The mixed oxide synthesized by the microemulsion method consists of pure iron oxide in Fe3O4 inverse spinel structure epitaxially grown on a Fe-Zn-Al oxide parent structure. Compared to the sample obtained by the citrate method, the structural features of the composite from the microemulsion method are of potential interest for catalytic applications or for transfer to other multinary systems due to the presence of epitaxy. •Fe-Zn-Al nanocomposite were prepared with microemulsion and citrate methods.•Preparation route affects the crystallographic structure and morphology of materials.•Microemulsion method generates more homogeneous particle morphology.•In microemulsion sample pure Fe3O4 regions and a FeZnAl inverse spinel phase form.•In citrate-derived sample, Zn-Al-O spinel and separate Fe2O3 (hematite) are present.