The MMOs used in the present study were obtained by calcination of the corresponding LDH, which in turn were synthesized by the co-precipitation technique and microwave-hydrothermal crystallization. The structures of the DLHs were confirmed by X-ray diffraction. Figure shows the diffractograms for LDH M 2+ /M 3+ (Mg 2+ , Co 2+ , Ni 2+ , Zn 2+ , Fe 2+ , Al 3+ and Cr 3+ ), in which LDH exhibited M 2+ /M 3+ reflections associated with the layered double hydroxide crystal structure. Planes can be observed at (0 0 3), (0 0 6), (0 and). These values are the same as those described in the literature for these materials. Then, the LDH was calcined at 550 °C for 6 hours, and the respective MMOs with a periclase-like structure were obtained. The plane reflections observed in the diffractograms at and) are typical of MMOs (Fig. ). 24 The adsorption of N2 (the BET method) was used to quantify the surface area and pore size of the materials (Table ). The LDH samples exhibited lower porosity and a greater surface area than did the MMO samples.