M(II)-Al-Fe layered double hydroxides synthesized from aluminum saline slag wastes and catalytic performance on cyclooctene oxidation

Abstract

• M(II)AlFe-LDH were prepared from aluminum saline slags by a co-precipitation method. • LDH synthesized from slags were used as catalysts for the cyclooctene oxidation. • M(II)AlFe-LDH derived from aluminum saline slags were efficient oxidation catalysts. Aluminum was extracted from saline slags via an alkaline method and employed in the synthesis of Layered Double Hydroxides (LDH) with various M 2+ cations (Co, Mg, Ni and Zn), while Al and Fe were the M 3+ cations, using the co-precipitation method and a M 2+ /M 3+ 2:1 ratio. The structural characterization of the samples was performed with powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), nitrogen physisorption at 77 K, thermogravimetric analysis (TGA), temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). Their catalytic performance was tested for the oxidation of olefins (cyclooctene) and their biomimetic potential was analyzed. Results show a great selectivity towards epoxides with no other products obtained. Reaction yields followed the descending order Co 4 AlFe, Zn 4 AlFe, Ni 4 AlFe, and Mg 4 AlFe, the sample with cobalt as M 2+ converting up to 85% of cyclooctene.