In this article, a series of Cu-containing mixed metal oxides were obtained by calcination of layered double hydroxides (LDHs) precursors with Cu/Zn/Al atomic ratios ranging from 1: 3: 1 to 3: 1: 1 in synthesis mixture at 773 K. The materials were characterized by means of powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), nitrogen sorption experiments, and X-ray photoelectron spectroscopy (XPS). The results indicate that Cu/Zn/Al cationic ratios in precursors could control the compositions of surface species on the resultant calcined LDHs. Furthermore, The catalytic activities of phenol oxidation in aqueous solutions by hydrogen peroxide over the calcined LDHs as catalysts were also tested. It is found that the high catalytic activity is relative to the high amount and dispersion of composite metal oxides containing active Cu2+ reaction centers on the surface of calcined samples, and the lattice oxygen species on the surface are beneficial to the deep oxidation of phenol.

Cu/Zn/Fe/Al mixed metal oxides were prepared by calcination of layered double hydroxides (LDHs) carbonate precursors. The iron content had significant influence on the crystallinity, purity and thermal stability of as-synthesized Cu/Zn/Fe/Al-LDHs as well as the structure and composition of resultant mixed oxides obtained at 773K. The mixed oxide with the Fe/Al ratio of 0.3: 0.7 exhibited highest catalytic activity for oxidation of phenol by hydrogen peroxide. Moreover, the Fe-containing mixed oxides had stronger oxidation abilities than the Fe-free ones. The difference of catalytic activity is probably related to the difference in the amounts and types of composite oxides containing Cu2+ and/or Fe3+ cations on the surface of calcined products depending on the pristine nature of the starting LDHs precursors.

Analogous layered double hydroxides (LDHs) with the Cu2+/Ni2+/Cr3+ molar ratio of 1/2/1 on the brucite-like layers and interlayer anions (viz sulfate, nitrate and carbonate, respectively) were synthesized by a coprecipitation method. For the first time, the effects of interlayer anions on the structural properties of as-synthesized LDHs and resulting calcined products at 773K were investigated by means of powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), simultaneous thermogravimetric and differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The results indicate that the nature of interlayer anions involved within the hydrotalcite (HT)-like structure has a larger influence on the thermal stability of LDHs precursors. Calcination of well-crystallized LDHs leads to the formation of mixed metal oxides including CuO, NiO and Cu2+-, Ni2+- and Cr3+-containing spinel phases, the composition distributions of which obtained from LDHs precursors depend on the nature of interlayer anions, thus resulting in the difference of the reducibility of reducible metal species in the calcined LDHs. Moreover, the surface basicity of the calcined material, which is related to the different behaviour of LDHs precursors during the thermal decomposition depending on the interlayer anions, increases progressively following the order of calcined LDHs from sulfate to nitrate and carbonate.

Layered double hydroxides (LDHs) with Cu2+/Zn2+/Al3+ atomic ratios from 1: 1: 1 to 3: 1: 1 have been synthesized by coprecipitation method. The physicochemical properties of both the as-synthesized LDHs and their calcined products obtained at 773K for 3 h have been characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), chemical analysis, transmission electron microscopy (TEM), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS), N2 adsorption–desorption experiments and thermogravimetric analysis (TGA). The chemical states of metal species on the surface of the calcined LDHs were also characterized by temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The results indicate that Cu2+/Zn2+/Al3+ atomic ratio in the synthesis mixtures influences crystallinity, purity, and thermal stability of the LDHs, and hence, the composition of the resulting calcined LDHs. At room temperature and atmospheric pressure, oxidation of aqueous phenol solutions by hydrogen peroxide in the presence of the calcined LDHs was carried out. The results show that the calcined LDHs with the Cu2+/Zn2+/Al3+ atomic ratio of 1: 1: 1 has the highest catalytic activity for conversion of phenol, which may be related to the formation of a great amount of composite metal oxide containing Cu2+ ions and to good dispersion property of active Cu2+ centers present on the surface.

The paper reports data relative to the preparation of a series of manganese-doped copper-based mixed metal oxides under identical conditions by calcination of layered double hydroxides (LDHs) at 773Kfor 5h. LDHs with Cu2+/Zn2+/Mn2+/Fe3+/Al3+ molar ratios in synthesis mixture from 1: 1: 0: 0.3: 0.7 to 1: 0: 1: 0.3: 0.7 have been synthesized by co-precipitation method. The samples of both the as-synthesized LDHs and the corresponding calcined LDHs have been characterized for phase composition by powder X-ray diffraction (XRD), FT-IR spectroscopy and chemical analysis. The calcined LDHs were submitted to X-ray photoelectron spectroscopy (XPS) investigation with the aim of assessing the actual elemental speciation on the surface of the materials from the analysis of the M 2p (M = Cu, Mn, Fe and Al), Cu 3p and O1s spectral regions. Calculating the relative intensities of spectral components to determine the distributions of different chemical states has been performed by the fitting procedure of the experimental XPS peaks, and significant changes were noted when the partial substitution of manganese for zinc is increased.