MgZnAl hydrotalcite-like compounds preparation by a green method: effect of zinc content

Abstract

A series of MgZnAl hydrotalcite-like compounds with different zinc content (1–25 mass % of nominal zinc content) were prepared by a simple and environmentally-friendly method. The solids were characterized by X-ray powder diffraction (XRD), thermogravimetric (TG), nitrogen adsorption-desorption at −196°C (BET), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and CO2 temperature-programmed desorption (CO2-TPD). Transesterification of castor oil with methanol was selected as a probe reaction to stress the effect of zinc incorporation. From the XRD analysis of fresh samples it was demonstrated that the incorporation of zinc is feasible in the nominal range of 1–10 mass % while in the samples with higher zinc content, zinc nitrate and ZnO as secondary crystalline phases were observed. Furthermore, the analysis of samples calcined at 450°C indicated the coexistence of the ZnO and MgO crystalline phases. From the EDS and TG characterizations, the zinc percentage and thermal decomposition of the samples were determined. It was revealed that the samples exhibited the characteristic platy-like habit of hydrotalcite-like compounds. The BET analysis confirmed that the calcined samples presented an increment in their specific surface area values compared with the pristine ones. It was established that the amount of basic sites diminished with the zinc incorporation, which also affected the conversion degree of the transesterification reaction.

Tuning the acidic–basic properties by Zn-substitution in Mg–Al hydrotalcites as optimal catalysts for the aldol condensation reaction

“…molar ratio). Similar results were observed by Sánchez-Cantú et al [29] during the synthesis of Mg-Zn-Al hydrotalcites. According to these authors, an increment in the concentration of Zn 2?…”

“…Observing the NH 3 -TPD profiles presented in Fig. 6, it [29,37,38]. This trend is in a good agreement with the observations described before from the CO 2 -TPD analysis, where it was concluded that the introduction of Zn 2?…”

Enhanced photocatalytic activity of TiO2-impregnated with MgZnAl mixed oxides obtained from layered double hydroxides for phenol degradation

“…Less Mg in the hydrotalcite structure could lead to a smaller surface area, pore volume and an irregular distribution of the zinc as observed in this study (Table 1) and evidenced by Valente et al [29], Alanis et al [17] and Sánchez-Cantú et al [53].…”

X-ray Diffraction Analysis on Post Treatment of Ca-Mg-Al-Layered Double Hydroxide Slurry

“…Cooling time with stirring could make a collision particle one another particle perfectly, but very longer stirring could make crystal structure broken or collapse. Lattice parameter a refers distance of octahedral O-O in layer and lattice parameter c is the distance of interlayer [25]. This showed that HT-1 experience decreasing distance interlayer due to uneven distribution in balancing anion with the commercial Mg-LDH as the standard of comparison.…”