Preparation、Characterization And Catalytic Performance Of Cu-Mg-Al Hydrotalcite Like Compounds And Their Composite Oxides Catalysts

The development and application of catalyst with high activity and high selectivity is one of the key problems in catalysis. Cu-Mg-Al hydrotalcite like compounds (HLC) were prepared by different methods. Furthermore, their respective Cu-Mg-Al composite oxides were obtained by calcination of HLC. All these samples are applied to the coupling reaction to evaluate the catalytic activity.Firstly, Cu-Mg-Al hydrotalcite like compounds with different Cu-Mg-Al molar ratios were synthesized by urea hydrolysis-hydrothermal synthetic methods. The catalyst performance for the synthesis of diphenyl ether reaction from iodobenzene and phenol was investigated.Secondly, double drop-coprecipitation method was used to prepare the Cu-Mg-Al hydrotalcite like compounds. The influence of the preparation conditions on the crystal phase of catalyst and the catalytic performance was investigated. The synthesized compounds were characterized by X-ray diffraction (XRD)、hydrogen temperature-programmed reduction (H2-TPR)、infrared spectroscopy (IR) and scanning electron microscopy (SEM). The influences of the preparation methods on physical and chemical properties of Cu-Mg-Al catalysts and its catalytic behavior were studied. The results showed that the catalyst derived from double drop-coprecipitation with Cu/Mg ratio of2gave the highest activity and the product of diphenyl ether yield reached above99%.Finally, Cu-Mg-Al composite oxide catalyst was obtained by calcination the Cu-Mg-Al hydrotalcite like compound precursor. The activity of catalyst for synthesis of1-phenyl imidazole reaction with iodobenzene and imidazole was investigated. The effects of calcination temperature and calcination time on crystallinity, catalyst particle size, specific surface area, redox properties and catalytic performance were studied.