Preparation Characterization And Catalytic Performance Of Cu-Hydrotalcite Like Compounds

Hydrotalcite-like compounds are a class of layered double hydrotalcites (LDHs), which is a group substance of anion exchange in inter layer, cation modulation capacity of brucite layer. The unique layered structure and properties of hydrotalcites make them in catalyst have a wide range of applications. Hydrotalcite like compounds and its composite oxide catalysts are widely used in numerous organic synthesis because of the virtue of their properties such as catalystic performance and recyclability. Furthermore, LDHs catalysts with highly effective, easy separation, environmental friendly and stability are receiving significant attention. C-N coupling and oxidative esterification of aldehydes are both important C-X bond-forming reactions, especially in catalysis field. In this thesis, a series of composite oxides catalysts derived from LDHs were prepared and the catalytic performance for C-N coupling reaction of imidazole with aryliodide was investigated. Furthermore, the catalysts CuMgAl-LDH were prepared and their catalytic performance for oxidative esterification of aldehydes was discussed.Firstly, a series of catalysts with various Cu/Zn/Al molar ratios were prepared by decomposition of CuZnAl hydrotalcite precursors at 600? for 3 h. The catalysts were characterized by XRD, N2 adsorption-desorption (BET), AAS, H2-TPR TG-DTA and XPS. The effect of the ratio of Cu/Zn/Al on the performance for C-N coupling reaction of imidazole with aryliodide was investigated. The results revealed that CuZnAl molar ratio of 2:1:1 had the best activity, and we discovered that the product of 1-phenylimidazole was obtained in good to excellent yield by using KOH as base at 130? under air atmosphere.Secondly, CuZnMgAl composite oxide catalyst was obtained by calcination the CuZnMgAl hydrotalcite precursor. The catalyst was characterized by XRD, N2 adsorption-desorption (BET), H2-TPR and TG-DTA. The catalytic performance for synthesis of 1-phenylimidazole reaction with imidazole and aryliodide was investigated.Finally, coprecipitation method was utilized for the preparation of CuMgAl hydrotalcite like compounds. XRD, N2 adsorption-desorption, H2-TPR, XPS and AAS were used to characterize the catalysts. The catalytic performance for oxidative esterification reaction of aldehydes with alkylbenzenes was investigated. The results showed that Cu2MgiAl1-LDH was the optimal catalyst, with the 81.0% benzyl benzoate yield. The catalytic performance of CuMgAl hydrotalcite like compounds for oxidative esterification of aldehydes was discussed for the first time.