Preparation Of Supported Palladium Catalysts And Catalysis Of Suzuki Coupling Reactions

Three kinds of palladium catalysts without ligand for the heterogeneous Suzuki reaction were prepared by using hydrotalcite as the supporter. The structure and composition of the above-prepared.catalysts were characterized by FT-IR, TQ XRD, XPS,TEM and ICP-AES.The palladium catalysts supported on surfactant intercalated hydrotalcite were synthesdized via precipitation-hydrothermal method, MgAl-LDH-DS-Pd,and CaAl-LDH-DS-Pd. The content and dispersion of palladium on catalysts were 1.752 x 10-4 mol/g and 13.65%. CH3CH2OH/H2O were used as the solvent and KOH were used as the base.The product yield of MgAl-LDH-DS-Pd can reach to 95.26% by using 3.5�10-3mmol Pd within 60 min at 60? for the Suzuki coupling reaction. In the same conditions, the product yield of CaAl-LDH-DS-Pd can reach to 96.41% by using 3.2�10-3 mmol Pd.Both the product yield of the third recycled reaction can get more than 95%Magnetic hydrotalcite has been prepared by chemical co-precipitation method. Then the magnetic catalyst was synthesdized by impregnation method of load, namely magnetic-LDH-Pd. The result of characterization demonstrated that the palladium content of the sample is 1.896�104 mol/g. The palladium dispersion measured by chemisorption were 19.26%. Ethanol /H2O and K2CO3 were used as the solvent and base, the third recycled reaction can get more than 90%. Products yield by using 3.80�10-3 mmol Pd within 80 min at 70? for the Suzuki coupling reaction.