担载双金属催化剂对Heck反应的作用

制备了0．5％Pd／C催化剂和含钯担载双金属催化剂3％Cu．0．5％Pd／C，3％Mo-0．5％Pd／C，3％Ni-0．5％Pd／C，3％Co-0．5％Pd／C．3％Mn-0．5％Pd／C，用XRD法和XPS法进行了表征。结果表明，室温下，以KBH4还原剂制备的含钯担载双金属催化剂，在碘苯与丙烯酸的Heck偶合反应中，催化活性高于Pd／C（0．5h的转化率高，完成反应所需时问少），显示出添加贱金属的协同效应。其中，3％Mo-0．5％Pd／C显示出最高的催化活性，在0．5h时的转化率（67．4％）和收率（52．6％）比0．5％Pd／C分别高54．5％和42．2％，完成反应的时问最短，表明钼的协同效应最高。

Effect of Supported Bimetallic Catalysts to Heck Reaction

The homogeneous catalysis for Heck reactions has to face the problems of separation and recycle of precious metal-bearing catalysts,which could be possibly solved by using heterogeneous catalysis.There are a lot of reports on the heterogeneous catalytic Heck reactions using palladium and some using non-palladium metals sporadically.The application of supported bimetallic catalysts in this type of reactions is rare although the supported bimetallic catalysts are widely applied to other catalysis.The active carbon supported bimetallic catalysts Mo-Pd/C,Cu-Pd/C,Co-Pd/C,Mn-Pd/C and Ni-Pd/C were prepared by reduction with KBH_4 in solution,respectively,and were characterized by XRD and XPS in our investigation.They show a higher activity in the Heck reaction of phenyl iodide with acrylic acid than that of Pd/C.According to the comparison of the experimental results,the addition of these base metals promotes the catalytic activity of Pd for the Heck reaction obviously and molybdenum shows the highest synergistic effect: the conversion rate and the yield rate are higher than that of Pd/C by 54.5% and 42.2%,respectively.