Pd(dppm)_2的合成表征及其催化性能研究

Synthesis and Characterization of Pd(dppm)_2 and Its Catalytic Properties

合成了以双齿膦dppm为配体的金属配合物Pd(dppm)2,通过元素分析、红外光谱、热分析、光电子能谱、多晶粉末衍射等技术对该配合物的结构进行表征;用该配合物制备负载型Pd催化剂,并对其催化性能进行了研究,表明该催化剂对CO催化氧化成CO2的反应具有较好的催化效果.

The title complex,Pd(dppm)_2 was prepared by treatment of a solution of PdCl_2 with bis(diphenylphosphino)methane (dppm) and NH_2NH_2·H_2O in nitrogen atmosphere,with yield at 81.2 percent.As a new palladium complex with ligand of phosphine,Pd(dppm)_2 was characterized by elementary analysis,IR spectra,XPS spectra,X-ray powder analysis,as well as thermal analysis.A plane square structure of the complex was supposed.The IR and XPS measurements showed that the state of Pd in the complex of Pd(dppm)_2 was in between zero- and +2 state,and Ph-P-Pd-P-Ph hyperconjugation was found in the complex.Pd(dppm)_2/γ-Al_2O_3 catalyst was prepared by solvated metal atom impregnation (SMAI) method.The result of activity assay indicated that the catalyst of Pd(dppm)_2 supported onγ-Al_2O_3 with high dispersion showed high catalytic activity for the oxidation of carbonmonoxide,with CO conversion reaching 100% at 75℃ and GHSV=30 000 mL(STP)·h^(-1)·g^(-1),with good stability during 19 h of reaction operation.The Ph-P-Pd-P-Ph hyperconjugation enlarge the dislocalization scope of the electron cloud,which may be an important reason that Pd(dppm)_2/γ-Al_2O_3 catalyst exhibited higher activity for CO oxidation at low temperature than that of PdCl_2/γ-Al_2O_3 catalyst at the same experimental condition.