Characterization and catalytic activity of lead-promoted palladium nanoparticle catalysts

A Pd–Pb/C bimetallic catalyst was prepared by the method of chemical reduction impregnation. Transmission electron microscope studies showed that metal particles were dispersed well and their size was around 10 nm, which was consistent with the calculation result of Scherrer equation and X-ray diffraction patterns. The X-ray photoelectron spectroscopy measurements were performed to illustrate the valence state of palladium and lead in the catalysts and the electron effect between these two metals. We tested the catalytic activity of 5% Pd–1% Pb/C catalyst, which exhibited higher catalytic activity than that of 5% Pd/C in the oxidation of polyethylene glycol dodecyl ether to corresponding carboxylic acid, indicating that a synergetic effect existed between Pb and Pd. A possible mechanism of aerobic oxidation was proposed based on the fact of electron transfer between Pd and Pb. Water was used as solvent and oxygen as oxidant makes the reaction interesting from both economic and environmental point of view.