ELECTROCHEMICAL STUDY OF SOME PALLADIUM COMPOUNDS AT A CARBON PASTE ELECTRODE APPLICATION TO THE DETERMINATION OF PALLADIUM IN OXIDATION AUTOMOTIVE CATALYSTS

The carbon paste electrode has been used for studying the electrochemical behaviour of Pd(II), Pd(0) and palladium black. Some of our results are consistent with the already existing literature values except the reduction of PdO into Pd metal which was found to occur at about -20 mV/sce in 0.5 M HClO4. The freshly deposited palladium metal was relatively easier to oxidize compared with the commercial one. We have also applied this method to the quantitative determination of palladium in oxidation automotive catalysts. Palladium was present in the form of Pd(0) in the new catalyst examined, while a substantial fraction of it was converted into PdO in the corresponding spent catalyst.