Recuperação de metais do grupo da platina a partir de catalisadores automotivos desativados

Abstract

The platinum group metals (PGM) are largely applied in several industrial cantles, mainly in the fields of electronical components, electrodepositions, catalysts and fine chemistry. However, they are materials that are not so available, even in their main reservoirs. Joining this scarcity to the high demand, we have very expensive elements and natural reservoirs that tend to rarefaction. PGM based catalyst, like the automotive ones, are equipment that preserves the platinum (Pt), palladium (Pd) and/or rhodium (Rh) loads on their structure, even after closing their life-cycles. It makes from the automotive catalysts a huge secondary source of this metals, that can be explored. So, the recycling of the catalysts for recovering the PMG could reduce the cost of this metals, besides save the natural reservoirs and avoid the environmental impacts resulting of its exploration. It’s already an accomplished process, and some technics are fully developed. In this work, it was proposed a hydrometallurgical method for the recovery of the PGM, which is a technic of dissolving the metals in acid solution. From the dissolutions, MEV/EDS, UV-Vis spectroscopy, and electrochemical deposition analysis were taken to verify the presence of the interest metals. The analysis showed that the catalysts used before the legal requirement did not contain PGM in its composition, once it was not found any signal of the PGM in the solution resulting from the processing of the sample obtained from a vehicle made in 1998. On the other hand, the analysis on the sample from a vehicle manufactured after the law requirement showed positive results for the presence of PGM. While the UV-Vis spectra obtained by the scanning of the sample between 190nm e 800nm have coincided with the scanning of the standard on the same window, the voltammograms obtained by the electrochemical analysis showed signals of deposition and oxidation of Hupd, that relate to the Pt presence. Therefore, the high activity of the surface for the hydrogen release reaction after the deposition indicates the presence of PGM. Still, from the observations, the concentration of PGM on the final solution represented a recovery of 1,35g of PGM per kg of catalyst, what means it was satisfactory for the recovery of the interest metals.