Direct Recycle Palladium from Spent Automotive Catalyst to Carbon-Supported Palladium

Abstract

In this research, a simple and economical process based on hydrometallurgy is developed to directly recycle platinum group metals from spent automotive catalysts to synthesize carbon supported platinum-group metals catalysts. Spent automotive catalysts are firstly leached by HCl+H2O2 system, resulting in Pd chloro-complexes. The optimized leaching rates of Pd and Rh are 97.99 ± 2.64% and 87.70 ± 1.23%, respectively. Then Pd precursor is separated from the leaching solution by precipitation, which can remove most impurities. The Pd precursor or Pd chloro-complexes solution can be used to synthesize carbon supported catalysts directly via an ethylene glycol reduction method. The samples are characterized by SEM, TEM, XRD, EDS, and ICP-OES. 2–4 nm Pd/C are successfully synthesized using recycled Pd. The recycled Pd/C exhibits excellent long-term stability, with no activity loss in the homemade depolarized electrolyser after 150 h of 100 mA cm−2 electrolysis. The electrochemical tests indicate that the recycled Pd/C samples are not inferior to Pd/C prepared from (NH4)2PdCl4 reagent.