Executive Summary : | Objective: Leaching of spent PGM catalysts through chlorination utilising exhaust gas from electroplating processes; Understanding the leaching pathways, kinetics and efficiency. Conversion of dissolved metal salts in to solid metal precursors; selectivity of anodic reaction to chlorine and oxygen evolution and its effect on the extent of PGM dissolution Summary: Recovery of PGMs from spent catalysts will be performed using an environmentally friendly approach. Chlorine has been used to leach metals due to its positive electrode potential. However, it has to be generated externally for this purpose. Many industrial electrochemical processes such as electroplating, molten salt electrolysis involve chloride based baths which release hazardous chlorine gas. The exhaust can be used as a leachant and complexant of noble metals. Moreover, chlorine along with oxygen evolves from anode at the typical current density (0.1 to 0.5 A/cm2) employed for plating processes. So, PGM dissolution will depend on the faradaic efficiency of the chlorine evolution. Also, the presence of oxygen could impact the dissolution kinetics. Hence, in this study, we explore the possibility of utilizing chlorine, a byproduct of electroplating processes, to dissolute PGMs and recover them as chloride complexes in solid form and as reactivated nanoparticle catalyst on carbon support by reducing the as-dissolved complexes chemically. |
