(2hg) Rhodium and Platinum Recovery from Spent Catalyst Using Deep Eutectic Solvents.

Research Interests

Current prices of rhodium (Rh) and platinum (Pt) are in the top three most expensive metals in the platinum metal (PM) group; Rh having 55% increase in the price in the first month of 2020 reaching a 11-year high and Pt price having a steady increase of 24% in 2019 this is due to the extremely high demand and low supply. With the volume of Rh and Pt that are still mineable has currently not been documented it can be assumed that the amount of mineable Pt and Rh left is depleting rapidly. Being able to recover Rh and Pt from spent metal on metal oxide (MoMO) catalysts could decrease the current high demand for Rh and Pt. Leaching of Pt and Rh has little development due to both metals being highly unreactive to many acids and leaching mediums. This paper will investigate different leaching mediums, one of the lixiviants currently used in in industry, 1M aqua regia of HNO₃: HCl and four novel ionic liquids called Deep Eutectic Solvents (DES); ChCl (choline chloride): ethylene glycol (EG), ChCl: urea (Ur), ChCl: thiourea (TU) and ChCl: Lactic Acid (lac) to determine which once has the best recovery of Rh and Pt from a spent MoMO catalyst, this could potentially expand the current reagents used to recover Rh and Pt recovery from spent catalysts. One of the main findings was that all the DES, specifically lactic acid and urea DES, was found to show higher affinity towards Pt and Rh compared to the industry used aqua regia.