Closing the loop on platinum from catalytic converters: Contributions from material flow analysis and circularity indicators
In this study, material flow analysis (MFA) is applied to quantify and reduce the obstacles for advancing a circular economy (CE) of platinum (Pt) from catalytic converters (CC) in Europe. First, the value chain and related stakeholders are mapped out in an MFA-like model to both facilitate the assessment of stocks and flows, and get a comprehensive view of potential action levers and resources to close-the-loop. Then, through the cross analysis of numerous data sources, two MFA are completed: (i) one general MFA, and (ii) one sector-specific MFA, drawing a distinction between the fate of Pt from (a) light-duty vehicles, under the European Union's End of Life Vehicle Directive 2000/EC/53, and (b) heavy-duty and off-road vehicles. Key findings reveal a leakage of around 15 tons of Pt outside the European market in 2017. Although approximately one quarter of the losses are due to in-use dissipation, 65% are attributed to insufficient collection and unregulated exports. Comparing the environmental impact between primary and secondary production, it has been estimated that halving the leakage of Pt during usage and collection could prevent the energetic consumption of 1.3 × 103 TJ and the greenhouse gases emission of 2.5 × 102 kt CO2 eq. Through the lens of circularity indicators, activating appropriate action levers to enhance the CE performance of Pt in Europe is of utmost importance in order to secure future production of new generations of CC and fuel cells. Moreover, the growing stockpile of Pt from CC in use indicates the need for better collection mechanisms. Also, the CC attrition during use and associated Pt emissions in the environment appears non-negligible. Based on the scarce and dated publications in this regard, we encourage further research for a sound understanding of this phenomenon that can negatively impact human health.