PGM catalytic converters, Johnson Matthey, Umicore

The three-way catalyst cleans up petrol engines by depending on three scarce metals, platinum, palladium, rhodium, and a cerium oxygen buffer. Four formulators (Johnson Matthey, BASF, Umicore, Clariant) hold more than 70% of the market. This link connects chemistry to mining, PGMs come mostly out of Rustenburg, and its horizon narrows with electrification, which removes the exhaust altogether.