Towards nanotechnology-based catalytic converters for the automotive industry
Catalytic converters are now key components of most automotive exhaust systems contributing to major reductions in emissions. Three-way catalysts are state of the art. Most commonly, converters consist of a ceramic substrate coated with a precious metal-containing washcoat. A combination of platinum group metals (PGMs) including platinum, palladium and rhodium is often used. The European automotive industry uses huge quantities of PGMs, imposing large costs and depleting natural resources. The EU-funded NEXT-GEN-CAT (Development of next generation cost efficient automotive catalysts) project worked on low-cost, eco-friendly alternatives. The focus was on the use of nanoparticles (NPs) of transition metals such as copper, nickel and iron for partial or complete replacement of PGMs. Project partners developed efficient catalysts by incorporating low-cost transition metals into different substrates and advanced ceramics through the use of updated nanotechnology tools. To prepare active, transition metal-based automotive catalysts, they assessed different synthesis strategies. Various methods were used to characterise the developed materials, and the mechanisms involved during material preparation were identified. Using results from modelling as a basis, the NEXT-GEN-CAT team was able to further optimise the developed catalysts. It prepared and evaluated over 300 samples from various categories of materials, and assessed the catalytic efficiency of the prepared catalysts. Samples were ranked according to their efficiency, up-scalability and environmental impact. The project team then selected the two most promising materials for prototype development. Researchers up-scaled the two catalysts as aftertreatment systems, and determined the prototypes' performance according to EU emission standards in order to justify the sustainability of the developed automotive catalysts. To identify the most promising materials and establish the catalysts' sustainability, they assessed performance, cost, recyclability and environmental health. NEXT-GEN-CAT found that the developed materials exhibited lower environmental impact. Partial or complete replacement of PGMs with transition metal NPs in three-way catalysts should decrease costs, enhance sustainability and ensure reliable raw materials supply to EU manufacturers.
Keywords
Catalytic converters, three-way catalysts, platinum group metals, NEXT-GEN-CAT, automotive catalysts
