Miura, M., Aoki, Y., Kabashima, N., Fujiwara, T. et al., "Development of Advanced Three-Way Catalyst with Improved NOx Conversion," SAE Technical Paper 2015-01-1005, 2015, doi:10.4271/2015-01-1005.
Countries and regions around the world are tightening emissions regulations in reaction to the increasing awareness of environmental conservation. At the same time, growing concerns about the depletion of raw materials as vehicle ownership continues to increase is prompting automakers to look for ways of decreasing the use of platinum-group metals (PGMs) in the exhaust systems. This research has developed a new catalyst with strong robustness against fluctuations in the exhaust gas and excellent nitrogen oxide (NOx) conversion performance. This catalyst incorporates rhodium (Rh) clusters with a particle size of several nanometers, and stabilized CeO2-ZrO2 solid-solution (CZ) with a pyrochlore crystal structure as a high-volume oxygen storage capacity (OSC) material with a slow O2 storage rate. This catalyst also adopts enhanced zone coating technology that provides the optimum coating material in the direction of gas flow, thereby increasing the overall conversion performance balance and decreasing PGM usage by approximately 50%.