Abstract
Keywords - Intelligent catalyst, Self-regeneration, Three-way catalyst, Perovskite catalyst, Precious metals
Abstract- The intelligent catalyst (1) , which was reported in Nature journal, has attracted worldwide attention as an innovative technology in which precious metal regenerates itself in automotive exhaust gas without any auxiliary treatment. Here, the technical specifications of the intelligent catalyst are presented and its impact for society is also discussed.
With the strengthening of cold-emissions regulation, the demand for palladium (Pd) had increased to ten times since 1992. A new automotive catalyst technology that reduced precious metal consumption, especially Pd, was strongly desired.
In conventional catalysts, the catalytic activity deteriorates due to the particle growth of precious metals during vehicle use. We have developed a Pd-perovskite catalyst that has a function for the self-regeneration of Pd in the inherent fluctuation of the exhaust gas from current gasoline engines without requiring any auxiliary treatment. We named this technology the intelligent catalyst. Intelligent catalysts have been used practically as Japanese U-LEV catalysts since 2002.
Since cobalt carbonyl is classed as a carcinogenic by German TA-Luft, cobalt is eliminated from the composition of the catalyst for practical development. A new Co-free Pd-perovskite,
LaFePdO3, catalyst has been developed and it is confirmed that this perovskite catalyst also has the self-regenerative function, and that the catalyst demonstrates high catalytic activity and excellent crystal-structure stability. A new configuration for the intelligent catalyst is designed in order to maximize its self-regenerative function under practical conditions: double layer washcoats with LaFePdO3 perovskite catalyst in the lower layer and Pt and Rh in the upper layer. In this configuration, the intelligent catalyst maintains excellent catalytic activity even after accelerated aging reaching up to 1050 °C. The intelligent catalyst has been successfully adapted for practical use, meeting the Japan U-LEV standard while using much less precious metals than conventional catalysts prepared without a self-regenerative function.
We consider the intelligent catalyst as one of the solution for the precious metal demand and supply. And the intelligent catalyst is expected to become the global standard for automotive catalyst technology.