Abstract
An intelligent catalyst", which has the self-regenerative function of Pd realized through solid solution and segregation of Pd in a perovskite crystal, was first commercialized in 2002. Attempts have been made to apply this intelligent technology to other precious metals, such as Rh and Pt, and advanced intelligent catalysts with a self-regenerative function of Rh and Pt have been developed successfully.
In this study, we investigated a self-regenerative function of Rh with the same view as Pd, in two types of Rh perovskite oxides (LaFeRhO3 and CaTiRhO3) by using X-ray Absorption Fine Structure analysis (XAFS), and found that the CaTiRhO3 perovskite oxide has an excellent self-regenerative function of Rh. A design configuration of precious metalcontaining perovskite catalysts for a practical monolithic catalyst was discussed. Precious metal-containing perovskite catalysts (CaTiRhO3, LaFePdO3, and CaZrPtO3) were located in double-layers to maximize their performance. Such a catalyst was attached to an engine exhaust system and subjected to accelerated aging. The bed temperature of the catalyst reached 1050 °C. The performance of the catalyst was evaluated on an engine dynamometer. This advanced intelligent catalyst exhibited an excellent activity under practical conditions and required a reduced loading of precious metals through its self-regenerative function. This advanced catalyst was named "A Super-Intelligent Catalyst".
The intelligent catalyst technology is expected to solve problems of supply and demand for precious metals that have been deepening on a worldwide scale.
Keywords:Intelligent catalyst, Self-regenerative function, Three-way catalyst, Perovskite catalyst, Precious metals