Development of a Rh-Intelligent Catalyst 2006-01-0851

We have developed a Pd-intelligent catalyst with a self-regenerative function that is realized by the passage of Pd through consecutive solid solution and segregation states in and out of a perovskite crystal, and commercialized it for the first time in the world [1, 2, 3, 4, 5, 6, 7, 8 and 9].

In this study, we investigated the self-regenerative function of Rh as an alternative for Pd, in two types of Rh-perovskite (LaFeRhO₃ and CaTiRhO₃), and found that a CaTiRhO₃ perovskite has an excellent capacity for the self-regenerative function of Rh. In a LaFeRhO₃ perovskite with a composition similar to the Pd-perovskite (LaFePdO₃), Rh was fixed so stably in the perovskite structure that it hardly segregated from the perovskite even in high temperature reduction atmospheres. However, in the CaTiRhO₃ perovskite, with its A²⁺B⁴⁺O₃ formula, the amount of Rh that actually segregated increased greatly in reduction atmospheres. Under re-oxidization atmospheres, all of the Rh that segregated were returned to the perovskite lattice. These results show that Rh in CaTiRhO₃ has an excellent self-regenerative function.

Due to the self-regenerative function of Rh and Pd, the full-scale Rh-Pd-intelligent catalyst containing a new CaTiRhO₃ perovskite and a Pd-perovskite (LaFePdO₃) exhibited excellent catalytic activity even after aging and this in spite of having reduced the amount of precious metals sharply.

The intelligent catalyst technology is expected to solve the problem of supply and demand for precious metals that has been deepening on a worldwide scale.