Development of Advanced Zone-Coated Three-Way Catalysts 2011-01-0296
In recent years the regulations governing emissions from
automobiles have been strengthened as awareness of global
environmental problems has increased. Furthermore, the amount of
precious metals being used has continued to decrease due to
concerns over the exhaustion of natural resources and worries about
the risk of fluctuations in the price of these precious metals. As
a result, a high performance three-way catalyst that can satisfy
the emissions regulations is now required.
By applying zone-coating and carrier degradation control
technology, a high performance three-way catalyst has been
developed. The zone-coating technology improves the conversion
performance of the catalyst through improvement of HC and
NOx conversion reactions and oxygen storage capacity
(OSC) reactions. The addition of an Nd surface-enriched layer
strengthened the mutual interactions between the carrier and Rh.
Moreover, the introduction of an alumina diffusion barrier
suppresses ZrO₂ sintering which in turn suppresses Rh grain growth.
The new three-way catalyst has adopted these technologies and
substantially less Rh is needed compared to conventional catalysts.
In addition, this new catalyst is scheduled to be adopted into
vehicles starting 2011.