NOx storage-reduction catalysts for gasoline engines

The automotive catalyst technology is now faced with very difficult problems. As the result of automakers' efforts to produce more efficient and lower-emission vehicles, lean-burn gasoline engines have been introduced into the market. While these engines are much more efficient than conventional ones, NOx removal has become significantly more difficult. After enormous efforts, we succeeded in solving the problem, by inventing a new class of catalyst. We overcame two strict problems with the new type catalyst, which are sulfur poisoning and thermal deterioration. We have improved the support type and reformed the steam and substrate qualities by clarifying the related degradation mechanisms. Here our challenges to develop a new catalyst to store and then reduce NOx are described. The catalyst has made it possible to make emissions of lean-burn engines meet strict NOx regulations.