New oxygen storage material

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Development background of the new oxygen storage material

CeO₂-ZrO₂ solid solution (CZ) adjusts fluctuating atmosphere of emission in the 3-way automotive catalyst. In the purification activity, it has an oxygen storage capacity (OSC) that keeps reduction activity especially of nitrogen oxide (NOx). Recent years, technology to reduce NOx emission is required in order to deal with "Emission gas regulation" which is getting to be more severe. So we focused on "NOx emission behavior" in the oxygen concentration variation range in emission gas and aimed at "Expanding active region when variation of oxygen concentration." Then we have successfully developed "New oxygen storage material (＝pCP：persistent Ceria-Zirconia Pyrochlore type solid solution)" that its active region is expanded when oxygen concentration variation. This technology has been jointly developed by Toyota Central R&D Labs., Inc., Toyota Motor Corporation, and Cataler. We received Chemical Technology Award from The Chemical Society of Japan in March 2015, and Technology Award from The Ceramic Society of Japan in June 2016.

Material that expanded active region at oxygen concentration fluctuation

With existing materials for processing catalyst, nitrogen oxide(NOx) was not purified when oxygen flow was more than storage capacity because precious metal was deactivated due to "low capacity of oxygen storage" Our "New oxygen storage material (pCP)" has LARGE storage capacity and SLOW storage characteristics so it is possible to occlude excess oxygen. In fact, it is possible to purify "NOx" maintaining activated condition by keeping metallic state of precious metal.

Fluorite structure

Pyrochlore structure

Effect of the new oxygen storage material

Our new oxygen storage material has large capacity and "slow oxygen storage characteristics "so it is possible to get closer to "oxygen storage characteristic "that is desired as catalyst compared to existing material. Therefore, it can drastically suppress "NOx" emission in the oxygen concentration variation region.