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Arthur T Knackerbracket has found the following story:

Automobiles are facing increasingly strict emissions regulations in an effort to reduce the amount of harmful air pollutants that are released into the environment. In Japan, for example, the current emissions standards for NO_x and nonmethane hydrocarbons are less than 0.05 g/km. Currently, one method of reducing harmful emissions is with a high-performance, three-way catalytic (TWC) converter. This device reduces harmful nitrogen oxides to nitrogen and oxygen, oxidizes carbon monoxide to carbon dioxide, and oxidizes unburnt hydrocarbons to carbon dioxide and water. However, it requires the use of the rare-earth element Cerium (Ce), which is increasing in price and can suffer from supply problems. Professor Masato Machida from Kumamoto University, Japan has been researching ways to reduce the amount of Ce used in catalytic converters and even find an alternative material to replace it.

In their most recent attempt to reduce the amount of Ce in their experimental catalyst, Professor Machida and collaborators from Japan's National Institute of Advanced Industrial Science & Technology (AIST) grafted cerium oxide to MnFeO_y (CeO₂/MnFeO_y), and compared their new catalyst with two reference catalysts, CeO₂/Fe₂O₃ and CeO₂/Mn₂O₃. Upon assessing the oxygen-release profiles through carbon monoxide temperature-programmed reduction (CO-TPR), the researchers found that even though CeO₂/Mn₂O₃ exhibited oxygen release rates greater than CeO₂/MnFeO_y between ~350 to ~550 degrees Celsius, the experimental catalyst started releasing at the lowest possible temperature. This provided evidence that oxygen release was improved by both combining Fe₂O₃ and Mn₂O₃, and grafting CeO₂ to the surface.

[...] The researchers then put their new catalyst to the test in conditions that more closely resembled the real world. Using the Japanese standard JC08 (hot start) mode for gasoline engines, they developed two (reference and experimental) real-sized honeycomb catalysts and compared their performance using a four cylinder, 1339 cc, gasoline engine on a chassis dynamometer. The experimental catalyst was a 1:2 wt ratio of 1 wt% Rh-loaded CeO₂/MnFeO_y and 2.5 wt% Pd/A₂O₃, and the reference catalyst was a mixture of 1 wt% Rh/CeO₂ and Pd/A₂O₃. The experimental catalyst used 30% less CeO₂ than the reference thereby reducing the need for the rare earth metal.

-- submitted from IRC

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