Discovery could lead to new catalyst design to reduce nitrogen oxides in diesel exhaust

Researchers have discovered a new reaction mechanism that could be used to improve catalyst designs for pollution control systems to further reduce emissions of smog-causing nitrogen oxides in diesel exhaust.

The research focuses on a type of catalyst called zeolites, workhorses in petroleum and chemical refineries and in emission-control systems for diesel engines.

New catalyst designs are needed to reduce the emission of nitrogen oxides, or NOx, because current technologies only work well at relatively high temperatures.

“The key challenge in reducing emissions is that they can occur over a very broad range of operating conditions, and especially exhaust temperatures,” said Rajamani Gounder, the Larry and Virginia Faith Assistant Professor of Chemical Engineering in Purdue University’s Davidson School of Chemical Engineering. “Perhaps the biggest challenge is related to reducing NOx at low exhaust temperatures, for example during cold start or in congested urban driving.”

However, in addition to these “transient” conditions, future vehicles will naturally operate at lower temperatures all the time because they will be more efficient.

“So we’re going to need catalysts that perform better not only during transient conditions, but also during sustained lower exhaust temperatures,” Gounder said.

He co-led a team of researchers who have uncovered an essential property of the catalyst for it to be able to convert nitrogen oxides. Findings will be published online in the journal Science on Thursday (Aug. 17) and will appear in a later print issue of the magazine.

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