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Improving The Catalytic Converters Of Motor Vehicles

Date:
June 2, 2009
Source:
CNRS (Délégation Paris Michel-Ange)
Summary:
The chemical mechanism that occurs on the surface of an automotive catalytic converter has been deciphered thanks to an observation speed record. This performance has made it possible to characterize this key step in the reaction that ensures pollutant removal by automotive converters. The challenge is indeed considerable: to obtain a clearer understanding of the mechanisms of removal catalysts in order to improve converters and other catalysts used by the automotive industry.
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The chemical mechanism that occurs on the surface of an automotive catalytic converter has been deciphered thanks to an observation speed record established by Frédéric Thibault-Strarzyk at the Laboratoire Catalyse et Spectrochimie in Caen (CNRS-Ensicaen).

This performance, achieved in collaboration with the University of Cambridge, has made it possible to characterize this key step in the reaction that ensures pollutant removal by automotive converters. The challenge is indeed considerable: to obtain a clearer understanding of the mechanisms of removal catalysts in order to improve converters and other catalysts used by the automotive industry.

These results were published in Science on May 22, 2009.

A catalytic converter included in a vehicle's exhaust system is a solid element that converts the toxic gases generated by the engine into a mixture of inoffensive gases. Although these catalysts are widely employed, their chemical mechanisms have hitherto been poorly understood.

In addition to improving catalytic converters, this observation technique will also help to understand many of the other pollutant removal systems used by industry.

The observation of very fleeting types of catalysts in the context of these mechanisms is particularly challenging. Until now, the most rapid observations of the surface of these catalysts using infrared methods were around one-tenth of a second.

A novel combination of observation methods has now reduced the duration of observations by a factor of one million.

This manipulation was achieved using a femtosecond laser which was focused on the surface of the solid catalyst made up of silver nanoparticles on an alumina substrate and placed in an atmosphere of toxic gases, thus recreating the conditions of a converter in an exhaust system. As soon as the reaction was triggered by the laser beam, an infrared spectrometer analyzed the surface of the catalyst at a rate of 30 million observations per second. The key intermediate step in the removal reaction was thus observed for the first time and consisted in a cyanide flip between the silver nanoparticles and the substrate. This molecular flip only lasted 2 microseconds and indeed explains how the removal catalyst functions.


Story Source:

The above post is reprinted from materials provided by CNRS (Délégation Paris Michel-Ange). Note: Materials may be edited for content and length.


Journal Reference:

  1. Frédéric Thibault-Starzyk, Etienne Seguin, Sébastien Thomas, Marco Daturi, Heike Arnolds, and David A. King. Real-Time Infrared Detection of Cyanide Flip on Silver-Alumina NOx Removal Catalyst. Science, 2009; 324 (5930): 1048 DOI: 10.1126/science.1169041

Cite This Page:

CNRS (Délégation Paris Michel-Ange). "Improving The Catalytic Converters Of Motor Vehicles." ScienceDaily. ScienceDaily, 2 June 2009. <www.sciencedaily.com/releases/2009/05/090529075000.htm>.
CNRS (Délégation Paris Michel-Ange). (2009, June 2). Improving The Catalytic Converters Of Motor Vehicles. ScienceDaily. Retrieved September 4, 2015 from www.sciencedaily.com/releases/2009/05/090529075000.htm
CNRS (Délégation Paris Michel-Ange). "Improving The Catalytic Converters Of Motor Vehicles." ScienceDaily. www.sciencedaily.com/releases/2009/05/090529075000.htm (accessed September 4, 2015).

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