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

Posted: August 17, 2017 by oldbrew in Emissions, pollution, research, Travel

Diesel car engine


Diesels are in need of some good news after all the recent negative press. The researchers believe their findings are of ‘major environmental importance’.

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, as Phys.org reports.

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.

“The results here point to a previously unrecognized catalytic mechanism and also point to new directions for discovering better catalysts,” said William Schneider, the H. Clifford and Evelyn A. Brosey Professor of Engineering at the University of Notre Dame. “This is a reaction of major environmental importance used to clean up exhaust.”

Continued here.

Comments
  1. Bob Greene says:

    Interesting. Normal SCR requires much higher temperatures and ~350°C is required if your NH3 source is aqueous urea. Are they planning to use ammonia solution? Handling aqueous NH3 sounds like a problem for things moving about.

    Zeolites are not unusual SCR catalysts. The copper is what’s new.

    It might get lower with this copper catalyzed zeolite. http://pubs.acs.org/doi/abs/10.1021/ie034052j?journalCode=iecred

  2. oldbrew says:

    A bit off-topic…
    ‘Yellowstone could power America’s electric cars with newly discovered supervolcano lithium’

    http://www.ibtimes.co.uk/yellowstone-could-power-americas-electric-cars-newly-discovered-supervolcano-lithium-1635294

    Industrialising a renowned national park?

  3. Gamecock says:

    Still awaiting proof that ground-level nitrogen oxides are a health hazard. This ‘new catalyst design’ is an ingenious solution to a non existent problem.

    https://junkscience.com/2016/07/epa-documents-show-vw-cheating-posed-no-threat-to-public-health/#more-90064

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