New catalysts to cut emissions?

Materials World magazine
,
4 Oct 2017

A project featuring universities and a diesel engine manufacturer has uncovered a new mechanism that could help reduce NOx emissions.

The findings, published in Science, detail how a previously unrecognised catalytic reaction could improve efficiency at lower temperatures. 

Co-leader of the project, Rajamani Gounder, the Larry and Virginia Faith Assistant Professor of Chemical Engineering at Purdue University’s Davidson School of Chemical Engineering, USA, said, ‘The key challenge in reducing emissions is that they can occur over a very broad range of operating conditions, and especially exhaust temperatures. 

‘Perhaps the biggest challenge is related to reducing NOx at low exhaust temperatures, for example during cold start or in congested urban driving.’ 

Gounder’s team, made up of researchers from Purdue, as well as the University of Notre Dame, USA, and engine manufacturer, Cummins, worked with zeolites, which have a crystalline structure that contains pores approximately 1nm in diameter. These were filled with copper-atom active sites and led researchers to discover that when ammonia is introduced into the exhaust, it solvates the copper ions and creates a catalytic reaction. 

Copper-ammonia can speed up the bond-breaking reaction of oxygen molecules. Researchers are looking at reducing the temperature at which this occurs.

‘The results here point to a previously unrecognised catalytic mechanism and also point to new directions for discovering better catalysts,’ explained William Schneider, the H Clifford and Evelyn A Brosey Professor of Engineering at Notre Dame.