Chemistry Copper substituted zeolites have long been considered prime candidates as catalysts for reducing NOx
emissions
from exhaust fumes. Until recently, the catalytic cycle by which they work has not been fully understood, but researchers from the Technical University of Denmark (DTU) believe they may have finally found the answer
Spectroscopic investigations of copper substituted zeolites for catalysis
Stricter laws regarding emission
requirements for exhaust gases are being introduced in many countries around the world as concern for the environment increases. Reducing NOx
emissions from
the exhausts of diesel engines and power plants is an important part of this, which can be achieved through the selective catalytic reduction of NO to N2
by ammonia. Copper substituted zeolites
have been shown to be effective catalysts for this reaction. Copper chabazite has been proven to be particularly useful for application in diesel engines. These
catalysts will no doubt see
widespread use in the future, although a problem facing scientists studying them has been understanding the reactant mechanisms by which the occurs.
Suggestions have been
catalysis put
forward and all have had shortcomings, but Associate Professor Susanne Mossin
52
from the Department of Chemistry at the Technical University of Denmark believes that she and her collaborators at Haldor Topsøe A/S and the University of Turin have now solved the conundrum.
chemistry perspective, so in the end, rather than try and find fault in these suggestions, we tried to come up with a solution working from the very beginning, writing down all the possible
“After working on it for a while, everything suddenly fell into place and I could see straight away that we had something promising”
resonance
A specialist in electron paramagnetic (EPR)
spectroscopy, Mossin
originally approached the task by evaluating the existing literature. “I could see that the suggestions put forward for the mechanism did not seem right,” she explains. “I tend to approach these
challenges from an inorganic
reactions that could take place between the chemicals involved. After working on it for a while, everything suddenly fell into place and I could see straight away that we had something promising.” According to the scheme, which was
recently published in the journal ACS Catalysis, the reaction can be very simply
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