The Role of H+- and Cu+-Sites for N2O Formation during NH3-SCR over Cu-CHA
Journal article, 2021

The mechanism for N2O formation over CHA and Cu-CHA zeolite catalysts during NH3-SCR is investigated using density functional theory calculations. Direct NH4NO3 decomposition, which is commonly regarded as the main source of N2O, is found to be associated with high barriers in the absence of Brønsted acid sites. Although Brønsted acid sites promote NH4NO3 decomposition, it is still a highly activated process. Low-temperature N2O formation is instead found to be connected with an NO + NH3 reaction over Cu-sites. In particular, N2O can be formed from H2NNO with a low barrier over Cu-OOH-Cu complexes, which are proposed intermediates in the catalytic cycle for NH3-SCR over Cu-CHA. This finding provides an explanation for the experimentally observed low-temperature N2O formation and the relation between Cu loading and N2O formation. The proposed mechanisms open up strategies to enhance the selectivity to N2 during NH3-SCR.






Yingxin Feng

Chalmers, Physics, Chemical Physics

Ton V. W. Janssens


Peter N. R. Vennestrom


Jonas Jansson

Volvo Group

Magnus Skoglundh

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Henrik Grönbeck

Chalmers, Physics, Chemical Physics

Journal of Physical Chemistry C

1932-7447 (ISSN) 1932-7455 (eISSN)

Vol. 125 8 4595-4601

Subject Categories

Inorganic Chemistry

Physical Chemistry

Other Physics Topics

Driving Forces

Sustainable development


Basic sciences


C3SE (Chalmers Centre for Computational Science and Engineering)



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