Activation of oxygen on (NH3–Cu–NH3)+ in NH3-SCR over Cu-CHA
Artikel i vetenskaplig tidskrift, 2018

Cu-CHA materials are efficient catalysts for NH 3 –SCR of NO x in oxygen excess. A crucial step in the reaction is oxygen (O 2 ) activation, which still is not well understood. Density functional theory calculations in combination with ab initio thermodynamics and molecular dynamics are here used to study O 2 dissociation on Cu(NH 3 ) 2 + species, which are present under NH 3 –SCR conditions. Direct dissociation of O 2 is found to be facile over a pair of Cu(NH 3 ) 2 + complexes whereas dissociation on a single Cu(NH 3 ) 2 + species is unlikely due to a high activation energy. The presence of NO promotes oxygen dissociation on both single and pairs of Cu(NH 3 ) 2 + complexes. Nitrites and nitrates are easily formed as O 2 dissociates, and NO adsorption over nitrates leads to facile formation of NO 2 . The results stress the importance of ligand-stabilized Cu species in Cu-CHA catalysts for NH 3 –SCR.

O2-activation

DFT

Cu diamine complex

Chabazite

NH3–SCR

Författare

Lin Chen

Hanne Falsig

Haldor Topsoe

Ton Janssens

Haldor Topsoe

Henrik Grönbeck

Chalmers, Fysik, Kemisk fysik

Kompetenscentrum katalys (KCK)

Journal of Catalysis

0021-9517 (ISSN) 1090-2694 (eISSN)

Vol. 358 179-186

Ämneskategorier

Oorganisk kemi

Annan kemi

Organisk kemi

DOI

10.1016/j.jcat.2017.12.009

Mer information

Senast uppdaterat

2018-03-29