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Structure-function relationship for alumina supported platinum during formation of ammonia from nitrogen oxide and hydrogen in presence of oxygen

Emma Adams (Institutionen för kemi och kemiteknik, Teknisk ytkemi ; Kompetenscentrum katalys (KCK)) ; Lindsay Merte ; Anders Hellman (Institutionen för fysik (Chalmers) ; Kompetenscentrum katalys (KCK)) ; Magnus Skoglundh (Institutionen för kemi och kemiteknik, Teknisk ytkemi ; Kompetenscentrum katalys (KCK)) ; Johan Gustafson ; Eva Benedixen ; Pär Gabrielsson ; Florian Bertram ; Jonas Evertsson ; Chu Zhang ; Stefan Carlson ; Per-Anders Carlsson (Institutionen för kemi och kemiteknik, Teknisk ytkemi ; Kompetenscentrum katalys (KCK))
Physical Chemistry Chemical Physics - PCCP (1463-9076). Vol. 18 (2016), 16, p. 10850-10855.
[Artikel, refereegranskad vetenskaplig]

We study the structure-function relationship of alumina supported platinum during forma- tion of ammonia from nitrogen oxide and dihydrogen by employing in situ X-ray absorption and Fourier transformed infrared spectroscopy. Particular focus is directed towards the effect of increased levels of oxygen on the reaction as a model system for emerging technologies for passive selective catalytic reduction of nitrogen oxides. The suppressed formation of ammo- nia observed as the feed becomes net-oxidizing is accompanied by a considerable increase in the oxidation state of platinum as well as enhanced formation of surface nitrates and loss of NH-containing surface species. In the presence of (excess) oxygen, the ammonia formation is proposed to be limited by the weak interaction between nitrogen oxide and the oxidized platinum surface. This leads to slow dissociation rate of nitrogen oxide and thus low abun- dance of atomic nitrogen surface species that can react with adsorbed hydrogen atoms. In this case the consumption of hydrogen through the competing water formation reaction and decomposition/oxidation of ammonia are of less importance for the net ammonia formation.



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Denna post skapades 2016-03-30. Senast ändrad 2016-05-27.
CPL Pubid: 233920