On the role of H2 to modify surface NOx species over Ag-Al2O3 as lean NOx reduction catalyst: TPD and DRIFTS studies
Artikel i vetenskaplig tidskrift, 2015

Formation and stability of surface NOx species related to the promotional effect of H2 over Ag–Al2O3 as NOx reduction catalyst were investigated with temperature-programmed desorption and DRIFT spectroscopy. Formation of two groups of surface NOx species was found: a less thermally stable group of “low temperature (LT) species” and a more thermally stable group of “high temperature (HT) species”. The LT NOx was attributable to the decomposition of surface NOx species formed on the active sites where its elimination by addition of H2 or thermal decomposition correlated with higher NO oxidation and NOx reduction conversion. Under reaction conditions, these possibly inhibiting LT NOx species were stable up to about 300 °C and their formation depended on donation of oxygen from surface oxides. Removal of LT nitrate species by H2 accounted for only a fraction of the increased NO oxidation and NOx reduction conversion by co-feeding H2. Furthermore, it was also found that H2 facilitates formation of HT NOx that primarily corresponded to the decomposition of spectator species on the Al2O3 support identified as monodentate nitrate species. From TPD studies of C3H6-SCR, it was shown that H2 not only eliminated LT NOx but also promoted formation of greater quantities of adsorbed hydrocarbons.

HC-SCR

DRIFT

NOx reduction

TPD

Hydrogen effect

Silver alumina

Författare

Muhammad Mufti Azis

Kompetenscentrum katalys

Chalmers, Kemi och kemiteknik, Kemiteknik

Hanna Härelind

Kompetenscentrum katalys

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Derek Creaser

Chalmers, Kemi och kemiteknik, Kemiteknik

Catalysis Science and Technology

2044-4753 (ISSN) 2044-4761 (eISSN)

Vol. 55 1 296-309

Modellutveckling för heterogena katalytiska reaktorer

Vetenskapsrådet (VR) (2011-3926), 2012-01-01 -- 2014-12-31.

Styrkeområden

Transport

Ämneskategorier

Kemiska processer

Kemi

DOI

10.1039/C4CY00816B

Mer information

Skapat

2017-10-08