Quantification of urea-spray non-uniformity effects on the H2-assisted NO reduction and NH3 slip over an Ag/Al2O3 catalyst
Paper in proceeding, 2015

Selective catalytic reduction of nitrogen oxides (NOx) with ammonia (NH3-SCR) is an efficient technology for lean NOx removal in automotive applications. In the current work, a kinetic model for hydrogen-assisted NH3-SCR over a silver-alumina (Ag/Al2O3) monolith catalyst is adapted to the corresponding experimental results. The degree of non-uniformity in the NH3 dose to individual catalyst channels during operation of a urea-SCR system is also investigated and the NH3 dose probability distribution functions are derived. The effects of NH3 non-uniformity on the NO conversion and NH3 slip are studied over an otherwise optimal Ag/Al2O3 system. Above the stoichiometric point, the NH3 slip is shown to increase almost linearly with increasing NH3 dosage. Channels that receive significantly lower NH3 dose than the stoichiometric one exhibit low NO conversion, whereas there is no discernable increase in the NO conversion above an NH3 dose four times the average. These results highlight the importance of the interaction between the design of the NH3 dosing system and the performance of the catalytic system.

NH3 slip



NOx reduction


Linda Ström

Competence Centre for Catalysis (KCK)

Henrik Ström

Chalmers, Applied Mechanics, Fluid Dynamics

Andreas Darnell

Nilcon Engineering AB

Per-Anders Carlsson

Competence Centre for Catalysis (KCK)

Magnus Skoglundh

Competence Centre for Catalysis (KCK)

Hanna Härelind

Competence Centre for Catalysis (KCK)

Energy Procedia

18766102 (ISSN)

Vol. 75 2317-2322

The 7th International Conference on Applied Energy (ICAE2015)
Abu Dhabi, United Arab Emirates,

Fundamental studies of active sites and reaction mechanisms for lean NOx reduction over Ag-alumina

Swedish Research Council (VR), 2012-08-15 -- 2018-08-31.

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