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Emission of Toxic HCN During NOx Removal by Ammonia SCR in the Exhaust of Lean-Burn Natural Gas Engines

Zengel, D. 1; Koch, P. 1; Torkashvand, B. 1; Grunwaldt, J.-D. ORCID iD icon; Casapu, M. 1; Deutschmann, O. ORCID iD icon 1
1 Institut für Technische Chemie und Polymerchemie (ITCP), Karlsruher Institut für Technologie (KIT)


Reducing greenhouse gas and pollutant emissions is one of the most stringent priorities of our society to minimize their dramatic effects on health and environment. Natural gas (NG) engines, in particular at lean conditions, emit less CO$_{2}$ in comparison to combustion engines operated with liquid fuels but NG engines still require emission control devices for NO$_{x}$ removal. Using state‐of‐the‐art technologies for selective catalytic reduction (SCR) of NO$_{x}$ with NH$_{3}$, we evaluated the interplay of the reducing agent NH$_{3}$ and formaldehyde, which is always present in the exhaust of NG engines. Our results show that a significant amount of highly toxic hydrogen cyanide (HCN) is formed. All catalysts tested partially convert formaldehyde to HCOOH and CO. Additionally, they form secondary emissions of HCN due to catalytic reactions of formaldehyde and its oxidation intermediates with NH$_{3}$. With the present components of the exhaust gas aftertreatment system the HCN emissions are not efficiently converted to non‐polluting gases. The development of more advanced catalyst formulations with improved oxidation activity is mandatory to solve this novel critical issue.

Verlagsausgabe §
DOI: 10.5445/IR/1000122748
Veröffentlicht am 30.08.2020
DOI: 10.1002/anie.202003670
Zitationen: 32
Zitationen: 34
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Technische Chemie und Polymerchemie (ITCP)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 17.08.2020
Sprache Englisch
Identifikator ISSN: 0044-8249, 0570-0833, 1433-7851, 1521-3757, 1521-3773
KITopen-ID: 1000122748
Erschienen in Angewandte Chemie / International edition
Verlag John Wiley and Sons
Band 59
Heft 34
Seiten 14423-14428
Vorab online veröffentlicht am 11.05.2020
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