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The effect of potassium inclusion in a silver catalyst for N2O-mediated oxidation of soot in oxidising exhaust gases

Cooper, Anna, Golunski, Stan ORCID: https://orcid.org/0000-0001-7980-8624 and Taylor, Stuart H. ORCID: https://orcid.org/0000-0002-1933-4874 2022. The effect of potassium inclusion in a silver catalyst for N2O-mediated oxidation of soot in oxidising exhaust gases. Catalysts 12 (7) , 753. 10.3390/catal12070753

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Abstract

It has previously been shown that an Ag/CZA catalyst can simultaneously remove NOx and soot from an oxygen-rich exhaust gas at low temperatures, by utilising the N2O generated preferentially during incomplete NOx reduction. Here, we examine the effect of reformulating the catalyst to include potassium, which is a known promoter of soot combustion. On including 2 wt% K, NOx-reduction occurs both in the absence and presence of soot, but the N2O formed does not play a part in the oxidation of soot. At higher K loadings (5, 10 and 15 wt%), NOx reduction is almost completely disabled, and only contributes to the activity of the catalyst containing 5 wt% K when tested in the presence of soot. At a loading of 20 wt% K, the potassium phase segregates, leaving NO and NH3 adsorption sites exposed. In the absence of soot, this catalyst can remove NOx by reduction on the Ag/CZA component and through nitration of the potassium phase. Although the presence of potassium lowers the onset temperature for soot oxidation to within the range of NOx reduction over Ag/CZA, the mobile K species prevents the desirable C+N2O reaction.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Cardiff Catalysis Institute (CCI)
Additional Information: This is an open access article distributed under the Creative Commons Attribution License
Publisher: MDPI
ISSN: 2073-4344
Funders: EPSRC
Date of First Compliant Deposit: 12 July 2022
Date of Acceptance: 5 July 2022
Last Modified: 30 Nov 2022 08:19
URI: https://orca.cardiff.ac.uk/id/eprint/151253

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