Change search
ReferencesLink to record
Permanent link

Direct link
Material characterization for studying thermal deactivation of automotive SCR catalysts
KTH, School of Chemical Science and Engineering (CHE).
2012 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Thermalageing of the commercial selective catalytic reduction catalysts used inScania’s trucks was investigated using catalyst characterization techniques.Catalyst samples were oven-aged at 550 °C for up to 990 hours and investigatedwith nitrogen adsorption, oxygen chemisorption, X-ray fluorescence, X-raydiffraction, X-ray photoelectron spectroscopy and temperature-programmeddesorption of ammonia. The two latter methods are new to Scania and wereevaluated in depth. Furthermore, field-aged samples, which had had theircatalytic performance tested in another study, were investigated, in an attemptto find some link between characterization results and catalytic activity. Theinvestigation of oven-aged samples yielded information about the timescales ofcarrier sintering and sintering of catalytically active material, showing theformer to be much slower than the latter. It was also noted that the rate withwhich the catalyst’s ability to store ammonia decreases during thermal ageingwas similar to the rate of sintering of catalytically active material,suggesting that the loss of ammonia storage capability due to thermal ageing isrelated to sintering of the catalytically active material. X-ray photoelectronspectroscopy revealed that the fraction of vanadium in the outermost surfacelayer of the catalysts had increased during ageing. At the same time, thischaracterization technique appeared to have a low repeatability, possibly dueto the investigated catalyst having a high surface inhomogeneity. Whether ornot 500 ppm of NOx was present in the ageing atmosphere did notappear to affect the deactivation of the catalyst. Finally, no clear link couldbe found between characterization results and catalytic activity for field-agedsamples.

Place, publisher, year, edition, pages
2012. , 84 p.
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-147524OAI: diva2:730247
Available from: 2014-06-27 Created: 2014-06-27 Last updated: 2014-06-27Bibliographically approved

Open Access in DiVA

fulltext(2900 kB)254 downloads
File information
File name FULLTEXT01.pdfFile size 2900 kBChecksum SHA-512
Type fulltextMimetype application/pdf

By organisation
School of Chemical Science and Engineering (CHE)
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 254 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 118 hits
ReferencesLink to record
Permanent link

Direct link