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Platinum oxidation and sulphur deactivation in NOx storage catalysts

Erik Fridell (Institutionen för teknisk fysik, Kemisk fysik ; Kompetenscentrum katalys (KCK)) ; Annika Amberntsson (Institutionen för teknisk fysik ; Kompetenscentrum katalys (KCK)) ; Louise Olsson (Institutionen för kemiteknik och miljövetenskap, Kemisk reaktionsteknik ; Kompetenscentrum katalys (KCK)) ; Ann W. Grant (Institutionen för teknisk fysik, Kemisk fysik) ; Magnus Skoglundh (Institutionen för material- och ytkemi, Teknisk ytkemi ; Kompetenscentrum katalys (KCK))
Topics in Catalysis (1022-5528). Vol. 30-31 (2004), 1-4, p. 143-146.
[Artikel, refereegranskad vetenskaplig]

Flow reactor experiments and X-ray photoelectron spectroscopy (XPS) measurements were used to investigate the importance of platinum oxide formation on Pt/BaO/Al2O3 NOx storage catalysts during reactions conditions. The reaction studied was NO(g) + 1/2 O-2(g) <----> NO2 (g). During NO2 exposure of the catalyst the NO2 dissociation rate decreased during the reaction. This activity decrease with time was also studied with XPS and it was found to be due to platinum oxide formation. The influence of sulphur exposure conditions on the performance of the NOx storage catalysts was studied by exposing the samples to lean and/or rich gas mixtures, simulating the conditions in a mixed lean application, containing SO2 The main results show that all samples are sensitive to sulphur and that the deactivation proceeds faster when SO2 is present in the feed under rich conditions than under lean or continuous SO2 exposure. Additionally, the influence of the noble metals present in the catalysts was investigated regarding sulphur sensitivity and it was found that a combination of platinum and rhodium seems to be preferable to retain high performance of the catalyst under SO2 exposure and subsequent regeneration. Finally, the behaviour of micro-fabricated model NOx storage catalysts was studied as a function of temperature and gas composition with area-resolved XPS. These model catalysts consisted of a thin film of Pt deposited on one-half of a BaCO3 pellet. It was found that the combination of SO2 and O-2 resulted in migration of Pt on the BaCO3 support up to one mm away from the Pt/BaCO3 interface.

Nyckelord: nitrogen oxides; NO; storage; platinum oxide; sulphur deactivation; XPS



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Denna post skapades 2008-02-13. Senast ändrad 2012-11-20.
CPL Pubid: 68228

 

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Institutioner (Chalmers)

Institutionen för teknisk fysik, Kemisk fysik (1900-2015)
Kompetenscentrum katalys (KCK)
Institutionen för teknisk fysik (1900-2015)
Institutionen för kemiteknik och miljövetenskap, Kemisk reaktionsteknik (2002-2004)
Institutionen för material- och ytkemi, Teknisk ytkemi (2002-2004)

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Energi
Materialvetenskap
Nanovetenskap och nanoteknik
Transport
Hållbar utveckling
Fysik
Kemiteknik

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