In situ FTIR study of SO2 interaction with Pt/BaCO3/Al2O3 NOx storage catalysts under lean and rich conditions

• The interaction of SO2 with Pt/BaCO3/Al2O3 NOx storage catalysts under lean and rich conditions in the absence and presence of water was investigated by means of in situ FTIR spectroscopy at 350 degrees C. For the lean condition (SO2 + O-2), surface and bulk barium sulfates were formed in addition to sulfites and surface sulfates on alumina. Pt does not appear to play an essential role in the formation of these species under lean conditions. In contrast, under reducing conditions (SO2 + H-2), Pt catalysed the reduction of SO2 with H-2 to form reduced sulfur species that accumulate on both Pt and barium sites. A subsequent treatment with NO2 resulted in the reduction of NO2 in the oxidation of these sulfur-containing species to form bulk barium sulfate instead of being stored over barium sites. Introducing water significantly affected sulfur trapping over the catalyst surface. During the lean conditions, the presence of water resulted in almost no surface barium sulfate formation. Meanwhile, the formation of bulk barium sulfate was increased, probably due to enhanced sulfate formation. However, the presence of H2O under reducing conditions resulted in significantly lower sulfur storage on both barium and alumina in comparison with humid lean exposure conditions.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Annan teknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Other Engineering and Technologies (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering (hsv//eng)

Nyckelord

H2O

Pt/BaCO3/Al2O3 catalyst

NOx storage catalyst

sulfur poisoning

DRIFT

lean NO2 reduction

SO2

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art (ämneskategori)

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