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Promotional effect of S02 on the selective catalytic reduction of NOx with propane/propene over Ag!')'-AI20 3

par Angelidis, T.N.;Kruse, Norbert
Référence Applied catalysis. B, Environmental, 34, page (201-212)
Publication Publié, 2001-05-30

Article révisé par les pairs

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Résumé :

Long-term isothermal studies of the ml1ucncc of S02 on the deNOx activity of a medium loaded (5 WI.%) Ag/-y-Al2O3 catalyst were performed under lean-hum conditions at 480°C. using a propane/propene mixture as reductant. The presence of S02 in the feed seems to have a promotional effect on the deNOx activity. This effect was clear over long-term experiments up to 15h and the catalyst activity stabilises earlier in the presence of S02. The forrnation of hydrocarbon oxygenates. sulphur species accumulation on the catalyst and changes in the deNOx reaction mechanism seem to be responsible for the promotional effect. Considerable quantities of sulphur species were accumulated on the catalyst during the first hours time-on-stream, when the promotional effect was more intensive. Interactions between S02 and NOx and between S02 and the hydrocarbons were the major sources of sulphur species accumulation with the S02/NOx interactions having the larger contribution. TPD studies after catalyst pre-treatment in different reaction mixtures provided evidence for the formation of RSOx species. The interaelions between S02 and the other feed constituents show that the usually applied ex situ sulphation treatmenl by S02/02 mixtures does not simulate the actual sulphat ion procedure.