Effect of hydrogen sulphide on nitric oxide adsorption and decomposition on Cu-containing molecular sieves

NO adsorption and decomposition were studied on sulphided and sulphated cop per-exchanged ZSM-5, AlMCM-41 and NbMCM-41 molecular sieves. FTIR, temperat ure-programmed reduction (H-2-TPR) techniques, adsorption, and catalytic me asurements were applied. H2S adsorption drastically decreases the activity of copper-containing micro- and mesoporous materials studied in NO decompos ition due to their sulphidation. This decrease is higher than that observed after SO2 treatment and is assigned to the formation of sulphide species. H2S is strongly chemisorbed on all copper active sites. Oxidation of sulphi de species leading to the formation of sulphates does not increase the acti vity in the decomposition of NO, suggesting that some sulphided species are not oxidised. (C) 2000 Elsevier Science B.V. All rights reserved.