NO TPD AND H-2-TPR STUDIES FOR CHARACTERIZATION OF CUMOR CATALYSTS THE ROLE OF SI AL RATIO, COPPER CONTENT AND COCATION/

NO TPD, H-2-TPR and XRD have been used to characterise copper-exchange d mordenites with different Si/Al ratios, copper contents and cocation s. The results showed that copper is mainly in the form of isolated Cu 2+ ions in CuMOR catalysts with copper exchange less than or equal to 20%, whereas at higher copper exchange CuO species are also present. T hese results were obtained with H and Na as cocation and were achieved by changing either the catalyst Si/Al ratio or the copper content. Th e data also indicate that the cocation mainly affects copper location and that copper is more easily reduced in sodium form catalysts than i n protonic form. It was found that the isolated Cu2+ ions are the most effective species for NO adsorption and the most active species for N O SCR. (C) 1997 Elsevier Science B.V.