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1533220 
Journal Article 
Relevance of Co, Ag-ferrierite catalysts acidity and cation siting to CH4-NOx-SCR activity 
Ciambelli, P; Sannino, D; Palo, E; Gargano, G; Balboni, E; Martucci, A; Dalconi, MC; Alberti, A 
2008 
123 
10-11 
1583-1595 
WOS:000265051900021 
The influence of acidity on Ag,Co exchanged ferrierite
obtained from different parent forms was tested in CH4-DeNO(x) reaction. Ag and Co cation siting
distribution and residual zeolite acidity were evaluated by means of a quantitative evaluation of
catalyst acidity through NH3-TPD experiments and a detailed structural catalyst characterization
by Rietveld refinement. A new nomencluature for the cation sites in hydrated and dehydrated
cation exchange ferrierites was introduced for sake of clarity. The sites relative populations
obtained by the UV-Vis spectra did not agree with the values given by the Rietveld refinement and
the SCR activity scale since the high abundance of Co cations in the retained most active
position, Co2a, was shown by the less active catalyst obtained from the Na,K form. It was
concluded that SCR, activity does not; only depend on Co and Ag siting within the zeolite
framework but also by the presence of residnal acidity evidenced on the most active catalysts.
CH4 combustion tests showed that the presence of residnal acidity appears relevant to SCR
catalytic performances, likely related to its ability in methane activation. The importance of
the coexistence, of Co and zeolitic acid sites for the HC-SCR suggested that SCR reaction could
proceed on a dual site.