Fe-containing ZSM-11 zeolites as active catalyst for SCR of NOx: Part II. XAFS characterization and its relationship with the catalytic properties Original Research Article

This work describes the characterization by X-ray absorption spectroscopy (XAS) at Fe K-edge of the state of Fe in Fe-ZSM-11 zeolites prepared by novel sol–gel process used to decompose NOx to N2 by selective catalytic reduction (SCR), using iso-butane as reducer. Determining the Fe K-edge shift, the presence of Fen+ species in Fe-containing zeolite was determined and quantified. The symmetry and electronic characteristics of Fe in Fe-species are also discussed. The structural characteristics of the Fe species present in the catalysts are studied employing extended X-ray absorption fine structure spectroscopy. Fe2+, Fe3+ and Fe2O3 as isolated species were found as the active sites of the material for the SCR of NOx in concordance with Part I of this paper (Applied Catalysis, Part I, (2003)).