Physico-chemical properties of FeAlBEA and FeSiBEA zeolites and their catalytic activity in the SCR of NO with ethanol or methane

FeAlBEA and FeSiBEA zeolites are prepared by a conventional ion exchange and a two-step postsynthesis method, respectively. Their physico-chemical properties are investigated by XRD, FTIR, and diffuse reflectance UV–vis. For FeAlBEA zeolite, framework tetrahedral Fe(III), extra-framework octahedral Fe(III) and FeOx oligomers are observed by diffuse reflectance UV–vis. In contrast, for FeSiBEA mainly framework tetrahedral Fe(III) appears as a result of incorporation of Fe ions in vacant T-atom sites of SiBEA. The catalytic activity of FeAlBEA and FeSiBEA zeolites in the selective catalytic reduction of NO with ethanol or methane depends on the nature of iron and the presence of Al and Fe ions in the zeolite framework, respectively. The framework tetrahedral Al(III) and Fe(III) species, are origin of strong Brønsted and Lewis acidic centres which may influence the catalytic properties of FeAlBEA and FeSiBEA zeolite. FeAlBEA catalyst with higher strength and amount of these centres than FeSiBEA ones is more active and much more selective toward N2 in SCR of NO with methane.