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Operando XAFS studies reveals differences in the activity of Fe-species in MFI and CHA structures for the standard selective catalytic reduction of NO with NH3

DOI: 10.1016/j.apcata.2018.11.026 DOI Help

Authors: Miren Agote-aran (University College of London; Research Complex at Harwell; Diamond Light Source) , Ines Lezcano-gonzalez (University College London; Research Complex at Harwell) , Alex G. Greenaway (University College London; Research Complex at Harwell) , Shusaku Hayama (Diamond Light Source) , Sofia Diaz-moreno (Diamond Light Source) , Anna B. Kroner (Diamond Light Source) , Andrew M. Beale (University College London; Research Complex at Harwell)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Applied Catalysis A: General

State: Published (Approved)
Published: November 2018
Diamond Proposal Number(s): 9925

Abstract: Fe-containing zeolites were studied as catalysts for the standard NH3-SCR reaction with the primary aim of gaining insight into the structure-function relationship of these materials. Catalysts with different Fe nuclearity (i.e. isolated species, clusters, large particles) were synthesised by incipient wetness impregnation, using H-ZSM-5, H-SSZ-13 and Silicalite-1 as supports, and characterised by in situ and operando X-ray emission spectroscopy (XES) and high energy resolution fluorescence detected X-ray absorption near-edge spectroscopy (HERFD-XANES) under NH3-SCR conditions. The combination of these techniques allowed us to obtain a detailed understanding of the changes in Fe coordination, oxidation state and geometry occurring during reaction. The results obtained suggested that isolated octahedral Fe3+ species on H-ZSM-5 are highly active under the conditions studied, undergoing reduction when exposed to NH3 or under SCR conditions. In contrast, isolated tetrahedral Fe3+ sites present in Silicalite-1 exhibited lower redox properties, leading to a reduced NO conversion. Clusters and FexOy particles on H-SSZ-13 exhibited low SCR activity.

Journal Keywords: NH3-SCR; NO; Fe-containing zeolites; HERFD-XANES; XES

Subject Areas: Chemistry

Instruments: I20-Scanning-X-ray spectroscopy (XAS/XES)

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