1. Fe Speciation in Iron Modified Natural Zeolites as Sustainable Environmental Catalysts.
- Author
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Chávez Rivas, Fernando, Rodríguez-Iznaga, Inocente, Berlier, Gloria, Tito Ferro, Daria, Concepción-Rosabal, Beatriz, and Petranovskii, Vitalii
- Subjects
ZEOLITES ,CHEMICAL speciation ,NITROSYL compounds ,IRON ,NITROGEN oxides ,MORDENITE ,INFRARED spectroscopy - Abstract
Natural purified mordenite from Palmarito de Cauto (ZP) deposit, Cuba, was subjected to a hydrothermal ion exchange process in acid medium with Fe
2+ or Fe3+ salts (Fe2+ ZP and Fe3+ ZP). The set of samples was characterized regarding their textural properties, morphology, and crystallinity, and tested in the NO reduction with CO/C3 H6 . Infrared spectroscopy coupled with NO as a probe molecule was used to give a qualitative description of the Fe species' nature and distribution. The exchange process caused an increase in the iron loading of the samples and a redistribution, resulting in more dispersed Fe2+ and Fe3+ species. When contacted with the NO probe, Fe2+ ZP showed the highest intensity of nitrosyl bands, assigned to NO adducts on isolated/highly dispersed Fe2+ /Fe3+ extra-framework sites and Fex Oy clusters. This sample is also characterized by the highest NO sorption capacity and activity in NO reduction. Fe3+ ZP showed a higher intensity of nitrosonium (NO+ ) species, without a correlation to NO storage and conversion, pointing to the reactivity of small Fex Oy aggregates in providing oxygen atoms for the NO to NO+ reaction. The same sites are proposed to be responsible for the higher production of CO2 observed on this sample, and thus to be detrimental to the activity in NO SCR. [ABSTRACT FROM AUTHOR]- Published
- 2019
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