Study of the nature and location of silver in Ag-exchanged mordenite catalysts: characterization by spectroscopic techniques

Catalysts based on Na-mordenite (symbolized as M) exchanged with 5, 10, and 15 wt % of Ag were characterized by X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine line structure (EXAFS), X-ray absorption near edge spectroscopy (XANES) and UV-vis diffuse reflectance spectroscopy (...

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Detalles Bibliográficos
Autores principales: Aspromonte, Soledad Guadalupe, Mizrahi, Martín D., Schneeberger, Florencia A., Ramallo López, José Martín, Boix, Alicia Viviana
Formato: Articulo Preprint
Lenguaje:Inglés
Publicado: 2013
Materias:
Física
Química
Silver-exchanged mordenite
EXAFS-XANES
XPS
UV-Vis DRS
Auger parameter
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/102248
https://ri.conicet.gov.ar/11336/5312
http://pubs.acs.org/doi/abs/10.1021/jp4046269
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-102248
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Física
Química
Silver-exchanged mordenite
EXAFS-XANES
XPS
UV-Vis DRS
Auger parameter
spellingShingle Física
Química
Silver-exchanged mordenite
EXAFS-XANES
XPS
UV-Vis DRS
Auger parameter
Aspromonte, Soledad Guadalupe
Mizrahi, Martín D.
Schneeberger, Florencia A.
Ramallo López, José Martín
Boix, Alicia Viviana
Study of the nature and location of silver in Ag-exchanged mordenite catalysts: characterization by spectroscopic techniques
topic_facet Física
Química
Silver-exchanged mordenite
EXAFS-XANES
XPS
UV-Vis DRS
Auger parameter
description Catalysts based on Na-mordenite (symbolized as M) exchanged with 5, 10, and 15 wt % of Ag were characterized by X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine line structure (EXAFS), X-ray absorption near edge spectroscopy (XANES) and UV-vis diffuse reflectance spectroscopy (DRS) to investigate the effect of different treatments on the chemical state and surface concentration of the silver species. The AgxM catalysts were analyzed in oxidizing (O2) or reducing (H2/Ar) atmospheres and also after being used in the selective catalytic reduction of NOx or in successive cycles of toluene adsorption/desorption. In calcined samples, EXAFS profiles showed two types of AgO spheres of coordination, one due to a dispersed phase of silver oxide and the other due to Ag+ ions in interaction with the oxygen of the zeolite framework. The UV-vis DRS spectra showed the coexistence of isolated Ag+, Agn(delta)+ (n < 10) cationic clusters and AgxO particles. In addition, through the modified Auger parameter (alpha), calculated from XPS measurements, it was possible to identify Ag+ ions at exchange sites (alpha = 722 eV) and AgxO ( alpha = 725 eV) highly dispersed on the surface. Both species constitute stable active centers for the selective catalytic reduction of NOx under severe reaction conditions. However, during the adsorption-desorption of toluene, the reduction of silver oxides produces Ag(0) due to thermal hydrocarbon decomposition.
format Articulo
Preprint
author Aspromonte, Soledad Guadalupe
Mizrahi, Martín D.
Schneeberger, Florencia A.
Ramallo López, José Martín
Boix, Alicia Viviana
author_facet Aspromonte, Soledad Guadalupe
Mizrahi, Martín D.
Schneeberger, Florencia A.
Ramallo López, José Martín
Boix, Alicia Viviana
author_sort Aspromonte, Soledad Guadalupe
title Study of the nature and location of silver in Ag-exchanged mordenite catalysts: characterization by spectroscopic techniques
title_short Study of the nature and location of silver in Ag-exchanged mordenite catalysts: characterization by spectroscopic techniques
title_full Study of the nature and location of silver in Ag-exchanged mordenite catalysts: characterization by spectroscopic techniques
title_fullStr Study of the nature and location of silver in Ag-exchanged mordenite catalysts: characterization by spectroscopic techniques
title_full_unstemmed Study of the nature and location of silver in Ag-exchanged mordenite catalysts: characterization by spectroscopic techniques
title_sort study of the nature and location of silver in ag-exchanged mordenite catalysts: characterization by spectroscopic techniques
publishDate 2013
url http://sedici.unlp.edu.ar/handle/10915/102248
https://ri.conicet.gov.ar/11336/5312
http://pubs.acs.org/doi/abs/10.1021/jp4046269
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