We present a methodology that allows us to extract quantitative information from EXAFS data collected on complex samples where the absorbing species is present in more than one phase. We have chosen as our case study the CuCl2/Al2O3 material, which represents the basic catalyst for the ethylene oxychlorination reaction (a fundamental intermediate step in PVC production). In previous studies [J. Catal. 2000, 189, 91, and J. Catal. 2000, 189, 105], it has been shown that three different copper species are present on CuCl2/Al2O3-a Cu-aluminate phase, a highly dispersed copper chloride phase, and an aggregated paratacamite (Cu-2(OH)(3)Cl) phase, whose relative fraction depends on copper loading, sample aging, and heating conditions. In this work, we extract from the EXAFS spectra the fraction of the three phases on a quantitative ground. A study of the corresponding XANES spectra allows us to qualitatively support the EXAFS results. This methodology represents a generalization of the standard EXAFS procedure that can be of general interest in all cases where more than one phase is present on the sample.

Structural determination of copper species on the alumina-supported copper chloride catalyst: a detailed EXAFS study

PRESTIPINO, Carmelo;BORDIGA, Silvia;LAMBERTI, Carlo;FISICARO, Paola;SPOTO, Giuseppe;ZECCHINA, Adriano
2003-01-01

Abstract

We present a methodology that allows us to extract quantitative information from EXAFS data collected on complex samples where the absorbing species is present in more than one phase. We have chosen as our case study the CuCl2/Al2O3 material, which represents the basic catalyst for the ethylene oxychlorination reaction (a fundamental intermediate step in PVC production). In previous studies [J. Catal. 2000, 189, 91, and J. Catal. 2000, 189, 105], it has been shown that three different copper species are present on CuCl2/Al2O3-a Cu-aluminate phase, a highly dispersed copper chloride phase, and an aggregated paratacamite (Cu-2(OH)(3)Cl) phase, whose relative fraction depends on copper loading, sample aging, and heating conditions. In this work, we extract from the EXAFS spectra the fraction of the three phases on a quantitative ground. A study of the corresponding XANES spectra allows us to qualitatively support the EXAFS results. This methodology represents a generalization of the standard EXAFS procedure that can be of general interest in all cases where more than one phase is present on the sample.
2003
107
5022
5030
http://pubs.acs.org/doi/abs/10.1021/jp027507b
OXYCHLORINATION CATALYSTS; CUCL2; EXAFS SPECTROSCOPY; XANES SPECTROSCOPY; ETHYLENE OXYHYDROCHLORINATION; phase recignituion
C. PRESTIPINO; S. BORDIGA; C. LAMBERTI; S. VIDOTTO; M. GARILLI; B. CREMASCHI; A. MARSELLA; G. LEOFANTI; P. FISICARO; G. SPOTO; A. ZECCHINA
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/21382
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