The CuCl2/Al2O3 Catalyst Investigated in Interaction with Reagents

Alumina supported CuCl2, the basic catalyst for ethylene oxychlorination, has been investigated by UV-Vis spectroscopy, EPR, EXAFS and XANES in a wide range (0.25-9.0 wt%) of Cu concentration. We have evidenced that, at low Cu content, the formation of a surface aluminate species takes place. The fo...

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Main Authors: Giuseppe Leofanti, Sandro Vidotto, Marco Garilli, Barbara Cremaschi, Andrea Marsella, Sofia Diaz Moreno, Giuseppe Spoto, Adriano Zecchina, Silvia Bordiga, Luciana Capello, Carmelo Prestipino, Carlo Lamberti
Format: Article
Language:English
Published: MDPI AG 2001-11-01
Series:International Journal of Molecular Sciences
Subjects:
EPR
Online Access:http://www.mdpi.com/1422-0067/2/5/230/
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spelling doaj-22fe486d13dc4ecebfed28549e52c6742020-11-24T21:44:30ZengMDPI AGInternational Journal of Molecular Sciences1422-00672001-11-012523024510.3390/i2050230The CuCl2/Al2O3 Catalyst Investigated in Interaction with ReagentsGiuseppe LeofantiSandro VidottoMarco GarilliBarbara CremaschiAndrea MarsellaSofia Diaz MorenoGiuseppe SpotoAdriano ZecchinaSilvia BordigaLuciana CapelloCarmelo PrestipinoCarlo LambertiAlumina supported CuCl2, the basic catalyst for ethylene oxychlorination, has been investigated by UV-Vis spectroscopy, EPR, EXAFS and XANES in a wide range (0.25-9.0 wt%) of Cu concentration. We have evidenced that, at low Cu content, the formation of a surface aluminate species takes place. The formation of this surface copper aluminate stops at 0.95 wt% Cu / 100 m2; at higher Cu concentrations excess copper chloride precipitates directly from solution during the drying step forming an highly dispersed CuCl2.H2O, phase, overlapping progressively the surface aluminate. Depletion tests and IR spectroscopy of adsorbed NO have demonstrated that the latter is the only active phase. A complete catalytic cycle has then been performed on CuCl2/Al2O3 catalyst. EPR, XANES and EXAFS, have been used to demonstrate that the ethylene oxychlorination reaction: C2H4 + 2HCl + ½ O2 --> C2H4Cl2 + H2O follows a three steps mechanism: (i) reduction of CuCl2 to CuCl (2CuCl2 + C2H4 --> C2H4Cl2 + 2CuCl), (ii) oxidation of CuCl to give an oxychloride (2CuCl + ½ O2 --> Cu2OCl2) and (iii) closure of the catalytic circle by rechlorination with HCl, restoring the original CuCl2 (Cu2OCl2 + 2HCl --> 2CuCl2 + H2O). Finally, we have shown that time resolved, in situ, spectroscopy is a very promising technique to investigate the interplay between catalyst activity and oxidation state of copper.http://www.mdpi.com/1422-0067/2/5/230/Al2O3 supported CuCl2ethylene oxychlorinationEPRXANESEXAFS
collection DOAJ
language English
format Article
sources DOAJ
author Giuseppe Leofanti
Sandro Vidotto
Marco Garilli
Barbara Cremaschi
Andrea Marsella
Sofia Diaz Moreno
Giuseppe Spoto
Adriano Zecchina
Silvia Bordiga
Luciana Capello
Carmelo Prestipino
Carlo Lamberti
spellingShingle Giuseppe Leofanti
Sandro Vidotto
Marco Garilli
Barbara Cremaschi
Andrea Marsella
Sofia Diaz Moreno
Giuseppe Spoto
Adriano Zecchina
Silvia Bordiga
Luciana Capello
Carmelo Prestipino
Carlo Lamberti
The CuCl2/Al2O3 Catalyst Investigated in Interaction with Reagents
International Journal of Molecular Sciences
Al2O3 supported CuCl2
ethylene oxychlorination
EPR
XANES
EXAFS
author_facet Giuseppe Leofanti
Sandro Vidotto
Marco Garilli
Barbara Cremaschi
Andrea Marsella
Sofia Diaz Moreno
Giuseppe Spoto
Adriano Zecchina
Silvia Bordiga
Luciana Capello
Carmelo Prestipino
Carlo Lamberti
author_sort Giuseppe Leofanti
title The CuCl2/Al2O3 Catalyst Investigated in Interaction with Reagents
title_short The CuCl2/Al2O3 Catalyst Investigated in Interaction with Reagents
title_full The CuCl2/Al2O3 Catalyst Investigated in Interaction with Reagents
title_fullStr The CuCl2/Al2O3 Catalyst Investigated in Interaction with Reagents
title_full_unstemmed The CuCl2/Al2O3 Catalyst Investigated in Interaction with Reagents
title_sort cucl2/al2o3 catalyst investigated in interaction with reagents
publisher MDPI AG
series International Journal of Molecular Sciences
issn 1422-0067
publishDate 2001-11-01
description Alumina supported CuCl2, the basic catalyst for ethylene oxychlorination, has been investigated by UV-Vis spectroscopy, EPR, EXAFS and XANES in a wide range (0.25-9.0 wt%) of Cu concentration. We have evidenced that, at low Cu content, the formation of a surface aluminate species takes place. The formation of this surface copper aluminate stops at 0.95 wt% Cu / 100 m2; at higher Cu concentrations excess copper chloride precipitates directly from solution during the drying step forming an highly dispersed CuCl2.H2O, phase, overlapping progressively the surface aluminate. Depletion tests and IR spectroscopy of adsorbed NO have demonstrated that the latter is the only active phase. A complete catalytic cycle has then been performed on CuCl2/Al2O3 catalyst. EPR, XANES and EXAFS, have been used to demonstrate that the ethylene oxychlorination reaction: C2H4 + 2HCl + ½ O2 --> C2H4Cl2 + H2O follows a three steps mechanism: (i) reduction of CuCl2 to CuCl (2CuCl2 + C2H4 --> C2H4Cl2 + 2CuCl), (ii) oxidation of CuCl to give an oxychloride (2CuCl + ½ O2 --> Cu2OCl2) and (iii) closure of the catalytic circle by rechlorination with HCl, restoring the original CuCl2 (Cu2OCl2 + 2HCl --> 2CuCl2 + H2O). Finally, we have shown that time resolved, in situ, spectroscopy is a very promising technique to investigate the interplay between catalyst activity and oxidation state of copper.
topic Al2O3 supported CuCl2
ethylene oxychlorination
EPR
XANES
EXAFS
url http://www.mdpi.com/1422-0067/2/5/230/
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