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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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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