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Skorynina A, Tereshchenko A, Usoltsev O, Bugaev A, Lomachenko K, Guda A, Groppo E, Pellegrini R, Lamberti C, Soldatov A. Time-dependent carbide phase formation in palladium nanoparticles. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2018.11.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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2
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Groppo E, Bonino F, Cesano F, Damin A, Manzoli M. CHAPTER 4. Raman, IR and INS Characterization of Functionalized Carbon Materials. Metal-free Functionalized Carbons in Catalysis 2018. [DOI: 10.1039/9781788013116-00103] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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3
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Carosso M, Lazzarini A, Piovano A, Pellegrini R, Morandi S, Manzoli M, Vitillo JG, Ruiz MJ, Lamberti C, Groppo E. Looking for the active hydrogen species in a 5 wt% Pt/C catalyst: a challenge for inelastic neutron scattering. Faraday Discuss 2018; 208:227-242. [DOI: 10.1039/c7fd00214a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We looked at the active hydrogen species in a highly dispersed and very homogeneous 5 wt% Pt/C industrial catalyst (Pt particle mean diameter of 2.0 ± 0.5 nm) for hydrogenation reactions, by coupling H2 adsorption measurements with Inelastic Neutron Scattering (INS).
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Affiliation(s)
- M. Carosso
- Department of Chemistry
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
| | - A. Lazzarini
- Department of Chemistry
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
| | - A. Piovano
- Institut Laue-Langevin (ILL)
- 38000 Grenoble
- France
| | | | - S. Morandi
- Department of Chemistry
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
| | - M. Manzoli
- Department of Drug Science and Technology
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
| | - J. G. Vitillo
- Department of Chemistry
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
| | | | - C. Lamberti
- Department of Physics and CrisDi Interdepartmental Centre
- University of Turin
- 10125 Turin
- Italy
- RC “Smart Materials”
| | - E. Groppo
- Department of Chemistry
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
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4
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Ganjkhanlou Y, Berlier G, Groppo E, Borfecchia E, Bordiga S. In Situ Investigation of the Deactivation Mechanism in Ni-ZSM5 During Ethylene Oligomerization. Top Catal 2017. [DOI: 10.1007/s11244-017-0845-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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5
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Lazzarini A, Pellegrini R, Piovano A, Rudić S, Castan-Guerrero C, Torelli P, Chierotti MR, Gobetto R, Lamberti C, Groppo E. The effect of surface chemistry on the performances of Pd-based catalysts supported on activated carbons. Catal Sci Technol 2017. [DOI: 10.1039/c7cy01005b] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work we investigated in detail the effects of nitric acid on the surface chemistry of two carbons, activated by steam and by phosphoric acid, meant to identify the nature and the concentration of the oxidized surface species.
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Affiliation(s)
- A. Lazzarini
- Department of Chemistry
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
| | - R. Pellegrini
- Chimet SpA – Catalyst Division
- Viciomaggio Arezzo
- Italy
| | - A. Piovano
- Institut Laue-Langevin (ILL)
- 38000 Grenoble
- France
| | - S. Rudić
- ISIS Facility
- Rutherford Appleton Laboratory
- Didcot
- UK
| | - C. Castan-Guerrero
- CNR-Istituto Officina dei Materiali
- Laboratorio TASC in Area Science Park
- 34149 Trieste
- Italy
| | - P. Torelli
- CNR-Istituto Officina dei Materiali
- Laboratorio TASC in Area Science Park
- 34149 Trieste
- Italy
| | - M. R. Chierotti
- Department of Chemistry
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
| | - R. Gobetto
- Department of Chemistry
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
| | - C. Lamberti
- Department of Chemistry
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
| | - E. Groppo
- Department of Chemistry
- NIS Centre and INSTM
- University of Turin
- Turin
- Italy
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6
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Botavina M, Barzan C, Piovano A, Braglia L, Agostini G, Martra G, Groppo E. Insights into Cr/SiO2 catalysts during dehydrogenation of propane: an operando XAS investigation. Catal Sci Technol 2017. [DOI: 10.1039/c7cy00142h] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In situ and operando XAS spectroscopic methods were applied to monitor the variations in the oxidation state and in the local structure of the chromium sites in a 2.0Cr/SiO2-DHS catalyst during propane dehydrogenation under non-oxidative and different oxidative conditions.
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Affiliation(s)
- M. Botavina
- Department of Chemistry, NIS and INSTM Reference Centre
- University of Turin
- 1-10135 Torino
- Italy
| | - C. Barzan
- Department of Chemistry, NIS and INSTM Reference Centre
- University of Turin
- 1-10135 Torino
- Italy
| | - A. Piovano
- Department of Chemistry, NIS and INSTM Reference Centre
- University of Turin
- 1-10135 Torino
- Italy
| | - L. Braglia
- Department of Chemistry, NIS and INSTM Reference Centre
- University of Turin
- 1-10135 Torino
- Italy
- European Synchrotron Radiation Facility (ESRF)
| | - G. Agostini
- IRC “Smart Materials”
- Southern Federal University
- 344090 Rostov-on-Don
- Russia
| | - G. Martra
- Department of Chemistry, NIS and INSTM Reference Centre
- University of Turin
- 1-10135 Torino
- Italy
- STM-CNR
| | - E. Groppo
- Department of Chemistry, NIS and INSTM Reference Centre
- University of Turin
- 1-10135 Torino
- Italy
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Botavina MA, Agafonov YA, Gaidai NA, Groppo E, Cortés Corberán V, Lapidus AL, Martra G. Towards efficient catalysts for the oxidative dehydrogenation of propane in the presence of CO2: Cr/SiO2 systems prepared by direct hydrothermal synthesis. Catal Sci Technol 2016. [DOI: 10.1039/c5cy00998g] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
CrOx/SiO2 catalysts with high propene/olefin yield, stable towards irreversible deactivation, are proposed for the oxidative dehydrogenation of propane with CO2.
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Affiliation(s)
- M. A. Botavina
- Department of Chemistry and “Nanostructured Interfaces and Surfaces – NIS” Interdepartmental Centre
- Torino, University of Torino
- Italy
| | - Yu. A. Agafonov
- N.D. Zelinsky Institute of Organic Chemistry
- Russ. Acad. Sci
- 117991 Moscow
- Russia
| | - N. A. Gaidai
- N.D. Zelinsky Institute of Organic Chemistry
- Russ. Acad. Sci
- 117991 Moscow
- Russia
| | - E. Groppo
- Department of Chemistry and “Nanostructured Interfaces and Surfaces – NIS” Interdepartmental Centre
- Torino, University of Torino
- Italy
| | | | - A. L. Lapidus
- N.D. Zelinsky Institute of Organic Chemistry
- Russ. Acad. Sci
- 117991 Moscow
- Russia
| | - G. Martra
- Department of Chemistry and “Nanostructured Interfaces and Surfaces – NIS” Interdepartmental Centre
- Torino, University of Torino
- Italy
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Lazzarini A, Piovano A, Pellegrini R, Leofanti G, Agostini G, Rudić S, Chierotti MR, Gobetto R, Battiato A, Spoto G, Zecchina A, Lamberti C, Groppo E. A comprehensive approach to investigate the structural and surface properties of activated carbons and related Pd-based catalysts. Catal Sci Technol 2016. [DOI: 10.1039/c6cy00159a] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Activated carbons and related Pd-based catalysts are investigated with a multi-techniques approach, which allows correlating structure and performance.
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Fainardi E, Bortolotti D, Bolzani S, Castellazzi M, Tamborino C, Roversi G, Baldi E, Caniatti ML, Casetta I, Gentili V, Granieri E, Rizzo R, Granieri E, Castellazzi M, Casetta I, Tola MR, Fainardi E, Dallocchio F, Bellini T, Rizzo R, Rotola A, Di Luca D, Seraceni S, Contini C, Sabbioni S, Negrini M, Tognon M, Antonelli T, Groppo E, Gentile M, Baldi E, Caniatti ML, Ceruti S, Manfrinato MR, Trentini A, Bortolotti D, Miotto E, Ferracin M, Mazzoni E, Pietrobon S, Masini I, Rotondo JC, Martini F, Baruzzi A, Roberto D’Alessandro R, Michelucci R, Salvi F, Stecchi S, Scandellari C, Terzano G, Granella F, Nichelli P, Sola P, Ferraro D, Vitetta F, Simone AM, Bedin R, Marcello N, Motti L, Montepietra S, Guidetti D, Immovilli P, Montanari E, Pesci I, Guareschi A, Greco G, Santangelo M, Mauro AM, Malagù S, Rasi F, Spadoni M, Galeotti M, Fiorani L, Neri W, Ravasio A, Pasquinelli M, Gutman S, Monaldini C. Cerebrospinal fluid amounts of HLA-G in dimeric form are strongly associated to patients with MRI inactive multiple sclerosis. Mult Scler 2015; 22:245-9. [DOI: 10.1177/1352458515590647] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/13/2015] [Indexed: 11/15/2022]
Abstract
Background: The relevance of human leukocyte antigen (HLA)-G in dimeric form in multiple sclerosis (MS) is still unknown. Objective: To investigate the contribution of cerebrospinal fluid (CSF) HLA-G dimers in MS pathogenesis. Methods: CSF amounts of 78-kDa HLA-G dimers were measured by western blot analysis in 80 MS relapsing–remitting MS (RRMS) patients and in 81 inflammatory and 70 non-inflammatory controls. Results: CSF amounts of 78kDa HLA-G dimers were more frequent in RRMS than in inflammatory ( p<0.01) and non-inflammatory controls ( p<0.001) and in magnetic resonance imaging (MRI) inactive than in MRI active RRMS ( p<0.00001). Conclusion: Our findings suggest that HLA-G dimers may be implicated in termination of inflammatory response occurring in MS.
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Affiliation(s)
- Enrico Fainardi
- Department of Neurosciences and Rehabilitation, Neuroradilogy Unit, Azienda Ospedaliero-Universitaria, Arcispedale S. Anna, Ferrara, Italy
| | - Daria Bortolotti
- Department of Medical Sciences, Section of Microbiology and Medical Genetics, University of Ferrara, Ferrara, Italy
| | - Silvia Bolzani
- Department of Medical Sciences, Section of Microbiology and Medical Genetics, University of Ferrara, Ferrara, Italy
| | - Massimiliano Castellazzi
- Department of Biomedical and Specialist Surgical Sciences, Section of Neurology, University of Ferrara, Ferrara, Italy
| | - Carmine Tamborino
- Department of Biomedical and Specialist Surgical Sciences, Section of Neurology, University of Ferrara, Ferrara, Italy
| | - Gloria Roversi
- Department of Biomedical and Specialist Surgical Sciences, Section of Neurology, University of Ferrara, Ferrara, Italy
| | - Eleonora Baldi
- Department of Neurosciences and Rehabilitation, Neurology Unit, Azienda Ospedaliero-Universitaria, Arcispedale S. Anna, Ferrara, Italy
| | - Maria Luisa Caniatti
- Department of Neurosciences and Rehabilitation, Neurology Unit, Azienda Ospedaliero-Universitaria, Arcispedale S. Anna, Ferrara, Italy
| | - Ilaria Casetta
- Department of Biomedical and Specialist Surgical Sciences, Section of Neurology, University of Ferrara, Ferrara, Italy
| | - Valentina Gentili
- Department of Medical Sciences, Section of Microbiology and Medical Genetics, University of Ferrara, Ferrara, Italy
| | - Enrico Granieri
- Department of Biomedical and Specialist Surgical Sciences, Section of Neurology, University of Ferrara, Ferrara, Italy
| | - Roberta Rizzo
- Department of Medical Sciences, Section of Microbiology and Medical Genetics, University of Ferrara, Ferrara, Italy
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Pellegrini R, Agostini G, Groppo E, Piovano A, Leofanti G, Lamberti C. 0.5wt.% Pd/C catalyst for purification of terephthalic acid: Irreversible deactivation in industrial plants. J Catal 2011. [DOI: 10.1016/j.jcat.2011.03.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Casetta I, Groppo E, De Gennaro R, Cesnik E, Piccolo L, Volpato S, Granieri E. Myasthenia gravis: a changing pattern of incidence. J Neurol 2010; 257:2015-9. [PMID: 20623298 DOI: 10.1007/s00415-010-5651-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Revised: 06/25/2010] [Accepted: 06/29/2010] [Indexed: 11/25/2022]
Abstract
The annual incidence of myasthenia gravis (MG) ranges from 3 to 30 per 1,000,000 people. Since the mid-1980s, an increasing incidence has been reported, mainly due to late-onset MG. Whether the increase was due to population aging, improved diagnosis and case collection, or a true excess of incidence cases is still under debate. We used a complete enumeration approach by reviewing all possible sources of case collection in the province of Ferrara, Italy, to estimate the MG incidence and its temporal trend over the study period (1985-2007). The mean annual age-adjusted incidence of MG was 18 per 1,000,000, without any significant temporal trend. The incidence rates in the period 1985-1990 were 14 both for early and late-onset MG. Thereafter, a significant increase in incidence of late-onset MG (p < 0.05), and a decrease in early onset MG were detected (p < 0.01). These findings were related to nonthymoma MG. The median age at onset of the disease steadily increased over time. A changing pattern of MG incidence with an increase in frequency of late-onset and a decrease of early onset MG was found in the last years, giving a significant shift to older age at onset of the disease. Unknown environmental factors may have driven this change in MG epidemiology.
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Affiliation(s)
- I Casetta
- Section of Clinical Neurology, Department of Medical and Surgical Sciences of Communication and Behavior, Neuroscience Center, University of Ferrara, Corso della Giovecca 203, 44100, Ferrara, Italy.
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12
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Pellegrini R, Leofanti G, Agostini G, Groppo E, Rivallan M, Lamberti C. Pd-supported catalysts: evolution of support porous texture along Pd deposition and alkali-metal doping. Langmuir 2009; 25:6476-6485. [PMID: 19348495 DOI: 10.1021/la900084p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Adsorption of N2 at 77 K and scanning electron microscopy have been used to measure the changes in the support morphology, at nano- and microscale level, along the processes involved in the preparation of a supported Pd catalyst: Pd deposition, doping, and thermal treatments. Among the investigated supports, viz., activated carbons, gamma-Al2O3, SiO2, and SiO2-Al2O3 (SA), the SA one was found particularly sensitive to these processes, as a result of its high plasticity and reactivity. Involved processes can be summarized as follows: (i) During the Pd deposition, the support itself is partially dissolved and removed as a result of both the basicity of the precipitating agent and the final washing. (ii) When the undoped sample is thermally treated up to 823 K, only modest phenomena are observed. (iii) Upon doping with potassium carbonate, the support dissolution continues, and the greater the carbonate concentration, the greater the dissolution extent. In this case the dissolved material is not removed, but reprecipitates (partially outside the pores), during the subsequent drying at 393 K. (iv) When doped samples are thermally treated, the reaction between carbonate and support causes the mobilization of the support itself, with sintering phenomena that can reach the total collapse of the porous structure. The starting temperature of the pore collapse decreases with increasing potassium carbonate concentration. The modification of the support influences, directly or indirectly, the surface properties and the availability of Pd particles that can be doped or even covered by materials from support and made more or less accessible or even inaccessible by pore narrowing, widening, or blocking.
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Affiliation(s)
- R Pellegrini
- Chimet S.p.A-Catalyst Division, Via di Pescaiola 74, I-52041 Viciomaggio, Arezzo, Italy.
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Groppo E, Estephane J, Lamberti C, Spoto G, Zecchina A. Ethylene, propylene and ethylene oxide in situ polymerization on the Cr(II)/SiO2 system: A temperature- and pressure-dependent investigation. Catal Today 2007. [DOI: 10.1016/j.cattod.2007.01.052] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bordiga S, Regli L, Bonino F, Groppo E, Lamberti C, Xiao B, Wheatley PS, Morris RE, Zecchina A. Adsorption properties of HKUST-1 toward hydrogen and other small molecules monitored by IR. Phys Chem Chem Phys 2007; 9:2676-85. [PMID: 17627311 DOI: 10.1039/b703643d] [Citation(s) in RCA: 320] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Among microporous systems metal organic frameworks are considered promising materials for molecular adsorption. In this contribution infrared spectroscopy is successfully applied to highlight the positive role played by coordinatively unsaturated Cu2+ ions in HKUST-1, acting as specific interaction sites. A properly activated material, obtained after solvent removal, is characterized by a high fraction of coordinatively unsaturated Cu2+ ions acting as preferential adsorption sites that show specific activities towards some of the most common gaseous species (NO, CO2, CO, N2 and H2). From a temperature dependent IR study, it has been estimated that the H2 adsorption energy is as high as 10 kJ mol(-1). A very complex spectral evolution has been observed upon lowering the temperature. A further peculiarity of this material is the fact that it promotes ortho-para conversion of the adsorbed H2 species.
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Affiliation(s)
- S Bordiga
- Dipartimento di Chimica IFM and NIS Centre of Excellence, Università di Torino, INSTM UdR Torino, Via Pietro Giuria 7, 10125, Torino, Italy.
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15
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Bertarione S, Prestipino C, Groppo E, Scarano D, Spoto G, Zecchina A, Pellegrini R, Leofanti G, Lamberti C. Direct IR observation of vibrational properties of carbonyl species formed on Pd nano-particles supported on amorphous carbon: comparison with Pd/SiO2–Al2O3. Phys Chem Chem Phys 2006; 8:3676-81. [PMID: 16883397 DOI: 10.1039/b606431k] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
By diluting optically opaque carbon-supported Pd particles in silica Aerosil we succeeded in observing the IR bands of adsorbed carbonyls and extracting information on the particle dispersion. Comparison with literature single crystal data and with silica-alumina supported Pd allowed us to make an assignment in terms of linear and 2-fold bridged carbonyls formed on Pd(111) and Pd(100) faces. Two Pd/C samples have been investigated. The relative intensities of the two carbonyl families observed on the two samples are consistent with the Pd dispersion independently measured with CO chemisorption, TEM and EXAFS analysis.
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Affiliation(s)
- S Bertarione
- Dipartimento di Chimica IFM, NIS Centre of Excellence and INSTM (Centro di Riferimento), Università di Torino, Via P. Giuria 7, I-10125-Torino, Italy
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16
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Groppo E, Lamberti C, Cesano F, Zecchina A. On the fraction of CrII sites involved in the C2H4 polymerization on the Cr/SiO2 Phillips catalyst: a quantification by FTIR spectroscopy. Phys Chem Chem Phys 2006; 8:2453-6. [PMID: 16721428 DOI: 10.1039/b604515d] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An estimation of the fraction of Cr(II) sites involved in the C(2)H(4) polymerization on a Cr(II)/SiO(2) Phillips catalyst has been obtained by means of in situ alternated CO adsorption and C(2)H(4) polymerization FTIR experiments: about 28% of the total surface sites react fast with C(2)H(4), while a lower fraction, which depends upon the temperature reaction conditions, is more slowly involved, in agreement with XANES results.
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Affiliation(s)
- E Groppo
- Department of Inorganic, Physical and Materials Chemistry, INSTM centro di riferimento and NIS Centre of Excellence, University of Turin, Torino, Italy.
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17
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Groppo E, Lamberti C, Bordiga S, Spoto G, Damin A, Zecchina A. FTIR Investigation of the H2, N2, and C2H4 Molecular Complexes Formed on the Cr(II) Sites in the Phillips Catalyst: a Preliminary Step in the understanding of a Complex System. J Phys Chem B 2005; 109:15024-31. [PMID: 16852901 DOI: 10.1021/jp051826w] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This work reports the first complete FTIR characterization of H2, N2 and C2H4 molecular complexes formed on the Cr(II) sites in the Phillips catalyst. The use of a silica aerogel as support for Cr(II) sites, substituting the conventional aerosil material, allowed us to obtain a remarkable increase in the signal-to-noise ratio of the IR spectra of adsorbed species. The improvement is directly related to an increase of the surface area of the support (approximately 700 m2 g(-1)) and to an almost complete absence of scattering [Groppo et al., Chem. Mater. 2005, 17, 2019-2027]. The use of this support and the adoption of suitable experimental conditions results, for the first time, in the clear observation of H2 and N2 adducts formed on two different types of Cr(II) sites, thus yielding important information on the coordinative state of the Cr(II) ions, which well agrees with the evidences provided in the past by other probe molecules. Furthermore, we report the first complete characterization of the C2H4 pi-complexes formed on Cr(II) sites. These results are particularly important in the view of the understanding of the polymerization mechanism, since the C2H4 coordination and the formation of pi-bonded complexes are the first steps of the reaction.
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Affiliation(s)
- E Groppo
- Department of Inorganic, Physical and Materials Chemistry, and NIS Center of Excellence, University of Torino, via P. Giuria 7, I-10125 Torino, Italy.
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Groppo E, Lamberti C, Bordiga S, Spoto G, Zecchina A. The Structure of Active Centers and the Ethylene Polymerization Mechanism on the Cr/SiO2 Catalyst: A Frontier for the Characterization Methods. Chem Rev 2005; 105:115-84. [PMID: 15720153 DOI: 10.1021/cr040083s] [Citation(s) in RCA: 354] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- E Groppo
- Department of Inorganic, Physical and Materials Chemistry and NIS Centre of Excellence, University of Torino, Via P. Giuria 7, 10125 Torino, Italy
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Groppo E, Prestipino C, Lamberti C, Luches P, Giovanardi C, Boscherini F. Growth of NiO on Ag(001): Atomic Environment, Strain, and Interface Relaxations Studied by Polarization Dependent Extended X-ray Absorption Fine Structure. J Phys Chem B 2003. [DOI: 10.1021/jp027788n] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | | | | | - F. Boscherini
- INFM and Dipartimento di Fisica, Università di Bologna, Viale C. Berti Pichat 6/2, 40127 Bologna, Italy
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