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9. Ethylene, propylene and ethylene oxide in situ polymerization on the Cr(II)/SiO2 system: A temperature- and pressure-dependent investigation

Author

Groppo, E., Estephane, J., Lamberti, C., Spoto, G., and Zecchina, A.

Subjects
*POLYMERIZATION, *ALKENES, *ETHYLENE, *PROPENE
Abstract

Abstract: The Cr(II)/SiO2 system was found to be able to activate and polymerize at room temperature not only light olefins (such as ethylene and propylene), but also a cyclic molecule such as ethylene oxide, which does not contain a C–C unsaturation. The polymerization of ethylene, propylene and ethylene oxide on the Cr(II)/SiO2 system have been followed in situ by means of temperature- and pressure-resolved FTIR spectroscopy. This method allowed to “freeze” the precursors of the reaction and the intermediate species, even when their amount is low in comparison with spectator species, and in some cases to determine the initiation mechanism. Information about the energy barrier associated with the polymerization reaction (temperature at which the reaction starts) and about the kinetic of the process (time dependence of the experiment) have been obtained in the three cases. [Copyright &y& Elsevier]

Published
2007
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10. Formation and growth of palladium nanoparticles inside porous poly(4-vinyl-pyridine) monitored by operando techniques: The role of different reducing agents

Author

Giuseppe Portale, Alessandro Longo, Riccardo Pellegrini, Giovanni Agostini, Elisa Borfecchia, Francesco Giannici, Andrea Lazzarini, Elena Groppo, Carlo Lamberti, Macromolecular Chemistry & New Polymeric Materials, Lazzarini, A., Groppo, E., Agostini, G., Borfecchia, E., Giannici, F., Portale, G., Longo, A., Pellegrini, R., and Lamberti, C.

Subjects
inorganic chemicals, Reducing agent, Infrared spectroscopy, chemistry.chemical_element, 02 engineering and technology, Thermal treatment, 010402 general chemistry, Photochemistry, 01 natural sciences, AEROBIC ALCOHOL OXIDATION, Catalysis, Catalysi, P4VP, RUTHENIUM NANOPARTICLES, Molecule, Organic chemistry, Operando, CATALYTIC-ACTIVITY, chemistry.chemical_classification, PD NANOPARTICLES, DRIFT, Palladium nanoparticles, SAXS, XANES, Chemistry, IN-SITU, Chemistry (all), General Chemistry, Polymer, Palladium nanoparticle, SELECTIVE OXIDATION, 021001 nanoscience & nanotechnology, X-RAY-SCATTERING, PARTICLE-SIZE, 0104 chemical sciences, Colloidal gold, GOLD NANOPARTICLES, VIBRATIONAL PROPERTIES, 0210 nano-technology, Palladium
Abstract

In this work we followed the formation of palladium nanoparticles, starting from palladium (II) acetate precursor, inside a poly(4-vinylpyridine-co-divinylbenzene) polymer in presence of different reducing agents. The formation and growth of palladium nanoparticles in presence of H-2 was followed as a function of temperature by simultaneous XANES-SAXS techniques, coupled with DRIFT spectroscopy in operando conditions. It was found that the pyridyl functional groups in the polymer plays a fundamental role in the stabilization of the palladium (II) acetate precursor, as well as in the stabilization of the palladium nanoparticles. The effect of a thermal treatment in alcohol (ethanol and 2-propanol) was preliminarily investigated by means of DRIFT spectroscopy in operando conditions. We found that alcohols act as reducing agents for Pd(OAc)(2). The obtained palladium nanoparticles were preliminarily characterized by means of IR spectroscopy using CO as probe molecule. (C) 2016 Elsevier B.V. All rights reserved.

Published
2017
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