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Titolo:
Characterisation of catalysts and their precursors prepared from supportedpalladium phosphine complexes
Autore:
Cairns, GR; Cross, RJ; Stirling, D;
Indirizzi:
Univ Glasgow, Dept Chem, Glasgow G12 8QQ, Lanark, Scotland Univ Glasgow Glasgow Lanark Scotland G12 8QQ ow G12 8QQ, Lanark, Scotland
Titolo Testata:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
fascicolo: 1-2, volume: 172, anno: 2001,
pagine: 207 - 218
SICI:
1381-1169(20010705)172:1-2<207:COCATP>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
1ST EXAMPLE; HYDROGENATION; MONTMORILLONITE; INSERTION; BOND;
Keywords:
hydrogenation catalysts; palladium phosphine complexes; spectroscopy;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
29
Recensione:
Indirizzi per estratti:
Indirizzo: Stirling, D Univ Glasgow, Dept Chem, Glasgow G12 8QQ, Lanark, Scotland Univ Glasgow Glasgow Lanark Scotland G12 8QQ Lanark, Scotland
Citazione:
G.R. Cairns et al., "Characterisation of catalysts and their precursors prepared from supportedpalladium phosphine complexes", J MOL CAT A, 172(1-2), 2001, pp. 207-218

Abstract

Hydrogenation catalysts prepared from the silica-supported binuclear palladium complexes [Pd2X4(PR3)(2)] (X = Cl, Br or I, and R = Me, Et and, for X = Br only, Pr-i and Bu) and mononuclear complexes [PdX2(PR3)(2)] (X = Cl, Br or I, and R = Me, Et) have been examined throughout their life cycle (induction period, selectively active catalyst and deactivation) by XPS, solid state P-31 NMR spectroscopy and transmission electron microscopy, and theirperformance and activities compared to a simple Pd/SiO2 catalyst. The binuclear chloro complexes partially react with the silica surface producing some Pd(0) species. The others retain their integrity until contacted by the substrate and hydrogen. The selective solution hydrogenation of cinnamaldehyde to hydrocinnamaldehyde appeals to take place at oxidised palladium sites, most likely dipalladium(I) monophosphine species. The formation of phenylpropanol by some of the catalysts, on the other hand, occurs at Pd(0) sites. The induction period before the catalysts become active results from an autocatalytic process during which the Pd(II) precursors are converted to the active, Pd(I) or Pd(0) species. The catalysts are finally deactivated bya combination of continued conversion of the active species to a new, phosphorus-poisoned Pd(0) material and the restructuring of a hydrocarbonaceousoverlayer. (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 06/04/20 alle ore 08:03:54