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Titolo:
Rh3+ and Rh3+-diamine complexes intercalated in gamma-titanium hydrogen phosphate. Synthesis, characterisation and catalytic activity towards anilineoxidative carbonylation processes
Autore:
Giannoccaro, P; De Giglio, E; Gargano, M; Aresta, M; Ferragina, C;
Indirizzi:
Univ Bari, CNR, Dipartimento Chim, I-70126 Bari, Italy Univ Bari Bari Italy I-70126 CNR, Dipartimento Chim, I-70126 Bari, Italy Univ Bari, CNR, Ctr MISO, I-70126 Bari, Italy Univ Bari Bari Italy I-70126 iv Bari, CNR, Ctr MISO, I-70126 Bari, Italy CNR, IMAI, Area Ric Roma, Rome, Italy CNR Rome ItalyCNR, IMAI, Area Ric Roma, Rome, Italy
Titolo Testata:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
fascicolo: 1-2, volume: 157, anno: 2000,
pagine: 131 - 141
SICI:
1381-1169(20000620)157:1-2<131:RARCII>2.0.ZU;2-E
Fonte:
ISI
Lingua:
ENG
Soggetto:
ALPHA-ZIRCONIUM PHOSPHATE; PILLARS; INSITU; AMINES; CO;
Keywords:
reductive carbonylation; carbamates; N,N '-diphenylurea; rhodium-supported; heterogeneous catalysis; titanium hydrogen phosphate; intercalation compounds;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
24
Recensione:
Indirizzi per estratti:
Indirizzo: Giannoccaro, P Univ Bari, CNR, Dipartimento Chim, Trav Re David, I-70126 Bari, Italy Univ Bari Trav Re David Bari Italy I-70126 126 Bari, Italy
Citazione:
P. Giannoccaro et al., "Rh3+ and Rh3+-diamine complexes intercalated in gamma-titanium hydrogen phosphate. Synthesis, characterisation and catalytic activity towards anilineoxidative carbonylation processes", J MOL CAT A, 157(1-2), 2000, pp. 131-141

Abstract

New materials containing Rh(III) ions or Rh(III)-diamine complexes [(L = 2,2'-bipyridyl (bipy); 1,10-phenanthroline (phen); 2,9-dimethyl-1,10-phenanthroline (dmp)] intercalated in gamma-titanium phosphate (gamma-TiP) are described. The compounds have formula gamma-TiPHxRhy. tH(2)O (x= 2-3y; 0 <y <0.18; 1.5 <t<2.2), hereafter indicated as gamma-TiPRh, and gamma-TiPHxRhyLz.nH(2)O (x = 2-3y; 0 < y < 0.25; 0 < z < 0.35; 2.5 < n < 4.2), hereafter indicated as gamma-TiPRhL. They were prepared by contacting samples of gamma-TiP and gamma-TiPL with appropriate volumes of Rh(III) solution, at 45 degrees C. The materials were characterised by X-ray diffraction pattern and TG-DTA techniques. Their catalytic activity towards aniline carbonylation wastested. The compounds catalyse the oxidative carbonylation of aniline to diphenylurea (DPU) and/or methylphenylcarbamate (MPC). When the reaction is carried out in methanol or CH3CN, at 70-90 degrees C under moderate pressure of a CO/O-2 mixture (P-tot = 0.5 divided by 5 MPa; P(O-2)= 0.1 divided by0.8 MPa),;aniline is converted to DPU with a yield of 90% with respect to CO. The catalysts recovered and reused do not show any decrease of activity. When more drastic temperature conditions (110-150 degrees C) are used, the carbonylation is not selective and the yield off carbon monoxide fixationis strongly dependent on the solvent. In CH3CN, aniline is converted into DPU with a selectivity of 90% and the yield of CO fixation is still high (85%). Conversely, in methanol, N-phenylmethylcarbamate (MPC) is the main product with relevant amounts of CO2 formed and a CO fixation yield not higherthan 70%. Under these conditions, the catalysts when reused have shown a decrease of activity. On the basis of XPS analysis, it has been ascertained that the decrease in activity is due to an irreversible reduction of Rh3+ to Rh-o that causes the release of the metal from the support and the consequent deactivation of the catalyst. (C) 2000 Elsevier Science B.V. All rights reserved.

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Documento generato il 28/09/20 alle ore 11:27:56