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Titolo:
The decomposition pathways of methanol on clean Ru(0001), studied by reflection-absorption infrared spectroscopy (RAIRS)
Autore:
Barros, RB; Garcia, AR; Ilharco, LM;
Indirizzi:
Inst Super Tecn, Ctr Quim Fis Mol, P-1049001 Lisbon, Portugal Inst Super Tecn Lisbon Portugal P-1049001 ol, P-1049001 Lisbon, Portugal
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 45, volume: 105, anno: 2001,
pagine: 11186 - 11193
SICI:
1520-6106(20011115)105:45<11186:TDPOMO>2.0.ZU;2-3
Fonte:
ISI
Lingua:
ENG
Soggetto:
ENERGY-LOSS SPECTROSCOPY; ADSORPTION; SURFACE; OXIDATION; METHOXY; FORMALDEHYDE; PLATINUM; CH3OH; PHASE; IDENTIFICATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
49
Recensione:
Indirizzi per estratti:
Indirizzo: Ilharco, LM Inst Super Tecn, Ctr Quim Fis Mol, Complexo 1,Av Rovisco Pais,P-1049001 Lisbon, Portugal Inst Super Tecn Complexo 1,Av Rovisco Pais Lisbon Portugal P-1049001
Citazione:
R.B. Barros et al., "The decomposition pathways of methanol on clean Ru(0001), studied by reflection-absorption infrared spectroscopy (RAIRS)", J PHYS CH B, 105(45), 2001, pp. 11186-11193

Abstract

The adsorption and decomposition of methanol on clean Ru(0001) were investigated by reflection-absorption infrared spectroscopy (RAIRS). At low temperature (90 K) and coverage (0.1 L), it was confirmed that methanol adsorbs dissociatively as methoxide (CH3O-). No experimental evidence was obtained of an alternative decomposition for high coverage. Different bonding sites and geometries, depending on temperature and coverage, were proposed for methoxide and correlated with the corresponding CO stretching wavenumbers. Methoxide may either undergo complete dehydrogenation into CO(ads) and H-(ads), if annealed in small temperature steps (in the range between 110 and 320K), or partial dehydrogenation into very stable eta (2)-formaldehyde, by aone-step thermal activation (from 130 K to at least 190 K), in the presence of previously formed products (CO and atomic species). At high temperatures (greater than or equal to 190 K), methanol undergoes O-H, C-H, and C-O bond scission, leaving surface fragments undetectable by RAIRS. However, in a sequential dosing, the fragments from the first methanol molecules that hit the surface seem to have a passivating effect on Ru(0001). Subsequent doses undergo only partial dehydrogenation, yielding eta (2)-formaldehyde, which was isolated on the surface in two bonding configurations: bridging [mu(2)-eta (2)(C,O)-H2CO] and chelating [mu (1)-eta (2)(C,O )-H2CO], characterized by the vCO mode at 1262 and 1277 cm(-1), respectively. This assignment was confirmed by adsorbing CD3OH. The bridging form is favored at lower coverage. Formaldehyde prepared by sequential dosing is stable on the surface up to at least 290 K, although some dehydrogenates to CO(ads) above 190 K.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 12:56:22