Generation and characterization of rhodium carbonyls formed on silica and alumina under mild conditions

Journal Article · Tue Mar 01 04:00:00 EST 1988 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(88)90300-4· OSTI ID:5287059

Keyes, M P; Watters, K L

The effect of the metal precursor on the surface structure of Rh supported on SiO/sub 2/ and Al/sub 2/O/sub 3/ was examined. Rh(I) on SiO/sub 2/ was obtained by sublimation of (Rh(CO)/sub 2/Cl)/sub 2/ and by mild reduction under CO of RhCl/sub 3/SiO/sub 2/ and of Rh(NO/sub 3/)/sub 3/SiO/sub 2/. In each case, three v(CO) IR bands were obtained with frequency and intensity patterns that closely matched those for molecular dirhodium complexes, indicating a dinuclear structure on the SiO/sub 2/ surface. Solvent extraction results led to the conclusion that if a dicarbonyl species was generated with Rh(NO/sub 3/)/sub 3/SiO/sub 2/ it was in the form (Rh(CO/sub 2/O/sub s/)/sub 2/ (where O/sub s/ is a surface oxide), while direct sublimation of (Rh(CO)/sub 2/Cl) onto SiO/sub 2/ and reduction of RhCl/sub 3/SiO/sub 2/ both formed physisorbed (Rh(CO)/sub 2/Cl)/sub 2/ that could be extracted readily from the surface into pentane. The (Rh(CO)/sub 2/Cl)/sub 2/ absorbed on pretreated Al/sub 2/O/sub 3/ behaved differently. Three v(CO) IR bands initially evident displayed a pattern different from that for the parent dirhodium complex. The weak band vanished within an hour while the two strong bands remained. The remaining bands were indistinguishable from the v(CO) bands reported for monomeric surface Rh/sup 1/(CO)/sub 2/ species derived from RhCl/sub 3/Al/sub 2/O/sub 3/ and Rh(NO/sub 3/)/sub 3/Al/sub 2/O/sub 3/, while the short-lived species identified with the weak band is proposed to be a monocarbonyl of Rh(I). Pretreatment of the Al/sub 2/O/sub 3/ at 800/sup 0/C produced a sample with shifted v(CO) bands and color much different from that for other samples studied. The formation of the proposed monocarbonyl and the different behavior after 800/sup 0/C pretreatment are discussed in terms of the role of Cl and Lewis acid sites

• Research Organization: Univ. of Wisconsin, Milwaukee (USA)
• OSTI ID: 5287059
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 110:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010408 -- Coal
Lignite
& Peat-- C1 Processes-- (1987-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON MONOXIDE
CARBON OXIDES
CARBONYLS
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL PROPERTIES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CRYSTAL STRUCTURE
EXTRACTION
HALIDES
HALOGEN COMPOUNDS
HYDROGENATION
INFRARED SPECTRA
MINERALS
NITRATES
NITROGEN COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
RHODIUM CHLORIDES
RHODIUM COMPOUNDS
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SOLVENT EXTRACTION
SPECTRA
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS