Infrared spectroscopic study of the adsorption and reactions of CO sub 2 on K-modified Rh/SiO sub 2

Journal Article · Thu Mar 01 00:00:00 EST 1990 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(90)90268-O· OSTI ID:6379394

Solymosi, F; Knoezinger, H ^[1]

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1. Universitaet Muenchen (West Germany)

Adsorption of CO{sub 2} on K-free Rh/SiO{sub 2} at 140 K produced only a strong band at 2,340 cm{sup {minus}1} characteristic of weakly bonded CO{sub 2}. There was no carbonate formation and CO{sub 2} desorbed completely from this surface below 250 K without any detectable dissociation. Co-adsorption of H{sub 2} + CO{sub 2} on Rh/SiO{sub 2} led to the formation of CO bands at 2,050 and 2,015 cm{sup {minus}1}, indicating the dissociation of CO{sub f2}. Formate bands were not observed. Adsorption of CO{sub 2} on K-modified Rh/SiO{sub 2} produced an intense band at 1,695-1,675 cm{sup {minus}1} and a weak band at 1,325-1,360 cm{sup {minus}1}, which are attributed to the formation of CO{sub 2}{sup {minus}} anions bonded to K{sup +} ions. Spectral changes observed above 200 K suggest that the species is transformed into bidentate carbonate characterized by absorption bands at 1,660, 1,525, and 1,360 cm{sup {minus}1}. As the same features were observed for Rh-free samples, it was concluded that both species are coordinated to K{sup +}-sites on the silica surface. CO{sub 2}{sup {minus}} reacted with hydrogen on (K + Rh)/SiO{sub 2} to give formate at temperatures as low as 150 K. No formate was produced on K/SiO{sub 2} in the absence of Rh.

• OSTI ID: 6379394
• Journal Information: Journal of Catalysis; (USA), Vol. 122:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
01 COAL, LIGNITE, AND PEAT
CARBON DIOXIDE
ADSORPTION
POTASSIUM
CATALYTIC EFFECTS
SORPTIVE PROPERTIES
RHODIUM
CARBON MONOXIDE
CARBONATES
CATALYST SUPPORTS
CHEMICAL REACTIONS
DISSOCIATION
FORMATES
HYDROGEN
INFRARED SPECTRA
SILICON OXIDES
SYNTHESIS
TEMPERATURE DEPENDENCE
ALKALI METALS
CARBON COMPOUNDS
CARBON OXIDES
CARBOXYLIC ACID SALTS
CHALCOGENIDES
ELEMENTS
METALS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
SILICON COMPOUNDS
SORPTION
SPECTRA
SURFACE PROPERTIES
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties
010408 - Coal
Lignite
& Peat- C1 Processes- (1987-)