Effect of Li Promoter on titania-supported Rh catalyst for ethanol formation from CO hydrogenation

The addition of 0.10 wt% Li to Rh/TiO 2 more than doubled the CO conversion for CO hydrogenation while increasing ethanol selectivity. The addition of Li also increases formation of C 2 oxygenates at the expense of C 1 species, methanol and methane. This is attributed to enhanced dispersion of Rh by...

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Bibliographic Details
Published in:Catalysis today 2010-01, Vol.149 (1), p.91-97
Main Authors: Egbebi, Adefemi, Schwartz, Viviane, Overbury, Steven H., Spivey, James J.
Format: Article
Language:English
Subjects:
03 NATURAL GAS
10 SYNTHETIC FUELS
ADSORPTION
AUGMENTATION
BONDING
CARBON MONOXIDE
Catalysis
CATALYSTS
CHEMISORPTION
Chemistry
CONVERSION
DISPERSIONS
DISSOCIATION
ETHANOL
Exact sciences and technology
General and physical chemistry
HYDROGENATION
LITHIUM
Lithium promoter
METHANE
METHANOL
PROMOTERS
RHODIUM
Rhodium catalyst
Surface physical chemistry
SURFACES
Syngas
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
Titania support
TITANIUM OXIDES
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Summary:The addition of 0.10 wt% Li to Rh/TiO 2 more than doubled the CO conversion for CO hydrogenation while increasing ethanol selectivity. The addition of Li also increases formation of C 2 oxygenates at the expense of C 1 species, methanol and methane. This is attributed to enhanced dispersion of Rh by Li that appears to reduce dissociation of CO, which previous studies have shown requires large ensembles of Rh atoms on the surface. Li promotion appears to increase the associatively adsorbed CO, allowing for increased H 2 chemisorption on the surface compared to the dissociative adsorption of the same number of CO atoms. This increases selectivity to ethanol compared to the unpromoted catalysts. CO-TPD shows more reactive adsorbed CO species on the Li-promoted catalyst. FTIR results suggest that Li promotion alters CO bonding at bridged or interfacial sites and its effect is more structural than electronic.
ISSN:0920-5861
1873-4308
DOI:10.1016/j.cattod.2009.07.104