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Influence of carbide formation on oxygenates selectivity during Fischer-Tropsch synthesis over Ce-containing Co catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
53381 46966 2016 8 PDF Available
Title
Influence of carbide formation on oxygenates selectivity during Fischer-Tropsch synthesis over Ce-containing Co catalysts
Abstract

•Ce0.75Si0.25O2 or Ce0.65Mn0.1Si0.25O2 were used as supports for Co FT synthesis.•Cobalt carbide was formed under the FT synthesis conditions selected.•Cobalt carbide formation enhances oxygenates selectivity.•The support plays an important role in controlling FT product selectivity of Co.

Fischer-Tropsch (FT) synthesis was performed over 15%Co/CeSi and 15Co/CeMnSi catalysts using a 1 L CSTR at 230 °C, 1.89 MPa and a H2/CO ratio of 1.86. The oxygenate selectivity for both catalysts increased with increasing time-on-stream during FT synthesis. X-ray diffraction, EXAFS and HR-TEM analyses of fresh catalysts and those withdrawn during FT synthesis indicate that increases in the selectivity for oxygenates with time are related to structural changes in the catalyst, most likely associated with a transition from a metallic cobalt surface to one containing surface cobalt carbide. Moreover, a significant effect of carburization on increasing the selectivity for oxygenates was observed for FTS using the 15Co/CeMnSi catalyst. The reactivity of CO was inhibited by the presence of carbon on the surface of cobalt which promoted oxygenate formation through a CO insertion mechanism.

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Keywords
Cobalt carbide; Fischer-Tropsch synthesis; Oxygenates selectivity; CO insertion mechanism; CeO2 support; EXAFS-XANES; HR-TEM
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Influence of carbide formation on oxygenates selectivity during Fischer-Tropsch synthesis over Ce-containing Co catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 261, 1 March 2016, Pages 40–47
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
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Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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