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Effect of water on the space-time yield of different supported cobalt catalysts during Fischer–Tropsch synthesis

Paper ID Volume ID Publish Year Pages File Format Full-Text
41747 45899 2011 13 PDF Available
Title
Effect of water on the space-time yield of different supported cobalt catalysts during Fischer–Tropsch synthesis
Abstract

The effect of partial pressure of water on the Fischer–Tropsch (FT) rate of six cobalt-based catalysts supported on three different carrier materials (γ-Al2O3, α-Al2O3, TiO2) with varying Co particle sizes was investigated in a fixed-bed reactor by changing space velocity and by external water vapour addition. A typical catalyst pellet size (<100 μm) for industrial slurry-bed FT reactors was used. Water was found to have a positive kinetic effect, at least up to moderate amounts, on the FT rate of all catalysts in the present study, including the γ-Al2O3-supported catalyst with pores smaller than ∼10 nm. The reason for the apparent negative effect on the space-time yield at a direct exposure of Co supported on narrow-pore γ-Al2O3 to high partial pressures of water is due to a rapid and extensive deactivation. This could be ascribed to formation of hard-to-reduce oxidized cobalt species. The choice of support material was found to have a major effect on the response to changes in partial pressure of water, both with respect to deactivation behaviour and kinetics. However, there is a minor Co-particle size effect on the magnitude of the kinetic effect of water, larger Co particles showing a more positive response. Different extents of mass transfer limitations and/or differences in fugacities of H2, CO and water among the six catalysts could be ruled out as causes for the observed differences.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (112 K)Download as PowerPoint slideResearch highlights▶ Positive kinetic effect of added water demonstrated for Co supported on TiO2 and Al2O3. ▶ Rapid and extensive deactivation of cobalt supported on narrow-pore alumina. ▶ Methane formation follows a rate expression different from the higher hydrocarbons.

Keywords
Fischer–Tropsch; Cobalt; Water; Deactivation; Particle size; Microemulsion
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Effect of water on the space-time yield of different supported cobalt catalysts during Fischer–Tropsch synthesis
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 393, Issues 1–2, 15 February 2011, Pages 109–121
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
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
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