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In situ characterization of the genesis of cobalt metal particles in silica-supported Fischer-Tropsch catalysts using Foner magnetic method

Paper ID Volume ID Publish Year Pages File Format Full-Text
44398 46024 2006 12 PDF Available
Title
In situ characterization of the genesis of cobalt metal particles in silica-supported Fischer-Tropsch catalysts using Foner magnetic method
Abstract

The genesis of cobalt metal particles in silica-supported Fischer-Tropsch catalysts was studied using in situ Foner vibrating-sample magnetic method. The cobalt promoted and unpromoted catalysts were prepared by aqueous (co)-impregnation using cobalt nitrate or acetate, ruthenium nitrosyl nitrate or perrhenic acid followed by oxidative pre-treatment in air and reduction in hydrogen. In several catalyst preparations, sucrose was added to the impregnating solutions.The genesis of cobalt metal phases in these catalysts was monitored in situ by the magnetic method during the temperature-programmed reduction in pure hydrogen. A considerably higher extent of cobalt reduction was found in the catalysts prepared from cobalt nitrate than in those prepared from cobalt acetate. Promotion with ruthenium and rhenium results in a considerable decrease in the temperature of the emergence of cobalt metal phases.Small superparamagnetic, single-domain and multi-domain ferromagnetic cobalt metal particles were observed in the reduced catalysts by the magnetic method. It was found that lower temperature calcination of the cobalt catalysts prepared from cobalt nitrate and addition of sucrose to the impregnating solution lead to a decrease in the concentration of multi-domain cobalt ferromagnetic metal particles and to an increase in the fraction of superparamagnetic cobalt particles. Superparamagnetic cobalt particles smaller than 6–7 nm were detected in the reduced catalysts prepared from cobalt nitrate with sucrose addition and in the catalysts prepared from cobalt acetate. Catalyst characterization using X-ray diffraction and X-ray photoelectron spectroscopy has confirmed the results about cobalt dispersion and reducibility in the cobalt silica-supported catalysts obtained by the Foner magnetic method.

Keywords
In situ; Catalyst characterization; Dynamic magnetic method; Foner vibrating-sample magnetometer; Fischer-Tropsch synthesis; Cobalt catalyst; Nanoparticles
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In situ characterization of the genesis of cobalt metal particles in silica-supported Fischer-Tropsch catalysts using Foner magnetic method
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 306, 7 June 2006, Pages 108–119
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
Any Questions? feel free to contact us