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A combined in situ XAS-XRPD-Raman study of Fischer–Tropsch synthesis over a carbon supported Co catalyst

Paper ID Volume ID Publish Year Pages File Format Full-Text
54932 47032 2013 8 PDF Available
Title
A combined in situ XAS-XRPD-Raman study of Fischer–Tropsch synthesis over a carbon supported Co catalyst
Abstract

A cobalt based Fischer–Tropsch synthesis (FTS) catalyst, supported on a carbon nanofibers/carbon felt composite (Co/CNF/CF) was studied in situ at realistic conditions. The catalyst was monitored by X-ray absorption spectroscopy (XAS), high-resolution X-ray powder diffraction (HR-XRPD) and Raman spectroscopy, while changes in the gas phase were observed by mass spectrometry (MS). Transmission electron microscopy (TEM) was also applied to characterise the catalyst. The catalyst has a bimodal particle size distribution and exhibits a high deactivation rate. During the in situ study the catalyst appears to reduce further at the induction period of FTS, while crystallite growth is been detected in the same period. At steady state FTS the amount of metallic Co is constant. A change in the volumetric flow towards higher conversions did not affect the degree of reduction or the crystallite size of the catalyst. Post-treatment at 400 °C under H2 atmosphere leads to sintering of the cobalt particles, while a CO treatment followed by H2 treatment creates a catalyst rich in hexagonal close packed cobalt through the formation of a Co2C intermediate.

Graphical abstract2D contour plot from the first derivatives of XANES spectra obtained throughout the experiment. Catalyst reduction, Fischer–Tropsch synthesis and post-treatments with H2 and CO are shown.Figure optionsDownload full-size imageDownload high-quality image (171 K)Download as PowerPoint slideHighlights► A structured Co/CNF/CF felt composite catalyst was studied in situ at relevant FTS conditions. ► A multi-technique approach was used combining in situ XAS, XRPD and Raman spectroscopy and ex situ TEM. ► XRPD and TEM analysis detected two phases of Co having different particle size, unit-cell parameters and reduction rate. ► At 18 bar and 215 °C for low-GHSV and high-GHSV no changes in the DOR and the average crystallite size could be observed. ► H2 treatment at 400 °C led to Co crystallite growth, while a CO-H2 treatment produce a hcp rich catalyst.

Keywords
Fischer–Tropsch synthesis; Cobalt; In situ; XRPD; XAS; Raman; TEM; Operando; CNF
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A combined in situ XAS-XRPD-Raman study of Fischer–Tropsch synthesis over a carbon supported Co catalyst
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 205, 30 April 2013, Pages 86–93
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