1 Department of Energy Conversion and Storage, Technical University of Denmark2 Atomic scale modelling and materials, Department of Energy Conversion and Storage, Technical University of Denmark3 Norwegian University of Science and Technology4 European Synchrotron Radiation Facility5 SINTEF6 Statoil ASA7 Norwegian University of Science and Technology8 European Synchrotron Radiation Facility9 Statoil ASA
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 Xray 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 degrees C under H-2 atmosphere leads to sintering of the cobalt particles, while a CO treatment followed by H-2 treatment creates a catalyst rich in hexagonal close packed cobalt through the formation of a Co2C intermediate. (C) 2012 Elsevier B.V. All rights reserved.