caa a22 4500 463253892 CHVBK 20180405153348.0 cr unu---uuuuu 170326e20070801xx s 000 0 eng 10.1007/s10562-007-9194-6 doi (NATIONALLICENCE)springer-10.1007/s10562-007-9194-6 Fischer-Tropsch Synthesis: Morphology, Phase Transformation and Particle Size Growth of Nano-scale Particles [Elektronische Daten] [Amitava Sarkar, Deepyaman Seth, Alan Dozier, James Neathery, Hussein Hamdeh, Burtron Davis] An unpromoted ultrafine iron nano-particle catalyst was used for Fischer-Tropsch synthesis (FTS) in a CSTR at 270°C, 175psig, H2/CO=0.7, and a syngas space velocity of 3.0sl/h/g Fe. Prior to FTS, the catalyst was activated in CO for 24h which converted the initial hematite into a mixture of 85% χ-Fe5C2 and 15% magnetite, as found by Mössbauer measurement. The activated catalyst results in an initial high conversion (ca. 85%) of CO and H2; however the conversions decreased to ca. 10% over about 400h of synthesis time and after that remained nearly constant up to 600h. Mössbauer and EELS measurement revealed that the catalyst deactivation was accompanied by gradual in situ re-oxidation of the catalyst from initial nearly pure χ-Fe5C2 phase to pure magnetite after 400h of synthesis time. Experimental data indicates that the nucleation for carbide/oxide transformation may initiates at the center of the particle by water produced during FTS. Small amount of ɛ′-Fe2.2C phase was detected in some catalyst samples collected after 480h of FTS which are believed to be generated by syngas during FTS. Particle size distribution (PSD) measurements indicate nano-scale growth of individual catalyst particle. Statistical average diameters were found to increase by a factor of 4 over 600h of FTS. Large particles with the largest dimension larger than 150nm were also observed. Chemical compositions of the larger particles were always found to be pure single crystal magnetite as revealed by EELS analysis. Small number of ultrafine carbide particles was identified in the catalyst samples collected during later period of FTS. The results suggest that carbide/oxide transformation and nano-scale growth of particles continues either in succession or at least simultaneously; but definitely not in the reverse order (in that case some larger carbide particles would have observed). EELS-STEM measurement reveals amorphous carbon rim of thickness 3-5nm around some particles after activation and during FTS. Well ordered graphitic carbon layers on larger single crystal magnetite particles were found by EELS-STEM measurement. However the maximum thickness of the carbon (amorphous or graphitic) rim does not grow above 10nm suggesting that the growths of particles are not due to carbon deposition. Springer Science+Business Media, LLC, 2007 Fischer-Tropsch synthesis nationallicence Iron catalyst nationallicence Phase transformation nationallicence Iron carbide nationallicence Amorphous carbon nationallicence Graphitic carbon nationallicence Nano-scale growth nationallicence Particle size distribution nationallicence Sarkar Amitava Center for Applied Energy Research, University of Kentucky, 2540 Research Park Drive, 40511-8479, Lexington, KY, USA aut Seth Deepyaman Department of Chemical Engineering, University of Waterloo, N2L 3G1, Waterloo, ON, Canada aut Dozier Alan Chemical and Materials Engineering Department, University of Kentucky Electron Microscopy Center, A004 ASTeCC Building 0286, 40506, Lexington, KY, USA aut Neathery James Center for Applied Energy Research, University of Kentucky, 2540 Research Park Drive, 40511-8479, Lexington, KY, USA aut Hamdeh Hussein Physics Department, Wichita State University, 67260, Wichita, KS, USA aut Davis Burtron Center for Applied Energy Research, University of Kentucky, 2540 Research Park Drive, 40511-8479, Lexington, KY, USA aut Catalysis Letters Springer US; http://www.springer-ny.com 117/1-2(2007-08-01), 1-17 1011-372X 117:1-2<1 2007 117 10562 https://doi.org/10.1007/s10562-007-9194-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10562-007-9194-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sarkar Amitava Center for Applied Energy Research, University of Kentucky, 2540 Research Park Drive, 40511-8479, Lexington, KY, USA aut NATIONALLICENCE 700 1- Seth Deepyaman Department of Chemical Engineering, University of Waterloo, N2L 3G1, Waterloo, ON, Canada aut NATIONALLICENCE 700 1- Dozier Alan Chemical and Materials Engineering Department, University of Kentucky Electron Microscopy Center, A004 ASTeCC Building 0286, 40506, Lexington, KY, USA aut NATIONALLICENCE 700 1- Neathery James Center for Applied Energy Research, University of Kentucky, 2540 Research Park Drive, 40511-8479, Lexington, KY, USA aut NATIONALLICENCE 700 1- Hamdeh Hussein Physics Department, Wichita State University, 67260, Wichita, KS, USA aut NATIONALLICENCE 700 1- Davis Burtron Center for Applied Energy Research, University of Kentucky, 2540 Research Park Drive, 40511-8479, Lexington, KY, USA aut NATIONALLICENCE 773 0- Catalysis Letters Springer US; http://www.springer-ny.com 117/1-2(2007-08-01), 1-17 1011-372X 117:1-2<1 2007 117 10562 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer