Abstract
An unpromoted ultrafine iron nano-particle catalyst was used for Fischer–Tropsch synthesis (FTS) in a CSTR at 270 °C, 175 psig, H2/CO = 0.7, and a syngas space velocity of 3.0 sl/h/g Fe. Prior to FTS, the catalyst was activated in CO for 24 h 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 400 h of synthesis time and after that remained nearly constant up to 600 h. 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 400 h 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 480 h 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 600 h of FTS. Large particles with the largest dimension larger than 150 nm 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 3–5 nm 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 10 nm suggesting that the growths of particles are not due to carbon deposition.
Similar content being viewed by others
References
Wender I (1996) Fuel Proce Technol 48:189
Steynberg AP (2004) In: Steynberg AP, Dry ME (eds) Fischer–Tropsch technology, studies in surface science and catalysis, vol 152. Elsevier, USA, p 8
Sarkar A, Neathery JK, Davis BH (2007) Separation of Fischer–Tropsch wax products from ultrafine iron catalyst particles, US DOE Final Technical Report, Contract # DE-FC26-03NT41965
Li S, Ding W, Meitzner GD, Iglesia E (2002) J Phys Chem B 106:85
Huang C-S, Ganguly B, Huffman GP, Huggins FE, Davis BH (1993) Fuel Sci Technol Int 11(9):1289
Zhao R, Goodwin JG, Jothimurugesan K, Gangwal SK, Spivey JJ (2001) Ind Eng Chem Res 40:1320
Shroff MD, Kalakkad DS, Coulter KE, Köhler SD, Harrington MS, Jackson NB, Sault AG, Datye AK (1995) J Catal 156:185
Pham HN, Datye AK (2000) Catal Today 58:233
Srinivasan R, Xu L, Spicer RL, Tungate FL, Davis BH (1996) Fuel Sci Technol Int 14(10):1337
Davis BH (1999) Technology development for iron Fischer–Tropsch Catalysis, US DOE Final Technical Report, Contract # DE-AC22-94PC94055-13
Kuo JCW, Sanzo FPD, Garwood WE, Gupte KM, Lang CK, Leib TM, Malladi M, Molina T, Nace DM, Smith J, Tarallo N, Kirk JF (1983) Slurry Fischer–Tropsch/mobil two-stage process of converting syngas to high octane gasoline, US DOE Final Technical Report, Contract # AC22-80PC30022
Bukur DB, Ma WP, Vazquez VC, Nowicki L, Adeyiga AA (2004) Ind Eng Chem Res 43:1359
O’Brien RJ, Xu L, Bao S, Raje A, Davis BH (2000) Appl Catal A 196:173
Kölbel H, Ralek M (1980) Catal Rev-Sci Eng 21:225
Niemantsverdriet JW, van der Krann AM, van Dijk WL, van der Baan HS (1980) J Phys Chem 84:3363
Butt JB (1990) Catal Lett 7:61
Sarkar A, Dozier AK, Graham UM, Thomas G, O’Brien RJ, Davis BH (2007) Appl Catal A: Gen 326:55
Rao KRPM, Huggins FE, Huffman GP, Gormley RJ, O’Brien RJ, Davis BH (1996) Energy Fuels 10:546
Rao KRPM, Huggins FE, Huffman GP, O’Brien RJ, Gormley RJ, Davis BH (1995) ACS Division Fuel Chem 40(1):153 (Preprints of Papers)
Jin Y, Xu H, Datye AK (2006) Microsc Microanal 12:124
Cullity BD, Stock SR (2001) Elements of X-ray diffraction, 3rd edn. Prentice Hall, Upper Saddle River, NJ, USA, p 118, 182
Morozova OS, Maksimov YV, Shashkin DP, Shirjaev PA, Matveyev VV, Zhorin VA, Krylov OV (1991) Appl Catal 78:227
PDF # 19-0629, JCPDS—International Center for Diffraction Data (2003)
PDF # 36-1248, JCPDS—International Center for Diffraction Data (2003)
Colliex C, Manoubi T, Ortiz C (1991) Phys Rev B 44(20):402
Allen T (1997) Particle size measurement, vol 1. Chapman and Hall, London, p 44
Dry ME (1981) In: Anderson JR, Boudart M (eds) Catalysis-science and technology. Springer-Verlag, New York, p 59
Emmett PH (ed) (1956) Crystallite phase and their relationship to Fischer–Tropsch catalysis. Reinhold, New York, p 407
Zarochak MF, McDonald MA (1986) Slurry-phase Fischer–Tropsch synthesis, CONF-86/288-1, Proceedings of Indirect Liquefaction Contractor’s Conference, December 2–4, 1986 at Monroeville, PA, USA
Raupp GB, Delgass WN (1979) J Catal 58:361
Li S, O’Brien RJ, Meitzner GD, Hamdeh H, Davis BH, Iglesia E (2001) Appl Catal A 219:215
Li S, Meitzner GD, Iglesia E (2001) J Phys Chem B 105:5743
Xu J, Bartholomew CH (2005) J Phys Chem B 109:2392
Loaiza-Gil A, Fontal B, Rueda F, Mendialdua J, Casanova R (1999) Appl Catal A: Gen 177:193
Eliason SA, Bartholomew CH (1997) Stud Surf Sci Catal 111:517
Dwyer DJ, Hardenbergh JH (1984) J Catal 87:66
Jin Y, Datye AK (2000) J Catal 196:8
Fernández A, Prieto P, Quirós C, Sanz JM, Martin JM, Vacher B (1996) Appl Phys Lett 69:764
Kim WJ, Ruano OA, Wolfenstine J, Frommeyer G, Sherby OD (1997) J Mater Res 12:2317
Acknowledgement
We acknowledge financial support for this work from U.S. Department of Energy (under contact DE-FC26-03NT41965) and the Commonwealth of Kentucky.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Sarkar, A., Seth, D., Dozier, A.K. et al. Fischer–Tropsch Synthesis: Morphology, Phase Transformation and Particle Size Growth of Nano-scale Particles. Catal Lett 117, 1–17 (2007). https://doi.org/10.1007/s10562-007-9194-6
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10562-007-9194-6