Available online at www.sciencedirect.com Recent advances in understanding the Fischer–Tropsch synthesis (FTS) reaction David Glasser, Diane Hildebrandt, Xinying Liu, Xiaojun Lu and Cornelius M Masuku Because of the world energy crisis, there has been renewed interest in the Synthesis (Fischer–Tropsch synthesis (FTS)) reaction over the last few years. In spite of the fact that it has been studied for over 80 years an adequate description of its kinetics still seems to escape us. There are still significant experimental results that do not appear to fit in with any current theories. In this review we will look at some new results covering a wide range of areas but will focus on some that may help to throw light on the phenomena occurring during reaction. This will include the overall reaction and some selectivity issues particularly the olefin to paraffin ratios of the lower hydrocarbons. Address Centre of Material and Process Synthesis, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Private Bag 3, WITS 2050, Johannesburg, South Africa Corresponding author: Glasser, David (David.Glasser@wits.ac.za) Current Opinion in Chemical Engineering 2012, 1:296–302 This review comes from a themed issue on Reaction engineering and catalysis Edited by Theodore T Tsotsis For a complete overview see the Issue and the Editorial Available online 26th February 2012 2211-3398/$ – see front matter, # 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.coche.2012.02.001 Review of recent developments in the FTS Reaction mechanism The Fischer–Tropsch (FT) reaction mechanism is still an issue of contention [1,2]. Recently, a combination of density functional theory (DFT) calculations and kinetic analyses has been used to study the FT reaction mech- anism [3–5]. Many apparently different mechanisms have been proposed, but common to them all is the concept that a stepwise chain growth process is involved. This is supported by the fact that the carbon number product distributions calculated on probabilities of chain growth match the experimentally observed results obtained in different reactor types and sizes over widely varying process conditions with different catalysts. Catalysts Fischer–Tropsch synthesis (FTS) catalyst research and development is a lively area, but because of space limitations we will not be able to focus on this in the review. However, of particular interest is the deactivation and regeneration of cobalt catalysts. Saib et al. [6  ] ident- ified sintering of Co active phase, carbon deposition and surface reconstruction as the intrinsic deactivation mech- anisms. They therefore suggested a three-step regener- ation process: de-waxing, oxidation and reduction to reverse the sintering, carbon deposition and surface re- construction that takes place during FTS. Kinetics Kinetic models of FTS on cobalt, iron and ruthenium catalysts have received considerable attention [7–12] from researchers in the past but not recently. The major problem in describing the FT reaction kinetics is the apparent complexity of the reaction mechanism and the large number of species involved. When one looks at the kinetic studies in the literature, one finds that there are a variety of rate expressions as well as a wide range of activation energies for both Co and Fe catalysts. This raises questions about which of these data, kinetic parameters and rate expressions can be relied on for estimating reaction rates and/or conducting preliminary reactor design [13]. This strongly suggests that the com- plex FT reaction behaviour may not be described effi- ciently by kinetics alone. This point is addressed at a later stage. Reactors The simulation of slurry reactors for FTS has received attention in the past. Much work is still being published pursuing better and more accurate models for industrial applications [14–18]. The recent development of micro- structured or/and micro-channel catalytic reactors for FTS [19–21,22  ] is also of much interest as those reactors potentially offer better heat transfer and lower pressure drop with smaller catalyst particles, therefore improving the efficiency of the catalyst and the reactor. It also avoids the difficulty of wax/catalyst separation. However regen- erating or replacing the catalyst may be a problem. In order to increase the efficiency of the reactor researchers have also developed a thermally-coupled reactor system for the FTS [23]. Heat transfer The importance of heat transfer in a fixed bed reactor still receives a lot of attention. One aspect is trying to develop catalysts or structured catalyst to improve the effective heat transfer coefficient of the catalyst bed [24,25]. Current Opinion in Chemical Engineering 2012, 1:296–302 www.sciencedirect.com