Catalysis Today 154 (2010) 162–182 Contents lists available at ScienceDirect Catalysis Today journal homepage: www.elsevier.com/locate/cattod Deactivation of cobalt based Fischer–Tropsch catalysts: A review Nikolaos E. Tsakoumis a , Magnus Rønning a , Øyvind Borg b , Erling Rytter a,b , Anders Holmen a,∗ a Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway b Statoil R&D, Research Centre, Postuttak, NO-7005 Trondheim, Norway article info Article history: Available online 28 April 2010 Keywords: Fischer–Tropsch synthesis Cobalt Catalyst deactivation Review abstract To trace the origin of catalyst deactivation is in many cases difficult. It is usually a complex problem where several mechanisms contribute to the loss of activity/selectivity. Low temperature Fischer–Tropsch synthesis (FTS) is a three phase system having a wide range of products and intermediates. Addition- ally, high partial pressures of steam will arise during reaction. Thus, the chemical environment in the Fischer–Tropsch synthesis reactor encompasses a large number of interacting species which may nega- tively affect catalytic activity. Furthermore, it is an exothermic reaction and local overheating might occur. Utilization of the produced heat is crucial and the choice of the reactor should be done with respect to the catalyst stability properties. Catalyst deactivation in the Fischer–Tropsch reaction has been a topic of industrial as well as academic interest for many years. The main causes of catalyst deactivation in cobalt based FTS as they appear in the literature are poisoning, re-oxidation of cobalt active sites, for- mation of surface carbon species, carbidization, surface reconstruction, sintering of cobalt crystallites, metal–support solid state reactions and attrition. The present study focuses on cobalt catalyzed Fischer–Tropsch synthesis. The various deactivation routes are reviewed, categorized and presented with respect to the most recent literature. © 2010 Elsevier B.V. All rights reserved. Abbreviations: AES, Auger electron spectroscopy; AFM, atomic force microscopy; ASAXS, anomalous small angle X-ray scattering; BET, Brunauer–Emmett–Teller; CSTR, continuous stirred tank reactor; DFT, density functional theory; DOR, degree of reduction; DOS, density of states; DRIFTS, diffuse reflectance infrared Fourier transform spectroscopy; EDS, energy dispersive spectroscopy; EELS, elec- tron energy loss spectroscopy; EF-TEM, energy filtered-transmission electron microscopy; EXAFS, extended X-ray absorption fine structure; fcc, face cen- tered cubic; FT(S), Fischer–Tropsch (synthesis); GHSV, gas hourly space velocity; hcp, hexagonal close packed; HFS-LCAO, Hartree–Fock–Slater linear combination of atomic orbitals; HR-TEM, high resolution-transmission electron microscopy; HS-LEIS, high sensitivity-low energy ion scattering; HAADF, high angle annular dark field; ICP, inductively coupled plasma; IR, infrared; MES, Mössbauer emis- sion spectroscopy; MS, mass spectrometer; NEXAFS, near-edge X-ray absorption fine structure; PM-RAIRS, polarization modulation-reflection absorption infrared spectroscopy; ppb, parts per billion; ppm, parts per million; RBS, Rutherford backscattering spectrometry; ROR, reduction–oxidation–reduction; rpm, revolu- tions per minute; SBCR, slurry bubble column reactor; SIMS, secondary ion mass spectrometry; SSITKA, steady state isotopic transient kinetic analysis; STM, scanning tunneling microscopy; STP, standard temperature and pressure; TEM, transmission electron microscopy; TGA, thermogravimetric analysis; TOS, time on stream; TPD, temperature programmed desorption; TPO, temperature programmed oxidation; TPH, temperature programmed hydrogenation; TPR, temperature programmed reduction; UBI-QEP, unity bond index-quadratic exponential potential; UHV, ultra high vacuum; WGS, water–gas shift; XANES, X-ray absorption near edge structure; XAS, X-ray absorption spectroscopy; XPS, X-ray photoelectron spectroscopy; XRD, X-ray diffraction. ∗ Corresponding author. Tel.: +47 91897164. E-mail address: holmen@chemeng.ntnu.no (A. Holmen). 1. Introduction Modern Fischer–Tropsch technology aims at converting synthe- sis gas into long-chain hydrocarbons (FT waxes) [1]. A key element in improved Fischer–Tropsch technology is the development of active and stable catalysts with high wax selectivity. Cobalt is con- sidered the most favourable metal for the synthesis of long chain hydrocarbons due to its high activity, high selectivity to linear paraffins and low water–gas shift (WGS) activity. The catalyst usu- ally consists of Co metal particles dispersed on an oxide support. The Fischer–Tropsch synthesis (FTS) can be described by a chain growth mechanism where a C 1 unit is added to a growing chain. -olefins and paraffins are the primary products of the synthe- sis. -olefins can also participate in secondary reactions adding complexity to the reaction network. For cobalt catalysts oxygen is rejected as water which has a large effect on the activity and selec- tivity [2]. A number of oxygenates will be produced as well. N 2 , CH 4 and CO 2 that may be present in the feed are usually regarded as inert [3]. Catalyst deactivation is a major challenge in cobalt based Fischer–Tropsch synthesis. Combined with the relatively high price of cobalt, improved stability of the catalyst will add competitive- ness to the technology. Activity measurements in a demonstration plant have shown that two apparent regimes of deactivation exist [4]. The first initial deactivation regime (period A in Fig. 1) has been linked with reversible deactivation and lasts for a few days to weeks. The second long-term deactivation regime (period B in 0920-5861/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.cattod.2010.02.077