Kinetics modeling of Fischer–Tropsch synthesis on the unsupported Fe-Co-Ni (ternary) catalyst prepared using co-precipitation procedure Ali Akbar Mirzaei ⇑ , Razieh Sarani, Hamid Reza Azizi, Samaneh Vahid, Hasan Oliaei Torshizi Department of Chemistry, Faculty of Sciences, University of Sistan and Baluchestan, Zahedan 98135-674, Iran highlights  Associative adsorbed CO and associative adsorbed H 2 were main steps in mechanism.  The activation energy was found to be 79.88 kJ/mol for the best model.  The logarithm of the rate constant as a function of reverse of temperature showed a plot with the negative slope of E a /R.  Preparing methods and compounds with a constant active phase are two main factors that dominate kinetic and mechanisms. graphical abstract article info Article history: Received 19 May 2014 Received in revised form 15 July 2014 Accepted 11 September 2014 Available online 7 October 2014 Keywords: Fischer–Tropsch synthesis co-precipitation Iron–Cobalt–Nickel catalyst Fixed-bed reactor Kinetic modeling abstract An active Iron-Cobalt-Nickel catalyst was prepared using co-precipitated method and tested for CO hydrogenation to light olefins in Fischer–Tropsch synthesis. The kinetic experiments were performed in a fixed-bed reactor as follows: T = 250–270 °C, P = 1–7 bar, GHSV = 6000 h 1 and H 2 /CO feed ratio (mol/mol) = 1–2.5. On the basis of various mechanisms and LHHW type rate equations, eighteen kinetic expressions for CO consumption were tested and the best fitted model is achieved. The kinetic parame- ters were estimated with non-linear regression method. The obtained energy of activation was 79.88 kJ/ mol for optimal kinetic model. The catalyst characterization was carried out using different methods including XRD, SEM and BET. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Catalysis is at the heart of most modern industrial processes [1,2]. Although the metals Ni, Fe, Co, Ru and Rh have the required FTS activity for commercial uses; under the practical operation, but only Co- and Fe-based catalysts have been developed for industrial uses [3,4]. Iron-based catalyst systems have low cost and have ten- dency to yield high amounts of olefins in hydrocarbon distribution [5–10]. Many studies have been reported that a mixture of the two or most active catalysts, Fe and Co (Fe–Co bimetallic catalysts) has generated product streams in the FT reaction richer in high olefins than expected from either Fe or Co catalysts [11–16]. Ni shows dif- ferent catalytic behavior, since the molecular weight of the result- ing hydrocarbons is much lower for Ni than Fe and Co catalysts [17]. Therefore addition of Ni to Fe or Co catalysts leads to signifi- cant increase in light olefins formation. Kinetics molding and kinetics description are two main factors that are very important http://dx.doi.org/10.1016/j.fuel.2014.09.093 0016-2361/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +98 (541) 8056331; fax: +98 (541) 2446888. E-mail address: mirzaei@hamoon.usb.ac.ir (A.A. Mirzaei). Fuel 140 (2015) 701–710 Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel