Journal of Natural Gas Chemistry 19(2010)284–292 Fischer-Tropsch synthesis by nano-structured iron catalyst Ali Nakhaei Pour 1,2∗ , Mohammad Reza Housaindokht 1 , Sayyed Faramarz Tayyari 1 , Jamshid Zarkesh 2 1. Department of Chemistry, Ferdowsi University of Mashhad, P.O.Box91775-1436, Mashhad, Iran; 2. Research Institute of Petroleum Industry of National Iranian Oil Company, Gas Research Division, P.O.Box14665-137, Tehran, Iran [ Manuscript received August 24, 2009; revised September 30, 2009 ] Abstract Effects of nanoscale iron oxide particles on textural structure, reduction, carburization and catalytic behavior of precipitated iron catalyst in Fischer-Tropsch synthesis (FTS) are investigated. Nanostructured iron catalysts were prepared by microemulsion method in two series. Firstly, Fe 2 O 3 , CuO and La 2 O 3 nanoparticles were prepared separately and were mixed to attain Fe/Cu/La nanostructured catalyst (sep-nano catalyst); Secondly nanostructured catalyst was prepared by co-precipitation in a water-in-oil microemulsion method (mix-nano catalyst). Also, conventional iron catalyst was prepared with common co-precipitation method. Structural characterizations of the catalysts were performed by TEM, XRD, H 2 and CO-TPR tests. Particle size of iron oxides for sep-nano and mix-nano catalysts, which were determined by XRD pattern (Scherrer equation) and TEM images was about 20 and 21.6 nm, respectively. Catalyst evaluation was conducted in a fixed-bed stainless steel reactor and compared with conventional iron catalyst. The results revealed that FTS reaction increased while WGS reaction and olefin/paraffin ratio decreased in nanostructured iron catalysts. Key words Fischer-Tropsch synthesis; iron-based catalyst; nano-particle 1. Introduction Fischer-Tropsch synthesis (FTS) is an industrially impor- tant process for the conversion of syngas (H 2 /CO) derived from carbon sources such as coal, peat, biomass, and natu- ral gas into hydrocarbons and oxygenates [1-3]. FTS prod- uct consists of a complex multicomponent mixture of linear and branched hydrocarbons and oxygenated compounds. Fu- els produced by the FTS are of a high quality due to a very low aromatic and zero sulfur content. Considerable progresses have been made in the past two decades on the development of more active and selective cobalt and iron catalysts and more effective reactor/process technologies [4,5]. Iron based cata- lyst systems have remained a preferred choice in commercial FTS plants due to low cost and tendency to yield high amounts of olefines in hydrocarbon distribution. But it is well known that low product selectivity, catalyst agglomeration and sinter- ing limit use of the iron catalysts in high temperate operations [5-11]. Recent studies showed nanosized iron particles were essential to achieve high FTS activity [12-22]. The prepara- tion method plays an important role in physical properties and performance of catalysts [16-22]. In the last years, use of mi- croemulsion method has been developed in order to synthesize nanoparticles with controlled size and homogeneous distribu- tion of elements [16–20]. Microemulsion system is optically transparent and has thermodynamically stable dispersion of water phase into an organic phase, which is stabilized by a surfactant [21]. If the minority phase is the aqueous one, then reversed micelles are obtained. Considering advantages such as rendering nanosized particles, displaying high surface area and low microporosity, microemulsion is an ideal technique to prepare materials containing two (or more) metallic or oxide phases [16]. In a microemulsion system, different species (ox- ide precursors) are homogeneously mixed within the micelles. Therefore, rendering solids display high internal homogene- ity and optimal interactions between the constituents [16–20]. Some authors prepared supported iron-based Fischer-Tropsch catalysts by microemulsion method, and reported high activ- ity and selectivity to oxygenates. However, there are still few works dealing with the preparation of non-supported catalysts even though the synthesis of mixed oxides by microemulsion has been reported [20-22]. ∗ Corresponding author. Tel/Fax: +98 21 44739716; E-mail: nakhaeipoura@ripi.ir and nakhaeipoura@yahoo.com Copyright©2010, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. All rights reserved. doi:10.1016/S1003-9953(09)60059-1