Fischer–Tropsch Synthesis: Effect of Reaction Temperature for Aqueous-Phase Synthesis Over a Platinum Promoted Co/Alumina Catalyst Venkat Ramana Rao Pendyala • Wilson D. Shafer • Gary Jacobs • Burtron H. Davis Received: 9 January 2014 / Accepted: 24 March 2014 / Published online: 8 April 2014 Ó Springer Science+Business Media New York 2014 Abstract The effect of reaction temperature on the per- formance of a traditional Fischer–Tropsch cobalt catalyst (0.5 % Pt–25 % Co/Al 2 O 3 ) was investigated during aque- ous-phase Fischer–Tropsch synthesis (AFTS) using a 1 L stirred tank reactor in the batch mode of operation. The CO conversion rate of the catalyst was found to increase monotonically with increasing reaction temperature. At lower temperatures oxygenate selectivity was high. With increasing the reaction temperature, oxygenate selectivity decreased and the selectivity to hydrocarbons increased. Carbon dioxide and methane selectivity also increased with reaction temperature and the corresponding higher hydro- carbon (C 5 ?) selectivity decreased. For comparison, the CO conversion rate of the catalyst was also tested using C 30 oil as a solvent, and similar activation and reaction con- ditions were utilized in the batch mode of operation. Slightly higher CO rate was observed with C 30 oil as a solvent than with the water. Keywords Aqueous-phase Fischer–Tropsch synthesis  Traditional cobalt catalyst  Comparison between aqueous and non-aqueous solvents  Activity  Product selectivity 1 Introduction Fischer–Tropsch synthesis (FTS) is receiving renewed attention, driven by the global need to convert non-petro- leum based energy resources into fuels and chemicals. FTS is a process used to produce hydrocarbons from syngas (a mixture of H 2 and CO), which can be obtained from bio- mass, coal, and natural gas by gasification and/or reforming [1, 2]. This process is advantageous in several ways: liquid fuels produced in this manner are lower in sulfur com- pounds and in heavy metals compared to those derived from crude oil and may be regarded as having a reduced environmental impact. As a result, the use of FT synthesis is considered a viable approach to mitigating depleted fossil fuel resources and to reducing environmental pollu- tion [3, 4]. To date, various metal catalysts have been investigated for use in FT synthesis, and it is well known that Fe, Co, Ni and Ru are active in this respect [5–10]. Considerable technical development has taken place in the FTS process in terms of improved reactors and synthesis of efficient cobalt- or iron-based catalysts for industrial applications [11–13]. Because of the high conversion per pass that can be achieved, and the relatively low deacti- vation rate during FTS, cobalt catalysts are useful for synthesizing long-chain hydrocarbons [9]. Cobalt-cata- lyzed FTS typically proceeds at 200–230 °C, 20–40 bar, and a H 2 /CO ratio of 1.6–2 on metal cobalt sites dispersed on the surface of a refractory oxide support. Two of the most important factors in determining the active cobalt surface site density that are relevant to the FTS reaction are precursor reducibility and metal dispersion. Water is a major product of the FT synthesis over cobalt catalysts, and the influence of water on this reaction is still uncertain. In one work [14], the findings of numerous publications on water effects on Co-based catalysts sup- ported on different carrier materials have been summa- rized. Co supported on a carrier with larger pores (and lower surface areas) generally tends to be positively affected by moderate amounts of water, while the FT rate of catalysts with smaller pores is often reduced. Different explanations of the positive effect of water on the FT rate V. R. R. Pendyala  W. D. Shafer  G. Jacobs  B. H. Davis (&) Center for Applied Energy Research, University of Kentucky, 2540 Research Park Dr., Lexington, KY 40511, USA e-mail: burtron.davis@uky.edu 123 Catal Lett (2014) 144:1088–1095 DOI 10.1007/s10562-014-1247-z