Fixed bed and slurry reactor studies of Fischer-Tropsch synthesis on precipitated iron catalyst

Abstract

A sample of commercial Ruhrchemie catalyst (100 Fe/4.3 Cu/4.1 K/25 SiO 2) for the Fischer-Tropsch synthesis was tested in a fixed bed and in a slurry reactor at process conditions similar to those used in commercial reactors. The apparent reaction rate constant, calculated assuming that the reaction rate has a first order dependence on hydrogen pressure, was nearly the same in both reactors during the first 380 h on stream. The catalyst deactivated slowly with time-on-stream in both reactors, while the hydrocarbon selectivity shifted towards lower molecular weight products. Secondary reactions (l-alkene hydrogenation and isomerization) increased gradually with time-on-stream in the slurry reactor, whereas the opposite trend was observed in the fixed bed reactor. The effects of process conditions on the catalyst activity and product selectivities (hydrocarbon product distribution, total alkene content, 2-alkene selectivity, organic oxygenates) were also investigated.