An active iron catalyst containing sulfur for Fischer–Tropsch synthesis

A precipitated iron catalyst containing sulfur for Fischer–Tropsch (F–T) synthesis was prepared by means of a novel method using a ferrous sulfate as precursor. Both fixed bed reactor (FBR) and continues stirred tank slurry reactor (STSR) were used to test long-term F–T reaction behaviors over the catalyst. A stability test (1600 h) in FBR showed that the catalyst was active even after 1500 h of time-on-stream with CO conversion of 78% and with C5+ hydrocarbon selectivity of 72 wt% at 250 °C, 2.0 MPa, 2.0 NL/g-cat/h, and H2/CO=2.0. The test (550 h) in STSR indicated that the catalyst exhibited relatively high activity with CO conversion of 70–76% and C5+ selectivity of 83–86 wt% in hydrocarbon products under the conditions of 260 °C, 2.0 MPa, 2.0 NL/g-cat/h, and H2/CO=0.67. The deactivation rate of the catalyst was low, accompanied by surprisingly low methane selectivity of 2.0–2.9 wt%. It is shown that a small amount of sulfur (existing as SO42−) may promote the catalyst by increasing activity and improving the heavier hydrocarbon selectivity. It is also comparable with other typical iron catalysts for F–T synthesis.