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 C-5(+) hydrocarbon selectivity of 72 wt% at 250 degreesC, 2.0 MPa, 2.0 NL/g-cat/h, and H-2/CO = 2.0. The test (550 h) in STSR indicated that the catalyst exhibited relatively high activity with CO conversion of 70-76% and C-5(+) selectivity of 83-86 wt% in hydrocarbon products under the conditions of 260 degreesC, 2.0 MPa, 2.0 NL/g-cat/h, and H-2/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. (C) 2004 Elsevier Ltd. All rights reserved.