A long term study of the gas phase of low pressure Fischer-Tropsch products when reducing an iron catalyst with three different reducing gases

• Published in: Applied catalysis. A, General Vol. 534; pp. 1 - 11
• Main Authors: Gorimbo, Joshua, Lu, Xiaojun, Liu, Xinying, Hildebrandt, Diane, Glasser, David
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.03.2017; Elsevier Science SA
• Subjects: Alkenes; Carbon monoxide; Catalysis; Catalysts; Conversion; Fischer-Tropsch process; Fischer-Tropsch synthesis; Flow velocity; Gases; Hydrogen; Iron; Iron catalyst; Low pressure; Methane; Olefins/paraffin ratio; Reactors; Reducing agents; Reducing gases; Selectivity; Synthesis gas; Fischer-Tropsch synthesis; Olefins/paraffin ratio; Low pressure; Iron catalyst; Selectivity; Reducing gases; Conversion
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2017.01.013

[Display omitted] •Low pressure Fischer Tropsch was run at 1bar(g) for more than 1000h time on stream (TOS).•Iron catalyst reduced with different reducing gases gave same activity but different product selectivities.•Iron catalyst deactivation at 1bar (g) pressure insiginificant after 1000 TOS.•Reducing with CO produces more olefinic hydrocarbons. Low pressure Fischer-Tropsch synthesis was tested using iron catalysts reduced by three different reducing gases. In this regards, three reactors were set up in parallel and each of them loaded with the same quantity of the iron catalyst (FeCuKSiO2). After loading, the catalysis in the first reactor was reduced with synthesis gas (a combination of carbon monoxide and hydrogen). The catalyst in the second reactor was reduced using hydrogen (H2) gas, and while that in the third reactor was reduced with carbon monoxide (CO) gas. In this study only the gas-phase products leaving the reactors were analysed and compared under the same operating conditions such as flow rate, pressure and temperature for 1000h TOS. The results obtained indicate that the initial use of different reducing agents does not have a large impact on the long term catalyst activity but does have an impact on long term selectivity. The three reactors stabilize to about the same overall CO conversion of 14.5% which corresponds to a consumption rate of 2.64×10−4mol/min.gcat (reactivity) after about 150h while the selectivities in the three reactors are not the same. Methane selectivity showed the trend: Carbon monoxide reduced>Syngas reduced>Hydrogen reduced. Furthermore, reducing with CO gives much more olefins than reducing with syngas and H2. The paraffin production rates did not follow a consistent trend.