429514 Pretreatment Studies with a Precipitated Iron Catalyst for Fischer-Tropsch Synthesis Under Different Reaction Conditions

Wednesday, November 11, 2015
Exhibit Hall 1 (Salt Palace Convention Center)
Joshua Gorimbo1,2, David Glasser3, Diane Hildebrandt3 and Yali Yao2, (1)Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, South Africa, (2)Material and Process Synthesis, University of South Africa, Johannesburg, South Africa, (3)MaPS Engineering, University of South Africa, Johannesburg, South Africa

Fischer-Tropsch Synthesis (FTS) is a catalyzed chemical reaction in which synthesis gas (H2 +CO) is converted to clean fuels and chemicals. Catalyst pretreatment is an important stage in FT synthesis, which consists of reducing the catalyst using appropriate reducing agent, such as H2, CO or syngas.  Several papers have reported the effects of reducing agents on the catalytic performance under a fixed reaction condition.  However, only limited work has been done on the comparison of the catalyst activity and selectivity under different FT reaction conditions for the catalyst activated by H2, CO and syngas. With the aim of investigating the effect of the reducing agents on the catalyst performance under different reaction conditions, three fixed bed reactors, each loaded with 1 gram of the same iron based catalyst, were set in parallel and simultaneously reduced with H2, CO and syngas (CO/H2) for 48 hrs at 250 °C, at atmospheric pressure and a flowrate of 60 (NTP)ml/min. After the reduction, the FT reactions were performed at 250 oC, pressures of 1, 10 and 20 bar (gauge) and flowrates of 15, 30 and 60 (NTP)ml/min for a total time on stream (TOS) of 1000-hrs.The experimental data demonstrated that the CO consumption rate increased with increasing the feed flowrate and the following trend was obtained: CO < Syngas < H2 reduced catalyst. The results showed that the CO reduced catalyst produced more olefins followed by H2 and lastly syngas reduced, which indicated that the CO could be used as a reducing agent in the process aimed at producing mainly olefinic products. More experimental results, such as the effect of pressure on the reactant consumption rate and product formation rate as well as paraffin to olefin ratios were also measured and compared.

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