281050 Fischer-Tropsch Synthesis Using H2/CO/CO2 Syngas Mixtures: A Comparison of Product Distribution for Iron and Cobalt Based Catalysts

Monday, October 29, 2012: 8:50 AM
315 (Convention Center )
Yali Yao, Xinying Liu, Diane. Hildebrandt and David Glasser, Centre of Material and Process Synthesis, University of the Witwatersrand, Johannesburg, South Africa

Fischer-Tropsch synthesis (FTS) using H2/CO/CO2 syngas mixtures over cobalt- and iron-based catalysts were carried out in a fixed-bed micro reactor. The data show that: (1) For CO2-rich feeds, most of the products are short chain paraffins with high methane selectivity, and the product distribution follows a typical one-alpha Anderson-Schulz-Flory (ASF) distribution with low alpha values; (2) For CO-rich feeds, the product composition shifts to an FT type product (mainly long chain hydrocarbons), and follows a two-alpha ASF distribution with high alpha values.

The growth factors for paraffin, olefin and oxygenate produced by means of FTS differ. We therefore introduce a new product distribution model entailing a combination of the paraffin and olefin product growth factors to explain the observed two-alpha ASF distribution of FTS. This model shows the likelihood that two-alpha product distribution may be the result of the combination of different product spectrums. We also considered the effect of the vapour-liquid equilibrium (VLE) on the product distribution, and found that our experimental data support the postulate that the double-alpha type plot often encountered in FT results is attributable to VLE.

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See more of this Session: CO Hydrogenation I
See more of this Group/Topical: Catalysis and Reaction Engineering Division