Comparative Simulations of Cobalt- and Iron-Based Fischer-Tropsch Synthesis Slurry Bubble Column Reactors

Abstract

The influence of the catalyst type (Fe and Co) on CO and H2 conversions, CO2 selectivity, and the composition in Fischer-Tropsch synthesis slurry bubble column reactors was simulated for representative commercial-scale units (7 m i.d. and 30 m height). A nonisothermal, core-annulus multicompartment multicomponent two-bubble class model was used to account for a relatively detailed hydrodynamics. It was coupled to comprehensive Fischer-Tropsch synthesis and water−gas-shift reactions, in addition to descriptions of thermodynamics and thermal effects, variable gas flow rate due to chemical/physical contraction, and gas and slurry backmixing and (re)circulation. Two mechanistic kinetic models with consideration of olefin readsorption were employed to describe the paraffin and olefin formation with cobalt- and iron-based catalysts, in addition to relatively large activities for CO2 and oxygenate formation, mainly alcohols, for the latter catalyst. The influence of the temperature and superficial gas velocity o...