A simple and realistic fixed bed model for investigating Fischer–Tropsch catalyst activity at lab-scale and extrapolating to industrial conditions

In the present work, a ready-to-use tool in the form of a comprehensive fixed-bed reactor model (2-dimensional, pseudo-homogeneous, gas–solid and steady state model) for Fischer–Tropsch synthesis is proposed. The model is based on the main governing processes in terms of physical and chemical laws and considers internal mass transfer resistance. The model allows: (a) determining kinetic parameters from laboratory experiments; (b) estimating productivity, CO conversion, selectivities (CH4 and C5+) under relevant industrial conditions for various catalyst structures (foam, extrudates, grains, etc.). The application of this tool in basic scale-up studies is illustrated in the simulation of a three-stage FT unit of 30,000 barrels/day of diesel+naphtha. It is shown that a foam catalyst allows better performances (activity per unit mass, C5+ selectivities and overall pressure drop) than packed extrudates, but at the expense of higher catalyst and reactor volumes.