(493d) DFT and Microkinetic Modeling Study of Gas- and Liquid-Phase Fischer-Tropsch Synthesis

Fischer-Tropsch (FT) synthesis has been applied for the production of valuable fuel products from synthesized gas (syngas) for decades. Currently, conventional FT processes in industry are accomplished in both gaseous and liquid phases. In spite of several suggested mechanisms, the actual reaction path and important elementary reaction steps that result in different products under different conditions are still under investigation, especially in the liquid phase. This work involves a density functional theory (DFT) study of an existing microkinetic model for gas-phase FT synthesis on Co(0 0 1) catalyst. In this regard, by utilization of the DFT-GGA method, the kinetic and thermodynamic parameters of each elementary step have been evaluated. Then, using DFT calculations with the COSMO continuum solvent model, FT synthesis has been studied in the presence of n-hexane solvent to find the impact of liquid solvent (i.e. solvation effects) on the kinetics, mechanism, and thermodynamics of this process. In addition, liquid-phase reactor operating conditions (PVT behavior) are evaluated using an equation of state. Finally, by introducing these elementary mechanistic parameters in a simulated reactor, FT product yields and distributions in the different phases are calculated and compared.