THERMODYNAMIC ANALYSIS OF FISCHER-TROPSCH SYNTHESIS EMPLOYING GIBBS ENERGY MINIMIZATION APPROACH

摘要

The Fischer-Tropsch Synthesis (FTS) is an important technologyrnfor gas-to-liquids conversion process, which allowsrnthe conversion of syngas, (CO and H_2) produced from naturalrngas, coal, waste or biomass, in a mixture of hydrocarbonsrnsuch as light olefins, alcohols and other products. Thernthermodynamic modelling of such system can be made byrnchemical and phase equilibrium employing the minimizationrnof the Gibbs free energy. Thermodynamic equilibriumrncalculation can be computed as an optimization problem,rngiven certain constraints. The present work investigated thernphase and chemical equilibrium of Fischer-Tropsch processrnthrough the minimization of the Gibbs energy of the system,rnwith the objective to determine the most thermodynamicrnfavorable phases and compositions of the formed FTS products.rnThe software GAMS is used to solve the proposedrnproblem. The restrictions of non-negativity of the numberrnof moles and the non-stoichiometric balance are used; thirtyrnthree possible chemical species (linear paraffins, linear alpharnalkenes and alcohols besides carbon monoxide, carbonrndioxide, water and hydrogen) were considered. The effectsrnof temperature (300-900 K), pressure (1-30 bar) and H_2:COrnratio (2:1 and 3:1) are evaluated.