Abstract
The use of biomass to produce environmental cleaner fuels has been gaining more attention in the past decades due to the socio-economic benefits over the petrochemical route. For instance, the conversion of synthesis gas (H2 and CO) obtained from biomass into fuel using Fischer-Tropsch (FT) process and catalysts, which is conventionally based on iron and cobalt. This process generates a mixture of light olefins, wax, gasoline, diesel, and alcohols. In fact, operating conditions (such as temperature, pressure, H2/CO ratio and catalyst composition) can predict the FT products range. The thermodynamic modeling of this system is calculated by phase and chemical equilibrium, applying global optimization techniques to minimize the Gibbs energy of the system, subject to the restrictions of stoichiometric balances for each reaction considered and non-negativity of the number of moles. In addition, the catalytic effect is taken into account in the constraints of the model. Thus, the purpose of this work is the evaluation of the chemical equilibrium for the multiphase mixture (alkenes, alkanes, alcohols, CO2, H2O, H2, and CO) in order to provide the phase composition for the FT process. The thermodynamic modeling was developed with a non-linear program (NLP) and solved by GAMS (General Algebraic Modeling System) software with the CONOPT3 solver. Moreover, we analyzed the effect of operating conditions (temperature, pressure, and H2/CO molar ratio), considering an ideal system (Raoult’s law) in the liquid phase for the thermodynamic characterization.
