The synthesis of Fischer Tropsch is an important technology in gas-to-liquids conversion processes, which allows the conversion of synthesis gas into a mixture of hydrocarbons. The thermodynamic modeling of this system can be performed by chemical and phase equilibrium calculations, where the minimization of the Gibbs energy is the necessary condition for solving the problem. The addition of adsorption parameters were employed in the methodology to evaluate the influence of catalyst in the products. The presence of the catalyst and its quantity affects the mass balance of the system because more species may or may not adsorb on the surface of the solid.