Optimum Feed Ratio Analysis for Tri-Reforming of Methane Using Thermodynamic Equilibrium Method

Abstract

Tri-reforming of methane was studied in this work through a method called Gibbs free energy minimization or thermodynamic equilibrium. Optimum feed ratios of H₂O/CH₄ and CO₂/CH₄ at a specific O₂/CH₄ ratio were investigated based on optimum conditions which are CH₄ and CO₂ conversions are equal to or higher than 90%, H₂/CO ratio is 2.0 and H₂ yield should be as high as possible. Carbon formation during reaction was also focused for each case of the optimum feed ratio. Moreover, heat required to raise the reaction temperature was calculated and presented in terms of CO₂ equivalent. Net CO₂ emission from the process was finally expressed. The results showed that the values of optimum H₂O/CH₄ and CO₂/CH₄ ratios reduce as O₂/CH₄ ratio increases. The values of carbon selectivity, reflecting solid carbon formation, are very low. The net CO₂ emission is in the range of 0.176-0.137 kmol per 1 kmol of CH₄

Keywords: Tri-reforming; CO₂ emission; Hydrogen production; Thermodynamic equilibrium