Thermodynamic assessment of tri-reforming of methane with optimization of operating conditions to achieve suitable syngas for methanol production

The present study consists of two parts. In the first part, a thermodynamic assessment of the reactions involved in the tri-reforming of methane (TRM) to syngas was conducted using a stoichiometric approach by simultaneously solving a system of nonlinear equilibrium equations. Using the results, the effects of operational variables, including temperature, pressure, and the molar ratios of H 2 O, CO 2 , and O 2 to CH 4 , were investigated on reactant conversions, product yields, and the H 2 /CO ratio. The results revealed that while increasing temperature promotes CH 4 and CO 2 conversions, H 2 O conversion exhibits a non-monotonic trend due to the competition between reforming and the reverse water-gas shift (RWGS) reaction. Higher temperatures and lower pressures generally enhance the yields of H 2 and CO, though the H 2 /CO ratio decreases as temperature rises. Furthermore, increasing the CO 2 feed ratios reduces the H 2 /CO ratio, whereas increasing the H 2 O ratio effectively enriches the syngas with hydrogen. In the second part, a Genetic Algorithm (GA) was employed to identify optimal operating conditions for producing syngas with a target H₂/CO ratio of 2.0, suitable for methanol synthesis, subject to CH 4 and CO 2 conversion constraints exceeding 90%. The optimal conditions were identified as: Temperature = 989 °C, Pressure = 1.0 bar, and a feed ratio of CH₄:H₂O: CO₂:O₂ = 1:0.61:0.30:0.10. Under these optimized parameters, a CH 4 conversion of 99.8% and a CO 2 conversion of 90.0% were achieved, yielding a syngas ratio of 1.99. These results are fully consistent with industrial requirements for methanol synthesis and align with the parametric sensitivity trends established in the thermodynamic analysis.