Methanol synthesis from biogas: A thermodynamic analysis

A new approach for the direct conversion of syngas into methanol has been proposed as alternative tothe conventional process requiring WGS and/or PSA clean-up steps for syngas upgrading. A comparativethermodynamic equilibrium analysis of biogas reforming processes (dry reforming, steam reforming andoxy-steam reforming) has been performed using the Gibbs free energy minimization method. The calculationshave been carried out under different biogas composition (CH4/CO2 ¼ 1e2.3), reaction temperature(400e900 C), S/CH4 (0.0e3.0) and O2/CH4 (0.0e0.2) molar ratios. The effects of processvariables on the reforming performances as well as on the syngas quality, in term of CH4 and CO2conversion, H2/CO and H2/CO2 ratios, coke deposition and energetic consumption, has been examined.Subsequently, methanol synthesis has been studied using the same mathematical approach, with the aimto identify the most adequate operating conditions for the direct conversion of the syngas obtained fromreforming process into methanol. The simulations suggested that steam reforming of biogas, with highmethane content, is the most appropriate route to produce a syngas quality suitable for the new proposedapproach.