Simulations and Optimization of a Reduced CO₂ Emission Process for Methanol Production Using Syngas from Bi-reforming

A low CO₂ emission process for methanol production using syngas generated by combined H₂O and CO₂ reforming with CH₄ (bi-reforming) is proposed in this work. A detailed process model was developed using Aspen Plus. The operating conditions of the bi-reforming and methanol synthesis were derived from a detailed sensitivity analysis using plug flow reactor models with Langmuir–Hinshelwood–Hougen–Watson (LHHW) kinetics. A molar feed ratio of CH₄:CO₂:H₂O of 1:1:2, instead of conventional 3:1:2 in the bi-reforming was found to be optimum and resulted in ∼99% conversion of CH₄, 44% conversion of CO₂, and a H₂/CO ratio of 1.78 at 910 °C and 7 bar. A higher methane conversion eliminated the need for cryogenic separation of CH₄. The optimum feed ratio of 1:1:2 resulted in an ∼33% higher consumption of CO₂ per mole of CH₄ required than the conventional process. An acid gas removal process using MDEA was used for CO₂ separation, and a network of heat exchangers was configured for heat recovery. The proposed process resulted in ∼0.37 tonne of CO₂ per tonne of methanol, which is ∼2–4 times lower than several published data and commercial methanol processes.