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.

In this work, an optimized process for methanol production using syngas from bi-reforming is proposed. The feed ratio (CH 4 /CO 2 /H 2 O) in the bi-reforming step, the purge stream quantity, and the heat recovery were optimized with the overall objective to reduce direct and indirect CO 2 emission in the process. The effect of the feed ratio on the rates of simultaneous reactions involved in bi-reforming (i.e., DR, SMR, and WGS) was investigated to understand the balance between the consumption and production of CO 2 relative to CH 4 . Compared to the conventionally used feed ratio of 3:1:2, this study found that the 1:1:2 ratio resulted in 100% CH 4 conversion and higher CO 2 consumption per mole of CH 4 in the bi-reforming step. A plantwide heat integration approach was adopted using pinch analysis to design a network of 27 heat exchangers. The implementation of a heat exchanger network resulted in the recovery of 221 MW of heat from process streams within the plant. With complementary optimization strategies, the proposed process resulted in ∼0.31 tonnes of CO 2 per tonne of methanol production, one of the lowest among the processes published in the literature.