System Analysis of Methanol Synthesis by Carbon Dioxide Hydrogenation

Abstract

[Introduction] Carbon dioxide capture, utilization and storage is an important measure to achieve the goal of net zero greenhouse gas emission. The synthesis of methanol by carbon dioxide hydrogenation is one of the effective ways to use carbon, which can not only convert CO2 into methanol, an valuable fuel and chemical product, but also combine with producing hydrogen by electrolytic water, making methanol become the storage carrier of hydrogen. [Method] The methanol producing process by carbon dioxide hydrogenation was modelled by simulation software Aspen Plus. For the methanol production scale of 300,000 t/a, the hydrogen producing by water electrolysis was considered as the hydrogen source, and the influence of temperature, pressure and CO2/H2 feed ratio on methanol yield was analyzed in detail. [Result] The simulation results show the methanol yield is the highest when the synthesis temperature is around 250 °C and the CO2/H2 feed ratio is 7.33. Considering the direct combination with water electrolysis process, the synthesis pressure at around 5 MPa is reasonable. The water content of hydrogen has a certain effect on the methanol yield. The methanol yield only reduces 0.1 percent with the water content increase 100 kg/h in the raw H2. [Conclusion] The simulation determined the selection basis of key process parameters of methanol synthesis system by carbon dioxide hydrogenation. In addition, the feasibility of directly combining H2 obtained from water electrolysis with methanol synthesis process without drying and compression treatment is proved. In conclusion, hydrogen production from renewable sources combined with methanol synthesis by carbon dioxide hydrogenation is a technology with application prospect.