Simulation and analysis of green methanol synthesis in a plug-flow reactor

Abstract

This thesis examines green methanol synthesis from carbon dioxide and hydrogen in a plug-flow reactor using a MATLAB model. The work is motivated by growing interest in carbon capture and utilization and in power-to-methanol systems that combine captured CO₂ with renewable hydrogen. The model describes methanol synthesis through a set of reversible reactions involving CO hydrogenation, direct CO₂ hydrogenation, and the reverse water-gas shift reaction.

At baseline conditions of 498 K, 55 bar, and an 8 m reactor length, the model predicted a single-pass CO₂ conversion of about 20.6%. Methanol and water are the main products, while carbon monoxide is also formed through the competing reverse water-gas shift reaction. The temperature analysis showed that reactor performance improved up to an intermediate temperature, with the highest outlet CO₂ conversion of about 27% obtained at 520 K, while further heating reduced the benefit because of less favorable equilibrium conditions. Increasing reactor length also improved conversion, although the gain became smaller toward the reactor outlet. A brief recycle sensitivity test also examines the system qualitatively, indicating that recycle could increase overall CO₂ conversion but also strongly increase internal gas circulation. Overall, the model captures the main trends of CO₂ to methanol synthesis and provides a useful basis for analysis of reactor behavior.