Multi-objective Optimization of a Methanol Synthesis Process Superstructure with Two-step Carbon Dioxide Consumption

Abstract Methanol synthesis is a well-known and important process capable of consuming carbon dioxide. The increasing use of CO 2 , however, affects negatively on the cost. In this paper, we study the production of methanol from syngas using different sources. We perform a multi-objective optimization of the process to determine the trade-offs between CO 2 utilization and cost. The Pareto set of solutions shows that partial oxidation of methane (POX) achieves the minimum cost along with CO 2 concentrations of 5 % of the total carbon contained in the syngas and a M  = ( H 2  −  CO 2 )/( CO  +  CO 2 ) ratio of 2.00. The synergistic combination of steam methane reforming (SMR) and dry methane reforming (DMR) stands out as the most environmentally friendly solution, and requires CO 2 percentages in the syngas of 5 closely followed by 10 % and an M ratio of 1.90. The change in cost between both ends is 24.10 %, while the difference in emission ascends to 28.29 %.