Comparative Technoeconomic Analysis of Pathways for Electrochemical Reduction of CO<sub>2</sub> with Methanol to Produce Methyl Formate
Joshua M. Spurgeon, Nolan Theaker, Christine A. Phipps, Sandesh S. Uttarwar, Craig A. Grapperhaus
Abstract
Electrochemical CO2 reduction has promise as a technology that could help society reach carbon neutrality while producing valuable fuels and chemicals. Herein, the electrochemical synthesis of methyl formate, a product not observed in aqueous CO2 electrolysis, has been analyzed by a rigorous technoeconomic model to evaluate its commercial viability. Methyl formate synthesis has been demonstrated with high faradaic efficiency through the electroreduction of CO2 in methanol. Four competing approaches were analyzed: (1) electroreduction of captured CO2 in a dual CH3OH/H2O electrolyzer, (2) direct electroreduction of flue gas CO2 in a dual CH3OH/H2O electrolyzer, (3) electroreduction of captured CO2 in a CH3OH/CH3OH electrolyzer, and (4) electroreduction of captured CO2 in a H2O/H2O electrolyzer with a downstream CH3OH reactor. Sensitivity analyses, cost contour plots, and comparison plots were generated. The dual methanol/water electrolysis approach was the most cost competitive, with a levelized cost of methyl formate below the present market price. The all-methanol electrolysis route was more expensive due to increased methanol consumption and greater distillation costs. Methyl formate production through aqueous CO2 electrolysis to formic acid with a secondary esterification reaction was by far the most expensive approach, primarily due to the energy-intensive nature of distilling formic acid from water.