Integrating CO₂Capture with Electrochemical Conversion Using Amine-Based Capture Solvents as Electrolytes

Abstract

Carbon dioxide (CO2) is currently considered as a waste material due to its negative impact on the environment. However, it is possible to create value from CO2 by capturing and utilizing it as a building block for commodity chemicals. Electrochemical conversion of CO2 has excellent potential for reducing greenhouse gas emissions and reaching the Paris agreement goal of zero net emissions by 2050. To date, carbon capture and utilization technologies (i.e., capture and conversion) have been studied mostly independently. In this communication, we report a methodology based on the integration of CO2 capture and conversion by the direct utilization of a CO2 capture media as the electrolyte for electrochemical conversion of CO2. This has a high potential for reducing capital and operational cost when compared to traditional methodologies (i.e., capture, desorption, and then utilization). A mixture of chemical and physical absorption solvents allowed for the captured CO2 to be converted to formate with faradaic efficiencies of up to 50% and with carbon conversion of ca. 30%. By increasing the temperature in the electrochemical reactor from 20 to 75 °C, the reaction rate toward formate increased by a factor of 10, reaching up to 0.7 mmol/m2·s. The direct conversion of captured CO2 was also demonstrated for carbon monoxide formation with faradaic efficiencies of up to 45%.