Integrating CO₂ Capture 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 (CCU) technologies (i.e. capture and conversion) have been studied independently. In this communication, we report a novel methodology based on the integration of CO2 capture and conversion by the direct utilization of a CO2 capture media as 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 novel mixture of chemical and physical absorption solvents allowed for the captured CO2 to be converted to formic acid with faradaic efficiencies up to 50 % and with carbon conversion of ca. 30 %. By increasing the temperature in the electrochemical reactor from 20 °C to 75 °C, the productivity towards formic acid increased by a factor of 10, reaching up to 0.7 mmol•m-2 •s-1. The direct conversion of captured CO2 was also demonstrated for carbon monoxide formation with faradaic efficiencies up 45 %.

A State‐of‐the‐Art Update on Integrated CO2 Capture and Electrochemical Conversion Systems

“…They promoted the reaction rate by a factor of 10 by increasing the temperature up to 75 °C. [60] It is clear that, based on the studies published in recent years and discussed in this paper, reducing CO 2 that has been previously captured by an amine holds promise, but there is still room for improvement as compared to the typical gaseous CO 2 electrolyzers in terms of FE and current density. However, thanks to the advancement in understanding how to dissociate the CO 2 from the amine in the electrochemical reactor, the next studies can focus on optimizing engineering aspects of the reactor to achieve higher overall energy efficiency,…”

“…evaluated the performance of an amine‐based capture solvent as electrolyte for CO 2 conversion, achieving up to 50 % FE for formate and up to 45 % for CO with carbon conversion of 30 %. They promoted the reaction rate by a factor of 10 by increasing the temperature up to 75 °C [60] …”

Materials and system design for direct electrochemical CO2 conversion in capture media

“…Using amines with high concentration or high viscosity as electrolytes for direct electrolysis may lead to a decrease in reaction rate and efficiency due to mass transfer limitations. 41 Trace impurities, such as SOx and NOx, are common in point source emissions. 42 The influence of these impurities should be considered carefully.…”

Insensitive cation effect on single-atom Ni catalyst allows selective electrochemical conversion of captured CO2 in universal media

“…1a). [16][17][18][19][20][21][22][23][24][25][26][27] However, inferior selectivity toward CO or formate has been exhibited compared with that of the conventional CO 2 -fed electrochemical reduction reaction (CO 2 RR). 28 The electrocatalytic activity is determined by the charge transfer at the electrode-electrolyte interface, which necessitates the thorough investigation of cCO 2 RR in terms of the interactions with the absorbent medium to improve the conversion activity.…”