Analysis of carbon dioxide-to-methanol direct electrochemical conversion mediated by an ionic liquid

An intensified process for carbon dioxide capture and conversion is proposed and analyzed, considering an electrochemical parallel plate reactor which processes a CO₂-charged stream from an absorption unit at 40°C and atmospheric pressure and where the target product of the conversion is methanol. The task-specific ionic liquid 1-(3-aminopropyl)-3-methylimidazolium bromide was selected, synthesized and characterized. This ionic liquid has shown a good absorption capacity, high ionic conductivity, high chemical-electrochemical stability and acts as a charged intermediate (CO₂^*-) stabilizer, enabling the electrochemical reduction of absorbed CO₂.The electrical energy in the electrochemical reactor was estimated to be 8.683kWhkg (CO₂)^-1 or 115.16g (CO₂) kWh^-1, too high to ensure the environmental sustainability of the process. A low concentration of carbon dioxide in the liquid phase, at ambient conditions, implies the need for a high electrode area for the process and is a major hindrance to improving the economy of the process.