Application-specific thermodynamic favorability zones for direct air capture of carbon dioxide

Abstract

An increased interest in the capture and conversion of carbon dioxide into valuable chemical products is fueled by impending societal and ecological consequences of increasing CO₂ concentration in the atmosphere. This work utilizes Lackner's thermodynamic calculations for the capture of carbon dioxide from the atmosphere based on a single sorbent approximation to map thermodynamic favorability zones compatible with various applications. When a minimal amount of CO₂ is removed from the air stream, −4.64 kcal mol⁻¹ is estimated as the maximum free energy of binding for sorption to occur in atmospheric conditions at 1 atm pressure and room temperature. When complete scrubbing of CO₂ from a dilute source is desired, a more negative free energy of sorption is needed, with an estimated −10.92 kcal mol⁻¹ required for close to complete CO₂ removal from the stream.