Method for improving total energy demand in a post-combustion carbon capture process with ionic absorbent

A method for improving the total energy demand required to separate carbon dioxide (CO2) from an aqueous ionic absorbent solution in a post-combustion carbon capture process, the method comprising (a) contacting a flue gas stream containing CO2 with an aqueous ionic absorbent solution under absorption conditions to absorb at least a portion of the CO2 from the flue gas stream and a CO2-aqueous ionic absorbent solution stream, wherein the aqueous ionic absorbent solution comprises about 25 wt. % to about 60 wt. % of one or more diluents, based on the total weight of the aqueous ionic absorbent solution, of one or more diluents and an ionic absorbent containing a cation and an anion comprising an amine moiety, wherein the cation comprises one or more cations selected from the group consisting of an ammonium cation, a phosphonium cation, a Group 1 metal cation and a Group 2 metal cation and the anion comprising an amine moiety is represented by the general formula:

• R1—N(R1)-(L)-A−
• wherein R1 is the same or different and includes hydrogen, a straight or branched C1 to C30 substituted or unsubstituted alkyl group, a C1 to C20 ester-containing group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C3 to C30 cycloalkylalkyl group, a substituted or unsubstituted C3 to C30 cycloalkenyl group, a substituted or unsubstituted C5 to C30 aryl group, a substituted or unsubstituted C5 to C30 arylalkyl group, a substituted or unsubstituted C5 to C30 heteroaryl group, a substituted or unsubstituted C3 to C30 heterocyclic ring, a substituted or unsubstituted C4 to C30 heterocyclolalkyl group, a substituted or unsubstituted C6 to C30 heteroarylalkyl group, or R1 and R1 together with the nitrogen atom to which they are bonded are joined together to form a heterocyclic group;
• L is a linking group;
• and A− is an anionic moiety;
• and (b) subjecting at least a portion of the CO2-aqueous ionic absorbent solution stream to desorption conditions to form a CO2-rich stream and an aqueous ionic absorbent solution stream having a reduced CO2 content, wherein the method reduces the total energy demand required to separate CO2 from an aqueous ionic absorbent solution in a post combustion carbon capture process.