Diamine solvent system for CO2 capture

A method, comprising:

• contacting a gas stream comprising a first amount of CO2 with a CO2-lean solvent stream comprising a compound according to Formula I, to form a treated gas stream comprising a second amount of CO2 that is less than the first amount, and to form a CO2-rich solvent stream;
• and
• heating the CO2-rich solvent stream to form a CO2 stream and regenerate the CO2-lean solvent;
• wherein the compound according to Formula I has a structure
• R1(R2)N-L1-NH—R3 Formula I
• each of R1 and R2 independently is aliphatic, cycloaliphatic, or R1 and R2 together with the nitrogen to which they are attached, form a heterocyclyl ring;
• L1 is aliphatic, cycloaliphatic, or L1 and R1 together with the nitrogen to which they are attached form a heterocyclyl ring;
• and
• R3 is aliphatic, cycloaliphatic, cycloalkylalkyl, or alkoxyalkyl;
• and
• wherein
• the CO2-lean solvent stream consists essentially of the compound of Formula I;
• and
• the compound according to Formula I is not