Theoretical study on the efficacy of DBN/LiBr system as a catalyst for fixation of CO2 with propylene oxide: Solvent effects on activation barriers

•The mechanism for DBN/LiBr mediated CO2/PO coupling reaction elucidated.•DBN/LiBr system shows high catalytic performance in solvents for fixation of CO2.•The favorable mechanism for the catalyzed pathway follows three steps: ring-opening, CO2 insertion, and ring-closure.•The catalytic activity of DBN/LiBr is compared with other related catalysts.