Intensified direct synthesis of dimethyl carbonate from CO2 using 1-alkyl-3-methylimidazolium triazolide ionic liquids by reactive extraction strategy

The direct synthesis of dimethyl carbonate (DMC) from CO 2 is a promising route for CO 2 utilization, however it is constrained by high CO 2 activation barrier and inherent thermodynamic limitations. Herein, we developed a reactive extraction strategy to intensify the reaction through 1-alkyl-3-methylimidazolium triazolide ionic liquids (ILs) (CnMImTz, n = 2, 4, 6, and 8) by modulating IL polarity. The absorption and activation mechanism of CO 2 in ILs was demonstrated, and subsequent transformation into DMC can be achieved under mild conditions. Remarkably, C2MImTz achieves the highest DMC yield (9.4 % after 12 h at 25 °C), revealing chain-length dependent catalytic efficiency of IL analogs at both kinetics- and thermodynamic-controlled stages. Phase analyses, binding energy calculations, and molecular dynamics simulations revealed that the highly polar C2MImTz preferentially concentrate CH 3 OH and H 2 O, while spontaneously segregating weakly polar DMC into a separate phase. The enhanced CH 3 OH concentration and diffusion coefficients promote the mass transfer and reaction kinetics. Moreover, the segregation of DMC can effectively shift thermodynamic equilibrium toward DMC formation. Therefore, the integrated absorption-conversion-separation process within a single functionalized IL presents a scalable platform for CO 2 capture and utilization.