Eco-Friendly Ionic Liquid Halves Energy Use in Industrial Chemical Separation

Dimethyl carbonate (DMC) is a versatile "green" chemical used in producing plastics, pharmaceuticals, and pesticides, and can even serve as a gasoline additive. Yet its industrial production always creates methanol as a by-product—the two chemicals form an azeotrope, a mixture that cannot be separated by conventional distillation. This bottleneck has long forced the chemical industry to use energy-intensive methods like pressure-swing distillation.

Now, a Chinese research team has proposed a solution that cuts energy use by nearly half. Their multi-scale strategy, published recently, pairs a tailor-made ionic liquid with heat pump-assisted distillation for sustainable, cost-effective separation of the DMC-methanol mixture.

“The DMC-methanol azeotrope is a classic headache in chemical processing,” says fist author Dr. Xin Guo from Liaoning Petrochemical University. “Traditional methods are energy-intensive. We asked: could a green solvent selectively ‘grab’ methanol, allowing smart engineering to recover that energy?”

The team first used COSMO-RS computer modeling to screen 169 ionic liquids—"designer solvents" that are liquid at room temperature. “We identified [MPY][DMP], a pyridine-based ionic liquid, as the top candidate for its exceptional ability to selectively interact with methanol over DMC,” shares Guo. “Laboratory vapor-liquid equilibrium experiments confirmed that adding just 3 mol/kg of this ionic liquid completely eliminated the azeotrope.”

“We then used molecular dynamics simulations to understand the mechanism,” adds co-corresponding author Dr. Jiahui Zhang from China University of Petroleum. “We found [MPY][DMP] forms strong hydrogen bonds specifically with methanol, effectively trapping those molecules and making separation straightforward.”

The team went further, using Aspen Plus software to design a vapor recompression heat pump-assisted extractive distillation process (HP-EDP). They found that 48.68% lower total energy consumption and 8.27% lower annual costs compared to conventional extractive distillation. “The ionic liquid itself costs roughly US$3.65 per kilogram—40–70% cheaper than most common ionic liquids, enhancing its real-world applicability,” says Zhang.

“This work provides ablueprint from molecular design to process optimization for greener azeotrope separation,” says co-corresponding author Dr. Yufeng Hu. “We believe this approach can serve as a model for tackling similar separation challenges throughout the chemical industry.”

Contact Author

Name: Dr. Xin Guo

Affiliation: Liaoning Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning Petrochemical University, Fushun 113001, PR China

Email: guoxin19940620@163.com

Funder

This work was supported by the Doctoral Initiation Project of Liaoning Provincial Department of Science and Technology, China (No. 2025BS4012), the talent scientific research fund of Liaoning Petrochemical University (2024XJJL-035), and the National Natural Science Foundation of China (No. 22478418 and 22078355).

Conflict of Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

See the Article

Guo, X., Jiao, C., Jiang, S., Zhang, J., Xu, Y., Su, Z., Liu, Q., Li, J., Hu, Y., "From molecular screening to process intensification: A green strategy for sustainable dimethyl carbonate/methanol separation via ionic liquid-heat pump hybrid design."

DOI: https://doi.org/10.1016/j.gce.2026.05.001