Toward Sustainable and Cost-Effective CO2 Conversion Processes to Propylene Carbonate Based on Ionic Liquids

The use of ionic liquids (ILs) for CO2 capture and utilization into a valuable product is attracting interest even though literature evaluating their sustainability is scarce. A liquid-liquid extraction (LLE)-based separation is recently proposed as an alternative to the high energy-consuming distillation-based reference approach to produce propylene carbonate (PC). In this work, the environmental impacts associated to the distillation-based reference and two proposed LLE-based approaches to produce PC are evaluated by means of process modeling and life cycle impact assessment tools. Simulations prove that tuning operating variables in terms of environmental benefits also improves the cost-effectiveness of the process. In addition, sustainability of the processes is nearly not altered by the IL selection when an effective recovery is designed. The emissions associated to the proposed approaches vary between 0.12 and 0.22 kg CO2 equiv. per kg(PC), while the operational costs range from 3 to 8 $ per t(PC). The water-mediated LLE-based approach imposes the best environmental, capital expenditures, and operating expenses performance.