Energy-Efficient Styrene Production by Incorporating Ionic Liquid-Based Separation Technology

Abstract

The separation of ethylbenzene/styrene represents a pivotal step in the styrene production process, which is associated with significant energy consumption, substantial costs, and considerable environmental impact. In this study, ionic liquids (ILs) were incorporated into the separation process, thereby enabling energy-efficient styrene production through the use of extractive distillation. By solving a formulated mixed-integer nonlinear programming (MINLP) problem based on computer-aided ionic liquid design (CAILD), 1-methylpyridinium trifluoromethanesulfonate ([mPy][CF₃SO₃]) and 1-ethylpyridinium tetrafluoroborate ([C₂Py][BF₄]) were identified as optimal IL candidates for this application. Comprehensive process simulations and optimizations were conducted, focusing on energy consumption, environmental impact, and economic performance. In comparison to the conventional process, the [mPy][CF₃SO₃]-based and [C₂Py][BF₄]-based processes achieved reductions in energy consumption by 44.2 % and 59.0 %, respectively. Furthermore, there was a notable reduction in carbon emissions, amounting to 28.9 % and 25.4 %. However, processes utilizing [mPy][CF₃SO₃] showed an increase in total annual cost (TAC) by 11.8 %. Meanwhile, processes based on [C₂Py][BF₄] demonstrated a diminution in TAC by 3.7 %. Nonetheless, Monte Carlo simulations indicate that IL-based processes exhibit slightly better resilience to economic uncertainties compared to conventional processes. Overall, the significant energy and environmental benefits of IL-based processes highlight their potential in styrene production, especially with the implementation of active policies related to energy use and carbon emissions (e.g., carbon taxes).