Integrated Process and Molecular Design for Ionic Liquid Solvent-Based Process Intensification

Abstract

Identifying suitable materials is crucial for developing sustainable, cost-effective, and energy-efficient chemical processes as they directly influence the operating conditions and process performance. However, selecting the optimal material while considering its desired properties incorporating process knowledge can be challenging due to the vastness of the chemical space. Research in Computer-aided Molecular and Process Design (CAMPD) has emerged to address these challenges that considers a systematic selection of processes and functional materials. However, integrating molecular and process scale decision-making within an optimization framework results in complex, non-convex mixed-integer nonlinear programs (MINLP), which can be difficult to solve.

To address the challenges in CAMPD, in this Ph.D. work, we have developed a decomposition-based approach for process and material design. This approach first maps feasible material property domains from rigorous process models and then using the feasibility map, designs optimal materials. The main objectives of this Ph.D. work are (i) developing a computational framework for optimal process synthesis and intensification, (ii) creating a methodology for mapping the relationship between material properties and process performance, and (iii) developing a new molecular design model by incorporating a universal molecular descriptor. The key contributions of this work include the development of SPICE, a computational process synthesis model that can perform benchmarking, targeting, conceptual design, process synthesis, optimization, simulation, and material-property-to-process-performance mapping. Additionally, the thesis proposes a novel decomposition-based integrated process and molecular design framework where optimal molecules are designed by incorporating the process knowledge. We applied the developed framework to separate hydrofluorocarbon (HFC), R-410A, using ionic liquids (ILs) in extractive distillation (ED) column. Our framework found [emim][dca] as the best existing IL, improving energy consumption and process sustainability by 28% and 26%, respectively, over the previously reported [bmim][PF6]-based process. The framework also suggests that the energy consumption can be further reduced by at least 13% compared to [emim][dca] if new ILs with moderate selectivity are discovered.