Multiscale evaluation of CO2-derived cyclic carbonates to separate hydrocarbons: Drafting new competitive processes

Abstract

Current chemical technologies present a negative impact on society and environment since they are based on processes that demand large energy and the use organic solvents, entailing relevant carbon footprint. Emerging solvents impose additional criteria in the design of new separation technologies. Aiming at addressing favorable solvent properties but also reducing emissions of carbon dioxide, cyclic carbonates are CO2-based synthesizable designer solvents unexplored in the literature. Cyclic carbonates are a new class of tunable compounds with ability to enhance current standards and improve the sustainability of processes. Here a comprehensive and systematic study, covering fundamental and process scale insights, is developed on the use of cyclic carbonates in the most relevant hydrocarbon separations in the literature, namely {n-heptane + toluene}, {cyclohexane + benzene} and {cyclohexane + cyclohexene} by liquid-liquid extraction and extractive distillation. A priori COSMO-RS method described the driving interactions between cyclic carbonates and hydrocarbons, whereas COSMO-based/Aspen was used to further inspect phase equilibria and design liquid-liquid extraction and extractive distillation separation processes, using benchmark industrial solvents (sulfolane and N-formylmorpholine). The favorable process performance starts a new research line to fine-tune cyclic carbonates' structure, but currently drafting feasible approaches, competitive or even better when compared with conventional solvents.