Molecular engineering of sustainable phase-change solvents: From digital design to scaling-up for CO2 capture

Abstract

• Digital design and experimental validation of phase-change CO 2 capture solvents. • Evaluation of thermodynamics, reactivity, process and sustainability properties. • SAFT-γ Mie predicts entire three-phase envelope for S 1 N/DMCA + H 2 O + CO 2 . • Low regeneration energy, viscosity and vapour losses, high cyclic capacity. • Favourable health and safety performance compared to other solvents. Phase-change solvents promise reduced energetic and environmental footprints for separation systems, including absorption-based CO 2 abatement technologies. The search for efficient phase-change solvents is limited by challenges in vapour-liquid–liquid equilibrium (VLLE) prediction and in sustainability assessment. We overcome these with a digital approach to screen billions of structures and design the novel phase-change solvent S 1 N (N1-cyclohexylpropane-1,3-diamine) and mixture S 1 N/DMCA (N,N-dimethylcyclohexylamine). Screening criteria include thermodynamic and process-related properties, reactivity and sustainability of solvent production and use. VLLE phase envelopes are predicted using the SAFT-γ Mie (Statistical Associating Fluid Theory) equation of state thanks to its transferability to any structure and the implicit modelling of ionic species. Experimental validation confirms the suitability of S 1 N/DMCA for scaling-up, with a cyclic capacity of 1.19 mol CO 2 / kg-solvent, a regeneration energy of 2.3 GJ/ton-CO 2 , and vapour losses and viscosity lower by 10% and 70% than those of other solvents. S 1 N is also safer for plant operation and working personnel.