Molecular engineering of sustainable phase-change solvents: From digital design to scaling-up for CO<inf>2</inf> capture

A. I. Papadopoulos; Felipe A. Perdomo; Fragkiskos Tzirakis; Gulnara Shavalieva; Ioannis Tsivintzelis; Panagiotis Kazepidis; Evie Nessi; Stavros Papadokonstantakis; P. Seferlis; Amparo Galindo; George Jackson; Claire S. Adjiman

doi:10.1016/j.cej.2020.127624

Molecular engineering of sustainable phase-change solvents: From digital design to scaling-up for CO2 capture
Journal article, 2021

Phase-change solvents promise reduced energetic and environmental footprints for separation systems, including absorption-based CO2 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 S1N (N1-cyclohexylpropane-1,3-diamine) and mixture S1N/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 S1N/DMCA for scaling-up, with a cyclic capacity of 1.19 mol CO2/ kg-solvent, a regeneration energy of 2.3 GJ/ton-CO2, and vapour losses and viscosity lower by 10% and 70% than those of other solvents. S1N is also safer for plant operation and working personnel.

Phase-change solvents

Vapour-liquid-liquid equilibrium

Regeneration energy

Viscosity

SAFT

Chemisorption

CO capture 2

Sustainability assessment

Molecular design