(174cc) Monoethanolamine Based DES for CO2 Absorption: Insights from Molecular Dynamics Simulations

Several ionic liquids have been designed to absorb CO₂ and thereby decrease greenhouse gas emissions. Among them, novel deep eutectic solvents (DESs), with their commercially attractive properties, have recently been studied for CO₂ capture process. In our previous work we have studied molecular structure of DESs composed methyltriphenylphosphonium bromide (MTPPBr) and mono ethanol amine (MEA) at molar ratio 1:6, 1:7 and 1:8, which are known to have high CO₂ absorption capacity.

In current work, we analyze interactions between above mentioned DESs and CO₂ using molecular dynamics simulations to understand CO₂ absorption process. Results based on interaction energy and radial distribution functions (rdfs) have shown strong interactions between MEA/Br and CO₂ suggesting the capture of CO₂ by these compounds. Additionally, low diffusion coefficients of ions suggest high viscosity of DESs, an impediment to its commercial development. Water was added to DESs in different amount, to analyze the influence of water on to DESs’ viscosity. Results show that structure of DESs remains same up to 50% of water in DESs, while viscosity of DESs starts to decrease significantly above 50%. For same purpose, DESs were also examined at higher temperature that lead to significant decrease of viscosity. Taken together, work assists in understanding interactions between CO₂ and DESs’ component and CO₂ absorption mechanism, additionally it suggests methods to decrease DESs viscosity, along with optimized process conditions, for further industrial implementation.