Investigation of Rational Design of Amine Solvents for CO2 Capture: A Computational Approach

Abstract

Solvent selection and design are critical in the CO2 capture process as the choice of solvent directly impacts the cost of the process, capture efficiency, equipment size, and regeneration energy. In the present study, 1MPZ-PZ, PZ, PIP, DEEA and MEA-DEEA are analyzed in terms of interaction intensity (attractive and repulsive) and diffusivity by molecular dynamic simulation. A high intermolecular interaction intensity promotes CO2 absorption, while intra-molecular interaction intensity affects CO2 desorption during the regeneration process. Diffusivity is also an important factor for a fast CO2 uptake rate, which is desirable for efficient CO2 capture. The interpretation of diffusivity and intermolecular interaction intensity findings is conducted through mean square displacement and radial distribution function analysis, respectively. The order of interaction intensity in various amines is DEEA>MEA-DEEA>PIP>1MPZ-PZ. It shows that DEEA can increase the CO2 absorption rate as it shows the highest interaction intensity in pure and blended amine systems. The results of the intramolecular interaction intensity show that it is easier to regenerate DEEA, PIP, PZ, and 1MPZ than MEA. The temperature effect on the interaction intensity is revealed at higher temperatures, where the molecular structure becomes unstable due to higher thermal motion, which is the cause of lower interaction intensity. On the other hand, the mean square displacement analysis for the diffusivity rate shows that PZ shows the highest diffusivity rate compared to other selected solvents. The order of diffusivity rate in various pure and blended amine systems is PZ>PIP>1-MPZ-PZ>MEA-DEEA. The diffusivity of various amine solvent systems increases with temperature. As examined in this current research, assessing solvent characteristics holds significant importance in optimizing the most effective solvent system.