Research on CO2 capture performance of DMEDA water-lean absorbents based on molecular dynamics

Abstract

In recent years, a large number of studies have shown that amine based water-lean absorbents formed by amines and organic solvents exhibit high capture efficiency and low regeneration energy consumption in CO2 capture. However, there is a lack of research that combines molecular level structure with macroscopic properties. In order to optimize the performance of amine based homogeneous water-lean absorbents by utilizing the properties of organic solvents, and to explore the correlation between the macroscopic properties of the absorbents (CO2 capacity, removal efficiency, regeneration rate, regeneration efficiency, etc.) and the molecular structure of the absorbent components. We used experiments and molecular dynamics to study the linear terminal diamine DMEDA and non-proton polar solvent (DMF, DMPA, NMP, SFL, DMSO) system. It was found that the absorption and desorption performance of water-lean solvents was higher than that of aqueous solutions 30 wt% MEA and 30 wt% DMEDA, among which EFH with DMF as the solvent has better comprehensive performance. The molecular dynamics simulation was built to describe the solution structures of these absorbents. Through RDF calculations, the unique behavior of DMEDA in non-proton polar solvent was revealed on molecular level, it was found that organic solvents tend to aggregate with DMEDA molecules to form large molecular clusters, while CO2 molecules may diffuse through ordered pore structures, resulting in a significant improvement in the capture performance. And it was found that there is a quantitative relationship between the intensity of intermolecular interaction between DMEDA and CO2 and the removal efficiency change in DMEDA water-lean absorbents. A functional relationship was fitted, and a preliminary and rapid method for determining capture performance through molecular dynamics was proposed.