Concentration-Dependent Nanoscale Network Connectivity in Water-Lean CO₂ Capture Solvent Clusters Revealed by...

Area of Science:

• Chemical Engineering
• Materials Science
• Physical Chemistry

Background:

• Water-lean solvents are crucial for point source carbon dioxide (CO2) capture.
• N-(2-ethoxyethyl)-3-morpholinopropan-1-amine (2-EEMPA) shows promise due to CO2-dependent tetramer formation.
• Understanding structural changes at varying CO2 loadings is key to solvent design.

Purpose of the Study:

• To investigate the nanoscale structural evolution of 2-EEMPA with increasing CO2 loading.
• To correlate structural changes with solvent properties and CO2 capture efficiency.
• To provide quantitative structural data for modeling and designing improved CO2 capture solvents.

Main Methods:

• Wide-angle X-ray scattering (WAXS) to analyze nanoscale clusters from 0 to 42 mol % CO2 and -17 to 90 °C.
• Computational modeling and experimental data for solvent density and cluster correlations.
• Teubner-Strey model for microphase separation analysis.
• Scattering and molecular dynamics for structure factor analysis.

Main Results:

• Nanoscale cluster size (ξ) and periodicity (d) of CO2-bound 2-EEMPA grow with CO2 concentration.
• Experimentally determined values reached ξ = 5.0 Å and d = 11.6 Å.
• Results align with computational simulation data.
• Detailed structural changes were observed across varying CO2 conditions.

Conclusions:

• CO2 loading significantly impacts the nanoscale structure of 2-EEMPA.
• The observed growth in cluster size and periodicity is directly linked to CO2 capture.
• These structural insights are vital for optimizing the performance of CO2 capture solvents.