CO₂ Capture with Silylated Ethanolamines and Piperazines.

Area of Science:

• Chemical Engineering
• Materials Science
• Computational Chemistry

Background:

• Amine-based solutions are widely used for carbon dioxide (CO2) capture from industrial emissions and ambient air.
• Aminosilanes offer a potentially more reactive alternative due to the Si-N bond's enhanced affinity for CO2.

Purpose of the Study:

• To synthesize and investigate the CO2 reactivity of trimethylsilylated ethanolamines, diethanolamines, and piperazines.
• To compare the CO2 capture efficiency of these aminosilanes with traditional amine treatments.
• To elucidate the reaction mechanisms and thermodynamic properties using experimental and computational methods.

Main Methods:

• Synthesis of trimethylsilylated ethanolamines, diethanolamines, and piperazines.
• Characterization using NMR (1H, 13C, 29Si), RAMAN spectroscopy, and mass spectrometry.
• Single-crystal X-ray diffraction for product structural analysis.
• Density Functional Theory (DFT) calculations for geometry optimization, NBO analysis, and thermochemical data (gas and solvent phases).

Main Results:

• Successful synthesis and characterization of various trimethylsilylated amines.
• Experimental reaction enthalpies for CO2 capture were determined to be around -100 kJ/mol.
• DFT calculations predicted reaction enthalpies ranging from -37 to -107 kJ/mol, aligning with experimental findings.
• Structural analysis of the CO2-bis-trimethylsilylated piperazine adduct provided detailed insights into the reaction product.

Conclusions:

• Trimethylsilylated amines, particularly piperazine derivatives, demonstrate significant potential for efficient CO2 capture.
• The Si-N bond plays a crucial role in enhancing the reactivity towards CO2.
• Combined experimental and computational approaches provide a comprehensive understanding of the CO2 capture mechanism and thermodynamics.