Postcombustion CO2 Capture Solvent Characterization Employing the Explicit Solvation Shell Model and Continuum...

Area of Science:

• Computational Chemistry
• Physical Chemistry

Background:

• Accurate prediction of pKa values is crucial for designing effective solvents.
• Existing solvation models require validation for specific applications like postcombustion CO2 capture (PCC).

Purpose of the Study:

• To extend the explicit solvation shell (ESS) model for calculating solvation free energies and pKa values of amines and alkanolamines.
• To compare the accuracy of ESS and continuum solvation models (PCM, SM8T, DivCon) for these calculations.
• To evaluate theoretical methods for gas-phase basicity and proton affinity relevant to PCC solvent selection.

Main Methods:

• Calculated solvation free energies and pKa's using the ESS model and continuum solvation models.
• Employed density functional theory (DFT) and composite methods (G3MP2B3, G3MP2, CBS-QB3, G4MP2) for gas-phase thermochemistry.
• Compared theoretical results with experimental data for amines and alkanolamines.

Main Results:

• The ESS model, combined with composite methods for gas-phase thermochemistry, demonstrated reasonable accuracy in pKa calculations for amines and alkanolamines.
• Error estimates for each theoretical model were determined by comparison with experimental results.
• The study identified a reliable method for validating pKa values of new potential PCC solvents.

Conclusions:

• The ESS model provides a validated approach for predicting the pKa of amines and alkanolamines.
• This method is valuable for assessing the suitability of new compounds as solvents in postcombustion CO2 capture processes.
• Accurate pKa prediction is essential for the development of efficient CO2 capture technologies.