A computational investigation on the structural features of alkanolamine solvents for CO2 capture process from power plant flue gas

The present study aimed at investigating the chemical properties of the solvents playing the key role in CO2 absorption process from the exhaust stream of power plants or other industrial sources. For this purpose, energy computations were performed using a DFT-based quantum chemistry method at B3LYP/6-311++G(d,p) level of theory. Furthermore, the solvent effect was taken into account by means of a dielectric constant in SMD continuum model at HF/6-31G(d) level of theory. With this approach, the relative stability of carbamate ion versus bicarbonate ion as the main products of CO2 absorption into the aqueous alkanolamine solvents was evaluated and the results were discussed in terms of various factors such as types of alkanolamine, carbon chain length in alkanolamine and steric hindrance. This study revealed that increasing both carbon chain length and steric hindrance leads to a decrease in carbamate stability. Moreover, DEA as a secondary alkanolamine demonstrated a lower carbamate stability.